xref: /openbsd-src/lib/libcurses/tinfo/comp_scan.c (revision 1fe33145a0a9b1310a0413297a8deb871918b27f)
1 /****************************************************************************
2  * Copyright (c) 1998,1999,2000 Free Software Foundation, Inc.              *
3  *                                                                          *
4  * Permission is hereby granted, free of charge, to any person obtaining a  *
5  * copy of this software and associated documentation files (the            *
6  * "Software"), to deal in the Software without restriction, including      *
7  * without limitation the rights to use, copy, modify, merge, publish,      *
8  * distribute, distribute with modifications, sublicense, and/or sell       *
9  * copies of the Software, and to permit persons to whom the Software is    *
10  * furnished to do so, subject to the following conditions:                 *
11  *                                                                          *
12  * The above copyright notice and this permission notice shall be included  *
13  * in all copies or substantial portions of the Software.                   *
14  *                                                                          *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
16  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
18  * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
19  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
20  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
21  * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
22  *                                                                          *
23  * Except as contained in this notice, the name(s) of the above copyright   *
24  * holders shall not be used in advertising or otherwise to promote the     *
25  * sale, use or other dealings in this Software without prior written       *
26  * authorization.                                                           *
27  ****************************************************************************/
28 
29 /****************************************************************************
30  *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
31  *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
32  ****************************************************************************/
33 
34 /*
35  *	comp_scan.c --- Lexical scanner for terminfo compiler.
36  *
37  *	_nc_reset_input()
38  *	_nc_get_token()
39  *	_nc_panic_mode()
40  *	int _nc_syntax;
41  *	int _nc_curr_line;
42  *	long _nc_curr_file_pos;
43  *	long _nc_comment_start;
44  *	long _nc_comment_end;
45  */
46 
47 #include <curses.priv.h>
48 
49 #include <ctype.h>
50 #include <term_entry.h>
51 #include <tic.h>
52 
53 MODULE_ID("$From: comp_scan.c,v 1.44 2000/06/10 21:59:21 tom Exp $")
54 
55 /*
56  * Maximum length of string capability we'll accept before raising an error.
57  * Yes, there is a real capability in /etc/termcap this long, an "is".
58  */
59 #define MAXCAPLEN	600
60 
61 #define iswhite(ch)	(ch == ' '  ||  ch == '\t')
62 
63 int _nc_syntax = 0;		/* termcap or terminfo? */
64 long _nc_curr_file_pos = 0;	/* file offset of current line */
65 long _nc_comment_start = 0;	/* start of comment range before name */
66 long _nc_comment_end = 0;	/* end of comment range before name */
67 long _nc_start_line = 0;	/* start line of current entry */
68 
69 struct token _nc_curr_token =
70 {0, 0, 0};
71 
72 /*****************************************************************************
73  *
74  * Token-grabbing machinery
75  *
76  *****************************************************************************/
77 
78 static bool first_column;	/* See 'next_char()' below */
79 static char separator;		/* capability separator */
80 static int pushtype;		/* type of pushback token */
81 static char pushname[MAX_NAME_SIZE + 1];
82 
83 static int last_char(void);
84 static int next_char(void);
85 static long stream_pos(void);
86 static bool end_of_stream(void);
87 static void push_back(char c);
88 
89 /* Assume we may be looking at a termcap-style continuation */
90 static inline int
91 eat_escaped_newline(int ch)
92 {
93     if (ch == '\\')
94 	while ((ch = next_char()) == '\n' || iswhite(ch))
95 	    continue;
96     return ch;
97 }
98 
99 /*
100  *	int
101  *	get_token()
102  *
103  *	Scans the input for the next token, storing the specifics in the
104  *	global structure 'curr_token' and returning one of the following:
105  *
106  *		NAMES		A line beginning in column 1.  'name'
107  *				will be set to point to everything up to but
108  *				not including the first separator on the line.
109  *		BOOLEAN		An entry consisting of a name followed by
110  *				a separator.  'name' will be set to point to
111  *				the name of the capability.
112  *		NUMBER		An entry of the form
113  *					name#digits,
114  *				'name' will be set to point to the capability
115  *				name and 'valnumber' to the number given.
