Windows: redirect f[re]open("/dev/null") to f[re]open("nul")

On Windows, the equivalent of "/dev/null" is "nul". This implements
compatibility wrappers around fopen() and freopen() that check for this
particular file name.

The new tests exercise code paths where this is relevant.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

compat/mingw.c

@@ -140,6 +140,22 @@ int mingw_open (const char *filename, int oflags, ...)
 	return fd;
 }
 
+#undef fopen
+FILE *mingw_fopen (const char *filename, const char *otype)
+{
+	if (!strcmp(filename, "/dev/null"))
+		filename = "nul";
+	return fopen(filename, otype);
+}
+
+#undef freopen
+FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream)
+{
+	if (filename && !strcmp(filename, "/dev/null"))
+		filename = "nul";
+	return freopen(filename, otype, stream);
+}
+
 /*
  * The unit of FILETIME is 100-nanoseconds since January 1, 1601, UTC.
  * Returns the 100-nanoseconds ("hekto nanoseconds") since the epoch.

compat/mingw.h

@@ -170,6 +170,12 @@ int link(const char *oldpath, const char *newpath);
 int mingw_open (const char *filename, int oflags, ...);
 #define open mingw_open
 
+FILE *mingw_fopen (const char *filename, const char *otype);
+#define fopen mingw_fopen
+
+FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream);
+#define freopen mingw_freopen
+
 char *mingw_getcwd(char *pointer, int len);
 #define getcwd mingw_getcwd
 

t/t5510-fetch.sh

@@ -341,6 +341,13 @@ test_expect_success 'fetch into the current branch with --update-head-ok' '
 
 '
 
+test_expect_success 'fetch --dry-run' '
+
+	rm -f .git/FETCH_HEAD &&
+	git fetch --dry-run . &&
+	! test -f .git/FETCH_HEAD
+'
+
 test_expect_success "should be able to fetch with duplicate refspecs" '
         mkdir dups &&
         cd dups &&

t/t6023-merge-file.sh

@@ -64,6 +64,10 @@ cp new1.txt test.txt
 test_expect_success "merge without conflict" \
 	"git merge-file test.txt orig.txt new2.txt"
 
+cp new1.txt test.txt
+test_expect_success "merge without conflict (--quiet)" \
+	"git merge-file --quiet test.txt orig.txt new2.txt"
+
 cp new1.txt test2.txt
 test_expect_success "merge without conflict (missing LF at EOF)" \
 	"git merge-file test2.txt orig.txt new2.txt"