Re: [PATCH] update-ref: fix streaming of status updates
From: Junio C Hamano <hidden>
Date: 2021-09-03 18:34:51
Patrick Steinhardt [off-list ref] writes:
When executing git-update-ref(1) with the `--stdin` flag, then the user can queue updates and, since e48cf33b61 (update-ref: implement interactive transaction handling, 2020-04-02), interactively drive the transaction's state via a set of transactional verbs. This interactivity is somewhat broken though: while the caller can use these verbs to drive the transaction's state, the status messages which confirm that a verb has been processed is not flushed. The caller may thus be left hanging waiting for the acknowledgement. Fix the bug by flushing stdout after writing the status update. Add a test which catches this bug.
Nobody hit by this for more than a year is interesting. Will queue. Thanks.
quoted hunk
Signed-off-by: Patrick Steinhardt <redacted> --- builtin/update-ref.c | 14 ++++++++++---- t/t1400-update-ref.sh | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 42 insertions(+), 4 deletions(-)diff --git a/builtin/update-ref.c b/builtin/update-ref.c index 6029a80544..a84e7b47a2 100644 --- a/builtin/update-ref.c +++ b/builtin/update-ref.c@@ -302,6 +302,12 @@ static void parse_cmd_verify(struct ref_transaction *transaction, strbuf_release(&err); } +static void report_ok(const char *command) +{ + fprintf(stdout, "%s: ok\n", command); + fflush(stdout); +} + static void parse_cmd_option(struct ref_transaction *transaction, const char *next, const char *end) {@@ -317,7 +323,7 @@ static void parse_cmd_start(struct ref_transaction *transaction, { if (*next != line_termination) die("start: extra input: %s", next); - puts("start: ok"); + report_ok("start"); } static void parse_cmd_prepare(struct ref_transaction *transaction,@@ -328,7 +334,7 @@ static void parse_cmd_prepare(struct ref_transaction *transaction, die("prepare: extra input: %s", next); if (ref_transaction_prepare(transaction, &error)) die("prepare: %s", error.buf); - puts("prepare: ok"); + report_ok("prepare"); } static void parse_cmd_abort(struct ref_transaction *transaction,@@ -339,7 +345,7 @@ static void parse_cmd_abort(struct ref_transaction *transaction, die("abort: extra input: %s", next); if (ref_transaction_abort(transaction, &error)) die("abort: %s", error.buf); - puts("abort: ok"); + report_ok("abort"); } static void parse_cmd_commit(struct ref_transaction *transaction,@@ -350,7 +356,7 @@ static void parse_cmd_commit(struct ref_transaction *transaction, die("commit: extra input: %s", next); if (ref_transaction_commit(transaction, &error)) die("commit: %s", error.buf); - puts("commit: ok"); + report_ok("commit"); ref_transaction_free(transaction); }diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh index 4506cd435b..1e754e258f 100755 --- a/t/t1400-update-ref.sh +++ b/t/t1400-update-ref.sh@@ -1598,6 +1598,38 @@ test_expect_success 'transaction cannot restart ongoing transaction' ' test_must_fail git show-ref --verify refs/heads/restart ' +test_expect_success PIPE 'transaction flushes status updates' ' + mkfifo in out && + (git update-ref --stdin <in >out &) && + + exec 9>in && + test_when_finished "exec 9>&-" && + + echo "start" >&9 && + echo "start: ok" >expected && + read line <out && + echo "$line" >actual && + test_cmp expected actual && + + echo "create refs/heads/flush $A" >&9 && + + echo prepare >&9 && + echo "prepare: ok" >expected && + read line <out && + echo "$line" >actual && + test_cmp expected actual && + + # This must now fail given that we have locked the ref. + test_must_fail git update-ref refs/heads/flush $B 2>stderr && + grep "fatal: update_ref failed for ref ${SQ}refs/heads/flush${SQ}: cannot lock ref" stderr && + + echo commit >&9 && + echo "commit: ok" >expected && + read line <out && + echo "$line" >actual && + test_cmp expected actual +' + test_expect_success 'directory not created deleting packed ref' ' git branch d1/d2/r1 HEAD && git pack-refs --all &&