Merge branch 'rs/ref-transaction'

The API to update refs have been restructured to allow introducing
a true transactional updates later.  We would even allow storing
refs in backends other than the traditional filesystem-based one.

* rs/ref-transaction: (25 commits)
  ref_transaction_commit: bail out on failure to remove a ref
  lockfile: remove unable_to_lock_error
  refs.c: do not permit err == NULL
  remote rm/prune: print a message when writing packed-refs fails
  for-each-ref: skip and warn about broken ref names
  refs.c: allow listing and deleting badly named refs
  test: put tests for handling of bad ref names in one place
  packed-ref cache: forbid dot-components in refnames
  branch -d: simplify by using RESOLVE_REF_READING
  branch -d: avoid repeated symref resolution
  reflog test: test interaction with detached HEAD
  refs.c: change resolve_ref_unsafe reading argument to be a flags field
  refs.c: make write_ref_sha1 static
  fetch.c: change s_update_ref to use a ref transaction
  refs.c: ref_transaction_commit: distinguish name conflicts from other errors
  refs.c: pass a list of names to skip to is_refname_available
  refs.c: call lock_ref_sha1_basic directly from commit
  refs.c: refuse to lock badly named refs in lock_ref_sha1_basic
  rename_ref: don't ask read_ref_full where the ref came from
  refs.c: pass the ref log message to _create/delete/update instead of _commit
  ...

6 files changed, 322 insertions, 71 deletions

diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index 0218e96366..7b4707b776 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -110,6 +110,32 @@ test_expect_success "delete symref without dereference when the referred ref is
 cp -f .git/HEAD.orig .git/HEAD
 git update-ref -d $m
 
+test_expect_success 'update-ref -d is not confused by self-reference' '
+	git symbolic-ref refs/heads/self refs/heads/self &&
+	test_when_finished "rm -f .git/refs/heads/self" &&
+	test_path_is_file .git/refs/heads/self &&
+	test_must_fail git update-ref -d refs/heads/self &&
+	test_path_is_file .git/refs/heads/self
+'
+
+test_expect_success 'update-ref --no-deref -d can delete self-reference' '
+	git symbolic-ref refs/heads/self refs/heads/self &&
+	test_when_finished "rm -f .git/refs/heads/self" &&
+	test_path_is_file .git/refs/heads/self &&
+	git update-ref --no-deref -d refs/heads/self &&
+	test_path_is_missing .git/refs/heads/self
+'
+
+test_expect_success 'update-ref --no-deref -d can delete reference to bad ref' '
+	>.git/refs/heads/bad &&
+	test_when_finished "rm -f .git/refs/heads/bad" &&
+	git symbolic-ref refs/heads/ref-to-bad refs/heads/bad &&
+	test_when_finished "rm -f .git/refs/heads/ref-to-bad" &&
+	test_path_is_file .git/refs/heads/ref-to-bad &&
+	git update-ref --no-deref -d refs/heads/ref-to-bad &&
+	test_path_is_missing .git/refs/heads/ref-to-bad
+'
+
 test_expect_success '(not) create HEAD with old sha1' "
 	test_must_fail git update-ref HEAD $A $B
 "
@@ -374,12 +400,6 @@ test_expect_success 'stdin fails create with no ref' '
 	grep "fatal: create: missing <ref>" err
 '
 
-test_expect_success 'stdin fails create with bad ref name' '
-	echo "create ~a $m" >stdin &&
-	test_must_fail git update-ref --stdin <stdin 2>err &&
-	grep "fatal: invalid ref format: ~a" err
-'
-
 test_expect_success 'stdin fails create with no new value' '
 	echo "create $a" >stdin &&
 	test_must_fail git update-ref --stdin <stdin 2>err &&
@@ -398,12 +418,6 @@ test_expect_success 'stdin fails update with no ref' '
 	grep "fatal: update: missing <ref>" err
 '
 
-test_expect_success 'stdin fails update with bad ref name' '
-	echo "update ~a $m" >stdin &&
-	test_must_fail git update-ref --stdin <stdin 2>err &&
-	grep "fatal: invalid ref format: ~a" err
-'
-
 test_expect_success 'stdin fails update with no new value' '
 	echo "update $a" >stdin &&
 	test_must_fail git update-ref --stdin <stdin 2>err &&
@@ -422,12 +436,6 @@ test_expect_success 'stdin fails delete with no ref' '
 	grep "fatal: delete: missing <ref>" err
 '
 
