commit: helper methods to reduce redundant blocks of code

* builtin/commit.c: Replace block of code with a one-liner call to
  logmsg_reencode().

* commit.c: new function for looking up a comit by name

* pretty.c: helper methods for getting output encodings

  Add helpers get_log_output_encoding() and
  get_commit_output_encoding() that eliminate some messy and duplicate
  if-blocks.

Signed-off-by: Pat Notz <patnotz@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit.c

@@ -896,30 +896,14 @@ static int parse_and_validate_options(int argc, const char *argv[],
 	if (!use_message && renew_authorship)
 		die("--reset-author can be used only with -C, -c or --amend.");
 	if (use_message) {
-		unsigned char sha1[20];
-		static char utf8[] = "UTF-8";
 		const char *out_enc;
-		char *enc, *end;
 		struct commit *commit;
 
-		if (get_sha1(use_message, sha1))
+		commit = lookup_commit_reference_by_name(use_message);
+		if (!commit)
 			die("could not lookup commit %s", use_message);
-		commit = lookup_commit_reference(sha1);
-		if (!commit || parse_commit(commit))
-			die("could not parse commit %s", use_message);
-
-		enc = strstr(commit->buffer, "\nencoding");
-		if (enc) {
-			end = strchr(enc + 10, '\n');
-			enc = xstrndup(enc + 10, end - (enc + 10));
-		} else {
-			enc = utf8;
-		}
-		out_enc = git_commit_encoding ? git_commit_encoding : utf8;
-
-		if (strcmp(out_enc, enc))
-			use_message_buffer =
-				reencode_string(commit->buffer, out_enc, enc);
+		out_enc = get_commit_output_encoding();
+		use_message_buffer = logmsg_reencode(commit, out_enc);
 
 		/*
 		 * If we failed to reencode the buffer, just copy it
@@ -929,8 +913,6 @@ static int parse_and_validate_options(int argc, const char *argv[],
 		 */
 		if (use_message_buffer == NULL)
 			use_message_buffer = xstrdup(commit->buffer);
-		if (enc != utf8)
-			free(enc);
 	}
 
 	if (!!also + !!only + !!all + !!interactive > 1)

builtin/log.c

@@ -329,8 +329,7 @@ static void show_tagger(char *buf, int len, struct rev_info *rev)
 	struct strbuf out = STRBUF_INIT;
 
 	pp_user_info("Tagger", rev->commit_format, &out, buf, rev->date_mode,
-		git_log_output_encoding ?
-		git_log_output_encoding: git_commit_encoding);
+		get_log_output_encoding());
 	printf("%s", out.buf);
 	strbuf_release(&out);
 }

builtin/mailinfo.c

@@ -1032,7 +1032,7 @@ int cmd_mailinfo(int argc, const char **argv, const char *prefix)
 	 */
 	git_config(git_mailinfo_config, NULL);
 
-	def_charset = (git_commit_encoding ? git_commit_encoding : "UTF-8");
+	def_charset = get_commit_output_encoding();
 	metainfo_charset = def_charset;
 
 	while (1 < argc && argv[1][0] == '-') {

cache.h

@@ -1003,6 +1003,9 @@ extern int git_env_bool(const char *, int);
 extern int git_config_system(void);
 extern int git_config_global(void);
 extern int config_error_nonbool(const char *);
+extern const char *get_log_output_encoding(void);
+extern const char *get_commit_output_encoding(void);
+
 extern const char *config_exclusive_filename;
 
 #define MAX_GITNAME (1000)

commit.c

@@ -49,6 +49,19 @@ struct commit *lookup_commit(const unsigned char *sha1)
 	return check_commit(obj, sha1, 0);
 }
 
+struct commit *lookup_commit_reference_by_name(const char *name)
+{
+	unsigned char sha1[20];
+	struct commit *commit;
+
+	if (get_sha1(name, sha1))
+		return NULL;
+	commit = lookup_commit_reference(sha1);
+	if (!commit || parse_commit(commit))
+		return NULL;
+	return commit;
+}
+
 static unsigned long parse_commit_date(const char *buf, const char *tail)
 {
 	const char *dateptr;

commit.h

@@ -36,6 +36,7 @@ struct commit *lookup_commit(const unsigned char *sha1);
 struct commit *lookup_commit_reference(const unsigned char *sha1);
 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
 					      int quiet);
+struct commit *lookup_commit_reference_by_name(const char *name);
 
 int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size);
 

environment.c

@@ -192,3 +192,14 @@ int set_git_dir(const char *path)
 	setup_git_env();
 	return 0;
 }
+
+const char *get_log_output_encoding(void)
+{
+	return git_log_output_encoding ? git_log_output_encoding
+		: get_commit_output_encoding();
+}
+
+const char *get_commit_output_encoding(void)
+{
+	return git_commit_encoding ? git_commit_encoding : "UTF-8";
+}

pretty.c

@@ -886,8 +886,7 @@ static size_t format_commit_one(struct strbuf *sb, const char *placeholder,
 	case 'N':
 		if (c->pretty_ctx->show_notes) {
 			format_display_notes(commit->object.sha1, sb,
-				    git_log_output_encoding ? git_log_output_encoding
-							    : git_commit_encoding, 0);
+				    get_log_output_encoding(), 0);
 			return 1;
 		}
 		return 0;
@@ -1159,11 +1158,7 @@ char *reencode_commit_message(const struct commit *commit, const char **encoding
 {
 	const char *encoding;
 
-	encoding = (git_log_output_encoding
-		    ? git_log_output_encoding
-		    : git_commit_encoding);
-	if (!encoding)
-		encoding = "UTF-8";
+	encoding = get_log_output_encoding();
 	if (encoding_p)
 		*encoding_p = encoding;
 	return logmsg_reencode(commit, encoding);