Merge branch 'rr/sequencer'

* rr/sequencer:
  sequencer: factor code out of revert builtin
  revert: prepare to move replay_action to header

Conflicts:
	builtin/revert.c

diff --cc sequencer.c
index d1f28a6945cbbdc8f58a32d7bb481ecd4af6cc39,54771196c37d32e78663322d98a4a32f6a947e28..5fcbcb8875454574f4d3a52b5d1ac84b99452ba7
--- 1/sequencer.c
--- 2/sequencer.c
+++ b/sequencer.c
@@@ -11,3 -24,906 +24,905 @@@ void remove_sequencer_state(void
        remove_dir_recursively(&seq_dir, 0);
        strbuf_release(&seq_dir);
  }
 -      if (show_hint) {
 -              advise("after resolving the conflicts, mark the corrected paths");
 -              advise("with 'git add <paths>' or 'git rm <paths>'");
 -              advise("and commit the result with 'git commit'");
 -      }
+ 
+ static const char *action_name(const struct replay_opts *opts)
+ {
+       return opts->action == REPLAY_REVERT ? "revert" : "cherry-pick";
+ }
+ 
+ static char *get_encoding(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(struct commit *commit, struct commit_message *out)
+ {
+       const char *encoding;
+       const char *abbrev, *subject;
+       int abbrev_len, subject_len;
+       char *q;
+ 
+       if (!commit->buffer)
+               return -1;
+       encoding = get_encoding(commit->buffer);
+       if (!encoding)
+               encoding = "UTF-8";
+       if (!git_commit_encoding)
+               git_commit_encoding = "UTF-8";
+ 
+       out->reencoded_message = NULL;
+       out->message = commit->buffer;
+       if (strcmp(encoding, git_commit_encoding))
+               out->reencoded_message = reencode_string(commit->buffer,
+                                       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);
+ 
+       subject_len = find_commit_subject(out->message, &subject);
+ 
+       out->parent_label = xmalloc(strlen("parent of ") + abbrev_len +
+                             strlen("... ") + subject_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, subject, subject_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)
+ {
+       const char *p = message, *eol;
+ 
+       while (*p && *p != '\n') {
+               for (eol = p + 1; *eol && *eol != '\n'; eol++)
+                       ; /* do nothing */
+               if (!prefixcmp(p, "encoding ")) {
+                       char *result = xmalloc(eol - 8 - p);
+                       strlcpy(result, p + 9, eol - 8 - p);
+                       return result;
+               }
+               p = eol;
+               if (*p == '\n')
+                       p++;
+       }
+       return NULL;
+ }
+ 
+ static void write_cherry_pick_head(struct commit *commit, const char *pseudoref)
+ {
+       const char *filename;
+       int fd;
+       struct strbuf buf = STRBUF_INIT;
+ 
+       strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
+ 
+       filename = git_path("%s", pseudoref);
+       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 || close(fd))
+               die_errno(_("Could not write to '%s'"), filename);
+       strbuf_release(&buf);
+ }
+ 
+ static void print_advice(int show_hint)
+ {
+       char *msg = getenv("GIT_CHERRY_PICK_HELP");
+ 
+       if (msg) {
+               fprintf(stderr, "%s\n", msg);
+               /*
+                * A conflict has occured but the porcelain
+                * (typically rebase --interactive) wants to take care
+                * of the commit itself so remove CHERRY_PICK_HEAD
+                */
+               unlink(git_path("CHERRY_PICK_HEAD"));
+               return;
+       }
+ 
++      if (show_hint)
++              advise(_("after resolving the conflicts, mark the corrected paths\n"
++                       "with 'git add <paths>' or 'git rm <paths>'\n"
++                       "and commit the result with 'git commit'"));
+ }
+ 
+ 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)
+ {
+       return lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
+ }
+ 
+ static int error_dirty_index(struct replay_opts *opts)
