init: chroot from recovery to /first_stage_ramdisk
When using the recovery image as a trampoline to boot the system,
first chroot from the recovery image to /first_stage_ramdisk, to
minimize differences between these two boot paths.
Primary motivation is due to the fact that the basename of each mount
point is used by device-manager to name its nodes, and the previous
code that created used /system_recovery_mount as the mount point for
system.img broke AVB. Instead of hacking around that issue, this
change unified mounting for the recovery trampoline and true first
stage ramdisk paths.
Bug: 114062208
Test: AVB works with blueline_mainline
Change-Id: Iffb154962b6e160150917e068f1e7d0bf7cb84e7
diff --git a/init/switch_root.cpp b/init/switch_root.cpp
index 0e59b57..cc75f31 100644
--- a/init/switch_root.cpp
+++ b/init/switch_root.cpp
@@ -16,7 +16,6 @@
#include "switch_root.h"
-#include <dirent.h>
#include <fcntl.h>
#include <mntent.h>
#include <sys/mount.h>
@@ -35,45 +34,6 @@
namespace {
-void FreeRamdisk(DIR* dir, dev_t dev) {
- int dfd = dirfd(dir);
-
- dirent* de;
- while ((de = readdir(dir)) != nullptr) {
- if (de->d_name == "."s || de->d_name == ".."s) {
- continue;
- }
-
- bool is_dir = false;
-
- if (de->d_type == DT_DIR || de->d_type == DT_UNKNOWN) {
- struct stat info;
- if (fstatat(dfd, de->d_name, &info, AT_SYMLINK_NOFOLLOW) != 0) {
- continue;
- }
-
- if (info.st_dev != dev) {
- continue;
- }
-
- if (S_ISDIR(info.st_mode)) {
- is_dir = true;
- auto fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
- if (fd >= 0) {
- auto subdir =
- std::unique_ptr<DIR, decltype(&closedir)>{fdopendir(fd), closedir};
- if (subdir) {
- FreeRamdisk(subdir.get(), dev);
- } else {
- close(fd);
- }
- }
- }
- }
- unlinkat(dfd, de->d_name, is_dir ? AT_REMOVEDIR : 0);
- }
-}
-
std::vector<std::string> GetMounts(const std::string& new_root) {
auto fp = std::unique_ptr<std::FILE, decltype(&endmntent)>{setmntent("/proc/mounts", "re"),
endmntent};
@@ -109,42 +69,32 @@
} // namespace
-void SwitchRoot(const std::string& new_root) {
+void SwitchRoot(const std::string& new_root, bool move_root_mount) {
auto mounts = GetMounts(new_root);
+ LOG(INFO) << "Switching root to '" << new_root << "'";
+
for (const auto& mount_path : mounts) {
auto new_mount_path = new_root + mount_path;
+ mkdir(new_mount_path.c_str(), 0755);
if (mount(mount_path.c_str(), new_mount_path.c_str(), nullptr, MS_MOVE, nullptr) != 0) {
PLOG(FATAL) << "Unable to move mount at '" << mount_path << "'";
}
}
- auto old_root_dir = std::unique_ptr<DIR, decltype(&closedir)>{opendir("/"), closedir};
- if (!old_root_dir) {
- PLOG(ERROR) << "Could not opendir(\"/\"), not freeing ramdisk";
- }
-
- struct stat old_root_info;
- if (stat("/", &old_root_info) != 0) {
- PLOG(ERROR) << "Could not stat(\"/\"), not freeing ramdisk";
- old_root_dir.reset();
- }
-
if (chdir(new_root.c_str()) != 0) {
PLOG(FATAL) << "Could not chdir to new_root, '" << new_root << "'";
}
- if (mount(new_root.c_str(), "/", nullptr, MS_MOVE, nullptr) != 0) {
- PLOG(FATAL) << "Unable to move root mount to new_root, '" << new_root << "'";
+ if (move_root_mount) {
+ if (mount(new_root.c_str(), "/", nullptr, MS_MOVE, nullptr) != 0) {
+ PLOG(FATAL) << "Unable to move root mount to new_root, '" << new_root << "'";
+ }
}
if (chroot(".") != 0) {
PLOG(FATAL) << "Unable to chroot to new root";
}
-
- if (old_root_dir) {
- FreeRamdisk(old_root_dir.get(), old_root_info.st_dev);
- }
}
} // namespace init