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 from a
background subshell, and reading and verifying its standard output
through another fifo 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 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 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 | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index e707fb861e..dcfaa9cc36 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -3148,63 +3148,74 @@ test_expect_success 'U: validate root delete result' '
# The commands in input_file should not produce any output on the file
# descriptor set with --cat-blob-fd (or stdout if unspecified).
#
# To make sure you're observing the side effects of checkpoint *before*
# fast-import terminates (and thus writes out its state), check that the
# fast-import process is still running using background_import_still_running
# *after* evaluating the test conditions.
background_import_then_checkpoint () {
options=$1
input_file=$2
mkfifo V.input
exec 8<>V.input
rm V.input
mkfifo V.output
exec 9<>V.output
rm V.output
- git fast-import $options <&8 >&9 &
- echo $! >V.pid
+ (
+ git fast-import $options <&8 >&9 &
+ echo $! >V.fi.pid
+ 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
+ ) &
+ echo $! >V.sh.pid
# We don't mind if fast-import has already died by the time the test
# ends.
- test_when_finished "
+ test_when_finished '
exec 8>&-; exec 9>&-;
- kill $(cat V.pid) && wait $(cat V.pid)
- true"
+ kill $(cat V.sh.pid) && wait $(cat V.sh.pid)
+ kill $(cat V.fi.pid) && wait $(cat V.sh.pid)
+ true'
# Start in the background to ensure we adhere strictly to (blocking)
# pipes writing sequence. We want to assume that the write below could
# block, e.g. if fast-import blocks writing its own output to &9
# because there is no reader on &9 yet.
(
cat "$input_file"
echo "checkpoint"
echo "progress checkpoint"
) >&8 &
error=1 ;# assume the worst
while read output <&9
do
if test "$output" = "progress checkpoint"
then
error=0
break
+ elif test "$output" = "UNEXPECTED"
+ then
+ break
fi
# otherwise ignore cruft
echo >&2 "cruft: $output"
done
if test $error -eq 1
then
false
fi
}
background_import_still_running () {
- if ! kill -0 "$(cat V.pid)"
+ if ! kill -0 "$(cat V.fi.pid)"
then
echo >&2 "background fast-import terminated too early"
false
fi
}
--
2.24.0.643.gac013444ca
