git-format-patch: add --output-directory long option again

Additionally notices and complains to an -o option without
directory or a duplicated -o option, -o and --stdout given
together.  Also delays the creation of directory until all
arguments are parsed, so that the command does not leave an
empty directory behind when it exits after seeing an unrelated
invalid option.

[jc: originally from Dennis Stosberg but with minor fixes, and
 documentation updates from Dennis.]

Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-format-patch.txt

@@ -40,8 +40,7 @@ OPTIONS
 -------
 -o|--output-directory <dir>::
 	Use <dir> to store the resulting files, instead of the
-	current working directory. This option is ignored if
-	--stdout is specified.
+	current working directory.
 
 -n|--numbered::
 	Name output in '[PATCH n/m]' format.

builtin-log.c

@@ -103,7 +103,7 @@ static int git_format_config(const char *var, const char *value)
 
 
 static FILE *realstdout = NULL;
-static char *output_directory = NULL;
+static const char *output_directory = NULL;
 
 static void reopen_stdout(struct commit *commit, int nr, int keep_subject)
 {
@@ -206,14 +206,14 @@ int cmd_format_patch(int argc, const char **argv, char **envp)
 			keep_subject = 1;
 			rev.total = -1;
 		}
-		else if (!strcmp(argv[i], "-o")) {
-			if (argc < 3)
-				die ("Which directory?");
-			if (mkdir(argv[i + 1], 0777) < 0 && errno != EEXIST)
-				die("Could not create directory %s",
-						argv[i + 1]);
-			output_directory = strdup(argv[i + 1]);
+		else if (!strcmp(argv[i], "--output-directory") ||
+			 !strcmp(argv[i], "-o")) {
 			i++;
+			if (argc <= i)
+				die("Which directory?");
+			if (output_directory)
+				die("Two output directories?");
+			output_directory = argv[i];
 		}
 		else if (!strcmp(argv[i], "--signoff") ||
 			 !strcmp(argv[i], "-s")) {
@@ -243,6 +243,14 @@ int cmd_format_patch(int argc, const char **argv, char **envp)
 	if (argc > 1)
 		die ("unrecognized argument: %s", argv[1]);
 
+	if (output_directory) {
+		if (use_stdout)
+			die("standard output, or directory, which one?");
+		if (mkdir(output_directory, 0777) < 0 && errno != EEXIST)
+			die("Could not create directory %s",
+			    output_directory);
+	}
+
 	if (rev.pending_objects && rev.pending_objects->next == NULL) {
 		rev.pending_objects->item->flags |= UNINTERESTING;
 		add_head(&rev);
@@ -293,8 +301,6 @@ int cmd_format_patch(int argc, const char **argv, char **envp)
 		if (!use_stdout)
 			fclose(stdout);
 	}
-	if (output_directory)
-		free(output_directory);
 	free(list);
 	return 0;
 }