push: require force for refs under refs/tags/
[gitweb.git] / commit.c
index 4c5aac8765a541e92b3de25c2118908221e55c6f..e8eb0aec5509a4fd09698bd15a37d1f4e8341f5e 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -1,57 +1,20 @@
 #include "cache.h"
 #include "tag.h"
 #include "commit.h"
+#include "pkt-line.h"
+#include "utf8.h"
+#include "diff.h"
+#include "revision.h"
+#include "notes.h"
+#include "gpg-interface.h"
+#include "mergesort.h"
 
-int save_commit_buffer = 1;
-
-struct sort_node
-{
-       /*
-         * the number of children of the associated commit
-         * that also occur in the list being sorted.
-         */
-       unsigned int indegree;
+static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
 
-       /*
-         * reference to original list item that we will re-use
-         * on output.
-         */
-       struct commit_list * list_item;
-
-};
+int save_commit_buffer = 1;
 
 const char *commit_type = "commit";
 
-struct cmt_fmt_map {
-       const char *n;
-       size_t cmp_len;
-       enum cmit_fmt v;
-} cmt_fmts[] = {
-       { "raw",        1,      CMIT_FMT_RAW },
-       { "medium",     1,      CMIT_FMT_MEDIUM },
-       { "short",      1,      CMIT_FMT_SHORT },
-       { "email",      1,      CMIT_FMT_EMAIL },
-       { "full",       5,      CMIT_FMT_FULL },
-       { "fuller",     5,      CMIT_FMT_FULLER },
-       { "oneline",    1,      CMIT_FMT_ONELINE },
-};
-
-enum cmit_fmt get_commit_format(const char *arg)
-{
-       int i;
-
-       if (!arg || !*arg)
-               return CMIT_FMT_DEFAULT;
-       if (*arg == '=')
-               arg++;
-       for (i = 0; i < ARRAY_SIZE(cmt_fmts); i++) {
-               if (!strncmp(arg, cmt_fmts[i].n, cmt_fmts[i].cmp_len))
-                       return cmt_fmts[i].v;
-       }
-
-       die("invalid --pretty format: %s", arg);
-}
-
 static struct commit *check_commit(struct object *obj,
                                   const unsigned char *sha1,
                                   int quiet)
@@ -80,36 +43,66 @@ struct commit *lookup_commit_reference(const unsigned char *sha1)
        return lookup_commit_reference_gently(sha1, 0);
 }
 
+struct commit *lookup_commit_or_die(const unsigned char *sha1, const char *ref_name)
+{
+       struct commit *c = lookup_commit_reference(sha1);
+       if (!c)
+               die(_("could not parse %s"), ref_name);
+       if (hashcmp(sha1, c->object.sha1)) {
+               warning(_("%s %s is not a commit!"),
+                       ref_name, sha1_to_hex(sha1));
+       }
+       return c;
+}
+
 struct commit *lookup_commit(const unsigned char *sha1)
 {
        struct object *obj = lookup_object(sha1);
-       if (!obj) {
-               struct commit *ret = alloc_commit_node();
-               created_object(sha1, &ret->object);
-               ret->object.type = OBJ_COMMIT;
-               return ret;
-       }
+       if (!obj)
+               return create_object(sha1, OBJ_COMMIT, alloc_commit_node());
        if (!obj->type)
                obj->type = OBJ_COMMIT;
        return check_commit(obj, sha1, 0);
 }
 
-static unsigned long parse_commit_date(const char *buf)
+struct commit *lookup_commit_reference_by_name(const char *name)
+{
+       unsigned char sha1[20];
+       struct commit *commit;
+
+       if (get_sha1_committish(name, sha1))
+               return NULL;
+       commit = lookup_commit_reference(sha1);
+       if (!commit || parse_commit(commit))
+               return NULL;
+       return commit;
+}
+
+static unsigned long parse_commit_date(const char *buf, const char *tail)
 {
-       unsigned long date;
+       const char *dateptr;
 
+       if (buf + 6 >= tail)
+               return 0;
        if (memcmp(buf, "author", 6))
                return 0;
-       while (*buf++ != '\n')
+       while (buf < tail && *buf++ != '\n')
                /* nada */;
+       if (buf + 9 >= tail)
+               return 0;
        if (memcmp(buf, "committer", 9))
                return 0;
-       while (*buf++ != '>')
+       while (buf < tail && *buf++ != '>')
+               /* nada */;
+       if (buf >= tail)
+               return 0;
+       dateptr = buf;
+       while (buf < tail && *buf++ != '\n')
                /* nada */;
-       date = strtoul(buf, NULL, 10);
-       if (date == ULONG_MAX)
-               date = 0;
-       return date;
+       if (buf >= tail)
+               return 0;
+       /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
+       return strtoul(dateptr, NULL, 10);
 }
 
 static struct commit_graft **commit_graft;
@@ -123,7 +116,7 @@ static int commit_graft_pos(const unsigned char *sha1)
        while (lo < hi) {
                int mi = (lo + hi) / 2;
                struct commit_graft *graft = commit_graft[mi];
-               int cmp = memcmp(sha1, graft->sha1, 20);
+               int cmp = hashcmp(sha1, graft->sha1);
                if (!cmp)
                        return mi;
                if (cmp < 0)
@@ -137,7 +130,7 @@ static int commit_graft_pos(const unsigned char *sha1)
 int register_commit_graft(struct commit_graft *graft, int ignore_dups)
 {
        int pos = commit_graft_pos(graft->sha1);
-       
+
        if (0 <= pos) {
                if (ignore_dups)
                        free(graft);
@@ -169,16 +162,12 @@ struct commit_graft *read_graft_line(char *buf, int len)
        int i;
        struct commit_graft *graft = NULL;
 
-       if (buf[len-1] == '\n')
-               buf[--len] = 0;
+       while (len && isspace(buf[len-1]))
+               buf[--len] = '\0';
        if (buf[0] == '#' || buf[0] == '\0')
                return NULL;
-       if ((len + 1) % 41) {
-       bad_graft_data:
-               error("bad graft data: %s", buf);
-               free(graft);
-               return NULL;
-       }
+       if ((len + 1) % 41)
+               goto bad_graft_data;
        i = (len + 1) / 41 - 1;
        graft = xmalloc(sizeof(*graft) + 20 * i);
        graft->nr_parent = i;
@@ -191,9 +180,14 @@ struct commit_graft *read_graft_line(char *buf, int len)
                        goto bad_graft_data;
        }
        return graft;
+
+bad_graft_data:
+       error("bad graft data: %s", buf);
+       free(graft);
+       return NULL;
 }
 
-int read_graft_file(const char *graft_file)
+static int read_graft_file(const char *graft_file)
 {
        FILE *fp = fopen(graft_file, "r");
        char buf[1024];
@@ -221,10 +215,12 @@ static void prepare_commit_graft(void)
                return;
        graft_file = get_graft_file();
        read_graft_file(graft_file);
+       /* make sure shallows are read */
+       is_repository_shallow();
        commit_graft_prepared = 1;
 }
 
