mmap(win32): avoid copy-on-write when it is unnecessary
[gitweb.git] / refs / files-backend.c
index 3a27f275859acbe1afe516e4165f600b900f634a..81f68f846b69af65badfbe8c25d4a03601fb23c8 100644 (file)
@@ -199,17 +199,14 @@ static struct ref_entry *create_ref_entry(const char *refname,
                                          const unsigned char *sha1, int flag,
                                          int check_name)
 {
-       int len;
        struct ref_entry *ref;
 
        if (check_name &&
            check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
                die("Reference has invalid format: '%s'", refname);
-       len = strlen(refname) + 1;
-       ref = xmalloc(sizeof(struct ref_entry) + len);
+       FLEX_ALLOC_STR(ref, name, refname);
        hashcpy(ref->u.value.oid.hash, sha1);
        oidclr(&ref->u.value.peeled);
-       memcpy(ref->name, refname, len);
        ref->flag = flag;
        return ref;
 }
@@ -268,9 +265,7 @@ static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
                                          int incomplete)
 {
        struct ref_entry *direntry;
-       direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
-       memcpy(direntry->name, dirname, len);
-       direntry->name[len] = '\0';
+       FLEX_ALLOC_MEM(direntry, name, dirname, len);
        direntry->u.subdir.ref_cache = ref_cache;
        direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
        return direntry;
@@ -939,13 +934,10 @@ static void clear_loose_ref_cache(struct ref_cache *refs)
  */
 static struct ref_cache *create_ref_cache(const char *submodule)
 {
-       int len;
        struct ref_cache *refs;
        if (!submodule)
                submodule = "";
-       len = strlen(submodule) + 1;
-       refs = xcalloc(1, sizeof(struct ref_cache) + len);
-       memcpy(refs->name, submodule, len);
+       FLEX_ALLOC_STR(refs, name, submodule);
        refs->next = submodule_ref_caches;
        submodule_ref_caches = refs;
        return refs;
@@ -1858,12 +1850,17 @@ static int verify_lock(struct ref_lock *lock,
        if (read_ref_full(lock->ref_name,
                          mustexist ? RESOLVE_REF_READING : 0,
                          lock->old_oid.hash, NULL)) {
-               int save_errno = errno;
-               strbuf_addf(err, "can't verify ref %s", lock->ref_name);
-               errno = save_errno;
-               return -1;
+               if (old_sha1) {
+                       int save_errno = errno;
+                       strbuf_addf(err, "can't verify ref %s", lock->ref_name);
+                       errno = save_errno;
+                       return -1;
+               } else {
+                       hashclr(lock->old_oid.hash);
+                       return 0;
+               }
        }
-       if (hashcmp(lock->old_oid.hash, old_sha1)) {
+       if (old_sha1 && hashcmp(lock->old_oid.hash, old_sha1)) {
                strbuf_addf(err, "ref %s is at %s but expected %s",
                            lock->ref_name,
                            sha1_to_hex(lock->old_oid.hash),
@@ -1900,7 +1897,8 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
        const char *orig_refname = refname;
        struct ref_lock *lock;
        int last_errno = 0;
-       int type, lflags;
+       int type;
+       int lflags = 0;
        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
        int resolve_flags = 0;
        int attempts_remaining = 3;
@@ -1911,10 +1909,11 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 
        if (mustexist)
                resolve_flags |= RESOLVE_REF_READING;
-       if (flags & REF_DELETING) {
+       if (flags & REF_DELETING)
                resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
-               if (flags & REF_NODEREF)
-                       resolve_flags |= RESOLVE_REF_NO_RECURSE;
+       if (flags & REF_NODEREF) {
+               resolve_flags |= RESOLVE_REF_NO_RECURSE;
+               lflags |= LOCK_NO_DEREF;
        }
 
        refname = resolve_ref_unsafe(refname, resolve_flags,
@@ -1950,6 +1949,10 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 
                goto error_return;
        }
+
+       if (flags & REF_NODEREF)
+               refname = orig_refname;
+
        /*
         * If the ref did not exist and we are creating it, make sure
         * there is no existing packed ref whose name begins with our
@@ -1965,11 +1968,6 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 
        lock->lk = xcalloc(1, sizeof(struct lock_file));
 