+ {
+       if (read_cache_unmerged())
+               return error_resolve_conflict(action_name(opts));
+ 
+       /* Different translation strings for cherry-pick and revert */
+       if (opts->action == REPLAY_PICK)
+               error(_("Your local changes would be overwritten by cherry-pick."));
+       else
+               error(_("Your local changes would be overwritten by revert."));
+ 
+       if (advice_commit_before_merge)
+               advise(_("Commit your changes or stash them to proceed."));
+       return -1;
+ }
+ 
+ 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 do_recursive_merge(struct commit *base, struct commit *next,
+                             const char *base_label, const char *next_label,
+                             unsigned char *head, struct strbuf *msgbuf,
+                             struct replay_opts *opts)
+ {
+       struct merge_options o;
+       struct tree *result, *next_tree, *base_tree, *head_tree;
+       int clean, index_fd;
+       const char **xopt;
+       static struct lock_file index_lock;
+ 
+       index_fd = hold_locked_index(&index_lock, 1);
+ 
+       read_cache();
+ 
+       init_merge_options(&o);
+       o.ancestor = base ? base_label : "(empty tree)";
+       o.branch1 = "HEAD";
+       o.branch2 = next ? next_label : "(empty tree)";
+ 
+       head_tree = parse_tree_indirect(head);
+       next_tree = next ? next->tree : empty_tree();
+       base_tree = base ? base->tree : empty_tree();
+ 
+       for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
+               parse_merge_opt(&o, *xopt);
+ 
+       clean = merge_trees(&o,
+                           head_tree,
+                           next_tree, base_tree, &result);
+ 
+       if (active_cache_changed &&
+           (write_cache(index_fd, active_cache, active_nr) ||
+            commit_locked_index(&index_lock)))
+               /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
+               die(_("%s: Unable to write new index file"), action_name(opts));
+       rollback_lock_file(&index_lock);
+ 
+       if (!clean) {
+               int i;
+               strbuf_addstr(msgbuf, "\nConflicts:\n\n");
+               for (i = 0; i < active_nr;) {
+                       struct cache_entry *ce = active_cache[i++];
+                       if (ce_stage(ce)) {
+                               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++;
+                       }
+               }
+       }
+ 
+       return !clean;
+ }
+ 
+ /*
+  * If we are cherry-pick, and if the merge did not result in
+  * hand-editing, we will hit this commit and inherit the original
+  * author date and name.
+  * If we are revert, or if our cherry-pick results in a hand merge,
+  * we had better say that the current user is responsible for that.
+  */
+ static int run_git_commit(const char *defmsg, struct replay_opts *opts)
+ {
+       /* 6 is max possible length of our args array including NULL */
+       const char *args[6];
+       int i = 0;
+ 
+       args[i++] = "commit";
+       args[i++] = "-n";
+       if (opts->signoff)
+               args[i++] = "-s";
+       if (!opts->edit) {
+               args[i++] = "-F";
+               args[i++] = defmsg;
+       }
+       args[i] = NULL;
+ 
+       return run_command_v_opt(args, RUN_GIT_CMD);
+ }
+ 
+ static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
+ {
+       unsigned char head[20];
+       struct commit *base, *next, *parent;
+       const char *base_label, *next_label;
+       struct commit_message msg = { NULL, NULL, NULL, NULL, NULL };
+       char *defmsg = NULL;
+       struct strbuf msgbuf = STRBUF_INIT;
+       int res;
+ 
+       if (opts->no_commit) {
+               /*
+                * We do not intend to commit immediately.  We just want to
+                * merge the differences in, so let's compute the tree
+                * that represents the "current" state for merge-recursive
+                * to work on.