116  *		STRING		An entry of the form
117  *					name=characters,
118  *				'name' is set to the capability name and
119  *				'valstring' to the string of characters, with
120  *				input translations done.
121  *		CANCEL		An entry of the form
122  *					name@,
123  *				'name' is set to the capability name and
124  *				'valnumber' to -1.
125  *		EOF		The end of the file has been reached.
126  *
127  *	A `separator' is either a comma or a semicolon, depending on whether
128  *	we are in termcap or terminfo mode.
129  *
130  */
131 
132 int
133 _nc_get_token(void)
134 {
135     static const char terminfo_punct[] = "@%&*!#";
136     long number;
137     int type;
138     int ch;
139     char *numchk;
140     char numbuf[80];
141     unsigned found;
142     static char buffer[MAX_ENTRY_SIZE];
143     char *ptr;
144     int dot_flag = FALSE;
145     long token_start;
146 
147     if (pushtype != NO_PUSHBACK) {
148 	int retval = pushtype;
149 
150 	_nc_set_type(pushname);
151 	DEBUG(3, ("pushed-back token: `%s', class %d",
152 		_nc_curr_token.tk_name, pushtype));
153 
154 	pushtype = NO_PUSHBACK;
155 	pushname[0] = '\0';
156 
157 	/* currtok wasn't altered by _nc_push_token() */
158 	return (retval);
159     }
160 
161     if (end_of_stream())
162 	return (EOF);
163 
164   start_token:
165     token_start = stream_pos();
166     while ((ch = next_char()) == '\n' || iswhite(ch))
167 	continue;
168 
169     ch = eat_escaped_newline(ch);
170 
171     if (ch == EOF)
172 	type = EOF;
173     else {
174 	/* if this is a termcap entry, skip a leading separator */
175 	if (separator == ':' && ch == ':')
176 	    ch = next_char();
177 
178 	if (ch == '.'
179 #ifdef NCURSES_EXT_FUNCS
180 	 && !_nc_disable_period
181 #endif
182 	) {
183 	    dot_flag = TRUE;
184 	    DEBUG(8, ("dot-flag set"));
185 
186 	    while ((ch = next_char()) == '.' || iswhite(ch))
187 		continue;
188 	}
189 
190 	if (ch == EOF) {
191 	    type = EOF;
192 	    goto end_of_token;
193 	}
194 
195 	/* have to make some punctuation chars legal for terminfo */
196 	if (!isalnum(ch)
197 #ifdef NCURSES_EXT_FUNCS
198 	 && !(ch == '.' && _nc_disable_period)
199 #endif
200 	 && !strchr(terminfo_punct, (char) ch)) {
201 	    _nc_warning("Illegal character (expected alphanumeric or %s) - %s",
202 		terminfo_punct, unctrl(ch));
203 	    _nc_panic_mode(separator);
204 	    goto start_token;
205 	}
206 
207 	ptr = buffer;
208 	*(ptr++) = ch;
209 
210 	if (first_column) {
211 	    char *desc;
212 
213 	    _nc_comment_start = token_start;
214 	    _nc_comment_end = _nc_curr_file_pos;
215 	    _nc_start_line = _nc_curr_line;
216 
217 	    _nc_syntax = ERR;
218 	    while ((ch = next_char()) != '\n') {
219 		if (ch == EOF)
220 		    _nc_err_abort("premature EOF");
221 		else if (ch == ':' && last_char() != ',') {
222 		    _nc_syntax = SYN_TERMCAP;
223 		    separator = ':';
224 		    break;
225 		} else if (ch == ',') {
226 		    _nc_syntax = SYN_TERMINFO;
227 		    separator = ',';
228 		    /*
229 		     * Fall-through here is not an accident.
230 		     * The idea is that if we see a comma, we
231 		     * figure this is terminfo unless we
232 		     * subsequently run into a colon -- but
233 		     * we don't stop looking for that colon until
234 		     * hitting a newline.  This allows commas to
235 		     * be embedded in description fields of
236 		     * either syntax.
237 		     */
238 		    /* FALLTHRU */
239 		} else
240 		    ch = eat_escaped_newline(ch);
241 
242 		*ptr++ = ch;
243 	    }
244 	    ptr[0] = '\0';
245 	    if (_nc_syntax == ERR) {
246 		/*
247 		 * Grrr...what we ought to do here is barf,
248 		 * complaining that the entry is malformed.
