[PATCH v3 1/1] cygwin: Allow pushing to UNC paths

[tboegi@web.de]

From: Torsten Bögershausen <tboegi@web.de>

 cygwin can use an UNC path like //server/share/repo
 $ cd //server/share/dir
 $ mkdir test
 $ cd test
 $ git init --bare

 However, when we try to push from a local Git repository to this repo,
 there is a problem: Git converts the leading "//" into a single "/".

 As cygwin handles an UNC path so well, Git can support them better:
 - Introduce cygwin_offset_1st_component() which keeps the leading "//",
   similar to what Git for Windows does.
 - Move CYGWIN out of the POSIX in the tests for path normalization in t0060

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
---

I think I skip all the changing in setup.c and cygwin_access() for the
moment:
- It is not clear, what is a regression and what is an improvement
- It may be a problem that could be solved in cygwin itself
- I was able to push a an UNC path on a Windows server
  when the domain controller was reachable.


compat/cygwin.c       | 19 +++++++++++++++++++
 compat/cygwin.h       |  2 ++
 config.mak.uname      |  1 +
 git-compat-util.h     |  3 +++
 t/t0060-path-utils.sh |  2 ++
 5 files changed, 27 insertions(+)
 create mode 100644 compat/cygwin.c
 create mode 100644 compat/cygwin.h

diff --git a/compat/cygwin.c b/compat/cygwin.c
new file mode 100644
index 0000000..b9862d6
--- /dev/null
+++ b/compat/cygwin.c
@@ -0,0 +1,19 @@
+#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;
+}
diff --git a/compat/cygwin.h b/compat/cygwin.h
new file mode 100644
index 0000000..8e52de4
--- /dev/null
+++ b/compat/cygwin.h
@@ -0,0 +1,2 @@
+int cygwin_offset_1st_component(const char *path);
+#define offset_1st_component cygwin_offset_1st_component
diff --git a/config.mak.uname b/config.mak.uname
index adfb90b..551e465 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -184,6 +184,7 @@ ifeq ($(uname_O),Cygwin)
 	UNRELIABLE_FSTAT = UnfortunatelyYes
 	SPARSE_FLAGS = -isystem /usr/include/w32api -Wno-one-bit-signed-bitfield
 	OBJECT_CREATION_USES_RENAMES = UnfortunatelyNeedsTo
+	COMPAT_OBJS += compat/cygwin.o
 endif
 ifeq ($(uname_S),FreeBSD)
 	NEEDS_LIBICONV = YesPlease
diff --git a/git-compat-util.h b/git-compat-util.h
index 047172d..db9c22d 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -189,6 +189,9 @@
 #include <sys/sysctl.h>
 #endif
 
+#if defined(__CYGWIN__)
+#include "compat/cygwin.h"
+#endif
 #if defined(__MINGW32__)
 /* pull in Windows compatibility stuff */
 #include "compat/mingw.h"
diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index 444b5a4..7ea2bb5 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh
@@ -70,6 +70,8 @@ ancestor() {
 case $(uname -s) in
 *MINGW*)
 	;;
+*CYGWIN*)
+	;;
 *)
 	test_set_prereq POSIX
 	;;
-- 
2.10.0