Re: [PATCH] git_open_noatime: return with errno=0 on success

> In read_sha1_file_extended we die if read_object fails with a fatal
> error. We detect a fatal error if errno is non-zero and is not
> ENOENT. If the object could not be read because it does not exist,
> this is not considered a fatal error and we want to return NULL.
>
> Somewhere down the line, read_object calls git_open_noatime to open
> a pack index file, for example. We first try open with O_NOATIME.
> If O_NOATIME fails with EPERM, we retry without O_NOATIME. When the
> second open succeeds, errno is however still set to EPERM from the
> first attemt. When we finally determine that the object does not

> exist, read_object returns NULL and read_sha1_file_extended dies
> with a fatal error:
>
>     fatal: failed to read object <sha1>: Operation not permitted
>
> Fix this by resetting errno to zero before we call open again.
>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Clemens Buchacher <clemens.buchacher@intel.com>
> Helped-by: Martin Schröder <martin.h.schroeder@intel.com>