249 		 * But because a couple of name fields in the
250 		 * 8.2 termcap file end with |\, we just have
251 		 * to assume it's termcap syntax.
252 		 */
253 		_nc_syntax = SYN_TERMCAP;
254 		separator = ':';
255 	    } else if (_nc_syntax == SYN_TERMINFO) {
256 		/* throw away trailing /, *$/ */
257 		for (--ptr; iswhite(*ptr) || *ptr == ','; ptr--)
258 		    continue;
259 		ptr[1] = '\0';
260 	    }
261 
262 	    /*
263 	     * This is the soonest we have the terminal name
264 	     * fetched.  Set up for following warning messages.
265 	     */
266 	    ptr = strchr(buffer, '|');
267 	    if (ptr == (char *) NULL)
268 		ptr = buffer + strlen(buffer);
269 	    ch = *ptr;
270 	    *ptr = '\0';
271 	    _nc_set_type(buffer);
272 	    *ptr = ch;
273 
274 	    /*
275 	     * Compute the boundary between the aliases and the
276 	     * description field for syntax-checking purposes.
277 	     */
278 	    desc = strrchr(buffer, '|');
279 	    if (desc) {
280 		if (*desc == '\0')
281 		    _nc_warning("empty longname field");
282 		else if (strchr(desc, ' ') == (char *) NULL)
283 		    _nc_warning("older tic versions may treat the description field as an alias");
284 	    }
285 	    if (!desc)
286 		desc = buffer + strlen(buffer);
287 
288 	    /*
289 	     * Whitespace in a name field other than the long name
290 	     * can confuse rdist and some termcap tools.  Slashes
291 	     * are a no-no.  Other special characters can be
292 	     * dangerous due to shell expansion.
293 	     */
294 	    for (ptr = buffer; ptr < desc; ptr++) {
295 		if (isspace(*ptr)) {
296 		    _nc_warning("whitespace in name or alias field");
297 		    break;
298 		} else if (*ptr == '/') {
299 		    _nc_warning("slashes aren't allowed in names or aliases");
300 		    break;
301 		} else if (strchr("$[]!*?", *ptr)) {
302 		    _nc_warning("dubious character `%c' in name or alias field", *ptr);
303 		    break;
304 		}
305 	    }
306 
307 	    ptr = buffer;
308 
309 	    _nc_curr_token.tk_name = buffer;
310 	    type = NAMES;
311 	} else {
312 	    while ((ch = next_char()) != EOF) {
313 		if (!isalnum(ch)) {
314 		    if (_nc_syntax == SYN_TERMINFO) {
315 			if (ch != '_')
316 			    break;
317 		    } else {	/* allow ';' for "k;" */
318 			if (ch != ';')
319 			    break;
320 		    }
321 		}
322 		*(ptr++) = ch;
323 	    }
324 
325 	    *ptr++ = '\0';
326 	    switch (ch) {
327 	    case ',':
328 	    case ':':
329 		if (ch != separator)
330 		    _nc_err_abort("Separator inconsistent with syntax");
331 		_nc_curr_token.tk_name = buffer;
332 		type = BOOLEAN;
333 		break;
334 	    case '@':
335 		if ((ch = next_char()) != separator)
336 		    _nc_warning("Missing separator after `%s', have %s",
337 			buffer, unctrl(ch));
338 		_nc_curr_token.tk_name = buffer;
339 		type = CANCEL;
340 		break;
341 
342 	    case '#':
343 		found = 0;
344 		while (isalnum(ch = next_char())) {
345 		    numbuf[found++] = ch;
346 		    if (found >= sizeof(numbuf) - 1)
347 			break;
348 		}
349 		numbuf[found] = '\0';
350 		number = strtol(numbuf, &numchk, 0);
351 		if (numchk == numbuf)
352 		    _nc_warning("no value given for `%s'", buffer);
353 		if ((*numchk != '\0') || (ch != separator))
354 		    _nc_warning("Missing separator");
355 		_nc_curr_token.tk_name = buffer;
