Merge branch 'jc/maint-remove-renamed-ref' into maint
[git/git.git] / refs.c
diff --git a/refs.c b/refs.c
index ecfc22c..fb258ea 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -1,12 +1,12 @@
-#include "refs.h"
 #include "cache.h"
+#include "refs.h"
 #include "object.h"
 #include "tag.h"
-
-#include <errno.h>
+#include "dir.h"
 
 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
 #define REF_KNOWS_PEELED 04
+#define REF_BROKEN 010
 
 struct ref_list {
        struct ref_list *next;
@@ -49,22 +49,7 @@ static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
                                struct ref_list **new_entry)
 {
        int len;
-       struct ref_list **p = &list, *entry;
-
-       /* Find the place to insert the ref into.. */
-       while ((entry = *p) != NULL) {
-               int cmp = strcmp(entry->name, name);
-               if (cmp > 0)
-                       break;
-
-               /* Same as existing entry? */
-               if (!cmp) {
-                       if (new_entry)
-                               *new_entry = entry;
-                       return list;
-               }
-               p = &entry->next;
-       }
+       struct ref_list *entry;
 
        /* Allocate it and add it in.. */
        len = strlen(name) + 1;
@@ -73,23 +58,109 @@ static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
        hashclr(entry->peeled);
        memcpy(entry->name, name, len);
        entry->flag = flag;
-       entry->next = *p;
-       *p = entry;
+       entry->next = list;
        if (new_entry)
                *new_entry = entry;
-       return list;
+       return entry;
+}
+
+/* merge sort the ref list */
+static struct ref_list *sort_ref_list(struct ref_list *list)
+{
+       int psize, qsize, last_merge_count, cmp;
+       struct ref_list *p, *q, *l, *e;
+       struct ref_list *new_list = list;
+       int k = 1;
+       int merge_count = 0;
+
+       if (!list)
+               return list;
+
+       do {
+               last_merge_count = merge_count;
+               merge_count = 0;
+
+               psize = 0;
+
+               p = new_list;
+               q = new_list;
+               new_list = NULL;
+               l = NULL;
+
+               while (p) {
+                       merge_count++;
+
+                       while (psize < k && q->next) {
+                               q = q->next;
+                               psize++;
+                       }
+                       qsize = k;
+
+                       while ((psize > 0) || (qsize > 0 && q)) {
+                               if (qsize == 0 || !q) {
+                                       e = p;
+                                       p = p->next;
+                                       psize--;
+                               } else if (psize == 0) {
+                                       e = q;
+                                       q = q->next;
+                                       qsize--;
+                               } else {
+                                       cmp = strcmp(q->name, p->name);
+                                       if (cmp < 0) {
+                                               e = q;
+                                               q = q->next;
+                                               qsize--;
+                                       } else if (cmp > 0) {
+                                               e = p;
+                                               p = p->next;
+                                               psize--;
+                                       } else {
+                                               if (hashcmp(q->sha1, p->sha1))
+                                                       die("Duplicated ref, and SHA1s don't match: %s",
+                                                           q->name);
+                                               warning("Duplicated ref: %s", q->name);
+                                               e = q;
+                                               q = q->next;
+                                               qsize--;
+                                               free(e);
+                                               e = p;
+                                               p = p->next;
+                                               psize--;
+                                       }
+                               }
+
+                               e->next = NULL;
+
+                               if (l)
+                                       l->next = e;
+                               if (!new_list)
+                                       new_list = e;
+                               l = e;
+                       }
+
+                       p = q;
+               };
+
+               k = k * 2;
+       } while ((last_merge_count != merge_count) || (last_merge_count != 1));
+
+       return new_list;
 }
 
 /*
  * Future: need to be in "struct repository"
  * when doing a full libification.
  */
-struct cached_refs {
+static struct cached_refs {
        char did_loose;
        char did_packed;
        struct ref_list *loose;
        struct ref_list *packed;
-} cached_refs;
+} cached_refs, submodule_refs;
+static struct ref_list *current_ref;
+
+static struct ref_list *extra_refs;
 
 static void free_ref_list(struct ref_list *list)
 {
@@ -144,26 +215,59 @@ static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
                    !get_sha1_hex(refline + 1, sha1))
                        hashcpy(last->peeled, sha1);
        }
-       cached_refs->packed = list;
+       cached_refs->packed = sort_ref_list(list);
 }
 
-static struct ref_list *get_packed_refs(void)
+void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
 {
-       if (!cached_refs.did_packed) {
-               FILE *f = fopen(git_path("packed-refs"), "r");
-               cached_refs.packed = NULL;
+       extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
+}
+
+void clear_extra_refs(void)
+{
+       free_ref_list(extra_refs);
+       extra_refs = NULL;
+}
+
+static struct ref_list *get_packed_refs(const char *submodule)
+{
+       const char *packed_refs_file;
+       struct cached_refs *refs;
+
+       if (submodule) {
+               packed_refs_file = git_path_submodule(submodule, "packed-refs");
+               refs = &submodule_refs;
+               free_ref_list(refs->packed);
+       } else {
+               packed_refs_file = git_path("packed-refs");
+               refs = &cached_refs;
+       }
+
+       if (!refs->did_packed || submodule) {
+               FILE *f = fopen(packed_refs_file, "r");
+               refs->packed = NULL;
                if (f) {
-                       read_packed_refs(f, &cached_refs);
+                       read_packed_refs(f, refs);
                        fclose(f);
                }
-               cached_refs.did_packed = 1;
+               refs->did_packed = 1;
        }
-       return cached_refs.packed;
+       return refs->packed;
 }
 
-static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
+static struct ref_list *get_ref_dir(const char *submodule, const char *base,
+                                   struct ref_list *list)
 {
-       DIR *dir = opendir(git_path("%s", base));
+       DIR *dir;
+       const char *path;
+
+       if (submodule)
+               path = git_path_submodule(submodule, "%s", base);
+       else
+               path = git_path("%s", base);
+
+
+       dir = opendir(path);
 
        if (dir) {
                struct dirent *de;
@@ -179,6 +283,7 @@ static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
                        struct stat st;
                        int flag;
                        int namelen;
+                       const char *refdir;
 
                        if (de->d_name[0] == '.')
                                continue;
@@ -188,28 +293,79 @@ static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
                        if (has_extension(de->d_name, ".lock"))
                                continue;
                        memcpy(ref + baselen, de->d_name, namelen+1);
-                       if (stat(git_path("%s", ref), &st) < 0)
+                       refdir = submodule
+                               ? git_path_submodule(submodule, "%s", ref)
+                               : git_path("%s", ref);
+                       if (stat(refdir, &st) < 0)
                                continue;
                        if (S_ISDIR(st.st_mode)) {
-                               list = get_ref_dir(ref, list);
-                               continue;
-                       }
-                       if (!resolve_ref(ref, sha1, 1, &flag)) {
-                               error("%s points nowhere!", ref);
+                               list = get_ref_dir(submodule, ref, list);
                                continue;
                        }
+                       if (submodule) {
+                               hashclr(sha1);
+                               flag = 0;
+                               if (resolve_gitlink_ref(submodule, ref, sha1) < 0) {
+                                       hashclr(sha1);
+                                       flag |= REF_BROKEN;
+                               }
+                       } else
+                               if (!resolve_ref(ref, sha1, 1, &flag)) {
+                                       hashclr(sha1);
+                                       flag |= REF_BROKEN;
+                               }
                        list = add_ref(ref, sha1, flag, list, NULL);
                }
                free(ref);
                closedir(dir);
        }
-       return list;
+       return sort_ref_list(list);
+}
+
+struct warn_if_dangling_data {
+       FILE *fp;
+       const char *refname;
+       const char *msg_fmt;
+};
+
+static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
+                                  int flags, void *cb_data)
+{
+       struct warn_if_dangling_data *d = cb_data;
+       const char *resolves_to;
+       unsigned char junk[20];
+
+       if (!(flags & REF_ISSYMREF))
+               return 0;
+
+       resolves_to = resolve_ref(refname, junk, 0, NULL);
+       if (!resolves_to || strcmp(resolves_to, d->refname))
+               return 0;
+
+       fprintf(d->fp, d->msg_fmt, refname);
+       return 0;
+}
+
+void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
+{
+       struct warn_if_dangling_data data;
+
+       data.fp = fp;
+       data.refname = refname;
+       data.msg_fmt = msg_fmt;
+       for_each_rawref(warn_if_dangling_symref, &data);
 }
 