+                */
+               if (write_cache_as_tree(head, 0, NULL))
+                       die (_("Your index file is unmerged."));
+       } else {
+               if (get_sha1("HEAD", head))
+                       return error(_("You do not have a valid HEAD"));
+               if (index_differs_from("HEAD", 0))
+                       return error_dirty_index(opts);
+       }
+       discard_cache();
+ 
+       if (!commit->parents) {
+               parent = NULL;
+       }
+       else if (commit->parents->next) {
+               /* Reverting or cherry-picking a merge commit */
+               int cnt;
+               struct commit_list *p;
+ 
+               if (!opts->mainline)
+                       return error(_("Commit %s is a merge but no -m option was given."),
+                               sha1_to_hex(commit->object.sha1));
+ 
+               for (cnt = 1, p = commit->parents;
+                    cnt != opts->mainline && p;
+                    cnt++)
+                       p = p->next;
+               if (cnt != opts->mainline || !p)
+                       return error(_("Commit %s does not have parent %d"),
+                               sha1_to_hex(commit->object.sha1), opts->mainline);
+               parent = p->item;
+       } else if (0 < opts->mainline)
+               return error(_("Mainline was specified but commit %s is not a merge."),
+                       sha1_to_hex(commit->object.sha1));
+       else
+               parent = commit->parents->item;
+ 
+       if (opts->allow_ff && parent && !hashcmp(parent->object.sha1, head))
+               return fast_forward_to(commit->object.sha1, head);
+ 
+       if (parent && parse_commit(parent) < 0)
+               /* TRANSLATORS: The first %s will be "revert" or
+                  "cherry-pick", the second %s a SHA1 */
+               return error(_("%s: cannot parse parent commit %s"),
+                       action_name(opts), sha1_to_hex(parent->object.sha1));
+ 
+       if (get_message(commit, &msg) != 0)
+               return error(_("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"
+        * on top of the current HEAD if we are cherry-pick.  Or the
+        * reverse of it if we are revert.
+        */
+ 
+       defmsg = git_pathdup("MERGE_MSG");
+ 
+       if (opts->action == REPLAY_REVERT) {
+               base = commit;
+               base_label = msg.label;
+               next = parent;
+               next_label = msg.parent_label;
+               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 && commit->parents->next) {
+                       strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
+                       strbuf_addstr(&msgbuf, sha1_to_hex(parent->object.sha1));
+               }
+               strbuf_addstr(&msgbuf, ".\n");
+       } else {
+               const char *p;
+ 
+               base = parent;
+               base_label = msg.parent_label;
+               next = commit;
+               next_label = msg.label;
+ 
+               /*
+                * Append the commit log message to msgbuf; it starts
+                * after the tree, parent, author, committer
+                * information followed by "\n\n".
+                */
+               p = strstr(msg.message, "\n\n");
+               if (p) {
+                       p += 2;
+                       strbuf_addstr(&msgbuf, p);
+               }
+ 
+               if (opts->record_origin) {
+                       strbuf_addstr(&msgbuf, "(cherry picked from commit ");
+                       strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
+                       strbuf_addstr(&msgbuf, ")\n");
+               }
+       }
+ 
+       if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REPLAY_REVERT) {
+               res = do_recursive_merge(base, next, base_label, next_label,
+                                        head, &msgbuf, opts);
+               write_message(&msgbuf, defmsg);
+       } else {
+               struct commit_list *common = NULL;
+               struct commit_list *remotes = NULL;
+ 
+               write_message(&msgbuf, defmsg);
+ 
+               commit_list_insert(base, &common);
+               commit_list_insert(next, &remotes);
+               res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
+                                       common, sha1_to_hex(head), remotes);
+               free_commit_list(common);
+               free_commit_list(remotes);
+       }
+ 
+       /*
+        * If the merge was clean or if it failed due to conflict, we write
+        * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
+        * However, if the merge did not even start, then we don't want to
+        * write it at all.
+        */
+       if (opts->action == REPLAY_PICK && !opts->no_commit && (res == 0 || res == 1))
+               write_cherry_pick_head(commit, "CHERRY_PICK_HEAD");
+       if (opts->action == REPLAY_REVERT && ((opts->no_commit && res == 0) || res == 1))
+               write_cherry_pick_head(commit, "REVERT_HEAD");
+ 
+       if (res) {
+               error(opts->action == REPLAY_REVERT
+                     ? _("could not revert %s... %s")
+                     : _("could not apply %s... %s"),
+                     find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV),
+                     msg.subject);
+               print_advice(res == 1);
+               rerere(opts->allow_rerere_auto);
+       } else {
+               if (!opts->no_commit)
+                       res = run_git_commit(defmsg, opts);
+       }
+ 
+       free_message(&msg);
+       free(defmsg);
+ 
+       return res;
+ }
+ 
+ static void prepare_revs(struct replay_opts *opts)
+ {
+       if (opts->action != REPLAY_REVERT)
+               opts->revs->reverse ^= 1;
+ 
+       if (prepare_revision_walk(opts->revs))
+               die(_("revision walk setup failed"));
+ 
+       if (!opts->revs->commits)
+               die(_("empty commit set passed"));
+ }
+ 
+ static void read_and_refresh_cache(struct replay_opts *opts)
+ {
+       static struct lock_file index_lock;
+       int index_fd = hold_locked_index(&index_lock, 0);
+       if (read_index_preload(&the_index, NULL) < 0)
+               die(_("git %s: failed to read the index"), action_name(opts));
+       refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
+       if (the_index.cache_changed) {
+               if (write_index(&the_index, index_fd) ||
+                   commit_locked_index(&index_lock))
+                       die(_("git %s: failed to refresh the index"), action_name(opts));
+       }
+       rollback_lock_file(&index_lock);
+ }
+ 
+ /*
+  * Append a commit to the end of the commit_list.
