git-update-ref: add --no-deref option for overwriting/detaching ref

git-checkout is also adapted to make use of this new option
instead of the handcrafted command sequence.

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/Documentation/git-update-ref.txt b/Documentation/git-update-ref.txt
index 9424fea..f222616 100644 (file)
--- a/Documentation/git-update-ref.txt
+++ b/Documentation/git-update-ref.txt
@@ -7,7 +7,7 @@ git-update-ref - Update the object name stored in a ref safely
 
 SYNOPSIS
 --------
-'git-update-ref' [-m <reason>] (-d <ref> <oldvalue> | <ref> <newvalue> [<oldvalue>])
+'git-update-ref' [-m <reason>] (-d <ref> <oldvalue> | [--no-deref] <ref> <newvalue> [<oldvalue>])
 
 DESCRIPTION
 -----------
@@ -36,6 +36,9 @@ them and update them as a regular file (i.e. it will allow the
 filesystem to follow them, but will overwrite such a symlink to
 somewhere else with a regular filename).
 
+If --no-deref is given, <ref> itself is overwritten, rather than
+the result of following the symbolic pointers.
+
 In general, using
 
        git-update-ref HEAD "$head"

diff --git a/builtin-branch.c b/builtin-branch.c
index 7408285..6bd5843 100644 (file)
--- a/builtin-branch.c
+++ b/builtin-branch.c
@@ -462,7 +462,7 @@ static void create_branch(const char *name, const char *start_name,
                die("Not a valid branch point: '%s'.", start_name);
        hashcpy(sha1, commit->object.sha1);
 
-       lock = lock_any_ref_for_update(ref, NULL);
+       lock = lock_any_ref_for_update(ref, NULL, 0);
        if (!lock)
                die("Failed to lock ref for update: %s.", strerror(errno));
 

diff --git a/builtin-fetch--tool.c b/builtin-fetch--tool.c
index 2065466..b14e78a 100644 (file)
--- a/builtin-fetch--tool.c
+++ b/builtin-fetch--tool.c
@@ -42,7 +42,7 @@ static int update_ref(const char *action,
        if (!rla)
                rla = "(reflog update)";
        snprintf(msg, sizeof(msg), "%s: %s", rla, action);
-       lock = lock_any_ref_for_update(refname, oldval);
+       lock = lock_any_ref_for_update(refname, oldval, 0);
        if (!lock)
                return 1;
        if (write_ref_sha1(lock, sha1, msg) < 0)

diff --git a/builtin-reflog.c b/builtin-reflog.c
index 4c39f1d..ce093ca 100644 (file)
--- a/builtin-reflog.c
+++ b/builtin-reflog.c
@@ -249,7 +249,7 @@ static int expire_reflog(const char *ref, const unsigned char *sha1, int unused,
        /* we take the lock for the ref itself to prevent it from
         * getting updated.
         */
-       lock = lock_any_ref_for_update(ref, sha1);
+       lock = lock_any_ref_for_update(ref, sha1, 0);
        if (!lock)
                return error("cannot lock ref '%s'", ref);
        log_file = xstrdup(git_path("logs/%s", ref));

diff --git a/builtin-update-ref.c b/builtin-update-ref.c
index 5ee960b..feac2ed 100644 (file)
--- a/builtin-update-ref.c
+++ b/builtin-update-ref.c
@@ -3,16 +3,17 @@
 #include "builtin.h"
 
 static const char git_update_ref_usage[] =
-"git-update-ref [-m <reason>] (-d <refname> <value> | <refname> <value> [<oldval>])";
+"git-update-ref [-m <reason>] (-d <refname> <value> | [--no-deref] <refname> <value> [<oldval>])";
 
 int cmd_update_ref(int argc, const char **argv, const char *prefix)
 {
        const char *refname=NULL, *value=NULL, *oldval=NULL, *msg=NULL;
        struct ref_lock *lock;
        unsigned char sha1[20], oldsha1[20];
-       int i, delete;
+       int i, delete, ref_flags;
 
        delete = 0;
+       ref_flags = 0;
        git_config(git_default_config);
 
        for (i = 1; i < argc; i++) {
@@ -30,6 +31,10 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
                        delete = 1;
                        continue;
                }
+               if (!strcmp("--no-deref", argv[i])) {
+                       ref_flags |= REF_NODEREF;
+                       continue;
+               }
                if (!refname) {
                        refname = argv[i];
                        continue;
@@ -59,7 +64,7 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
        if (oldval && *oldval && get_sha1(oldval, oldsha1))
                die("%s: not a valid old SHA1", oldval);
 