-static struct ref_list *get_loose_refs(void)
+static struct ref_list *get_loose_refs(const char *submodule)
 {
+       if (submodule) {
+               free_ref_list(submodule_refs.loose);
+               submodule_refs.loose = get_ref_dir(submodule, "refs", NULL);
+               return submodule_refs.loose;
+       }
+
        if (!cached_refs.did_loose) {
-               cached_refs.loose = get_ref_dir("refs", NULL);
+               cached_refs.loose = get_ref_dir(NULL, "refs", NULL);
                cached_refs.did_loose = 1;
        }
        return cached_refs.loose;
@@ -217,10 +373,114 @@ static struct ref_list *get_loose_refs(void)
 
 /* We allow "recursive" symbolic refs. Only within reason, though */
 #define MAXDEPTH 5
+#define MAXREFLEN (1024)
+
+static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
+{
+       FILE *f;
+       struct cached_refs refs;
+       struct ref_list *ref;
+       int retval;
 
+       strcpy(name + pathlen, "packed-refs");
+       f = fopen(name, "r");
+       if (!f)
+               return -1;
+       read_packed_refs(f, &refs);
+       fclose(f);
+       ref = refs.packed;
+       retval = -1;
+       while (ref) {
+               if (!strcmp(ref->name, refname)) {
+                       retval = 0;
+                       memcpy(result, ref->sha1, 20);
+                       break;
+               }
+               ref = ref->next;
+       }
+       free_ref_list(refs.packed);
+       return retval;
+}
+
+static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
+{
+       int fd, len = strlen(refname);
+       char buffer[128], *p;
+
+       if (recursion > MAXDEPTH || len > MAXREFLEN)
+               return -1;
+       memcpy(name + pathlen, refname, len+1);
+       fd = open(name, O_RDONLY);
+       if (fd < 0)
+               return resolve_gitlink_packed_ref(name, pathlen, refname, result);
+
+       len = read(fd, buffer, sizeof(buffer)-1);
+       close(fd);
+       if (len < 0)
+               return -1;
+       while (len && isspace(buffer[len-1]))
+               len--;
+       buffer[len] = 0;
+
+       /* Was it a detached head or an old-fashioned symlink? */
+       if (!get_sha1_hex(buffer, result))
+               return 0;
+
+       /* Symref? */
+       if (strncmp(buffer, "ref:", 4))
+               return -1;
+       p = buffer + 4;
+       while (isspace(*p))
+               p++;
+
+       return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
+}
+
+int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
+{
+       int len = strlen(path), retval;
+       char *gitdir;
+       const char *tmp;
+
+       while (len && path[len-1] == '/')
+               len--;
+       if (!len)
+               return -1;
+       gitdir = xmalloc(len + MAXREFLEN + 8);
+       memcpy(gitdir, path, len);
+       memcpy(gitdir + len, "/.git", 6);
+       len += 5;
+
+       tmp = read_gitfile(gitdir);
+       if (tmp) {
+               free(gitdir);
+               len = strlen(tmp);
+               gitdir = xmalloc(len + MAXREFLEN + 3);
+               memcpy(gitdir, tmp, len);
+       }
+       gitdir[len] = '/';
+       gitdir[++len] = '\0';
+       retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
+       free(gitdir);
+       return retval;
+}
+
+/*
+ * If the "reading" argument is set, this function finds out what _object_
+ * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
+ * has to exist, and if it is symbolic, it has to point at an existing ref,
+ * because the "read" goes through the symref to the ref it points at.
+ *
+ * The access that is not "reading" may often be "writing", but does not
+ * have to; it can be merely checking _where it leads to_. If it is a
+ * prelude to "writing" to the ref, a write to a symref that points at
+ * yet-to-be-born ref will create the real ref pointed by the symref.
+ * reading=0 allows the caller to check where such a symref leads to.
+ */
 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 {
-       int depth = MAXDEPTH, len;
+       int depth = MAXDEPTH;
+       ssize_t len;
        char buffer[256];
        static char ref_buffer[256];
 
@@ -228,7 +488,7 @@ const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *
                *flag = 0;
 
        for (;;) {
-               const char *path = git_path("%s", ref);
+               char path[PATH_MAX];
                struct stat st;
                char *buf;
                int fd;
@@ -236,15 +496,10 @@ const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *
                if (--depth < 0)
                        return NULL;
 
-               /* Special case: non-existing file.
-                * Not having the refs/heads/new-branch is OK
-                * if we are writing into it, so is .git/HEAD
-                * that points at refs/heads/master still to be
-                * born.  It is NOT OK if we are resolving for
-                * reading.
-                */
+               git_snpath(path, sizeof(path), "%s", ref);
+               /* Special case: non-existing file. */
                if (lstat(path, &st) < 0) {
-                       struct ref_list *list = get_packed_refs();
+                       struct ref_list *list = get_packed_refs(NULL);
                        while (list) {
                                if (!strcmp(ref, list->name)) {
                                        hashcpy(sha1, list->sha1);
@@ -286,7 +541,7 @@ const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *
                fd = open(path, O_RDONLY);
                if (fd < 0)
                        return NULL;
-               len = read(fd, buffer, sizeof(buffer)-1);
+               len = read_in_full(fd, buffer, sizeof(buffer)-1);
                close(fd);
 
                /*
@@ -311,48 +566,12 @@ const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *
        return ref;
 }
 
-int create_symref(const char *ref_target, const char *refs_heads_master)
-{
-       const char *lockpath;
-       char ref[1000];
-       int fd, len, written;
-       const char *git_HEAD = git_path("%s", ref_target);
-
-#ifndef NO_SYMLINK_HEAD
-       if (prefer_symlink_refs) {
-               unlink(git_HEAD);
-               if (!symlink(refs_heads_master, git_HEAD))
-                       return 0;
-               fprintf(stderr, "no symlink - falling back to symbolic ref\n");
-       }
-#endif
-
-       len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
-       if (sizeof(ref) <= len) {
-               error("refname too long: %s", refs_heads_master);
-               return -1;
-       }
-       lockpath = mkpath("%s.lock", git_HEAD);
-       fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666); 
-       written = write(fd, ref, len);
-       close(fd);
-       if (written != len) {
-               unlink(lockpath);
-               error("Unable to write to %s", lockpath);
-               return -2;
-       }
-       if (rename(lockpath, git_HEAD) < 0) {
-               unlink(lockpath);
-               error("Unable to create %s", git_HEAD);
-               return -3;
-       }
-       if (adjust_shared_perm(git_HEAD)) {
-               unlink(lockpath);
-               error("Unable to fix permissions on %s", lockpath);
-               return -4;
-       }
-       return 0;
-}
+/* The argument to filter_refs */
+struct ref_filter {
+       const char *pattern;
+       each_ref_fn *fn;
+       void *cb_data;
+};
 
 int read_ref(const char *ref, unsigned char *sha1)
 {
@@ -361,31 +580,55 @@ int read_ref(const char *ref, unsigned char *sha1)
        return -1;
 }
 
