From: Junio C Hamano <gitster@pobox.com>
Date: Thu, 12 Sep 2013 19:11:15 GMT
Subject: Re: [PATCH 1/2] relative_path should honor dos_drive_prefix
Message-ID: <xmqq8uz1q2i4.fsf@gitster.dls.corp.google.com>
In-Reply-To: <5231F839.3080208@kdbg.org>

Johannes Sixt <j6t@kdbg.org> writes:

> Am 12.09.2013 16:13, schrieb Torsten Bögershausen:
>> On 2013-09-12 11.12, Jiang Xin wrote:
>>> +static int have_same_root(const char *path1, const char *path2)
>>> +{
>>> +	int is_abs1, is_abs2;
>>> +
>>> +	is_abs1 = is_absolute_path(path1);
>>> +	is_abs2 = is_absolute_path(path2);
>>> +	return (is_abs1 && is_abs2 && !strncasecmp(path1, path2, 1)) ||
>>                                        ^^^^^^^^^^^
>> I wonder: should strncasecmp() be replaced with strncmp_icase() ?
>
> I don't think so: On POSIX, it is irrelevant, because the call will only
> compare a slash to a slash. On Windows, it compares the drive letters
> (or a slash); it is *always* case-insensitive, even if the volume
> mounted is NTFS with case-sensitivity enabled and core.ignorecase is false.

Ah, you are right, of course.  We could even do

	tolower(path1[0]) == tolower(path2[0])

which might be more explicit.

For systems that need POSIX escape hatch for Apollo Domain ;-), we
would need a bit more work.  When both path1 and path2 begin with a
double-dash, we would need to check if they match up to the next
slash, so that

 - //host1/usr/src and //host1/usr/lib share the same root and the
   former can be made to ../src relative to the latter;

 - //host1/usr/src and //host2/usr/lib are of separate roots.

or something.