Code

branch: allow a no-op "branch -M <current-branch> HEAD"
[git.git] / builtin / merge.c
index ab4077f272919fb47e3c5f179dc42fc9baad68bb..2870a6af6fbc868455f2961483cfbfdb065a1a14 100644 (file)
@@ -46,11 +46,10 @@ static const char * const builtin_merge_usage[] = {
 
 static int show_diffstat = 1, shortlog_len, squash;
 static int option_commit = 1, allow_fast_forward = 1;
-static int fast_forward_only;
+static int fast_forward_only, option_edit;
 static int allow_trivial = 1, have_message;
 static struct strbuf merge_msg;
 static struct commit_list *remoteheads;
-static unsigned char head[20], stash[20];
 static struct strategy **use_strategies;
 static size_t use_strategies_nr, use_strategies_alloc;
 static const char **xopts;
@@ -190,6 +189,8 @@ static struct option builtin_merge_options[] = {
                "create a single commit instead of doing a merge"),
        OPT_BOOLEAN(0, "commit", &option_commit,
                "perform a commit if the merge succeeds (default)"),
+       OPT_BOOLEAN('e', "edit", &option_edit,
+               "edit message before committing"),
        OPT_BOOLEAN(0, "ff", &allow_fast_forward,
                "allow fast-forward (default)"),
        OPT_BOOLEAN(0, "ff-only", &fast_forward_only,
@@ -217,7 +218,7 @@ static void drop_save(void)
        unlink(git_path("MERGE_MODE"));
 }
 
-static void save_state(void)
+static int save_state(unsigned char *stash)
 {
        int len;
        struct child_process cp;
@@ -236,11 +237,12 @@ static void save_state(void)
 
        if (finish_command(&cp) || len < 0)
                die(_("stash failed"));
-       else if (!len)
-               return;
+       else if (!len)          /* no changes */
+               return -1;
        strbuf_setlen(&buffer, buffer.len-1);
        if (get_sha1(buffer.buf, stash))
                die(_("not a valid object: %s"), buffer.buf);
+       return 0;
 }
 
 static void read_empty(unsigned const char *sha1, int verbose)
@@ -278,7 +280,8 @@ static void reset_hard(unsigned const char *sha1, int verbose)
                die(_("read-tree failed"));
 }
 
-static void restore_state(void)
+static void restore_state(const unsigned char *head,
+                         const unsigned char *stash)
 {
        struct strbuf sb = STRBUF_INIT;
        const char *args[] = { "stash", "apply", NULL, NULL };
@@ -308,25 +311,25 @@ static void finish_up_to_date(const char *msg)
        drop_save();
 }
 
-static void squash_message(void)
+static void squash_message(struct commit *commit)
 {
        struct rev_info rev;
-       struct commit *commit;
        struct strbuf out = STRBUF_INIT;
        struct commit_list *j;
+       const char *filename;
        int fd;
        struct pretty_print_context ctx = {0};
 
        printf(_("Squash commit -- not updating HEAD\n"));
-       fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
+       filename = git_path("SQUASH_MSG");
+       fd = open(filename, O_WRONLY | O_CREAT, 0666);
        if (fd < 0)
-               die_errno(_("Could not write to '%s'"), git_path("SQUASH_MSG"));
+               die_errno(_("Could not write to '%s'"), filename);
 
        init_revisions(&rev, NULL);
        rev.ignore_merges = 1;
        rev.commit_format = CMIT_FMT_MEDIUM;
 
-       commit = lookup_commit(head);
        commit->object.flags |= UNINTERESTING;
        add_pending_object(&rev, &commit->object, NULL);
 
@@ -355,9 +358,11 @@ static void squash_message(void)
        strbuf_release(&out);
 }
 
