commit: give advice on empty amend
[gitweb.git] / builtin / revert.c
index 9a3c14c329713f16d14147b81a4b8031028a4f82..7d68ef714eee5011d82952ca1829016c90827f61 100644 (file)
@@ -46,6 +46,8 @@ static const char *me;
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
+static char *get_encoding(const char *message);
+
 static void parse_args(int argc, const char **argv)
 {
        const char * const * usage_str =
@@ -85,33 +87,69 @@ static void parse_args(int argc, const char **argv)
                exit(1);
 }
 
-static char *get_oneline(const char *message)
+struct commit_message {
+       char *parent_label;
+       const char *label;
+       const char *subject;
+       char *reencoded_message;
+       const char *message;
+};
+
+static int get_message(const char *raw_message, struct commit_message *out)
 {
-       char *result;
-       const char *p = message, *abbrev, *eol;
+       const char *encoding;
+       const char *p, *abbrev, *eol;
+       char *q;
        int abbrev_len, oneline_len;
 
-       if (!p)
-               die ("Could not read commit message of %s",
-                               sha1_to_hex(commit->object.sha1));
+       if (!raw_message)
+               return -1;
+       encoding = get_encoding(raw_message);
+       if (!encoding)
+               encoding = "UTF-8";
+       if (!git_commit_encoding)
+               git_commit_encoding = "UTF-8";
+
+       out->reencoded_message = NULL;
+       out->message = raw_message;
+       if (strcmp(encoding, git_commit_encoding))
+               out->reencoded_message = reencode_string(raw_message,
+                                       git_commit_encoding, encoding);
+       if (out->reencoded_message)
+               out->message = out->reencoded_message;
+
+       abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
+       abbrev_len = strlen(abbrev);
+
+       /* Find beginning and end of commit subject. */
+       p = out->message;
        while (*p && (*p != '\n' || p[1] != '\n'))
                p++;
-
        if (*p) {
                p += 2;
                for (eol = p + 1; *eol && *eol != '\n'; eol++)
                        ; /* do nothing */
        } else
                eol = p;
-       abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
-       abbrev_len = strlen(abbrev);
        oneline_len = eol - p;
-       result = xmalloc(abbrev_len + 5 + oneline_len);
-       memcpy(result, abbrev, abbrev_len);
-       memcpy(result + abbrev_len, "... ", 4);
-       memcpy(result + abbrev_len + 4, p, oneline_len);
-       result[abbrev_len + 4 + oneline_len] = '\0';
-       return result;
+
+       out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
+                             strlen("... ") + oneline_len + 1);
+       q = out->parent_label;
+       q = mempcpy(q, "parent of ", strlen("parent of "));
+       out->label = q;
+       q = mempcpy(q, abbrev, abbrev_len);
+       q = mempcpy(q, "... ", strlen("... "));
+       out->subject = q;
+       q = mempcpy(q, p, oneline_len);
+       *q = '\0';
+       return 0;
+}
+
+static void free_message(struct commit_message *msg)
+{
+       free(msg->parent_label);
+       free(msg->reencoded_message);
 }
 
 static char *get_encoding(const char *message)
@@ -271,9 +309,9 @@ static int revert_or_cherry_pick(int argc, const char **argv)
 {
        unsigned char head[20];
        struct commit *base, *next, *parent;
+       const char *base_label, *next_label;
        int i, index_fd, clean;
-       char *oneline, *reencoded_message = NULL;
-       const char *message, *encoding;
+       struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
        char *defmsg = NULL;
        struct merge_options o;
        struct tree *result, *next_tree, *base_tree, *head_tree;
@@ -349,14 +387,14 @@ static int revert_or_cherry_pick(int argc, const char **argv)
        if (allow_ff && !hashcmp(parent->object.sha1, head))
                return fast_forward_to(commit->object.sha1, head);
 
-       if (!(message = commit->buffer))
-               die ("Cannot get commit message for %s",
-                               sha1_to_hex(commit->object.sha1));
-
        if (parent && parse_commit(parent) < 0)
                die("%s: cannot parse parent commit %s",
                    me, sha1_to_hex(parent->object.sha1));
 
+       if (get_message(commit->buffer, &msg) != 0)
+               die("Cannot get commit message for %s",
+                               sha1_to_hex(commit->object.sha1));
+
        /*
         * "commit" is an existing commit.  We would want to apply
         * the difference it introduces since its first parent "prev"
@@ -368,26 +406,15 @@ static int revert_or_cherry_pick(int argc, const char **argv)
        msg_fd = hold_lock_file_for_update(&msg_file, defmsg,
                                           LOCK_DIE_ON_ERROR);
 
-       encoding = get_encoding(message);
-       if (!encoding)
-               encoding = "UTF-8";
-       if (!git_commit_encoding)
-               git_commit_encoding = "UTF-8";
-       if ((reencoded_message = reencode_string(message,
-                                       git_commit_encoding, encoding)))
-               message = reencoded_message;
-
-       oneline = get_oneline(message);
-
        index_fd = hold_locked_index(&index_lock, 1);
 
        if (action == REVERT) {
-               char *oneline_body = strchr(oneline, ' ');
-
                base = commit;
+               base_label = msg.label;
                next = parent;
+               next_label = msg.parent_label;
                add_to_msg("Revert \"");
-               add_to_msg(oneline_body + 1);
+               add_to_msg(msg.subject);
                add_to_msg("\"\n\nThis reverts commit ");
                add_to_msg(sha1_to_hex(commit->object.sha1));
 
@@ -398,9 +425,11 @@ static int revert_or_cherry_pick(int argc, const char **argv)
                add_to_msg(".\n");
        } else {
                base = parent;
+               base_label = msg.parent_label;
                next = commit;
-               set_author_ident_env(message);
-               add_message_to_msg(message);
+               next_label = msg.label;
+               set_author_ident_env(msg.message);
+               add_message_to_msg(msg.message);
                if (no_replay) {
                        add_to_msg("(cherry picked from commit ");
                        add_to_msg(sha1_to_hex(commit->object.sha1));
@@ -410,8 +439,9 @@ static int revert_or_cherry_pick(int argc, const char **argv)
 
        read_cache();
        init_merge_options(&o);
+       o.ancestor = base ? base_label : "(empty tree)";
        o.branch1 = "HEAD";
-       o.branch2 = oneline;
+       o.branch2 = next ? next_label : "(empty tree)";
 
        head_tree = parse_tree_indirect(head);
        next_tree = next ? next->tree : empty_tree();
@@ -475,7 +505,7 @@ static int revert_or_cherry_pick(int argc, const char **argv)
                args[i] = NULL;
                return execv_git_cmd(args);
        }
-       free(reencoded_message);
+       free_message(&msg);
        free(defmsg);
 
        return 0;