+#define DO_FOR_EACH_INCLUDE_BROKEN 01
 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
-                     void *cb_data, struct ref_list *entry)
+                     int flags, void *cb_data, struct ref_list *entry)
 {
-       if (strncmp(base, entry->name, trim))
-               return 0;
-       if (is_null_sha1(entry->sha1))
-               return 0;
-       if (!has_sha1_file(entry->sha1)) {
-               error("%s does not point to a valid object!", entry->name);
+       if (prefixcmp(entry->name, base))
                return 0;
+
+       if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
+               if (entry->flag & REF_BROKEN)
+                       return 0; /* ignore dangling symref */
+               if (!has_sha1_file(entry->sha1)) {
+                       error("%s does not point to a valid object!", entry->name);
+                       return 0;
+               }
        }
+       current_ref = entry;
        return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 }
 
+static int filter_refs(const char *ref, const unsigned char *sha, int flags,
+       void *data)
+{
+       struct ref_filter *filter = (struct ref_filter *)data;
+       if (fnmatch(filter->pattern, ref, 0))
+               return 0;
+       return filter->fn(ref, sha, flags, filter->cb_data);
+}
+
 int peel_ref(const char *ref, unsigned char *sha1)
 {
        int flag;
        unsigned char base[20];
        struct object *o;
 
+       if (current_ref && (current_ref->name == ref
+               || !strcmp(current_ref->name, ref))) {
+               if (current_ref->flag & REF_KNOWS_PEELED) {
+                       hashcpy(sha1, current_ref->peeled);
+                       return 0;
+               }
+               hashcpy(base, current_ref->sha1);
+               goto fallback;
+       }
+
        if (!resolve_ref(ref, base, 1, &flag))
                return -1;
 
        if ((flag & REF_ISPACKED)) {
-               struct ref_list *list = get_packed_refs();
+               struct ref_list *list = get_packed_refs(NULL);
 
                while (list) {
                        if (!strcmp(list->name, ref)) {
@@ -400,9 +643,9 @@ int peel_ref(const char *ref, unsigned char *sha1)
                }
        }
 
-       /* fallback - callers should not call this for unpacked refs */
+fallback:
        o = parse_object(base);
-       if (o->type == OBJ_TAG) {
+       if (o && o->type == OBJ_TAG) {
                o = deref_tag(o, ref, 0);
                if (o) {
                        hashcpy(sha1, o->sha1);
@@ -412,12 +655,17 @@ int peel_ref(const char *ref, unsigned char *sha1)
        return -1;
 }
 
-static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
-                          void *cb_data)
+static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
+                          int trim, int flags, void *cb_data)
 {
-       int retval;
-       struct ref_list *packed = get_packed_refs();
-       struct ref_list *loose = get_loose_refs();
+       int retval = 0;
+       struct ref_list *packed = get_packed_refs(submodule);
+       struct ref_list *loose = get_loose_refs(submodule);
+
+       struct ref_list *extra;
+
+       for (extra = extra_refs; extra; extra = extra->next)
+               retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 
        while (packed && loose) {
                struct ref_list *entry;
@@ -433,59 +681,171 @@ static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
                        entry = packed;
                        packed = packed->next;
                }
-               retval = do_one_ref(base, fn, trim, cb_data, entry);
+               retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
                if (retval)
-                       return retval;
+                       goto end_each;
        }
 
        for (packed = packed ? packed : loose; packed; packed = packed->next) {
-               retval = do_one_ref(base, fn, trim, cb_data, packed);
+               retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
                if (retval)
-                       return retval;
+                       goto end_each;
        }
-       return 0;
+
+end_each:
+       current_ref = NULL;
+       return retval;
 }
 
-int head_ref(each_ref_fn fn, void *cb_data)
+
+static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 {
        unsigned char sha1[20];
        int flag;
 
+       if (submodule) {
+               if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
+                       return fn("HEAD", sha1, 0, cb_data);
+
+               return 0;
+       }
+
        if (resolve_ref("HEAD", sha1, 1, &flag))
                return fn("HEAD", sha1, flag, cb_data);
+
        return 0;
 }
 
+int head_ref(each_ref_fn fn, void *cb_data)
+{
+       return do_head_ref(NULL, fn, cb_data);
+}
+
+int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+       return do_head_ref(submodule, fn, cb_data);
+}
+
 int for_each_ref(each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref("refs/", fn, 0, cb_data);
+       return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
+}
+
+int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+       return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
+}
+
+int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
+{
+       return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
+}
+
+int for_each_ref_in_submodule(const char *submodule, const char *prefix,
+               each_ref_fn fn, void *cb_data)
+{
+       return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
 }
 
 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref("refs/tags/", fn, 10, cb_data);
+       return for_each_ref_in("refs/tags/", fn, cb_data);
+}
+
+int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+       return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 }
 
 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref("refs/heads/", fn, 11, cb_data);
+       return for_each_ref_in("refs/heads/", fn, cb_data);
+}
+
+int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+       return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 }
 
 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 {
-       return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
+       return for_each_ref_in("refs/remotes/", fn, cb_data);
 }
 
-/* NEEDSWORK: This is only used by ssh-upload and it should go; the
- * caller should do resolve_ref or read_ref like everybody else.  Or
- * maybe everybody else should use get_ref_sha1() instead of doing
- * read_ref().
- */
-int get_ref_sha1(const char *ref, unsigned char *sha1)
+int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-       if (check_ref_format(ref))
-               return -1;
-       return read_ref(mkpath("refs/%s", ref), sha1);
+       return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
+}
+
+int for_each_replace_ref(each_ref_fn fn, void *cb_data)
+{
+       return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
+}
+
+int head_ref_namespaced(each_ref_fn fn, void *cb_data)
+{
+       struct strbuf buf = STRBUF_INIT;
+       int ret = 0;
+       unsigned char sha1[20];
+       int flag;
+
+       strbuf_addf(&buf, "%sHEAD", get_git_namespace());
+       if (resolve_ref(buf.buf, sha1, 1, &flag))
+               ret = fn(buf.buf, sha1, flag, cb_data);
+       strbuf_release(&buf);
+
+       return ret;
+}
+
+int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
+{
+       struct strbuf buf = STRBUF_INIT;
+       int ret;
+       strbuf_addf(&buf, "%srefs/", get_git_namespace());
+       ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
+       strbuf_release(&buf);
+       return ret;
+}
+
+int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
+       const char *prefix, void *cb_data)
+{
+       struct strbuf real_pattern = STRBUF_INIT;
+       struct ref_filter filter;
+       int ret;
+
+       if (!prefix && prefixcmp(pattern, "refs/"))
+               strbuf_addstr(&real_pattern, "refs/");
+       else if (prefix)
+               strbuf_addstr(&real_pattern, prefix);
+       strbuf_addstr(&real_pattern, pattern);
+
+       if (!has_glob_specials(pattern)) {
+               /* Append implied '/' '*' if not present. */
+               if (real_pattern.buf[real_pattern.len - 1] != '/')
+                       strbuf_addch(&real_pattern, '/');
+               /* No need to check for '*', there is none. */
+               strbuf_addch(&real_pattern, '*');
+       }
+
+       filter.pattern = real_pattern.buf;
+       filter.fn = fn;
+       filter.cb_data = cb_data;
+       ret = for_each_ref(filter_refs, &filter);
+
+       strbuf_release(&real_pattern);
+       return ret;
+}
+
+int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
+{
+       return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
+}
+
+int for_each_rawref(each_ref_fn fn, void *cb_data)
+{
+       return do_for_each_ref(NULL, "", fn, 0,
+                              DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 }
 
