1 /* filter - postprocessing of flex output through filters */
3 /* This file is part of flex. */
5 /* Redistribution and use in source and binary forms, with or without */
6 /* modification, are permitted provided that the following conditions */
9 /* 1. Redistributions of source code must retain the above copyright */
10 /* notice, this list of conditions and the following disclaimer. */
11 /* 2. Redistributions in binary form must reproduce the above copyright */
12 /* notice, this list of conditions and the following disclaimer in the */
13 /* documentation and/or other materials provided with the distribution. */
15 /* Neither the name of the University nor the names of its contributors */
16 /* may be used to endorse or promote products derived from this software */
17 /* without specific prior written permission. */
19 /* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR */
20 /* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED */
21 /* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR */
25 static const char * check_4_gnu_m4 =
26 "m4_dnl ifdef(`__gnu__', ,"
27 "`errprint(Flex requires GNU M4. Set the PATH or set the M4 environment variable to its path name.)"
32 struct filter *output_chain = NULL;
34 /* Allocate and initialize an external filter.
35 * @param chain the current chain or NULL for new chain
36 * @param cmd the command to execute.
37 * @param ... a NULL terminated list of (const char*) arguments to command,
38 * not including argv[0].
39 * @return newest filter in chain
41 struct filter *filter_create_ext (struct filter *chain, const char *cmd,
49 /* allocate and initialize new filter */
50 f = malloc(sizeof(struct filter));
52 flexerror(_("malloc failed (f) in filter_create_ext"));
53 memset (f, 0, sizeof (*f));
54 f->filter_func = NULL;
60 /* append f to end of chain */
67 /* allocate argv, and populate it with the argument list. */
69 f->argv = malloc(sizeof(char *) * (size_t) (max_args + 1));
71 flexerror(_("malloc failed (f->argv) in filter_create_ext"));
72 f->argv[f->argc++] = cmd;
75 while ((s = va_arg (ap, const char *)) != NULL) {
76 if (f->argc >= max_args) {
78 f->argv = realloc(f->argv, sizeof(char*) * (size_t) (max_args + 1));
80 f->argv[f->argc++] = s;
82 f->argv[f->argc] = NULL;
88 /* Allocate and initialize an internal filter.
89 * @param chain the current chain or NULL for new chain
90 * @param filter_func The function that will perform the filtering.
91 * filter_func should return 0 if successful, and -1
92 * if an error occurs -- or it can simply exit().
93 * @param extra optional user-defined data to pass to the filter.
94 * @return newest filter in chain
96 struct filter *filter_create_int (struct filter *chain,
97 int (*filter_func) (struct filter *),
102 /* allocate and initialize new filter */
103 f = malloc(sizeof(struct filter));
105 flexerror(_("malloc failed in filter_create_int"));
106 memset (f, 0, sizeof (*f));
111 f->filter_func = filter_func;
115 /* append f to end of chain */
124 /** Fork and exec entire filter chain.
125 * @param chain The head of the chain.
126 * @return true on success.
128 bool filter_apply_chain (struct filter * chain)
133 /* Tricky recursion, since we want to begin the chain
134 * at the END. Why? Because we need all the forked processes
135 * to be children of the main flex process.
138 filter_apply_chain (chain->next);
142 /* Now we are the right-most unprocessed link in the chain.
149 if (pipe (pipes) == -1)
150 flexerror (_("pipe failed"));
152 if ((pid = fork ()) == -1)
153 flexerror (_("fork failed"));
158 /* We need stdin (the FILE* stdin) to connect to this new pipe.
159 * There is no portable way to set stdin to a new file descriptor,
160 * as stdin is not an lvalue on some systems (BSD).
161 * So we dup the new pipe onto the stdin descriptor and use a no-op fseek
162 * to sync the stream. This is a Hail Mary situation. It seems to work.
166 if (dup2 (pipes[0], fileno (stdin)) == -1)
167 flexfatal (_("dup2(pipes[0],0)"));
169 fseek (stdin, 0, SEEK_CUR);
170 ungetc(' ', stdin); /* still an evil hack, but one that works better */
171 (void)fgetc(stdin); /* on NetBSD than the fseek attempt does */
173 /* run as a filter, either internally or by exec */
174 if (chain->filter_func) {
177 if ((r = chain->filter_func (chain)) == -1)
178 flexfatal (_("filter_func failed"));
182 execvp (chain->argv[0],
183 (char **const) (chain->argv));
184 lerr_fatal ( _("exec of %s failed"),
193 if (dup2 (pipes[1], fileno (stdout)) == -1)
194 flexfatal (_("dup2(pipes[1],1)"));
196 fseek (stdout, 0, SEEK_CUR);
201 /** Truncate the chain to max_len number of filters.
202 * @param chain the current chain.
203 * @param max_len the maximum length of the chain.
204 * @return the resulting length of the chain.
206 int filter_truncate (struct filter *chain, int max_len)
213 while (chain->next && len < max_len) {
222 /** Splits the chain in order to write to a header file.
223 * Similar in spirit to the 'tee' program.
224 * The header file name is in extra.
225 * @return 0 (zero) on success, and -1 on failure.
227 int filter_tee_header (struct filter *chain)
229 /* This function reads from stdin and writes to both the C file and the
230 * header file at the same time.
