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--- old/usr/src/man/man3tecla/gl_get_line.3tecla
+++ new/usr/src/man/man3tecla/gl_get_line.3tecla
1 1 '\" te
2 2 .\" Copyright (c) 2000, 2001, 2002, 2003, 2004 by Martin C. Shepherd.
3 3 .\" All Rights Reserved.
4 4 .\" Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the
5 5 .\" "Software"), to deal in the Software without restriction, including
6 6 .\" without limitation the rights to use, copy, modify, merge, publish,
7 7 .\" distribute, and/or sell copies of the Software, and to permit persons
8 8 .\" to whom the Software is furnished to do so, provided that the above
9 9 .\" copyright notice(s) and this permission notice appear in all copies of
10 10 .\" the Software and that both the above copyright notice(s) and this
11 11 .\" permission notice appear in supporting documentation.
12 12 .\"
13 13 .\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
14 14 .\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
15 15 .\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
16 16 .\" OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
17 17 .\" HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
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18 18 .\" INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
19 19 .\" FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
20 20 .\" NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
21 21 .\" WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
22 22 .\"
23 23 .\" Except as contained in this notice, the name of a copyright holder
24 24 .\" shall not be used in advertising or otherwise to promote the sale, use
25 25 .\" or other dealings in this Software without prior written authorization
26 26 .\" of the copyright holder.
27 27 .\" Portions Copyright (c) 2007, Sun Microsystems, Inc. All Rights Reserved.
28 -.TH GL_GET_LINE 3TECLA "Nov 28, 2007"
28 +.TH GL_GET_LINE 3TECLA "Sep 10, 2013"
29 29 .SH NAME
30 30 gl_get_line, new_GetLine, del_GetLine, gl_customize_completion,
31 31 gl_change_terminal, gl_configure_getline, gl_load_history, gl_save_history,
32 32 gl_group_history, gl_show_history, gl_watch_fd, gl_inactivity_timeout,
33 33 gl_terminal_size, gl_set_term_size, gl_resize_history, gl_limit_history,
34 34 gl_clear_history, gl_toggle_history, gl_lookup_history, gl_state_of_history,
35 35 gl_range_of_history, gl_size_of_history, gl_echo_mode, gl_replace_prompt,
36 36 gl_prompt_style, gl_ignore_signal, gl_trap_signal, gl_last_signal,
37 37 gl_completion_action, gl_register_action, gl_display_text, gl_return_status,
38 38 gl_error_message, gl_catch_blocked, gl_list_signals, gl_bind_keyseq,
39 39 gl_erase_terminal, gl_automatic_history, gl_append_history, gl_query_char,
40 40 gl_read_char \- allow the user to compose an input line
41 41 .SH SYNOPSIS
42 42 .LP
43 43 .nf
44 44 cc [ \fIflag\fR\&.\|.\|. ] \fIfile\fR\&.\|.\|. \fB-ltecla\fR [ \fIlibrary\fR\&.\|.\|. ]
45 45 #include <stdio.h>
46 46 #include <libtecla.h>
47 47
48 48 \fBGetLine *\fR\fBnew_GetLine\fR(\fBsize_t\fR \fIlinelen\fR, \fBsize_t\fR \fIhistlen\fR);
49 49 .fi
50 50
51 51 .LP
52 52 .nf
53 53 \fBGetLine *\fR\fBdel_GetLine\fR(\fBGetLine *\fR\fIgl\fR);
54 54 .fi
55 55
56 56 .LP
57 57 .nf
58 58 \fBchar *\fR\fBgl_get_line\fR(\fBGetLine *\fR\fIgl\fR, \fBconst char *\fR\fIprompt\fR,
59 59 \fBconst char *\fR\fIstart_line\fR, \fBint\fR \fIstart_pos\fR);
60 60 .fi
61 61
62 62 .LP
63 63 .nf
64 64 \fBint\fR \fBgl_query_char\fR(\fBGetLine *\fR\fIgl\fR, \fBconst char *\fR\fIprompt\fR, \fBchar\fR \fIdefchar\fR);
65 65 .fi
66 66
67 67 .LP
68 68 .nf
69 69 \fBint\fR \fBgl_read_char\fR(\fBGetLine *\fR\fIgl\fR);
70 70 .fi
71 71
72 72 .LP
73 73 .nf
74 74 \fBint\fR \fBgl_customize_completion\fR(\fBGetLine *\fR\fIgl\fR, \fBvoid *\fR\fIdata\fR,
75 75 \fBCplMatchFn *\fR\fImatch_fn\fR);
76 76 .fi
77 77
78 78 .LP
79 79 .nf
80 80 \fBint\fR \fBgl_change_terminal\fR(\fBGetLine *\fR\fIgl\fR, \fBFILE *\fR\fIinput_fp\fR,
81 81 \fBFILE *\fR\fIoutput_fp\fR, \fBconst char *\fR\fIterm\fR);
82 82 .fi
83 83
84 84 .LP
85 85 .nf
86 86 \fBint\fR \fBgl_configure_getline\fR(\fBGetLine *\fR\fIgl\fR, \fBconst char *\fR\fIapp_string\fR,
87 87 \fBconst char *\fR\fIapp_file\fR,\ \fBconst char *\fR\fIuser_file\fR);
88 88 .fi
89 89
90 90 .LP
91 91 .nf
92 92 \fBint\fR \fBgl_bind_keyseq\fR(\fBGetLine *\fR\fIgl\fR, \fBGlKeyOrigin\fR \fIorigin\fR,
93 93 \fBconst char *\fR\fIkeyseq\fR, \fBconst char *\fR\fIaction\fR);
94 94 .fi
95 95
96 96 .LP
97 97 .nf
98 98 \fBint\fR \fBgl_save_history\fR(\fBGetLine *\fR\fIgl\fR, \fBconst char *\fR\fIfilename\fR,
99 99 \fBconst char *\fR\fIcomment\fR, \fBint\fR \fImax_lines\fR);
100 100 .fi
101 101
102 102 .LP
103 103 .nf
104 104 \fBint\fR \fBgl_load_history\fR(\fBGetLine *\fR\fIgl\fR, \fBconst char *\fR\fIfilename\fR,
105 105 \fBconst char *\fR\fIcomment\fR);
106 106 .fi
107 107
108 108 .LP
109 109 .nf
110 110 \fBint\fR \fBgl_watch_fd\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fIfd\fR, \fBGlFdEvent\fR \fIevent\fR,
111 111 \fBGlFdEventFn *\fR\fIcallback\fR, \fBvoid *\fR\fIdata\fR);
112 112 .fi
113 113
114 114 .LP
115 115 .nf
116 116 \fBint\fR \fBgl_inactivity_timeout\fR(\fBGetLine *\fR\fIgl\fR, \fBGlTimeoutFn *\fR\fIcallback\fR,
117 117 \fBvoid *\fR\fIdata\fR, \fBunsigned long\fR \fIsec\fR, \fBunsigned long\fR \fInsec\fR);
118 118 .fi
119 119
120 120 .LP
121 121 .nf
122 122 \fBint\fR \fBgl_group_history\fR(\fBGetLine *\fR\fIgl\fR, \fBunsigned\fR \fIstream\fR);
123 123 .fi
124 124
125 125 .LP
126 126 .nf
127 127 \fBint\fR \fBgl_show_history\fR(\fBGetLine *\fR\fIgl\fR, \fBFILE *\fR\fIfp\fR, \fBconst char *\fR\fIfmt\fR,
128 128 \fBint\fR \fIall_groups\fR, \fBint\fR \fImax_lines\fR);
129 129 .fi
130 130
131 131 .LP
132 132 .nf
133 133 \fBint\fR \fBgl_resize_history\fR(\fBGetLine *\fR\fIgl\fR, \fBsize_t\fR \fIbufsize\fR);
134 134 .fi
135 135
136 136 .LP
137 137 .nf
138 138 \fBvoid\fR \fBgl_limit_history\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fImax_lines\fR);
139 139 .fi
140 140
141 141 .LP
142 142 .nf
143 143 \fBvoid\fR \fBgl_clear_history\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fIall_groups\fR);
144 144 .fi
145 145
146 146 .LP
147 147 .nf
148 148 \fBvoid\fR \fBgl_toggle_history\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fIenable\fR);
149 149 .fi
150 150
151 151 .LP
152 152 .nf
153 153 \fBGlTerminalSize\fR \fBgl_terminal_size\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fIdef_ncolumn\fR,
154 154 \fBint\fR \fIdef_nline\fR);
155 155 .fi
156 156
157 157 .LP
158 158 .nf
159 159 \fBint\fR \fBgl_set_term_size\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fIncolumn\fR, \fBint\fR \fInline\fR);
160 160 .fi
161 161
162 162 .LP
163 163 .nf
164 164 \fBint\fR \fBgl_lookup_history\fR(\fBGetLine *\fR\fIgl\fR, \fBunsigned long\fR \fIid\fR,
165 165 \fBGlHistoryLine *\fR\fIhline\fR);
166 166 .fi
167 167
168 168 .LP
169 169 .nf
170 170 \fBvoid\fR \fBgl_state_of_history\fR(\fBGetLine *\fR\fIgl\fR, \fBGlHistoryState *\fR\fIstate\fR);
171 171 .fi
172 172
173 173 .LP
174 174 .nf
175 175 \fBvoid\fR \fBgl_range_of_history\fR(\fBGetLine *\fR\fIgl\fR, \fBGlHistoryRange *\fR\fIrange\fR);
176 176 .fi
177 177
178 178 .LP
179 179 .nf
180 180 \fBvoid\fR \fBgl_size_of_history\fR(\fBGetLine *\fR\fIgl\fR, \fBGlHistorySize *\fR\fIsize\fR);
181 181 .fi
182 182
183 183 .LP
184 184 .nf
185 185 \fBvoid\fR \fBgl_echo_mode\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fIenable\fR);
186 186 .fi
187 187
188 188 .LP
189 189 .nf
190 190 \fBvoid\fR \fBgl_replace_prompt\fR(\fBGetLine *\fR\fIgl\fR, \fBconst char *\fR\fIprompt\fR);
191 191 .fi
192 192
193 193 .LP
194 194 .nf
195 195 \fBvoid\fR \fBgl_prompt_style\fR(\fBGetLine *\fR\fIgl\fR, \fBGlPromptStyle\fR \fIstyle\fR);
196 196 .fi
197 197
198 198 .LP
199 199 .nf
200 200 \fBint\fR \fBgl_ignore_signal\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fIsigno\fR);
201 201 .fi
202 202
203 203 .LP
204 204 .nf
205 205 \fBint\fR \fBgl_trap_signal\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fIsigno\fR, \fBunsigned\fR \fIflags\fR,
206 206 \fBGlAfterSignal\fR \fIafter\fR, \fBint\fR \fIerrno_value\fR);
207 207 .fi
208 208
209 209 .LP
210 210 .nf
211 211 \fBint\fR \fBgl_last_signal\fR(\fBGetLine *\fR\fIgl\fR);
212 212 .fi
213 213
214 214 .LP
215 215 .nf
216 216 \fBint\fR \fBgl_completion_action\fR(\fBGetLine *\fR\fIgl\fR, \fBvoid *\fR\fIdata\fR,
217 217 \fBCplMatchFn *\fR\fImatch_fn\fR, \fBint\fR \fIlist_only\fR, \fBconst char *\fR\fIname\fR,
218 218 \fBconst char *\fR\fIkeyseq\fR);
219 219 .fi
220 220
221 221 .LP
222 222 .nf
223 223 \fBint\fR \fBgl_register_action\fR(\fBGetLine *\fR\fIgl\fR, \fBvoid *\fR\fIdata\fR, \fBGlActionFn *\fR\fIfn\fR,
224 224 \fBconst char *\fR\fIname\fR, \fBconst char *\fR\fIkeyseq\fR);
225 225 .fi
226 226
227 227 .LP
228 228 .nf
229 229 \fBint\fR \fBgl_display_text\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fIindentation\fR,
230 230 \fBconst char *\fR\fIprefix\fR, \fBconst char *\fR\fIsuffix\fR, \fBint\fR \fIfill_char\fR,
231 231 \fBint\fR \fIdef_width\fR, \fBint\fR \fIstart\fR, \fBconst char *\fR\fIstring\fR);
232 232 .fi
233 233
234 234 .LP
235 235 .nf
236 236 \fBGlReturnStatus\fR \fBgl_return_status\fR(\fBGetLine *\fR\fIgl\fR);
237 237 .fi
238 238
239 239 .LP
240 240 .nf
241 241 \fBconst char *\fR\fBgl_error_message\fR(\fBGetLine *\fR\fIgl\fR, \fBchar *\fR\fIbuff\fR, \fBsize_t\fR \fIn\fR);
242 242 .fi
243 243
244 244 .LP
245 245 .nf
246 246 \fBvoid\fR \fBgl_catch_blocked\fR(\fBGetLine *\fR\fIgl\fR);
247 247 .fi
248 248
249 249 .LP
250 250 .nf
251 251 \fBint\fR \fBgl_list_signals\fR(\fBGetLine *\fR\fIgl\fR, \fBsigset_t *\fR\fIset\fR);
252 252 .fi
253 253
254 254 .LP
255 255 .nf
256 256 \fBint\fR \fBgl_append_history\fR(\fBGetLine *\fR\fIgl\fR, \fBconst char *\fR\fIline\fR);
257 257 .fi
258 258
259 259 .LP
260 260 .nf
261 261 \fBint\fR \fBgl_automatic_history\fR(\fBGetLine *\fR\fIgl\fR, \fBint\fR \fIenable\fR);
262 262 .fi
263 263
264 264 .LP
265 265 .nf
266 266 \fBint\fR \fBgl_erase_terminal\fR(\fBGetLine *\fR\fIgl\fR);
267 267 .fi
268 268
269 269 .SH DESCRIPTION
270 270 .sp
271 271 .LP
272 272 The \fBgl_get_line()\fR function is part of the \fBlibtecla\fR(3LIB) library.
273 273 If the user is typing at a terminal, each call prompts them for an line of
274 274 input, then provides interactive editing facilities, similar to those of the
275 275 UNIX \fBtcsh\fR shell. In addition to simple command-line editing, it supports
276 276 recall of previously entered command lines, TAB completion of file names, and
277 277 in-line wild-card expansion of filenames. Documentation of both the user-level
278 278 command-line editing features and all user configuration options can be found
279 279 on the \fBtecla\fR(5) manual page.
