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