[kvm-unit-tests PATCH v3 1/8] arch-run: Fix TRAP handler recursion to remove temporary files properly

[Nicholas Piggin]

Migration files were not being removed when the QEMU process is
interrupted (e.g., with ^C). This is becaus the SIGINT propagates to the
bash TRAP handler, which recursively TRAPs due to the 'kill 0' in the
handler. This eventually crashes bash.

This can be observed by interrupting a long-running test program that is
run with MIGRATION=yes, /tmp/mig-helper-* files remain afterwards.

Removing TRAP recursion solves this problem and allows the EXIT handler
to run and clean up the files.

This also moves the trap handler before temp file creation, and expands
the name variables at trap-time rather than install-time, which closes
the small race between creation trap handler install.

Reviewed-by: Thomas Huth <thuth at redhat.com>
Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 scripts/arch-run.bash | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/scripts/arch-run.bash b/scripts/arch-run.bash
index d0864360..11d47a85 100644
--- a/scripts/arch-run.bash
+++ b/scripts/arch-run.bash
@@ -129,6 +129,9 @@ run_migration ()
 		return 77
 	fi
 
+	trap 'trap - TERM ; kill 0 ; exit 2' INT TERM
+	trap 'rm -f ${migout1} ${migsock} ${qmp1} ${qmp2} ${fifo}' RETURN EXIT
+
 	migsock=$(mktemp -u -t mig-helper-socket.XXXXXXXXXX)
 	migout1=$(mktemp -t mig-helper-stdout1.XXXXXXXXXX)
 	qmp1=$(mktemp -u -t mig-helper-qmp1.XXXXXXXXXX)
@@ -137,9 +140,6 @@ run_migration ()
 	qmpout1=/dev/null
 	qmpout2=/dev/null
 
-	trap 'kill 0; exit 2' INT TERM
-	trap 'rm -f ${migout1} ${migsock} ${qmp1} ${qmp2} ${fifo}' RETURN EXIT
-
 	eval "$@" -chardev socket,id=mon1,path=${qmp1},server=on,wait=off \
 		-mon chardev=mon1,mode=control | tee ${migout1} &
 	live_pid=`jobs -l %+ | grep "eval" | awk '{print$2}'`
@@ -209,11 +209,11 @@ run_panic ()
 		return 77
 	fi
 
-	qmp=$(mktemp -u -t panic-qmp.XXXXXXXXXX)
-
-	trap 'kill 0; exit 2' INT TERM
+	trap 'trap - TERM ; kill 0 ; exit 2' INT TERM
 	trap 'rm -f ${qmp}' RETURN EXIT
 
+	qmp=$(mktemp -u -t panic-qmp.XXXXXXXXXX)
+
 	# start VM stopped so we don't miss any events
 	eval "$@" -chardev socket,id=mon1,path=${qmp},server=on,wait=off \
 		-mon chardev=mon1,mode=control -S &
-- 
2.42.0