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authorPádraig Brady <P@draigBrady.com>2008-12-01 01:08:02 +0000
committerPádraig Brady <P@draigBrady.com>2008-12-01 01:20:18 +0000
commite34894bf3f52f1600e5a334ddeec9c2a7e431853 (patch)
tree375ce7867cb3936ac5b821b78bbf011357683190 /tests
parentb14e5c40b9e7f6140a800a0b69eec693ea73fd09 (diff)
downloadcoreutils-e34894bf3f52f1600e5a334ddeec9c2a7e431853.tar.xz
tests: dd/reblock: Reduce chance of timing related failures
* tests/dd/reblock: Change the IPC mechanism to the dd process under test, from pipes to fifos. Also change the delay between data writes to 0.2s for both tests. This should increase the chance that the dd process will read the data chunks separately.
Diffstat (limited to 'tests')
-rwxr-xr-xtests/dd/reblock20
1 files changed, 15 insertions, 5 deletions
diff --git a/tests/dd/reblock b/tests/dd/reblock
index ef9e03613..7631acc19 100755
--- a/tests/dd/reblock
+++ b/tests/dd/reblock
@@ -24,12 +24,14 @@ fi
. $srcdir/lang-default
. $srcdir/test-lib.sh
+# 2 short reads -> 1 full write + 1 partial write
cat <<\EOF > exp-reblock || framework_failure
0+2 records in
1+1 records out
4 bytes (4 B) copied
EOF
+# 2 short reads -> 2 partial writes
cat <<\EOF > exp-no-reblock || framework_failure
0+2 records in
0+2 records out
@@ -38,16 +40,24 @@ EOF
fail=0
+# Use a fifo rather than a pipe in the tests below
+# so that the producer (printf subshell) will wait
+# until the consumer (dd) opens the fifo therefore
+# increasing the chance that dd will read the data
+# from each printf separately.
+mkfifo dd.fifo || framework_failure
+
# ensure that dd reblocks when bs= is not specified
-(echo x; sleep .1; echo y) | dd ibs=3 obs=3 > out 2> err || fail=1
+dd ibs=3 obs=3 if=dd.fifo > out 2> err&
+(printf 'ab'; sleep .2; printf 'cd') > dd.fifo
+wait #for dd to complete
sed 's/,.*//' err > k && mv k err
compare err exp-reblock || fail=1
# Demonstrate that bs=N supersedes even following ibs= and obs= settings.
-# Choosing a delay of 0.1 would result in an occasional lost race where
-# the consumer's first read would consume 3 bytes rather than the expected 2.
-# Not wanting to sleep a full second, I'll raise that to 0.3.
-(printf ab; sleep .3; printf cd) | dd bs=3 ibs=1 obs=1 > out 2> err || fail=1
+dd bs=3 ibs=1 obs=1 if=dd.fifo > out 2> err&
+(printf 'ab'; sleep .2; printf 'cd') > dd.fifo
+wait #for dd to complete
sed 's/,.*//' err > k && mv k err
compare err exp-no-reblock || fail=1