Merge "adb: use /system/bin/remount command" am: d458066bc7
am: bc0887add7

Change-Id: I3f6725ac4cbb181210f1f91b159cd31674f1b690
diff --git a/adb/Android.bp b/adb/Android.bp
index 3813578..1e085a7 100644
--- a/adb/Android.bp
+++ b/adb/Android.bp
@@ -402,6 +402,14 @@
         "liblog",
     ],
 
+    product_variables: {
+        debuggable: {
+            required: [
+                "remount",
+            ],
+        },
+    },
+
     target: {
         android: {
             srcs: [
diff --git a/adb/daemon/remount_service.cpp b/adb/daemon/remount_service.cpp
index 5e6d416..7999ddc 100644
--- a/adb/daemon/remount_service.cpp
+++ b/adb/daemon/remount_service.cpp
@@ -14,339 +14,81 @@
  * limitations under the License.
  */
 
-#define TRACE_TAG ADB
-
-#include "sysdeps.h"
-
 #include <errno.h>
 #include <fcntl.h>
-#include <mntent.h>
-#include <spawn.h>
-#include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
-#include <sys/mount.h>
-#include <sys/statvfs.h>
-#include <sys/vfs.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 #include <unistd.h>
 
-#include <memory>
-#include <set>
 #include <string>
-#include <vector>
-
-#include <android-base/file.h>
-#include <android-base/properties.h>
-#include <bootloader_message/bootloader_message.h>
-#include <cutils/android_reboot.h>
-#include <fs_mgr.h>
-#include <fs_mgr_overlayfs.h>
 