+  *
+  * next starts by pointing to the variable that holds the head of an
+  * empty commit_list, and is updated to point to the "next" field of
+  * the last item on the list as new commits are appended.
+  *
+  * Usage example:
+  *
+  *     struct commit_list *list;
+  *     struct commit_list **next = &list;
+  *
+  *     next = commit_list_append(c1, next);
+  *     next = commit_list_append(c2, next);
+  *     assert(commit_list_count(list) == 2);
+  *     return list;
+  */
+ static struct commit_list **commit_list_append(struct commit *commit,
+                                              struct commit_list **next)
+ {
+       struct commit_list *new = xmalloc(sizeof(struct commit_list));
+       new->item = commit;
+       *next = new;
+       new->next = NULL;
+       return &new->next;
+ }
+ 
+ static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
+               struct replay_opts *opts)
+ {
+       struct commit_list *cur = NULL;
+       const char *sha1_abbrev = NULL;
+       const char *action_str = opts->action == REPLAY_REVERT ? "revert" : "pick";
+       const char *subject;
+       int subject_len;
+ 
+       for (cur = todo_list; cur; cur = cur->next) {
+               sha1_abbrev = find_unique_abbrev(cur->item->object.sha1, DEFAULT_ABBREV);
+               subject_len = find_commit_subject(cur->item->buffer, &subject);
+               strbuf_addf(buf, "%s %s %.*s\n", action_str, sha1_abbrev,
+                       subject_len, subject);
+       }
+       return 0;
+ }
+ 
+ static struct commit *parse_insn_line(char *bol, char *eol, struct replay_opts *opts)
+ {
+       unsigned char commit_sha1[20];
+       enum replay_action action;
+       char *end_of_object_name;
+       int saved, status, padding;
+ 
+       if (!prefixcmp(bol, "pick")) {
+               action = REPLAY_PICK;
+               bol += strlen("pick");
+       } else if (!prefixcmp(bol, "revert")) {
+               action = REPLAY_REVERT;
+               bol += strlen("revert");
+       } else
+               return NULL;
+ 
+       /* Eat up extra spaces/ tabs before object name */
+       padding = strspn(bol, " \t");
+       if (!padding)
+               return NULL;
+       bol += padding;
+ 
+       end_of_object_name = bol + strcspn(bol, " \t\n");
+       saved = *end_of_object_name;
+       *end_of_object_name = '\0';
+       status = get_sha1(bol, commit_sha1);
+       *end_of_object_name = saved;
+ 
+       /*
+        * Verify that the action matches up with the one in
+        * opts; we don't support arbitrary instructions
+        */
+       if (action != opts->action) {
+               const char *action_str;
+               action_str = action == REPLAY_REVERT ? "revert" : "cherry-pick";
+               error(_("Cannot %s during a %s"), action_str, action_name(opts));
+               return NULL;
+       }
+ 
+       if (status < 0)
+               return NULL;
+ 
+       return lookup_commit_reference(commit_sha1);
+ }
+ 
+ static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
+                       struct replay_opts *opts)
+ {
+       struct commit_list **next = todo_list;
+       struct commit *commit;
+       char *p = buf;
+       int i;
+ 
+       for (i = 1; *p; i++) {
+               char *eol = strchrnul(p, '\n');
+               commit = parse_insn_line(p, eol, opts);
+               if (!commit)
+                       return error(_("Could not parse line %d."), i);
+               next = commit_list_append(commit, next);
+               p = *eol ? eol + 1 : eol;
+       }
+       if (!*todo_list)
+               return error(_("No commits parsed."));
+       return 0;
+ }
+ 
+ static void read_populate_todo(struct commit_list **todo_list,
+                       struct replay_opts *opts)
+ {
+       const char *todo_file = git_path(SEQ_TODO_FILE);
+       struct strbuf buf = STRBUF_INIT;
+       int fd, res;
+ 
+       fd = open(todo_file, O_RDONLY);
+       if (fd < 0)
+               die_errno(_("Could not open %s"), todo_file);
+       if (strbuf_read(&buf, fd, 0) < 0) {
+               close(fd);
+               strbuf_release(&buf);
+               die(_("Could not read %s."), todo_file);
+       }
+       close(fd);
+ 
+       res = parse_insn_buffer(buf.buf, todo_list, opts);
+       strbuf_release(&buf);
+       if (res)