-static struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
+struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
 {
        int pos;
        prepare_commit_graft();
@@ -234,27 +230,45 @@ static struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
        return commit_graft[pos];
 }
 
-int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
+int for_each_commit_graft(each_commit_graft_fn fn, void *cb_data)
+{
+       int i, ret;
+       for (i = ret = 0; i < commit_graft_nr && !ret; i++)
+               ret = fn(commit_graft[i], cb_data);
+       return ret;
+}
+
+int unregister_shallow(const unsigned char *sha1)
 {
-       char *tail = buffer;
-       char *bufptr = buffer;
+       int pos = commit_graft_pos(sha1);
+       if (pos < 0)
+               return -1;
+       if (pos + 1 < commit_graft_nr)
+               memmove(commit_graft + pos, commit_graft + pos + 1,
+                               sizeof(struct commit_graft *)
+                               * (commit_graft_nr - pos - 1));
+       commit_graft_nr--;
+       return 0;
+}
+
+int parse_commit_buffer(struct commit *item, const void *buffer, unsigned long size)
+{
+       const char *tail = buffer;
+       const char *bufptr = buffer;
        unsigned char parent[20];
        struct commit_list **pptr;
        struct commit_graft *graft;
-       unsigned n_refs = 0;
 
        if (item->object.parsed)
                return 0;
        item->object.parsed = 1;
        tail += size;
-       if (tail <= bufptr + 5 || memcmp(bufptr, "tree ", 5))
+       if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
                return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
-       if (tail <= bufptr + 45 || get_sha1_hex(bufptr + 5, parent) < 0)
+       if (get_sha1_hex(bufptr + 5, parent) < 0)
                return error("bad tree pointer in commit %s",
                             sha1_to_hex(item->object.sha1));
        item->tree = lookup_tree(parent);
-       if (item->tree)
-               n_refs++;
        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
        pptr = &item->parents;
 
@@ -267,13 +281,15 @@ int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
                    bufptr[47] != '\n')
                        return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
                bufptr += 48;
-               if (graft)
+               /*
+                * The clone is shallow if nr_parent < 0, and we must
+                * not traverse its real parents even when we unhide them.
+                */
+               if (graft && (graft->nr_parent < 0 || grafts_replace_parents))
                        continue;
                new_parent = lookup_commit(parent);
-               if (new_parent) {
+               if (new_parent)
                        pptr = &commit_list_insert(new_parent, pptr)->next;
-                       n_refs++;
-               }
        }
        if (graft) {
                int i;
@@ -283,39 +299,29 @@ int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
                        if (!new_parent)
                                continue;
                        pptr = &commit_list_insert(new_parent, pptr)->next;
-                       n_refs++;
                }
        }
-       item->date = parse_commit_date(bufptr);
-
-       if (track_object_refs) {
-               unsigned i = 0;
-               struct commit_list *p;
-               struct object_refs *refs = alloc_object_refs(n_refs);
-               if (item->tree)
-                       refs->ref[i++] = &item->tree->object;
-               for (p = item->parents; p; p = p->next)
-                       refs->ref[i++] = &p->item->object;
-               set_object_refs(&item->object, refs);
-       }
+       item->date = parse_commit_date(bufptr, tail);
 
        return 0;
 }
 
 int parse_commit(struct commit *item)
 {
-       char type[20];
+       enum object_type type;
        void *buffer;
        unsigned long size;
        int ret;
 
+       if (!item)
+               return -1;
        if (item->object.parsed)
                return 0;
-       buffer = read_sha1_file(item->object.sha1, type, &size);
+       buffer = read_sha1_file(item->object.sha1, &type, &size);
        if (!buffer)
                return error("Could not read %s",
                             sha1_to_hex(item->object.sha1));
-       if (strcmp(type, commit_type)) {
+       if (type != OBJ_COMMIT) {
                free(buffer);
                return error("Object %s not a commit",
                             sha1_to_hex(item->object.sha1));
@@ -329,6 +335,25 @@ int parse_commit(struct commit *item)
        return ret;
 }
 
+int find_commit_subject(const char *commit_buffer, const char **subject)
+{
+       const char *eol;
+       const char *p = commit_buffer;
+
+       while (*p && (*p != '\n' || p[1] != '\n'))
+               p++;
+       if (*p) {
+               p += 2;
+               for (eol = p; *eol && *eol != '\n'; eol++)
+                       ; /* do nothing */
+       } else
+               eol = p;
+
+       *subject = p;
+
+       return eol - p;
+}
+
 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 {
        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
@@ -338,6 +363,14 @@ struct commit_list *commit_list_insert(struct commit *item, struct commit_list *
        return new_list;
 }
 
+unsigned commit_list_count(const struct commit_list *l)
+{
+       unsigned c = 0;
+       for (; l; l = l->next )
+               c++;
+       return c;
+}
+
 void free_commit_list(struct commit_list *list)
 {
        while (list) {
@@ -347,7 +380,7 @@ void free_commit_list(struct commit_list *list)
        }
 }
 
-struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
+struct commit_list * commit_list_insert_by_date(struct commit *item, struct commit_list **list)
 {
        struct commit_list **pp = list;
        struct commit_list *p;
@@ -360,15 +393,31 @@ struct commit_list * insert_by_date(struct commit *item, struct commit_list **li
        return commit_list_insert(item, pp);
 }
 
-       
-void sort_by_date(struct commit_list **list)
+static int commit_list_compare_by_date(const void *a, const void *b)
 {
-       struct commit_list *ret = NULL;
-       while (*list) {
-               insert_by_date((*list)->item, &ret);
-               *list = (*list)->next;
-       }
-       *list = ret;
+       unsigned long a_date = ((const struct commit_list *)a)->item->date;
+       unsigned long b_date = ((const struct commit_list *)b)->item->date;
+       if (a_date < b_date)
+               return 1;
+       if (a_date > b_date)
+               return -1;
+       return 0;
+}
+
+static void *commit_list_get_next(const void *a)
+{
+       return ((const struct commit_list *)a)->next;
+}
+
+static void commit_list_set_next(void *a, void *next)
+{
+       ((struct commit_list *)a)->next = next;
+}
+
+void commit_list_sort_by_date(struct commit_list **list)
+{
+       *list = llist_mergesort(*list, commit_list_get_next, commit_list_set_next,
+                               commit_list_compare_by_date);
 }
 
 struct commit *pop_most_recent_commit(struct commit_list **list,
@@ -383,327 +432,57 @@ struct commit *pop_most_recent_commit(struct commit_list **list,
 
        while (parents) {
                struct commit *commit = parents->item;
-               parse_commit(commit);
-               if (!(commit->object.flags & mark)) {
+               if (!parse_commit(commit) && !(commit->object.flags & mark)) {
                        commit->object.flags |= mark;
-                       insert_by_date(commit, list);
+                       commit_list_insert_by_date(commit, list);
                }
                parents = parents->next;
        }
        return ret;
 }
 
