90 lines
2.2 KiB
C
90 lines
2.2 KiB
C
#define _GNU_SOURCE
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <signal.h>
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#include <sys/prctl.h>
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#include <sys/wait.h>
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#include <errno.h>
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static volatile pid_t g_main_child = 0;
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static volatile sig_atomic_t g_child_exited = 0;
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static volatile int g_main_status = 0;
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static void sigchld_handler(int sig) {
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(void)sig;
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int status;
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pid_t pid;
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// Reap all terminated orphans
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while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
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if (pid == g_main_child) {
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g_child_exited = 1;
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g_main_status = status;
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}
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}
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}
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static void forward_signal(int sig) {
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if (g_main_child > 0) {
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kill(g_main_child, sig);
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}
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}
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int main(int argc, char *argv[]) {
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if (argc < 2) {
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fprintf(stderr, "Usage: %s <command> [args...]\n", argv[0]);
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return 1;
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}
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// Become a subreaper for any reparented processes down the tree
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if (prctl(PR_SET_CHILD_SUBREAPER, 1, 0, 0, 0) < 0) {
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perror("prctl(PR_SET_CHILD_SUBREAPER)");
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return 1;
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}
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// Set up signal forwarding
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struct sigaction sa_forward;
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sa_forward.sa_handler = forward_signal;
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sigemptyset(&sa_forward.sa_mask);
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sa_forward.sa_flags = SA_RESTART;
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sigaction(SIGTERM, &sa_forward, NULL);
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sigaction(SIGINT, &sa_forward, NULL);
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sigaction(SIGHUP, &sa_forward, NULL);
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// Set up SIGCHLD reaper handler
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struct sigaction sa_chld;
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sa_chld.sa_handler = sigchld_handler;
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sigemptyset(&sa_chld.sa_mask);
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sa_chld.sa_flags = SA_RESTART | SA_NOCLDSTOP;
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sigaction(SIGCHLD, &sa_chld, NULL);
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// Spawn the primary workload
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g_main_child = fork();
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if (g_main_child < 0) {
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perror("fork");
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return 1;
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}
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if (g_main_child == 0) {
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execvp(argv[1], &argv[1]);
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perror("execvp");
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_exit(127);
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}
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// Block until the primary process exits
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while (!g_child_exited) {
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pause();
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}
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// Final sweep of any remaining lingering zombies
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while (waitpid(-1, NULL, WNOHANG) > 0);
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if (WIFEXITED(g_main_status)) {
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return WEXITSTATUS(g_main_status);
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} else if (WIFSIGNALED(g_main_status)) {
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return 128 + WTERMSIG(g_main_status);
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}
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return 0;
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}
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