-       lflags = 0;
-       if (flags & REF_NODEREF) {
-               refname = orig_refname;
-               lflags |= LOCK_NO_DEREF;
-       }
        lock->ref_name = xstrdup(refname);
        lock->orig_ref_name = xstrdup(orig_refname);
        strbuf_git_path(&ref_file, "%s", refname);
@@ -2003,7 +2001,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
                        goto error_return;
                }
        }
-       if (old_sha1 && verify_lock(lock, old_sha1, mustexist, err)) {
+       if (verify_lock(lock, old_sha1, mustexist, err)) {
                last_errno = errno;
                goto error_return;
        }
@@ -2191,10 +2189,9 @@ static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
 
        /* Schedule the loose reference for pruning if requested. */
        if ((cb->flags & PACK_REFS_PRUNE)) {
-               int namelen = strlen(entry->name) + 1;
-               struct ref_to_prune *n = xcalloc(1, sizeof(*n) + namelen);
+               struct ref_to_prune *n;
+               FLEX_ALLOC_STR(n, name, entry->name);
                hashcpy(n->sha1, entry->u.value.oid.hash);
-               memcpy(n->name, entry->name, namelen); /* includes NUL */
                n->next = cb->ref_to_prune;
                cb->ref_to_prune = n;
        }
@@ -2829,73 +2826,72 @@ static int commit_ref_update(struct ref_lock *lock,
        return 0;
 }
 
-int create_symref(const char *ref_target, const char *refs_heads_master,
-                 const char *logmsg)
+static int create_ref_symlink(struct ref_lock *lock, const char *target)
 {
-       char *lockpath = NULL;
-       char ref[1000];
-       int fd, len, written;
-       char *git_HEAD = git_pathdup("%s", ref_target);
-       unsigned char old_sha1[20], new_sha1[20];
-       struct strbuf err = STRBUF_INIT;
-
-       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);
-
+       int ret = -1;
 #ifndef NO_SYMLINK_HEAD
-       if (prefer_symlink_refs) {
-               unlink(git_HEAD);
-               if (!symlink(refs_heads_master, git_HEAD))
-                       goto done;
+       char *ref_path = get_locked_file_path(lock->lk);
+       unlink(ref_path);
+       ret = symlink(target, ref_path);
+       free(ref_path);
+
+       if (ret)
                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
-       }
 #endif
+       return ret;
+}
 
-       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 = mkpathdup("%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(lockpath);
-               free(git_HEAD);
-               return -1;
+static void update_symref_reflog(struct ref_lock *lock, const char *refname,
+                                const char *target, const char *logmsg)
+{
+       struct strbuf err = STRBUF_INIT;
+       unsigned char new_sha1[20];
+       if (logmsg && !read_ref(target, new_sha1) &&
+           log_ref_write(refname, lock->old_oid.hash, new_sha1, logmsg, 0, &err)) {
+               error("%s", err.buf);
+               strbuf_release(&err);
        }
-       free(lockpath);
+}
 
-#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, 0, &err)) {
+static int create_symref_locked(struct ref_lock *lock, const char *refname,
+                               const char *target, const char *logmsg)
+{
+       if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
+               update_symref_reflog(lock, refname, target, logmsg);
+               return 0;
+       }
+
+       if (!fdopen_lock_file(lock->lk, "w"))
+               return error("unable to fdopen %s: %s",
+                            lock->lk->tempfile.filename.buf, strerror(errno));
+
+       update_symref_reflog(lock, refname, target, logmsg);
+
+       /* no error check; commit_ref will check ferror */
+       fprintf(lock->lk->tempfile.fp, "ref: %s\n", target);
+       if (commit_ref(lock) < 0)
+               return error("unable to write symref for %s: %s", refname,
+                            strerror(errno));
+       return 0;
+}
+
+int create_symref(const char *refname, const char *target, const char *logmsg)
+{
+       struct strbuf err = STRBUF_INIT;
+       struct ref_lock *lock;
+       int ret;
+
+       lock = lock_ref_sha1_basic(refname, NULL, NULL, NULL, REF_NODEREF, NULL,
+                                  &err);
+       if (!lock) {
                error("%s", err.buf);
                strbuf_release(&err);
+               return -1;
        }
 
-       free(git_HEAD);
-       return 0;
+       ret = create_symref_locked(lock, refname, target, logmsg);
+       unlock_ref(lock);
+       return ret;
 }
 
 int reflog_exists(const char *refname)