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Commit 97437a7a authored by Tom Cherry's avatar Tom Cherry
Browse files

init: fsync() persistent properties directory after rename() 

See the inline comment on why this is necessary.

Test: persistent properties work without errors
Change-Id: I820a193fb032a1845791a55a76390d396678f151
parent 1dd1056f

init/persistent_properties.cpp

+14 −1
Original line number Diff line number Diff line
@@ -31,10 +31,11 @@ 


#include "util.h"



using android::base::Dirname;

using android::base::ReadFdToString;

using android::base::StartsWith;

using android::base::WriteStringToFd;

using android::base::unique_fd;

using android::base::WriteStringToFd;



namespace android {

namespace init {
@@ -191,6 +192,18 @@ Result<void> WritePersistentPropertyFile(const PersistentProperties& persistent_ 
        unlink(temp_filename.c_str());

        return Error(saved_errno) << "Unable to rename persistent property file";

    }



    // rename() is atomic with regards to the kernel's filesystem buffers, but the parent

    // directories must be fsync()'ed otherwise, the rename is not necessarily written to storage.

    // Note in this case, that the source and destination directories are the same, so only one

    // fsync() is required.

    auto dir = Dirname(persistent_property_filename);

    auto dir_fd = unique_fd{open(dir.c_str(), O_DIRECTORY | O_RDONLY)};

    if (dir_fd < 0) {

        return ErrnoError() << "Unable to open persistent properties directory for fsync()";

    }

    fsync(dir_fd);



    return {};

}