+               die(_("Unusable instruction sheet: %s"), todo_file);
+ }
+ 
+ static int populate_opts_cb(const char *key, const char *value, void *data)
+ {
+       struct replay_opts *opts = data;
+       int error_flag = 1;
+ 
+       if (!value)
+               error_flag = 0;
+       else if (!strcmp(key, "options.no-commit"))
+               opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.edit"))
+               opts->edit = git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.signoff"))
+               opts->signoff = git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.record-origin"))
+               opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.allow-ff"))
+               opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
+       else if (!strcmp(key, "options.mainline"))
+               opts->mainline = git_config_int(key, value);
+       else if (!strcmp(key, "options.strategy"))
+               git_config_string(&opts->strategy, key, value);
+       else if (!strcmp(key, "options.strategy-option")) {
+               ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
+               opts->xopts[opts->xopts_nr++] = xstrdup(value);
+       } else
+               return error(_("Invalid key: %s"), key);
+ 
+       if (!error_flag)
+               return error(_("Invalid value for %s: %s"), key, value);
+ 
+       return 0;
+ }
+ 
+ static void read_populate_opts(struct replay_opts **opts_ptr)
+ {
+       const char *opts_file = git_path(SEQ_OPTS_FILE);
+ 
+       if (!file_exists(opts_file))
+               return;
+       if (git_config_from_file(populate_opts_cb, opts_file, *opts_ptr) < 0)
+               die(_("Malformed options sheet: %s"), opts_file);
+ }
+ 
+ static void walk_revs_populate_todo(struct commit_list **todo_list,
+                               struct replay_opts *opts)
+ {
+       struct commit *commit;
+       struct commit_list **next;
+ 
+       prepare_revs(opts);
+ 
+       next = todo_list;
+       while ((commit = get_revision(opts->revs)))
+               next = commit_list_append(commit, next);
+ }
+ 
+ static int create_seq_dir(void)
+ {
+       const char *seq_dir = git_path(SEQ_DIR);
+ 
+       if (file_exists(seq_dir)) {
+               error(_("a cherry-pick or revert is already in progress"));
+               advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
+               return -1;
+       }
+       else if (mkdir(seq_dir, 0777) < 0)
+               die_errno(_("Could not create sequencer directory %s"), seq_dir);
+       return 0;
+ }
+ 
+ static void save_head(const char *head)
+ {
+       const char *head_file = git_path(SEQ_HEAD_FILE);
+       static struct lock_file head_lock;
+       struct strbuf buf = STRBUF_INIT;
+       int fd;
+ 
+       fd = hold_lock_file_for_update(&head_lock, head_file, LOCK_DIE_ON_ERROR);
+       strbuf_addf(&buf, "%s\n", head);
+       if (write_in_full(fd, buf.buf, buf.len) < 0)
+               die_errno(_("Could not write to %s"), head_file);
+       if (commit_lock_file(&head_lock) < 0)
+               die(_("Error wrapping up %s."), head_file);
+ }
+ 
+ static int reset_for_rollback(const unsigned char *sha1)
+ {
+       const char *argv[4];    /* reset --merge <arg> + NULL */
+       argv[0] = "reset";
+       argv[1] = "--merge";
+       argv[2] = sha1_to_hex(sha1);
+       argv[3] = NULL;
+       return run_command_v_opt(argv, RUN_GIT_CMD);
+ }
+ 
+ static int rollback_single_pick(void)
+ {
+       unsigned char head_sha1[20];
+ 
+       if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
+           !file_exists(git_path("REVERT_HEAD")))
+               return error(_("no cherry-pick or revert in progress"));
+       if (read_ref_full("HEAD", head_sha1, 0, NULL))
+               return error(_("cannot resolve HEAD"));
+       if (is_null_sha1(head_sha1))
+               return error(_("cannot abort from a branch yet to be born"));
+       return reset_for_rollback(head_sha1);
+ }
+ 
+ static int sequencer_rollback(struct replay_opts *opts)
+ {
+       const char *filename;
+       FILE *f;
+       unsigned char sha1[20];
+       struct strbuf buf = STRBUF_INIT;
+ 
+       filename = git_path(SEQ_HEAD_FILE);
+       f = fopen(filename, "r");
+       if (!f && errno == ENOENT) {
+               /*
+                * There is no multiple-cherry-pick in progress.