-test_expect_success 'stdin fails delete with bad ref name' '
-	echo "delete ~a $m" >stdin &&
-	test_must_fail git update-ref --stdin <stdin 2>err &&
-	grep "fatal: invalid ref format: ~a" err
-'
-
 test_expect_success 'stdin fails delete with too many arguments' '
 	echo "delete $a $m $m" >stdin &&
 	test_must_fail git update-ref --stdin <stdin 2>err &&
@@ -700,12 +708,6 @@ test_expect_success 'stdin -z fails create with no ref' '
 	grep "fatal: create: missing <ref>" err
 '
 
-test_expect_success 'stdin -z fails create with bad ref name' '
-	printf $F "create ~a " "$m" >stdin &&
-	test_must_fail git update-ref -z --stdin <stdin 2>err &&
-	grep "fatal: invalid ref format: ~a " err
-'
-
 test_expect_success 'stdin -z fails create with no new value' '
 	printf $F "create $a" >stdin &&
 	test_must_fail git update-ref -z --stdin <stdin 2>err &&
@@ -730,12 +732,6 @@ test_expect_success 'stdin -z fails update with too few args' '
 	grep "fatal: update $a: unexpected end of input when reading <oldvalue>" err
 '
 
-test_expect_success 'stdin -z fails update with bad ref name' '
-	printf $F "update ~a" "$m" "" >stdin &&
-	test_must_fail git update-ref -z --stdin <stdin 2>err &&
-	grep "fatal: invalid ref format: ~a" err
-'
-
 test_expect_success 'stdin -z emits warning with empty new value' '
 	git update-ref $a $m &&
 	printf $F "update $a" "" "" >stdin &&
@@ -768,12 +764,6 @@ test_expect_success 'stdin -z fails delete with no ref' '
 	grep "fatal: delete: missing <ref>" err
 '
 
