442 lines
11 KiB
C
442 lines
11 KiB
C
/* filter - postprocessing of flex output through filters */
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/* This file is part of flex. */
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/* Redistribution and use in source and binary forms, with or without */
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/* modification, are permitted provided that the following conditions */
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/* are met: */
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/* 1. Redistributions of source code must retain the above copyright */
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/* notice, this list of conditions and the following disclaimer. */
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/* 2. Redistributions in binary form must reproduce the above copyright */
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/* notice, this list of conditions and the following disclaimer in the */
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/* documentation and/or other materials provided with the distribution. */
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/* Neither the name of the University nor the names of its contributors */
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/* may be used to endorse or promote products derived from this software */
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/* without specific prior written permission. */
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/* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR */
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/* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED */
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/* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR */
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/* PURPOSE. */
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#include "flexdef.h"
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static const char * check_4_gnu_m4 =
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"m4_dnl ifdef(`__gnu__', ,"
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"`errprint(Flex requires GNU M4. Set the PATH or set the M4 environment variable to its path name.)"
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" m4exit(2)')\n";
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/** global chain. */
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struct filter *output_chain = NULL;
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/* Allocate and initialize an external filter.
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* @param chain the current chain or NULL for new chain
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* @param cmd the command to execute.
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* @param ... a NULL terminated list of (const char*) arguments to command,
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* not including argv[0].
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* @return newest filter in chain
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*/
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struct filter *filter_create_ext (struct filter *chain, const char *cmd,
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...)
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{
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struct filter *f;
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int max_args;
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const char *s;
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va_list ap;
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/* allocate and initialize new filter */
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f = (struct filter *) flex_alloc (sizeof (struct filter));
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if (!f)
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flexerror (_("flex_alloc failed (f) in filter_create_ext"));
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memset (f, 0, sizeof (*f));
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f->filter_func = NULL;
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f->extra = NULL;
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f->next = NULL;
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f->argc = 0;
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if (chain != NULL) {
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/* append f to end of chain */
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while (chain->next)
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chain = chain->next;
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chain->next = f;
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}
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/* allocate argv, and populate it with the argument list. */
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max_args = 8;
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f->argv =
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(const char **) flex_alloc (sizeof (char *) *
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(max_args + 1));
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if (!f->argv)
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flexerror (_("flex_alloc failed (f->argv) in filter_create_ext"));
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f->argv[f->argc++] = cmd;
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va_start (ap, cmd);
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while ((s = va_arg (ap, const char *)) != NULL) {
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if (f->argc >= max_args) {
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max_args += 8;
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f->argv =
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(const char **) flex_realloc (f->argv,
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sizeof (char
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*) *
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(max_args +
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1));
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}
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f->argv[f->argc++] = s;
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}
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f->argv[f->argc] = NULL;
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va_end (ap);
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return f;
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}
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/* Allocate and initialize an internal filter.
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* @param chain the current chain or NULL for new chain
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* @param filter_func The function that will perform the filtering.
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* filter_func should return 0 if successful, and -1
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* if an error occurs -- or it can simply exit().
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* @param extra optional user-defined data to pass to the filter.
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* @return newest filter in chain
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*/
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struct filter *filter_create_int (struct filter *chain,
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int (*filter_func) (struct filter *),
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void *extra)
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{
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struct filter *f;
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/* allocate and initialize new filter */
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f = (struct filter *) flex_alloc (sizeof (struct filter));
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if (!f)
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flexerror (_("flex_alloc failed in filter_create_int"));
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memset (f, 0, sizeof (*f));
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f->next = NULL;
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f->argc = 0;
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f->argv = NULL;
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f->filter_func = filter_func;
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f->extra = extra;
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if (chain != NULL) {
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/* append f to end of chain */
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while (chain->next)
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chain = chain->next;
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chain->next = f;
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}
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return f;
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}
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/** Fork and exec entire filter chain.
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* @param chain The head of the chain.
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* @return true on success.
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*/
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bool filter_apply_chain (struct filter * chain)
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{
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int pid, pipes[2];
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/* Tricky recursion, since we want to begin the chain
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* at the END. Why? Because we need all the forked processes
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* to be children of the main flex process.
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*/
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if (chain)
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filter_apply_chain (chain->next);
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else
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return true;
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/* Now we are the right-most unprocessed link in the chain.
