match_explicit: hoist refspec lhs checks into their own function
[gitweb.git] / remote.c
index efcba931eca963bd6a5fd13f01a4859e0ae9e14d..6aa9dd24617e6123ffed32bffc2f02d3be379a2b 100644 (file)
--- a/remote.c
+++ b/remote.c
@@ -76,7 +76,7 @@ static const char *alias_url(const char *url, struct rewrites *r)
                if (!r->rewrite[i])
                        continue;
                for (j = 0; j < r->rewrite[i]->instead_of_nr; j++) {
-                       if (!prefixcmp(url, r->rewrite[i]->instead_of[j].s) &&
+                       if (starts_with(url, r->rewrite[i]->instead_of[j].s) &&
                            (!longest ||
                             longest->len < r->rewrite[i]->instead_of[j].len)) {
                                longest = &(r->rewrite[i]->instead_of[j]);
@@ -148,6 +148,7 @@ static struct remote *make_remote(const char *name, int len)
        }
 
        ret = xcalloc(1, sizeof(struct remote));
+       ret->prune = -1;  /* unspecified */
        ALLOC_GROW(remotes, remotes_nr + 1, remotes_alloc);
        remotes[remotes_nr++] = ret;
        if (len)
@@ -238,13 +239,13 @@ static void read_remotes_file(struct remote *remote)
                int value_list;
                char *s, *p;
 
-               if (!prefixcmp(buffer, "URL:")) {
+               if (starts_with(buffer, "URL:")) {
                        value_list = 0;
                        s = buffer + 4;
-               } else if (!prefixcmp(buffer, "Push:")) {
+               } else if (starts_with(buffer, "Push:")) {
                        value_list = 1;
                        s = buffer + 5;
-               } else if (!prefixcmp(buffer, "Pull:")) {
+               } else if (starts_with(buffer, "Pull:")) {
                        value_list = 2;
                        s = buffer + 5;
                } else
@@ -336,7 +337,7 @@ static int handle_config(const char *key, const char *value, void *cb)
        const char *subkey;
        struct remote *remote;
        struct branch *branch;
-       if (!prefixcmp(key, "branch.")) {
+       if (starts_with(key, "branch.")) {
                name = key + 7;
                subkey = strrchr(name, '.');
                if (!subkey)
@@ -360,7 +361,7 @@ static int handle_config(const char *key, const char *value, void *cb)
                }
                return 0;
        }
-       if (!prefixcmp(key, "url.")) {
+       if (starts_with(key, "url.")) {
                struct rewrite *rewrite;
                name = key + 4;
                subkey = strrchr(name, '.');
@@ -379,7 +380,7 @@ static int handle_config(const char *key, const char *value, void *cb)
                }
        }
 
-       if (prefixcmp(key,  "remote."))
+       if (!starts_with(key,  "remote."))
                return 0;
        name = key + 7;
 
@@ -404,6 +405,8 @@ static int handle_config(const char *key, const char *value, void *cb)
                remote->skip_default_update = git_config_bool(key, value);
        else if (!strcmp(subkey, ".skipfetchall"))
                remote->skip_default_update = git_config_bool(key, value);
+       else if (!strcmp(subkey, ".prune"))
+               remote->prune = git_config_bool(key, value);
        else if (!strcmp(subkey, ".url")) {
                const char *v;
                if (git_config_string(&v, key, value))
@@ -480,11 +483,11 @@ static void read_config(void)
        int flag;
        if (default_remote_name) /* did this already */
                return;
-       default_remote_name = xstrdup("origin");
+       default_remote_name = "origin";
        current_branch = NULL;
        head_ref = resolve_ref_unsafe("HEAD", sha1, 0, &flag);
        if (head_ref && (flag & REF_ISSYMREF) &&
-           !prefixcmp(head_ref, "refs/heads/")) {
+           starts_with(head_ref, "refs/heads/")) {
                current_branch =
                        make_branch(head_ref + strlen("refs/heads/"), 0);
        }
@@ -742,35 +745,66 @@ int for_each_remote(each_remote_fn fn, void *priv)
        return result;
 }
 