280 280 .SS "An Example"
281 281 .sp
282 282 .LP
283 283 The following shows a complete example of how to use the \fBgl_get_line()\fR
284 284 function to get input from the user:
285 285 .sp
286 286 .in +2
287 287 .nf
288 288 #include <stdio.h>
289 289 #include <locale.h>
290 290 #include <libtecla.h>
291 291
292 292 int main(int argc, char *argv[])
293 293 {
294 294 char *line; /* The line that the user typed */
295 295 GetLine *gl; /* The gl_get_line() resource object */
296 296
297 297 setlocale(LC_CTYPE, ""); /* Adopt the user's choice */
298 298 /* of character set. */
299 299
300 300 gl = new_GetLine(1024, 2048);
301 301 if(!gl)
302 302 return 1;
303 303 while((line=gl_get_line(gl, "$ ", NULL, -1)) != NULL &&
304 304 strcmp(line, "exit\en") != 0)
305 305 printf("You typed: %s\en", line);
306 306
307 307 gl = del_GetLine(gl);
308 308 return 0;
309 309 }
310 310 .fi
311 311 .in -2
312 312
313 313 .sp
314 314 .LP
315 315 In the example, first the resources needed by the \fBgl_get_line()\fR function
316 316 are created by calling \fBnew_GetLine()\fR. This allocates the memory used in
317 317 subsequent calls to the \fBgl_get_line()\fR function, including the history
318 318 buffer for recording previously entered lines. Then one or more lines are read
319 319 from the user, until either an error occurs, or the user types exit. Then
320 320 finally the resources that were allocated by \fBnew_GetLine()\fR, are returned
321 321 to the system by calling \fBdel_GetLine()\fR. Note the use of the \fINULL\fR
322 322 return value of \fBdel_GetLine()\fR to make \fIgl\fR \fINULL\fR. This is a
323 323 safety precaution. If the program subsequently attempts to pass \fIgl\fR to
324 324 \fBgl_get_line()\fR, said function will complain, and return an error, instead
325 325 of attempting to use the deleted resource object.
326 326 .SS "The Functions Used In The Example"
327 327 .sp
328 328 .LP
329 329 The \fBnew_GetLine()\fR function creates the resources used by the
330 330 \fBgl_get_line()\fR function and returns an opaque pointer to the object that
331 331 contains them. The maximum length of an input line is specified by the
332 332 \fIlinelen\fR argument, and the number of bytes to allocate for storing history
333 333 lines is set by the \fIhistlen\fR argument. History lines are stored
334 334 back-to-back in a single buffer of this size. Note that this means that the
335 335 number of history lines that can be stored at any given time, depends on the
336 336 lengths of the individual lines. If you want to place an upper limit on the
337 337 number of lines that can be stored, see the description of the
338 338 \fBgl_limit_history()\fR function. If you do not want history at all, specify
339 339 \fIhistlen\fR as zero, and no history buffer will be allocated.
340 340 .sp
341 341 .LP
342 342 On error, a message is printed to \fBstderr\fR and \fINULL\fR is returned.
343 343 .sp
344 344 .LP
345 345 The \fBdel_GetLine()\fR function deletes the resources that were returned by a
346 346 previous call to \fBnew_GetLine()\fR. It always returns \fINULL\fR (for
347 347 example, a deleted object). It does nothing if the \fIgl\fR argument is
348 348 \fINULL\fR.
349 349 .sp
350 350 .LP
351 351 The \fBgl_get_line()\fR function can be called any number of times to read
352 352 input from the user. The gl argument must have been previously returned by a
353 353 call to \fBnew_GetLine()\fR. The \fIprompt\fR argument should be a normal
354 354 null-terminated string, specifying the prompt to present the user with. By
355 355 default prompts are displayed literally, but if enabled with the
356 356 \fBgl_prompt_style()\fR function, prompts can contain directives to do
357 357 underlining, switch to and from bold fonts, or turn highlighting on and off.
358 358 .sp
359 359 .LP
360 360 If you want to specify the initial contents of the line for the user to edit,
361 361 pass the desired string with the \fIstart_line\fR argument. You can then
362 362 specify which character of this line the cursor is initially positioned over by
363 363 using the \fIstart_pos\fR argument. This should be -1 if you want the cursor to
364 364 follow the last character of the start line. If you do not want to preload the
365 365 line in this manner, send \fIstart_line\fR as \fINULL\fR, and set
366 366 \fIstart_pos\fR to -1.
367 367 .sp
368 368 .LP
369 369 The \fBgl_get_line()\fR function returns a pointer to the line entered by the
370 370 user, or \fINULL\fR on error or at the end of the input. The returned pointer
371 371 is part of the specified \fIgl\fR resource object, and thus should not be freed
372 372 by the caller, or assumed to be unchanging from one call to the next. When
373 373 reading from a user at a terminal, there will always be a newline character at
374 374 the end of the returned line. When standard input is being taken from a pipe or
375 375 a file, there will similarly be a newline unless the input line was too long to
376 376 store in the internal buffer. In the latter case you should call
377 377 \fBgl_get_line()\fR again to read the rest of the line. Note that this behavior
378 378 makes \fBgl_get_line()\fR similar to \fBfgets\fR(3C). When \fBstdin\fR is not
379 379 connected to a terminal, \fBgl_get_line()\fR simply calls \fBfgets()\fR.
380 380 .SS "The Return Status Of \fBgl_get_line()\fR"
381 381 .sp
382 382 .LP
383 383 The \fBgl_get_line()\fR function has two possible return values: a pointer to
384 384 the completed input line, or \fINULL\fR. Additional information about what
385 385 caused \fBgl_get_line()\fR to return is available both by inspecting
386 386 \fBerrno\fR and by calling the \fBgl_return_status()\fR function.
387 387 .sp
388 388 .LP
389 389 The following are the possible enumerated values returned by
390 390 \fBgl_return_status()\fR:
391 391 .sp
392 392 .ne 2
393 393 .na
394 394 \fB\fBGLR_NEWLINE\fR\fR
395 395 .ad
396 396 .RS 15n
397 397 The last call to \fBgl_get_line()\fR successfully returned a completed input
398 398 line.
399 399 .RE
400 400
401 401 .sp
402 402 .ne 2
403 403 .na
404 404 \fB\fBGLR_BLOCKED\fR\fR
405 405 .ad
406 406 .RS 15n
407 407 The \fBgl_get_line()\fR function was in non-blocking server mode, and returned
408 408 early to avoid blocking the process while waiting for terminal I/O. The
409 409 \fBgl_pending_io()\fR function can be used to see what type of I/O
410 410 \fBgl_get_line()\fR was waiting for. See the \fBgl_io_mode\fR(3TECLA).
411 411 .RE
412 412
413 413 .sp
414 414 .ne 2
415 415 .na
416 416 \fB\fBGLR_SIGNAL\fR\fR
417 417 .ad
418 418 .RS 15n
419 419 A signal was caught by \fBgl_get_line()\fR that had an after-signal disposition
420 420 of \fBGLS_ABORT\fR. See \fBgl_trap_signal()\fR.
421 421 .RE
422 422
423 423 .sp
424 424 .ne 2
425 425 .na
426 426 \fB\fBGLR_TIMEOUT\fR\fR
427 427 .ad
428 428 .RS 15n
429 429 The inactivity timer expired while \fBgl_get_line()\fR was waiting for input,
430 430 and the timeout callback function returned \fBGLTO_ABORT\fR. See
431 431 \fBgl_inactivity_timeout()\fR for information about timeouts.
432 432 .RE
433 433
434 434 .sp
435 435 .ne 2
436 436 .na
437 437 \fB\fBGLR_FDABORT\fR\fR
438 438 .ad
439 439 .RS 15n
440 440 An application I/O callback returned \fBGLFD_ABORT\fR. Ssee
441 441 \fBgl_watch_fd()\fR.
442 442 .RE
443 443
444 444 .sp
445 445 .ne 2
446 446 .na
447 447 \fB\fBGLR_EOF\fR\fR
448 448 .ad
449 449 .RS 15n
450 450 End of file reached. This can happen when input is coming from a file or a
451 451 pipe, instead of the terminal. It also occurs if the user invokes the
452 452 list-or-eof or del-char-or-list-or-eof actions at the start of a new line.
453 453 .RE
454 454
455 455 .sp
456 456 .ne 2
457 457 .na
458 458 \fB\fBGLR_ERROR\fR\fR
459 459 .ad
460 460 .RS 15n
461 461 An unexpected error caused \fBgl_get_line()\fR to abort (consult \fBerrno\fR
462 462 and/or \fBgl_error_message()\fR for details.
463 463 .RE
464 464
465 465 .sp
466 466 .LP
467 467 When \fBgl_return_status()\fR returns \fBGLR_ERROR\fR and the value of
468 468 \fBerrno\fR is not sufficient to explain what happened, you can use the
469 469 \fBgl_error_message()\fR function to request a description of the last error
470 470 that occurred.
471 471 .sp
472 472 .LP
473 473 The return value of \fBgl_error_message()\fR is a pointer to the message that
474 474 occurred. If the \fIbuff\fR argument is \fINULL\fR, this will be a pointer to a
475 475 buffer within \fIgl\fR whose value will probably change on the next call to any
476 476 function associated with \fBgl_get_line()\fR. Otherwise, if a non-null
477 477 \fIbuff\fR argument is provided, the error message, including a '\e0'
478 478 terminator, will be written within the first \fIn\fR elements of this buffer,
479 479 and the return value will be a pointer to the first element of this buffer. If
480 480 the message will not fit in the provided buffer, it will be truncated to fit.
481 481 .SS "Optional Prompt Formatting"
482 482 .sp
483 483 .LP
484 484 Whereas by default the prompt string that you specify is displayed literally
485 485 without any special interpretation of the characters within it, the
486 486 \fBgl_prompt_style()\fR function can be used to enable optional formatting
487 487 directives within the prompt.
488 488 .sp
489 489 .LP
490 490 The \fIstyle\fR argument, which specifies the formatting style, can take any of
491 491 the following values:
492 492 .sp
493 493 .ne 2
494 494 .na
495 495 \fB\fBGL_FORMAT_PROMPT\fR\fR
496 496 .ad
497 497 .RS 21n
498 498 In this style, the formatting directives described below, when included in
499 499 prompt strings, are interpreted as follows:
500 500 .sp
501 501 .ne 2
502 502 .na
503 503 \fB\fB%B\fR\fR
504 504 .ad
505 505 .RS 6n
506 506 Display subsequent characters with a bold font.
507 507 .RE
508 508
509 509 .sp
510 510 .ne 2
511 511 .na
512 512 \fB\fB%b\fR\fR
513 513 .ad
514 514 .RS 6n
515 515 Stop displaying characters with the bold font.
516 516 .RE
517 517
518 518 .sp
519 519 .ne 2
520 520 .na
521 521 \fB\fB%F\fR\fR
522 522 .ad
523 523 .RS 6n
524 524 Make subsequent characters flash.
525 525 .RE
526 526
527 527 .sp
528 528 .ne 2
529 529 .na
530 530 \fB\fB%f\fR\fR
531 531 .ad
532 532 .RS 6n
533 533 Turn off flashing characters.
534 534 .RE
535 535
536 536 .sp
537 537 .ne 2
538 538 .na
539 539 \fB\fB%U\fR\fR
540 540 .ad
541 541 .RS 6n
542 542 Underline subsequent characters.
543 543 .RE
544 544
545 545 .sp
546 546 .ne 2
547 547 .na
548 548 \fB\fB%u\fR\fR
549 549 .ad
550 550 .RS 6n
551 551 Stop underlining characters.
552 552 .RE
553 553
554 554 .sp
555 555 .ne 2
556 556 .na
557 557 \fB\fB%P\fR\fR
558 558 .ad
559 559 .RS 6n
560 560 Switch to a pale (half brightness) font.
561 561 .RE
562 562
563 563 .sp
564 564 .ne 2
565 565 .na
566 566 \fB\fB%p\fR\fR
567 567 .ad
568 568 .RS 6n
569 569 Stop using the pale font.
570 570 .RE
571 571
572 572 .sp
573 573 .ne 2
574 574 .na
575 575 \fB\fB%S\fR\fR
576 576 .ad
577 577 .RS 6n
578 578 Highlight subsequent characters (also known as standout mode).
579 579 .RE
580 580
581 581 .sp
582 582 .ne 2
583 583 .na
584 584 \fB\fB%s\fR\fR
585 585 .ad
586 586 .RS 6n
587 587 Stop highlighting characters.
588 588 .RE
589 589
590 590 .sp
591 591 .ne 2
592 592 .na
593 593 \fB\fB%V\fR\fR
594 594 .ad
595 595 .RS 6n
596 596 Turn on reverse video.
597 597 .RE
598 598
599 599 .sp
600 600 .ne 2
601 601 .na
602 602 \fB\fB%v\fR\fR
603 603 .ad
604 604 .RS 6n
605 605 Turn off reverse video.
606 606 .RE
607 607
608 608 .sp
609 609 .ne 2
610 610 .na
611 611 \fB\fB%%\fR\fR
612 612 .ad
613 613 .RS 6n
614 614 Display a single % character.
615 615 .RE
616 616
617 617 For example, in this mode, a prompt string like "%UOK%u$" would display the
618 618 prompt "OK$", but with the OK part underlined.
619 619 .sp
620 620 Note that although a pair of characters that starts with a % character, but
621 621 does not match any of the above directives is displayed literally, if a new
622 622 directive is subsequently introduced which does match, the displayed prompt
623 623 will change, so it is better to always use %% to display a literal %.
624 624 .sp
625 625 Also note that not all terminals support all of these text attributes, and that
626 626 some substitute a different attribute for missing ones.
627 627 .RE
628 628
629 629 .sp
630 630 .ne 2
631 631 .na
632 632 \fB\fBGL_LITERAL_PROMPT\fR\fR
633 633 .ad
634 634 .RS 21n
635 635 In this style, the prompt string is printed literally. This is the default
636 636 style.
637 637 .RE
638 638
639 639 .SS "Alternate Configuration Sources"
640 640 .sp
641 641 .LP
642 642 By default users have the option of configuring the behavior of
643 643 \fBgl_get_line()\fR with a configuration file called \fB\&.teclarc\fR in their
644 644 home directories. The fact that all applications share this same configuration
645 645 file is both an advantage and a disadvantage. In most cases it is an advantage,
646 646 since it encourages uniformity, and frees the user from having to configure
647 647 each application separately. In some applications, however, this single means
648 648 of configuration is a problem. This is particularly true of embedded software,
649 649 where there's no filesystem to read a configuration file from, and also in
650 650 applications where a radically different choice of keybindings is needed to
651 651 emulate a legacy keyboard interface. To cater for such cases, the
652 652 \fBgl_configure_getline()\fR function allows the application to control where
653 653 configuration information is read from.
