wait_for_file.c

/* vim: foldmethod=marker
 * {{{ License header: MIT
 * Copyright (c) 2014 Till Maas <opensource@till.name>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 }}}*/

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>

/* USAGE ${0} WAITFILE COMMAND COMMANDARGS
 * Execute COMMAND with COMMANDARGS and kill it when WAITFILE exists
 */
int main(int argc, char** argv) {
    pid_t pid, ppid, pgid;
    int res;
    struct stat buf;
    char* waitfile;

    /* Create a new process group to be able to kill all processes */
    pgid = setsid();
    if (pgid == -1) {
        perror("pgid");
        return -1;
    }
    pid = fork();
    if (pid == 0) {
        waitfile = argv[1];
        /* Wait until waitfile exists */
        while (1) {
            if ((res = stat(waitfile, &buf)) == -1) {
                sleep(1);
            } else {
                break;
            }
        }
        ppid = getppid();
        //kill(ppid, SIGTERM);
        /* Kill procress group */
        kill(-1 * pgid, SIGTERM);
        return 0;
    } else {
        /* Execute command specified starting with argv[2] */
        if (execvp(argv[2], &argv[2]) == -1) {
            perror("execvp");
            return -1;
        }
    }
    return 0;
}