1/* $NetBSD: filter.c,v 1.1.1.1 2009/10/26 00:26:00 christos Exp $ */ 2 3/* filter - postprocessing of flex output through filters */ 4 5/* This file is part of flex. */ 6 7/* Redistribution and use in source and binary forms, with or without */ 8/* modification, are permitted provided that the following conditions */ 9/* are met: */ 10 11/* 1. Redistributions of source code must retain the above copyright */ 12/* notice, this list of conditions and the following disclaimer. */ 13/* 2. Redistributions in binary form must reproduce the above copyright */ 14/* notice, this list of conditions and the following disclaimer in the */ 15/* documentation and/or other materials provided with the distribution. */ 16 17/* Neither the name of the University nor the names of its contributors */ 18/* may be used to endorse or promote products derived from this software */ 19/* without specific prior written permission. */ 20 21/* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR */ 22/* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED */ 23/* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR */ 24/* PURPOSE. */ 25 26#include "flexdef.h" 27static const char * check_4_gnu_m4 = 28 "m4_dnl ifdef(`__gnu__', ," 29 "`errprint(Flex requires GNU M4. Set the PATH or set the M4 environment variable to its path name.)" 30 " m4exit(2)')\n"; 31 32 33/** global chain. */ 34struct filter *output_chain = NULL; 35 36/* Allocate and initialize an external filter. 37 * @param chain the current chain or NULL for new chain 38 * @param cmd the command to execute. 39 * @param ... a NULL terminated list of (const char*) arguments to command, 40 * not including argv[0]. 41 * @return newest filter in chain 42 */ 43struct filter *filter_create_ext (struct filter *chain, const char *cmd, 44 ...) 45{ 46 struct filter *f; 47 int max_args; 48 const char *s; 49 va_list ap; 50 51 /* allocate and initialize new filter */ 52 f = (struct filter *) flex_alloc (sizeof (struct filter)); 53 memset (f, 0, sizeof (*f)); 54 f->filter_func = NULL; 55 f->extra = NULL; 56 f->next = NULL; 57 f->argc = 0; 58 59 if (chain != NULL) { 60 /* append f to end of chain */ 61 while (chain->next) 62 chain = chain->next; 63 chain->next = f; 64 } 65 66 67 /* allocate argv, and populate it with the argument list. */ 68 max_args = 8; 69 f->argv = 70 (const char **) flex_alloc (sizeof (char *) * 71 (max_args + 1)); 72 f->argv[f->argc++] = cmd; 73 74 va_start (ap, cmd); 75 while ((s = va_arg (ap, const char *)) != NULL) { 76 if (f->argc >= max_args) { 77 max_args += 8; 78 f->argv = 79 (const char **) flex_realloc (f->argv, 80 sizeof (char 81 *) * 82 (max_args + 83 1)); 84 } 85 f->argv[f->argc++] = s; 86 } 87 f->argv[f->argc] = NULL; 88 89 va_end (ap); 90 return f; 91} 92 93/* Allocate and initialize an internal filter. 94 * @param chain the current chain or NULL for new chain 95 * @param filter_func The function that will perform the filtering. 96 * filter_func should return 0 if successful, and -1 97 * if an error occurs -- or it can simply exit(). 98 * @param extra optional user-defined data to pass to the filter. 99 * @return newest filter in chain 100 */ 101struct filter *filter_create_int (struct filter *chain, 102 int (*filter_func) (struct filter *), 103 void *extra) 104{ 105 struct filter *f; 106 107 /* allocate and initialize new filter */ 108 f = (struct filter *) flex_alloc (sizeof (struct filter)); 109 memset (f, 0, sizeof (*f)); 110 f->next = NULL; 111 f->argc = 0; 112 f->argv = NULL; 113 114 f->filter_func = filter_func; 115 f->extra = extra; 116 117 if (chain != NULL) { 118 /* append f to end of chain */ 119 while (chain->next) 120 chain = chain->next; 121 chain->next = f; 122 } 123 124 return f; 125} 126 127/** Fork and exec entire filter chain. 128 * @param chain The head of the chain. 129 * @return true on success. 