commit: give advice on empty amend
[gitweb.git] / builtin / revert.c
index eff52687a87b45b766e064eede7c2c35b6d133d2..7d68ef714eee5011d82952ca1829016c90827f61 100644 (file)
@@ -13,6 +13,7 @@
 #include "revision.h"
 #include "rerere.h"
 #include "merge-recursive.h"
+#include "refs.h"
 
 /*
  * This implements the builtins revert and cherry-pick.
@@ -35,7 +36,7 @@ static const char * const cherry_pick_usage[] = {
        NULL
 };
 
-static int edit, no_replay, no_commit, mainline, signoff;
+static int edit, no_replay, no_commit, mainline, signoff, allow_ff;
 static enum { REVERT, CHERRY_PICK } action;
 static struct commit *commit;
 static const char *commit_name;
@@ -45,6 +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 =
@@ -60,8 +63,19 @@ static void parse_args(int argc, const char **argv)
                OPT_INTEGER('m', "mainline", &mainline, "parent number"),
                OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
                OPT_END(),
+               OPT_END(),
+               OPT_END(),
        };
 
+       if (action == CHERRY_PICK) {
+               struct option cp_extra[] = {
+                       OPT_BOOLEAN(0, "ff", &allow_ff, "allow fast-forward"),
+                       OPT_END(),
+               };
+               if (parse_options_concat(options, ARRAY_SIZE(options), cp_extra))
+                       die("program error");
+       }
+
        if (parse_options(argc, argv, NULL, options, usage_str, 0) != 1)
                usage_with_options(usage_str, options);
 
@@ -73,33 +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)
@@ -244,14 +294,25 @@ static NORETURN void die_dirty_index(const char *me)
        }
 }
 
+static int fast_forward_to(const unsigned char *to, const unsigned char *from)
+{
+       struct ref_lock *ref_lock;
+
+       read_cache();
+       if (checkout_fast_forward(from, to))
+               exit(1); /* the callee should have complained already */
+       ref_lock = lock_any_ref_for_update("HEAD", from, 0);
+       return write_ref_sha1(ref_lock, to, "cherry-pick");
+}
+
 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;
-       char *defmsg = git_pathdup("MERGE_MSG");
+       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;
        static struct lock_file index_lock;
@@ -265,6 +326,17 @@ static int revert_or_cherry_pick(int argc, const char **argv)
        if (action == REVERT && !no_replay)
                die("revert is incompatible with replay");
 
+       if (allow_ff) {
+               if (signoff)
+                       die("cherry-pick --ff cannot be used with --signoff");
+               if (no_commit)
+                       die("cherry-pick --ff cannot be used with --no-commit");
+               if (no_replay)
+                       die("cherry-pick --ff cannot be used with -x");
+               if (edit)
+                       die("cherry-pick --ff cannot be used with --edit");
+       }
+
        if (read_cache() < 0)
                die("git %s: failed to read the index", me);
        if (no_commit) {
@@ -284,8 +356,6 @@ static int revert_or_cherry_pick(int argc, const char **argv)
        }
        discard_cache();
 
-       index_fd = hold_locked_index(&index_lock, 1);
-
        if (!commit->parents) {
                if (action == REVERT)
                        die ("Cannot revert a root commit");
@@ -314,14 +384,17 @@ static int revert_or_cherry_pick(int argc, const char **argv)
        else
                parent = commit->parents->item;
 
-       if (!(message = commit->buffer))
-               die ("Cannot get commit message for %s",
-                               sha1_to_hex(commit->object.sha1));
+       if (allow_ff && !hashcmp(parent->object.sha1, head))
+               return fast_forward_to(commit->object.sha1, head);
 
        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"
@@ -329,27 +402,19 @@ static int revert_or_cherry_pick(int argc, const char **argv)
         * reverse of it if we are revert.
         */
 
+       defmsg = git_pathdup("MERGE_MSG");
        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));
 
@@ -360,9 +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));
@@ -372,8 +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();
@@ -437,7 +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;