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