-void clear_commit_marks(struct commit *commit, unsigned int mark)
-{
-       struct commit_list *parents;
-
-       commit->object.flags &= ~mark;
-       parents = commit->parents;
-       while (parents) {
-               struct commit *parent = parents->item;
-
-               /* Have we already cleared this? */
-               if (mark & parent->object.flags)
-                       clear_commit_marks(parent, mark);
-               parents = parents->next;
-       }
-}
-
-/*
- * Generic support for pretty-printing the header
- */
-static int get_one_line(const char *msg, unsigned long len)
-{
-       int ret = 0;
-
-       while (len--) {
-               char c = *msg++;
-               if (!c)
-                       break;
-               ret++;
-               if (c == '\n')
-                       break;
-       }
-       return ret;
-}
-
-static int is_rfc2047_special(char ch)
+static void clear_commit_marks_1(struct commit_list **plist,
+                                struct commit *commit, unsigned int mark)
 {
-       return ((ch & 0x80) || (ch == '=') || (ch == '?') || (ch == '_'));
-}
+       while (commit) {
+               struct commit_list *parents;
 
-static int add_rfc2047(char *buf, const char *line, int len)
-{
-       char *bp = buf;
-       int i, needquote;
-       static const char q_utf8[] = "=?utf-8?q?";
+               if (!(mark & commit->object.flags))
+                       return;
 
-       for (i = needquote = 0; !needquote && i < len; i++) {
-               unsigned ch = line[i];
-               if (ch & 0x80)
-                       needquote++;
-               if ((i + 1 < len) &&
-                   (ch == '=' && line[i+1] == '?'))
-                       needquote++;
-       }
-       if (!needquote)
-               return sprintf(buf, "%.*s", len, line);
+               commit->object.flags &= ~mark;
 
-       memcpy(bp, q_utf8, sizeof(q_utf8)-1);
-       bp += sizeof(q_utf8)-1;
-       for (i = 0; i < len; i++) {
-               unsigned ch = line[i] & 0xFF;
-               if (is_rfc2047_special(ch)) {
-                       sprintf(bp, "=%02X", ch);
-                       bp += 3;
-               }
-               else if (ch == ' ')
-                       *bp++ = '_';
-               else
-                       *bp++ = ch;
-       }
-       memcpy(bp, "?=", 2);
-       bp += 2;
-       return bp - buf;
-}
+               parents = commit->parents;
+               if (!parents)
+                       return;
 
-static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf, const char *line)
-{
-       char *date;
-       int namelen;
-       unsigned long time;
-       int tz, ret;
-       const char *filler = "    ";
+               while ((parents = parents->next))
+                       commit_list_insert(parents->item, plist);
 
-       if (fmt == CMIT_FMT_ONELINE)
-               return 0;
-       date = strchr(line, '>');
-       if (!date)
-               return 0;
-       namelen = ++date - line;
-       time = strtoul(date, &date, 10);
-       tz = strtol(date, NULL, 10);
-
-       if (fmt == CMIT_FMT_EMAIL) {
-               char *name_tail = strchr(line, '<');
-               int display_name_length;
-               if (!name_tail)
-                       return 0;
-               while (line < name_tail && isspace(name_tail[-1]))
-                       name_tail--;
-               display_name_length = name_tail - line;
-               filler = "";
-               strcpy(buf, "From: ");
-               ret = strlen(buf);
-               ret += add_rfc2047(buf + ret, line, display_name_length);
-               memcpy(buf + ret, name_tail, namelen - display_name_length);
-               ret += namelen - display_name_length;
-               buf[ret++] = '\n';
-       }
-       else {
-               ret = sprintf(buf, "%s: %.*s%.*s\n", what,
-                             (fmt == CMIT_FMT_FULLER) ? 4 : 0,
-                             filler, namelen, line);
-       }
-       switch (fmt) {
-       case CMIT_FMT_MEDIUM:
-               ret += sprintf(buf + ret, "Date:   %s\n", show_date(time, tz));
-               break;
-       case CMIT_FMT_EMAIL:
-               ret += sprintf(buf + ret, "Date: %s\n",
-                              show_rfc2822_date(time, tz));
-               break;
-       case CMIT_FMT_FULLER:
-               ret += sprintf(buf + ret, "%sDate: %s\n", what, show_date(time, tz));
-               break;
-       default:
-               /* notin' */
-               break;
+               commit = commit->parents->item;
        }
-       return ret;
 }
 
-static int is_empty_line(const char *line, int *len_p)
-{
-       int len = *len_p;
-       while (len && isspace(line[len-1]))
-               len--;
-       *len_p = len;
-       return !len;
-}
-
-static int add_merge_info(enum cmit_fmt fmt, char *buf, const struct commit *commit, int abbrev)
+void clear_commit_marks(struct commit *commit, unsigned int mark)
 {
-       struct commit_list *parent = commit->parents;
-       int offset;
-
-       if ((fmt == CMIT_FMT_ONELINE) || (fmt == CMIT_FMT_EMAIL) ||
-           !parent || !parent->next)
-               return 0;
-
-       offset = sprintf(buf, "Merge:");
-
-       while (parent) {
-               struct commit *p = parent->item;
-               const char *hex = abbrev
-                       ? find_unique_abbrev(p->object.sha1, abbrev)
-                       : sha1_to_hex(p->object.sha1);
-               const char *dots = (abbrev && strlen(hex) != 40) ? "..." : "";
-               parent = parent->next;
-
-               offset += sprintf(buf + offset, " %s%s", hex, dots);
-       }
-       buf[offset++] = '\n';
-       return offset;
+       struct commit_list *list = NULL;
+       commit_list_insert(commit, &list);
+       while (list)
+               clear_commit_marks_1(&list, pop_commit(&list), mark);
 }
 
