git clone <url> C:\cygwin\home\USER\repo' is working (again)

A regression for cygwin users was introduced with commit 05b458c,
 "real_path: resolve symlinks by hand".

In the the commit message we read:
  The current implementation of real_path uses chdir() in order to resolve
    symlinks.  Unfortunately this isn't thread-safe as chdir() affects a
      process as a whole...

The old (and non-thread-save) OS calls chdir()/pwd() had been
replaced by a string operation.
The cygwin layer "knows" that "C:\cygwin" is an absolute path,
but the new string operation does not.

"git clone <url> C:\cygwin\home\USER\repo" fails like this:
fatal: Invalid path '/home/USER/repo/C:\cygwin\home\USER\repo'

The solution is to implement has_dos_drive_prefix(), skip_dos_drive_prefix()
is_dir_sep(), offset_1st_component() and convert_slashes() for cygwin
in the same way as it is done in 'Git for Windows' in compat/mingw.[ch]

Extract the needed code into compat/win32/path-utils.[ch] and use it
for cygwin as well.

Reported-by: Steven Penny <svnpenn@gmail.com>
Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 0 insertions, 19 deletions

diff --git a/compat/cygwin.c b/compat/cygwin.c
deleted file mode 100644
index b9862d6..0000000
--- a/compat/cygwin.c
+++ /dev/null
@@ -1,19 +0,0 @@
-#include "../git-compat-util.h"
-#include "../cache.h"
-
-int cygwin_offset_1st_component(const char *path)
-{
-	const char *pos = path;
-	/* unc paths */
-	if (is_dir_sep(pos[0]) && is_dir_sep(pos[1])) {
-		/* skip server name */
-		pos = strchr(pos + 2, '/');
-		if (!pos)
-			return 0; /* Error: malformed unc path */
-
-		do {
-			pos++;
-		} while (*pos && pos[0] != '/');
-	}
-	return pos + is_dir_sep(*pos) - path;
-}