654 654 .sp
655 655 .LP
656 656 The \fBgl_configure_getline()\fR function allows the configuration commands
657 657 that would normally be read from a user's \fB~/.teclarc\fR file, to be read
658 658 from any or none of, a string, an application specific configuration file,
659 659 and/or a user-specific configuration file. If this function is called before
660 660 the first call to \fBgl_get_line()\fR, the default behavior of reading
661 661 \fB~/.teclarc\fR on the first call to \fBgl_get_line()\fR is disabled, so all
662 662 configurations must be achieved using the configuration sources specified with
663 663 this function.
664 664 .sp
665 665 .LP
↓ open down ↓ |
627 lines elided |
↑ open up ↑ |
666 666 If \fIapp_string\fR != \fINULL\fR, then it is interpreted as a string
667 667 containing one or more configuration commands, separated from each other in the
668 668 string by embedded newline characters. If \fIapp_file\fR != \fINULL\fR then it
669 669 is interpreted as the full pathname of an application-specific configuration
670 670 file. If user_file != \fINULL\fR then it is interpreted as the full path name
671 671 of a user-specific configuration file, such as \fB~/.teclarc\fR. For example,
672 672 in the call
673 673 .sp
674 674 .in +2
675 675 .nf
676 -gl_configure_getline(gl, "edit-mode vi \n nobeep",
676 +gl_configure_getline(gl, "edit-mode vi \en nobeep",
677 677 "/usr/share/myapp/teclarc", "~/.teclarc");
678 678 .fi
679 679 .in -2
680 680
681 681 .sp
682 682 .LP
683 683 The \fIapp_string\fR argument causes the calling application to start in
684 684 \fBvi\fR(1) edit-mode, instead of the default \fBemacs\fR mode, and turns off
685 685 the use of the terminal bell by the library. It then attempts to read
686 686 system-wide configuration commands from an optional file called
687 687 \fB/usr/share/myapp/teclarc\fR, then finally reads user-specific configuration
688 688 commands from an optional \fB\&.teclarc\fR file in the user's home directory.
689 689 Note that the arguments are listed in ascending order of priority, with the
690 690 contents of \fIapp_string\fR being potentially over riden by commands in
691 691 \fIapp_file\fR, and commands in \fIapp_file\fR potentially being overriden by
692 692 commands in \fIuser_file\fR.
693 693 .sp
694 694 .LP
695 695 You can call this function as many times as needed, the results being
696 696 cumulative, but note that copies of any file names specified with the
697 697 \fIapp_file\fR and \fIuser_file\fR arguments are recorded internally for
698 698 subsequent use by the read-init-files key-binding function, so if you plan to
699 699 call this function multiple times, be sure that the last call specifies the
700 700 filenames that you want re-read when the user requests that the configuration
701 701 files be re-read.
702 702 .sp
703 703 .LP
704 704 Individual key sequences can also be bound and unbound using the
705 705 \fBgl_bind_keyseq()\fR function. The \fIorigin\fR argument specifies the
706 706 priority of the binding, according to whom it is being established for, and
707 707 must be one of the following two values.
708 708 .sp
709 709 .ne 2
710 710 .na
711 711 \fB\fBGL_USER_KEY\fR\fR
712 712 .ad
713 713 .RS 15n
714 714 The user requested this key-binding.
715 715 .RE
716 716
717 717 .sp
718 718 .ne 2
719 719 .na
720 720 \fB\fBGL_APP_KEY\fR\fR
721 721 .ad
722 722 .RS 15n
723 723 This is a default binding set by the application.
724 724 .RE
725 725
726 726 .sp
727 727 .LP
728 728 When both user and application bindings for a given key sequence have been
729 729 specified, the user binding takes precedence. The application's binding is
730 730 subsequently reinstated if the user's binding is later unbound with either
731 731 another call to this function, or a call to \fBgl_configure_getline()\fR.
732 732 .sp
733 733 .LP
734 734 The \fIkeyseq\fR argument specifies the key sequence to be bound or unbound,
735 735 and is expressed in the same way as in a \fB~/.teclarc\fR configuration file.
736 736 The \fIaction\fR argument must either be a string containing the name of the
737 737 action to bind the key sequence to, or it must be \fINULL\fR or \fB""\fR to
738 738 unbind the key sequence.
739 739 .SS "Customized Word Completion"
740 740 .sp
741 741 .LP
742 742 If in your application you would like to have TAB completion complete other
743 743 things in addition to or instead of filenames, you can arrange this by
744 744 registering an alternate completion callback function with a call to the
745 745 \fBgl_customize_completion()\fR function.
746 746 .sp
747 747 .LP
748 748 The \fIdata\fR argument provides a way for your application to pass arbitrary,
749 749 application-specific information to the callback function. This is passed to
750 750 the callback every time that it is called. It might for example point to the
751 751 symbol table from which possible completions are to be sought. The
752 752 \fImatch_fn\fR argument specifies the callback function to be called. The
753 753 \fICplMatchFn\fR function type is defined in <\fBlibtecla.h\fR>, as is a
754 754 \fBCPL_MATCH_FN()\fR macro that you can use to declare and prototype callback
755 755 functions. The declaration and responsibilities of callback functions are
756 756 described in depth on the \fBcpl_complete_word\fR(3TECLA) manual page.
757 757 .sp
758 758 .LP
759 759 The callback function is responsible for looking backwards in the input line
760 760 from the point at which the user pressed TAB, to find the start of the word
761 761 being completed. It then must lookup possible completions of this word, and
762 762 record them one by one in the \fBWordCompletion\fR object that is passed to it
763 763 as an argument, by calling the \fBcpl_add_completion()\fR function. If the
764 764 callback function wants to provide filename completion in addition to its own
765 765 specific completions, it has the option of itself calling the builtin filename
766 766 completion callback. This also is documented on the
767 767 \fBcpl_complete_word\fR(3TECLA) manual page.
768 768 .sp
769 769 .LP
770 770 If you would like \fBgl_get_line()\fR to return the current input line when a
771 771 successful completion is been made, you can arrange this when you call
772 772 \fBcpl_add_completion()\fR by making the last character of the continuation
773 773 suffix a newline character. The input line will be updated to display the
774 774 completion, together with any contiuation suffix up to the newline character,
775 775 and \fBgl_get_line()\fR will return this input line.
776 776 .sp
777 777 .LP
778 778 If your callback function needs to write something to the terminal, it must
779 779 call \fBgl_normal_io()\fR before doing so. This will start a new line after the
780 780 input line that is currently being edited, reinstate normal terminal I/O, and
781 781 notify \fBgl_get_line()\fR that the input line will need to be redrawn when the
782 782 callback returns.
783 783 .SS "Adding Completion Actions"
784 784 .sp
785 785 .LP
786 786 In the previous section the ability to customize the behavior of the only
787 787 default completion action, complete-word, was described. In this section the
788 788 ability to install additional action functions, so that different types of word
789 789 completion can be bound to different key sequences, is described. This is
790 790 achieved by using the \fBgl_completion_action()\fR function.
791 791 .sp
792 792 .LP
793 793 The \fIdata\fR and \fImatch_fn\fR arguments are as described on the
794 794 \fBcpl_complete_word\fR(3TECLA) manual page, and specify the callback function
795 795 that should be invoked to identify possible completions. The \fIlist_only\fR
796 796 argument determines whether the action that is being defined should attempt to
797 797 complete the word as far as possible in the input line before displaying any
798 798 possible ambiguous completions, or whether it should simply display the list of
799 799 possible completions without touching the input line. The former option is
800 800 selected by specifying a value of 0, and the latter by specifying a value of 1.
801 801 The \fIname\fR argument specifies the name by which configuration files and
802 802 future invocations of this function should refer to the action. This must
803 803 either be the name of an existing completion action to be changed, or be a new
804 804 unused name for a new action. Finally, the \fIkeyseq\fR argument specifies the
805 805 default key sequence to bind the action to. If this is \fINULL\fR, no new key
806 806 sequence will be bound to the action.
807 807 .sp
808 808 .LP
809 809 Beware that in order for the user to be able to change the key sequence that is
810 810 bound to actions that are installed in this manner, you shouldcall
811 811 \fBgl_completion_action()\fR to install a given action for the first time
812 812 between calling \fBnew_GetLine()\fR and the first call to \fBgl_get_line()\fR.
813 813 Otherwise, when the user's configuration file is read on the first call to
814 814 \fBgl_get_line()\fR, the name of the your additional action will not be known,
815 815 and any reference to it in the configuration file will generate an error.
816 816 .sp
817 817 .LP
818 818 As discussed for \fBgl_customize_completion()\fR, if your callback function
819 819 needs to write anything to the terminal, it must call \fBgl_normal_io()\fR
820 820 before doing so.
821 821 .SS "Defining Custom Actions"
822 822 .sp
823 823 .LP
824 824 Although the built-in key-binding actions are sufficient for the needs of most
825 825 applications, occasionally a specialized application may need to define one or
826 826 more custom actions, bound to application-specific key sequences. For example,
827 827 a sales application would benefit from having a key sequence that displayed the
828 828 part name that corresponded to a part number preceding the cursor. Such a
829 829 feature is clearly beyond the scope of the built-in action functions. So for
830 830 such special cases, the \fBgl_register_action()\fR function is provided.
831 831 .sp
832 832 .LP
833 833 The \fBgl_register_action()\fR function lets the application register an
834 834 external function, \fIfn\fR, that will thereafter be called whenever either the
835 835 specified key sequence, \fIkeyseq\fR, is entered by the user, or the user
836 836 enters any other key sequence that the user subsequently binds to the specified
837 837 action name, \fIname\fR, in their configuration file. The \fIdata\fR argument
838 838 can be a pointer to anything that the application wants to have passed to the
839 839 action function, \fIfn\fR, whenever that function is invoked.
840 840 .sp
841 841 .LP
842 842 The action function, \fIfn\fR, should be declared using the
843 843 \fBGL_ACTION_FN()\fR macro, which is defined in <\fBlibtecla.h\fR>.
844 844 .sp
845 845 .in +2
846 846 .nf
847 847 #define GL_ACTION_FN(fn) GlAfterAction (fn)(GetLine *gl, \e
848 848 void *data, int count, size_t curpos, \e
849 849 const char *line)
850 850 .fi
851 851 .in -2
852 852
853 853 .sp
854 854 .LP
855 855 The \fIgl\fR and \fIdata\fR arguments are those that were previously passed to
856 856 \fBgl_register_action()\fR when the action function was registered. The
857 857 \fIcount\fR argument is a numeric argument which the user has the option of
858 858 entering using the digit-argument action, before invoking the action. If the
859 859 user does not enter a number, then the \fIcount\fR argument is set to 1.
860 860 Nominally this argument is interpreted as a repeat count, meaning that the
861 861 action should be repeated that many times. In practice however, for some
862 862 actions a repeat count makes little sense. In such cases, actions can either
863 863 simply ignore the \fIcount\fR argument, or use its value for a different
864 864 purpose.
865 865 .sp
866 866 .LP
867 867 A copy of the current input line is passed in the read-only \fIline\fR
868 868 argument. The current cursor position within this string is given by the index
869 869 contained in the \fIcurpos\fR argument. Note that direct manipulation of the
870 870 input line and the cursor position is not permitted because the rules dictated
871 871 by various modes (such as \fBvi\fR mode versus \fBemacs\fR mode, no-echo mode,
872 872 and insert mode versus overstrike mode) make it too complex for an application
873 873 writer to write a conforming editing action, as well as constrain future
874 874 changes to the internals of \fBgl_get_line()\fR. A potential solution to this
875 875 dilemma would be to allow the action function to edit the line using the
876 876 existing editing actions. This is currently under consideration.
877 877 .sp
878 878 .LP
879 879 If the action function wishes to write text to the terminal without this
880 880 getting mixed up with the displayed text of the input line, or read from the
881 881 terminal without having to handle raw terminal I/O, then before doing either of
882 882 these operations, it must temporarily suspend line editing by calling the
883 883 \fBgl_normal_io()\fR function. This function flushes any pending output to the
884 884 terminal, moves the cursor to the start of the line that follows the last
885 885 terminal line of the input line, then restores the terminal to a state that is
886 886 suitable for use with the C \fBstdio\fR facilities. The latter includes such
887 887 things as restoring the normal mapping of \en to \er\en, and, when in server
888 888 mode, restoring the normal blocking form of terminal I/O. Having called this
889 889 function, the action function can read from and write to the terminal without
890 890 the fear of creating a mess. It is not necessary for the action function to
891 891 restore the original editing environment before it returns. This is done
892 892 automatically by \fBgl_get_line()\fR after the action function returns. The
893 893 following is a simple example of an action function which writes the sentence
894 894 "Hello world" on a new terminal line after the line being edited. When this
895 895 function returns, the input line is redrawn on the line that follows the "Hello
896 896 world" line, and line editing resumes.
897 897 .sp
898 898 .in +2
899 899 .nf
900 900 static GL_ACTION_FN(say_hello_fn)
901 901 {
902 902 if(gl_normal_io(gl)) /* Temporarily suspend editing */
903 903 return GLA_ABORT;
904 904 printf("Hello world\en");
905 905 return GLA_CONTINUE;
906 906 }
907 907 .fi
908 908 .in -2
909 909
910 910 .sp
911 911 .LP
912 912 Action functions must return one of the following values, to tell
913 913 \fBgl_get_line()\fR how to proceed.
914 914 .sp
915 915 .ne 2
916 916 .na
917 917 \fB\fBGLA_ABORT\fR\fR
918 918 .ad
919 919 .RS 16n
920 920 Cause \fBgl_get_line()\fR to return \fINULL\fR.
921 921 .RE
922 922
923 923 .sp
924 924 .ne 2
925 925 .na
926 926 \fB\fBGLA_RETURN\fR\fR
927 927 .ad
928 928 .RS 16n
929 929 Cause \fBgl_get_line()\fR to return the completed input line
930 930 .RE
931 931
932 932 .sp
933 933 .ne 2
934 934 .na
935 935 \fB\fBGLA_CONTINUE\fR\fR
936 936 .ad
937 937 .RS 16n
938 938 Resume command-line editing.
939 939 .RE
940 940
941 941 .sp
942 942 .LP
943 943 Note that the \fIname\fR argument of \fBgl_register_action()\fR specifies the
944 944 name by which a user can refer to the action in their configuration file. This
945 945 allows them to re-bind the action to an alternate key-sequence. In order for
946 946 this to work, it is necessary to call \fBgl_register_action()\fR between
947 947 calling \fBnew_GetLine()\fR and the first call to \fBgl_get_line()\fR.
948 948 .SS "History Files"
949 949 .sp
950 950 .LP
951 951 To save the contents of the history buffer before quitting your application and
952 952 subsequently restore them when you next start the application, the
953 953 \fBgl_save_history()\fR and \fBgl_load_history()\fR functions are provided.