-test_expect_success 'stdin -z fails delete with bad ref name' '
-	printf $F "delete ~a" "$m" >stdin &&
-	test_must_fail git update-ref -z --stdin <stdin 2>err &&
-	grep "fatal: invalid ref format: ~a" err
-'
-
 test_expect_success 'stdin -z fails delete with no old value' '
 	printf $F "delete $a" >stdin &&
 	test_must_fail git update-ref -z --stdin <stdin 2>err &&
diff --git a/t/t1413-reflog-detach.sh b/t/t1413-reflog-detach.sh
new file mode 100755
index 0000000000..c730600d8a
--- /dev/null
+++ b/t/t1413-reflog-detach.sh
@@ -0,0 +1,70 @@
+#!/bin/sh
+
+test_description='Test reflog interaction with detached HEAD'
+. ./test-lib.sh
+
+reset_state () {
+	git checkout master &&
+	cp saved_reflog .git/logs/HEAD
+}
+
+test_expect_success setup '
+	test_tick &&
+	git commit --allow-empty -m initial &&
+	git branch side &&
+	test_tick &&
+	git commit --allow-empty -m second &&
+	cat .git/logs/HEAD >saved_reflog
+'
+
+test_expect_success baseline '
+	reset_state &&
+	git rev-parse master master^ >expect &&
+	git log -g --format=%H >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'switch to branch' '
+	reset_state &&
+	git rev-parse side master master^ >expect &&
+	git checkout side &&
+	git log -g --format=%H >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'detach to other' '
+	reset_state &&
+	git rev-parse master side master master^ >expect &&
+	git checkout side &&
+	git checkout master^0 &&
+	git log -g --format=%H >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'detach to self' '
+	reset_state &&
+	git rev-parse master master master^ >expect &&
+	git checkout master^0 &&
+	git log -g --format=%H >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'attach to self' '
+	reset_state &&
+	git rev-parse master master master master^ >expect &&
+	git checkout master^0 &&
+	git checkout master &&
+	git log -g --format=%H >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'attach to other' '
+	reset_state &&
+	git rev-parse side master master master^ >expect &&
+	git checkout master^0 &&
+	git checkout side &&
+	git log -g --format=%H >actual &&
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/t1430-bad-ref-name.sh b/t/t1430-bad-ref-name.sh
new file mode 100755
index 0000000000..468e85621a
--- /dev/null
+++ b/t/t1430-bad-ref-name.sh
@@ -0,0 +1,207 @@
+#!/bin/sh
+
+test_description='Test handling of ref names that check-ref-format rejects'
+. ./test-lib.sh
+
+test_expect_success setup '
+	test_commit one &&
+	test_commit two
+'
+
+test_expect_success 'fast-import: fail on invalid branch name ".badbranchname"' '
+	test_when_finished "rm -f .git/objects/pack_* .git/objects/index_*" &&
+	cat >input <<-INPUT_END &&
+		commit .badbranchname
+		committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+		data <<COMMIT
+		corrupt
+		COMMIT
+
+		from refs/heads/master
+
+	INPUT_END
+	test_must_fail git fast-import <input
+'
+
+test_expect_success 'fast-import: fail on invalid branch name "bad[branch]name"' '
+	test_when_finished "rm -f .git/objects/pack_* .git/objects/index_*" &&
+	cat >input <<-INPUT_END &&
+		commit bad[branch]name
+		committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+		data <<COMMIT
+		corrupt
+		COMMIT
+
+		from refs/heads/master
+
+	INPUT_END
+	test_must_fail git fast-import <input
+'
+
+test_expect_success 'git branch shows badly named ref' '
+	cp .git/refs/heads/master .git/refs/heads/broken...ref &&
+	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	git branch >output &&
+	grep -e "broken\.\.\.ref" output
+'
+
+test_expect_success 'branch -d can delete badly named ref' '
+	cp .git/refs/heads/master .git/refs/heads/broken...ref &&
+	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	git branch -d broken...ref &&
+	git branch >output &&
+	! grep -e "broken\.\.\.ref" output
+'
+
+test_expect_success 'branch -D can delete badly named ref' '
+	cp .git/refs/heads/master .git/refs/heads/broken...ref &&
+	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	git branch -D broken...ref &&
+	git branch >output &&
+	! grep -e "broken\.\.\.ref" output
+'
+
+test_expect_success 'branch -D cannot delete non-ref in .git dir' '
+	echo precious >.git/my-private-file &&
+	echo precious >expect &&
+	test_must_fail git branch -D ../../my-private-file &&
+	test_cmp expect .git/my-private-file
+'
+
+test_expect_success 'branch -D cannot delete absolute path' '
+	git branch -f extra &&
+	test_must_fail git branch -D "$(pwd)/.git/refs/heads/extra" &&
+	test_cmp_rev HEAD extra
+'
+
+test_expect_success 'git branch cannot create a badly named ref' '
+	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test_must_fail git branch broken...ref &&