 /*
@@ -496,19 +856,27 @@ int get_ref_sha1(const char *ref, unsigned char *sha1)
  * - it has double dots "..", or
  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
  * - it ends with a "/".
+ * - it ends with ".lock"
+ * - it contains a "\" (backslash)
  */
 
 static inline int bad_ref_char(int ch)
 {
-       return (((unsigned) ch) <= ' ' ||
-               ch == '~' || ch == '^' || ch == ':' ||
-               /* 2.13 Pattern Matching Notation */
-               ch == '?' || ch == '*' || ch == '[');
+       if (((unsigned) ch) <= ' ' || ch == 0x7f ||
+           ch == '~' || ch == '^' || ch == ':' || ch == '\\')
+               return 1;
+       /* 2.13 Pattern Matching Notation */
+       if (ch == '?' || ch == '[') /* Unsupported */
+               return 1;
+       if (ch == '*') /* Supported at the end */
+               return 2;
+       return 0;
 }
 
 int check_ref_format(const char *ref)
 {
-       int ch, level;
+       int ch, level, bad_type, last;
+       int ret = CHECK_REF_FORMAT_OK;
        const char *cp = ref;
 
        level = 0;
@@ -516,28 +884,86 @@ int check_ref_format(const char *ref)
                while ((ch = *cp++) == '/')
                        ; /* tolerate duplicated slashes */
                if (!ch)
-                       return -1; /* should not end with slashes */
+                       /* should not end with slashes */
+                       return CHECK_REF_FORMAT_ERROR;
 
                /* we are at the beginning of the path component */
-               if (ch == '.' || bad_ref_char(ch))
-                       return -1;
+               if (ch == '.')
+                       return CHECK_REF_FORMAT_ERROR;
+               bad_type = bad_ref_char(ch);
+               if (bad_type) {
+                       if (bad_type == 2 && (!*cp || *cp == '/') &&
+                           ret == CHECK_REF_FORMAT_OK)
+                               ret = CHECK_REF_FORMAT_WILDCARD;
+                       else
+                               return CHECK_REF_FORMAT_ERROR;
+               }
 
+               last = ch;
                /* scan the rest of the path component */
                while ((ch = *cp++) != 0) {
-                       if (bad_ref_char(ch))
-                               return -1;
+                       bad_type = bad_ref_char(ch);
+                       if (bad_type)
+                               return CHECK_REF_FORMAT_ERROR;
                        if (ch == '/')
                                break;
-                       if (ch == '.' && *cp == '.')
-                               return -1;
+                       if (last == '.' && ch == '.')
+                               return CHECK_REF_FORMAT_ERROR;
+                       if (last == '@' && ch == '{')
+                               return CHECK_REF_FORMAT_ERROR;
+                       last = ch;
                }
                level++;
                if (!ch) {
+                       if (ref <= cp - 2 && cp[-2] == '.')
+                               return CHECK_REF_FORMAT_ERROR;
                        if (level < 2)
-                               return -1; /* at least of form "heads/blah" */
-                       return 0;
+                               return CHECK_REF_FORMAT_ONELEVEL;
+                       if (has_extension(ref, ".lock"))
+                               return CHECK_REF_FORMAT_ERROR;
+                       return ret;
+               }
+       }
+}
+
+const char *prettify_refname(const char *name)
+{
+       return name + (
+               !prefixcmp(name, "refs/heads/") ? 11 :
+               !prefixcmp(name, "refs/tags/") ? 10 :
+               !prefixcmp(name, "refs/remotes/") ? 13 :
+               0);
+}
+
+const char *ref_rev_parse_rules[] = {
+       "%.*s",
+       "refs/%.*s",
+       "refs/tags/%.*s",
+       "refs/heads/%.*s",
+       "refs/remotes/%.*s",
+       "refs/remotes/%.*s/HEAD",
+       NULL
+};
+
+const char *ref_fetch_rules[] = {
+       "%.*s",
+       "refs/%.*s",
+       "refs/heads/%.*s",
+       NULL
+};
+
+int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
+{
+       const char **p;
+       const int abbrev_name_len = strlen(abbrev_name);
+
+       for (p = rules; *p; p++) {
+               if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
+                       return 1;
                }
        }
+
+       return 0;
 }
 
 static struct ref_lock *verify_lock(struct ref_lock *lock,
@@ -557,57 +983,23 @@ static struct ref_lock *verify_lock(struct ref_lock *lock,
        return lock;
 }
 
-static int remove_empty_dir_recursive(char *path, int len)
-{
-       DIR *dir = opendir(path);
-       struct dirent *e;
-       int ret = 0;
-
-       if (!dir)
-               return -1;
-       if (path[len-1] != '/')
-               path[len++] = '/';
-       while ((e = readdir(dir)) != NULL) {
-               struct stat st;
-               int namlen;
-               if ((e->d_name[0] == '.') &&
-                   ((e->d_name[1] == 0) ||
-                    ((e->d_name[1] == '.') && e->d_name[2] == 0)))
-                       continue; /* "." and ".." */
-
-               namlen = strlen(e->d_name);
-               if ((len + namlen < PATH_MAX) &&
-                   strcpy(path + len, e->d_name) &&
-                   !lstat(path, &st) &&
-                   S_ISDIR(st.st_mode) &&
-                   !remove_empty_dir_recursive(path, len + namlen))
-                       continue; /* happy */
-
-               /* path too long, stat fails, or non-directory still exists */
-               ret = -1;
-               break;
-       }
-       closedir(dir);
-       if (!ret) {
-               path[len] = 0;
-               ret = rmdir(path);
-       }
-       return ret;
-}
-
-static int remove_empty_directories(char *file)
+static int remove_empty_directories(const char *file)
 {
        /* we want to create a file but there is a directory there;
         * if that is an empty directory (or a directory that contains
         * only empty directories), remove them.
         */
-       char path[PATH_MAX];
-       int len = strlen(file);
+       struct strbuf path;
+       int result;
 
-       if (len >= PATH_MAX) /* path too long ;-) */
-               return -1;
-       strcpy(path, file);
-       return remove_empty_dir_recursive(path, len);
+       strbuf_init(&path, 20);
+       strbuf_addstr(&path, file);
+
+       result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
+
+       strbuf_release(&path);
+
+       return result;
 }
 
 static int is_refname_available(const char *ref, const char *oldref,
@@ -633,19 +1025,20 @@ static int is_refname_available(const char *ref, const char *oldref,
        return 1;
 }
 
-static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int *flag)
+static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
 {
        char *ref_file;
        const char *orig_ref = ref;
        struct ref_lock *lock;
-       struct stat st;
        int last_errno = 0;
+       int type, lflags;
        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
+       int missing = 0;
 
        lock = xcalloc(1, sizeof(struct ref_lock));
        lock->lock_fd = -1;
 
-       ref = resolve_ref(ref, lock->old_sha1, mustexist, flag);
+       ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
        if (!ref && errno == EISDIR) {
                /* we are trying to lock foo but we used to
                 * have foo/bar which now does not exist;
@@ -658,37 +1051,50 @@ static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char
                        error("there are still refs under '%s'", orig_ref);
                        goto error_return;
                }
-               ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, flag);
+               ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
        }
+       if (type_p)
+           *type_p = type;
        if (!ref) {
                last_errno = errno;
                error("unable to resolve reference %s: %s",
                        orig_ref, strerror(errno));
                goto error_return;
        }
+       missing = is_null_sha1(lock->old_sha1);
        /* When the ref did not exist and we are creating it,
         * make sure there is no existing ref that is packed
         * whose name begins with our refname, nor a ref whose
         * name is a proper prefix of our refname.
         */
-       if (is_null_sha1(lock->old_sha1) &&
-            !is_refname_available(ref, NULL, get_packed_refs(), 0))
+       if (missing &&
+            !is_refname_available(ref, NULL, get_packed_refs(NULL), 0)) {
+               last_errno = ENOTDIR;
                goto error_return;
+       }
 
        lock->lk = xcalloc(1, sizeof(struct lock_file));
 
