Merge branch 'unc-path-w-backslashes'

This topic branch addresses a problem identified in
#439: while
cloning/fetching/pushing from "POSIX-ified UNC paths" (i.e. UNC paths
whose backslashes have been converted to forward slashes) works for some
time now, true UNC paths (with backslashes left intact) were handled
incorrectly. Example:

	git clone //myserver/folder/repo.git

works, but

	git clone \\myserver\folder\repo.git

(in CMD; in Git Bash, the backslashes would need to be doubled) used to
fail. The reason was an unexpected difference in command-line handling
between Win32 executables and MSYS2 ones (such as the shell that is used
by git-clone.exe to spawn git-upload-pack.exe).

This topic branch features a workaround *just* for the case where Git
passes stuff through sh.exe (which covers quite a few use cases,
though).

Signed-off-by: Johannes Schindelin <[email protected]>

compat/mingw.c

@@ -1066,7 +1066,7 @@ char *mingw_getcwd(char *pointer, int len)
  * See http://msdn2.microsoft.com/en-us/library/17w5ykft(vs.71).aspx
  * (Parsing C++ Command-Line Arguments)
  */
-static const char *quote_arg(const char *arg)
+static const char *quote_arg_msvc(const char *arg)
 {
 	/* count chars to quote */
 	int len = 0, n = 0;
@@ -1121,6 +1121,37 @@ static const char *quote_arg(const char *arg)
 	return q;
 }
 
+#include "quote.h"
+
+static const char *quote_arg_sh(const char *arg)
+{
+	struct strbuf buf = STRBUF_INIT;
+	const char *p2 = arg, *p;
+
+	for (p = arg; *p; p++) {
+		int ws = isspace(*p);
+		if (!ws && *p != '\\' && *p != '"')
+			continue;
+		if (!buf.len)
+			strbuf_addch(&buf, '"');
+		if (p != p2)
+			strbuf_add(&buf, p2, p - p2);
+		if (!ws)
+			strbuf_addch(&buf, '\\');
+		p2 = p;
+	}
+
+	if (p == arg)
+		strbuf_addch(&buf, '"');
+	else if (!buf.len)
+		return arg;
+	else
+		strbuf_add(&buf, p2, p - p2),
+
+	strbuf_addch(&buf, '"');
+	return strbuf_detach(&buf, 0);
+}
+
 static const char *parse_interpreter(const char *cmd)
 {
 	static char buf[100];
@@ -1547,6 +1578,8 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
 	BOOL ret;
 	HANDLE cons;
 	const char *strace_env;
+	const char *(*quote_arg)(const char *arg) =
+		*argv && !strcmp("sh", *argv) ? quote_arg_sh : quote_arg_msvc;
 
 	if (!atexit_handler_initialized) {
 		atexit_handler_initialized = 1;

t/t5580-clone-push-unc.sh

@@ -25,7 +25,7 @@ esac
 
 test_expect_success 'clone into absolute path lacking a drive prefix' '
 	USINGBACKSLASHES="$(echo "$WITHOUTDRIVE"/without-drive-prefix |
-		tr / \\)" &&
+		tr / \\\\)" &&
 	git clone . "$USINGBACKSLASHES" &&
 	test -f without-drive-prefix/.git/HEAD
 '
@@ -43,6 +43,11 @@ test_expect_success clone '
 	git clone "file://$UNCPATH" clone
 '
 
+test_expect_success 'clone with backslashed path' '
+	BACKSLASHED="$(echo "$UNCPATH" | tr / \\\\)" &&
+	git clone "$BACKSLASHED" backslashed
+'
+
 test_expect_success push '
 	(
 		cd clone &&