-static void finish(const unsigned char *new_head, const char *msg)
+static void finish(struct commit *head_commit,
+                  const unsigned char *new_head, const char *msg)
 {
        struct strbuf reflog_message = STRBUF_INIT;
+       const unsigned char *head = head_commit->object.sha1;
 
        if (!msg)
                strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
@@ -368,7 +373,7 @@ static void finish(const unsigned char *new_head, const char *msg)
                        getenv("GIT_REFLOG_ACTION"), msg);
        }
        if (squash) {
-               squash_message();
+               squash_message(head_commit);
        } else {
                if (verbosity >= 0 && !merge_msg.len)
                        printf(_("No merge message -- not updating HEAD\n"));
@@ -403,6 +408,16 @@ static void finish(const unsigned char *new_head, const char *msg)
        strbuf_release(&reflog_message);
 }
 
+static struct object *want_commit(const char *name)
+{
+       struct object *obj;
+       unsigned char sha1[20];
+       if (get_sha1(name, sha1))
+               return NULL;
+       obj = parse_object(sha1);
+       return peel_to_type(name, 0, obj, OBJ_COMMIT);
+}
+
 /* Get the name for the merge commit's message. */
 static void merge_name(const char *remote, struct strbuf *msg)
 {
@@ -418,7 +433,7 @@ static void merge_name(const char *remote, struct strbuf *msg)
        remote = bname.buf;
 
        memset(branch_head, 0, sizeof(branch_head));
-       remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
+       remote_head = want_commit(remote);
        if (!remote_head)
                die(_("'%s' does not point to a commit"), remote);
 
@@ -479,14 +494,16 @@ static void merge_name(const char *remote, struct strbuf *msg)
 
        if (!strcmp(remote, "FETCH_HEAD") &&
                        !access(git_path("FETCH_HEAD"), R_OK)) {
+               const char *filename;
                FILE *fp;
                struct strbuf line = STRBUF_INIT;
                char *ptr;
 
-               fp = fopen(git_path("FETCH_HEAD"), "r");
+               filename = git_path("FETCH_HEAD");
+               fp = fopen(filename, "r");
                if (!fp)
                        die_errno(_("could not open '%s' for reading"),
-                                 git_path("FETCH_HEAD"));
+                                 filename);
                strbuf_getline(&line, fp, '\n');
                fclose(fp);
                ptr = strstr(line.buf, "\tnot-for-merge\t");
@@ -661,7 +678,7 @@ int try_merge_command(const char *strategy, size_t xopts_nr,
 }
 
 static int try_merge_strategy(const char *strategy, struct commit_list *common,
-                             const char *head_arg)
+                             struct commit *head, const char *head_arg)
 {
        int index_fd;
        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
@@ -707,7 +724,7 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
                        commit_list_insert(j->item, &reversed);
 
                index_fd = hold_locked_index(lock, 1);
-               clean = merge_recursive(&o, lookup_commit(head),
+               clean = merge_recursive(&o, head,
                                remoteheads->item, reversed, &result);
                if (active_cache_changed &&
                                (write_cache(index_fd, active_cache, active_nr) ||
@@ -832,51 +849,78 @@ static void add_strategies(const char *string, unsigned attr)
 
 }
 
-static void write_merge_msg(void)
+static void write_merge_msg(struct strbuf *msg)
 {
-       int fd = open(git_path("MERGE_MSG"), O_WRONLY | O_CREAT, 0666);
+       const char *filename = git_path("MERGE_MSG");
+       int fd = open(filename, O_WRONLY | O_CREAT, 0666);
        if (fd < 0)
                die_errno(_("Could not open '%s' for writing"),
-                         git_path("MERGE_MSG"));
-       if (write_in_full(fd, merge_msg.buf, merge_msg.len) != merge_msg.len)
-               die_errno(_("Could not write to '%s'"), git_path("MERGE_MSG"));
+                         filename);
+       if (write_in_full(fd, msg->buf, msg->len) != msg->len)
+               die_errno(_("Could not write to '%s'"), filename);
        close(fd);
 }
 