954 954 .sp
955 955 .LP
956 956 The \fIfilename\fR argument specifies the name to give the history file when
957 957 saving, or the name of an existing history file, when loading. This may contain
958 958 home directory and environment variable expressions, such as
959 959 \fB~/.myapp_history\fR or \fB$HOME/.myapp_history\fR.
960 960 .sp
961 961 .LP
962 962 Along with each history line, additional information about it, such as its
963 963 nesting level and when it was entered by the user, is recorded as a comment
964 964 preceding the line in the history file. Writing this as a comment allows the
965 965 history file to double as a command file, just in case you wish to replay a
966 966 whole session using it. Since comment prefixes differ in different languages,
967 967 the comment argument is provided for specifying the comment prefix. For
968 968 example, if your application were a UNIX shell, such as the Bourne shell, you
969 969 would specify "#" here. Whatever you choose for the comment character, you must
970 970 specify the same prefix to \fBgl_load_history()\fR that you used when you
971 971 called \fBgl_save_history()\fR to write the history file.
972 972 .sp
973 973 .LP
974 974 The \fImax_lines\fR argument must be either -1 to specify that all lines in the
975 975 history list be saved, or a positive number specifying a ceiling on how many of
976 976 the most recent lines should be saved.
977 977 .sp
978 978 .LP
979 979 Both fuctions return non-zero on error, after writing an error message to
980 980 \fBstderr\fR. Note that \fBgl_load_history()\fR does not consider the
981 981 non-existence of a file to be an error.
982 982 .SS "Multiple History Lists"
983 983 .sp
984 984 .LP
985 985 If your application uses a single \fBGetLine\fR object for entering many
986 986 different types of input lines, you might want \fBgl_get_line()\fR to
987 987 distinguish the different types of lines in the history list, and only recall
988 988 lines that match the current type of line. To support this requirement,
989 989 \fBgl_get_line()\fR marks lines being recorded in the history list with an
990 990 integer identifier chosen by the application. Initially this identifier is set
991 991 to 0 by \fBnew_GetLine()\fR, but it can be changed subsequently by calling
992 992 \fBgl_group_history()\fR.
993 993 .sp
994 994 .LP
995 995 The integer identifier ID can be any number chosen by the application, but note
996 996 that \fBgl_save_history()\fR and \fBgl_load_history()\fR preserve the
997 997 association between identifiers and historical input lines between program
998 998 invocations, so you should choose fixed identifiers for the different types of
999 999 input line used by your application.
1000 1000 .sp
1001 1001 .LP
1002 1002 Whenever \fBgl_get_line()\fR appends a new input line to the history list, the
1003 1003 current history identifier is recorded with it, and when it is asked to recall
1004 1004 a historical input line, it only recalls lines that are marked with the current
1005 1005 identifier.
1006 1006 .SS "Displaying History"
1007 1007 .sp
1008 1008 .LP
1009 1009 The history list can be displayed by calling \fBgl_show_history()\fR. This
1010 1010 function displays the current contents of the history list to the \fBstdio\fR
1011 1011 output stream \fIfp\fR. If the \fImax_lines\fR argument is greater than or
1012 1012 equal to zero, then no more than this number of the most recent lines will be
1013 1013 displayed. If the \fIall_groups\fR argument is non-zero, lines from all history
1014 1014 groups are displayed. Otherwise only those of the currently selected history
1015 1015 group are displayed. The format string argument, \fIfmt\fR, determines how the
1016 1016 line is displayed. This can contain arbitrary characters which are written
1017 1017 verbatim, interleaved with any of the following format directives:
1018 1018 .sp
1019 1019 .ne 2
1020 1020 .na
1021 1021 \fB\fB%D\fR\fR
1022 1022 .ad
1023 1023 .RS 6n
1024 1024 The date on which the line was originally entered, formatted like 2001-11-20.
1025 1025 .RE
1026 1026
1027 1027 .sp
1028 1028 .ne 2
1029 1029 .na
1030 1030 \fB\fB%T\fR\fR
1031 1031 .ad
1032 1032 .RS 6n
1033 1033 The time of day when the line was entered, formatted like 23:59:59.
1034 1034 .RE
1035 1035
1036 1036 .sp
1037 1037 .ne 2
1038 1038 .na
1039 1039 \fB\fB%N\fR\fR
1040 1040 .ad
1041 1041 .RS 6n
1042 1042 The sequential entry number of the line in the history buffer.
1043 1043 .RE
1044 1044
1045 1045 .sp
1046 1046 .ne 2
1047 1047 .na
1048 1048 \fB\fB%G\fR\fR
1049 1049 .ad
1050 1050 .RS 6n
1051 1051 The number of the history group which the line belongs to.
1052 1052 .RE
1053 1053
1054 1054 .sp
1055 1055 .ne 2
1056 1056 .na
1057 1057 \fB\fB%%\fR\fR
1058 1058 .ad
1059 1059 .RS 6n
1060 1060 A literal % character.
1061 1061 .RE
1062 1062
1063 1063 .sp
1064 1064 .ne 2
1065 1065 .na
1066 1066 \fB\fB%H\fR\fR
1067 1067 .ad
1068 1068 .RS 6n
1069 1069 The history line itself.
1070 1070 .RE
1071 1071
1072 1072 .sp
1073 1073 .LP
1074 1074 Thus a format string like "%D %T %H0" would output something like:
1075 1075 .sp
1076 1076 .in +2
1077 1077 .nf
1078 1078 2001-11-20 10:23:34 Hello world
1079 1079 .fi
1080 1080 .in -2
1081 1081
1082 1082 .sp
1083 1083 .LP
1084 1084 Note the inclusion of an explicit newline character in the format string.
1085 1085 .SS "Looking Up History"
1086 1086 .sp
1087 1087 .LP
1088 1088 The \fBgl_lookup_history()\fR function allows the calling application to look
1089 1089 up lines in the history list.
1090 1090 .sp
1091 1091 .LP
1092 1092 The \fIid\fR argument indicates which line to look up, where the first line
1093 1093 that was entered in the history list after \fBnew_GetLine()\fR was called is
1094 1094 denoted by 0, and subsequently entered lines are denoted with successively
1095 1095 higher numbers. Note that the range of lines currently preserved in the history
1096 1096 list can be queried by calling the \fBgl_range_of_history()\fR function. If the
1097 1097 requested line is in the history list, the details of the line are recorded in
1098 1098 the variable pointed to by the \fIhline\fR argument, and 1 is returned.
1099 1099 Otherwise 0 is returned, and the variable pointed to by \fIhline\fR is left
1100 1100 unchanged.
1101 1101 .sp
1102 1102 .LP
1103 1103 Beware that the string returned in \fIhline\fR->\fIline\fR is part of the
1104 1104 history buffer, so it must not be modified by the caller, and will be recycled
1105 1105 on the next call to any function that takes \fIgl\fR as its argument. Therefore
1106 1106 you should make a private copy of this string if you need to keep it.
1107 1107 .SS "Manual History Archival"
1108 1108 .sp
1109 1109 .LP
1110 1110 By default, whenever a line is entered by the user, it is automatically
1111 1111 appended to the history list, just before \fBgl_get_line()\fR returns the line
1112 1112 to the caller. This is convenient for the majority of applications, but there
1113 1113 are also applications that need finer-grained control over what gets added to
1114 1114 the history list. In such cases, the automatic addition of entered lines to the
1115 1115 history list can be turned off by calling the \fBgl_automatic_history()\fR
1116 1116 function.
1117 1117 .sp
1118 1118 .LP
1119 1119 If this function is called with its \fIenable\fR argument set to 0,
1120 1120 \fBgl_get_line()\fR will not automatically archive subsequently entered lines.
1121 1121 Automatic archiving can be reenabled at a later time by calling this function
1122 1122 again, with its \fIenable\fR argument set to 1. While automatic history
1123 1123 archiving is disabled, the calling application can use the
1124 1124 \fBgl_append_history()\fR to append lines to the history list as needed.
1125 1125 .sp
1126 1126 .LP
1127 1127 The \fIline\fR argument specifies the line to be added to the history list.
1128 1128 This must be a normal '\e0 ' terminated string. If this string contains any
1129 1129 newline characters, the line that gets archived in the history list will be
1130 1130 terminated by the first of these. Otherwise it will be terminated by the '\e0 '
1131 1131 terminator. If the line is longer than the maximum input line length that was
1132 1132 specified when \fBnew_GetLine()\fR was called, it will be truncated to the
1133 1133 actual \fBgl_get_line()\fR line length when the line is recalled.
1134 1134 .sp
1135 1135 .LP
1136 1136 If successful, \fBgl_append_history()\fR returns 0. Otherwise it returns
1137 1137 non-zero and sets \fBerrno\fR to one of the following values.
1138 1138 .sp
1139 1139 .ne 2
1140 1140 .na
1141 1141 \fB\fBEINVAL\fR\fR
1142 1142 .ad
1143 1143 .RS 10n
1144 1144 One of the arguments passed to \fBgl_append_history()\fR was \fINULL\fR.
1145 1145 .RE
1146 1146
1147 1147 .sp
1148 1148 .ne 2
1149 1149 .na
1150 1150 \fB\fBENOMEM\fR\fR
1151 1151 .ad
1152 1152 .RS 10n
1153 1153 The specified line was longer than the allocated size of the history buffer (as
1154 1154 specified when \fBnew_GetLine()\fR was called), so it could not be archived.
1155 1155 .RE
1156 1156
1157 1157 .sp
1158 1158 .LP
1159 1159 A textual description of the error can optionally be obtained by calling
1160 1160 \fBgl_error_message()\fR. Note that after such an error, the history list
1161 1161 remains in a valid state to receive new history lines, so there is little harm
1162 1162 in simply ignoring the return status of \fBgl_append_history()\fR.
1163 1163 .SS "Miscellaneous History Configuration"
1164 1164 .sp
1165 1165 .LP
1166 1166 If you wish to change the size of the history buffer that was originally
1167 1167 specified in the call to \fBnew_GetLine()\fR, you can do so with the
1168 1168 \fBgl_resize_history()\fR function.
1169 1169 .sp
1170 1170 .LP
1171 1171 The \fIhistlen\fR argument specifies the new size in bytes, and if you specify
1172 1172 this as 0, the buffer will be deleted.
1173 1173 .sp
1174 1174 .LP
1175 1175 As mentioned in the discussion of \fBnew_GetLine()\fR, the number of lines that
1176 1176 can be stored in the history buffer, depends on the lengths of the individual
1177 1177 lines. For example, a 1000 byte buffer could equally store 10 lines of average
1178 1178 length 100 bytes, or 20 lines of average length 50 bytes. Although the buffer
1179 1179 is never expanded when new lines are added, a list of pointers into the buffer
1180 1180 does get expanded when needed to accomodate the number of lines currently
1181 1181 stored in the buffer. To place an upper limit on the number of lines in the
1182 1182 buffer, and thus a ceiling on the amount of memory used in this list, you can
1183 1183 call the \fBgl_limit_history()\fR function.
1184 1184 .sp
1185 1185 .LP
1186 1186 The \fImax_lines\fR should either be a positive number >= 0, specifying an
1187 1187 upper limit on the number of lines in the buffer, or be -1 to cancel any
1188 1188 previously specified limit. When a limit is in effect, only the \fImax_lines\fR
1189 1189 most recently appended lines are kept in the buffer. Older lines are discarded.
1190 1190 .sp
1191 1191 .LP
1192 1192 To discard lines from the history buffer, use the \fBgl_clear_history()\fR
1193 1193 function.
1194 1194 .sp
1195 1195 .LP
1196 1196 The \fIall_groups\fR argument tells the function whether to delete just the
1197 1197 lines associated with the current history group (see \fBgl_group_history()\fR)
1198 1198 or all historical lines in the buffer.
1199 1199 .sp
1200 1200 .LP
1201 1201 The \fBgl_toggle_history()\fR function allows you to toggle history on and off
1202 1202 without losing the current contents of the history list.
1203 1203 .sp
1204 1204 .LP
1205 1205 Setting the \fIenable\fR argument to 0 turns off the history mechanism, and
1206 1206 setting it to 1 turns it back on. When history is turned off, no new lines will
1207 1207 be added to the history list, and history lookup key-bindings will act as
1208 1208 though there is nothing in the history buffer.
1209 1209 .SS "Querying History Information"
1210 1210 .sp
1211 1211 .LP
1212 1212 The configured state of the history list can be queried with the
1213 1213 \fBgl_history_state()\fR function. On return, the status information is
1214 1214 recorded in the variable pointed to by the \fIstate\fR argument.
1215 1215 .sp
1216 1216 .LP
1217 1217 The \fBgl_range_of_history()\fR function returns the number and range of lines
1218 1218 in the history list. The return values are recorded in the variable pointed to
1219 1219 by the range argument. If the \fInlines\fR member of this structure is greater
1220 1220 than zero, then the oldest and newest members report the range of lines in the
1221 1221 list, and \fInewest\fR=\fIoldest\fR+\fInlines\fR-1. Otherwise they are both
1222 1222 zero.
1223 1223 .sp
1224 1224 .LP
1225 1225 The \fBgl_size_of_history()\fR function returns the total size of the history
1226 1226 buffer and the amount of the buffer that is currently occupied.
1227 1227 .sp
1228 1228 .LP
1229 1229 On return, the size information is recorded in the variable pointed to by the
1230 1230 \fIsize\fR argument.
1231 1231 .SS "Changing Terminals"
1232 1232 .sp
1233 1233 .LP
1234 1234 The \fBnew_GetLine()\fR constructor function assumes that input is to be read
1235 1235 from \fBstdin\fR and output written to \fBstdout\fR. The following function
1236 1236 allows you to switch to different input and output streams.
1237 1237 .sp
1238 1238 .LP
1239 1239 The \fIgl\fR argument is the object that was returned by \fBnew_GetLine()\fR.
1240 1240 The \fIinput_fp\fR argument specifies the stream to read from, and
1241 1241 \fIoutput_fp\fR specifies the stream to be written to. Only if both of these
1242 1242 refer to a terminal, will interactive terminal input be enabled. Otherwise
1243 1243 \fBgl_get_line()\fR will simply call \fBfgets()\fR to read command input. If
1244 1244 both streams refer to a terminal, then they must refer to the same terminal,
1245 1245 and the type of this terminal must be specified with the \fIterm\fR argument.
1246 1246 The value of the \fIterm\fR argument is looked up in the terminal information
1247 1247 database (\fBterminfo\fR or \fBtermcap\fR), in order to determine which special
1248 1248 control sequences are needed to control various aspects of the terminal.