-void ref_remove_duplicates(struct ref *ref_map)
+static void handle_duplicate(struct ref *ref1, struct ref *ref2)
+{
+       if (strcmp(ref1->name, ref2->name)) {
+               if (ref1->fetch_head_status != FETCH_HEAD_IGNORE &&
+                   ref2->fetch_head_status != FETCH_HEAD_IGNORE) {
+                       die(_("Cannot fetch both %s and %s to %s"),
+                           ref1->name, ref2->name, ref2->peer_ref->name);
+               } else if (ref1->fetch_head_status != FETCH_HEAD_IGNORE &&
+                          ref2->fetch_head_status == FETCH_HEAD_IGNORE) {
+                       warning(_("%s usually tracks %s, not %s"),
+                               ref2->peer_ref->name, ref2->name, ref1->name);
+               } else if (ref1->fetch_head_status == FETCH_HEAD_IGNORE &&
+                          ref2->fetch_head_status == FETCH_HEAD_IGNORE) {
+                       die(_("%s tracks both %s and %s"),
+                           ref2->peer_ref->name, ref1->name, ref2->name);
+               } else {
+                       /*
+                        * This last possibility doesn't occur because
+                        * FETCH_HEAD_IGNORE entries always appear at
+                        * the end of the list.
+                        */
+                       die(_("Internal error"));
+               }
+       }
+       free(ref2->peer_ref);
+       free(ref2);
+}
+
+struct ref *ref_remove_duplicates(struct ref *ref_map)
 {
        struct string_list refs = STRING_LIST_INIT_NODUP;
-       struct string_list_item *item = NULL;
-       struct ref *prev = NULL, *next = NULL;
-       for (; ref_map; prev = ref_map, ref_map = next) {
-               next = ref_map->next;
-               if (!ref_map->peer_ref)
-                       continue;
+       struct ref *retval = NULL;
+       struct ref **p = &retval;
 
-               item = string_list_lookup(&refs, ref_map->peer_ref->name);
-               if (item) {
-                       if (strcmp(((struct ref *)item->util)->name,
-                                  ref_map->name))
-                               die("%s tracks both %s and %s",
-                                   ref_map->peer_ref->name,
-                                   ((struct ref *)item->util)->name,
-                                   ref_map->name);
-                       prev->next = ref_map->next;
-                       free(ref_map->peer_ref);
-                       free(ref_map);
-                       ref_map = prev; /* skip this; we freed it */
-                       continue;
-               }
+       while (ref_map) {
+               struct ref *ref = ref_map;
+
+               ref_map = ref_map->next;
+               ref->next = NULL;
+
+               if (!ref->peer_ref) {
+                       *p = ref;
+                       p = &ref->next;
+               } else {
+                       struct string_list_item *item =
+                               string_list_insert(&refs, ref->peer_ref->name);
 
-               item = string_list_insert(&refs, ref_map->peer_ref->name);
-               item->util = ref_map;
+                       if (item->util) {
+                               /* Entry already existed */
+                               handle_duplicate((struct ref *)item->util, ref);
+                       } else {
+                               *p = ref;
+                               p = &ref->next;
+                               item->util = ref;
+                       }
+               }
        }
+
        string_list_clear(&refs, 0);
+       return retval;
 }
 
 int remote_has_url(struct remote *remote, const char *url)
@@ -818,10 +852,12 @@ static int match_name_with_pattern(const char *key, const char *name,
        return ret;
 }
 
