Re: [PATCH] repack.c: chmod +w before rename()

> commit a1bbc6c0 "repack: rewrite the shell script in C" introduced
> a possible regression, when a Git repo is located on a Windows network share.
> 
> When git gc is called on an already packed repository, it could fail like this:
> "fatal: renaming '.git/objects/pack/.tmp-xyz.pack' failed: Permission denied"
> 
> Temporary *.pack and *.idx files remain in .git/objects/pack/
> 
> In a1bbc6c0 the rename() function replaced the "mv -f" shell command.
> 
> Obviously the -f option can also override a read-only file but
> rename() can not on a network share.
> 
> Make the C-code to work similar to the shell script, by making the
> files writable before calling rename().
> 
> Another solution could be to do the "chmod +x" in mingw_rename().
> This may be done in another commit, because
> a) It improves git gc only when Git for Windows is used
>    on the client machine
> b) Windows refuses to delete a file when the file is read-only.
>    So setting a file to read-only under Windows is a way for a user
>    to protect it from being deleted.
>    Changing the behaviour of rename() globally may not be what we want.
> 
> Reported-by: Jochen Haag <zwanzig12@googlemail.com>
> Signed-off-by: Torsten Bögershausen <tboegi@web.de>
> ---
>  builtin/repack.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/builtin/repack.c b/builtin/repack.c
> index ba66c6e..033b4c2 100644
> --- a/builtin/repack.c
> +++ b/builtin/repack.c
> @@ -324,6 +324,10 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
>  				statbuffer.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
>  				chmod(fname_old, statbuffer.st_mode);
>  			}
> +			if (!stat(fname, &statbuffer)) {
> +				statbuffer.st_mode |= (S_IWUSR | S_IWGRP | S_IWOTH);
> +				chmod(fname, statbuffer.st_mode);
> +			}