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Commit 88cc5f60 authored by Treehugger Robot's avatar Treehugger Robot Committed by Automerger Merge Worker
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Merge "Fix bug in WriteStringToFileAtomic" am: 862f8b15 

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2251734



Change-Id: I34e97fb316de84cc0cde71d497e902df66274729
Signed-off-by: default avatarAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
parents 0ad558c5 862f8b15

fs_mgr/libsnapshot/utility.cpp

+17 −3
Original line number Diff line number Diff line
@@ -153,10 +153,24 @@ AutoUnmountDevice::~AutoUnmountDevice() { 
}



bool WriteStringToFileAtomic(const std::string& content, const std::string& path) {

    std::string tmp_path = path + ".tmp";

    if (!android::base::WriteStringToFile(content, tmp_path)) {

    const std::string tmp_path = path + ".tmp";

    {

        const int flags = O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_BINARY;

        android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(tmp_path.c_str(), flags, 0666)));

        if (fd == -1) {

            PLOG(ERROR) << "Failed to open " << path;

            return false;

        }

        if (!android::base::WriteStringToFd(content, fd)) {

            PLOG(ERROR) << "Failed to write to fd " << fd;

            return false;

        }

        // rename() without fsync() is not safe. Data could still be living on page cache. To ensure

        // atomiticity, call fsync()

        if (fsync(fd) != 0) {

            PLOG(ERROR) << "Failed to fsync " << tmp_path;

        }

    }

    if (rename(tmp_path.c_str(), path.c_str()) == -1) {

        PLOG(ERROR) << "rename failed from " << tmp_path << " to " << path;

        return false;