-static int query_refspecs(struct refspec *refs, int ref_count, struct refspec *query)
+int query_refspecs(struct refspec *refs, int ref_count, struct refspec *query)
 {
        int i;
        int find_src = !query->src;
+       const char *needle = find_src ? query->dst : query->src;
+       char **result = find_src ? &query->src : &query->dst;
 
        if (find_src && !query->dst)
                return error("query_refspecs: need either src or dst");
@@ -830,8 +866,6 @@ static int query_refspecs(struct refspec *refs, int ref_count, struct refspec *q
                struct refspec *refspec = &refs[i];
                const char *key = find_src ? refspec->dst : refspec->src;
                const char *value = find_src ? refspec->src : refspec->dst;
-               const char *needle = find_src ? query->dst : query->src;
-               char **result = find_src ? &query->src : &query->dst;
 
                if (!refspec->dst)
                        continue;
@@ -952,9 +986,9 @@ void sort_ref_list(struct ref **l, int (*cmp)(const void *, const void *))
        *l = llist_mergesort(*l, ref_list_get_next, ref_list_set_next, cmp);
 }
 
-static int count_refspec_match(const char *pattern,
-                              struct ref *refs,
-                              struct ref **matched_ref)
+int count_refspec_match(const char *pattern,
+                       struct ref *refs,
+                       struct ref **matched_ref)
 {
        int patlen = strlen(pattern);
        struct ref *matched_weak = NULL;
@@ -966,7 +1000,7 @@ static int count_refspec_match(const char *pattern,
                char *name = refs->name;
                int namelen = strlen(name);
 
-               if (!refname_match(pattern, name, ref_rev_parse_rules))
+               if (!refname_match(pattern, name))
                        continue;
 
                /* A match is "weak" if it is with refs outside
@@ -979,8 +1013,8 @@ static int count_refspec_match(const char *pattern,
                 */
                if (namelen != patlen &&
                    patlen != namelen - 5 &&
-                   prefixcmp(name, "refs/heads/") &&
-                   prefixcmp(name, "refs/tags/")) {
+                   !starts_with(name, "refs/heads/") &&
+                   !starts_with(name, "refs/tags/")) {
                        /* We want to catch the case where only weak
                         * matches are found and there are multiple
                         * matches, and where more than one strong
@@ -1051,9 +1085,9 @@ static char *guess_ref(const char *name, struct ref *peer)
        if (!r)
                return NULL;
 
-       if (!prefixcmp(r, "refs/heads/"))
+       if (starts_with(r, "refs/heads/"))
                strbuf_addstr(&buf, "refs/heads/");
-       else if (!prefixcmp(r, "refs/tags/"))
+       else if (starts_with(r, "refs/tags/"))
                strbuf_addstr(&buf, "refs/tags/");
        else
                return NULL;
@@ -1062,12 +1096,36 @@ static char *guess_ref(const char *name, struct ref *peer)
        return strbuf_detach(&buf, NULL);
 }
 
+static int match_explicit_lhs(struct ref *src,
+                             struct refspec *rs,
+                             struct ref **match,
+                             int *allocated_match)
+{
+       switch (count_refspec_match(rs->src, src, match)) {
+       case 1:
+               *allocated_match = 0;
+               return 0;
+       case 0:
+               /* The source could be in the get_sha1() format
+                * not a reference name.  :refs/other is a
+                * way to delete 'other' ref at the remote end.
+                */
+               *match = try_explicit_object_name(rs->src);
+               if (!*match)
+                       return error("src refspec %s does not match any.", rs->src);
+               *allocated_match = 1;
+               return 0;
+       default:
+               return error("src refspec %s matches more than one.", rs->src);
+       }
+}
+
 static int match_explicit(struct ref *src, struct ref *dst,
                          struct ref ***dst_tail,
                          struct refspec *rs)
 {
        struct ref *matched_src, *matched_dst;
-       int copy_src;
+       int allocated_src;
 
        const char *dst_value = rs->dst;
        char *dst_guess;
@@ -1076,23 +1134,8 @@ static int match_explicit(struct ref *src, struct ref *dst,
                return 0;
 