 #include "adb.h"
 #include "adb_io.h"
 #include "adb_unique_fd.h"
-#include "adb_utils.h"
-#include "set_verity_enable_state_service.h"
-
-using android::base::Realpath;
-using android::fs_mgr::Fstab;
-using android::fs_mgr::ReadDefaultFstab;
-
-// Returns the last device used to mount a directory in /proc/mounts.
-// This will find overlayfs entry where upperdir=lowerdir, to make sure
-// remount is associated with the correct directory.
-static std::string find_proc_mount(const char* dir) {
-    std::unique_ptr<FILE, int(*)(FILE*)> fp(setmntent("/proc/mounts", "r"), endmntent);
-    std::string mnt_fsname;
-    if (!fp) return mnt_fsname;
-
-    // dir might be a symlink, e.g., /product -> /system/product in GSI.
-    std::string canonical_path;
-    if (!Realpath(dir, &canonical_path)) {
-        PLOG(ERROR) << "Realpath failed: " << dir;
-    }
-
-    mntent* e;
-    while ((e = getmntent(fp.get())) != nullptr) {
-        if (canonical_path == e->mnt_dir) {
-            mnt_fsname = e->mnt_fsname;
-        }
-    }
-    return mnt_fsname;
-}
-
-// Returns the device used to mount a directory in the fstab.
-static std::string find_fstab_mount(const char* dir) {
-    Fstab fstab;
-    if (!ReadDefaultFstab(&fstab)) {
-        return "";
-    }
-
-    auto entry = std::find_if(fstab.begin(), fstab.end(),
-                              [&dir](const auto& entry) { return entry.mount_point == dir; });
-    if (entry == fstab.end()) {
-        return "";
-    }
-    if (entry->fs_mgr_flags.logical) {
-        fs_mgr_update_logical_partition(&(*entry));
-    }
-    return entry->blk_device;
-}
-
-// The proc entry for / is full of lies, so check fstab instead.
-// /proc/mounts lists rootfs and /dev/root, neither of which is what we want.
-static std::string find_mount(const char* dir, bool is_root) {
-    if (is_root) {
-        return find_fstab_mount(dir);
-    } else {
-        return find_proc_mount(dir);
-    }
-}
-
-bool dev_is_overlayfs(const std::string& dev) {
-    return (dev == "overlay") || (dev == "overlayfs");
-}
-
-bool make_block_device_writable(const std::string& dev) {
-    if (dev_is_overlayfs(dev)) return true;
-    int fd = unix_open(dev, O_RDONLY | O_CLOEXEC);
-    if (fd == -1) {
-        return false;
-    }
-
-    int OFF = 0;
-    bool result = (ioctl(fd, BLKROSET, &OFF) != -1);
-    unix_close(fd);
-    return result;
-}
-
-static bool can_unshare_blocks(int fd, const char* dev) {
-    const char* E2FSCK_BIN = "/system/bin/e2fsck";
-    if (access(E2FSCK_BIN, X_OK)) {
-        WriteFdFmt(fd, "e2fsck is not available, cannot undo deduplication on %s\n", dev);
-        return false;
-    }
-
-    pid_t child;
-    char* env[] = {nullptr};
-    const char* argv[] = {E2FSCK_BIN, "-n", "-E", "unshare_blocks", dev, nullptr};
-    if (posix_spawn(&child, E2FSCK_BIN, nullptr, nullptr, const_cast<char**>(argv), env)) {
-        WriteFdFmt(fd, "failed to e2fsck to check deduplication: %s\n", strerror(errno));
-        return false;
-    }
-    int status = 0;
-    int ret = TEMP_FAILURE_RETRY(waitpid(child, &status, 0));
-    if (ret < 0) {
-        WriteFdFmt(fd, "failed to get e2fsck status: %s\n", strerror(errno));
-        return false;
-    }
-    if (!WIFEXITED(status)) {
-        WriteFdFmt(fd, "e2fsck exited abnormally with status %d\n", status);
-        return false;
-    }
-    int rc = WEXITSTATUS(status);
-    if (rc != 0) {
-        WriteFdFmt(fd,
-                   "%s is deduplicated, and an e2fsck check failed. It might not "
-                   "have enough free-space to be remounted as writable.\n",
-                   dev);
-        return false;
-    }
-    return true;
-}
-
-static unsigned long get_mount_flags(int fd, const char* dir) {
-    struct statvfs st_vfs;
-    if (statvfs(dir, &st_vfs) == -1) {
-        // Even though we could not get the original mount flags, assume that
-        // the mount was originally read-only.
-        WriteFdFmt(fd, "statvfs of the %s mount failed: %s.\n", dir, strerror(errno));
-        return MS_RDONLY;
-    }
-    return st_vfs.f_flag;
-}
-
-static bool remount_partition(int fd, const char* dir) {
-    if (!directory_exists(dir)) {
-        return true;
-    }
-    bool is_root = strcmp(dir, "/") == 0;
-    if (is_root && dev_is_overlayfs(find_mount("/system", false))) {
-        dir = "/system";
-        is_root = false;
-    }
-    std::string dev = find_mount(dir, is_root);
-    if (is_root && dev.empty()) {
-        // The fstab entry will be /system if the device switched roots during
-        // first-stage init.
-        dev = find_mount("/system", true);
-    }
-    // Even if the device for the root is not found, we still try to remount it
-    // as rw. This typically only happens when running Android in a container:
-    // the root will almost always be in a loop device, which is dynamic, so
-    // it's not convenient to put in the fstab.
-    if (dev.empty() && !is_root) {
-        return true;
-    }
-    if (!dev.empty() && !make_block_device_writable(dev)) {
-        WriteFdFmt(fd, "remount of %s failed; couldn't make block device %s writable: %s\n",
-                   dir, dev.c_str(), strerror(errno));
-        return false;
-    }
-
-    unsigned long remount_flags = get_mount_flags(fd, dir);
-    remount_flags &= ~MS_RDONLY;
-    remount_flags |= MS_REMOUNT;
-
-    if (mount(dev.c_str(), dir, "none", remount_flags | MS_BIND, nullptr) == -1) {
-        // This is useful for cases where the superblock is already marked as
-        // read-write, but the mount itself is read-only, such as containers
-        // where the remount with just MS_REMOUNT is forbidden by the kernel.
-        WriteFdFmt(fd, "remount of the %s mount failed: %s.\n", dir, strerror(errno));
-        return false;
-    }
-    if (mount(dev.c_str(), dir, "none", MS_REMOUNT, nullptr) == -1) {
-        WriteFdFmt(fd, "remount of the %s superblock failed: %s\n", dir, strerror(errno));
-        return false;
-    }
-    return true;
-}
-
-static void reboot_for_remount(int fd, bool need_fsck) {
-    std::string reboot_cmd = "reboot";
-    if (need_fsck) {
-        const std::vector<std::string> options = {"--fsck_unshare_blocks"};
-        std::string err;
-        if (!write_bootloader_message(options, &err)) {
-            WriteFdFmt(fd, "Failed to set bootloader message: %s\n", err.c_str());
-            return;
-        }
-
-        WriteFdExactly(fd,
-                       "The device will now reboot to recovery and attempt "
-                       "un-deduplication.\n");
-        reboot_cmd = "reboot,recovery";
-    }
-
-    sync();
-    android::base::SetProperty(ANDROID_RB_PROPERTY, reboot_cmd.c_str());
-}
-
-static void try_unmount_bionic(int fd) {
-    static constexpr const char* kBionic = "/bionic";
-    struct statfs buf;
-    if (statfs(kBionic, &buf) == -1) {
-        WriteFdFmt(fd, "statfs of the %s mount failed: %s.\n", kBionic, strerror(errno));
-        return;
-    }
-    if (buf.f_flags & ST_RDONLY) {
-        // /bionic is on a read-only partition; can happen for
-        // non-system-as-root-devices. Don' try to unmount.
-        return;
-    }
-    // Success/Fail of the actual remount will be reported by the function.
-    remount_partition(fd, kBionic);
-    return;
-}
 