+       lflags = LOCK_DIE_ON_ERROR;
+       if (flags & REF_NODEREF) {
+               ref = orig_ref;
+               lflags |= LOCK_NODEREF;
+       }
        lock->ref_name = xstrdup(ref);
-       lock->log_file = xstrdup(git_path("logs/%s", ref));
+       lock->orig_ref_name = xstrdup(orig_ref);
        ref_file = git_path("%s", ref);
-       lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
+       if (missing)
+               lock->force_write = 1;
+       if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
+               lock->force_write = 1;
 
        if (safe_create_leading_directories(ref_file)) {
                last_errno = errno;
                error("unable to create directory for %s", ref_file);
                goto error_return;
        }
-       lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
 
+       lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 
  error_return:
@@ -703,12 +1109,18 @@ struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
        if (check_ref_format(ref))
                return NULL;
        strcpy(refpath, mkpath("refs/%s", ref));
-       return lock_ref_sha1_basic(refpath, old_sha1, NULL);
+       return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
 }
 
-struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1)
+struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
 {
-       return lock_ref_sha1_basic(ref, old_sha1, NULL);
+       switch (check_ref_format(ref)) {
+       default:
+               return NULL;
+       case 0:
+       case CHECK_REF_FORMAT_ONELEVEL:
+               return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
+       }
 }
 
 static struct lock_file packlock;
@@ -719,7 +1131,7 @@ static int repack_without_ref(const char *refname)
        int fd;
        int found = 0;
 
-       packed_ref_list = get_packed_refs();
+       packed_ref_list = get_packed_refs(NULL);
        for (list = packed_ref_list; list; list = list->next) {
                if (!strcmp(refname, list->name)) {
                        found = 1;
@@ -728,10 +1140,11 @@ static int repack_without_ref(const char *refname)
        }
        if (!found)
                return 0;
-       memset(&packlock, 0, sizeof(packlock));
        fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
-       if (fd < 0)
+       if (fd < 0) {
+               unable_to_lock_error(git_path("packed-refs"), errno);
                return error("cannot delete '%s' from packed refs", refname);
+       }
 
        for (list = packed_ref_list; list; list = list->next) {
                char line[PATH_MAX + 100];
@@ -749,25 +1162,31 @@ static int repack_without_ref(const char *refname)
        return commit_lock_file(&packlock);
 }
 
-int delete_ref(const char *refname, unsigned char *sha1)
+int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 {
        struct ref_lock *lock;
-       int err, i, ret = 0, flag = 0;
+       int err, i = 0, ret = 0, flag = 0;
 
-       lock = lock_ref_sha1_basic(refname, sha1, &flag);
+       lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
        if (!lock)
                return 1;
-       if (!(flag & REF_ISPACKED)) {
+       if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
                /* loose */
-               i = strlen(lock->lk->filename) - 5; /* .lock */
-               lock->lk->filename[i] = 0;
-               err = unlink(lock->lk->filename);
-               if (err) {
-                       ret = 1;
-                       error("unlink(%s) failed: %s",
-                             lock->lk->filename, strerror(errno));
+               const char *path;
+
+               if (!(delopt & REF_NODEREF)) {
+                       i = strlen(lock->lk->filename) - 5; /* .lock */
+                       lock->lk->filename[i] = 0;
+                       path = lock->lk->filename;
+               } else {
+                       path = git_path("%s", refname);
                }
-               lock->lk->filename[i] = '.';
+               err = unlink_or_warn(path);
+               if (err && errno != ENOENT)
+                       ret = 1;
+
+               if (!(delopt & REF_NODEREF))
+                       lock->lk->filename[i] = '.';
        }
        /* removing the loose one could have resurrected an earlier
         * packed one.  Also, if it was not loose we need to repack
@@ -775,49 +1194,56 @@ int delete_ref(const char *refname, unsigned char *sha1)
         */
        ret |= repack_without_ref(refname);
 
-       err = unlink(lock->log_file);
-       if (err && errno != ENOENT)
-               fprintf(stderr, "warning: unlink(%s) failed: %s",
-                       lock->log_file, strerror(errno));
+       unlink_or_warn(git_path("logs/%s", lock->ref_name));
        invalidate_cached_refs();
        unlock_ref(lock);
        return ret;
 }
 
-int rename_ref(const char *oldref, const char *newref)
+/*
+ * People using contrib's git-new-workdir have .git/logs/refs ->
+ * /some/other/path/.git/logs/refs, and that may live on another device.
+ *
+ * IOW, to avoid cross device rename errors, the temporary renamed log must
+ * live into logs/refs.
+ */
+#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
+
+int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 {
        unsigned char sha1[20], orig_sha1[20];
        int flag = 0, logmoved = 0;
        struct ref_lock *lock;
-       char msg[PATH_MAX*2 + 100];
        struct stat loginfo;
-       int log = !stat(git_path("logs/%s", oldref), &loginfo);
+       int log = !lstat(git_path("logs/%s", oldref), &loginfo);
+       const char *symref = NULL;
 
-       if (S_ISLNK(loginfo.st_mode))
+       if (log && S_ISLNK(loginfo.st_mode))
                return error("reflog for %s is a symlink", oldref);
 
-       if (!resolve_ref(oldref, orig_sha1, 1, &flag))
+       symref = resolve_ref(oldref, orig_sha1, 1, &flag);
+       if (flag & REF_ISSYMREF)
+               return error("refname %s is a symbolic ref, renaming it is not supported",
+                       oldref);
+       if (!symref)
                return error("refname %s not found", oldref);
 
-       if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
+       if (!is_refname_available(newref, oldref, get_packed_refs(NULL), 0))
                return 1;
 
-       if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
+       if (!is_refname_available(newref, oldref, get_loose_refs(NULL), 0))
                return 1;
 
-       if (snprintf(msg, sizeof(msg), "renamed %s to %s", oldref, newref) > sizeof(msg))
-               return error("Refnames to long");
-
-       if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
-               return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
+       if (log && rename(git_path("logs/%s", oldref), git_path(TMP_RENAMED_LOG)))
+               return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
                        oldref, strerror(errno));
 
-       if (delete_ref(oldref, orig_sha1)) {
+       if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
                error("unable to delete old %s", oldref);
                goto rollback;
        }
 
-       if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1)) {
+       if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
                if (errno==EISDIR) {
                        if (remove_empty_directories(git_path("%s", newref))) {
                                error("Directory not empty: %s", newref);
@@ -835,30 +1261,34 @@ int rename_ref(const char *oldref, const char *newref)
        }
 
  retry:
-       if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
-               if (errno==EISDIR) {
+       if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newref))) {
+               if (errno==EISDIR || errno==ENOTDIR) {
+                       /*
+                        * rename(a, b) when b is an existing
+                        * directory ought to result in ISDIR, but
+                        * Solaris 5.8 gives ENOTDIR.  Sheesh.
+                        */
                        if (remove_empty_directories(git_path("logs/%s", newref))) {
                                error("Directory not empty: logs/%s", newref);
                                goto rollback;
                        }
                        goto retry;
                } else {
-                       error("unable to move logfile tmp-renamed-log to logs/%s: %s",
+                       error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
                                newref, strerror(errno));
                        goto rollback;
                }
        }
        logmoved = log;
 
