revert: use strbuf to refactor the code that writes the merge message

The code in this commit was written by Stephan Beyer for the sequencer
GSoC project:

    git://repo.or.cz/git/sbeyer.git

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/revert.c b/builtin/revert.c
index 1ddfac15b55a1b0bed7c7e359cb952749225a4f2..944c39a8ee9792948b7c0f52d53fced0ddc406d9 100644 (file)
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -157,28 +157,17 @@ static char *get_encoding(const char *message)
        return NULL;
 }
 
-static struct lock_file msg_file;
-static int msg_fd;
-
-static void add_to_msg(const char *string)
-{
-       int len = strlen(string);
-       if (write_in_full(msg_fd, string, len) < 0)
-               die_errno ("Could not write to MERGE_MSG");
-}
-
-static void add_message_to_msg(const char *message)
+static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 {
        const char *p = message;
        while (*p && (*p != '\n' || p[1] != '\n'))
                p++;
 
        if (!*p)
-               add_to_msg(sha1_to_hex(commit->object.sha1));
+               strbuf_addstr(msgbuf, sha1_to_hex(commit->object.sha1));
 
        p += 2;
-       add_to_msg(p);
-       return;
+       strbuf_addstr(msgbuf, p);
 }
 
 static void set_author_ident_env(const char *message)
@@ -254,6 +243,19 @@ static char *help_msg(const char *name)
        return strbuf_detach(&helpbuf, NULL);
 }
 
+static void write_message(struct strbuf *msgbuf, const char *filename)
+{
+       static struct lock_file msg_file;
+
+       int msg_fd = hold_lock_file_for_update(&msg_file, filename,
+                                              LOCK_DIE_ON_ERROR);
+       if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
+               die_errno("Could not write to %s.", filename);
+       strbuf_release(msgbuf);
+       if (commit_lock_file(&msg_file) < 0)
+               die("Error wrapping up %s", filename);
+}
+
 static struct tree *empty_tree(void)
 {
        struct tree *tree = xcalloc(1, sizeof(struct tree));
@@ -289,6 +291,7 @@ static int revert_or_cherry_pick(int argc, const char **argv)
        struct merge_options o;
        struct tree *result, *next_tree, *base_tree, *head_tree;
        static struct lock_file index_lock;
+       struct strbuf msgbuf = STRBUF_INIT;
 
        git_config(git_default_config, NULL);
        me = action == REVERT ? "revert" : "cherry-pick";
@@ -363,35 +366,32 @@ static int revert_or_cherry_pick(int argc, const char **argv)
         * reverse of it if we are revert.
         */
 
-       msg_fd = hold_lock_file_for_update(&msg_file, defmsg,
-                                          LOCK_DIE_ON_ERROR);
-
        if (action == REVERT) {
                base = commit;
                base_label = msg.label;
                next = parent;
                next_label = msg.parent_label;
-               add_to_msg("Revert \"");
-               add_to_msg(msg.subject);
-               add_to_msg("\"\n\nThis reverts commit ");
-               add_to_msg(sha1_to_hex(commit->object.sha1));
+               strbuf_addstr(&msgbuf, "Revert \"");
+               strbuf_addstr(&msgbuf, msg.subject);
+               strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
+               strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 
                if (commit->parents->next) {
-                       add_to_msg(", reversing\nchanges made to ");
-                       add_to_msg(sha1_to_hex(parent->object.sha1));
+                       strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
+                       strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
                }
-               add_to_msg(".\n");
+               strbuf_addstr(&msgbuf, ".\n");
        } else {
                base = parent;
                base_label = msg.parent_label;
                next = commit;
                next_label = msg.label;
                set_author_ident_env(msg.message);
-               add_message_to_msg(msg.message);
+               add_message_to_msg(&msgbuf, msg.message);
                if (no_replay) {
-                       add_to_msg("(cherry picked from commit ");
-                       add_to_msg(sha1_to_hex(commit->object.sha1));
-                       add_to_msg(")\n");
+                       strbuf_addstr(&msgbuf, "(cherry picked from commit ");
+                       strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
+                       strbuf_addstr(&msgbuf, ")\n");
                }
        }
 
@@ -416,27 +416,25 @@ static int revert_or_cherry_pick(int argc, const char **argv)
        rollback_lock_file(&index_lock);
 
        if (!clean) {
-               add_to_msg("\nConflicts:\n\n");
+               strbuf_addstr(&msgbuf, "\nConflicts:\n\n");
                for (i = 0; i < active_nr;) {
                        struct cache_entry *ce = active_cache[i++];
                        if (ce_stage(ce)) {
-                               add_to_msg("\t");
-                               add_to_msg(ce->name);
-                               add_to_msg("\n");
+                               strbuf_addch(&msgbuf, '\t');
+                               strbuf_addstr(&msgbuf, ce->name);
+                               strbuf_addch(&msgbuf, '\n');
                                while (i < active_nr && !strcmp(ce->name,
                                                active_cache[i]->name))
                                        i++;
                        }
                }
-               if (commit_lock_file(&msg_file) < 0)
-                       die ("Error wrapping up %s", defmsg);
+               write_message(&msgbuf, defmsg);
                fprintf(stderr, "Automatic %s failed.%s\n",
                        me, help_msg(commit_name));
                rerere(allow_rerere_auto);
                exit(1);
        }
-       if (commit_lock_file(&msg_file) < 0)
-               die ("Error wrapping up %s", defmsg);
+       write_message(&msgbuf, defmsg);
        fprintf(stderr, "Finished one %s.\n", me);
 
        /*