233 const int readsz = 512;
236 FILE *to_c = NULL, *to_h = NULL;
239 write_header = (chain->extra != NULL);
241 /* Store a copy of the stdout pipe, which is already piped to C file
242 * through the running chain. Then create a new pipe to the H file as
243 * stdout, and fork the rest of the chain again.
246 if ((to_cfd = dup (1)) == -1)
247 flexfatal (_("dup(1) failed"));
248 to_c = fdopen (to_cfd, "w");
251 if (freopen ((char *) chain->extra, "w", stdout) == NULL)
252 flexfatal (_("freopen(headerfilename) failed"));
254 filter_apply_chain (chain->next);
258 /* Now to_c is a pipe to the C branch, and to_h is a pipe to the H branch.
262 fputs (check_4_gnu_m4, to_h);
263 fputs ("m4_changecom`'m4_dnl\n", to_h);
264 fputs ("m4_changequote`'m4_dnl\n", to_h);
265 fputs ("m4_changequote([[,]])[[]]m4_dnl\n", to_h);
266 fputs ("m4_define([[M4_YY_NOOP]])[[]]m4_dnl\n", to_h);
267 fputs ("m4_define( [[M4_YY_IN_HEADER]],[[]])m4_dnl\n",
269 fprintf (to_h, "#ifndef %sHEADER_H\n", prefix);
270 fprintf (to_h, "#define %sHEADER_H 1\n", prefix);
271 fprintf (to_h, "#define %sIN_HEADER 1\n\n", prefix);
273 "m4_define( [[M4_YY_OUTFILE_NAME]],[[%s]])m4_dnl\n",
274 headerfilename ? headerfilename : "<stdout>");
278 fputs (check_4_gnu_m4, to_c);
279 fputs ("m4_changecom`'m4_dnl\n", to_c);
280 fputs ("m4_changequote`'m4_dnl\n", to_c);
281 fputs ("m4_changequote([[,]])[[]]m4_dnl\n", to_c);
282 fputs ("m4_define([[M4_YY_NOOP]])[[]]m4_dnl\n", to_c);
283 fprintf (to_c, "m4_define( [[M4_YY_OUTFILE_NAME]],[[%s]])m4_dnl\n",
284 outfilename ? outfilename : "<stdout>");
286 buf = malloc((size_t) readsz);
288 flexerror(_("malloc failed in filter_tee_header"));
289 while (fgets (buf, readsz, stdin)) {
296 fprintf (to_h, "\n");
298 /* write a fake line number. It will get fixed by the linedir filter. */
300 fprintf (to_h, "#line 4000 \"M4_YY_OUTFILE_NAME\"\n");
302 fprintf (to_h, "#undef %sIN_HEADER\n", prefix);
303 fprintf (to_h, "#endif /* %sHEADER_H */\n", prefix);
304 fputs ("m4_undefine( [[M4_YY_IN_HEADER]])m4_dnl\n", to_h);
308 lerr (_("error writing output file %s"),
309 (char *) chain->extra);
311 else if (fclose (to_h))
312 lerr (_("error closing output file %s"),
313 (char *) chain->extra);
318 lerr (_("error writing output file %s"),
319 outfilename ? outfilename : "<stdout>");
321 else if (fclose (to_c))
322 lerr (_("error closing output file %s"),
323 outfilename ? outfilename : "<stdout>");
325 while (wait (0) > 0) ;
331 /** Adjust the line numbers in the #line directives of the generated scanner.
332 * After the m4 expansion, the line numbers are incorrect since the m4 macros
333 * can add or remove lines. This only adjusts line numbers for generated code,
334 * not user code. This also happens to be a good place to squeeze multiple
335 * blank lines into a single blank line.
337 int filter_fix_linedirs (struct filter *chain)
340 const size_t readsz = 512;
342 bool in_gen = true; /* in generated code */
343 bool last_was_blank = false;
348 buf = malloc(readsz);
350 flexerror(_("malloc failed in filter_fix_linedirs"));
352 while (fgets (buf, (int) readsz, stdin)) {
356 /* Check for #line directive. */
358 && regexec (®ex_linedir, buf, 3, m, 0) == 0) {
362 /* extract the line number and filename */
363 fname = regmatch_dup (&m[2], buf);
366 outfilename ? outfilename : "<stdout>")
369 headerfilename ? headerfilename : "<stdout>")
373 char filename[MAXLINE];
378 while ((s2 - filename) < (MAXLINE - 1) && *s1) {
379 /* Escape the backslash */
382 /* Escape the double quote */
385 /* Copy the character as usual */
391 /* Adjust the line directives. */
393 snprintf (buf, readsz, "#line %d \"%s\"\n",
397 /* it's a #line directive for code we didn't write */
402 last_was_blank = false;
405 /* squeeze blank lines from generated code */
407 && regexec (®ex_blank_line, buf, 0, NULL,
412 last_was_blank = true;
416 /* it's a line of normal, non-empty code. */
417 last_was_blank = false;
425 lerr (_("error writing output file %s"),
426 outfilename ? outfilename : "<stdout>");
428 else if (fclose (stdout))
429 lerr (_("error closing output file %s"),
430 outfilename ? outfilename : "<stdout>");
435 /* vim:set expandtab cindent tabstop=4 softtabstop=4 shiftwidth=4 textwidth=0: */