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*/
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fflush (stdout);
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fflush (stderr);
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if (pipe (pipes) == -1)
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flexerror (_("pipe failed"));
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if ((pid = fork ()) == -1)
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flexerror (_("fork failed"));
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if (pid == 0) {
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/* child */
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/* We need stdin (the FILE* stdin) to connect to this new pipe.
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* There is no portable way to set stdin to a new file descriptor,
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* as stdin is not an lvalue on some systems (BSD).
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* So we dup the new pipe onto the stdin descriptor and use a no-op fseek
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* to sync the stream. This is a Hail Mary situation. It seems to work.
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*/
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close (pipes[1]);
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clearerr(stdin);
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if (dup2 (pipes[0], fileno (stdin)) == -1)
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flexfatal (_("dup2(pipes[0],0)"));
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close (pipes[0]);
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fseek (stdin, 0, SEEK_CUR);
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/* run as a filter, either internally or by exec */
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if (chain->filter_func) {
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int r;
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if ((r = chain->filter_func (chain)) == -1)
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flexfatal (_("filter_func failed"));
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exit (0);
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}
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else {
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execvp (chain->argv[0],
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(char **const) (chain->argv));
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lerrsf_fatal ( _("exec of %s failed"),
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chain->argv[0]);
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}
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exit (1);
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}
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/* Parent */
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close (pipes[0]);
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if (dup2 (pipes[1], fileno (stdout)) == -1)
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flexfatal (_("dup2(pipes[1],1)"));
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close (pipes[1]);
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fseek (stdout, 0, SEEK_CUR);
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return true;
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}
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/** Truncate the chain to max_len number of filters.
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* @param chain the current chain.
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* @param max_len the maximum length of the chain.
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* @return the resulting length of the chain.
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*/
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int filter_truncate (struct filter *chain, int max_len)
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{
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int len = 1;
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if (!chain)
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return 0;
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while (chain->next && len < max_len) {
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chain = chain->next;
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++len;
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}
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chain->next = NULL;
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return len;
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}
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/** Splits the chain in order to write to a header file.
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* Similar in spirit to the 'tee' program.
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* The header file name is in extra.
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* @return 0 (zero) on success, and -1 on failure.
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*/
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int filter_tee_header (struct filter *chain)
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{
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/* This function reads from stdin and writes to both the C file and the
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* header file at the same time.
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*/
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const int readsz = 512;
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char *buf;
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int to_cfd = -1;
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FILE *to_c = NULL, *to_h = NULL;
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bool write_header;
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write_header = (chain->extra != NULL);
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/* Store a copy of the stdout pipe, which is already piped to C file
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* through the running chain. Then create a new pipe to the H file as
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* stdout, and fork the rest of the chain again.
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*/
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if ((to_cfd = dup (1)) == -1)
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flexfatal (_("dup(1) failed"));
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to_c = fdopen (to_cfd, "w");
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if (write_header) {
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if (freopen ((char *) chain->extra, "w", stdout) == NULL)
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flexfatal (_("freopen(headerfilename) failed"));
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filter_apply_chain (chain->next);
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to_h = stdout;
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}
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/* Now to_c is a pipe to the C branch, and to_h is a pipe to the H branch.
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*/
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if (write_header) {
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fputs (check_4_gnu_m4, to_h);
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fputs ("m4_changecom`'m4_dnl\n", to_h);
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fputs ("m4_changequote`'m4_dnl\n", to_h);
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fputs ("m4_changequote([[,]])[[]]m4_dnl\n", to_h);
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fputs ("m4_define([[M4_YY_NOOP]])[[]]m4_dnl\n", to_h);
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fputs ("m4_define( [[M4_YY_IN_HEADER]],[[]])m4_dnl\n",
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to_h);
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fprintf (to_h, "#ifndef %sHEADER_H\n", prefix);
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fprintf (to_h, "#define %sHEADER_H 1\n", prefix);
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fprintf (to_h, "#define %sIN_HEADER 1\n\n", prefix);
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fprintf (to_h,
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"m4_define( [[M4_YY_OUTFILE_NAME]],[[%s]])m4_dnl\n",
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headerfilename ? headerfilename : "<stdout>");
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}
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fputs (check_4_gnu_m4, to_c);
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fputs ("m4_changecom`'m4_dnl\n", to_c);
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fputs ("m4_changequote`'m4_dnl\n", to_c);
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fputs ("m4_changequote([[,]])[[]]m4_dnl\n", to_c);
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fputs ("m4_define([[M4_YY_NOOP]])[[]]m4_dnl\n", to_c);
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fprintf (to_c, "m4_define( [[M4_YY_OUTFILE_NAME]],[[%s]])m4_dnl\n",
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outfilename ? outfilename : "<stdout>");
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buf = (char *) flex_alloc (readsz);