-       lock = lock_ref_sha1_basic(newref, NULL, NULL);
+       lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
        if (!lock) {
                error("unable to lock %s for update", newref);
                goto rollback;
        }
-
        lock->force_write = 1;
        hashcpy(lock->old_sha1, orig_sha1);
-       if (write_ref_sha1(lock, orig_sha1, msg)) {
+       if (write_ref_sha1(lock, orig_sha1, logmsg)) {
                error("unable to write current sha1 into %s", newref);
                goto rollback;
        }
@@ -866,7 +1296,7 @@ int rename_ref(const char *oldref, const char *newref)
        return 0;
 
  rollback:
-       lock = lock_ref_sha1_basic(oldref, NULL, NULL);
+       lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
        if (!lock) {
                error("unable to lock %s for rollback", oldref);
                goto rollbacklog;
@@ -884,90 +1314,151 @@ int rename_ref(const char *oldref, const char *newref)
                error("unable to restore logfile %s from %s: %s",
                        oldref, newref, strerror(errno));
        if (!logmoved && log &&
-           rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
-               error("unable to restore logfile %s from tmp-renamed-log: %s",
+           rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldref)))
+               error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
                        oldref, strerror(errno));
 
        return 1;
 }
 
+int close_ref(struct ref_lock *lock)
+{
+       if (close_lock_file(lock->lk))
+               return -1;
+       lock->lock_fd = -1;
+       return 0;
+}
+
+int commit_ref(struct ref_lock *lock)
+{
+       if (commit_lock_file(lock->lk))
+               return -1;
+       lock->lock_fd = -1;
+       return 0;
+}
+
 void unlock_ref(struct ref_lock *lock)
 {
-       if (lock->lock_fd >= 0) {
-               close(lock->lock_fd);
-               /* Do not free lock->lk -- atexit() still looks at them */
-               if (lock->lk)
-                       rollback_lock_file(lock->lk);
-       }
+       /* Do not free lock->lk -- atexit() still looks at them */
+       if (lock->lk)
+               rollback_lock_file(lock->lk);
        free(lock->ref_name);
-       free(lock->log_file);
+       free(lock->orig_ref_name);
        free(lock);
 }
 
-static int log_ref_write(struct ref_lock *lock,
-       const unsigned char *sha1, const char *msg)
+/*
+ * copy the reflog message msg to buf, which has been allocated sufficiently
+ * large, while cleaning up the whitespaces.  Especially, convert LF to space,
+ * because reflog file is one line per entry.
+ */
+static int copy_msg(char *buf, const char *msg)
+{
+       char *cp = buf;
+       char c;
+       int wasspace = 1;
+
+       *cp++ = '\t';
+       while ((c = *msg++)) {
+               if (wasspace && isspace(c))
+                       continue;
+               wasspace = isspace(c);
+               if (wasspace)
+                       c = ' ';
+               *cp++ = c;
+       }
+       while (buf < cp && isspace(cp[-1]))
+               cp--;
+       *cp++ = '\n';
+       return cp - buf;
+}
+
+int log_ref_setup(const char *ref_name, char *logfile, int bufsize)
 {
-       int logfd, written, oflags = O_APPEND | O_WRONLY;
-       unsigned maxlen, len;
-       char *logrec;
-       const char *committer;
+       int logfd, oflags = O_APPEND | O_WRONLY;
 
+       git_snpath(logfile, bufsize, "logs/%s", ref_name);
        if (log_all_ref_updates &&
-           !strncmp(lock->ref_name, "refs/heads/", 11)) {
-               if (safe_create_leading_directories(lock->log_file) < 0)
+           (!prefixcmp(ref_name, "refs/heads/") ||
+            !prefixcmp(ref_name, "refs/remotes/") ||
+            !prefixcmp(ref_name, "refs/notes/") ||
+            !strcmp(ref_name, "HEAD"))) {
+               if (safe_create_leading_directories(logfile) < 0)
                        return error("unable to create directory for %s",
-                               lock->log_file);
+                                    logfile);
                oflags |= O_CREAT;
        }
 
-       logfd = open(lock->log_file, oflags, 0666);
+       logfd = open(logfile, oflags, 0666);
        if (logfd < 0) {
                if (!(oflags & O_CREAT) && errno == ENOENT)
                        return 0;
 
                if ((oflags & O_CREAT) && errno == EISDIR) {
-                       if (remove_empty_directories(lock->log_file)) {
+                       if (remove_empty_directories(logfile)) {
                                return error("There are still logs under '%s'",
-                                            lock->log_file);
+                                            logfile);
                        }
-                       logfd = open(lock->log_file, oflags, 0666);
+                       logfd = open(logfile, oflags, 0666);
                }
 
                if (logfd < 0)
                        return error("Unable to append to %s: %s",
-                                    lock->log_file, strerror(errno));
-       }
-
-       committer = git_committer_info(1);
-       if (msg) {
-               maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
-               logrec = xmalloc(maxlen);
-               len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
-                       sha1_to_hex(lock->old_sha1),
-                       sha1_to_hex(sha1),
-                       committer,
-                       msg);
-       }
-       else {
-               maxlen = strlen(committer) + 2*40 + 4;
-               logrec = xmalloc(maxlen);
-               len = snprintf(logrec, maxlen, "%s %s %s\n",
-                       sha1_to_hex(lock->old_sha1),
-                       sha1_to_hex(sha1),
-                       committer);
-       }
-       written = len <= maxlen ? write(logfd, logrec, len) : -1;
-       free(logrec);
+                                    logfile, strerror(errno));
+       }
+
+       adjust_shared_perm(logfile);
        close(logfd);
-       if (written != len)
-               return error("Unable to append to %s", lock->log_file);
        return 0;
 }
 
+static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
+                        const unsigned char *new_sha1, const char *msg)
+{
+       int logfd, result, written, oflags = O_APPEND | O_WRONLY;
+       unsigned maxlen, len;
+       int msglen;
+       char log_file[PATH_MAX];
+       char *logrec;
+       const char *committer;
+
+       if (log_all_ref_updates < 0)
+               log_all_ref_updates = !is_bare_repository();
+
+       result = log_ref_setup(ref_name, log_file, sizeof(log_file));
+       if (result)
+               return result;
+
+       logfd = open(log_file, oflags);
+       if (logfd < 0)
+               return 0;
+       msglen = msg ? strlen(msg) : 0;
+       committer = git_committer_info(0);
+       maxlen = strlen(committer) + msglen + 100;
+       logrec = xmalloc(maxlen);
+       len = sprintf(logrec, "%s %s %s\n",
+                     sha1_to_hex(old_sha1),
+                     sha1_to_hex(new_sha1),
+                     committer);
+       if (msglen)
+               len += copy_msg(logrec + len - 1, msg) - 1;
+       written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
+       free(logrec);
+       if (close(logfd) != 0 || written != len)
+               return error("Unable to append to %s", log_file);
+       return 0;
+}
+
+static int is_branch(const char *refname)
+{
+       return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
+}
+
 int write_ref_sha1(struct ref_lock *lock,
        const unsigned char *sha1, const char *logmsg)
 {
        static char term = '\n';
+       struct object *o;
 
