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| author | Jim Meyering <meyering@redhat.com> | 2009-04-17 18:44:18 +0200 |
|---|---|---|
| committer | Jim Meyering <meyering@redhat.com> | 2009-04-22 21:52:11 +0200 |
| commit | c74fbaefebe91ca60e3a8582613a3714c740df65 (patch) | |
| tree | 45dcb7277ba56f6f879f1d64444643038791a49a /tests/Makefile.am | |
| parent | 2ad7da759490a5680844e1e4b6b4ac1d13b95d3b (diff) | |
| download | coreutils-c74fbaefebe91ca60e3a8582613a3714c740df65.tar.xz | |
cp: work around linux kernel bug: short-read != EOF on /proc
Remove the optimization that avoided up to 50% of cp's read syscalls.
Do not assume that a short read on a regular file indicates EOF.
When reading from a file in /proc on linux [at least 2.6.9 - 2.6.29]
into a 4k-byte buffer or larger, a short read does not
always indicate EOF. For example, "cp /proc/slabinfo /tmp"
copies only 4068 of the total 7493 bytes. This optimization
(25719a33154f0c62ea9881f0c79ae312dd4cec7a, Improve performance a bit
by optimizing away; 2005-11-24) appears to have been worth less than
a 2% speed-up (and usually much less), so the impact of removing it
is negligible.
* src/copy.c (copy_reg): Don't exit the loop early.
* tests/cp/proc-short-read: New test, lightly based on a suggestion
from Mike Frysinger, to exercise this fix.
* tests/Makefile.am (TESTS): Add cp/proc-short-read.
* NEWS (Improve robustness): Mention this change.
Diffstat (limited to 'tests/Makefile.am')
| -rw-r--r-- | tests/Makefile.am | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/tests/Makefile.am b/tests/Makefile.am index 8ce6a2118..c02f2de93 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -281,6 +281,7 @@ TESTS = \ cp/parent-perm-race \ cp/perm \ cp/preserve-2 \ + cp/proc-short-read \ cp/proc-zero-len \ cp/r-vs-symlink \ cp/same-file \ |