+	git branch >output &&
+	! grep -e "broken\.\.\.ref" output
+'
+
+test_expect_success 'branch -m cannot rename to a bad ref name' '
+	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test_might_fail git branch -D goodref &&
+	git branch goodref &&
+	test_must_fail git branch -m goodref broken...ref &&
+	test_cmp_rev master goodref &&
+	git branch >output &&
+	! grep -e "broken\.\.\.ref" output
+'
+
+test_expect_failure 'branch -m can rename from a bad ref name' '
+	cp .git/refs/heads/master .git/refs/heads/broken...ref &&
+	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	git branch -m broken...ref renamed &&
+	test_cmp_rev master renamed &&
+	git branch >output &&
+	! grep -e "broken\.\.\.ref" output
+'
+
+test_expect_success 'push cannot create a badly named ref' '
+	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	test_must_fail git push "file://$(pwd)" HEAD:refs/heads/broken...ref &&
+	git branch >output &&
+	! grep -e "broken\.\.\.ref" output
+'
+
+test_expect_failure 'push --mirror can delete badly named ref' '
+	top=$(pwd) &&
+	git init src &&
+	git init dest &&
+
+	(
+		cd src &&
+		test_commit one
+	) &&
+	(
+		cd dest &&
+		test_commit two &&
+		git checkout --detach &&
+		cp .git/refs/heads/master .git/refs/heads/broken...ref
+	) &&
+	git -C src push --mirror "file://$top/dest" &&
+	git -C dest branch >output &&
+	! grep -e "broken\.\.\.ref" output
+'
+
+test_expect_success 'rev-parse skips symref pointing to broken name' '
+	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	git branch shadow one &&
+	cp .git/refs/heads/master .git/refs/heads/broken...ref &&
+	git symbolic-ref refs/tags/shadow refs/heads/broken...ref &&
+
+	git rev-parse --verify one >expect &&
+	git rev-parse --verify shadow >actual 2>err &&
+	test_cmp expect actual &&
+	test_i18ngrep "ignoring.*refs/tags/shadow" err
+'
+
+test_expect_success 'update-ref --no-deref -d can delete reference to broken name' '
+	git symbolic-ref refs/heads/badname refs/heads/broken...ref &&
+	test_when_finished "rm -f .git/refs/heads/badname" &&
+	test_path_is_file .git/refs/heads/badname &&
+	git update-ref --no-deref -d refs/heads/badname &&
+	test_path_is_missing .git/refs/heads/badname
+'
+
+test_expect_success 'update-ref -d can delete broken name' '
+	cp .git/refs/heads/master .git/refs/heads/broken...ref &&
+	test_when_finished "rm -f .git/refs/heads/broken...ref" &&
+	git update-ref -d refs/heads/broken...ref &&
+	git branch >output &&
+	! grep -e "broken\.\.\.ref" output
+'
+
+test_expect_success 'update-ref -d cannot delete non-ref in .git dir' '
+	echo precious >.git/my-private-file &&
+	echo precious >expect &&
+	test_must_fail git update-ref -d my-private-file &&
+	test_cmp expect .git/my-private-file
+'
+
+test_expect_success 'update-ref -d cannot delete absolute path' '
+	git branch -f extra &&
+	test_must_fail git update-ref -d "$(pwd)/.git/refs/heads/extra" &&
+	test_cmp_rev HEAD extra
+'
+
+test_expect_success 'update-ref --stdin fails create with bad ref name' '
+	echo "create ~a refs/heads/master" >stdin &&
+	test_must_fail git update-ref --stdin <stdin 2>err &&
+	grep "fatal: invalid ref format: ~a" err
+'
+
+test_expect_success 'update-ref --stdin fails update with bad ref name' '
+	echo "update ~a refs/heads/master" >stdin &&
+	test_must_fail git update-ref --stdin <stdin 2>err &&
+	grep "fatal: invalid ref format: ~a" err
+'
+
+test_expect_success 'update-ref --stdin fails delete with bad ref name' '
+	echo "delete ~a refs/heads/master" >stdin &&
+	test_must_fail git update-ref --stdin <stdin 2>err &&
+	grep "fatal: invalid ref format: ~a" err
+'
+
+test_expect_success 'update-ref --stdin -z fails create with bad ref name' '
+	printf "%s\0" "create ~a " refs/heads/master >stdin &&
+	test_must_fail git update-ref -z --stdin <stdin 2>err &&
+	grep "fatal: invalid ref format: ~a " err
+'
+
+test_expect_success 'update-ref --stdin -z fails update with bad ref name' '
+	printf "%s\0" "update ~a" refs/heads/master "" >stdin &&
+	test_must_fail git update-ref -z --stdin <stdin 2>err &&
+	grep "fatal: invalid ref format: ~a" err
+'
+
+test_expect_success 'update-ref --stdin -z fails delete with bad ref name' '
+	printf "%s\0" "delete ~a" refs/heads/master >stdin &&
+	test_must_fail git update-ref -z --stdin <stdin 2>err &&
+	grep "fatal: invalid ref format: ~a" err
+'
+
+test_done
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index ac31b711f2..432921b6b8 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -285,6 +285,15 @@ test_expect_success 'deleting a dangling symref' '
 	test_i18ncmp expect actual
 '
 