+                * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
+                * a single-cherry-pick in progress, abort that.
+                */
+               return rollback_single_pick();
+       }
+       if (!f)
+               return error(_("cannot open %s: %s"), filename,
+                                               strerror(errno));
+       if (strbuf_getline(&buf, f, '\n')) {
+               error(_("cannot read %s: %s"), filename, ferror(f) ?
+                       strerror(errno) : _("unexpected end of file"));
+               fclose(f);
+               goto fail;
+       }
+       fclose(f);
+       if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
+               error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
+                       filename);
+               goto fail;
+       }
+       if (reset_for_rollback(sha1))
+               goto fail;
+       remove_sequencer_state();
+       strbuf_release(&buf);
+       return 0;
+ fail:
+       strbuf_release(&buf);
+       return -1;
+ }
+ 
+ static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
+ {
+       const char *todo_file = git_path(SEQ_TODO_FILE);
+       static struct lock_file todo_lock;
+       struct strbuf buf = STRBUF_INIT;
+       int fd;
+ 
+       fd = hold_lock_file_for_update(&todo_lock, todo_file, LOCK_DIE_ON_ERROR);
+       if (format_todo(&buf, todo_list, opts) < 0)
+               die(_("Could not format %s."), todo_file);
+       if (write_in_full(fd, buf.buf, buf.len) < 0) {
+               strbuf_release(&buf);
+               die_errno(_("Could not write to %s"), todo_file);
+       }
+       if (commit_lock_file(&todo_lock) < 0) {
+               strbuf_release(&buf);
+               die(_("Error wrapping up %s."), todo_file);
+       }
+       strbuf_release(&buf);
+ }
+ 
+ static void save_opts(struct replay_opts *opts)
+ {
+       const char *opts_file = git_path(SEQ_OPTS_FILE);
+ 
+       if (opts->no_commit)
+               git_config_set_in_file(opts_file, "options.no-commit", "true");
+       if (opts->edit)
+               git_config_set_in_file(opts_file, "options.edit", "true");
+       if (opts->signoff)
+               git_config_set_in_file(opts_file, "options.signoff", "true");
+       if (opts->record_origin)
+               git_config_set_in_file(opts_file, "options.record-origin", "true");
+       if (opts->allow_ff)
+               git_config_set_in_file(opts_file, "options.allow-ff", "true");
+       if (opts->mainline) {
+               struct strbuf buf = STRBUF_INIT;
+               strbuf_addf(&buf, "%d", opts->mainline);
+               git_config_set_in_file(opts_file, "options.mainline", buf.buf);
+               strbuf_release(&buf);
+       }
+       if (opts->strategy)
+               git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
+       if (opts->xopts) {
+               int i;
+               for (i = 0; i < opts->xopts_nr; i++)
+                       git_config_set_multivar_in_file(opts_file,
+                                                       "options.strategy-option",
+                                                       opts->xopts[i], "^$", 0);
+       }
+ }
+ 
+ static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
+ {
+       struct commit_list *cur;
+       int res;
+ 
+       setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
+       if (opts->allow_ff)
+               assert(!(opts->signoff || opts->no_commit ||
+                               opts->record_origin || opts->edit));
+       read_and_refresh_cache(opts);
+ 
+       for (cur = todo_list; cur; cur = cur->next) {
+               save_todo(cur, opts);
+               res = do_pick_commit(cur->item, opts);
+               if (res)
+                       return res;
+       }
+ 
