format-patch: create leading components of output directory

'git format-patch -o <outdir>' did an equivalent of 'mkdir <outdir>'
not 'mkdir -p <outdir>', which is being corrected.

Avoid the usage of 'adjust_shared_perm' on the leading directories which
may have security implications. Achieved by temporarily disabling of
'config.sharedRepository' like 'git init' does.

Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config/format.txt

@@ -81,7 +81,7 @@ format.coverLetter::
 
 format.outputDirectory::
 	Set a custom directory to store the resulting files instead of the
-	current working directory.
+	current working directory. All directory components will be created.
 
 format.useAutoBase::
 	A boolean value which lets you enable the `--base=auto` option of

Documentation/git-format-patch.txt

@@ -66,7 +66,8 @@ they are created in the current working directory. The default path
 can be set with the `format.outputDirectory` configuration option.
 The `-o` option takes precedence over `format.outputDirectory`.
 To store patches in the current working directory even when
-`format.outputDirectory` points elsewhere, use `-o .`.
+`format.outputDirectory` points elsewhere, use `-o .`. All directory
+components will be created.
 
 By default, the subject of a single patch is "[PATCH] " followed by
 the concatenation of lines from the commit message up to the first blank

builtin/log.c

@@ -1765,10 +1765,26 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		setup_pager();
 
 	if (output_directory) {
+		int saved;
 		if (rev.diffopt.use_color != GIT_COLOR_ALWAYS)
 			rev.diffopt.use_color = GIT_COLOR_NEVER;
 		if (use_stdout)
 			die(_("standard output, or directory, which one?"));
+		/*
+		 * We consider <outdir> as 'outside of gitdir', therefore avoid
+		 * applying adjust_shared_perm in s-c-l-d.
+		 */
+		saved = get_shared_repository();
+		set_shared_repository(0);
+		switch (safe_create_leading_directories_const(output_directory)) {
+		case SCLD_OK:
+		case SCLD_EXISTS:
+			break;
+		default:
+			die(_("could not create leading directories "
+			      "of '%s'"), output_directory);
+		}
+		set_shared_repository(saved);
 		if (mkdir(output_directory, 0777) < 0 && errno != EEXIST)
 			die_errno(_("could not create directory '%s'"),
 				  output_directory);

t/t4014-format-patch.sh

@@ -1606,6 +1606,29 @@ test_expect_success 'From line has expected format' '
 	test_cmp from filtered
 '
 
+test_expect_success 'format-patch -o with no leading directories' '
+	rm -fr patches &&
+	git format-patch -o patches master..side &&
+	count=$(git rev-list --count master..side) &&
+	ls patches >list &&
+	test_line_count = $count list
+'
+
+test_expect_success 'format-patch -o with leading existing directories' '
+	git format-patch -o patches/side master..side &&
+	count=$(git rev-list --count master..side) &&
+	ls patches/side >list &&
+	test_line_count = $count list
+'
+
+test_expect_success 'format-patch -o with leading non-existing directories' '
+	rm -fr patches &&
+	git format-patch -o patches/side master..side &&
+	count=$(git rev-list --count master..side) &&
+	ls patches/side >list &&
+	test_line_count = $count list
+'
+
 test_expect_success 'format-patch format.outputDirectory option' '
 	test_config format.outputDirectory patches &&
 	rm -fr patches &&