        matched_src = matched_dst = NULL;
-       switch (count_refspec_match(rs->src, src, &matched_src)) {
-       case 1:
-               copy_src = 1;
-               break;
-       case 0:
-               /* The source could be in the get_sha1() format
-                * not a reference name.  :refs/other is a
-                * way to delete 'other' ref at the remote end.
-                */
-               matched_src = try_explicit_object_name(rs->src);
-               if (!matched_src)
-                       return error("src refspec %s does not match any.", rs->src);
-               copy_src = 0;
-               break;
-       default:
-               return error("src refspec %s matches more than one.", rs->src);
-       }
+       if (match_explicit_lhs(src, rs, &matched_src, &allocated_src) < 0)
+               return -1;
 
        if (!dst_value) {
                unsigned char sha1[20];
@@ -1101,7 +1144,7 @@ static int match_explicit(struct ref *src, struct ref *dst,
                dst_value = resolve_ref_unsafe(matched_src->name, sha1, 1, &flag);
                if (!dst_value ||
                    ((flag & REF_ISSYMREF) &&
-                    prefixcmp(dst_value, "refs/heads/")))
+                    !starts_with(dst_value, "refs/heads/")))
                        die("%s cannot be resolved to branch.",
                            matched_src->name);
        }
@@ -1137,7 +1180,9 @@ static int match_explicit(struct ref *src, struct ref *dst,
                return error("dst ref %s receives from more than one src.",
                      matched_dst->name);
        else {
-               matched_dst->peer_ref = copy_src ? copy_ref(matched_src) : matched_src;
+               matched_dst->peer_ref = allocated_src ?
+                                       matched_src :
+                                       copy_ref(matched_src);
                matched_dst->force = rs->force;
        }
        return 0;
@@ -1190,7 +1235,7 @@ static char *get_ref_match(const struct refspec *rs, int rs_nr, const struct ref
                 * including refs outside refs/heads/ hierarchy, but
                 * that does not make much sense these days.
                 */
-               if (!send_mirror && prefixcmp(ref->name, "refs/heads/"))
+               if (!send_mirror && !starts_with(ref->name, "refs/heads/"))
                        return NULL;
                name = xstrdup(ref->name);
        }
@@ -1245,7 +1290,7 @@ static void add_missing_tags(struct ref *src, struct ref **dst, struct ref ***ds
                        add_to_tips(&sent_tips, ref->peer_ref->new_sha1);
                else
                        add_to_tips(&sent_tips, ref->old_sha1);
-               if (!prefixcmp(ref->name, "refs/tags/"))
+               if (starts_with(ref->name, "refs/tags/"))
                        string_list_append(&dst_tag, ref->name);
        }
        clear_commit_marks_many(sent_tips.nr, sent_tips.tip, TMP_MARK);
@@ -1254,7 +1299,7 @@ static void add_missing_tags(struct ref *src, struct ref **dst, struct ref ***ds
 
        /* Collect tags they do not have. */
        for (ref = src; ref; ref = ref->next) {
-               if (prefixcmp(ref->name, "refs/tags/"))
+               if (!starts_with(ref->name, "refs/tags/"))
                        continue; /* not a tag */
                if (string_list_has_string(&dst_tag, ref->name))
                        continue; /* they already have it */
@@ -1302,6 +1347,14 @@ static void add_missing_tags(struct ref *src, struct ref **dst, struct ref ***ds
        free(sent_tips.tip);
 }
 
+struct ref *find_ref_by_name(const struct ref *list, const char *name)
+{
+       for ( ; list; list = list->next)
+               if (!strcmp(list->name, name))
+                       return (struct ref *)list;
+       return NULL;
+}
+
 static void prepare_ref_index(struct string_list *ref_index, struct ref *ref)
 {
        for ( ; ref; ref = ref->next)
@@ -1411,12 +1464,13 @@ int match_push_refs(struct ref *src, struct ref **dst,
 }
 
 void set_ref_status_for_push(struct ref *remote_refs, int send_mirror,
-       int force_update)
+                            int force_update)
 {
        struct ref *ref;
 
        for (ref = remote_refs; ref; ref = ref->next) {
                int force_ref_update = ref->force || force_update;
+               int reject_reason = 0;
 
                if (ref->peer_ref)
                        hashcpy(ref->new_sha1, ref->peer_ref->new_sha1);
@@ -1431,6 +1485,26 @@ void set_ref_status_for_push(struct ref *remote_refs, int send_mirror,
                }
 
