[12/17] Move runas handling from vl.c to OS specific files.

diff --git a/os-posix.c b/os-posix.c
index 0deddf3..8b686a4 100644
--- a/os-posix.c
+++ b/os-posix.c
@@ -28,6 +28,7 @@ 
 #include <signal.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <pwd.h>
 #include <libgen.h>
 
 /* Needed early for CONFIG_BSD etc. */
@@ -36,6 +37,8 @@ 
 #include "net/slirp.h"
 #include "qemu-options.h"
 
+static struct passwd *user_pwd;
+
 void os_setup_early_signal_handling(void)
 {
     struct sigaction act;
@@ -146,6 +149,31 @@  void os_parse_cmd_args(int index, const char *optarg)
             exit(1);
         break;
 #endif
+    case QEMU_OPTION_runas:
+        user_pwd = getpwnam(optarg);
+        if (!user_pwd) {
+            fprintf(stderr, "User \"%s\" doesn't exist\n", optarg);
+            exit(1);
+        }
+        break;
     }
     return;
 }
+
+void os_change_process_uid(void)
+{
+    if (user_pwd) {
+        if (setgid(user_pwd->pw_gid) < 0) {
+            fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
+            exit(1);
+        }
+        if (setuid(user_pwd->pw_uid) < 0) {
+            fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
+            exit(1);
+        }
+        if (setuid(0) != -1) {
+            fprintf(stderr, "Dropping privileges failed\n");
+            exit(1);
+        }
+    }
+}
diff --git a/qemu-os-posix.h b/qemu-os-posix.h
index ff5adb1..6d8cf79 100644
--- a/qemu-os-posix.h
+++ b/qemu-os-posix.h
@@ -31,5 +31,6 @@  static inline void os_host_main_loop_wait(int *timeout)
 }
 
 void os_setup_signal_handling(void);
+void os_change_process_uid(void);
 
 #endif
diff --git a/qemu-os-win32.h b/qemu-os-win32.h
index e7e2ee3..70fdca5 100644
--- a/qemu-os-win32.h
+++ b/qemu-os-win32.h
@@ -43,5 +43,6 @@  void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque);
 void os_host_main_loop_wait(int *timeout);
 
 static inline void os_setup_signal_handling(void) {}
+static inline void os_change_process_uid(void) {}
 
 #endif
diff --git a/vl.c b/vl.c
index 7c48024..5fa4c79 100644
--- a/vl.c
+++ b/vl.c
@@ -34,7 +34,6 @@ 
 
 #ifndef _WIN32
 #include <libgen.h>
-#include <pwd.h>
 #include <sys/times.h>
 #include <sys/wait.h>
 #include <termios.h>
@@ -2310,9 +2309,7 @@  int main(int argc, char **argv, char **envp)
     const char *incoming = NULL;
 #ifndef _WIN32
     int fd = 0;
-    struct passwd *pwd = NULL;
     const char *chroot_dir = NULL;
-    const char *run_as = NULL;
 #endif
     int show_vnc_port = 0;
     int defconfig = 1;
@@ -3060,9 +3057,6 @@  int main(int argc, char **argv, char **envp)
             case QEMU_OPTION_chroot:
                 chroot_dir = optarg;
                 break;
-            case QEMU_OPTION_runas:
-                run_as = optarg;
-                break;
 #endif
             case QEMU_OPTION_xen_domid:
                 if (!(xen_available())) {
@@ -3552,14 +3546,6 @@  int main(int argc, char **argv, char **envp)
 	    exit(1);
     }
 
-    if (run_as) {
-        pwd = getpwnam(run_as);
-        if (!pwd) {
-            fprintf(stderr, "User \"%s\" doesn't exist\n", run_as);
-            exit(1);
-        }
-    }
-
     if (chroot_dir) {
         if (chroot(chroot_dir) < 0) {
             fprintf(stderr, "chroot failed\n");
@@ -3571,20 +3557,7 @@  int main(int argc, char **argv, char **envp)
         }
     }
 
-    if (run_as) {
-        if (setgid(pwd->pw_gid) < 0) {
-            fprintf(stderr, "Failed to setgid(%d)\n", pwd->pw_gid);
-            exit(1);
-        }
-        if (setuid(pwd->pw_uid) < 0) {
-            fprintf(stderr, "Failed to setuid(%d)\n", pwd->pw_uid);
-            exit(1);
-        }
-        if (setuid(0) != -1) {
-            fprintf(stderr, "Dropping privileges failed\n");
-            exit(1);
-        }
-    }
+    os_change_process_uid();
 
     if (daemonize) {
         dup2(fd, 0);