The five tests checking 'git fast-import's checkpoint handling in
't9300-fast-import.sh', all with the prefix "V:" in their test
description, can hang indefinitely if 'git fast-import' unexpectedly
dies early in any of these tests.
These five tests run 'git fast-import' in the background, while
feeding instructions to its standard input through a fifo (fd 8) from
a background subshell, and reading and verifying its standard output
through another fifo (fd 9) in the test script's main shell process.
This "reading and verifying" is basically a 'while read ...' shell
loop iterating until 'git fast-import' outputs the expected line,
ignoring any other output. This doesn't work very well when 'git
fast-import' dies before printing that particular line, because the
'read' builtin doesn't get EOF after the death of 'git fast-import',
as their input and output are not connected directly but through a
fifo. Consequently, that 'read' hangs waiting for the next line from
the already dead 'git fast-import', leaving the test script and in
turn the whole test suite hanging.
Avoid this hang by checking whether the background 'git fast-import'
process exited unexpectedly early, and interrupt the 'while read' loop
if it did. We have to jump through some hoops to achive that, though:
- Start the background 'git fast-import' in another background
subshell, which then:
- prints the PID of that 'git fast-import' process to the fifo,
to be read by the main shell process, so it will know which
process to kill when the test is finished.
- waits until that 'git fast-import' process exits. If it does
exit, then report its exit code, and write a message to the
fifo used for 'git fast-import's standard output, thus
un-block the 'read' builtin in the main shell process.
- Modify that 'while read' loop to break the loop upon seeing that
message, and fail the test in the usual way.
- Once the test is finished kill that background subshell as well,
and do so before killing the background 'git fast-import'.
Otherwise the background 'git fast-import' and subshell processes
would die racily, and if 'git fast-import' were to die sooner,
then we might get some undesired and potentially confusing
messages in the test's output.
Signed-off-by: SZEDER Gábor <szeder.dev@xxxxxxxxx>
---
t/t9300-fast-import.sh | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index 6820ebbb63..8f6f80f021 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -3164,12 +3164,21 @@ background_import_then_checkpoint () {
exec 9<>V.output
rm V.output
- git fast-import $options <&8 >&9 &
- fi_pid=$!
+ (
+ git fast-import $options <&8 >&9 &
+ echo $! >&9
+ wait $!
+ echo >&2 "background fast-import terminated too early with exit code $?"
+ # Un-block the read loop in the main shell process.
+ echo >&9 UNEXPECTED
+ ) &
+ sh_pid=$!
+ read fi_pid <&9
# We don't mind if fast-import has already died by the time the test
# ends.
test_when_finished "
exec 8>&-; exec 9>&-;
+ kill $sh_pid && wait $sh_pid
kill $fi_pid && wait $fi_pid
true"
@@ -3190,6 +3199,9 @@ background_import_then_checkpoint () {
then
error=0
break
+ elif test "$output" = "UNEXPECTED"
+ then
+ break
fi
# otherwise ignore cruft
echo >&2 "cruft: $output"
--
2.24.0.801.g241c134b8d
