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/*
*
* Copyright 2008 Javier Merino <cibervicho@gmail.com>
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
* Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <string.h>
#define streq(a, b) (!strcmp((a), (b)))
static void stdin_to_stream(char *buf, ssize_t r, FILE *outf) {
while (r > 0) {
if (fwrite(buf, r*sizeof(char), 1, outf) < 1) {
fprintf(stderr, "Write error\n");
exit(EXIT_FAILURE);
}
r = read(0, buf, BUFSIZ*sizeof(char));
}
if (r == -1) {
perror("read");
exit(EXIT_FAILURE);
}
}
int main(int argc, char **argv) {
ssize_t r;
int run_if_empty;
char **argv_exec;
int fds[2];
int child_status;
pid_t child_pid;
char buf[BUFSIZ];
FILE *outf;
if ((argc < 2) || ((argc == 2) && streq(argv[1], "-n"))) {
fprintf(stderr, "Usage: ifne [-n] command [args]\n");
return EXIT_FAILURE;
}
if (streq(argv[1], "-n")) {
run_if_empty = 1;
argv_exec = &argv[2];
} else {
run_if_empty = 0;
argv_exec = &argv[1];
}
r = read(0, buf, BUFSIZ*sizeof(char));
if ((r == 0) && !run_if_empty)
return EXIT_SUCCESS;
else if (r == -1) {
perror("read");
return EXIT_FAILURE;
}
if (pipe(fds)) {
perror("pipe");
return EXIT_FAILURE;
}
if (r && run_if_empty) {
/* don't run the subcommand if we read something from stdin and -n was set */
/* But write stdin to stdout so ifne -n can be piped without sucking the stream */
stdin_to_stream(buf, r, stdout);
return EXIT_SUCCESS;
}
child_pid = fork();
if (!child_pid) {
/* child process: rebind stdin and exec the subcommand */
close(fds[1]);
if (dup2(fds[0], 0)) {
perror("dup2");
return EXIT_FAILURE;
}
execvp(*argv_exec, argv_exec);
perror(*argv_exec);
close(fds[0]);
return EXIT_FAILURE;
} else if (child_pid == -1) {
perror("fork");
return EXIT_FAILURE;
}
/* Parent: write stdin to fds[1] */
close(fds[0]);
outf = fdopen(fds[1], "w");
if (! outf) {
perror("fdopen");
exit(1);
}
stdin_to_stream(buf, r, outf);
fclose(outf);
if (waitpid(child_pid, &child_status, 0) != child_pid) {
perror("waitpid");
return EXIT_FAILURE;
}
if (WIFEXITED(child_status)) {
return (WEXITSTATUS(child_status));
} else if (WIFSIGNALED(child_status)) {
raise(WTERMSIG(child_status));
return EXIT_FAILURE;
}
return EXIT_FAILURE;
}
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