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if (!buf)
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flexerror (_("flex_alloc failed in filter_tee_header"));
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while (fgets (buf, readsz, stdin)) {
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fputs (buf, to_c);
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if (write_header)
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fputs (buf, to_h);
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}
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if (write_header) {
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fprintf (to_h, "\n");
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/* write a fake line number. It will get fixed by the linedir filter. */
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fprintf (to_h, "#line 4000 \"M4_YY_OUTFILE_NAME\"\n");
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fprintf (to_h, "#undef %sIN_HEADER\n", prefix);
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fprintf (to_h, "#endif /* %sHEADER_H */\n", prefix);
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fputs ("m4_undefine( [[M4_YY_IN_HEADER]])m4_dnl\n", to_h);
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fflush (to_h);
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if (ferror (to_h))
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lerrsf (_("error writing output file %s"),
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(char *) chain->extra);
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else if (fclose (to_h))
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lerrsf (_("error closing output file %s"),
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(char *) chain->extra);
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}
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fflush (to_c);
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if (ferror (to_c))
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lerrsf (_("error writing output file %s"),
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outfilename ? outfilename : "<stdout>");
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else if (fclose (to_c))
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lerrsf (_("error closing output file %s"),
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outfilename ? outfilename : "<stdout>");
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while (wait (0) > 0) ;
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exit (0);
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return 0;
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}
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/** Adjust the line numbers in the #line directives of the generated scanner.
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* After the m4 expansion, the line numbers are incorrect since the m4 macros
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* can add or remove lines. This only adjusts line numbers for generated code,
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* not user code. This also happens to be a good place to squeeze multiple
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* blank lines into a single blank line.
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*/
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int filter_fix_linedirs (struct filter *chain)
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{
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char *buf;
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const int readsz = 512;
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int lineno = 1;
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bool in_gen = true; /* in generated code */
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bool last_was_blank = false;
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if (!chain)
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return 0;
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buf = (char *) flex_alloc (readsz);
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if (!buf)
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flexerror (_("flex_alloc failed in filter_fix_linedirs"));
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while (fgets (buf, readsz, stdin)) {
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regmatch_t m[10];
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/* Check for #line directive. */
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if (buf[0] == '#'
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&& regexec (®ex_linedir, buf, 3, m, 0) == 0) {
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int num;
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char *fname;
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/* extract the line number and filename */
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num = regmatch_strtol (&m[1], buf, NULL, 0);
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fname = regmatch_dup (&m[2], buf);
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if (strcmp (fname,
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outfilename ? outfilename : "<stdout>")
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== 0
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|| strcmp (fname,
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headerfilename ? headerfilename : "<stdout>")
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== 0) {
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char *s1, *s2;
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char filename[MAXLINE];
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s1 = fname;
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s2 = filename;
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while ((s2 - filename) < (MAXLINE - 1) && *s1) {
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/* Escape the backslash */
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if (*s1 == '\\')
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*s2++ = '\\';
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/* Escape the double quote */
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if (*s1 == '\"')
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*s2++ = '\\';
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/* Copy the character as usual */
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*s2++ = *s1++;
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}
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*s2 = '\0';
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/* Adjust the line directives. */
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in_gen = true;
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snprintf (buf, readsz, "#line %d \"%s\"\n",
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lineno + 1, filename);
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}
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else {
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/* it's a #line directive for code we didn't write */
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in_gen = false;
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}
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free (fname);
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last_was_blank = false;
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}
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/* squeeze blank lines from generated code */
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else if (in_gen
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&& regexec (®ex_blank_line, buf, 0, NULL,
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0) == 0) {
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if (last_was_blank)
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continue;
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else
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last_was_blank = true;
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}
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else {
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/* it's a line of normal, non-empty code. */
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last_was_blank = false;
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}
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fputs (buf, stdout);
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lineno++;
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}
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fflush (stdout);
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if (ferror (stdout))
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lerrsf (_("error writing output file %s"),
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outfilename ? outfilename : "<stdout>");
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else if (fclose (stdout))
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lerrsf (_("error closing output file %s"),
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outfilename ? outfilename : "<stdout>");
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return 0;
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}
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/* vim:set expandtab cindent tabstop=4 softtabstop=4 shiftwidth=4 textwidth=0: */
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