                /*
+                * Bypass the usual "must fast-forward" check but
+                * replace it with a weaker "the old value must be
+                * this value we observed".  If the remote ref has
+                * moved and is now different from what we expect,
+                * reject any push.
+                *
+                * It also is an error if the user told us to check
+                * with the remote-tracking branch to find the value
+                * to expect, but we did not have such a tracking
+                * branch.
+                */
+               if (ref->expect_old_sha1) {
+                       if (ref->expect_old_no_trackback ||
+                           hashcmp(ref->old_sha1, ref->old_sha1_expect))
+                               reject_reason = REF_STATUS_REJECT_STALE;
+               }
+
+               /*
+                * The usual "must fast-forward" rules.
+                *
                 * Decide whether an individual refspec A:B can be
                 * pushed.  The push will succeed if any of the
                 * following are true:
@@ -1448,24 +1522,26 @@ void set_ref_status_for_push(struct ref *remote_refs, int send_mirror,
                 *     passing the --force argument
                 */
 
-               if (!ref->deletion && !is_null_sha1(ref->old_sha1)) {
-                       int why = 0; /* why would this push require --force? */
-
-                       if (!prefixcmp(ref->name, "refs/tags/"))
-                               why = REF_STATUS_REJECT_ALREADY_EXISTS;
+               else if (!ref->deletion && !is_null_sha1(ref->old_sha1)) {
+                       if (starts_with(ref->name, "refs/tags/"))
+                               reject_reason = REF_STATUS_REJECT_ALREADY_EXISTS;
                        else if (!has_sha1_file(ref->old_sha1))
-                               why = REF_STATUS_REJECT_FETCH_FIRST;
+                               reject_reason = REF_STATUS_REJECT_FETCH_FIRST;
                        else if (!lookup_commit_reference_gently(ref->old_sha1, 1) ||
                                 !lookup_commit_reference_gently(ref->new_sha1, 1))
-                               why = REF_STATUS_REJECT_NEEDS_FORCE;
+                               reject_reason = REF_STATUS_REJECT_NEEDS_FORCE;
                        else if (!ref_newer(ref->new_sha1, ref->old_sha1))
-                               why = REF_STATUS_REJECT_NONFASTFORWARD;
-
-                       if (!force_ref_update)
-                               ref->status = why;
-                       else if (why)
-                               ref->forced_update = 1;
+                               reject_reason = REF_STATUS_REJECT_NONFASTFORWARD;
                }
+
+               /*
+                * "--force" will defeat any rejection implemented
+                * by the rules above.
+                */
+               if (!force_ref_update)
+                       ref->status = reject_reason;
+               else if (reject_reason)
+                       ref->forced_update = 1;
        }
 }
 
@@ -1506,7 +1582,7 @@ int branch_merge_matches(struct branch *branch,
 {
        if (!branch || i < 0 || i >= branch->merge_nr)
                return 0;
-       return refname_match(branch->merge[i]->src, refname, ref_fetch_rules);
+       return refname_match(branch->merge[i]->src, refname);
 }
 
 static int ignore_symref_update(const char *refname)
@@ -1519,6 +1595,13 @@ static int ignore_symref_update(const char *refname)
        return (flag & REF_ISSYMREF);
 }
 