-unsigned long pretty_print_commit(enum cmit_fmt fmt, const struct commit *commit, unsigned long len, char *buf, unsigned long space, int abbrev, const char *subject, const char *after_subject)
+void clear_commit_marks_for_object_array(struct object_array *a, unsigned mark)
 {
-       int hdr = 1, body = 0;
-       unsigned long offset = 0;
-       int indent = 4;
-       int parents_shown = 0;
-       const char *msg = commit->buffer;
-       int plain_non_ascii = 0;
-
-       if (fmt == CMIT_FMT_ONELINE || fmt == CMIT_FMT_EMAIL)
-               indent = 0;
-
-       /* After-subject is used to pass in Content-Type: multipart
-        * MIME header; in that case we do not have to do the
-        * plaintext content type even if the commit message has
-        * non 7-bit ASCII character.  Otherwise, check if we need
-        * to say this is not a 7-bit ASCII.
-        */
-       if (fmt == CMIT_FMT_EMAIL && !after_subject) {
-               int i, ch, in_body;
-
-               for (in_body = i = 0; (ch = msg[i]) && i < len; i++) {
-                       if (!in_body) {
-                               /* author could be non 7-bit ASCII but
-                                * the log may so; skip over the
-                                * header part first.
-                                */
-                               if (ch == '\n' &&
-                                   i + 1 < len && msg[i+1] == '\n')
-                                       in_body = 1;
-                       }
-                       else if (ch & 0x80) {
-                               plain_non_ascii = 1;
-                               break;
-                       }
-               }
-       }
-
-       for (;;) {
-               const char *line = msg;
-               int linelen = get_one_line(msg, len);
-
-               if (!linelen)
-                       break;
-
-               /*
-                * We want some slop for indentation and a possible
-                * final "...". Thus the "+ 20".
-                */
-               if (offset + linelen + 20 > space) {
-                       memcpy(buf + offset, "    ...\n", 8);
-                       offset += 8;
-                       break;
-               }
-
-               msg += linelen;
-               len -= linelen;
-               if (hdr) {
-                       if (linelen == 1) {
-                               hdr = 0;
-                               if ((fmt != CMIT_FMT_ONELINE) && !subject)
-                                       buf[offset++] = '\n';
-                               continue;
-                       }
-                       if (fmt == CMIT_FMT_RAW) {
-                               memcpy(buf + offset, line, linelen);
-                               offset += linelen;
-                               continue;
-                       }
-                       if (!memcmp(line, "parent ", 7)) {
-                               if (linelen != 48)
-                                       die("bad parent line in commit");
-                               continue;
-                       }
-
-                       if (!parents_shown) {
-                               offset += add_merge_info(fmt, buf + offset,
-                                                        commit, abbrev);
-                               parents_shown = 1;
-                               continue;
-                       }
-                       /*
-                        * MEDIUM == DEFAULT shows only author with dates.
-                        * FULL shows both authors but not dates.
-                        * FULLER shows both authors and dates.
-                        */
-                       if (!memcmp(line, "author ", 7))
-                               offset += add_user_info("Author", fmt,
-                                                       buf + offset,
-                                                       line + 7);
-                       if (!memcmp(line, "committer ", 10) &&
-                           (fmt == CMIT_FMT_FULL || fmt == CMIT_FMT_FULLER))
-                               offset += add_user_info("Commit", fmt,
-                                                       buf + offset,
-                                                       line + 10);
-                       continue;
-               }
-
-               if (is_empty_line(line, &linelen)) {
-                       if (!body)
-                               continue;
-                       if (subject)
-                               continue;
-                       if (fmt == CMIT_FMT_SHORT)
-                               break;
-               } else {
-                       body = 1;
-               }
-
-               if (subject) {
-                       int slen = strlen(subject);
-                       memcpy(buf + offset, subject, slen);
-                       offset += slen;
-                       offset += add_rfc2047(buf + offset, line, linelen);
-               }
-               else {
-                       memset(buf + offset, ' ', indent);
-                       memcpy(buf + offset + indent, line, linelen);
-                       offset += linelen + indent;
-               }
-               buf[offset++] = '\n';
-               if (fmt == CMIT_FMT_ONELINE)
-                       break;
-               if (subject && plain_non_ascii) {
-                       static const char header[] =
-                               "Content-Type: text/plain; charset=UTF-8\n"
-                               "Content-Transfer-Encoding: 8bit\n";
-                       memcpy(buf + offset, header, sizeof(header)-1);
-                       offset += sizeof(header)-1;
-               }
-               if (after_subject) {
-                       int slen = strlen(after_subject);
-                       if (slen > space - offset - 1)
-                               slen = space - offset - 1;
-                       memcpy(buf + offset, after_subject, slen);
-                       offset += slen;
-                       after_subject = NULL;
-               }
-               subject = NULL;
+       struct object *object;
+       struct commit *commit;
+       unsigned int i;
+
+       for (i = 0; i < a->nr; i++) {
+               object = a->objects[i].item;
+               commit = lookup_commit_reference_gently(object->sha1, 1);
+               if (commit)
+                       clear_commit_marks(commit, mark);
        }
-       while (offset && isspace(buf[offset-1]))
-               offset--;
-       /* Make sure there is an EOLN for the non-oneline case */
-       if (fmt != CMIT_FMT_ONELINE)
-               buf[offset++] = '\n';
-       buf[offset] = '\0';
-       return offset;
 }
 
 struct commit *pop_commit(struct commit_list **stack)
@@ -718,143 +497,105 @@ struct commit *pop_commit(struct commit_list **stack)
        return item;
 }
 
-int count_parents(struct commit * commit)
-{
-        int count = 0;
-        struct commit_list * parents = commit->parents;
-        for (count=0;parents; parents=parents->next,count++)
-          ;
-        return count;
-}
-
-void topo_sort_default_setter(struct commit *c, void *data)
-{
-       c->util = data;
-}
-
-void *topo_sort_default_getter(struct commit *c)
-{
-       return c->util;
-}
-
 /*
  * Performs an in-place topological sort on the list supplied.
  */
 void sort_in_topological_order(struct commit_list ** list, int lifo)
 {
-       sort_in_topological_order_fn(list, lifo, topo_sort_default_setter,
-                                    topo_sort_default_getter);
-}
-
-void sort_in_topological_order_fn(struct commit_list ** list, int lifo,
-                                 topo_sort_set_fn_t setter,
-                                 topo_sort_get_fn_t getter)
-{
-       struct commit_list * next = *list;
-       struct commit_list * work = NULL, **insert;
-       struct commit_list ** pptr = list;
-       struct sort_node * nodes;
-       struct sort_node * next_nodes;
-       int count = 0;
+       struct commit_list *next, *orig = *list;
+       struct commit_list *work, **insert;
+       struct commit_list **pptr;
 
-       /* determine the size of the list */
-       while (next) {
-               next = next->next;
-               count++;
-       }
-       
-       if (!count)
+       if (!orig)
                return;
-       /* allocate an array to help sort the list */
-       nodes = xcalloc(count, sizeof(*nodes));
-       /* link the list to the array */
-       next_nodes = nodes;
-       next=*list;
-       while (next) {
-               next_nodes->list_item = next;
-               setter(next->item, next_nodes);
-               next_nodes++;
-               next = next->next;
+       *list = NULL;
+
+       /* Mark them and clear the indegree */
+       for (next = orig; next; next = next->next) {
+               struct commit *commit = next->item;
+               commit->indegree = 1;
        }
+
        /* update the indegree */
-       next=*list;
-       while (next) {
+       for (next = orig; next; next = next->next) {
                struct commit_list * parents = next->item->parents;
                while (parents) {
-                       struct commit * parent=parents->item;
-                       struct sort_node * pn = (struct sort_node *) getter(parent);
+                       struct commit *parent = parents->item;
 
