1 files changed, 62 insertions, 0 deletions
diff --git a/init/builtins.c b/init/builtins.c
index b9b5029..303a8ca 100644
--- a/init/builtins.c
+++ b/init/builtins.c
@@ -205,6 +205,68 @@ int do_exec(int nargs, char **args)
     return -1;
 }
 
+int do_execonce(int nargs, char **args)
+{
+    pid_t child;
+    int child_status = 0;
+    static int already_done;
+
+    if (already_done) {
+      return -1;
+    }
+    already_done = 1;
+    if (!(child = fork())) {
+        /*
+         * Child process.
+         */
+        zap_stdio();
+        char *exec_args[100];
+        int i;
+        int num_process_args = nargs;
+
+        memset(exec_args, 0, sizeof(exec_args));
+        if (num_process_args > ARRAY_SIZE(exec_args) - 1) {
+            ERROR("exec called with %d args, limit is %d", num_process_args,
+                  ARRAY_SIZE(exec_args) - 1);
+            _exit(1);
+        }
+        for (i = 1; i < num_process_args; i++)
+            exec_args[i - 1] = args[i];
+
+        if (execv(exec_args[0], exec_args) == -1) {
+            ERROR("Failed to execv '%s' (%s)", exec_args[0], strerror(errno));
+            _exit(1);
+        }
+        ERROR("Returned from execv()!");
+        _exit(1);
+    }
+
+    /*
+     * Parent process.
+     */
+    if (child == -1) {
+        ERROR("Fork failed\n");
+        return -1;
+    }
+
+    if (TEMP_FAILURE_RETRY(waitpid(child, &child_status, 0)) == -1) {
+        ERROR("waitpid(): failed (%s)\n", strerror(errno));
+        return -1;
+    }
+
+    if (WIFSIGNALED(child_status)) {
+        INFO("Child exited due to signal %d\n", WTERMSIG(child_status));
+        return -1;
+    } else if (WIFEXITED(child_status)) {
+        INFO("Child exited normally (exit code %d)\n", WEXITSTATUS(child_status));
+        return WEXITSTATUS(child_status);
+    }
+
+    ERROR("Abnormal child process exit\n");
+
+    return -1;
+}
+
 int do_export(int nargs, char **args)
 {
     return add_environment(args[1], args[2]);