/* one-time initialization. Should be called before any sf_ functions. */
void
sf_init (void)
{
assert(_sf_stk == NULL);
_sf_stk = (scanflags_t*) flex_alloc ( sizeof(scanflags_t) * (_sf_max = 32));
if (!_sf_stk)
lerr_fatal(_("Unable to allocate %zu of stack"), sizeof(scanflags_t));
_sf_stk[_sf_top_ix] = 0;
}
/** Fork and exec entire filter chain.
* @param chain The head of the chain.
* @return true on success.
*/
bool filter_apply_chain (struct filter * chain)
{
int pid, pipes[2];
/* Tricky recursion, since we want to begin the chain
* at the END. Why? Because we need all the forked processes
* to be children of the main flex process.
*/
if (chain)
filter_apply_chain (chain->next);
else
return true;
/* Now we are the right-most unprocessed link in the chain.
*/
fflush (stdout);
fflush (stderr);
if (pipe (pipes) == -1)
flexerror (_("pipe failed"));
if ((pid = fork ()) == -1)
flexerror (_("fork failed"));
if (pid == 0) {
/* child */
/* We need stdin (the FILE* stdin) to connect to this new pipe.
* There is no portable way to set stdin to a new file descriptor,
* as stdin is not an lvalue on some systems (BSD).
* So we dup the new pipe onto the stdin descriptor and use a no-op fseek
* to sync the stream. This is a Hail Mary situation. It seems to work.
*/
close (pipes[1]);
clearerr(stdin);
if (dup2 (pipes[0], fileno (stdin)) == -1)
flexfatal (_("dup2(pipes[0],0)"));
close (pipes[0]);
fseek (stdin, 0, SEEK_CUR);
ungetc(' ', stdin); /* still an evil hack, but one that works better */
(void)fgetc(stdin); /* on NetBSD than the fseek attempt does */
/* run as a filter, either internally or by exec */
if (chain->filter_func) {
int r;
if ((r = chain->filter_func (chain)) == -1)
flexfatal (_("filter_func failed"));
exit (0);
}
else {
execvp (chain->argv[0],
(char **const) (chain->argv));
lerr_fatal ( _("exec of %s failed"),
chain->argv[0]);
}
exit (1);
}
/* Parent */
close (pipes[0]);
if (dup2 (pipes[1], fileno (stdout)) == -1)
flexfatal (_("dup2(pipes[1],1)"));
close (pipes[1]);
fseek (stdout, 0, SEEK_CUR);
return true;
}