Re: [PATCH 05/20] rename_tmp_log(): use raceproof_create_file()

> Michael Haggerty <mhagger@alum.mit.edu> writes:
> 
>> Besides shortening the code, this saves an unnecessary call to
>> safe_create_leading_directories_const() in almost all cases.
>>
>> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
>> ---
>>  refs/files-backend.c | 76 ++++++++++++++++++++++------------------------------
>>  1 file changed, 32 insertions(+), 44 deletions(-)
>>
>> diff --git a/refs/files-backend.c b/refs/files-backend.c
>> index a549942..e5f964c 100644
>> --- a/refs/files-backend.c
>> +++ b/refs/files-backend.c
>> @@ -2400,55 +2400,43 @@ out:
>>   */
>>  #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
>>  
>> +static int rename_tmp_log_callback(const char *path, void *cb)
>> +{
>> +	int *true_errno = cb;
>> +
>> +	if (rename(git_path(TMP_RENAMED_LOG), path)) {
>> +		/*
>> +		 * rename(a, b) when b is an existing directory ought
>> +		 * to result in ISDIR, but Solaris 5.8 gives ENOTDIR.
>> +		 * Sheesh. Record the true errno for error reporting,
>> +		 * but report EISDIR to raceproof_create_file() so
>> +		 * that it knows to retry.
>> +		 */
>> +		*true_errno = errno;
>> +		if (errno==ENOTDIR)
>> +			errno = EISDIR;
> 
> Style: SP on both sides of a binary operator.

> [ENOTDIR]
>     A component of either path prefix names an existing file that is
>     neither a directory nor a symbolic link to a directory; or the old
>     argument names a directory and the new argument names a
>     non-directory file; or the old argument contains at least one non-
>     <slash> character and ends with one or more trailing <slash>
>     characters and the last pathname component names an existing file
>     that is neither a directory nor a symbolic link to a directory; or
>     the old argument names an existing non-directory file and the new
>     argument names a nonexistent file, contains at least one non-
>     <slash> character, and ends with one or more trailing <slash>
>     characters; or the new argument names an existing non-directory
>     file, contains at least one non- <slash> character, and ends with
>     one or more trailing <slash> characters.
> 
> i.e. when a leading component of "path" or TMP_RENAMED_LOG is an
> existing non-directory, we could get ENOTDIR on a valid system.
> 
> If another instance of Git created a file A/B when this process is
> trying to rename the temporary thing to its final location A/B/C,
> isn't that the errno we would see here?
>
> [EISDIR]
>     The new argument points to a directory and the old argument
>     points to a file that is not a directory.
>
> Puzzled...