format-patch: make output filename configurable

For the past 15 years, we've used the hardcoded 64 as the length
limit of the filename of the output from the "git format-patch"
command.  Since the value is shorter than the 80-column terminal, it
could grow without line wrapping a bit.  At the same time, since the
value is longer than half of the 80-column terminal, we could fit
two or more of them in "ls" output on such a terminal if we allowed
to lower it.

Introduce a new command line option --filename-max-length=<n> and a
new configuration variable format.filenameMaxLength to override the
hardcoded default.

While we are at it, remove a check that the name of output directory
does not exceed PATH_MAX---this check is pointless in that by the
time control reaches the function, the caller would already have
done an equivalent of "mkdir -p", so if the system does not like an
overly long directory name, the control wouldn't have reached here,
and otherwise, we know that the system allowed the output directory
to exist.  In the worst case, we will get an error when we try to
open the output file and handle the error correctly anyway.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 14 insertions, 6 deletions

diff --git a/builtin/log.c b/builtin/log.c
index 0a7ed4bef9..5790779c75 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -37,6 +37,7 @@
 
 #define MAIL_DEFAULT_WRAP 72
 #define COVER_FROM_AUTO_MAX_SUBJECT_LEN 100
+#define FORMAT_PATCH_NAME_MAX_DEFAULT 64
 
 /* Set a default date-time format for git log ("log.date" config variable) */
 static const char *default_date_mode = NULL;
@@ -50,6 +51,7 @@ static int decoration_style;
 static int decoration_given;
 static int use_mailmap_config = 1;
 static const char *fmt_patch_subject_prefix = "PATCH";
+static int fmt_patch_name_max = FORMAT_PATCH_NAME_MAX_DEFAULT;
 static const char *fmt_pretty;
 
 static const char * const builtin_log_usage[] = {
@@ -150,6 +152,7 @@ static void cmd_log_init_defaults(struct rev_info *rev)
 	rev->abbrev_commit = default_abbrev_commit;
 	rev->show_root_diff = default_show_root;
 	rev->subject_prefix = fmt_patch_subject_prefix;
+	rev->patch_name_max = fmt_patch_name_max;
 	rev->show_signature = default_show_signature;
 	rev->encode_email_headers = default_encode_email_headers;
 	rev->diffopt.flags.allow_textconv = 1;
@@ -454,6 +457,10 @@ static int git_log_config(const char *var, const char *value, void *cb)
 		return git_config_string(&fmt_pretty, var, value);
 	if (!strcmp(var, "format.subjectprefix"))
 		return git_config_string(&fmt_patch_subject_prefix, var, value);
+	if (!strcmp(var, "format.filenamemaxlength")) {
+		fmt_patch_name_max = git_config_int(var, value);
+		return 0;
+	}
 	if (!strcmp(var, "format.encodeemailheaders")) {
 		default_encode_email_headers = git_config_bool(var, value);
 		return 0;
@@ -955,15 +962,9 @@ static int open_next_file(struct commit *commit, const char *subject,
 			 struct rev_info *rev, int quiet)
 {
 	struct strbuf filename = STRBUF_INIT;
-	int suffix_len = strlen(rev->patch_suffix) + 1;
 
 	if (output_directory) {
 		strbuf_addstr(&filename, output_directory);
-		if (filename.len >=
-		    PATH_MAX - FORMAT_PATCH_NAME_MAX - suffix_len) {
-			strbuf_release(&filename);
-			return error(_("name of output directory is too long"));
-		}
 		strbuf_complete(&filename, '/');
 	}
 
@@ -1751,6 +1752,8 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			    N_("start numbering patches at <n> instead of 1")),
 		OPT_INTEGER('v', "reroll-count", &reroll_count,
 			    N_("mark the series as Nth re-roll")),
+		OPT_INTEGER(0, "filename-max-length", &fmt_patch_name_max,
+			    N_("max length of output filename")),
 		OPT_CALLBACK_F(0, "rfc", &rev, NULL,
 			    N_("Use [RFC PATCH] instead of [PATCH]"),
 			    PARSE_OPT_NOARG | PARSE_OPT_NONEG, rfc_callback),
@@ -1851,6 +1854,10 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			     PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN |
 			     PARSE_OPT_KEEP_DASHDASH);
 
+	/* Make sure "0000-$sub.patch" gives non-negative length for $sub */
+	if (fmt_patch_name_max <= strlen("0000-") + strlen(fmt_patch_suffix))
+		fmt_patch_name_max = strlen("0000-") + strlen(fmt_patch_suffix);
+
 	if (cover_from_description_arg)
 		cover_from_description_mode = parse_cover_from_description(cover_from_description_arg);
 
@@ -1935,6 +1942,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	rev.diffopt.output_format |= DIFF_FORMAT_PATCH;
 
 	rev.zero_commit = zero_commit;
+	rev.patch_name_max = fmt_patch_name_max;
 
 	if (!rev.diffopt.flags.text && !no_binary_diff)
 		rev.diffopt.flags.binary = 1;