+/*
+ * Create and return a list of (struct ref) consisting of copies of
+ * each remote_ref that matches refspec.  refspec must be a pattern.
+ * Fill in the copies' peer_ref to describe the local tracking refs to
+ * which they map.  Omit any references that would map to an existing
+ * local symbolic ref.
+ */
 static struct ref *get_expanded_map(const struct ref *remote_refs,
                                    const struct refspec *refspec)
 {
@@ -1526,9 +1609,9 @@ static struct ref *get_expanded_map(const struct ref *remote_refs,
        struct ref *ret = NULL;
        struct ref **tail = &ret;
 
-       char *expn_name;
-
        for (ref = remote_refs; ref; ref = ref->next) {
+               char *expn_name = NULL;
+
                if (strchr(ref->name, '^'))
                        continue; /* a dereference item */
                if (match_name_with_pattern(refspec->src, ref->name,
@@ -1537,12 +1620,12 @@ static struct ref *get_expanded_map(const struct ref *remote_refs,
                        struct ref *cpy = copy_ref(ref);
 
                        cpy->peer_ref = alloc_ref(expn_name);
-                       free(expn_name);
                        if (refspec->force)
                                cpy->peer_ref->force = 1;
                        *tail = cpy;
                        tail = &cpy->next;
                }
+               free(expn_name);
        }
 
        return ret;
@@ -1552,7 +1635,7 @@ static const struct ref *find_ref_by_name_abbrev(const struct ref *refs, const c
 {
        const struct ref *ref;
        for (ref = refs; ref; ref = ref->next) {
-               if (refname_match(name, ref->name, ref_fetch_rules))
+               if (refname_match(name, ref->name))
                        return ref;
        }
        return NULL;
@@ -1573,12 +1656,12 @@ static struct ref *get_local_ref(const char *name)
        if (!name || name[0] == '\0')
                return NULL;
 
-       if (!prefixcmp(name, "refs/"))
+       if (starts_with(name, "refs/"))
                return alloc_ref(name);
 
-       if (!prefixcmp(name, "heads/") ||
-           !prefixcmp(name, "tags/") ||
-           !prefixcmp(name, "remotes/"))
+       if (starts_with(name, "heads/") ||
+           starts_with(name, "tags/") ||
+           starts_with(name, "remotes/"))
                return alloc_ref_with_prefix("refs/", 5, name);
 
        return alloc_ref_with_prefix("refs/heads/", 11, name);
@@ -1613,7 +1696,7 @@ int get_fetch_map(const struct ref *remote_refs,
 
        for (rmp = &ref_map; *rmp; ) {
                if ((*rmp)->peer_ref) {
-                       if (prefixcmp((*rmp)->peer_ref->name, "refs/") ||
+                       if (!starts_with((*rmp)->peer_ref->name, "refs/") ||
                            check_refname_format((*rmp)->peer_ref->name, 0)) {
                                struct ref *ignore = *rmp;
                                error("* Ignoring funny ref '%s' locally",
@@ -1695,7 +1778,11 @@ int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1)
 }
 
 /*
- * Return true if there is anything to report, otherwise false.
+ * Compare a branch with its upstream, and save their differences (number
+ * of commits) in *num_ours and *num_theirs.
+ *
+ * Return 0 if branch has no upstream (no base), -1 if upstream is missing
+ * (with "gone" base), otherwise 1 (with base).
  */
 int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
 {
@@ -1706,34 +1793,30 @@ int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
        const char *rev_argv[10], *base;
        int rev_argc;
 
-       /*
-        * Nothing to report unless we are marked to build on top of
-        * somebody else.
-        */
+       /* Cannot stat unless we are marked to build on top of somebody else. */
        if (!branch ||
            !branch->merge || !branch->merge[0] || !branch->merge[0]->dst)
                return 0;
 
-       /*
-        * If what we used to build on no longer exists, there is
-        * nothing to report.
-        */
+       /* Cannot stat if what we used to build on no longer exists */
        base = branch->merge[0]->dst;
        if (read_ref(base, sha1))
-               return 0;
+               return -1;
        theirs = lookup_commit_reference(sha1);
        if (!theirs)
-               return 0;
+               return -1;
 
        if (read_ref(branch->refname, sha1))
-               return 0;
+               return -1;
        ours = lookup_commit_reference(sha1);
        if (!ours)
-               return 0;
+               return -1;
 
