• Lars Schneider's avatar
    read-cache: make sure file handles are not inherited by child processes · a0a6cb96
    Lars Schneider authored
    This fixes "convert: add filter.<driver>.process option" (edcc8581) on
    Windows.
    
    Consider the case of a file that requires filtering and is present in
    branch A but not in branch B. If A is the current HEAD and we checkout B
    then the following happens:
    
    1. ce_compare_data() opens the file
    2.   index_fd() detects that the file requires to run a clean filter and
         calls index_stream_convert_blob()
    4.     index_stream_convert_blob() calls convert_to_git_filter_fd()
    5.       convert_to_git_filter_fd() calls apply_filter() which creates a
             new long running filter process (in case it is the first file
             of this kind to be filtered)
    6.       The new filter process inherits all file handles. This is the
             default on Linux/OSX and is explicitly defined in the
             `CreateProcessW` call in `mingw.c` on Windows.
    7. ce_compare_data() closes the file
    8. Git unlinks the file as it is not present in B
    
    The unlink operation does not work on Windows because the filter process
    has still an open handle to the file. On Linux/OSX the unlink operation
    succeeds but the file descriptors still leak into the child process.
    
    Fix this problem by opening files in read-cache with the O_CLOEXEC flag
    to ensure that the file descriptor does not remain open in a newly
    spawned process similar to 05d1ed61 ("mingw: ensure temporary file
    handles are not inherited by child processes", 2016-08-22).
    Signed-off-by: default avatarLars Schneider <larsxschneider@gmail.com>
    Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
    a0a6cb96
read-cache.c 62.5 KB