-static void read_merge_msg(void)
+static void read_merge_msg(struct strbuf *msg)
 {
-       strbuf_reset(&merge_msg);
-       if (strbuf_read_file(&merge_msg, git_path("MERGE_MSG"), 0) < 0)
-               die_errno(_("Could not read from '%s'"), git_path("MERGE_MSG"));
+       const char *filename = git_path("MERGE_MSG");
+       strbuf_reset(msg);
+       if (strbuf_read_file(msg, filename, 0) < 0)
+               die_errno(_("Could not read from '%s'"), filename);
 }
 
-static void run_prepare_commit_msg(void)
+static void write_merge_state(void);
+static void abort_commit(const char *err_msg)
 {
-       write_merge_msg();
+       if (err_msg)
+               error("%s", err_msg);
+       fprintf(stderr,
+               _("Not committing merge; use 'git commit' to complete the merge.\n"));
+       write_merge_state();
+       exit(1);
+}
+
+static void prepare_to_commit(void)
+{
+       struct strbuf msg = STRBUF_INIT;
+       strbuf_addbuf(&msg, &merge_msg);
+       strbuf_addch(&msg, '\n');
+       write_merge_msg(&msg);
        run_hook(get_index_file(), "prepare-commit-msg",
                 git_path("MERGE_MSG"), "merge", NULL, NULL);
-       read_merge_msg();
+       if (option_edit) {
+               if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
+                       abort_commit(NULL);
+       }
+       read_merge_msg(&msg);
+       stripspace(&msg, option_edit);
+       if (!msg.len)
+               abort_commit(_("Empty commit message."));
+       strbuf_release(&merge_msg);
+       strbuf_addbuf(&merge_msg, &msg);
+       strbuf_release(&msg);
 }
 
-static int merge_trivial(void)
+static int merge_trivial(struct commit *head)
 {
        unsigned char result_tree[20], result_commit[20];
        struct commit_list *parent = xmalloc(sizeof(*parent));
 
        write_tree_trivial(result_tree);
        printf(_("Wonderful.\n"));
-       parent->item = lookup_commit(head);
+       parent->item = head;
        parent->next = xmalloc(sizeof(*parent->next));
        parent->next->item = remoteheads->item;
        parent->next->next = NULL;
-       run_prepare_commit_msg();
+       prepare_to_commit();
        commit_tree(merge_msg.buf, result_tree, parent, result_commit, NULL);
-       finish(result_commit, "In-index merge");
+       finish(head, result_commit, "In-index merge");
        drop_save();
        return 0;
 }
 
-static int finish_automerge(struct commit_list *common,
+static int finish_automerge(struct commit *head,
+                           struct commit_list *common,
                            unsigned char *result_tree,
                            const char *wt_strategy)
 {
@@ -887,22 +931,22 @@ static int finish_automerge(struct commit_list *common,
        free_commit_list(common);
        if (allow_fast_forward) {
                parents = remoteheads;
-               commit_list_insert(lookup_commit(head), &parents);
+               commit_list_insert(head, &parents);
                parents = reduce_heads(parents);
        } else {
                struct commit_list **pptr = &parents;
 
-               pptr = &commit_list_insert(lookup_commit(head),
+               pptr = &commit_list_insert(head,
                                pptr)->next;
                for (j = remoteheads; j; j = j->next)
                        pptr = &commit_list_insert(j->item, pptr)->next;
        }
-       free_commit_list(remoteheads);
        strbuf_addch(&merge_msg, '\n');
-       run_prepare_commit_msg();
+       prepare_to_commit();
+       free_commit_list(remoteheads);
        commit_tree(merge_msg.buf, result_tree, parents, result_commit, NULL);
        strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
-       finish(result_commit, buf.buf);
+       finish(head, result_commit, buf.buf);
        strbuf_release(&buf);
        drop_save();
        return 0;
@@ -910,13 +954,14 @@ static int finish_automerge(struct commit_list *common,
 
 static int suggest_conflicts(int renormalizing)
 {
+       const char *filename;
        FILE *fp;
        int pos;
 
