Revert "Revert "adb: support /oem partition""

This reverts commit 6084a0124f868c7ec43f6c415a27a168f27ff694.

The original build breakage is fixed by (a) building the verity
code for eng builds as well as userdebug builds and (b) moving
the exported remount service functions into a new header file.

Change-Id: Ice0c4f97d4db38ab7eb333c7a6e56bbd11123f5b

1 files changed, 45 insertions, 64 deletions

diff --git a/adb/remount_service.cpp b/adb/remount_service.cpp
index 414b316..a83d5b1 100644
--- a/adb/remount_service.cpp
+++ b/adb/remount_service.cpp
@@ -23,6 +23,8 @@
 #include <sys/mount.h>
 #include <unistd.h>
 
+#include <string>
+
 #include "sysdeps.h"
 
 #define  TRACE_TAG  TRACE_ADB
@@ -32,10 +34,10 @@
 
 static int system_ro = 1;
 static int vendor_ro = 1;
+static int oem_ro = 1;
 
 /* Returns the device used to mount a directory in /proc/mounts */
-static char *find_mount(const char *dir)
-{
+static std::string find_mount(const char *dir) {
     FILE* fp;
     struct mntent* mentry;
     char* device = NULL;
@@ -45,7 +47,7 @@ static char *find_mount(const char *dir)
     }
     while ((mentry = getmntent(fp)) != NULL) {
         if (strcmp(dir, mentry->mnt_dir) == 0) {
-            device = strdup(mentry->mnt_fsname);
+            device = mentry->mnt_fsname;
             break;
         }
     }
@@ -53,64 +55,53 @@ static char *find_mount(const char *dir)
     return device;
 }
 
-static int hasVendorPartition()
-{
-    struct stat info;
-    if (!lstat("/vendor", &info))
-        if ((info.st_mode & S_IFMT) == S_IFDIR)
-          return true;
-    return false;
+static bool has_partition(const char* path) {
+    struct stat sb;
+    return (lstat(path, &sb) == 0 && S_ISDIR(sb.st_mode));
 }
 
-int make_block_device_writable(const char* dev)
-{
-    int fd = -1;
-    int OFF = 0;
-    int rc = -1;
-
-    if (!dev)
-        goto errout;
-
-    fd = unix_open(dev, O_RDONLY | O_CLOEXEC);
-    if (fd < 0)
-        goto errout;
-
-    if (ioctl(fd, BLKROSET, &OFF)) {
-        goto errout;
+int make_block_device_writable(const std::string& dev) {
+    int fd = unix_open(dev.c_str(), O_RDONLY | O_CLOEXEC);
+    if (fd == -1) {
+        return -1;
     }
 
-    rc = 0;
-
-errout:
-    if (fd >= 0) {
-        adb_close(fd);
+    int result = -1;
+    int OFF = 0;
+    if (!ioctl(fd, BLKROSET, &OFF)) {
+        result = 0;
     }
-    return rc;
-}
-
-/* Init mounts /system as read only, remount to enable writes. */
-static int remount(const char* dir, int* dir_ro)
-{
-    char *dev = 0;
-    int rc = -1;
+    adb_close(fd);
 
-    dev = find_mount(dir);
+    return result;
+}
 
-    if (!dev || make_block_device_writable(dev)) {
-        goto errout;
+// Init mounts /system as read only, remount to enable writes.
+static int remount(const char* dir, int* dir_ro) {
+    std::string dev(find_mount(dir));
+    if (dev.empty() || make_block_device_writable(dev)) {
+        return -1;
     }
 
-    rc = mount(dev, dir, "none", MS_REMOUNT, NULL);
+    int rc = mount(dev.c_str(), dir, "none", MS_REMOUNT, NULL);
     *dir_ro = rc;
-
-errout:
-    free(dev);
     return rc;
 }
 
-void remount_service(int fd, void *cookie)
-{
-    char buffer[200];
+static bool remount_partition(int fd, const char* partition, int* ro) {
+  if (!has_partition(partition)) {
+    return true;
+  }
+  if (remount(partition, ro)) {
+    char buf[200];
+    snprintf(buf, sizeof(buf), "remount of %s failed: %s\n", partition, strerror(errno));
+    WriteStringFully(fd, buf);
+    return false;
+  }
+  return true;
+}
+
+void remount_service(int fd, void* cookie) {
     char prop_buf[PROPERTY_VALUE_MAX];
 
     if (getuid() != 0) {
@@ -133,6 +124,7 @@ void remount_service(int fd, void *cookie)
     if (system_verified || vendor_verified) {
         // Allow remount but warn of likely bad effects
         bool both = system_verified && vendor_verified;
+        char buffer[200];
         snprintf(buffer, sizeof(buffer),
                  "dm_verity is enabled on the %s%s%s partition%s.\n",
                  system_verified ? "system" : "",
@@ -147,23 +139,12 @@ void remount_service(int fd, void *cookie)
         WriteStringFully(fd, buffer);
     }
 
-    if (remount("/system", &system_ro)) {
-        snprintf(buffer, sizeof(buffer), "remount of system failed: %s\n",strerror(errno));
-        WriteStringFully(fd, buffer);
-    }
-
-    if (hasVendorPartition()) {
-        if (remount("/vendor", &vendor_ro)) {
-            snprintf(buffer, sizeof(buffer), "remount of vendor failed: %s\n",strerror(errno));
-            WriteStringFully(fd, buffer);
-        }
-    }
+    bool success = true;
+    success &= remount_partition(fd, "/system", &system_ro);
+    success &= remount_partition(fd, "/vendor", &vendor_ro);
+    success &= remount_partition(fd, "/oem", &oem_ro);
 
-    if (!system_ro && (!vendor_ro || !hasVendorPartition()))
-        WriteStringFully(fd, "remount succeeded\n");
-    else {
-        WriteStringFully(fd, "remount failed\n");
-    }
+    WriteStringFully(fd, success ? "remount succeeded\n" : "remount failed\n");
 
     adb_close(fd);
 }