130 */ 131bool filter_apply_chain (struct filter * chain) 132{ 133 int pid, pipes[2]; 134 135 /* Tricky recursion, since we want to begin the chain 136 * at the END. Why? Because we need all the forked processes 137 * to be children of the main flex process. 138 */ 139 if (chain) 140 filter_apply_chain (chain->next); 141 else 142 return true; 143 144 /* Now we are the right-most unprocessed link in the chain. 145 */ 146 147 fflush (stdout); 148 fflush (stderr); 149 150 if (pipe (pipes) == -1) 151 flexerror (_("pipe failed")); 152 153 if ((pid = fork ()) == -1) 154 flexerror (_("fork failed")); 155 156 if (pid == 0) { 157 /* child */ 158 159 /* We need stdin (the FILE* stdin) to connect to this new pipe. 160 * There is no portable way to set stdin to a new file descriptor, 161 * as stdin is not an lvalue on some systems (BSD). 162 * So we dup the new pipe onto the stdin descriptor and use a no-op fseek 163 * to sync the stream. This is a Hail Mary situation. It seems to work. 164 */ 165 close (pipes[1]); 166 if (dup2 (pipes[0], fileno (stdin)) == -1) 167 flexfatal (_("dup2(pipes[0],0)")); 168 close (pipes[0]); 169 fseek (stdin, 0, SEEK_CUR); 170 171 /* run as a filter, either internally or by exec */ 172 if (chain->filter_func) { 173 int r; 174 175 if ((r = chain->filter_func (chain)) == -1) 176 flexfatal (_("filter_func failed")); 177 exit (0); 178 } 179 else { 180 execvp (chain->argv[0], 181 (char **const) (chain->argv)); 182 flexfatal (_("exec failed")); 183 } 184 185 exit (1); 186 } 187 188 /* Parent */ 189 close (pipes[0]); 190 if (dup2 (pipes[1], fileno (stdout)) == -1) 191 flexfatal (_("dup2(pipes[1],1)")); 192 close (pipes[1]); 193 fseek (stdout, 0, SEEK_CUR); 194 195 return true; 196} 197 198/** Truncate the chain to max_len number of filters. 199 * @param chain the current chain. 200 * @param max_len the maximum length of the chain. 201 * @return the resulting length of the chain. 202 */ 203int filter_truncate (struct filter *chain, int max_len) 204{ 205 int len = 1; 206 207 if (!chain) 208 return 0; 209 210 while (chain->next && len < max_len) { 211 chain = chain->next; 212 ++len; 213 } 214 215 chain->next = NULL; 216 return len; 217} 218 219/** Splits the chain in order to write to a header file. 220 * Similar in spirit to the 'tee' program. 221 * The header file name is in extra. 222 * @return 0 (zero) on success, and -1 on failure. 223 */ 224int filter_tee_header (struct filter *chain) 225{ 226 /* This function reads from stdin and writes to both the C file and the 227 * header file at the same time. 228 */ 229 230 const int readsz = 512; 231 char *buf; 232 int to_cfd = -1; 233 FILE *to_c = NULL, *to_h = NULL; 234 bool write_header; 235 236 write_header = (chain->extra != NULL); 237 238 /* Store a copy of the stdout pipe, which is already piped to C file 239 * through the running chain. Then create a new pipe to the H file as 240 * stdout, and fork the rest of the chain again. 241 */ 242 243 if ((to_cfd = dup (1)) == -1) 244 flexfatal (_("dup(1) failed")); 245 to_c = fdopen (to_cfd, "w"); 246 247 if (write_header) { 248 if (freopen ((char *) chain->extra, "w", stdout) == NULL) 249 flexfatal (_("freopen(headerfilename) failed")); 250 251 filter_apply_chain (chain->next); 252 to_h = stdout; 253 } 254 255 /* Now to_c is a pipe to the C branch, and to_h is a pipe to the H branch. 256 */ 257 258 if (write_header) { 259 fputs (check_4_gnu_m4, to_h); 260 fputs ("m4_changecom`'m4_dnl\n", to_h); 261 fputs ("m4_changequote`'m4_dnl\n", to_h); 262 fputs ("m4_changequote([[,]])[[]]m4_dnl\n", to_h); 263 fputs ("m4_define([[M4_YY_NOOP]])[[]]m4_dnl\n", to_h); 264 fputs ("m4_define( [[M4_YY_IN_HEADER]],[[]])m4_dnl\n", 265 to_h); 266 fprintf (to_h, "#ifndef %sHEADER_H\n", prefix); 267 fprintf (to_h, "#define %sHEADER_H 1\n", prefix); 268 fprintf (to_h, "#define %sIN_HEADER 1\n\n", prefix); 269 fprintf (to_h, 270 "m4_define( [[M4_YY_OUTFILE_NAME]],[[%s]])m4_dnl\n", 271 headerfilename ? headerfilename : "<stdout>"); 272 273 } 274 275 fputs (check_4_gnu_m4, to_c); 276 fputs ("m4_changecom`'m4_dnl\n", to_c); 