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[PATCH v2] pack-refs: fail on falsely sorted packed-refs

From
Max Kirillov <max@max630.net>
Date
Feb 8, 2019, 21:22 UTC
Message-ID
<20190208212221.31670-1-max@max630.net>
In-Reply-To
<CAPig+cTn2gURyQgWHZQMNf2cZ+zwFhbH1Q4iPmbwuvYjMrPZPg@mail.gmail.com>

If packed-refs is marked as sorted but not really sorted it causes very hard to comprehend misbehavior of reference resolving - a reference is reported as not found, though it is listed by commands which output the references list.

As the scope of the issue is not clear, make it visible by failing pack-refs command - the one which would not suffer performance penalty to verify the sortedness - when it encounters not really sorted existing data.

Signed-off-by: Max Kirillov <max@max630.net>
---
Fixed the notes
 refs/packed-backend.c               | 18 ++++++++++++++++++
 t/t3212-pack-refs-broken-sorting.sh | 26 ++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100755 t/t3212-pack-refs-broken-sorting.sh
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index c01c7f5901..c89a5eb899 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -1088,6 +1088,7 @@ static int write_with_updates(struct packed_ref_store *refs,
 	FILE *out;
 	struct strbuf sb = STRBUF_INIT;
 	char *packed_refs_path;
+	struct strbuf prev_ref = STRBUF_INIT;
 
 	if (!is_lock_file_locked(&refs->lock))
 		BUG("write_with_updates() called while unlocked");
@@ -1137,6 +1138,21 @@ static int write_with_updates(struct packed_ref_store *refs,
 		struct ref_update *update = NULL;
 		int cmp;
 
+		if (iter)
+		{
+			if (prev_ref.len &&  strcmp(prev_ref.buf, iter->refname) > 0)
+			{
+				strbuf_addf(err, "broken sorting in packed-refs: '%s' > '%s'",
+					    prev_ref.buf,
+					    iter->refname);
+				strbuf_release(&prev_ref);
+				goto error;
+			}
+
+			strbuf_init(&prev_ref, 0);
+			strbuf_addstr(&prev_ref, iter->refname);
+		}
+
 		if (i >= updates->nr) {
 			cmp = -1;
 		} else {
@@ -1240,6 +1256,8 @@ static int write_with_updates(struct packed_ref_store *refs,
 		}
 	}
 
+	strbuf_release(&prev_ref);
+
 	if (ok != ITER_DONE) {
 		strbuf_addstr(err, "unable to write packed-refs file: "
 			      "error iterating over old contents");
diff --git a/t/t3212-pack-refs-broken-sorting.sh b/t/t3212-pack-refs-broken-sorting.sh
new file mode 100755
index 0000000000..a44785c8fc
--- /dev/null
+++ b/t/t3212-pack-refs-broken-sorting.sh
@@ -0,0 +1,26 @@
+#!/bin/sh
+
+test_description='tests for the falsely sorted refs'
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git commit --allow-empty -m commit &&
+	for num in $(test_seq 10)
+	do
+		git branch b$(printf "%02d" $num) || return 1
+	done &&
+	git pack-refs --all &&
+	head_object=$(git rev-parse HEAD) &&
+	printf "$head_object refs/heads/b00\\n" >>.git/packed-refs &&
+	git branch b11
+'
+
+test_expect_success 'off-order branch not found' '
+	test_must_fail git show-ref --verify --quiet refs/heads/b00
+'
+
+test_expect_success 'subsequent pack-refs fails' '
+	test_must_fail git pack-refs --all
+'
+
+test_done
-- 
2.19.0.1202.g68e1e8f04e
Previous: Max KirillovNext: Eric Sunshine
Message 4 of 12 in “pack-refs: fail on falsely sorted packed-refs”
  1. pack-refs: fail on falsely sorted packed-refsMax Kirillov, Jan 30, 2019
  2. Eric SunshineJan 30, 2019
  3. Max KirillovJan 31, 2019
  4. pack-refs: fail on falsely sorted packed-refsMax Kirillov, Feb 8, 2019
  5. Eric SunshineFeb 8, 2019
  6. Max KirillovFeb 13, 2019
  7. Ævar Arnfjörð BjarmasonFeb 13, 2019
  8. SZEDER GáborFeb 13, 2019
  9. Max KirillovFeb 23, 2019
  10. Jeff KingFeb 14, 2019
  11. Max KirillovFeb 23, 2019
  12. Max KirillovFeb 13, 2019

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