356 		_nc_curr_token.tk_valnumber = number;
357 		type = NUMBER;
358 		break;
359 
360 	    case '=':
361 		ch = _nc_trans_string(ptr, buffer + sizeof(buffer));
362 		if (ch != separator)
363 		    _nc_warning("Missing separator");
364 		_nc_curr_token.tk_name = buffer;
365 		_nc_curr_token.tk_valstring = ptr;
366 		type = STRING;
367 		break;
368 
369 	    case EOF:
370 		type = EOF;
371 		break;
372 	    default:
373 		/* just to get rid of the compiler warning */
374 		type = UNDEF;
375 		_nc_warning("Illegal character - %s", unctrl(ch));
376 	    }
377 	}			/* end else (first_column == FALSE) */
378     }				/* end else (ch != EOF) */
379 
380   end_of_token:
381 
382 #ifdef TRACE
383     if (dot_flag == TRUE)
384 	DEBUG(8, ("Commented out "));
385 
386     if (_nc_tracing >= DEBUG_LEVEL(7)) {
387 	switch (type) {
388 	case BOOLEAN:
389 	    _tracef("Token: Boolean; name='%s'",
390 		_nc_curr_token.tk_name);
391 	    break;
392 
393 	case NUMBER:
394 	    _tracef("Token: Number;  name='%s', value=%d",
395 		_nc_curr_token.tk_name,
396 		_nc_curr_token.tk_valnumber);
397 	    break;
398 
399 	case STRING:
400 	    _tracef("Token: String;  name='%s', value=%s",
401 		_nc_curr_token.tk_name,
402 		_nc_visbuf(_nc_curr_token.tk_valstring));
403 	    break;
404 
405 	case CANCEL:
406 	    _tracef("Token: Cancel; name='%s'",
407 		_nc_curr_token.tk_name);
408 	    break;
409 
410 	case NAMES:
411 
412 	    _tracef("Token: Names; value='%s'",
413 		_nc_curr_token.tk_name);
414 	    break;
415 
416 	case EOF:
417 	    _tracef("Token: End of file");
418 	    break;
419 
420 	default:
421 	    _nc_warning("Bad token type");
422 	}
423     }
424 #endif
425 
426     if (dot_flag == TRUE)	/* if commented out, use the next one */
427 	type = _nc_get_token();
428 
429     DEBUG(3, ("token: `%s', class %d", _nc_curr_token.tk_name, type));
430 
431     return (type);
432 }
433 
434 /*
435  *	char
436  *	trans_string(ptr)
437  *
438  *	Reads characters using next_char() until encountering a separator, nl,
439  *	or end-of-file.  The returned value is the character which caused
440  *	reading to stop.  The following translations are done on the input:
441  *
442  *		^X  goes to  ctrl-X (i.e. X & 037)
443  *		{\E,\n,\r,\b,\t,\f}  go to
444  *			{ESCAPE,newline,carriage-return,backspace,tab,formfeed}
445  *		{\^,\\}  go to  {carat,backslash}
446  *		\ddd (for ddd = up to three octal digits)  goes to the character ddd
447  *
448  *		\e == \E
449  *		\0 == \200
450  *
451  */
452 
453 char
454 _nc_trans_string(char *ptr, char *last)
455 {
456     int count = 0;
457     int number;
458     int i, c;
459     chtype ch, last_ch = '\0';
460     bool ignored = FALSE;
461     bool long_warning = FALSE;
462 
463     while ((ch = c = next_char()) != (chtype) separator && c != EOF) {
464 	if (ptr == (last - 1))
465 	    break;
466 	if ((_nc_syntax == SYN_TERMCAP) && c == '\n')
467 	    break;
468 	if (ch == '^' && last_ch != '%') {
469 	    ch = c = next_char();
470 	    if (c == EOF)
471 		_nc_err_abort("Premature EOF");
472 
473 	    if (!(is7bits(ch) && isprint(ch))) {
474 		_nc_warning("Illegal ^ character - %s", unctrl(ch));
475 	    }
476 	    if (ch == '?') {
477 		*(ptr++) = '\177';
478 		if (_nc_tracing)
479 		    _nc_warning("Allow ^? as synonym for \\177");