        /* are we the same? */
-       if (theirs == ours)
-               return 0;
+       if (theirs == ours) {
+               *num_theirs = *num_ours = 0;
+               return 1;
+       }
 
        /* Run "rev-list --left-right ours...theirs" internally... */
        rev_argc = 0;
@@ -1775,31 +1858,53 @@ int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
  */
 int format_tracking_info(struct branch *branch, struct strbuf *sb)
 {
-       int num_ours, num_theirs;
+       int ours, theirs;
        const char *base;
+       int upstream_is_gone = 0;
 
-       if (!stat_tracking_info(branch, &num_ours, &num_theirs))
+       switch (stat_tracking_info(branch, &ours, &theirs)) {
+       case 0:
+               /* no base */
                return 0;
+       case -1:
+               /* with "gone" base */
+               upstream_is_gone = 1;
+               break;
+       default:
+               /* with base */
+               break;
+       }
 
        base = branch->merge[0]->dst;
        base = shorten_unambiguous_ref(base, 0);
-       if (!num_theirs) {
+       if (upstream_is_gone) {
+               strbuf_addf(sb,
+                       _("Your branch is based on '%s', but the upstream is gone.\n"),
+                       base);
+               if (advice_status_hints)
+                       strbuf_addf(sb,
+                               _("  (use \"git branch --unset-upstream\" to fixup)\n"));
+       } else if (!ours && !theirs) {
+               strbuf_addf(sb,
+                       _("Your branch is up-to-date with '%s'.\n"),
+                       base);
+       } else if (!theirs) {
                strbuf_addf(sb,
                        Q_("Your branch is ahead of '%s' by %d commit.\n",
                           "Your branch is ahead of '%s' by %d commits.\n",
-                          num_ours),
-                       base, num_ours);
+                          ours),
+                       base, ours);
                if (advice_status_hints)
                        strbuf_addf(sb,
                                _("  (use \"git push\" to publish your local commits)\n"));
-       } else if (!num_ours) {
+       } else if (!ours) {
                strbuf_addf(sb,
                        Q_("Your branch is behind '%s' by %d commit, "
                               "and can be fast-forwarded.\n",
                           "Your branch is behind '%s' by %d commits, "
                               "and can be fast-forwarded.\n",
-                          num_theirs),
-                       base, num_theirs);
+                          theirs),
+                       base, theirs);
                if (advice_status_hints)
                        strbuf_addf(sb,
                                _("  (use \"git pull\" to update your local branch)\n"));
@@ -1811,8 +1916,8 @@ int format_tracking_info(struct branch *branch, struct strbuf *sb)
                           "Your branch and '%s' have diverged,\n"
                               "and have %d and %d different commits each, "
                               "respectively.\n",
-                          num_theirs),
-                       base, num_ours, num_theirs);
+                          theirs),
+                       base, ours, theirs);
                if (advice_status_hints)
                        strbuf_addf(sb,
                                _("  (use \"git pull\" to merge the remote branch into yours)\n"));
@@ -1875,7 +1980,7 @@ struct ref *guess_remote_head(const struct ref *head,
        /* Look for another ref that points there */
        for (r = refs; r; r = r->next) {
                if (r != head &&
-                   !prefixcmp(r->name, "refs/heads/") &&
+                   starts_with(r->name, "refs/heads/") &&
                    !hashcmp(r->old_sha1, head->old_sha1)) {
                        *tail = copy_ref(r);
                        tail = &((*tail)->next);