-       fp = fopen(git_path("MERGE_MSG"), "a");
+       filename = git_path("MERGE_MSG");
+       fp = fopen(filename, "a");
        if (!fp)
-               die_errno(_("Could not open '%s' for writing"),
-                         git_path("MERGE_MSG"));
+               die_errno(_("Could not open '%s' for writing"), filename);
        fprintf(fp, "\nConflicts:\n");
        for (pos = 0; pos < active_nr; pos++) {
                struct cache_entry *ce = active_cache[pos];
@@ -936,7 +981,8 @@ static int suggest_conflicts(int renormalizing)
        return 1;
 }
 
-static struct commit *is_old_style_invocation(int argc, const char **argv)
+static struct commit *is_old_style_invocation(int argc, const char **argv,
+                                             const unsigned char *head)
 {
        struct commit *second_token = NULL;
        if (argc > 2) {
@@ -1005,12 +1051,47 @@ static int setup_with_upstream(const char ***argv)
        return i;
 }
 
+static void write_merge_state(void)
+{
+       const char *filename;
+       int fd;
+       struct commit_list *j;
+       struct strbuf buf = STRBUF_INIT;
+
+       for (j = remoteheads; j; j = j->next)
+               strbuf_addf(&buf, "%s\n",
+                       sha1_to_hex(j->item->object.sha1));
+       filename = git_path("MERGE_HEAD");
+       fd = open(filename, O_WRONLY | O_CREAT, 0666);
+       if (fd < 0)
+               die_errno(_("Could not open '%s' for writing"), filename);
+       if (write_in_full(fd, buf.buf, buf.len) != buf.len)
+               die_errno(_("Could not write to '%s'"), filename);
+       close(fd);
+       strbuf_addch(&merge_msg, '\n');
+       write_merge_msg(&merge_msg);
+
+       filename = git_path("MERGE_MODE");
+       fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
+       if (fd < 0)
+               die_errno(_("Could not open '%s' for writing"), filename);
+       strbuf_reset(&buf);
+       if (!allow_fast_forward)
+               strbuf_addf(&buf, "no-ff");
+       if (write_in_full(fd, buf.buf, buf.len) != buf.len)
+               die_errno(_("Could not write to '%s'"), filename);
+       close(fd);
+}
+
 int cmd_merge(int argc, const char **argv, const char *prefix)
 {
        unsigned char result_tree[20];
+       unsigned char stash[20];
+       unsigned char head_sha1[20];
+       struct commit *head_commit;
        struct strbuf buf = STRBUF_INIT;
        const char *head_arg;
-       int flag, head_invalid = 0, i;
+       int flag, i;
        int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
        struct commit_list *common = NULL;
        const char *best_strategy = NULL, *wt_strategy = NULL;
@@ -1023,11 +1104,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
         * Check if we are _not_ on a detached HEAD, i.e. if there is a
         * current branch.
         */
-       branch = resolve_ref("HEAD", head, 0, &flag);
+       branch = resolve_ref("HEAD", head_sha1, 0, &flag);
        if (branch && !prefixcmp(branch, "refs/heads/"))
                branch += 11;
-       if (is_null_sha1(head))
-               head_invalid = 1;
+       if (!branch || is_null_sha1(head_sha1))
+               head_commit = NULL;
+       else
+               head_commit = lookup_commit_or_die(head_sha1, "HEAD");
 
        git_config(git_merge_config, NULL);
 
@@ -1104,12 +1187,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
         * additional safety measure to check for it.
         */
 
