tuxreaperd: split into libc and freestanding AMD64/ARM64 asm implementations for 0.3

tuxreaperdgnu.c

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