1249 1249 \fBnew_GetLine()\fR for example, passes the return value of
1250 1250 \fBgetenv\fR("TERM") in this argument. Note that if one or both of
1251 1251 \fIinput_fp\fR and \fIoutput_fp\fR do not refer to a terminal, then it is legal
1252 1252 to pass \fINULL\fR instead of a terminal type.
1253 1253 .sp
1254 1254 .LP
1255 1255 Note that if you want to pass file descriptors to \fBgl_change_terminal()\fR,
1256 1256 you can do this by creating \fBstdio\fR stream wrappers using the POSIX
1257 1257 \fBfdopen\fR(3C) function.
1258 1258 .SS "External Event Handling"
1259 1259 .sp
1260 1260 .LP
1261 1261 By default, \fBgl_get_line()\fR does not return until either a complete input
1262 1262 line has been entered by the user, or an error occurs. In programs that need to
1263 1263 watch for I/O from other sources than the terminal, there are two options.
1264 1264 .RS +4
1265 1265 .TP
1266 1266 .ie t \(bu
1267 1267 .el o
1268 1268 Use the functions described in the \fBgl_io_mode\fR(3TECLA) manual page to
1269 1269 switch \fBgl_get_line()\fR into non-blocking server mode. In this mode,
1270 1270 \fBgl_get_line()\fR becomes a non-blocking, incremental line-editing function
1271 1271 that can safely be called from an external event loop. Although this is a very
1272 1272 versatile method, it involves taking on some responsibilities that are normally
1273 1273 performed behind the scenes by \fBgl_get_line()\fR.
1274 1274 .RE
1275 1275 .RS +4
1276 1276 .TP
1277 1277 .ie t \(bu
1278 1278 .el o
1279 1279 While \fBgl_get_line()\fR is waiting for keyboard input from the user, you can
1280 1280 ask it to also watch for activity on arbitrary file descriptors, such as
1281 1281 network sockets or pipes, and have it call functions of your choosing when
1282 1282 activity is seen. This works on any system that has the select system call,
1283 1283 which is most, if not all flavors of UNIX.
1284 1284 .RE
1285 1285 .sp
1286 1286 .LP
1287 1287 Registering a file descriptor to be watched by \fBgl_get_line()\fR involves
1288 1288 calling the \fBgl_watch_fd()\fR function. If this returns non-zero, then it
1289 1289 means that either your arguments are invalid, or that this facility is not
1290 1290 supported on the host system.
1291 1291 .sp
1292 1292 .LP
1293 1293 The \fIfd\fR argument is the file descriptor to be watched. The event argument
1294 1294 specifies what type of activity is of interest, chosen from the following
1295 1295 enumerated values:
1296 1296 .sp
1297 1297 .ne 2
1298 1298 .na
1299 1299 \fB\fBGLFD_READ\fR\fR
1300 1300 .ad
1301 1301 .RS 15n
1302 1302 Watch for the arrival of data to be read.
1303 1303 .RE
1304 1304
1305 1305 .sp
1306 1306 .ne 2
1307 1307 .na
1308 1308 \fB\fBGLFD_WRITE\fR\fR
1309 1309 .ad
1310 1310 .RS 15n
1311 1311 Watch for the ability to write to the file descriptor without blocking.
1312 1312 .RE
1313 1313
1314 1314 .sp
1315 1315 .ne 2
1316 1316 .na
1317 1317 \fB\fBGLFD_URGENT\fR\fR
1318 1318 .ad
1319 1319 .RS 15n
1320 1320 Watch for the arrival of urgent out-of-band data on the file descriptor.
1321 1321 .RE
1322 1322
1323 1323 .sp
1324 1324 .LP
1325 1325 The \fIcallback\fR argument is the function to call when the selected activity
1326 1326 is seen. It should be defined with the following macro, which is defined in
1327 1327 libtecla.h.
1328 1328 .sp
1329 1329 .in +2
1330 1330 .nf
1331 1331 #define GL_FD_EVENT_FN(fn) GlFdStatus (fn)(GetLine *gl, \
1332 1332 void *data, int fd, GlFdEvent event)
1333 1333 .fi
1334 1334 .in -2
1335 1335
1336 1336 .sp
1337 1337 .LP
1338 1338 The data argument of the \fBgl_watch_fd()\fR function is passed to the callback
1339 1339 function for its own use, and can point to anything you like, including
1340 1340 \fINULL\fR. The file descriptor and the event argument are also passed to the
1341 1341 callback function, and this potentially allows the same callback function to be
1342 1342 registered to more than one type of event and/or more than one file descriptor.
1343 1343 The return value of the callback function should be one of the following
1344 1344 values.
1345 1345 .sp
1346 1346 .ne 2
1347 1347 .na
1348 1348 \fB\fBGLFD_ABORT\fR\fR
1349 1349 .ad
1350 1350 .RS 17n
1351 1351 Tell \fBgl_get_line()\fR to abort. When this happens, \fBgl_get_line()\fR
1352 1352 returns \fINULL\fR, and a following call to \fBgl_return_status()\fR will
1353 1353 return \fBGLR_FDABORT\fR. Note that if the application needs \fBerrno\fR always
1354 1354 to have a meaningful value when \fBgl_get_line()\fR returns \fINULL\fR, the
1355 1355 callback function should set \fBerrno\fR appropriately.
1356 1356 .RE
1357 1357
1358 1358 .sp
1359 1359 .ne 2
1360 1360 .na
1361 1361 \fB\fBGLFD_REFRESH\fR\fR
1362 1362 .ad
1363 1363 .RS 17n
1364 1364 Redraw the input line then continue waiting for input. Return this if your
1365 1365 callback wrote to the terminal.
1366 1366 .RE
1367 1367
1368 1368 .sp
1369 1369 .ne 2
1370 1370 .na
1371 1371 \fB\fBGLFD_CONTINUE\fR\fR
1372 1372 .ad
1373 1373 .RS 17n
1374 1374 Continue to wait for input, without redrawing the line.
1375 1375 .RE
1376 1376
1377 1377 .sp
1378 1378 .LP
1379 1379 Note that before calling the callback, \fBgl_get_line()\fR blocks most signals
1380 1380 and leaves its own signal handlers installed, so if you need to catch a
1381 1381 particular signal you will need to both temporarily install your own signal
1382 1382 handler, and unblock the signal. Be sure to re-block the signal (if it was
1383 1383 originally blocked) and reinstate the original signal handler, if any, before
1384 1384 returning.
1385 1385 .sp
1386 1386 .LP
1387 1387 Your callback should not try to read from the terminal, which is left in raw
1388 1388 mode as far as input is concerned. You can write to the terminal as usual,
1389 1389 since features like conversion of newline to carriage-return/linefeed are
1390 1390 re-enabled while the callback is running. If your callback function does write
1391 1391 to the terminal, be sure to output a newline first, and when your callback
1392 1392 returns, tell \fBgl_get_line()\fR that the input line needs to be redrawn, by
1393 1393 returning the \fBGLFD_REFRESH\fR status code.
1394 1394 .sp
1395 1395 .LP
1396 1396 To remove a callback function that you previously registered for a given file
1397 1397 descriptor and event, simply call \fBgl_watch_fd()\fR with the same \fIfd\fR
1398 1398 and \fIevent\fR arguments, but with a \fIcallback\fR argument of 0. The
1399 1399 \fIdata\fR argument is ignored in this case.
1400 1400 .SS "Setting An Inactivity Timeout"
1401 1401 .sp
1402 1402 .LP
1403 1403 The \fBgl_inactivity_timeout()\fR function can be used to set or cancel an
1404 1404 inactivity timeout. Inactivity in this case refers both to keyboard input, and
1405 1405 to I/O on any file descriptors registered by prior and subsequent calls to
1406 1406 \fBgl_watch_fd()\fR.
1407 1407 .sp
1408 1408 .LP
1409 1409 The timeout is specified in the form of an integral number of seconds and an
1410 1410 integral number of nanoseconds, specified by the \fIsec\fR and \fInsec\fR
1411 1411 arguments, respectively. Subsequently, whenever no activity is seen for this
1412 1412 time period, the function specified by the \fIcallback\fR argument is called.
1413 1413 The \fIdata\fR argument of \fBgl_inactivity_timeout()\fR is passed to this
1414 1414 callback function whenever it is invoked, and can thus be used to pass
1415 1415 arbitrary application-specific information to the callback. The following macro
1416 1416 is provided in <\fBlibtecla.h\fR> for applications to use to declare and
1417 1417 prototype timeout callback functions.
1418 1418 .sp
1419 1419 .in +2
1420 1420 .nf
1421 1421 #define GL_TIMEOUT_FN(fn) GlAfterTimeout (fn)(GetLine *gl, void *data)
1422 1422 .fi
1423 1423 .in -2
1424 1424
1425 1425 .sp
1426 1426 .LP
1427 1427 On returning, the application's callback is expected to return one of the
1428 1428 following enumerators to tell \fBgl_get_line()\fR how to procede after the
1429 1429 timeout has been handled by the callback.
1430 1430 .sp
1431 1431 .ne 2
1432 1432 .na
1433 1433 \fB\fBGLTO_ABORT\fR\fR
1434 1434 .ad
1435 1435 .RS 17n
1436 1436 Tell \fBgl_get_line()\fR to abort. When this happens, \fBgl_get_line()\fR will
1437 1437 return \fINULL\fR, and a following call to \fBgl_return_status()\fR will return
1438 1438 \fBGLR_TIMEOUT\fR. Note that if the application needs \fBerrno\fR always to
1439 1439 have a meaningful value when \fBgl_get_line()\fR returns \fINULL\fR, the
1440 1440 callback function should set \fBerrno\fR appropriately.
1441 1441 .RE
1442 1442
1443 1443 .sp
1444 1444 .ne 2
1445 1445 .na
1446 1446 \fB\fBGLTO_REFRESH\fR\fR
1447 1447 .ad
1448 1448 .RS 17n
1449 1449 Redraw the input line, then continue waiting for input. You should return this
1450 1450 value if your callback wrote to the terminal.
1451 1451 .RE
1452 1452
1453 1453 .sp
1454 1454 .ne 2
1455 1455 .na
1456 1456 \fB\fBGLTO_CONTINUE\fR\fR
1457 1457 .ad
1458 1458 .RS 17n
1459 1459 In normal blocking-I/O mode, continue to wait for input, without redrawing the
1460 1460 user's input line. In non-blocking server I/O mode (see
1461 1461 \fBgl_io_mode\fR(3TECLA)), \fBgl_get_line()\fR acts as though I/O blocked. This
1462 1462 means that \fBgl_get_line()\fR will immediately return \fINULL\fR, and a
1463 1463 following call to \fBgl_return_status()\fR will return \fBGLR_BLOCKED\fR.
1464 1464 .RE
1465 1465
1466 1466 .sp
1467 1467 .LP
1468 1468 Note that before calling the callback, \fBgl_get_line()\fR blocks most signals
1469 1469 and leaves its own signal handlers installed, so if you need to catch a
1470 1470 particular signal you will need to both temporarily install your own signal
1471 1471 handler and unblock the signal. Be sure to re-block the signal (if it was
1472 1472 originally blocked) and reinstate the original signal handler, if any, before
1473 1473 returning.
1474 1474 .sp
1475 1475 .LP
1476 1476 Your callback should not try to read from the terminal, which is left in raw
1477 1477 mode as far as input is concerned. You can however write to the terminal as
1478 1478 usual, since features like conversion of newline to carriage-return/linefeed
1479 1479 are re-enabled while the callback is running. If your callback function does
1480 1480 write to the terminal, be sure to output a newline first, and when your
1481 1481 callback returns, tell \fBgl_get_line()\fR that the input line needs to be
1482 1482 redrawn, by returning the \fBGLTO_REFRESH\fR status code.
1483 1483 .sp
1484 1484 .LP
1485 1485 Finally, note that although the timeout arguments include a nanosecond
1486 1486 component, few computer clocks presently have resolutions that are finer than a
1487 1487 few milliseconds, so asking for less than a few milliseconds is equivalent to
1488 1488 requesting zero seconds on many systems. If this would be a problem, you should
1489 1489 base your timeout selection on the actual resolution of the host clock (for
1490 1490 example, by calling \fBsysconf\fR(\fB_SC_CLK_TCK\fR)).
1491 1491 .sp
1492 1492 .LP
1493 1493 To turn off timeouts, simply call \fBgl_inactivity_timeout()\fR with a
1494 1494 \fIcallback\fR argument of 0. The \fIdata\fR argument is ignored in this case.
1495 1495 .SS "Signal Handling Defaults"
1496 1496 .sp
1497 1497 .LP
1498 1498 By default, the \fBgl_get_line()\fR function intercepts a number of signals.
1499 1499 This is particularly important for signals that would by default terminate the
1500 1500 process, since the terminal needs to be restored to a usable state before this
1501 1501 happens. This section describes the signals that are trapped by default and how
1502 1502 \fBgl_get_line()\fR responds to them. Changing these defaults is the topic of
1503 1503 the following section.
1504 1504 .sp
1505 1505 .LP
1506 1506 When the following subset of signals are caught, \fBgl_get_line()\fR first
1507 1507 restores the terminal settings and signal handling to how they were before
1508 1508 \fBgl_get_line()\fR was called, resends the signal to allow the calling
1509 1509 application's signal handlers to handle it, then, if the process still exists,
1510 1510 returns \fINULL\fR and sets \fBerrno\fR as specified below.
1511 1511 .sp
1512 1512 .ne 2
1513 1513 .na
1514 1514 \fB\fBSIGINT\fR\fR
1515 1515 .ad
1516 1516 .RS 11n
1517 1517 This signal is generated both by the keyboard interrupt key (usually \fB^C\fR),
1518 1518 and the keyboard break key. The \fBerrno\fR value is \fBEINTR\fR.
1519 1519 .RE
1520 1520
1521 1521 .sp
1522 1522 .ne 2
1523 1523 .na
1524 1524 \fB\fBSIGHUP\fR\fR
1525 1525 .ad
1526 1526 .RS 11n
1527 1527 This signal is generated when the controlling terminal exits. The \fBerrno\fR
1528 1528 value is \fBENOTTY\fR.
1529 1529 .RE
1530 1530
1531 1531 .sp
1532 1532 .ne 2
1533 1533 .na
1534 1534 \fB\fBSIGPIPE\fR\fR
1535 1535 .ad
1536 1536 .RS 11n
1537 1537 This signal is generated when a program attempts to write to a pipe whose
1538 1538 remote end is not being read by any process. This can happen for example if you
1539 1539 have called \fBgl_change_terminal()\fR to redirect output to a pipe hidden
1540 1540 under a pseudo terminal. The \fBerrno\fR value is \fBEPIPE\fR.
