81 lines
1.5 KiB
C
81 lines
1.5 KiB
C
/*
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* dumb-init is a simple wrapper program designed to run as PID 1 and pass
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* signals to its children.
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*
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* Usage:
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* ./dumb-init python -c 'while True: pass'
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*
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* To get debug output on stderr, run with DUMB_INIT_DEBUG=1.
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*/
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <unistd.h>
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pid_t child = -1;
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char debug = 0;
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void signal_handler(int signum) {
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if (debug)
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fprintf(stderr, "Received signal %d.\n", signum);
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if (child > 0) {
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kill(child, signum);
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if (debug)
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fprintf(stderr, "Forwarded signal to child.\n");
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}
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}
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int main(int argc, char *argv[]) {
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int signum;
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char* debug_env;
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if (argc < 2) {
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fprintf(stderr, "Try providing some arguments.\n");
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return 1;
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}
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debug_env = getenv("DUMB_INIT_DEBUG");
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if (debug_env && strcmp(debug_env, "1") == 0)
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debug = 1;
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/* register signal handlers */
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for (signum = 1; signum < 32; signum++) {
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if (signum == SIGKILL || signum == SIGSTOP || signum == SIGCHLD)
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continue;
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if (signal(signum, signal_handler) == SIG_ERR) {
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fprintf(stderr, "Error: Couldn't register signal handler for signal `%d`. Exiting.\n", signum);
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return 1;
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}
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}
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/* launch our process */
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child = fork();
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if (child < 0) {
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fprintf(stderr, "Unable to fork. Exiting.\n");
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return 1;
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}
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if (child == 0) {
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execvp(argv[1], &argv[1]);
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} else {
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if (debug)
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fprintf(stderr, "Child spawned with PID %d.\n", child);
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waitpid(child, NULL, 0);
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if (debug)
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fprintf(stderr, "Child exited, goodbye.\n");
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}
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return 0;
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}
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