Try to unmount writable filesystems when rebooting

Ext4 filesystems like to be unmounted before rebooting.  The Android system
doesn't have a traditional Linux init setup, and shutting down the system
was not much more than calling sync(2) and reboot(2).  This adds a new
function to libcutils called android_reboot().  By default, it calls sync()
and then remounts all writable filesystems as read-only and marks them clean.
There is a flag parameter in which the caller can ask for sync() not to be
called, or to not remount the filesystems as read-only.  Then it will call
reboot(2) as directed by the other parameters.  This change also updates
adb, init and toolbox to call the new android_reboot() function.
Fixes bugs 3350709 and 3495575.

Change-Id: I16d71ffce3134310d7a260f61ec6f4dd204124a7

2 files changed, 10 insertions, 8 deletions

diff --git a/toolbox/reboot.c b/toolbox/reboot.c
index aebe18501..f8546de2d 100644
--- a/toolbox/reboot.c
+++ b/toolbox/reboot.c
@@ -1,7 +1,7 @@
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <sys/reboot.h>
+#include <cutils/android_reboot.h>
 #include <unistd.h>
 
 int reboot_main(int argc, char *argv[])
@@ -9,6 +9,7 @@ int reboot_main(int argc, char *argv[])
     int ret;
     int nosync = 0;
     int poweroff = 0;
+    int flags = 0;
 
     opterr = 0;
     do {
@@ -38,15 +39,16 @@ int reboot_main(int argc, char *argv[])
         exit(EXIT_FAILURE);
     }
 
-    if(!nosync)
-        sync();
+    if(nosync)
+        /* also set NO_REMOUNT_RO as remount ro includes an implicit sync */
+        flags = ANDROID_RB_FLAG_NO_SYNC | ANDROID_RB_FLAG_NO_REMOUNT_RO;
 
     if(poweroff)
-        ret = __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_POWER_OFF, NULL);
+        ret = android_reboot(ANDROID_RB_POWEROFF, flags, 0);
     else if(argc > optind)
-        ret = __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_RESTART2, argv[optind]);
+        ret = android_reboot(ANDROID_RB_RESTART2, flags, argv[optind]);
     else
-        ret = reboot(RB_AUTOBOOT);
+        ret = android_reboot(ANDROID_RB_RESTART, flags, 0);
     if(ret < 0) {
         perror("reboot");
         exit(EXIT_FAILURE);
diff --git a/toolbox/wipe.c b/toolbox/wipe.c
index 7e263fd44..650a0d664 100644
--- a/toolbox/wipe.c
+++ b/toolbox/wipe.c
@@ -5,7 +5,7 @@
 #include <string.h>
 #include <errno.h>
 #include <sys/types.h>
-#include <sys/reboot.h>
+#include <cutils/android_reboot.h>
 #include <sys/stat.h>
 
 #ifndef PATH_MAX
@@ -63,7 +63,7 @@ int wipe_main (int argc, char *argv[])
 		wipe ("/system");
         wipe ("/data");
 		fprintf(stdout, "Device nuked! Rebooting...\n");
-		ret = reboot(RB_AUTOBOOT);
+		ret = android_reboot(ANDROID_RB_RESTART, 0, 0);
 	    if (ret < 0) {
 	        fprintf(stderr, "Reboot failed, %s\n", strerror(errno));
 	        return 1;