log-tree: factor out fmt_output_email_subject()

Use a strbuf to store the subject prefix string and move its
construction into its own function.  This gets rid of two arbitrary
length limits and allows the string to be added by callers directly.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 21 insertions, 20 deletions

diff --git a/log-tree.c b/log-tree.c
index 8c2415747a..44febb75ab 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -332,35 +332,33 @@ void fmt_output_commit(struct strbuf *filename,
 	strbuf_release(&subject);
 }
 
+void fmt_output_email_subject(struct strbuf *sb, struct rev_info *opt)
+{
+	if (opt->total > 0) {
+		strbuf_addf(sb, "Subject: [%s%s%0*d/%d] ",
+			    opt->subject_prefix,
+			    *opt->subject_prefix ? " " : "",
+			    digits_in_number(opt->total),
+			    opt->nr, opt->total);
+	} else if (opt->total == 0 && opt->subject_prefix && *opt->subject_prefix) {
+		strbuf_addf(sb, "Subject: [%s] ",
+			    opt->subject_prefix);
+	} else {
+		strbuf_addstr(sb, "Subject: ");
+	}
+}
+
 void log_write_email_headers(struct rev_info *opt, struct commit *commit,
 			     const char **subject_p,
 			     const char **extra_headers_p,
 			     int *need_8bit_cte_p)
 {
-	const char *subject = NULL;
+	static struct strbuf subject = STRBUF_INIT;
 	const char *extra_headers = opt->extra_headers;
 	const char *name = oid_to_hex(opt->zero_commit ?
 				      &null_oid : &commit->object.oid);
 
 	*need_8bit_cte_p = 0; /* unknown */
-	if (opt->total > 0) {
-		static char buffer[64];
-		snprintf(buffer, sizeof(buffer),
-			 "Subject: [%s%s%0*d/%d] ",
-			 opt->subject_prefix,
-			 *opt->subject_prefix ? " " : "",
-			 digits_in_number(opt->total),
-			 opt->nr, opt->total);
-		subject = buffer;
-	} else if (opt->total == 0 && opt->subject_prefix && *opt->subject_prefix) {
-		static char buffer[256];
-		snprintf(buffer, sizeof(buffer),
-			 "Subject: [%s] ",
-			 opt->subject_prefix);
-		subject = buffer;
-	} else {
-		subject = "Subject: ";
-	}
 
 	fprintf(opt->diffopt.file, "From %s Mon Sep 17 00:00:00 2001\n", name);
 	graph_show_oneline(opt->graph);
@@ -417,7 +415,9 @@ void log_write_email_headers(struct rev_info *opt, struct commit *commit,
 		opt->diffopt.stat_sep = buffer;
 		strbuf_release(&filename);
 	}
-	*subject_p = subject;
+	strbuf_reset(&subject);
+	fmt_output_email_subject(&subject, opt);
+	*subject_p = subject.buf;
 	*extra_headers_p = extra_headers;
 }
 
diff --git a/log-tree.h b/log-tree.h
index c8116e60cd..dd75dd7770 100644
--- a/log-tree.h
+++ b/log-tree.h
@@ -30,5 +30,6 @@ void load_ref_decorations(int flags);
 #define FORMAT_PATCH_NAME_MAX 64
 void fmt_output_commit(struct strbuf *, struct commit *, struct rev_info *);
 void fmt_output_subject(struct strbuf *, const char *subject, struct rev_info *);
+void fmt_output_email_subject(struct strbuf *, struct rev_info *);
 
 #endif