hash-object: always try to set up the git repository

When "hash-object" is run without "-w", we don't need to be
in a git repository at all; we can just hash the object and
write its sha1 to stdout. However, if we _are_ in a git
repository, we would want to know that so we can follow the
normal rules for respecting config, .gitattributes, etc.

This happens to work at the top-level of a git repository
because we blindly read ".git/config", but as the included
test shows, it does not work when you are in a subdirectory.

The solution is to just do a "gentle" setup in this case. We
already take care to use prefix_filename() on any filename
arguments we get (to handle the "-w" case), so we don't need
to do anything extra to handle the side effects of repo
setup.

An alternative would be to specify RUN_SETUP_GENTLY for this
command in git.c, and then die if "-w" is set but we are not
in a repository. However, the error messages generated at
the time of setup_git_directory() are more detailed, so it's
better to find out which mode we are in, and then call the
appropriate function.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin/hash-object.c

@@ -87,6 +87,7 @@ int cmd_hash_object(int argc, const char **argv, const char *prefix)
 	int stdin_paths = 0;
 	int no_filters = 0;
 	int literally = 0;
+	int nongit = 0;
 	unsigned flags = HASH_FORMAT_CHECK;
 	const char *vpath = NULL;
 	const struct option hash_object_options[] = {
@@ -107,12 +108,14 @@ int cmd_hash_object(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, NULL, hash_object_options,
 			     hash_object_usage, 0);
 
-	if (flags & HASH_WRITE_OBJECT) {
+	if (flags & HASH_WRITE_OBJECT)
 		prefix = setup_git_directory();
-		prefix_length = prefix ? strlen(prefix) : 0;
-		if (vpath && prefix)
-			vpath = prefix_filename(prefix, prefix_length, vpath);
-	}
+	else
+		prefix = setup_git_directory_gently(&nongit);
+
+	prefix_length = prefix ? strlen(prefix) : 0;
+	if (vpath && prefix)
+		vpath = prefix_filename(prefix, prefix_length, vpath);
 
 	git_config(git_default_config, NULL);
 

t/t1007-hash-object.sh

@@ -121,6 +121,17 @@ test_expect_success 'check that appropriate filter is invoke when --path is used
 	git config --unset core.autocrlf
 '
 
+test_expect_success 'gitattributes also work in a subdirectory' '
+	mkdir subdir &&
+	(
+		cd subdir &&
+		subdir_sha0=$(git hash-object ../file0) &&
+		subdir_sha1=$(git hash-object ../file1) &&
+		test "$file0_sha" = "$subdir_sha0" &&
+		test "$file1_sha" = "$subdir_sha1"
+	)
+'
+
 test_expect_success 'check that --no-filters option works' '
 	echo fooQ | tr Q "\\015" >file0 &&
 	cp file0 file1 &&