1541 1541 .RE
1542 1542
1543 1543 .sp
1544 1544 .ne 2
1545 1545 .na
1546 1546 \fB\fBSIGQUIT\fR\fR
1547 1547 .ad
1548 1548 .RS 11n
1549 1549 This signal is generated by the keyboard quit key (usually \fB^\\fR). The
1550 1550 \fBerrno\fR value is \fBEINTR\fR.
1551 1551 .RE
1552 1552
1553 1553 .sp
1554 1554 .ne 2
1555 1555 .na
1556 1556 \fB\fBSIGABRT\fR\fR
1557 1557 .ad
1558 1558 .RS 11n
1559 1559 This signal is generated by the standard C, abort function. By default it both
1560 1560 terminates the process and generates a core dump. The \fBerrno\fR value is
1561 1561 \fBEINTR\fR.
1562 1562 .RE
1563 1563
1564 1564 .sp
1565 1565 .ne 2
1566 1566 .na
1567 1567 \fB\fBSIGTERM\fR\fR
1568 1568 .ad
1569 1569 .RS 11n
1570 1570 This is the default signal that the UNIX kill command sends to processes. The
1571 1571 \fBerrno\fR value is \fBEINTR\fR.
1572 1572 .RE
1573 1573
1574 1574 .sp
1575 1575 .LP
1576 1576 Note that in the case of all of the above signals, POSIX mandates that by
1577 1577 default the process is terminated, with the addition of a core dump in the case
1578 1578 of the \fBSIGQUIT\fR signal. In other words, if the calling application does
1579 1579 not override the default handler by supplying its own signal handler, receipt
1580 1580 of the corresponding signal will terminate the application before
1581 1581 \fBgl_get_line()\fR returns.
1582 1582 .sp
1583 1583 .LP
1584 1584 If \fBgl_get_line()\fR aborts with \fBerrno\fR set to \fBEINTR\fR, you can find
1585 1585 out what signal caused it to abort, by calling the \fBgl_last_signal()\fR
1586 1586 function. This returns the numeric code (for example, \fBSIGINT\fR) of the last
1587 1587 signal that was received during the most recent call to \fBgl_get_line()\fR, or
1588 1588 -1 if no signals were received.
1589 1589 .sp
1590 1590 .LP
1591 1591 On systems that support it, when a \fBSIGWINCH\fR (window change) signal is
1592 1592 received, \fBgl_get_line()\fR queries the terminal to find out its new size,
1593 1593 redraws the current input line to accomodate the new size, then returns to
1594 1594 waiting for keyboard input from the user. Unlike other signals, this signal is
1595 1595 not resent to the application.
1596 1596 .sp
1597 1597 .LP
1598 1598 Finally, the following signals cause \fBgl_get_line()\fR to first restore the
1599 1599 terminal and signal environment to that which prevailed before
1600 1600 \fBgl_get_line()\fR was called, then resend the signal to the application. If
1601 1601 the process still exists after the signal has been delivered, then
1602 1602 \fBgl_get_line()\fR then re-establishes its own signal handlers, switches the
1603 1603 terminal back to raw mode, redisplays the input line, and goes back to awaiting
1604 1604 terminal input from the user.
1605 1605 .sp
1606 1606 .ne 2
1607 1607 .na
1608 1608 \fB\fBSIGCONT\fR\fR
1609 1609 .ad
1610 1610 .RS 13n
1611 1611 This signal is generated when a suspended process is resumed.
1612 1612 .RE
1613 1613
1614 1614 .sp
1615 1615 .ne 2
1616 1616 .na
1617 1617 \fB\fBSIGPOLL\fR\fR
1618 1618 .ad
1619 1619 .RS 13n
1620 1620 On SVR4 systems, this signal notifies the process of an asynchronous I/O event.
1621 1621 Note that under 4.3+BSD, \fBSIGIO\fR and \fBSIGPOLL\fR are the same. On other
1622 1622 systems, \fBSIGIO\fR is ignored by default, so \fBgl_get_line()\fR does not
1623 1623 trap it by default.
1624 1624 .RE
1625 1625
1626 1626 .sp
1627 1627 .ne 2
1628 1628 .na
1629 1629 \fB\fBSIGPWR\fR\fR
1630 1630 .ad
1631 1631 .RS 13n
1632 1632 This signal is generated when a power failure occurs (presumably when the
1633 1633 system is on a UPS).
1634 1634 .RE
1635 1635
1636 1636 .sp
1637 1637 .ne 2
1638 1638 .na
1639 1639 \fB\fBSIGALRM\fR\fR
1640 1640 .ad
1641 1641 .RS 13n
1642 1642 This signal is generated when a timer expires.
1643 1643 .RE
1644 1644
1645 1645 .sp
1646 1646 .ne 2
1647 1647 .na
1648 1648 \fB\fBSIGUSR1\fR\fR
1649 1649 .ad
1650 1650 .RS 13n
1651 1651 An application specific signal.
1652 1652 .RE
1653 1653
1654 1654 .sp
1655 1655 .ne 2
1656 1656 .na
1657 1657 \fB\fBSIGUSR2\fR\fR
1658 1658 .ad
1659 1659 .RS 13n
1660 1660 Another application specific signal.
1661 1661 .RE
1662 1662
1663 1663 .sp
1664 1664 .ne 2
1665 1665 .na
1666 1666 \fB\fBSIGVTALRM\fR\fR
1667 1667 .ad
1668 1668 .RS 13n
1669 1669 This signal is generated when a virtual timer expires. See \fBsetitimer\fR(2).
1670 1670 .RE
1671 1671
1672 1672 .sp
1673 1673 .ne 2
1674 1674 .na
1675 1675 \fB\fBSIGXCPU\fR\fR
1676 1676 .ad
1677 1677 .RS 13n
1678 1678 This signal is generated when a process exceeds its soft CPU time limit.
1679 1679 .RE
1680 1680
1681 1681 .sp
1682 1682 .ne 2
1683 1683 .na
1684 1684 \fB\fBSIGXFSZ\fR\fR
1685 1685 .ad
1686 1686 .RS 13n
1687 1687 This signal is generated when a process exceeds its soft file-size limit.
1688 1688 .RE
1689 1689
1690 1690 .sp
1691 1691 .ne 2
1692 1692 .na
1693 1693 \fB\fBSIGTSTP\fR\fR
1694 1694 .ad
1695 1695 .RS 13n
1696 1696 This signal is generated by the terminal suspend key, which is usually
1697 1697 \fB^Z\fR, or the delayed terminal suspend key, which is usually \fB^Y\fR.
1698 1698 .RE
1699 1699
1700 1700 .sp
1701 1701 .ne 2
1702 1702 .na
1703 1703 \fB\fBSIGTTIN\fR\fR
1704 1704 .ad
1705 1705 .RS 13n
1706 1706 This signal is generated if the program attempts to read from the terminal
1707 1707 while the program is running in the background.
1708 1708 .RE
1709 1709
1710 1710 .sp
1711 1711 .ne 2
1712 1712 .na
1713 1713 \fB\fBSIGTTOU\fR\fR
1714 1714 .ad
1715 1715 .RS 13n
1716 1716 This signal is generated if the program attempts to write to the terminal while
1717 1717 the program is running in the background.
1718 1718 .RE
1719 1719
1720 1720 .sp
1721 1721 .LP
1722 1722 Obviously not all of the above signals are supported on all systems, so code to
1723 1723 support them is conditionally compiled into the tecla library.
1724 1724 .sp
1725 1725 .LP
1726 1726 Note that if \fBSIGKILL\fR or \fBSIGPOLL\fR, which by definition cannot be
1727 1727 caught, or any of the hardware generated exception signals, such as
1728 1728 \fBSIGSEGV\fR, \fBSIGBUS\fR, and \fBSIGFPE\fR, are received and unhandled while
1729 1729 \fBgl_get_line()\fR has the terminal in raw mode, the program will be
1730 1730 terminated without the terminal having been restored to a usable state. In
1731 1731 practice, job-control shells usually reset the terminal settings when a process
1732 1732 relinquishes the controlling terminal, so this is only a problem with older
1733 1733 shells.
1734 1734 .SS "Customized Signal Handling"
1735 1735 .sp
1736 1736 .LP
1737 1737 The previous section listed the signals that \fBgl_get_line()\fR traps by
1738 1738 default, and described how it responds to them. This section describes how to
1739 1739 both add and remove signals from the list of trapped signals, and how to
1740 1740 specify how \fBgl_get_line()\fR should respond to a given signal.
1741 1741 .sp
1742 1742 .LP
1743 1743 If you do not need \fBgl_get_line()\fR to do anything in response to a signal
1744 1744 that it normally traps, you can tell to \fBgl_get_line()\fR to ignore that
1745 1745 signal by calling \fBgl_ignore_signal()\fR.
1746 1746 .sp
1747 1747 .LP
1748 1748 The \fIsigno\fR argument is the number of the signal (for example,
1749 1749 \fBSIGINT\fR) that you want to have ignored. If the specified signal is not
1750 1750 currently one of those being trapped, this function does nothing.
1751 1751 .sp
1752 1752 .LP
1753 1753 The \fBgl_trap_signal()\fR function allows you to either add a new signal to
1754 1754 the list that \fBgl_get_line()\fR traps or modify how it responds to a signal
1755 1755 that it already traps.
1756 1756 .sp
1757 1757 .LP
1758 1758 The \fIsigno\fR argument is the number of the signal that you want to have
1759 1759 trapped. The \fIflags\fR argument is a set of flags that determine the
1760 1760 environment in which the application's signal handler is invoked. The
1761 1761 \fIafter\fR argument tells \fBgl_get_line()\fR what to do after the
1762 1762 application's signal handler returns. The \fIerrno_value\fR tells
1763 1763 \fBgl_get_line()\fR what to set \fBerrno\fR to if told to abort.
1764 1764 .sp
1765 1765 .LP
1766 1766 The \fIflags\fR argument is a bitwise OR of zero or more of the following
1767 1767 enumerators:
1768 1768 .sp
1769 1769 .ne 2
1770 1770 .na
1771 1771 \fB\fBGLS_RESTORE_SIG\fR\fR
1772 1772 .ad
1773 1773 .RS 20n
1774 1774 Restore the caller's signal environment while handling the signal.
1775 1775 .RE
1776 1776
1777 1777 .sp
1778 1778 .ne 2
1779 1779 .na
1780 1780 \fB\fBGLS_RESTORE_TTY\fR\fR
1781 1781 .ad
1782 1782 .RS 20n
1783 1783 Restore the caller's terminal settings while handling the signal.
1784 1784 .RE
1785 1785
1786 1786 .sp
1787 1787 .ne 2
1788 1788 .na
1789 1789 \fB\fBGLS_RESTORE_LINE\fR\fR
1790 1790 .ad
1791 1791 .RS 20n
1792 1792 Move the cursor to the start of the line following the input line before
1793 1793 invoking the application's signal handler.
1794 1794 .RE
1795 1795
1796 1796 .sp
1797 1797 .ne 2
1798 1798 .na
1799 1799 \fB\fBGLS_REDRAW_LINE\fR\fR
1800 1800 .ad
1801 1801 .RS 20n
1802 1802 Redraw the input line when the application's signal handler returns.
1803 1803 .RE
1804 1804
1805 1805 .sp
1806 1806 .ne 2
1807 1807 .na
1808 1808 \fB\fBGLS_UNBLOCK_SIG\fR\fR
1809 1809 .ad
1810 1810 .RS 20n
1811 1811 Normally, if the calling program has a signal blocked (see
1812 1812 \fBsigprocmask\fR(2)), \fBgl_get_line()\fR does not trap that signal. This flag
1813 1813 tells \fBgl_get_line()\fR to trap the signal and unblock it for the duration of
1814 1814 the call to \fBgl_get_line()\fR.
1815 1815 .RE
1816 1816
1817 1817 .sp
1818 1818 .ne 2
1819 1819 .na
1820 1820 \fB\fBGLS_DONT_FORWARD\fR\fR
1821 1821 .ad
1822 1822 .RS 20n
1823 1823 If this flag is included, the signal will not be forwarded to the signal
1824 1824 handler of the calling program.
1825 1825 .RE
1826 1826
1827 1827 .sp
1828 1828 .LP
1829 1829 Two commonly useful flag combinations are also enumerated as follows:
1830 1830 .sp
1831 1831 .ne 2
1832 1832 .na
1833 1833 \fB\fBGLS_RESTORE_ENV\fR\fR
1834 1834 .ad
1835 1835 .RS 21n
1836 1836 \fBGLS_RESTORE_SIG\fR | \fBGLS_RESTORE_TTY\fR |\fBGLS_REDRAW_LINE\fR
1837 1837 .RE
1838 1838
1839 1839 .sp
1840 1840 .ne 2
1841 1841 .na
1842 1842 \fB\fBGLS_SUSPEND_INPUT\fR\fR
1843 1843 .ad
1844 1844 .RS 21n
1845 1845 \fBGLS_RESTORE_ENV\fR | \fBGLS_RESTORE_LINE\fR
1846 1846 .RE
1847 1847
1848 1848 .sp
1849 1849 .LP
1850 1850 If your signal handler, or the default system signal handler for this signal,
1851 1851 if you have not overridden it, never either writes to the terminal, nor
1852 1852 suspends or terminates the calling program, then you can safely set the
1853 1853 \fIflags\fR argument to 0.
1854 1854 .RS +4
1855 1855 .TP
1856 1856 .ie t \(bu
1857 1857 .el o
1858 1858 The cursor does not get left in the middle of the input line.
1859 1859 .RE
1860 1860 .RS +4
1861 1861 .TP
1862 1862 .ie t \(bu
1863 1863 .el o
1864 1864 So that the user can type in input and have it echoed.
1865 1865 .RE
1866 1866 .RS +4
1867 1867 .TP
1868 1868 .ie t \(bu
1869 1869 .el o
1870 1870 So that you do not need to end each output line with \er\en, instead of just
1871 1871 \en.
1872 1872 .RE
1873 1873 .sp
1874 1874 .LP
1875 1875 The \fBGL_RESTORE_ENV\fR combination is the same as \fBGL_SUSPEND_INPUT\fR,
1876 1876 except that it does not move the cursor. If your signal handler does not read
1877 1877 or write anything to the terminal, the user will not see any visible indication
1878 1878 that a signal was caught. This can be useful if you have a signal handler that
1879 1879 only occasionally writes to the terminal, where using \fBGL_SUSPEND_LINE\fR
1880 1880 would cause the input line to be unnecessarily duplicated when nothing had been
1881 1881 written to the terminal. Such a signal handler, when it does write to the
1882 1882 terminal, should be sure to start a new line at the start of its first write,
1883 1883 by writing a new line before returning. If the signal arrives while the user is
1884 1884 entering a line that only occupies a signal terminal line, or if the cursor is
1885 1885 on the last terminal line of a longer input line, this will have the same
1886 1886 effect as \fBGL_SUSPEND_INPUT\fR. Otherwise it will start writing on a line
1887 1887 that already contains part of the displayed input line. This does not do any
1888 1888 harm, but it looks a bit ugly, which is why the \fBGL_SUSPEND_INPUT\fR
1889 1889 combination is better if you know that you are always going to be writting to
1890 1890 the terminal.