480 	    } else {
481 		if ((ch &= 037) == 0)
482 		    ch = 128;
483 		*(ptr++) = (char) (ch);
484 	    }
485 	} else if (ch == '\\') {
486 	    ch = c = next_char();
487 	    if (c == EOF)
488 		_nc_err_abort("Premature EOF");
489 
490 	    if (ch >= '0' && ch <= '7') {
491 		number = ch - '0';
492 		for (i = 0; i < 2; i++) {
493 		    ch = c = next_char();
494 		    if (c == EOF)
495 			_nc_err_abort("Premature EOF");
496 
497 		    if (c < '0' || c > '7') {
498 			if (isdigit(c)) {
499 			    _nc_warning("Non-octal digit `%c' in \\ sequence", c);
500 			    /* allow the digit; it'll do less harm */
501 			} else {
502 			    push_back((char) c);
503 			    break;
504 			}
505 		    }
506 
507 		    number = number * 8 + c - '0';
508 		}
509 
510 		if (number == 0)
511 		    number = 0200;
512 		*(ptr++) = (char) number;
513 	    } else {
514 		switch (c) {
515 		case 'E':
516 		case 'e':
517 		    *(ptr++) = '\033';
518 		    break;
519 
520 		case 'a':
521 		    *(ptr++) = '\007';
522 		    break;
523 
524 		case 'l':
525 		case 'n':
526 		    *(ptr++) = '\n';
527 		    break;
528 
529 		case 'r':
530 		    *(ptr++) = '\r';
531 		    break;
532 
533 		case 'b':
534 		    *(ptr++) = '\010';
535 		    break;
536 
537 		case 's':
538 		    *(ptr++) = ' ';
539 		    break;
540 
541 		case 'f':
542 		    *(ptr++) = '\014';
543 		    break;
544 
545 		case 't':
546 		    *(ptr++) = '\t';
547 		    break;
548 
549 		case '\\':
550 		    *(ptr++) = '\\';
551 		    break;
552 
553 		case '^':
554 		    *(ptr++) = '^';
555 		    break;
556 
557 		case ',':
558 		    *(ptr++) = ',';
559 		    break;
560 
561 		case ':':
562 		    *(ptr++) = ':';
563 		    break;
564 
565 		case '\n':
566 		    continue;
567 
568 		default:
569 		    _nc_warning("Illegal character %s in \\ sequence",
570 			unctrl(ch));
571 		    *(ptr++) = (char) ch;
572 		}		/* endswitch (ch) */
573 	    }			/* endelse (ch < '0' ||  ch > '7') */
574 	}
575 	/* end else if (ch == '\\') */
576 	else if (ch == '\n' && (_nc_syntax == SYN_TERMINFO)) {
577 	    /* newlines embedded in a terminfo string are ignored */
578 	    ignored = TRUE;
579 	} else {
580 	    *(ptr++) = (char) ch;
581 	}
582 
583 	if (!ignored) {
584 	    last_ch = ch;
585 	    count++;
586 	}
587 	ignored = FALSE;
588 
589 	if (count > MAXCAPLEN && !long_warning) {
590 	    _nc_warning("Very long string found.  Missing separator?");
591 	    long_warning = TRUE;
592 	}
593     }				/* end while */
594 
595     *ptr = '\0';
596 
597     return (ch);
598 }
599 
600 /*
601  *	_nc_push_token()
602  *
603  *	Push a token of given type so that it will be reread by the next
604  *	get_token() call.
605  */
606 
607 void
608 _nc_push_token(int tokclass)
609 {
610     /*
611      * This implementation is kind of bogus, it will fail if we ever do
612      * more than one pushback at a time between get_token() calls.  It
613      * relies on the fact that curr_tok is static storage that nothing
614      * but get_token() touches.
615      */
616     pushtype = tokclass;
617     _nc_get_type(pushname);
618 
619     DEBUG(3, ("pushing token: `%s', class %d",
620 	    _nc_curr_token.tk_name, pushtype));
621 }
622 
623 /*
624  * Panic mode error recovery - skip everything until a "ch" is found.
