Add support for NoMMU

Author: echelonxray

Makefile

@@ -1,5 +1,5 @@
 SHELL=bash
-CFLAGS=-std=gnu99 -static -s -Wall -Werror -O3
+CFLAGS_AUTO=-std=gnu99 -static-pie -s -Wall -Werror -O3
 
 TEST_PACKAGE_DEPS := build-essential python python-pip procps python-dev python-setuptools
 
@@ -8,7 +8,7 @@ VERSION = $(shell cat VERSION)
 
 .PHONY: build
 build: VERSION.h
-	$(CC) $(CFLAGS) -o dumb-init dumb-init.c
+	$(CC) $(CFLAGS_AUTO) $(CFLAGS) -o dumb-init dumb-init.c
 
 VERSION.h: VERSION
 	echo '// THIS FILE IS AUTOMATICALLY GENERATED' > VERSION.h

dumb-init.c

@@ -15,6 +15,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <spawn.h>
 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <sys/wait.h>
@@ -292,9 +293,9 @@ int main(int argc, char *argv[]) {
         }
     }
 
-    child_pid = fork();
+    child_pid = vfork();
     if (child_pid < 0) {
-        PRINTERR("Unable to fork. Exiting.\n");
+        PRINTERR("Unable to vfork. Exiting.\n");
         return 1;
     } else if (child_pid == 0) {
         /* child */
@@ -306,7 +307,7 @@ int main(int argc, char *argv[]) {
                     errno,
                     strerror(errno)
                 );
-                exit(1);
+                _exit(1);
             }
 
             if (ioctl(STDIN_FILENO, TIOCSCTTY, 0) == -1) {
@@ -322,7 +323,7 @@ int main(int argc, char *argv[]) {
 
         // if this point is reached, exec failed, so we should exit nonzero
         PRINTERR("%s: %s\n", cmd[0], strerror(errno));
-        return 2;
+        _exit(2);
     } else {
         /* parent */
         DEBUG("Child spawned with PID %d.\n", child_pid);
@@ -337,4 +338,6 @@ int main(int argc, char *argv[]) {
             handle_signal(signum);
         }
     }
+
+    return 1;
 }