Move runas handling from vl.c to OS specific files.

Move code to handle runas, ie. change of user id of QEMU process
to OS specific files and provide dummy stub for Win32.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Acked-by: Juan Quintela <quintela@redhat.com>
Acked-by: Richard Henderson <rth@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

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);
+        }
+    }
+}

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

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

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())) {
@@ -3554,14 +3548,6 @@ 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");
@@ -3573,20 +3559,7 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
-    if (run_as) {
+    os_change_process_uid();
-        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);
-        }
-    }
 
     if (daemonize) {
         dup2(fd, 0);