-                       if (pn)
-                               pn->indegree++;
-                       parents=parents->next;
+                       if (parent->indegree)
+                               parent->indegree++;
+                       parents = parents->next;
                }
-               next=next->next;
-       }
-       /* 
-         * find the tips
-         *
-         * tips are nodes not reachable from any other node in the list 
-         * 
-         * the tips serve as a starting set for the work queue.
-         */
-       next=*list;
+       }
+
+       /*
+        * find the tips
+        *
+        * tips are nodes not reachable from any other node in the list
+        *
+        * the tips serve as a starting set for the work queue.
+        */
+       work = NULL;
        insert = &work;
-       while (next) {
-               struct sort_node * node = (struct sort_node *) getter(next->item);
+       for (next = orig; next; next = next->next) {
+               struct commit *commit = next->item;
 
-               if (node->indegree == 0) {
-                       insert = &commit_list_insert(next->item, insert)->next;
-               }
-               next=next->next;
+               if (commit->indegree == 1)
+                       insert = &commit_list_insert(commit, insert)->next;
        }
 
        /* process the list in topological order */
        if (!lifo)
-               sort_by_date(&work);
+               commit_list_sort_by_date(&work);
+
+       pptr = list;
+       *list = NULL;
        while (work) {
-               struct commit * work_item = pop_commit(&work);
-               struct sort_node * work_node = (struct sort_node *) getter(work_item);
-               struct commit_list * parents = work_item->parents;
+               struct commit *commit;
+               struct commit_list *parents, *work_item;
 
-               while (parents) {
-                       struct commit * parent=parents->item;
-                       struct sort_node * pn = (struct sort_node *) getter(parent);
-
-                       if (pn) {
-                               /*
-                                * parents are only enqueued for emission 
-                                 * when all their children have been emitted thereby
-                                 * guaranteeing topological order.
-                                 */
-                               pn->indegree--;
-                               if (!pn->indegree) {
-                                       if (!lifo)
-                                               insert_by_date(parent, &work);
-                                       else
-                                               commit_list_insert(parent, &work);
-                               }
+               work_item = work;
+               work = work_item->next;
+               work_item->next = NULL;
+
+               commit = work_item->item;
+               for (parents = commit->parents; parents ; parents = parents->next) {
+                       struct commit *parent = parents->item;
+
+                       if (!parent->indegree)
+                               continue;
+
+                       /*
+                        * parents are only enqueued for emission
+                        * when all their children have been emitted thereby
+                        * guaranteeing topological order.
+                        */
+                       if (--parent->indegree == 1) {
+                               if (!lifo)
+                                       commit_list_insert_by_date(parent, &work);
+                               else
+                                       commit_list_insert(parent, &work);
                        }
-                       parents=parents->next;
                }
                /*
-                 * work_item is a commit all of whose children
-                 * have already been emitted. we can emit it now.
-                 */
-               *pptr = work_node->list_item;
-               pptr = &(*pptr)->next;
-               *pptr = NULL;
-               setter(work_item, NULL);
+                * work_item is a commit all of whose children
+                * have already been emitted. we can emit it now.
+                */
+               commit->indegree = 0;
+               *pptr = work_item;
+               pptr = &work_item->next;
        }
-       free(nodes);
 }
 
-/* merge-rebase stuff */
+/* merge-base stuff */
 
-/* bits #0..7 in revision.h */
-#define PARENT1                (1u<< 8)
-#define PARENT2                (1u<< 9)
-#define STALE          (1u<<10)
-#define RESULT         (1u<<11)
+/* bits #0..15 in revision.h */
+#define PARENT1                (1u<<16)
+#define PARENT2                (1u<<17)
+#define STALE          (1u<<18)
+#define RESULT         (1u<<19)
+
+static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
 
 static struct commit *interesting(struct commit_list *list)
 {
@@ -868,41 +609,38 @@ static struct commit *interesting(struct commit_list *list)
        return NULL;
 }
 
-static struct commit_list *merge_bases(struct commit *one, struct commit *two)
+/* all input commits in one and twos[] must have been parsed! */
+static struct commit_list *paint_down_to_common(struct commit *one, int n, struct commit **twos)
 {
        struct commit_list *list = NULL;
        struct commit_list *result = NULL;
-
-       if (one == two)
-               /* We do not mark this even with RESULT so we do not
-                * have to clean it up.
-                */
-               return commit_list_insert(one, &result);
-
-       parse_commit(one);
-       parse_commit(two);
+       int i;
 
        one->object.flags |= PARENT1;
-       two->object.flags |= PARENT2;
-       insert_by_date(one, &list);
-       insert_by_date(two, &list);
+       commit_list_insert_by_date(one, &list);
+       if (!n)
+               return list;
+       for (i = 0; i < n; i++) {
+               twos[i]->object.flags |= PARENT2;
+               commit_list_insert_by_date(twos[i], &list);
+       }
 
        while (interesting(list)) {
                struct commit *commit;
                struct commit_list *parents;
-               struct commit_list *n;
+               struct commit_list *next;
                int flags;
 
                commit = list->item;
-               n = list->next;
+               next = list->next;
                free(list);
-               list = n;
+               list = next;
 
                flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
                if (flags == (PARENT1 | PARENT2)) {
                        if (!(commit->object.flags & RESULT)) {
                                commit->object.flags |= RESULT;
-                               insert_by_date(commit, &result);
+                               commit_list_insert_by_date(commit, &result);
                        }
                        /* Mark parents of a found merge stale */
                        flags |= STALE;
@@ -913,41 +651,154 @@ static struct commit_list *merge_bases(struct commit *one, struct commit *two)
                        parents = parents->next;
                        if ((p->object.flags & flags) == flags)
                                continue;
-                       parse_commit(p);
+                       if (parse_commit(p))
+                               return NULL;
                        p->object.flags |= flags;
-                       insert_by_date(p, &list);
+                       commit_list_insert_by_date(p, &list);
                }
        }
 
-       /* Clean up the result to remove stale ones */
-       list = result; result = NULL;
+       free_commit_list(list);
+       return result;
+}
+
+static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
+{
+       struct commit_list *list = NULL;
+       struct commit_list *result = NULL;
+       int i;
+
+       for (i = 0; i < n; i++) {
+               if (one == twos[i])
+                       /*
+                        * We do not mark this even with RESULT so we do not
+                        * have to clean it up.
+                        */
+                       return commit_list_insert(one, &result);
+       }
+
+       if (parse_commit(one))
+               return NULL;
+       for (i = 0; i < n; i++) {
+               if (parse_commit(twos[i]))
+                       return NULL;
+       }
+
+       list = paint_down_to_common(one, n, twos);
+
        while (list) {
-               struct commit_list *n = list->next;
+               struct commit_list *next = list->next;
                if (!(list->item->object.flags & STALE))
-                       insert_by_date(list->item, &result);
+                       commit_list_insert_by_date(list->item, &result);
                free(list);
-               list = n;
+               list = next;
        }
        return result;
 }
 