        if (!lock)
                return -1;
@@ -975,50 +1466,163 @@ int write_ref_sha1(struct ref_lock *lock,
                unlock_ref(lock);
                return 0;
        }
-       if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
-           write(lock->lock_fd, &term, 1) != 1
-               || close(lock->lock_fd) < 0) {
+       o = parse_object(sha1);
+       if (!o) {
+               error("Trying to write ref %s with nonexistent object %s",
+                       lock->ref_name, sha1_to_hex(sha1));
+               unlock_ref(lock);
+               return -1;
+       }
+       if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
+               error("Trying to write non-commit object %s to branch %s",
+                       sha1_to_hex(sha1), lock->ref_name);
+               unlock_ref(lock);
+               return -1;
+       }
+       if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
+           write_in_full(lock->lock_fd, &term, 1) != 1
+               || close_ref(lock) < 0) {
                error("Couldn't write %s", lock->lk->filename);
                unlock_ref(lock);
                return -1;
        }
        invalidate_cached_refs();
-       if (log_ref_write(lock, sha1, logmsg) < 0) {
+       if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
+           (strcmp(lock->ref_name, lock->orig_ref_name) &&
+            log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
                unlock_ref(lock);
                return -1;
        }
-       if (commit_lock_file(lock->lk)) {
+       if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
+               /*
+                * Special hack: If a branch is updated directly and HEAD
+                * points to it (may happen on the remote side of a push
+                * for example) then logically the HEAD reflog should be
+                * updated too.
+                * A generic solution implies reverse symref information,
+                * but finding all symrefs pointing to the given branch
+                * would be rather costly for this rare event (the direct
+                * update of a branch) to be worth it.  So let's cheat and
+                * check with HEAD only which should cover 99% of all usage
+                * scenarios (even 100% of the default ones).
+                */
+               unsigned char head_sha1[20];
+               int head_flag;
+               const char *head_ref;
+               head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
+               if (head_ref && (head_flag & REF_ISSYMREF) &&
+                   !strcmp(head_ref, lock->ref_name))
+                       log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
+       }
+       if (commit_ref(lock)) {
                error("Couldn't set %s", lock->ref_name);
                unlock_ref(lock);
                return -1;
        }
-       lock->lock_fd = -1;
        unlock_ref(lock);
        return 0;
 }
 
-int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *sha1)
+int create_symref(const char *ref_target, const char *refs_heads_master,
+                 const char *logmsg)
+{
+       const char *lockpath;
+       char ref[1000];
+       int fd, len, written;
+       char *git_HEAD = git_pathdup("%s", ref_target);
+       unsigned char old_sha1[20], new_sha1[20];
+
+       if (logmsg && read_ref(ref_target, old_sha1))
+               hashclr(old_sha1);
+
+       if (safe_create_leading_directories(git_HEAD) < 0)
+               return error("unable to create directory for %s", git_HEAD);
+
+#ifndef NO_SYMLINK_HEAD
+       if (prefer_symlink_refs) {
+               unlink(git_HEAD);
+               if (!symlink(refs_heads_master, git_HEAD))
+                       goto done;
+               fprintf(stderr, "no symlink - falling back to symbolic ref\n");
+       }
+#endif
+
+       len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
+       if (sizeof(ref) <= len) {
+               error("refname too long: %s", refs_heads_master);
+               goto error_free_return;
+       }
+       lockpath = mkpath("%s.lock", git_HEAD);
+       fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
+       if (fd < 0) {
+               error("Unable to open %s for writing", lockpath);
+               goto error_free_return;
+       }
+       written = write_in_full(fd, ref, len);
+       if (close(fd) != 0 || written != len) {
+               error("Unable to write to %s", lockpath);
+               goto error_unlink_return;
+       }
+       if (rename(lockpath, git_HEAD) < 0) {
+               error("Unable to create %s", git_HEAD);
+               goto error_unlink_return;
+       }
+       if (adjust_shared_perm(git_HEAD)) {
+               error("Unable to fix permissions on %s", lockpath);
+       error_unlink_return:
+               unlink_or_warn(lockpath);
+       error_free_return:
+               free(git_HEAD);
+               return -1;
+       }
+
+#ifndef NO_SYMLINK_HEAD
+       done:
+#endif
+       if (logmsg && !read_ref(refs_heads_master, new_sha1))
+               log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
+
+       free(git_HEAD);
+       return 0;
+}
+
+static char *ref_msg(const char *line, const char *endp)
+{
+       const char *ep;
+       line += 82;
+       ep = memchr(line, '\n', endp - line);
+       if (!ep)
+               ep = endp;
+       return xmemdupz(line, ep - line);
+}
+
+int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *sha1, char **msg, unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 {
        const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
        char *tz_c;
-       int logfd, tz;
+       int logfd, tz, reccnt = 0;
        struct stat st;
        unsigned long date;
        unsigned char logged_sha1[20];
+       void *log_mapped;
+       size_t mapsz;
 
        logfile = git_path("logs/%s", ref);
        logfd = open(logfile, O_RDONLY, 0);
        if (logfd < 0)
-               die("Unable to read log %s: %s", logfile, strerror(errno));
+               die_errno("Unable to read log '%s'", logfile);
        fstat(logfd, &st);
        if (!st.st_size)
                die("Log %s is empty.", logfile);
-       logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
+       mapsz = xsize_t(st.st_size);
+       log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
+       logdata = log_mapped;
        close(logfd);
 