 void remount_service(unique_fd fd, const std::string& cmd) {
-    bool user_requested_reboot = cmd == "-R";
+    static constexpr char remount_cmd[] = "/system/bin/remount";
+    static constexpr char remount_failed[] = "remount failed\n";
 
     if (getuid() != 0) {
         WriteFdExactly(fd.get(), "Not running as root. Try \"adb root\" first.\n");
+        WriteFdExactly(fd.get(), remount_failed);
         return;
     }
 
-    bool system_verified = !(android::base::GetProperty("partition.system.verified", "").empty());
-    bool vendor_verified = !(android::base::GetProperty("partition.vendor.verified", "").empty());
-
-    std::vector<std::string> partitions{"/",        "/odm",   "/oem", "/product_services",
-                                        "/product", "/vendor"};
-
-    if (system_verified || vendor_verified) {
-        // Disable verity automatically (reboot will be required).
-        set_verity_enabled_state_service(unique_fd(dup(fd.get())), false);
-
-        // If overlayfs is not supported, we try and remount or set up
-        // un-deduplication. If it is supported, we can go ahead and wait for
-        // a reboot.
-        if (fs_mgr_overlayfs_valid() != OverlayfsValidResult::kNotSupported) {
-            if (user_requested_reboot) {
-                if (android::base::SetProperty(ANDROID_RB_PROPERTY, "reboot")) {
-                    WriteFdExactly(fd.get(), "rebooting device\n");
-                } else {
-                    WriteFdExactly(fd.get(), "reboot failed\n");
-                }
-            }
-            return;
-        }
-    } else if (fs_mgr_overlayfs_setup()) {
-        // If we can use overlayfs, lets get it in place first before we
-        // struggle with determining deduplication operations.
-        Fstab fstab;
-        if (ReadDefaultFstab(&fstab) && fs_mgr_overlayfs_mount_all(&fstab)) {
-            WriteFdExactly(fd.get(), "overlayfs mounted\n");
-        }
-    }
-
-    // If overlayfs is supported, we don't bother trying to un-deduplicate
-    // partitions.
-    std::set<std::string> dedup;
-    if (fs_mgr_overlayfs_valid() == OverlayfsValidResult::kNotSupported) {
-        // Find partitions that are deduplicated, and can be un-deduplicated.
-        for (const auto& part : partitions) {
-            auto partition = part;
-            if ((part == "/") && !find_mount("/system", false).empty()) partition = "/system";
-            std::string dev = find_mount(partition.c_str(), partition == "/");
-            if (dev.empty() || !fs_mgr_has_shared_blocks(partition, dev)) {
-                continue;
-            }
-            if (can_unshare_blocks(fd.get(), dev.c_str())) {
-                dedup.emplace(partition);
-            }
-        }
-
-        // Reboot now if the user requested it (and an operation needs a reboot).
-        if (user_requested_reboot) {
-            if (!dedup.empty()) {
-                reboot_for_remount(fd.get(), !dedup.empty());
-                return;
-            }
-            WriteFdExactly(fd.get(), "No reboot needed, skipping -R.\n");
-        }
-    }
-
-    bool success = true;
-    for (const auto& partition : partitions) {
-        // Don't try to remount partitions that need an fsck in recovery.
-        if (dedup.count(partition)) {
-            continue;
-        }
-        success &= remount_partition(fd.get(), partition.c_str());
-    }
-
-    if (!dedup.empty()) {
-        WriteFdExactly(fd.get(),
-                       "The following partitions are deduplicated and cannot "
-                       "yet be remounted:\n");
-        for (const std::string& name : dedup) {
-            WriteFdFmt(fd.get(), "  %s\n", name.c_str());
-        }
-
-        WriteFdExactly(fd.get(),
-                       "To reboot and un-deduplicate the listed partitions, "
-                       "please retry with adb remount -R.\n");
-        if (system_verified || vendor_verified) {
-            WriteFdExactly(fd.get(), "Note: verity will be automatically disabled after reboot.\n");
-        }
+    auto pid = vfork();
+    if (pid < 0) {
+        WriteFdFmt(fd.get(), "Failed to fork to %s: %s\n", remount_cmd, strerror(errno));
+        WriteFdExactly(fd.get(), remount_failed);
         return;
     }
 