+test_expect_success 'deleting a self-referential symref' '
+	git symbolic-ref refs/heads/self-reference refs/heads/self-reference &&
+	test_path_is_file .git/refs/heads/self-reference &&
+	echo "Deleted branch self-reference (was refs/heads/self-reference)." >expect &&
+	git branch -d self-reference >actual &&
+	test_path_is_missing .git/refs/heads/self-reference &&
+	test_i18ncmp expect actual
+'
+
 test_expect_success 'renaming a symref is not allowed' '
 	git symbolic-ref refs/heads/master2 refs/heads/master &&
 	test_must_fail git branch -m master2 master3 &&
diff --git a/t/t7001-mv.sh b/t/t7001-mv.sh
index 54d78079e8..69f11bd40d 100755
--- a/t/t7001-mv.sh
+++ b/t/t7001-mv.sh
@@ -350,10 +350,11 @@ test_expect_success 'git mv moves a submodule with a .git directory and .gitmodu
 '
 
 test_expect_success 'git mv moves a submodule with gitfile' '
-	rm -rf mod/sub &&
+	rm -rf mod &&
 	git reset --hard &&
 	git submodule update &&
 	entry="$(git ls-files --stage sub | cut -f 1)" &&
+	mkdir mod &&
 	(
 		cd mod &&
 		git mv ../sub/ .
@@ -372,11 +373,12 @@ test_expect_success 'git mv moves a submodule with gitfile' '
 '
 
 test_expect_success 'mv does not complain when no .gitmodules file is found' '
-	rm -rf mod/sub &&
+	rm -rf mod &&
 	git reset --hard &&
 	git submodule update &&
 	git rm .gitmodules &&
 	entry="$(git ls-files --stage sub | cut -f 1)" &&
+	mkdir mod &&
 	git mv sub mod/sub 2>actual.err &&
 	! test -s actual.err &&
 	! test -e sub &&
@@ -390,11 +392,12 @@ test_expect_success 'mv does not complain when no .gitmodules file is found' '
 '
 
 test_expect_success 'mv will error out on a modified .gitmodules file unless staged' '
-	rm -rf mod/sub &&
+	rm -rf mod &&
 	git reset --hard &&
 	git submodule update &&
 	git config -f .gitmodules foo.bar true &&
 	entry="$(git ls-files --stage sub | cut -f 1)" &&
+	mkdir mod &&
 	test_must_fail git mv sub mod/sub 2>actual.err &&
 	test -s actual.err &&
 	test -e sub &&
@@ -413,13 +416,14 @@ test_expect_success 'mv will error out on a modified .gitmodules file unless sta
 '
 
 test_expect_success 'mv issues a warning when section is not found in .gitmodules' '
-	rm -rf mod/sub &&
+	rm -rf mod &&
 	git reset --hard &&
 	git submodule update &&
 	git config -f .gitmodules --remove-section submodule.sub &&
 	git add .gitmodules &&
 	entry="$(git ls-files --stage sub | cut -f 1)" &&
 	echo "warning: Could not find section in .gitmodules where path=sub" >expect.err &&
+	mkdir mod &&
 	git mv sub mod/sub 2>actual.err &&
 	test_i18ncmp expect.err actual.err &&
 	! test -e sub &&
@@ -433,9 +437,10 @@ test_expect_success 'mv issues a warning when section is not found in .gitmodule
 '
 
 test_expect_success 'mv --dry-run does not touch the submodule or .gitmodules' '
-	rm -rf mod/sub &&
+	rm -rf mod &&
 	git reset --hard &&
 	git submodule update &&
+	mkdir mod &&
 	git mv -n sub mod/sub 2>actual.err &&
 	test -f sub/.git &&
 	git diff-index --exit-code HEAD &&
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index 8df0445a84..37c2d633f0 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -347,36 +347,6 @@ test_expect_success 'B: fail on invalid blob sha1' '
 rm -f .git/objects/pack_* .git/objects/index_*
 
 cat >input <<INPUT_END
-commit .badbranchname
-committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
-data <<COMMIT
-corrupt
-COMMIT
-
-from refs/heads/master
-
-INPUT_END
-test_expect_success 'B: fail on invalid branch name ".badbranchname"' '
-    test_must_fail git fast-import <input
-'
-rm -f .git/objects/pack_* .git/objects/index_*
-
-cat >input <<INPUT_END
-commit bad[branch]name
-committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
-data <<COMMIT
-corrupt
-COMMIT
-
-from refs/heads/master
-
-INPUT_END
-test_expect_success 'B: fail on invalid branch name "bad[branch]name"' '
-    test_must_fail git fast-import <input
-'
-rm -f .git/objects/pack_* .git/objects/index_*
-
-cat >input <<INPUT_END
 commit TEMP_TAG
 committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
 data <<COMMIT