+       /*
+        * Sequence of picks finished successfully; cleanup by
+        * removing the .git/sequencer directory
+        */
+       remove_sequencer_state();
+       return 0;
+ }
+ 
+ static int continue_single_pick(void)
+ {
+       const char *argv[] = { "commit", NULL };
+ 
+       if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
+           !file_exists(git_path("REVERT_HEAD")))
+               return error(_("no cherry-pick or revert in progress"));
+       return run_command_v_opt(argv, RUN_GIT_CMD);
+ }
+ 
+ static int sequencer_continue(struct replay_opts *opts)
+ {
+       struct commit_list *todo_list = NULL;
+ 
+       if (!file_exists(git_path(SEQ_TODO_FILE)))
+               return continue_single_pick();
+       read_populate_opts(&opts);
+       read_populate_todo(&todo_list, opts);
+ 
+       /* Verify that the conflict has been resolved */
+       if (file_exists(git_path("CHERRY_PICK_HEAD")) ||
+           file_exists(git_path("REVERT_HEAD"))) {
+               int ret = continue_single_pick();
+               if (ret)
+                       return ret;
+       }
+       if (index_differs_from("HEAD", 0))
+               return error_dirty_index(opts);
+       todo_list = todo_list->next;
+       return pick_commits(todo_list, opts);
+ }
+ 
+ static int single_pick(struct commit *cmit, struct replay_opts *opts)
+ {
+       setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
+       return do_pick_commit(cmit, opts);
+ }
+ 
+ int sequencer_pick_revisions(struct replay_opts *opts)
+ {
+       struct commit_list *todo_list = NULL;
+       unsigned char sha1[20];
+ 
+       if (opts->subcommand == REPLAY_NONE)
+               assert(opts->revs);
+ 
+       read_and_refresh_cache(opts);
+ 
+       /*
+        * Decide what to do depending on the arguments; a fresh
+        * cherry-pick should be handled differently from an existing
+        * one that is being continued
+        */
+       if (opts->subcommand == REPLAY_REMOVE_STATE) {
+               remove_sequencer_state();
+               return 0;
+       }
+       if (opts->subcommand == REPLAY_ROLLBACK)
+               return sequencer_rollback(opts);
+       if (opts->subcommand == REPLAY_CONTINUE)
+               return sequencer_continue(opts);
+ 
+       /*
+        * If we were called as "git cherry-pick <commit>", just
+        * cherry-pick/revert it, set CHERRY_PICK_HEAD /
+        * REVERT_HEAD, and don't touch the sequencer state.
+        * This means it is possible to cherry-pick in the middle
+        * of a cherry-pick sequence.
+        */
+       if (opts->revs->cmdline.nr == 1 &&
+           opts->revs->cmdline.rev->whence == REV_CMD_REV &&
+           opts->revs->no_walk &&
+           !opts->revs->cmdline.rev->flags) {
+               struct commit *cmit;
+               if (prepare_revision_walk(opts->revs))
+                       die(_("revision walk setup failed"));
+               cmit = get_revision(opts->revs);
+               if (!cmit || get_revision(opts->revs))
+                       die("BUG: expected exactly one commit from walk");
+               return single_pick(cmit, opts);
+       }
+ 
+       /*
+        * Start a new cherry-pick/ revert sequence; but
+        * first, make sure that an existing one isn't in
+        * progress
+        */
+ 
+       walk_revs_populate_todo(&todo_list, opts);
+       if (create_seq_dir() < 0)
+               return -1;
+       if (get_sha1("HEAD", sha1)) {
+               if (opts->action == REPLAY_REVERT)
+                       return error(_("Can't revert as initial commit"));
+               return error(_("Can't cherry-pick into empty head"));
+       }
+       save_head(sha1_to_hex(sha1));
+       save_opts(opts);
+       return pick_commits(todo_list, opts);
+ }