-       if (!have_message && is_old_style_invocation(argc, argv)) {
+       if (!have_message && head_commit &&
+           is_old_style_invocation(argc, argv, head_commit->object.sha1)) {
                strbuf_addstr(&merge_msg, argv[0]);
                head_arg = argv[1];
                argv += 2;
                argc -= 2;
-       } else if (head_invalid) {
+       } else if (!head_commit) {
                struct object *remote_head;
                /*
                 * If the merged head is a valid one there is no reason
@@ -1124,7 +1208,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                if (!allow_fast_forward)
                        die(_("Non-fast-forward commit does not make sense into "
                            "an empty head"));
-               remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
+               remote_head = want_commit(argv[0]);
                if (!remote_head)
                        die(_("%s - not something we can merge"), argv[0]);
                read_empty(remote_head->sha1, 0);
@@ -1156,7 +1240,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                }
        }
 
-       if (head_invalid || !argc)
+       if (!head_commit || !argc)
                usage_with_options(builtin_merge_usage,
                        builtin_merge_options);
 
@@ -1170,7 +1254,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                struct object *o;
                struct commit *commit;
 
-               o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
+               o = want_commit(argv[i]);
                if (!o)
                        die(_("%s - not something we can merge"), argv[i]);
                commit = lookup_commit(o->sha1);
@@ -1197,17 +1281,16 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
        }
 
        if (!remoteheads->next)
-               common = get_merge_bases(lookup_commit(head),
-                               remoteheads->item, 1);
+               common = get_merge_bases(head_commit, remoteheads->item, 1);
        else {
                struct commit_list *list = remoteheads;
-               commit_list_insert(lookup_commit(head), &list);
+               commit_list_insert(head_commit, &list);
                common = get_octopus_merge_bases(list);
                free(list);
        }
 
-       update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
-               DIE_ON_ERR);
+       update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
+                  NULL, 0, DIE_ON_ERR);
 
        if (!common)
                ; /* No common ancestors found. We need a real merge. */
@@ -1221,13 +1304,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                return 0;
        } else if (allow_fast_forward && !remoteheads->next &&
                        !common->next &&
-                       !hashcmp(common->item->object.sha1, head)) {
+                       !hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
                /* Again the most common case of merging one remote. */
                struct strbuf msg = STRBUF_INIT;
                struct object *o;
                char hex[41];
 
-               strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
+               strcpy(hex, find_unique_abbrev(head_commit->object.sha1, DEFAULT_ABBREV));
 
                if (verbosity >= 0)
                        printf(_("Updating %s..%s\n"),
@@ -1238,15 +1321,14 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                if (have_message)
                        strbuf_addstr(&msg,
                                " (no commit created; -m option ignored)");
-               o = peel_to_type(sha1_to_hex(remoteheads->item->object.sha1),
-                       0, NULL, OBJ_COMMIT);
+               o = want_commit(sha1_to_hex(remoteheads->item->object.sha1));
                if (!o)
                        return 1;
 
-               if (checkout_fast_forward(head, remoteheads->item->object.sha1))
+               if (checkout_fast_forward(head_commit->object.sha1, remoteheads->item->object.sha1))
                        return 1;
 
-               finish(o->sha1, msg.buf);
+               finish(head_commit, o->sha1, msg.buf);
                drop_save();
                return 0;
        } else if (!remoteheads->next && common->next)
@@ -1266,8 +1348,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                        git_committer_info(IDENT_ERROR_ON_NO_NAME);
                        printf(_("Trying really trivial in-index merge...\n"));
                        if (!read_tree_trivial(common->item->object.sha1,
-                                       head, remoteheads->item->object.sha1))
-                               return merge_trivial();
+                                       head_commit->object.sha1, remoteheads->item->object.sha1))
+                               return merge_trivial(head_commit);
                        printf(_("Nope.\n"));
                }
        } else {
@@ -1286,8 +1368,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                         * merge_bases again, otherwise "git merge HEAD^
                         * HEAD^^" would be missed.
                         */
-                       common_one = get_merge_bases(lookup_commit(head),
-                               j->item, 1);
+                       common_one = get_merge_bases(head_commit, j->item, 1);
                        if (hashcmp(common_one->item->object.sha1,
                                j->item->object.sha1)) {
                                up_to_date = 0;
@@ -1314,21 +1395,18 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
         * sync with the head commit.  The strategies are responsible
         * to ensure this.
         */
-       if (use_strategies_nr != 1) {
-               /*
-                * Stash away the local changes so that we can try more
-                * than one.
-                */
-               save_state();
-       } else {
-               memcpy(stash, null_sha1, 20);
-       }
+       if (use_strategies_nr == 1 ||
+           /*
+            * Stash away the local changes so that we can try more than one.
+            */
+           save_state(stash))
+               hashcpy(stash, null_sha1);
 