-struct commit_list *get_merge_bases(struct commit *one,
-                                   struct commit *two,
-                                    int cleanup)
+struct commit_list *get_octopus_merge_bases(struct commit_list *in)
+{
+       struct commit_list *i, *j, *k, *ret = NULL;
+       struct commit_list **pptr = &ret;
+
+       for (i = in; i; i = i->next) {
+               if (!ret)
+                       pptr = &commit_list_insert(i->item, pptr)->next;
+               else {
+                       struct commit_list *new = NULL, *end = NULL;
+
+                       for (j = ret; j; j = j->next) {
+                               struct commit_list *bases;
+                               bases = get_merge_bases(i->item, j->item, 1);
+                               if (!new)
+                                       new = bases;
+                               else
+                                       end->next = bases;
+                               for (k = bases; k; k = k->next)
+                                       end = k;
+                       }
+                       ret = new;
+               }
+       }
+       return ret;
+}
+
+static int remove_redundant(struct commit **array, int cnt)
+{
+       /*
+        * Some commit in the array may be an ancestor of
+        * another commit.  Move such commit to the end of
+        * the array, and return the number of commits that
+        * are independent from each other.
+        */
+       struct commit **work;
+       unsigned char *redundant;
+       int *filled_index;
+       int i, j, filled;
+
+       work = xcalloc(cnt, sizeof(*work));
+       redundant = xcalloc(cnt, 1);
+       filled_index = xmalloc(sizeof(*filled_index) * (cnt - 1));
+
+       for (i = 0; i < cnt; i++)
+               parse_commit(array[i]);
+       for (i = 0; i < cnt; i++) {
+               struct commit_list *common;
+
+               if (redundant[i])
+                       continue;
+               for (j = filled = 0; j < cnt; j++) {
+                       if (i == j || redundant[j])
+                               continue;
+                       filled_index[filled] = j;
+                       work[filled++] = array[j];
+               }
+               common = paint_down_to_common(array[i], filled, work);
+               if (array[i]->object.flags & PARENT2)
+                       redundant[i] = 1;
+               for (j = 0; j < filled; j++)
+                       if (work[j]->object.flags & PARENT1)
+                               redundant[filled_index[j]] = 1;
+               clear_commit_marks(array[i], all_flags);
+               for (j = 0; j < filled; j++)
+                       clear_commit_marks(work[j], all_flags);
+               free_commit_list(common);
+       }
+
+       /* Now collect the result */
+       memcpy(work, array, sizeof(*array) * cnt);
+       for (i = filled = 0; i < cnt; i++)
+               if (!redundant[i])
+                       array[filled++] = work[i];
+       for (j = filled, i = 0; i < cnt; i++)
+               if (redundant[i])
+                       array[j++] = work[i];
+       free(work);
+       free(redundant);
+       free(filled_index);
+       return filled;
+}
+
+struct commit_list *get_merge_bases_many(struct commit *one,
+                                        int n,
+                                        struct commit **twos,
+                                        int cleanup)
 {
-       const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
        struct commit_list *list;
        struct commit **rslt;
        struct commit_list *result;
-       int cnt, i, j;
+       int cnt, i;
 
-       result = merge_bases(one, two);
-       if (one == two)
-               return result;
+       result = merge_bases_many(one, n, twos);
+       for (i = 0; i < n; i++) {
+               if (one == twos[i])
+                       return result;
+       }
        if (!result || !result->next) {
                if (cleanup) {
                        clear_commit_marks(one, all_flags);
-                       clear_commit_marks(two, all_flags);
+                       for (i = 0; i < n; i++)
+                               clear_commit_marks(twos[i], all_flags);
                }
                return result;
        }
@@ -965,29 +816,544 @@ struct commit_list *get_merge_bases(struct commit *one,
        free_commit_list(result);
 
        clear_commit_marks(one, all_flags);
-       clear_commit_marks(two, all_flags);
-       for (i = 0; i < cnt - 1; i++) {
-               for (j = i+1; j < cnt; j++) {
-                       if (!rslt[i] || !rslt[j])
-                               continue;
-                       result = merge_bases(rslt[i], rslt[j]);
-                       clear_commit_marks(rslt[i], all_flags);
-                       clear_commit_marks(rslt[j], all_flags);
-                       for (list = result; list; list = list->next) {
-                               if (rslt[i] == list->item)
-                                       rslt[i] = NULL;
-                               if (rslt[j] == list->item)
-                                       rslt[j] = NULL;
-                       }
+       for (i = 0; i < n; i++)
+               clear_commit_marks(twos[i], all_flags);
+
+       cnt = remove_redundant(rslt, cnt);
+       result = NULL;
+       for (i = 0; i < cnt; i++)
+               commit_list_insert_by_date(rslt[i], &result);
+       free(rslt);
+       return result;
+}
+
+struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
+                                   int cleanup)
+{
+       return get_merge_bases_many(one, 1, &two, cleanup);
+}
+
+/*
+ * Is "commit" a decendant of one of the elements on the "with_commit" list?
+ */
+int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
+{
+       if (!with_commit)
+               return 1;
+       while (with_commit) {
+               struct commit *other;
+
+               other = with_commit->item;
+               with_commit = with_commit->next;
+               if (in_merge_bases(other, commit))
+                       return 1;
+       }
+       return 0;
+}
+
+/*
+ * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
+ */
+int in_merge_bases(struct commit *commit, struct commit *reference)
+{
+       struct commit_list *bases;
+       int ret = 0;
+
+       if (parse_commit(commit) || parse_commit(reference))
+               return ret;
+
+       bases = paint_down_to_common(commit, 1, &reference);
+       if (commit->object.flags & PARENT2)
+               ret = 1;
+       clear_commit_marks(commit, all_flags);
+       clear_commit_marks(reference, all_flags);
+       free_commit_list(bases);
+       return ret;
+}
+
+struct commit_list *reduce_heads(struct commit_list *heads)
+{
+       struct commit_list *p;
+       struct commit_list *result = NULL, **tail = &result;
+       struct commit **array;
+       int num_head, i;
+
+       if (!heads)
+               return NULL;
+
+       /* Uniquify */
+       for (p = heads; p; p = p->next)
+               p->item->object.flags &= ~STALE;
+       for (p = heads, num_head = 0; p; p = p->next) {
+               if (p->item->object.flags & STALE)
+                       continue;
+               p->item->object.flags |= STALE;
+               num_head++;
+       }
+       array = xcalloc(sizeof(*array), num_head);
+       for (p = heads, i = 0; p; p = p->next) {
+               if (p->item->object.flags & STALE) {
+                       array[i++] = p->item;
+                       p->item->object.flags &= ~STALE;
                }
        }
+       num_head = remove_redundant(array, num_head);
+       for (i = 0; i < num_head; i++)
+               tail = &commit_list_insert(array[i], tail)->next;
+       return result;
+}
 