-       lock = lock_any_ref_for_update(refname, oldval ? oldsha1 : NULL);
+       lock = lock_any_ref_for_update(refname, oldval ? oldsha1 : NULL, ref_flags);
        if (!lock)
                die("%s: cannot lock the ref", refname);
        if (write_ref_sha1(lock, sha1, msg) < 0)

diff --git a/fast-import.c b/fast-import.c
index 3a2d5ed..ffa00fd 100644 (file)
--- a/fast-import.c
+++ b/fast-import.c
@@ -1271,7 +1271,7 @@ static int update_branch(struct branch *b)
 
        if (read_ref(b->name, old_sha1))
                hashclr(old_sha1);
-       lock = lock_any_ref_for_update(b->name, old_sha1);
+       lock = lock_any_ref_for_update(b->name, old_sha1, 0);
        if (!lock)
                return error("Unable to lock %s", b->name);
        if (!force_update && !is_null_sha1(old_sha1)) {

diff --git a/git-checkout.sh b/git-checkout.sh
index ed7c2c5..6b6facf 100755 (executable)
--- a/git-checkout.sh
+++ b/git-checkout.sh
@@ -270,15 +270,7 @@ if [ "$?" -eq 0 ]; then
                fi
        elif test -n "$detached"
        then
-               # NEEDSWORK: we would want a command to detach the HEAD
-               # atomically, instead of this handcrafted command sequence.
-               # Perhaps:
-               #       git update-ref --detach HEAD $new
-               # or something like that...
-               #
-               git-rev-parse HEAD >"$GIT_DIR/HEAD.new" &&
-               mv "$GIT_DIR/HEAD.new" "$GIT_DIR/HEAD" &&
-               git-update-ref -m "checkout: moving to $arg" HEAD "$detached" ||
+               git-update-ref --no-deref -m "checkout: moving to $arg" HEAD "$detached" ||
                        die "Cannot detach HEAD"
                if test -n "$detach_warn"
                then

diff --git a/receive-pack.c b/receive-pack.c
index 26aa26b..d3c422b 100644 (file)
--- a/receive-pack.c
+++ b/receive-pack.c
@@ -209,7 +209,7 @@ static const char *update(struct command *cmd)
                return NULL; /* good */
        }
        else {
-               lock = lock_any_ref_for_update(name, old_sha1);
+               lock = lock_any_ref_for_update(name, old_sha1, 0);
                if (!lock) {
                        error("failed to lock %s", name);
                        return "failed to lock";

diff --git a/refs.c b/refs.c
index 89876bf..2ae3235 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -736,19 +736,20 @@ 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;
        int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 
        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;
@@ -761,8 +762,10 @@ 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",
@@ -780,10 +783,15 @@ static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char
 
        lock->lk = xcalloc(1, sizeof(struct lock_file));
 
+       if (flags & REF_NODEREF)
+               ref = orig_ref;
        lock->ref_name = xstrdup(ref);
        lock->orig_ref_name = xstrdup(orig_ref);
        ref_file = git_path("%s", ref);
-       lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
+       if (lstat(ref_file, &st) && errno == ENOENT)
+               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;
@@ -806,14 +814,14 @@ 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)
 {
        if (check_ref_format(ref) == -1)
                return NULL;
-       return lock_ref_sha1_basic(ref, old_sha1, NULL);
+       return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
 }
 
 static struct lock_file packlock;
@@ -858,7 +866,7 @@ int delete_ref(const char *refname, const unsigned char *sha1)
        struct ref_lock *lock;
        int err, i, 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)) {
@@ -909,7 +917,7 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
        if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
                return 1;
 
-       lock = lock_ref_sha1_basic(renamed_ref, NULL, NULL);
+       lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
        if (!lock)
                return error("unable to lock %s", renamed_ref);
        lock->force_write = 1;
@@ -963,7 +971,7 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
        }
        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;
@@ -979,7 +987,7 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
        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;

diff --git a/refs.h b/refs.h
index f61f6d9..f234eb7 100644 (file)
--- a/refs.h
+++ b/refs.h
@@ -33,7 +33,8 @@ extern int get_ref_sha1(const char *ref, unsigned char *sha1);
 extern struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1);
 
 /** Locks any ref (for 'HEAD' type refs). */
-extern struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1);
+#define REF_NODEREF    0x01
+extern struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags);
 
 /** Release any lock taken but not written. **/
 extern void unlock_ref(struct ref_lock *lock);