Merge "adb: warn on remount if undoing deduplication is impossible"

#include <errno.h>

#include <fcntl.h>

#include <mntent.h>

#include <spawn.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

    return (info.feat_ro_compat & EXT4_FEATURE_RO_COMPAT_SHARED_BLOCKS) != 0;

}

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 bool remount_partition(int fd, const char* dir, std::vector<std::string>& dedup) {

    if (!directory_exists(dir)) {

        return true;

    }

    if (mount(dev.c_str(), dir, "none", MS_REMOUNT, nullptr) == -1) {

        if (errno == EROFS && fs_has_shared_blocks(dev.c_str())) {

            if (!can_unshare_blocks(fd, dev.c_str())) {

                return false;

            }

            // We return true so remount_service() can detect that the only

            // failure was deduplicated filesystems.

            dedup.push_back(dev);