@@ -1936,3 +2041,121 @@ struct ref *get_stale_heads(struct refspec *refs, int ref_count, struct ref *fet
        string_list_clear(&ref_names, 0);
        return stale_refs;
 }
+
+/*
+ * Compare-and-swap
+ */
+void clear_cas_option(struct push_cas_option *cas)
+{
+       int i;
+
+       for (i = 0; i < cas->nr; i++)
+               free(cas->entry[i].refname);
+       free(cas->entry);
+       memset(cas, 0, sizeof(*cas));
+}
+
+static struct push_cas *add_cas_entry(struct push_cas_option *cas,
+                                     const char *refname,
+                                     size_t refnamelen)
+{
+       struct push_cas *entry;
+       ALLOC_GROW(cas->entry, cas->nr + 1, cas->alloc);
+       entry = &cas->entry[cas->nr++];
+       memset(entry, 0, sizeof(*entry));
+       entry->refname = xmemdupz(refname, refnamelen);
+       return entry;
+}
+
+int parse_push_cas_option(struct push_cas_option *cas, const char *arg, int unset)
+{
+       const char *colon;
+       struct push_cas *entry;
+
+       if (unset) {
+               /* "--no-<option>" */
+               clear_cas_option(cas);
+               return 0;
+       }
+
+       if (!arg) {
+               /* just "--<option>" */
+               cas->use_tracking_for_rest = 1;
+               return 0;
+       }
+
+       /* "--<option>=refname" or "--<option>=refname:value" */
+       colon = strchrnul(arg, ':');
+       entry = add_cas_entry(cas, arg, colon - arg);
+       if (!*colon)
+               entry->use_tracking = 1;
+       else if (get_sha1(colon + 1, entry->expect))
+               return error("cannot parse expected object name '%s'", colon + 1);
+       return 0;
+}
+
+int parseopt_push_cas_option(const struct option *opt, const char *arg, int unset)
+{
+       return parse_push_cas_option(opt->value, arg, unset);
+}
+
+int is_empty_cas(const struct push_cas_option *cas)
+{
+       return !cas->use_tracking_for_rest && !cas->nr;
+}
+
+/*
+ * Look at remote.fetch refspec and see if we have a remote
+ * tracking branch for the refname there.  Fill its current
+ * value in sha1[].
+ * If we cannot do so, return negative to signal an error.
+ */
+static int remote_tracking(struct remote *remote, const char *refname,
+                          unsigned char sha1[20])
+{
+       char *dst;
+
+       dst = apply_refspecs(remote->fetch, remote->fetch_refspec_nr, refname);
+       if (!dst)
+               return -1; /* no tracking ref for refname at remote */
+       if (read_ref(dst, sha1))
+               return -1; /* we know what the tracking ref is but we cannot read it */
+       return 0;
+}
+
+static void apply_cas(struct push_cas_option *cas,
+                     struct remote *remote,
+                     struct ref *ref)
+{
+       int i;
+
+       /* Find an explicit --<option>=<name>[:<value>] entry */
+       for (i = 0; i < cas->nr; i++) {
+               struct push_cas *entry = &cas->entry[i];
+               if (!refname_match(entry->refname, ref->name))
+                       continue;
+               ref->expect_old_sha1 = 1;
+               if (!entry->use_tracking)
+                       hashcpy(ref->old_sha1_expect, cas->entry[i].expect);
+               else if (remote_tracking(remote, ref->name, ref->old_sha1_expect))
+                       ref->expect_old_no_trackback = 1;
+               return;
+       }
+
+       /* Are we using "--<option>" to cover all? */
+       if (!cas->use_tracking_for_rest)
+               return;
+
+       ref->expect_old_sha1 = 1;
+       if (remote_tracking(remote, ref->name, ref->old_sha1_expect))
+               ref->expect_old_no_trackback = 1;
+}
+
+void apply_push_cas(struct push_cas_option *cas,
+                   struct remote *remote,
+                   struct ref *remote_refs)
+{
+       struct ref *ref;
+       for (ref = remote_refs; ref; ref = ref->next)
+               apply_cas(cas, remote, ref);
+}