625  */
626 void
627 _nc_panic_mode(char ch)
628 {
629     int c;
630 
631     for (;;) {
632 	c = next_char();
633 	if (c == ch)
634 	    return;
635 	if (c == EOF)
636 	    return;
637     }
638 }
639 
640 /*****************************************************************************
641  *
642  * Character-stream handling
643  *
644  *****************************************************************************/
645 
646 #define LEXBUFSIZ	1024
647 
648 static char *bufptr;		/* otherwise, the input buffer pointer */
649 static char *bufstart;		/* start of buffer so we can compute offsets */
650 static FILE *yyin;		/* scanner's input file descriptor */
651 
652 /*
653  *	_nc_reset_input()
654  *
655  *	Resets the input-reading routines.  Used on initialization,
656  *	or after a seek has been done.  Exactly one argument must be
657  *	non-null.
658  */
659 
660 void
661 _nc_reset_input(FILE * fp, char *buf)
662 {
663     pushtype = NO_PUSHBACK;
664     pushname[0] = '\0';
665     yyin = fp;
666     bufstart = bufptr = buf;
667     _nc_curr_file_pos = 0L;
668     if (fp != 0)
669 	_nc_curr_line = 0;
670     _nc_curr_col = 0;
671 }
672 
673 /*
674  *	int last_char()
675  *
676  *	Returns the final nonblank character on the current input buffer
677  */
678 static int
679 last_char(void)
680 {
681     size_t len = strlen(bufptr);
682     while (len--) {
683 	if (!isspace(bufptr[len]))
684 	    return bufptr[len];
685     }
686     return 0;
687 }
688 
689 /*
690  *	int next_char()
691  *
692  *	Returns the next character in the input stream.  Comments and leading
693  *	white space are stripped.
694  *
695  *	The global state variable 'firstcolumn' is set TRUE if the character
696  *	returned is from the first column of the input line.
697  *
698  *	The global variable _nc_curr_line is incremented for each new line.
699  *	The global variable _nc_curr_file_pos is set to the file offset of the
700  *	beginning of each line.
701  */
702 
703 static int
704 next_char(void)
705 {
706     if (!yyin) {
707 	if (*bufptr == '\0')
708 	    return (EOF);
709 	if (*bufptr == '\n') {
710 	    _nc_curr_line++;
711 	    _nc_curr_col = 0;
712 	}
713     } else if (!bufptr || !*bufptr) {
714 	/*
715 	 * In theory this could be recoded to do its I/O one
716 	 * character at a time, saving the buffer space.  In
717 	 * practice, this turns out to be quite hard to get
718 	 * completely right.  Try it and see.  If you succeed,
719 	 * don't forget to hack push_back() correspondingly.
720 	 */
721 	static char line[LEXBUFSIZ];
722 	size_t len;
723 
724 	do {
725 	    _nc_curr_file_pos = ftell(yyin);
726 
727 	    if ((bufstart = fgets(line, LEXBUFSIZ, yyin)) != NULL) {
728 		_nc_curr_line++;
729 		_nc_curr_col = 0;
730 	    }
731 	    bufptr = bufstart;
732 	} while
733 	    (bufstart != NULL && line[0] == '#');
734 
735 	if (bufstart == NULL)
736 	    return (EOF);
737 
738 	while (iswhite(*bufptr))
739 	    bufptr++;
740 
741 	/*
742 	 * Treat a trailing <cr><lf> the same as a <newline> so we can read
743 	 * files on OS/2, etc.
744 	 */
745 	if ((len = strlen(bufptr)) > 1) {
746 	    if (bufptr[len - 1] == '\n'
747 		&& bufptr[len - 2] == '\r') {
748 		bufptr[len - 2] = '\n';
749 		bufptr[len - 1] = '\0';
750 	    }
751 	}
752     }
753 
754     first_column = (bufptr == bufstart);
755 
756     _nc_curr_col++;
757     return (*bufptr++);
758 }
759 
760 static void
761 push_back(char c)
762 /* push a character back onto the input stream */
763 {
764     if (bufptr == bufstart)
765 	_nc_syserr_abort("Can't backspace off beginning of line");
766     *--bufptr = c;
767 }
768 
769 static long
770 stream_pos(void)
771 /* return our current character position in the input stream */
772 {
773     return (yyin ? ftell(yyin) : (bufptr ? bufptr - bufstart : 0));
774 }
775 
776 static bool
777 end_of_stream(void)
778 /* are we at end of input? */
779 {
780     return ((yyin ? feof(yyin) : (bufptr && *bufptr == '\0'))
781 	? TRUE : FALSE);
782 }
783 
784 /* comp_scan.c ends here */
785