1891 1891 .sp
1892 1892 .LP
1893 1893 The \fIafter\fR argument, which determines what \fBgl_get_line()\fR does after
1894 1894 the application's signal handler returns (if it returns), can take any one of
1895 1895 the following values:
1896 1896 .sp
1897 1897 .ne 2
1898 1898 .na
1899 1899 \fB\fBGLS_RETURN\fR\fR
1900 1900 .ad
1901 1901 .RS 16n
1902 1902 Return the completed input line, just as though the user had pressed the return
1903 1903 key.
1904 1904 .RE
1905 1905
1906 1906 .sp
1907 1907 .ne 2
1908 1908 .na
1909 1909 \fB\fBGLS_ABORT\fR\fR
1910 1910 .ad
1911 1911 .RS 16n
1912 1912 Cause \fBgl_get_line()\fR to abort. When this happens, \fBgl_get_line()\fR
1913 1913 returns \fINULL\fR, and a following call to \fBgl_return_status()\fR will
1914 1914 return \fBGLR_SIGNAL\fR. Note that if the application needs \fBerrno\fR always
1915 1915 to have a meaningful value when \fBgl_get_line()\fR returns \fINULL\fR, the
1916 1916 callback function should set \fBerrno\fR appropriately.
1917 1917 .RE
1918 1918
1919 1919 .sp
1920 1920 .ne 2
1921 1921 .na
1922 1922 \fB\fBGLS_CONTINUE\fR\fR
1923 1923 .ad
1924 1924 .RS 16n
1925 1925 Resume command line editing.
1926 1926 .RE
1927 1927
1928 1928 .sp
1929 1929 .LP
1930 1930 The \fIerrno_value\fR argument is intended to be combined with the
1931 1931 \fBGLS_ABORT\fR option, telling \fBgl_get_line()\fR what to set the standard
1932 1932 \fBerrno\fR variable to before returning \fINULL\fR to the calling program. It
1933 1933 can also, however, be used with the \fBGL_RETURN\fR option, in case you want to
1934 1934 have a way to distinguish between an input line that was entered using the
1935 1935 return key, and one that was entered by the receipt of a signal.
1936 1936 .SS "Reliable Signal Handling"
1937 1937 .sp
1938 1938 .LP
1939 1939 Signal handling is suprisingly hard to do reliably without race conditions. In
1940 1940 \fBgl_get_line()\fR a lot of care has been taken to allow applications to
1941 1941 perform reliable signal handling around \fBgl_get_line()\fR. This section
1942 1942 explains how to make use of this.
1943 1943 .sp
1944 1944 .LP
1945 1945 As an example of the problems that can arise if the application is not written
1946 1946 correctly, imagine that one's application has a \fBSIGINT\fR signal handler
1947 1947 that sets a global flag. Now suppose that the application tests this flag just
1948 1948 before invoking \fBgl_get_line()\fR. If a \fBSIGINT\fR signal happens to be
1949 1949 received in the small window of time between the statement that tests the value
1950 1950 of this flag, and the statement that calls \fBgl_get_line()\fR, then
1951 1951 \fBgl_get_line()\fR will not see the signal, and will not be interrupted. As a
1952 1952 result, the application will not be able to respond to the signal until the
1953 1953 user gets around to finishing entering the input line and \fBgl_get_line()\fR
1954 1954 returns. Depending on the application, this might or might not be a disaster,
1955 1955 but at the very least it would puzzle the user.
1956 1956 .sp
1957 1957 .LP
1958 1958 The way to avoid such problems is to do the following.
1959 1959 .RS +4
1960 1960 .TP
1961 1961 1.
1962 1962 If needed, use the \fBgl_trap_signal()\fR function to configure
1963 1963 \fBgl_get_line()\fR to abort when important signals are caught.
1964 1964 .RE
1965 1965 .RS +4
1966 1966 .TP
1967 1967 2.
1968 1968 Configure \fBgl_get_line()\fR such that if any of the signals that it
1969 1969 catches are blocked when \fBgl_get_line()\fR is called, they will be unblocked
1970 1970 automatically during times when \fBgl_get_line()\fR is waiting for I/O. This
1971 1971 can be done either on a per signal basis, by calling the \fBgl_trap_signal()\fR
1972 1972 function, and specifying the \fBGLS_UNBLOCK\fR attribute of the signal, or
1973 1973 globally by calling the \fBgl_catch_blocked()\fR function. This function simply
1974 1974 adds the \fBGLS_UNBLOCK\fR attribute to all of the signals that it is currently
1975 1975 configured to trap.
1976 1976 .RE
1977 1977 .RS +4
1978 1978 .TP
1979 1979 3.
1980 1980 Just before calling \fBgl_get_line()\fR, block delivery of all of the
1981 1981 signals that \fBgl_get_line()\fR is configured to trap. This can be done using
1982 1982 the POSIX sigprocmask function in conjunction with the \fBgl_list_signals()\fR
1983 1983 function. This function returns the set of signals that it is currently
1984 1984 configured to catch in the set argument, which is in the form required by
1985 1985 \fBsigprocmask\fR(2).
1986 1986 .RE
1987 1987 .RS +4
1988 1988 .TP
1989 1989 4.
1990 1990 In the example, one would now test the global flag that the signal handler
1991 1991 sets, knowing that there is now no danger of this flag being set again until
1992 1992 \fBgl_get_line()\fR unblocks its signals while performing I/O.
1993 1993 .RE
1994 1994 .RS +4
1995 1995 .TP
1996 1996 5.
1997 1997 Eventually \fBgl_get_line()\fR returns, either because a signal was caught,
1998 1998 an error occurred, or the user finished entering their input line.
1999 1999 .RE
2000 2000 .RS +4
2001 2001 .TP
2002 2002 6.
2003 2003 Now one would check the global signal flag again, and if it is set, respond
2004 2004 to it, and zero the flag.
2005 2005 .RE
2006 2006 .RS +4
2007 2007 .TP
2008 2008 7.
2009 2009 Use \fBsigprocmask()\fR to unblock the signals that were blocked in step 3.
2010 2010 .RE
2011 2011 .sp
2012 2012 .LP
2013 2013 The same technique can be used around certain POSIX signal-aware functions,
2014 2014 such as \fBsigsetjmp\fR(3C) and \fBsigsuspend\fR(2), and in particular, the
2015 2015 former of these two functions can be used in conjunction with
2016 2016 \fBsiglongjmp\fR(3C) to implement race-condition free signal handling around
2017 2017 other long-running system calls. The \fBgl_get_line()\fR function manages to
2018 2018 reliably trap signals around calls to functions like \fBread\fR(2) and
2019 2019 \fBselect\fR(3C) without race conditions.
2020 2020 .sp
2021 2021 .LP
2022 2022 The \fBgl_get_line()\fR function first uses the POSIX \fBsigprocmask()\fR
2023 2023 function to block the delivery of all of the signals that it is currently
2024 2024 configured to catch. This is redundant if the application has already blocked
2025 2025 them, but it does no harm. It undoes this step just before returning.
2026 2026 .sp
2027 2027 .LP
2028 2028 Whenever \fBgl_get_line()\fR needs to call read or select to wait for input
2029 2029 from the user, it first calls the POSIX \fBsigsetjmp()\fR function, being sure
2030 2030 to specify a non-zero value for its \fIsavemask\fR argument.
2031 2031 .sp
2032 2032 .LP
2033 2033 If \fBsigsetjmp()\fR returns zero, \fBgl_get_line()\fR then does the following.
2034 2034 .RS +4
2035 2035 .TP
2036 2036 1.
2037 2037 It uses the POSIX \fBsigaction\fR(2) function to register a temporary signal
2038 2038 handler to all of the signals that it is configured to catch. This signal
2039 2039 handler does two things.
2040 2040 .RS +4
2041 2041 .TP
2042 2042 a.
2043 2043 It records the number of the signal that was received in a file-scope
2044 2044 variable.
2045 2045 .RE
2046 2046 .RS +4
2047 2047 .TP
2048 2048 b.
2049 2049 It then calls the POSIX \fBsiglongjmp()\fR function using the buffer that
2050 2050 was passed to \fBsigsetjmp()\fR for its first argument and a non-zero value for
2051 2051 its second argument.
2052 2052 .RE
2053 2053 When this signal handler is registered, the \fIsa_mask\fR member of the
2054 2054 \fBstruct sigaction\fR \fIact\fR argument of the call to \fBsigaction()\fR is
2055 2055 configured to contain all of the signals that \fBgl_get_line()\fR is catching.
2056 2056 This ensures that only one signal will be caught at once by our signal handler,
2057 2057 which in turn ensures that multiple instances of our signal handler do not
2058 2058 tread on each other's toes.
2059 2059 .RE
2060 2060 .RS +4
2061 2061 .TP
2062 2062 2.
2063 2063 Now that the signal handler has been set up, \fBgl_get_line()\fR unblocks
2064 2064 all of the signals that it is configured to catch.
2065 2065 .RE
2066 2066 .RS +4
2067 2067 .TP
2068 2068 3.
2069 2069 It then calls the \fBread()\fR or \fBselect()\fR function to wait for
2070 2070 keyboard input.
2071 2071 .RE
2072 2072 .RS +4
2073 2073 .TP
2074 2074 4.
2075 2075 If this function returns (that is, no signal is received),
2076 2076 \fBgl_get_line()\fR blocks delivery of the signals of interest again.
2077 2077 .RE
2078 2078 .RS +4
2079 2079 .TP
2080 2080 5.
2081 2081 It then reinstates the signal handlers that were displaced by the one that
2082 2082 was just installed.
2083 2083 .RE
2084 2084 .sp
2085 2085 .LP
2086 2086 Alternatively, if \fBsigsetjmp()\fR returns non-zero, this means that one of
2087 2087 the signals being trapped was caught while the above steps were executing. When
2088 2088 this happens, \fBgl_get_line()\fR does the following.
2089 2089 .sp
2090 2090 .LP
2091 2091 First, note that when a call to \fBsiglongjmp()\fR causes \fBsigsetjmp()\fR to
2092 2092 return, provided that the \fIsavemask\fR argument of \fBsigsetjmp()\fR was
2093 2093 non-zero, the signal process mask is restored to how it was when
2094 2094 \fBsigsetjmp()\fR was called. This is the important difference between
2095 2095 \fBsigsetjmp()\fR and the older problematic \fBsetjmp\fR(3C), and is the
2096 2096 essential ingredient that makes it possible to avoid signal handling race
2097 2097 conditions. Because of this we are guaranteed that all of the signals that we
2098 2098 blocked before calling \fBsigsetjmp()\fR are blocked again as soon as any
2099 2099 signal is caught. The following statements, which are then executed, are thus
2100 2100 guaranteed to be executed without any further signals being caught.
2101 2101 .RS +4
2102 2102 .TP
2103 2103 1.
2104 2104 If so instructed by the \fBgl_get_line()\fR configuration attributes of the
2105 2105 signal that was caught, \fBgl_get_line()\fR restores the terminal attributes to
2106 2106 the state that they had when \fBgl_get_line()\fR was called. This is
2107 2107 particularly important for signals that suspend or terminate the process, since
2108 2108 otherwise the terminal would be left in an unusable state.
2109 2109 .RE
2110 2110 .RS +4
2111 2111 .TP
2112 2112 2.
2113 2113 It then reinstates the application's signal handlers.
2114 2114 .RE
2115 2115 .RS +4
2116 2116 .TP
2117 2117 3.
2118 2118 Then it uses the C standard-library \fBraise\fR(3C) function to re-send the
2119 2119 application the signal that was caught.
2120 2120 .RE
2121 2121 .RS +4
2122 2122 .TP
2123 2123 4.
2124 2124 Next it unblocks delivery of the signal that we just sent. This results in
2125 2125 the signal that was just sent by \fBraise()\fR being caught by the
2126 2126 application's original signal handler, which can now handle it as it sees fit.
2127 2127 .RE
2128 2128 .RS +4
2129 2129 .TP
2130 2130 5.
2131 2131 If the signal handler returns (that is, it does not terminate the process),
2132 2132 \fBgl_get_line()\fR blocks delivery of the above signal again.
2133 2133 .RE
2134 2134 .RS +4
2135 2135 .TP
2136 2136 6.
2137 2137 It then undoes any actions performed in the first of the above steps and
2138 2138 redisplays the line, if the signal configuration calls for this.
2139 2139 .RE
2140 2140 .RS +4
2141 2141 .TP
2142 2142 7.
2143 2143 \fBgl_get_line()\fR then either resumes trying to read a character, or
2144 2144 aborts, depending on the configuration of the signal that was caught.
2145 2145 .RE
2146 2146 .sp
2147 2147 .LP
2148 2148 What the above steps do in essence is to take asynchronously delivered signals
2149 2149 and handle them synchronously, one at a time, at a point in the code where
2150 2150 \fBgl_get_line()\fR has complete control over its environment.
2151 2151 .SS "The Terminal Size"
2152 2152 .sp
2153 2153 .LP
2154 2154 On most systems the combination of the \fBTIOCGWINSZ\fR ioctl and the
2155 2155 \fBSIGWINCH\fR signal is used to maintain an accurate idea of the terminal
2156 2156 size. The terminal size is newly queried every time that \fBgl_get_line()\fR is
2157 2157 called and whenever a \fBSIGWINCH\fR signal is received.
2158 2158 .sp
2159 2159 .LP
2160 2160 On the few systems where this mechanism is not available, at startup
2161 2161 \fBnew_GetLine()\fR first looks for the \fBLINES\fR and \fBCOLUMNS\fR
2162 2162 environment variables. If these are not found, or they contain unusable values,
2163 2163 then if a terminal information database like \fBterminfo\fR or \fBtermcap\fR is
2164 2164 available, the default size of the terminal is looked up in this database. If
2165 2165 this too fails to provide the terminal size, a default size of 80 columns by 24
2166 2166 lines is used.