        for (i = 0; i < use_strategies_nr; i++) {
                int ret;
                if (i) {
                        printf(_("Rewinding the tree to pristine...\n"));
-                       restore_state();
+                       restore_state(head_commit->object.sha1, stash);
                }
                if (use_strategies_nr != 1)
                        printf(_("Trying merge strategy %s...\n"),
@@ -1340,7 +1418,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                wt_strategy = use_strategies[i]->name;
 
                ret = try_merge_strategy(use_strategies[i]->name,
-                       common, head_arg);
+                                        common, head_commit, head_arg);
                if (!option_commit && !ret) {
                        merge_was_ok = 1;
                        /*
@@ -1382,14 +1460,15 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
         * auto resolved the merge cleanly.
         */
        if (automerge_was_ok)
-               return finish_automerge(common, result_tree, wt_strategy);
+               return finish_automerge(head_commit, common, result_tree,
+                                       wt_strategy);
 
        /*
         * Pick the result from the best strategy and have the user fix
         * it up.
         */
        if (!best_strategy) {
-               restore_state();
+               restore_state(head_commit->object.sha1, stash);
                if (use_strategies_nr > 1)
                        fprintf(stderr,
                                _("No merge strategy handled the merge.\n"));
@@ -1401,41 +1480,16 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                ; /* We already have its result in the working tree. */
        else {
                printf(_("Rewinding the tree to pristine...\n"));
-               restore_state();
+               restore_state(head_commit->object.sha1, stash);
                printf(_("Using the %s to prepare resolving by hand.\n"),
                        best_strategy);
-               try_merge_strategy(best_strategy, common, head_arg);
+               try_merge_strategy(best_strategy, common, head_commit, head_arg);
        }
 
        if (squash)
-               finish(NULL, NULL);
-       else {
-               int fd;
-               struct commit_list *j;
-
-               for (j = remoteheads; j; j = j->next)
-                       strbuf_addf(&buf, "%s\n",
-                               sha1_to_hex(j->item->object.sha1));
-               fd = open(git_path("MERGE_HEAD"), O_WRONLY | O_CREAT, 0666);
-               if (fd < 0)
-                       die_errno(_("Could not open '%s' for writing"),
-                                 git_path("MERGE_HEAD"));
-               if (write_in_full(fd, buf.buf, buf.len) != buf.len)
-                       die_errno(_("Could not write to '%s'"), git_path("MERGE_HEAD"));
-               close(fd);
-               strbuf_addch(&merge_msg, '\n');
-               write_merge_msg();
-               fd = open(git_path("MERGE_MODE"), O_WRONLY | O_CREAT | O_TRUNC, 0666);
-               if (fd < 0)
-                       die_errno(_("Could not open '%s' for writing"),
-                                 git_path("MERGE_MODE"));
-               strbuf_reset(&buf);
-               if (!allow_fast_forward)
-                       strbuf_addf(&buf, "no-ff");
-               if (write_in_full(fd, buf.buf, buf.len) != buf.len)
-                       die_errno(_("Could not write to '%s'"), git_path("MERGE_MODE"));
-               close(fd);
-       }
+               finish(head_commit, NULL, NULL);
+       else
+               write_merge_state();
 
        if (merge_was_ok) {
                fprintf(stderr, _("Automatic merge went well; "