Remove utils::DeviceForMountPoint().

We only use it to get misc block device path, it can be replaced
with get_bootloader_message_blk_device(), and for writing bootloader
message, we can use update_bootloader_message() instead.

Also removed dependency on libfs_mgr since we are now using
libbootloader_message instead of using libfs_mgr directly.

Bug: None
Test: update_engine_unittests
Test: perform an OTA with powerwash
Change-Id: I80d0eea8e3ef6084820298cc0079da26fe1bfc63

hardware_android.cc

diff --git a/hardware_android.cc b/hardware_android.cc
index 9dd8bb6..a8a479d 100644
--- a/hardware_android.cc
+++ b/hardware_android.cc
@@ -16,22 +16,16 @@
 
 #include "update_engine/hardware_android.h"
 
-#include <fcntl.h>
-#include <sys/stat.h>
 #include <sys/types.h>
 
-#include <algorithm>
 #include <memory>
 
 #include <android-base/properties.h>
 #include <base/files/file_util.h>
-#include <base/strings/stringprintf.h>
 #include <bootloader_message/bootloader_message.h>
 
 #include "update_engine/common/hardware.h"
 #include "update_engine/common/platform_constants.h"
-#include "update_engine/common/utils.h"
-#include "update_engine/utils_android.h"
 
 using android::base::GetBoolProperty;
 using android::base::GetIntProperty;
@@ -42,12 +36,6 @@
 
 namespace {
 
-// The powerwash arguments passed to recovery. Arguments are separated by \n.
-const char kAndroidRecoveryPowerwashCommand[] =
-    "recovery\n"
-    "--wipe_data\n"
-    "--reason=wipe_data_from_ota\n";
-
 // Android properties that identify the hardware and potentially non-updatable
 // parts of the bootloader (such as the bootloader version and the baseband
 // version).
@@ -58,39 +46,6 @@
 const char kPropBootRevision[] = "ro.boot.revision";
 const char kPropBuildDateUTC[] = "ro.build.date.utc";
 
-// Write a recovery command line |message| to the BCB. The arguments to recovery
-// must be separated by '\n'. An empty string will erase the BCB.
-bool WriteBootloaderRecoveryMessage(const string& message) {
-  base::FilePath misc_device;
-  if (!utils::DeviceForMountPoint("/misc", &misc_device))
-    return false;
-
-  // Setup a bootloader_message with just the command and recovery fields set.
-  bootloader_message boot = {};
-  if (!message.empty()) {
-    strncpy(boot.command, "boot-recovery", sizeof(boot.command) - 1);
-    memcpy(boot.recovery,
-           message.data(),
-           std::min(message.size(), sizeof(boot.recovery) - 1));
-  }
-
-  int fd = HANDLE_EINTR(open(misc_device.value().c_str(), O_WRONLY | O_SYNC));
-  if (fd < 0) {
-    PLOG(ERROR) << "Opening misc";
-    return false;
-  }
-  ScopedFdCloser fd_closer(&fd);
-  // We only re-write the first part of the bootloader_message, up to and
-  // including the recovery message.
-  size_t boot_size =
-      offsetof(bootloader_message, recovery) + sizeof(boot.recovery);
-  if (!utils::WriteAll(fd, &boot, boot_size)) {
-    PLOG(ERROR) << "Writing recovery command to misc";
-    return false;
-  }
-  return true;
-}
-
 }  // namespace
 
 namespace hardware {
@@ -199,11 +154,22 @@
 
 bool HardwareAndroid::SchedulePowerwash() {
   LOG(INFO) << "Scheduling a powerwash to BCB.";
-  return WriteBootloaderRecoveryMessage(kAndroidRecoveryPowerwashCommand);
+  string err;
+  if (!update_bootloader_message({"--wipe_data", "--reason=wipe_data_from_ota"},
+                                 &err)) {
+    LOG(ERROR) << "Failed to update bootloader message: " << err;
+    return false;
+  }
+  return true;
 }
 
 bool HardwareAndroid::CancelPowerwash() {
-  return WriteBootloaderRecoveryMessage("");
+  string err;
+  if (!clear_bootloader_message(&err)) {
+    LOG(ERROR) << "Failed to clear bootloader message: " << err;
+    return false;
+  }
+  return true;
 }
 
 bool HardwareAndroid::GetNonVolatileDirectory(base::FilePath* path) const {