-    try_unmount_bionic(fd.get());
+    if (pid == 0) {
+        // child side of the fork
+        fcntl(fd.get(), F_SETFD, 0);
+        dup2(fd.get(), STDIN_FILENO);
+        dup2(fd.get(), STDOUT_FILENO);
+        dup2(fd.get(), STDERR_FILENO);
 
-    if (!success) {
-        WriteFdExactly(fd.get(), "remount failed\n");
-    } else {
-        WriteFdExactly(fd.get(), "remount succeeded\n");
+        execl(remount_cmd, remount_cmd, cmd.empty() ? nullptr : cmd.c_str(), nullptr);
+        _exit(-errno ?: 42);
     }
+
+    int wstatus = 0;
+    auto ret = waitpid(pid, &wstatus, 0);
+
+    if (ret == -1) {
+        WriteFdFmt(fd.get(), "Failed to wait for %s: %s\n", remount_cmd, strerror(errno));
+        goto err;
+    }
+
+    if (ret != pid) {
+        WriteFdFmt(fd.get(), "pid %d and waitpid return %d do not match for %s\n",
+                   static_cast<int>(pid), static_cast<int>(ret), remount_cmd);
+        goto err;
+    }
+
+    if (WIFSIGNALED(wstatus)) {
+        WriteFdFmt(fd.get(), "%s terminated with signal %s\n", remount_cmd,
+                   strsignal(WTERMSIG(wstatus)));
+        goto err;
+    }
+
+    if (!WIFEXITED(wstatus)) {
+        WriteFdFmt(fd.get(), "%s stopped with status 0x%x\n", remount_cmd, wstatus);
+        goto err;
+    }
+
+    if (WEXITSTATUS(wstatus)) {
+        WriteFdFmt(fd.get(), "%s exited with status %d\n", remount_cmd,
+                   static_cast<signed char>(WEXITSTATUS(wstatus)));
+        goto err;
+    }
+
+    WriteFdExactly(fd.get(), "remount succeeded\n");
+    return;
+
+err:
+    WriteFdExactly(fd.get(), remount_failed);
 }
diff --git a/adb/daemon/remount_service.h b/adb/daemon/remount_service.h
index c847403..522a5da 100644
--- a/adb/daemon/remount_service.h
+++ b/adb/daemon/remount_service.h
@@ -21,6 +21,5 @@
 #include "adb_unique_fd.h"
 
 #if defined(__ANDROID__)
-bool make_block_device_writable(const std::string&);
 void remount_service(unique_fd, const std::string&);
 #endif
diff --git a/adb/daemon/set_verity_enable_state_service.cpp b/adb/daemon/set_verity_enable_state_service.cpp
index 92851c0..658261e 100644
--- a/adb/daemon/set_verity_enable_state_service.cpp
+++ b/adb/daemon/set_verity_enable_state_service.cpp
@@ -25,6 +25,7 @@
 #include <libavb_user/libavb_user.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <sys/mount.h>
 #include <sys/stat.h>
 
 #include <android-base/properties.h>
@@ -37,7 +38,6 @@
 #include "adb.h"
 #include "adb_io.h"
 #include "adb_unique_fd.h"
-#include "remount_service.h"
 
 #include "fec/io.h"
 
@@ -51,6 +51,18 @@
     if (getuid() != 0) WriteFdExactly(fd, "Maybe run adb root?\n");
 }
 
+static bool make_block_device_writable(const std::string& dev) {
+    int fd = unix_open(dev, O_RDONLY | O_CLOEXEC);
+    if (fd == -1) {
+        return false;
+    }
+
+    int OFF = 0;
+    bool result = (ioctl(fd, BLKROSET, &OFF) != -1);
+    unix_close(fd);
+    return result;
+}
+
 /* Turn verity on/off */
 static bool set_verity_enabled_state(int fd, const char* block_device, const char* mount_point,
                                      bool enable) {