        lastrec = NULL;
        rec = logend = logdata + st.st_size;
        while (logdata < rec) {
+               reccnt++;
                if (logdata < rec && *(rec-1) == '\n')
                        rec--;
                lastgt = NULL;
@@ -1031,16 +1635,23 @@ int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *
                        die("Log %s is corrupt.", logfile);
                date = strtoul(lastgt + 1, &tz_c, 10);
                if (date <= at_time || cnt == 0) {
+                       tz = strtoul(tz_c, NULL, 10);
+                       if (msg)
+                               *msg = ref_msg(rec, logend);
+                       if (cutoff_time)
+                               *cutoff_time = date;
+                       if (cutoff_tz)
+                               *cutoff_tz = tz;
+                       if (cutoff_cnt)
+                               *cutoff_cnt = reccnt - 1;
                        if (lastrec) {
                                if (get_sha1_hex(lastrec, logged_sha1))
                                        die("Log %s is corrupt.", logfile);
                                if (get_sha1_hex(rec + 41, sha1))
                                        die("Log %s is corrupt.", logfile);
                                if (hashcmp(logged_sha1, sha1)) {
-                                       tz = strtoul(tz_c, NULL, 10);
-                                       fprintf(stderr,
-                                               "warning: Log %s has gap after %s.\n",
-                                               logfile, show_rfc2822_date(date, tz));
+                                       warning("Log %s has gap after %s.",
+                                               logfile, show_date(date, tz, DATE_RFC2822));
                                }
                        }
                        else if (date == at_time) {
@@ -1051,13 +1662,11 @@ int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *
                                if (get_sha1_hex(rec + 41, logged_sha1))
                                        die("Log %s is corrupt.", logfile);
                                if (hashcmp(logged_sha1, sha1)) {
-                                       tz = strtoul(tz_c, NULL, 10);
-                                       fprintf(stderr,
-                                               "warning: Log %s unexpectedly ended on %s.\n",
-                                               logfile, show_rfc2822_date(date, tz));
+                                       warning("Log %s unexpectedly ended on %s.",
+                                               logfile, show_date(date, tz, DATE_RFC2822));
                                }
                        }
-                       munmap((void*)logdata, st.st_size);
+                       munmap(log_mapped, mapsz);
                        return 0;
                }
                lastrec = rec;
@@ -1074,8 +1683,287 @@ int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *
        tz = strtoul(tz_c, NULL, 10);
        if (get_sha1_hex(logdata, sha1))
                die("Log %s is corrupt.", logfile);
-       munmap((void*)logdata, st.st_size);
-       fprintf(stderr, "warning: Log %s only goes back to %s.\n",
-               logfile, show_rfc2822_date(date, tz));
+       if (is_null_sha1(sha1)) {
+               if (get_sha1_hex(logdata + 41, sha1))
+                       die("Log %s is corrupt.", logfile);
+       }
+       if (msg)
+               *msg = ref_msg(logdata, logend);
+       munmap(log_mapped, mapsz);
+
+       if (cutoff_time)
+               *cutoff_time = date;
+       if (cutoff_tz)
+               *cutoff_tz = tz;
+       if (cutoff_cnt)
+               *cutoff_cnt = reccnt;
+       return 1;
+}
+
+int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
+{
+       const char *logfile;
+       FILE *logfp;
+       struct strbuf sb = STRBUF_INIT;
+       int ret = 0;
+
+       logfile = git_path("logs/%s", ref);
+       logfp = fopen(logfile, "r");
+       if (!logfp)
+               return -1;
+
+       if (ofs) {
+               struct stat statbuf;
+               if (fstat(fileno(logfp), &statbuf) ||
+                   statbuf.st_size < ofs ||
+                   fseek(logfp, -ofs, SEEK_END) ||
+                   strbuf_getwholeline(&sb, logfp, '\n')) {
+                       fclose(logfp);
+                       strbuf_release(&sb);
+                       return -1;
+               }
+       }
+
+       while (!strbuf_getwholeline(&sb, logfp, '\n')) {
+               unsigned char osha1[20], nsha1[20];
+               char *email_end, *message;
+               unsigned long timestamp;
+               int tz;
+
+               /* old SP new SP name <email> SP time TAB msg LF */
+               if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
+                   get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
+                   get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
+                   !(email_end = strchr(sb.buf + 82, '>')) ||
+                   email_end[1] != ' ' ||
+                   !(timestamp = strtoul(email_end + 2, &message, 10)) ||
+                   !message || message[0] != ' ' ||
+                   (message[1] != '+' && message[1] != '-') ||
+                   !isdigit(message[2]) || !isdigit(message[3]) ||
+                   !isdigit(message[4]) || !isdigit(message[5]))
+                       continue; /* corrupt? */
+               email_end[1] = '\0';
+               tz = strtol(message + 1, NULL, 10);
+               if (message[6] != '\t')
+                       message += 6;
+               else
+                       message += 7;
+               ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
+                        cb_data);
+               if (ret)
+                       break;
+       }
+       fclose(logfp);
+       strbuf_release(&sb);
+       return ret;
+}
+
+int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
+{
+       return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
+}
+
+static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
+{
+       DIR *dir = opendir(git_path("logs/%s", base));
+       int retval = 0;
+
+       if (dir) {
+               struct dirent *de;
+               int baselen = strlen(base);
+               char *log = xmalloc(baselen + 257);
+
+               memcpy(log, base, baselen);
+               if (baselen && base[baselen-1] != '/')
+                       log[baselen++] = '/';
+
+               while ((de = readdir(dir)) != NULL) {
+                       struct stat st;
+                       int namelen;
+
+                       if (de->d_name[0] == '.')
+                               continue;
+                       namelen = strlen(de->d_name);
+                       if (namelen > 255)
+                               continue;
+                       if (has_extension(de->d_name, ".lock"))
+                               continue;
+                       memcpy(log + baselen, de->d_name, namelen+1);
+                       if (stat(git_path("logs/%s", log), &st) < 0)
+                               continue;
+                       if (S_ISDIR(st.st_mode)) {
+                               retval = do_for_each_reflog(log, fn, cb_data);
+                       } else {
+                               unsigned char sha1[20];
+                               if (!resolve_ref(log, sha1, 0, NULL))
+                                       retval = error("bad ref for %s", log);
+                               else
+                                       retval = fn(log, sha1, 0, cb_data);
+                       }
+                       if (retval)
+                               break;
+               }
+               free(log);
+               closedir(dir);
+       }
+       else if (*base)
+               return errno;
+       return retval;
+}
+
+int for_each_reflog(each_ref_fn fn, void *cb_data)
+{
+       return do_for_each_reflog("", fn, cb_data);
+}
+
+int update_ref(const char *action, const char *refname,
+               const unsigned char *sha1, const unsigned char *oldval,
+               int flags, enum action_on_err onerr)
+{
+       static struct ref_lock *lock;
+       lock = lock_any_ref_for_update(refname, oldval, flags);
+       if (!lock) {
+               const char *str = "Cannot lock the ref '%s'.";
+               switch (onerr) {
+               case MSG_ON_ERR: error(str, refname); break;
+               case DIE_ON_ERR: die(str, refname); break;
+               case QUIET_ON_ERR: break;
+               }
+               return 1;
+       }
+       if (write_ref_sha1(lock, sha1, action) < 0) {
+               const char *str = "Cannot update the ref '%s'.";
+               switch (onerr) {
+               case MSG_ON_ERR: error(str, refname); break;
+               case DIE_ON_ERR: die(str, refname); break;
+               case QUIET_ON_ERR: break;
+               }
+               return 1;
+       }
        return 0;
 }
+
+int ref_exists(char *refname)
+{
+       unsigned char sha1[20];
+       return !!resolve_ref(refname, sha1, 1, NULL);
+}
+
+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;
+}
+
+/*
+ * generate a format suitable for scanf from a ref_rev_parse_rules
+ * rule, that is replace the "%.*s" spec with a "%s" spec
+ */
+static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
+{
+       char *spec;
+
+       spec = strstr(rule, "%.*s");
+       if (!spec || strstr(spec + 4, "%.*s"))
+               die("invalid rule in ref_rev_parse_rules: %s", rule);
+
+       /* copy all until spec */
+       strncpy(scanf_fmt, rule, spec - rule);
+       scanf_fmt[spec - rule] = '\0';
+       /* copy new spec */
+       strcat(scanf_fmt, "%s");
+       /* copy remaining rule */
+       strcat(scanf_fmt, spec + 4);
+
+       return;
+}
+
+char *shorten_unambiguous_ref(const char *ref, int strict)
+{
+       int i;
+       static char **scanf_fmts;
+       static int nr_rules;
+       char *short_name;
+
+       /* pre generate scanf formats from ref_rev_parse_rules[] */
+       if (!nr_rules) {
+               size_t total_len = 0;
+
+               /* the rule list is NULL terminated, count them first */
+               for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
+                       /* no +1 because strlen("%s") < strlen("%.*s") */
+                       total_len += strlen(ref_rev_parse_rules[nr_rules]);
+
+               scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
+
+               total_len = 0;
+               for (i = 0; i < nr_rules; i++) {
+                       scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
+                                       + total_len;
+                       gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
+                       total_len += strlen(ref_rev_parse_rules[i]);
+               }
+       }
+
+       /* bail out if there are no rules */
+       if (!nr_rules)
+               return xstrdup(ref);
+
+       /* buffer for scanf result, at most ref must fit */
+       short_name = xstrdup(ref);
+
+       /* skip first rule, it will always match */
+       for (i = nr_rules - 1; i > 0 ; --i) {
+               int j;
+               int rules_to_fail = i;
+               int short_name_len;
+
+               if (1 != sscanf(ref, scanf_fmts[i], short_name))
+                       continue;
+
+               short_name_len = strlen(short_name);
+
+               /*
+                * in strict mode, all (except the matched one) rules
+                * must fail to resolve to a valid non-ambiguous ref
+                */
+               if (strict)
+                       rules_to_fail = nr_rules;
+
+               /*
+                * check if the short name resolves to a valid ref,
+                * but use only rules prior to the matched one
+                */
+               for (j = 0; j < rules_to_fail; j++) {
+                       const char *rule = ref_rev_parse_rules[j];
+                       unsigned char short_objectname[20];
+                       char refname[PATH_MAX];
+
+                       /* skip matched rule */
+                       if (i == j)
+                               continue;
+
+                       /*
+                        * the short name is ambiguous, if it resolves
+                        * (with this previous rule) to a valid ref
+                        * read_ref() returns 0 on success
+                        */
+                       mksnpath(refname, sizeof(refname),
+                                rule, short_name_len, short_name);
+                       if (!read_ref(refname, short_objectname))
+                               break;
+               }
+
+               /*
+                * short name is non-ambiguous if all previous rules
+                * haven't resolved to a valid ref
+                */
+               if (j == rules_to_fail)
+                       return short_name;
+       }
+
+       free(short_name);
+       return xstrdup(ref);
+}