| Message ID | 1e9e62a2c5f74db91aaded83783076c28b757836.1630659922.git.ps@pks.im (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 4ae19a5f3487527927045d7305ececf0cc215436 |
| Headers | show |
| Series | update-ref: fix streaming of status updates | expand |
Patrick Steinhardt <ps@pks.im> 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. > > Signed-off-by: Patrick Steinhardt <ps@pks.im> > --- > 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 "$line" >actual && > + test_cmp expected actual > +' > + > test_expect_success 'directory not created deleting packed ref' ' > git branch d1/d2/r1 HEAD && > git pack-refs --all &&
> diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh > index 4506cd435b..1e754e258f 100755 > --- a/t/t1400-update-ref.sh > +++ b/t/t1400-update-ref.sh > @@ -1598,6 +1598,38 @@ test_expect_success 'transaction cannot restart ongoing transaction' ' > test_must_fail git show-ref --verify refs/heads/restart > ' > > +test_expect_success PIPE 'transaction flushes status updates' ' > + mkfifo in out && > + (git update-ref --stdin <in >out &) && > + > + exec 9>in && > + test_when_finished "exec 9>&-" && > + > + echo "start" >&9 && > + echo "start: ok" >expected && > + read line <out && > + echo "$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 && I think this test may be racy. I saw a strange failure from it in CI: https://github.com/peff/git/runs/3605506649?check_suite_focus=true#step:5:6734 I can't reproduce the problem locally with "--stress", but the failure there is on macOS (and likewise, a nearby run failed with a timeout just for macOS, which could be caused by a racy deadlock). I'm guessing the problem may be the continued opening and closing of "out" by the read calls from the shell. The update-ref process may get SIGPIPE as a result, depending on the write timing. The solution is to use open a descriptor for "out" like we do for "in", and then read from that. See 4783e7ea83 (t0008: avoid SIGPIPE race condition on fifo, 2013-07-12) for some prior art. -Peff
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 &&
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. Signed-off-by: Patrick Steinhardt <ps@pks.im> --- builtin/update-ref.c | 14 ++++++++++---- t/t1400-update-ref.sh | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 42 insertions(+), 4 deletions(-)