[PATCH 6/7] get_patch_filename(): split into two functions

[Junio C Hamano <gitster@pobox.com>]

The function switched between two operating modes depending on the
NULL-ness of its two parameters, as a hacky way to share small part
of implementation, sacrificing cleanliness of the API.

Implement "fmt_output_subject()" function that takes a subject
string and gives the name for the output file, and on top of it,
implement "fmt_output_commit()" function that takes a commit and
gives the name for the output file.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/log.c |  4 +++-
 log-tree.c    | 41 +++++++++++++++++++++++------------------
 log-tree.h    |  5 ++---
 3 files changed, 28 insertions(+), 22 deletions(-)

diff --git a/builtin/log.c b/builtin/log.c
index 3c6f20a..8cfb4da 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -686,8 +686,10 @@ static int reopen_stdout(struct commit *commit, const char *subject,
 
 	if (rev->numbered_files)
 		strbuf_addf(&filename, "%d", rev->nr);
+	else if (commit)
+		fmt_output_commit(&filename, commit, rev);
 	else
-		get_patch_filename(&filename, commit, subject, rev);
+		fmt_output_subject(&filename, subject, rev);
 
 	if (!quiet)
 		fprintf(realstdout, "%s\n", filename.buf + outdir_offset);
diff --git a/log-tree.c b/log-tree.c
index d9f86ce..670beae 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -299,26 +299,32 @@ static unsigned int digits_in_number(unsigned int number)
 	return result;
 }
 
-void get_patch_filename(struct strbuf *buf,
-			struct commit *commit, const char *subject,
+void fmt_output_subject(struct strbuf *filename,
+			const char *subject,
 			struct rev_info *info)
 {
 	const char *suffix = info->patch_suffix;
 	int nr = info->nr;
-	int suffix_len = strlen(suffix) + 1;
-	int start_len = buf->len;
-	int max_len = start_len + FORMAT_PATCH_NAME_MAX - suffix_len;
-
-	strbuf_addf(buf, "%04d-", nr);
-	if (subject)
-		strbuf_addstr(buf, subject);
-	else if (commit) {
-		struct pretty_print_context ctx = {0};
-		format_commit_message(commit, "%f", buf, &ctx);
-	}
-	if (max_len < buf->len)
-		strbuf_setlen(buf, max_len);
-	strbuf_addstr(buf, suffix);
+	int start_len = filename->len;
+	int max_len = start_len + FORMAT_PATCH_NAME_MAX - (strlen(suffix) + 1);
+
+	strbuf_addf(filename, "%04d-%s", nr, subject);
+
+	if (max_len < filename->len)
+		strbuf_setlen(filename, max_len);
+	strbuf_addstr(filename, suffix);
+}
+
+void fmt_output_commit(struct strbuf *filename,
+		       struct commit *commit,
+		       struct rev_info *info)
+{
+	struct pretty_print_context ctx = {0};
+	struct strbuf subject = STRBUF_INIT;
+
+	format_commit_message(commit, "%f", &subject, &ctx);
+	fmt_output_subject(filename, subject.buf, info);
+	strbuf_release(&subject);
 }
 
 void log_write_email_headers(struct rev_info *opt, struct commit *commit,
@@ -390,8 +396,7 @@ void log_write_email_headers(struct rev_info *opt, struct commit *commit,
 		if (opt->numbered_files)
 			strbuf_addf(&filename, "%d", opt->nr);
 		else
-			get_patch_filename(&filename, commit, NULL,
-					   opt);
+			fmt_output_commit(&filename, commit, opt);
 		snprintf(buffer, sizeof(buffer) - 1,
 			 "\n--%s%s\n"
 			 "Content-Type: text/x-patch;"
diff --git a/log-tree.h b/log-tree.h
index c6a944a..9140f48 100644
--- a/log-tree.h
+++ b/log-tree.h
@@ -21,8 +21,7 @@ void log_write_email_headers(struct rev_info *opt, struct commit *commit,
 void load_ref_decorations(int flags);
 
 #define FORMAT_PATCH_NAME_MAX 64
-void get_patch_filename(struct strbuf *buf,
-			struct commit *commit, const char *subject,
-			struct rev_info *);
+void fmt_output_commit(struct strbuf *, struct commit *, struct rev_info *);
+void fmt_output_subject(struct strbuf *, const char *subject, struct rev_info *);
 
 #endif
-- 
1.8.0.6.gd28b5d4.dirty