-       /* Surviving ones in rslt[] are the independent results */
-       result = NULL;
-       for (i = 0; i < cnt; i++) {
-               if (rslt[i])
-                       insert_by_date(rslt[i], &result);
+static const char gpg_sig_header[] = "gpgsig";
+static const int gpg_sig_header_len = sizeof(gpg_sig_header) - 1;
+
+static int do_sign_commit(struct strbuf *buf, const char *keyid)
+{
+       struct strbuf sig = STRBUF_INIT;
+       int inspos, copypos;
+
+       /* find the end of the header */
+       inspos = strstr(buf->buf, "\n\n") - buf->buf + 1;
+
+       if (!keyid || !*keyid)
+               keyid = get_signing_key();
+       if (sign_buffer(buf, &sig, keyid)) {
+               strbuf_release(&sig);
+               return -1;
        }
-       free(rslt);
+
+       for (copypos = 0; sig.buf[copypos]; ) {
+               const char *bol = sig.buf + copypos;
+               const char *eol = strchrnul(bol, '\n');
+               int len = (eol - bol) + !!*eol;
+
+               if (!copypos) {
+                       strbuf_insert(buf, inspos, gpg_sig_header, gpg_sig_header_len);
+                       inspos += gpg_sig_header_len;
+               }
+               strbuf_insert(buf, inspos++, " ", 1);
+               strbuf_insert(buf, inspos, bol, len);
+               inspos += len;
+               copypos += len;
+       }
+       strbuf_release(&sig);
+       return 0;
+}
+
+int parse_signed_commit(const unsigned char *sha1,
+                       struct strbuf *payload, struct strbuf *signature)
+{
+       unsigned long size;
+       enum object_type type;
+       char *buffer = read_sha1_file(sha1, &type, &size);
+       int in_signature, saw_signature = -1;
+       char *line, *tail;
+
+       if (!buffer || type != OBJ_COMMIT)
+               goto cleanup;
+
+       line = buffer;
+       tail = buffer + size;
+       in_signature = 0;
+       saw_signature = 0;
+       while (line < tail) {
+               const char *sig = NULL;
+               char *next = memchr(line, '\n', tail - line);
+
+               next = next ? next + 1 : tail;
+               if (in_signature && line[0] == ' ')
+                       sig = line + 1;
+               else if (!prefixcmp(line, gpg_sig_header) &&
+                        line[gpg_sig_header_len] == ' ')
+                       sig = line + gpg_sig_header_len + 1;
+               if (sig) {
+                       strbuf_add(signature, sig, next - sig);
+                       saw_signature = 1;
+                       in_signature = 1;
+               } else {
+                       if (*line == '\n')
+                               /* dump the whole remainder of the buffer */
+                               next = tail;
+                       strbuf_add(payload, line, next - line);
+                       in_signature = 0;
+               }
+               line = next;
+       }
+ cleanup:
+       free(buffer);
+       return saw_signature;
+}
+
+static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
+{
+       struct merge_remote_desc *desc;
+       struct commit_extra_header *mergetag;
+       char *buf;
+       unsigned long size, len;
+       enum object_type type;
+
+       desc = merge_remote_util(parent);
+       if (!desc || !desc->obj)
+               return;
+       buf = read_sha1_file(desc->obj->sha1, &type, &size);
+       if (!buf || type != OBJ_TAG)
+               goto free_return;
+       len = parse_signature(buf, size);
+       if (size == len)
+               goto free_return;
+       /*
+        * We could verify this signature and either omit the tag when
+        * it does not validate, but the integrator may not have the
+        * public key of the signer of the tag he is merging, while a
+        * later auditor may have it while auditing, so let's not run
+        * verify-signed-buffer here for now...
+        *
+        * if (verify_signed_buffer(buf, len, buf + len, size - len, ...))
+        *      warn("warning: signed tag unverified.");
+        */
+       mergetag = xcalloc(1, sizeof(*mergetag));
+       mergetag->key = xstrdup("mergetag");
+       mergetag->value = buf;
+       mergetag->len = size;
+
+       **tail = mergetag;
+       *tail = &mergetag->next;
+       return;
+
+free_return:
+       free(buf);
+}
+
+void append_merge_tag_headers(struct commit_list *parents,
+                             struct commit_extra_header ***tail)
+{
+       while (parents) {
+               struct commit *parent = parents->item;
+               handle_signed_tag(parent, tail);
+               parents = parents->next;
+       }
+}
+
+static void add_extra_header(struct strbuf *buffer,
+                            struct commit_extra_header *extra)
+{
+       strbuf_addstr(buffer, extra->key);
+       if (extra->len)
+               strbuf_add_lines(buffer, " ", extra->value, extra->len);
+       else
+               strbuf_addch(buffer, '\n');
+}
+
+struct commit_extra_header *read_commit_extra_headers(struct commit *commit,
+                                                     const char **exclude)
+{
+       struct commit_extra_header *extra = NULL;
+       unsigned long size;
+       enum object_type type;
+       char *buffer = read_sha1_file(commit->object.sha1, &type, &size);
+       if (buffer && type == OBJ_COMMIT)
+               extra = read_commit_extra_header_lines(buffer, size, exclude);
+       free(buffer);
+       return extra;
+}
+
+static inline int standard_header_field(const char *field, size_t len)
+{
+       return ((len == 4 && !memcmp(field, "tree ", 5)) ||
+               (len == 6 && !memcmp(field, "parent ", 7)) ||
+               (len == 6 && !memcmp(field, "author ", 7)) ||
+               (len == 9 && !memcmp(field, "committer ", 10)) ||
+               (len == 8 && !memcmp(field, "encoding ", 9)));
+}
+
+static int excluded_header_field(const char *field, size_t len, const char **exclude)
+{
+       if (!exclude)
+               return 0;
+
+       while (*exclude) {
+               size_t xlen = strlen(*exclude);
+               if (len == xlen &&
+                   !memcmp(field, *exclude, xlen) && field[xlen] == ' ')
+                       return 1;
+               exclude++;
+       }
+       return 0;
+}
+
+static struct commit_extra_header *read_commit_extra_header_lines(
+       const char *buffer, size_t size,
+       const char **exclude)
+{
+       struct commit_extra_header *extra = NULL, **tail = &extra, *it = NULL;
+       const char *line, *next, *eof, *eob;
+       struct strbuf buf = STRBUF_INIT;
+
+       for (line = buffer, eob = line + size;
+            line < eob && *line != '\n';
+            line = next) {
+               next = memchr(line, '\n', eob - line);
+               next = next ? next + 1 : eob;
+               if (*line == ' ') {
+                       /* continuation */
+                       if (it)
+                               strbuf_add(&buf, line + 1, next - (line + 1));
+                       continue;
+               }
+               if (it)
+                       it->value = strbuf_detach(&buf, &it->len);
+               strbuf_reset(&buf);
+               it = NULL;
+
+               eof = strchr(line, ' ');
+               if (next <= eof)
+                       eof = next;
+
+               if (standard_header_field(line, eof - line) ||