2167 2167 .sp
2168 2168 .LP
2169 2169 Even on systems that do support ioctl(\fBTIOCGWINSZ\fR), if the terminal is on
2170 2170 the other end of a serial line, the terminal driver generally has no way of
2171 2171 detecting when a resize occurs or of querying what the current size is. In such
2172 2172 cases no \fBSIGWINCH\fR is sent to the process, and the dimensions returned by
2173 2173 ioctl(\fBTIOCGWINSZ\fR) are not correct. The only way to handle such instances
2174 2174 is to provide a way for the user to enter a command that tells the remote
2175 2175 system what the new size is. This command would then call the
2176 2176 \fBgl_set_term_size()\fR function to tell \fBgl_get_line()\fR about the change
2177 2177 in size.
2178 2178 .sp
2179 2179 .LP
2180 2180 The \fIncolumn\fR and \fInline\fR arguments are used to specify the new
2181 2181 dimensions of the terminal, and must not be less than 1. On systems that do
2182 2182 support ioctl(\fBTIOCGWINSZ\fR), this function first calls
2183 2183 ioctl(\fBTIOCSWINSZ\fR) to tell the terminal driver about the change in size.
2184 2184 In non-blocking server-I/O mode, if a line is currently being input, the input
2185 2185 line is then redrawn to accomodate the changed size. Finally the new values are
2186 2186 recorded in \fIgl\fR for future use by \fBgl_get_line()\fR.
2187 2187 .sp
2188 2188 .LP
2189 2189 The \fBgl_terminal_size()\fR function allows you to query the current size of
2190 2190 the terminal, and install an alternate fallback size for cases where the size
2191 2191 is not available. Beware that the terminal size will not be available if
2192 2192 reading from a pipe or a file, so the default values can be important even on
2193 2193 systems that do support ways of finding out the terminal size.
2194 2194 .sp
2195 2195 .LP
2196 2196 This function first updates \fBgl_get_line()\fR's fallback terminal dimensions,
2197 2197 then records its findings in the return value.
2198 2198 .sp
2199 2199 .LP
2200 2200 The \fIdef_ncolumn\fR and \fIdef_nline\fR arguments specify the default number
2201 2201 of terminal columns and lines to use if the terminal size cannot be determined
2202 2202 by ioctl(\fBTIOCGWINSZ\fR) or environment variables.
2203 2203 .SS "Hiding What You Type"
2204 2204 .sp
2205 2205 .LP
2206 2206 When entering sensitive information, such as passwords, it is best not to have
2207 2207 the text that you are entering echoed on the terminal. Furthermore, such text
2208 2208 should not be recorded in the history list, since somebody finding your
2209 2209 terminal unattended could then recall it, or somebody snooping through your
2210 2210 directories could see it in your history file. With this in mind, the
2211 2211 \fBgl_echo_mode()\fR function allows you to toggle on and off the display and
2212 2212 archival of any text that is subsequently entered in calls to
2213 2213 \fBgl_get_line()\fR.
2214 2214 .sp
2215 2215 .LP
2216 2216 The \fIenable\fR argument specifies whether entered text should be visible or
2217 2217 not. If it is 0, then subsequently entered lines will not be visible on the
2218 2218 terminal, and will not be recorded in the history list. If it is 1, then
2219 2219 subsequent input lines will be displayed as they are entered, and provided that
2220 2220 history has not been turned off with a call to \fBgl_toggle_history()\fR, then
2221 2221 they will also be archived in the history list. Finally, if the enable argument
2222 2222 is -1, then the echoing mode is left unchanged, which allows you to
2223 2223 non-destructively query the current setting through the return value. In all
2224 2224 cases, the return value of the function is 0 if echoing was disabled before the
2225 2225 function was called, and 1 if it was enabled.
2226 2226 .sp
2227 2227 .LP
2228 2228 When echoing is turned off, note that although tab completion will invisibly
2229 2229 complete your prefix as far as possible, ambiguous completions will not be
2230 2230 displayed.
2231 2231 .SS "Single Character Queries"
2232 2232 .sp
2233 2233 .LP
2234 2234 Using \fBgl_get_line()\fR to query the user for a single character reply, is
2235 2235 inconvenient for the user, since they must hit the enter or return key before
2236 2236 the character that they typed is returned to the program. Thus the
2237 2237 \fBgl_query_char()\fR function has been provided for single character queries
2238 2238 like this.
2239 2239 .sp
2240 2240 .LP
2241 2241 This function displays the specified prompt at the start of a new line, and
2242 2242 waits for the user to type a character. When the user types a character,
2243 2243 \fBgl_query_char()\fR displays it to the right of the prompt, starts a newline,
2244 2244 then returns the character to the calling program. The return value of the
2245 2245 function is the character that was typed. If the read had to be aborted for
2246 2246 some reason, EOF is returned instead. In the latter case, the application can
2247 2247 call the previously documented \fBgl_return_status()\fR, to find out what went
2248 2248 wrong. This could, for example, have been the reception of a signal, or the
2249 2249 optional inactivity timer going off.
2250 2250 .sp
2251 2251 .LP
2252 2252 If the user simply hits enter, the value of the \fIdefchar\fR argument is
2253 2253 substituted. This means that when the user hits either newline or return, the
2254 2254 character specified in \fIdefchar\fR, is displayed after the prompt, as though
2255 2255 the user had typed it, as well as being returned to the calling application. If
2256 2256 such a replacement is not important, simply pass '\en' as the value of
2257 2257 \fIdefchar\fR.
2258 2258 .sp
2259 2259 .LP
2260 2260 If the entered character is an unprintable character, it is displayed
2261 2261 symbolically. For example, control-A is displayed as \fB^A\fR, and characters
2262 2262 beyond 127 are displayed in octal, preceded by a backslash.
2263 2263 .sp
2264 2264 .LP
2265 2265 As with \fBgl_get_line()\fR, echoing of the entered character can be disabled
2266 2266 using the \fBgl_echo_mode()\fR function.
2267 2267 .sp
2268 2268 .LP
2269 2269 If the calling process is suspended while waiting for the user to type their
2270 2270 response, the cursor is moved to the line following the prompt line, then when
2271 2271 the process resumes, the prompt is redisplayed, and \fBgl_query_char()\fR
2272 2272 resumes waiting for the user to type a character.
2273 2273 .sp
2274 2274 .LP
2275 2275 Note that in non-blocking server mode, if an incomplete input line is in the
2276 2276 process of being read when \fBgl_query_char()\fR is called, the partial input
2277 2277 line is discarded, and erased from the terminal, before the new prompt is
2278 2278 displayed. The next call to \fBgl_get_line()\fR will thus start editing a new
2279 2279 line.
2280 2280 .SS "Reading Raw Characters"
2281 2281 .sp
2282 2282 .LP
2283 2283 Whereas the \fBgl_query_char()\fR function visibly prompts the user for a
2284 2284 character, and displays what they typed, the \fBgl_read_char()\fR function
2285 2285 reads a signal character from the user, without writing anything to the
2286 2286 terminal, or perturbing any incompletely entered input line. This means that it
2287 2287 can be called not only from between calls to \fBgl_get_line()\fR, but also from
2288 2288 callback functions that the application has registered to be called by
2289 2289 \fBgl_get_line()\fR.
2290 2290 .sp
2291 2291 .LP
2292 2292 On success, the return value of \fBgl_read_char()\fR is the character that was
2293 2293 read. On failure, EOF is returned, and the \fBgl_return_status()\fR function
2294 2294 can be called to find out what went wrong. Possibilities include the optional
2295 2295 inactivity timer going off, the receipt of a signal that is configured to abort
2296 2296 \fBgl_get_line()\fR, or terminal I/O blocking, when in non-blocking server-I/O
2297 2297 mode.
2298 2298 .sp
2299 2299 .LP
2300 2300 Beware that certain keyboard keys, such as function keys, and cursor keys,
2301 2301 usually generate at least three characters each, so a single call to
2302 2302 \fBgl_read_char()\fR will not be enough to identify such keystrokes.
2303 2303 .SS "Clearing The Terminal"
2304 2304 .sp
2305 2305 .LP
2306 2306 The calling program can clear the terminal by calling
2307 2307 \fBgl_erase_terminal()\fR. In non-blocking server-I/O mode, this function also
2308 2308 arranges for the current input line to be redrawn from scratch when
2309 2309 \fBgl_get_line()\fR is next called.
2310 2310 .SS "Displaying Text Dynamically"
2311 2311 .sp
2312 2312 .LP
2313 2313 Between calls to \fBgl_get_line()\fR, the \fBgl_display_text()\fR function
2314 2314 provides a convenient way to display paragraphs of text, left-justified and
2315 2315 split over one or more terminal lines according to the constraints of the
2316 2316 current width of the terminal. Examples of the use of this function may be
2317 2317 found in the demo programs, where it is used to display introductions. In those
2318 2318 examples the advanced use of optional prefixes, suffixes and filled lines to
2319 2319 draw a box around the text is also illustrated.
2320 2320 .sp
2321 2321 .LP
2322 2322 If \fIgl\fR is not currently connected to a terminal, for example if the output
2323 2323 of a program that uses \fBgl_get_line()\fR is being piped to another program or
2324 2324 redirected to a file, then the value of the \fIdef_width\fR parameter is used
2325 2325 as the terminal width.
2326 2326 .sp
2327 2327 .LP
2328 2328 The \fIindentation\fR argument specifies the number of characters to use to
2329 2329 indent each line of ouput. The \fIfill_char\fR argument specifies the character
2330 2330 that will be used to perform this indentation.
2331 2331 .sp
2332 2332 .LP
2333 2333 The \fIprefix\fR argument can be either \fINULL\fR or a string to place at the
2334 2334 beginning of each new line (after any indentation). Similarly, the \fIsuffix\fR
2335 2335 argument can be either \fINULL\fR or a string to place at the end of each line.
2336 2336 The suffix is placed flush against the right edge of the terminal, and any
2337 2337 space between its first character and the last word on that line is filled with
2338 2338 the character specified by the \fIfill_char\fR argument. Normally the
2339 2339 fill-character is a space.
2340 2340 .sp
2341 2341 .LP
2342 2342 The \fIstart\fR argument tells \fBgl_display_text()\fR how many characters have
2343 2343 already been written to the current terminal line, and thus tells it the
2344 2344 starting column index of the cursor. Since the return value of
2345 2345 \fBgl_display_text()\fR is the ending column index of the cursor, by passing
2346 2346 the return value of one call to the start argument of the next call, a
2347 2347 paragraph that is broken between more than one string can be composed by
2348 2348 calling \fBgl_display_text()\fR for each successive portion of the paragraph.
2349 2349 Note that literal newline characters are necessary at the end of each paragraph
2350 2350 to force a new line to be started.
2351 2351 .sp
2352 2352 .LP
2353 2353 On error, \fBgl_display_text()\fR returns -1.
2354 2354 .SS "Callback Function Facilities"
2355 2355 .sp
2356 2356 .LP
2357 2357 Unless otherwise stated, callback functions such as tab completion callbacks
2358 2358 and event callbacks should not call any functions in this module. The following
2359 2359 functions, however, are designed specifically to be used by callback functions.
2360 2360 .sp
2361 2361 .LP
2362 2362 Calling the \fBgl_replace_prompt()\fR function from a callback tells
2363 2363 \fBgl_get_line()\fR to display a different prompt when the callback returns.
2364 2364 Except in non-blocking server mode, it has no effect if used between calls to
2365 2365 \fBgl_get_line()\fR. In non-blocking server mode, when used between two calls
2366 2366 to \fBgl_get_line()\fR that are operating on the same input line, the current
2367 2367 input line will be re-drawn with the new prompt on the following call to
2368 2368 \fBgl_get_line()\fR.
2369 2369 .SS "International Character Sets"
2370 2370 .sp
2371 2371 .LP
2372 2372 Since \fBlibtecla\fR(3LIB) version 1.4.0, \fBgl_get_line()\fR has been 8-bit
2373 2373 clean. This means that all 8-bit characters that are printable in the user's
2374 2374 current locale are now displayed verbatim and included in the returned input
2375 2375 line. Assuming that the calling program correctly contains a call like the
2376 2376 following,
2377 2377 .sp
2378 2378 .in +2
2379 2379 .nf
2380 2380 setlocale(LC_CTYPE, "")
2381 2381 .fi
2382 2382 .in -2
2383 2383
2384 2384 .sp
2385 2385 .LP
2386 2386 then the current locale is determined by the first of the environment variables
2387 2387 \fBLC_CTYPE\fR, \fBLC_ALL\fR, and \fBLANG\fR that is found to contain a valid
2388 2388 locale name. If none of these variables are defined, or the program neglects to
2389 2389 call \fBsetlocale\fR(3C), then the default C locale is used, which is US 7-bit
2390 2390 ASCII. On most UNIX-like platforms, you can get a list of valid locales by
2391 2391 typing the command:
2392 2392 .sp
2393 2393 .in +2
2394 2394 .nf
2395 2395 locale -a
2396 2396 .fi
2397 2397 .in -2
2398 2398 .sp
2399 2399
2400 2400 .sp
2401 2401 .LP
2402 2402 at the shell prompt. Further documentation on how the user can make use of this
2403 2403 to enter international characters can be found in the \fBtecla\fR(5) man page.
2404 2404 .SS "Thread Safety"
2405 2405 .sp
2406 2406 .LP
2407 2407 Unfortunately neither \fBterminfo\fR nor \fBtermcap\fR were designed to be
2408 2408 reentrant, so you cannot safely use the functions of the getline module in
2409 2409 multiple threads (you can use the separate file-expansion and word-completion
2410 2410 modules in multiple threads, see the corresponding man pages for details).
2411 2411 However due to the use of POSIX reentrant functions for looking up home
2412 2412 directories, it is safe to use this module from a single thread of a
2413 2413 multi-threaded program, provided that your other threads do not use any
2414 2414 \fBtermcap\fR or \fBterminfo\fR functions.
2415 2415 .SH ATTRIBUTES
2416 2416 .sp
2417 2417 .LP
2418 2418 See \fBattributes\fR(5) for descriptions of the following attributes:
2419 2419 .sp
2420 2420
2421 2421 .sp
2422 2422 .TS
2423 2423 box;
2424 2424 c | c
2425 2425 l | l .
2426 2426 ATTRIBUTE TYPE ATTRIBUTE VALUE
2427 2427 _
2428 2428 Interface Stability Committed
2429 2429 _
2430 2430 MT-Level MT-Safe
2431 2431 .TE
2432 2432
2433 2433 .SH SEE ALSO
2434 2434 .sp
2435 2435 .LP
2436 2436 \fBcpl_complete_word\fR(3TECLA), \fBef_expand_file\fR(3TECLA),
2437 2437 \fBgl_io_mode\fR(3TECLA), \fBlibtecla\fR(3LIB), \fBpca_lookup_file\fR(3TECLA),
2438 2438 \fBattributes\fR(5), \fBtecla\fR(5)
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