277 fputs ("m4_changequote`'m4_dnl\n", to_c); 278 fputs ("m4_changequote([[,]])[[]]m4_dnl\n", to_c); 279 fputs ("m4_define([[M4_YY_NOOP]])[[]]m4_dnl\n", to_c); 280 fprintf (to_c, "m4_define( [[M4_YY_OUTFILE_NAME]],[[%s]])m4_dnl\n", 281 outfilename ? outfilename : "<stdout>"); 282 283 buf = (char *) flex_alloc (readsz); 284 while (fgets (buf, readsz, stdin)) { 285 fputs (buf, to_c); 286 if (write_header) 287 fputs (buf, to_h); 288 } 289 290 if (write_header) { 291 fprintf (to_h, "\n"); 292 293 /* write a fake line number. It will get fixed by the linedir filter. */ 294 fprintf (to_h, "#line 4000 \"M4_YY_OUTFILE_NAME\"\n"); 295 296 fprintf (to_h, "#undef %sIN_HEADER\n", prefix); 297 fprintf (to_h, "#endif /* %sHEADER_H */\n", prefix); 298 fputs ("m4_undefine( [[M4_YY_IN_HEADER]])m4_dnl\n", to_h); 299 300 fflush (to_h); 301 if (ferror (to_h)) 302 lerrsf (_("error writing output file %s"), 303 (char *) chain->extra); 304 305 else if (fclose (to_h)) 306 lerrsf (_("error closing output file %s"), 307 (char *) chain->extra); 308 } 309 310 fflush (to_c); 311 if (ferror (to_c)) 312 lerrsf (_("error writing output file %s"), 313 outfilename ? outfilename : "<stdout>"); 314 315 else if (fclose (to_c)) 316 lerrsf (_("error closing output file %s"), 317 outfilename ? outfilename : "<stdout>"); 318 319 while (wait (0) > 0) ; 320 321 exit (0); 322 return 0; 323} 324 325/** Adjust the line numbers in the #line directives of the generated scanner. 326 * After the m4 expansion, the line numbers are incorrect since the m4 macros 327 * can add or remove lines. This only adjusts line numbers for generated code, 328 * not user code. This also happens to be a good place to squeeze multiple 329 * blank lines into a single blank line. 330 */ 331int filter_fix_linedirs (struct filter *chain) 332{ 333 char *buf; 334 const int readsz = 512; 335 int lineno = 1; 336 bool in_gen = true; /* in generated code */ 337 bool last_was_blank = false; 338 339 if (!chain) 340 return 0; 341 342 buf = (char *) flex_alloc (readsz); 343 344 while (fgets (buf, readsz, stdin)) { 345 346 regmatch_t m[10]; 347 348 /* Check for #line directive. */ 349 if (buf[0] == '#' 350 && regexec (®ex_linedir, buf, 3, m, 0) == 0) { 351 352 int num; 353 char *fname; 354 355 /* extract the line number and filename */ 356 num = regmatch_strtol (&m[1], buf, NULL, 0); 357 fname = regmatch_dup (&m[2], buf); 358 359 if (strcmp (fname, 360 outfilename ? outfilename : "<stdout>") 361 == 0 362 || strcmp (fname, 363 headerfilename ? headerfilename : "<stdout>") 364 == 0) { 365 366 char *s1, *s2; 367 char filename[MAXLINE]; 368 369 s1 = fname; 370 s2 = filename; 371 372 while ((s2 - filename) < (MAXLINE - 1) && *s1) { 373 /* Escape the backslash */ 374 if (*s1 == '\\') 375 *s2++ = '\\'; 376 /* Escape the double quote */ 377 if (*s1 == '\"') 378 *s2++ = '\\'; 379 /* Copy the character as usual */ 380 *s2++ = *s1++; 381 } 382 383 *s2 = '\0'; 384 385 /* Adjust the line directives. */ 386 in_gen = true; 387 snprintf (buf, readsz, "#line %d \"%s\"\n", 388 lineno + 1, filename); 389 } 390 else { 391 /* it's a #line directive for code we didn't write */ 392 in_gen = false; 393 } 394 395 free (fname); 396 last_was_blank = false; 397 } 398 399 /* squeeze blank lines from generated code */ 400 else if (in_gen 401 && regexec (®ex_blank_line, buf, 0, NULL, 402 0) == 0) { 403 if (last_was_blank) 404 continue; 405 else 406 last_was_blank = true; 407 } 408 409 else { 410 /* it's a line of normal, non-empty code. */ 411 last_was_blank = false; 412 } 413 414 fputs (buf, stdout); 415 lineno++; 416 } 417 fflush (stdout); 418 if (ferror (stdout)) 419 lerrsf (_("error writing output file %s"), 420 outfilename ? outfilename : "<stdout>"); 421 422 else if (fclose (stdout)) 423 lerrsf (_("error closing output file %s"), 424 outfilename ? outfilename : "<stdout>"); 425 426 return 0; 427} 428 429/* vim:set expandtab cindent tabstop=4 softtabstop=4 shiftwidth=4 textwidth=0: */ 430