+                   excluded_header_field(line, eof - line, exclude))
+                       continue;
+
+               it = xcalloc(1, sizeof(*it));
+               it->key = xmemdupz(line, eof-line);
+               *tail = it;
+               tail = &it->next;
+               if (eof + 1 < next)
+                       strbuf_add(&buf, eof + 1, next - (eof + 1));
+       }
+       if (it)
+               it->value = strbuf_detach(&buf, &it->len);
+       return extra;
+}
+
+void free_commit_extra_headers(struct commit_extra_header *extra)
+{
+       while (extra) {
+               struct commit_extra_header *next = extra->next;
+               free(extra->key);
+               free(extra->value);
+               free(extra);
+               extra = next;
+       }
+}
+
+int commit_tree(const struct strbuf *msg, unsigned char *tree,
+               struct commit_list *parents, unsigned char *ret,
+               const char *author, const char *sign_commit)
+{
+       struct commit_extra_header *extra = NULL, **tail = &extra;
+       int result;
+
+       append_merge_tag_headers(parents, &tail);
+       result = commit_tree_extended(msg, tree, parents, ret,
+                                     author, sign_commit, extra);
+       free_commit_extra_headers(extra);
+       return result;
+}
+
+static int find_invalid_utf8(const char *buf, int len)
+{
+       int offset = 0;
+
+       while (len) {
+               unsigned char c = *buf++;
+               int bytes, bad_offset;
+
+               len--;
+               offset++;
+
+               /* Simple US-ASCII? No worries. */
+               if (c < 0x80)
+                       continue;
+
+               bad_offset = offset-1;
+
+               /*
+                * Count how many more high bits set: that's how
+                * many more bytes this sequence should have.
+                */
+               bytes = 0;
+               while (c & 0x40) {
+                       c <<= 1;
+                       bytes++;
+               }
+
+               /* Must be between 1 and 5 more bytes */
+               if (bytes < 1 || bytes > 5)
+                       return bad_offset;
+
+               /* Do we *have* that many bytes? */
+               if (len < bytes)
+                       return bad_offset;
+
+               offset += bytes;
+               len -= bytes;
+
+               /* And verify that they are good continuation bytes */
+               do {
+                       if ((*buf++ & 0xc0) != 0x80)
+                               return bad_offset;
+               } while (--bytes);
+
+               /* We could/should check the value and length here too */
+       }
+       return -1;
+}
+
+/*
+ * This verifies that the buffer is in proper utf8 format.
+ *
+ * If it isn't, it assumes any non-utf8 characters are Latin1,
+ * and does the conversion.
+ *
+ * Fixme: we should probably also disallow overlong forms and
+ * invalid characters. But we don't do that currently.
+ */
+static int verify_utf8(struct strbuf *buf)
+{
+       int ok = 1;
+       long pos = 0;
+
+       for (;;) {
+               int bad;
+               unsigned char c;
+               unsigned char replace[2];
+
+               bad = find_invalid_utf8(buf->buf + pos, buf->len - pos);
+               if (bad < 0)
+                       return ok;
+               pos += bad;
+               ok = 0;
+               c = buf->buf[pos];
+               strbuf_remove(buf, pos, 1);
+
+               /* We know 'c' must be in the range 128-255 */
+               replace[0] = 0xc0 + (c >> 6);
+               replace[1] = 0x80 + (c & 0x3f);
+               strbuf_insert(buf, pos, replace, 2);
+               pos += 2;
+       }
+}
+
+static const char commit_utf8_warn[] =
+"Warning: commit message did not conform to UTF-8.\n"
+"You may want to amend it after fixing the message, or set the config\n"
+"variable i18n.commitencoding to the encoding your project uses.\n";
+
+int commit_tree_extended(const struct strbuf *msg, unsigned char *tree,
+                        struct commit_list *parents, unsigned char *ret,
+                        const char *author, const char *sign_commit,
+                        struct commit_extra_header *extra)
+{
+       int result;
+       int encoding_is_utf8;
+       struct strbuf buffer;
+
+       assert_sha1_type(tree, OBJ_TREE);
+
+       if (memchr(msg->buf, '\0', msg->len))
+               return error("a NUL byte in commit log message not allowed.");
+
+       /* Not having i18n.commitencoding is the same as having utf-8 */
+       encoding_is_utf8 = is_encoding_utf8(git_commit_encoding);
+
+       strbuf_init(&buffer, 8192); /* should avoid reallocs for the headers */
+       strbuf_addf(&buffer, "tree %s\n", sha1_to_hex(tree));
+
+       /*
+        * NOTE! This ordering means that the same exact tree merged with a
+        * different order of parents will be a _different_ changeset even
+        * if everything else stays the same.
+        */
+       while (parents) {
+               struct commit_list *next = parents->next;
+               struct commit *parent = parents->item;
+
+               strbuf_addf(&buffer, "parent %s\n",
+                           sha1_to_hex(parent->object.sha1));
+               free(parents);
+               parents = next;
+       }
+
+       /* Person/date information */
+       if (!author)
+               author = git_author_info(IDENT_STRICT);
+       strbuf_addf(&buffer, "author %s\n", author);
+       strbuf_addf(&buffer, "committer %s\n", git_committer_info(IDENT_STRICT));
+       if (!encoding_is_utf8)
+               strbuf_addf(&buffer, "encoding %s\n", git_commit_encoding);
+
+       while (extra) {
+               add_extra_header(&buffer, extra);
+               extra = extra->next;
+       }
+       strbuf_addch(&buffer, '\n');
+
+       /* And add the comment */
+       strbuf_addbuf(&buffer, msg);
+
+       /* And check the encoding */
+       if (encoding_is_utf8 && !verify_utf8(&buffer))
+               fprintf(stderr, commit_utf8_warn);
+
+       if (sign_commit && do_sign_commit(&buffer, sign_commit))
+               return -1;
+
+       result = write_sha1_file(buffer.buf, buffer.len, commit_type, ret);
+       strbuf_release(&buffer);
        return result;
 }
+
+struct commit *get_merge_parent(const char *name)
+{
+       struct object *obj;
+       struct commit *commit;
+       unsigned char sha1[20];
+       if (get_sha1(name, sha1))
+               return NULL;
+       obj = parse_object(sha1);
+       commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
+       if (commit && !commit->util) {
+               struct merge_remote_desc *desc;
+               desc = xmalloc(sizeof(*desc));
+               desc->obj = obj;
+               desc->name = strdup(name);
+               commit->util = desc;
+       }
+       return commit;
+}
+
+/*
+ * 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;
+ */
+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;
+}
+
+void print_commit_list(struct commit_list *list,
+                      const char *format_cur,
+                      const char *format_last)
+{
+       for ( ; list; list = list->next) {
+               const char *format = list->next ? format_cur : format_last;
+               printf(format, sha1_to_hex(list->item->object.sha1));
+       }
+}