On 10/27/2010 06:11 PM, John Hein wrote: > And they all fail at ulimit -n 4 > with 'tar: a: Cannot open: Too many open files'
That's to be expected, as "tar" needs at least 2 file descriptors, one to read and one to write, plus the 3 standard file descriptors (stdin, stdout, stderr). Thanks, Eric, for passing along that suggestion. I still say the shells in question are buggy, because a shell should not fail to close a file descriptor unless close(fd) itself fails, but that's not a bug we have to fix here. I installed the following: >From 8099a072fef24c7039af1ec224187c94e34fdcec Mon Sep 17 00:00:00 2001 From: Paul Eggert <[email protected]> Date: Wed, 27 Oct 2010 20:25:18 -0700 Subject: [PATCH] tests: port to sh variants that squirrel away file descriptors OpenBSD /bin/sh, and some other sh variants, squirrel away file descriptors before closing them. For example, for "cat 3<&-" they first dup file descriptor 3 to a fd that is 10 or greater, then close 3 (because if "cat" had been a builtin command like ":" then they would have wanted to avoid the fork and restore the fd after ":" finished); and they treat ordinary (forking) commands the same as builtin commands. This approach fails after "ulimit -n 10". Work around this deficiency by closing the file descriptors before invoking ulimit. Problem reported by Christian Weisgerber in <http://lists.gnu.org/archive/html/bug-tar/2010-10/msg00041.html>; solution suggested by Jilles Tjoelker in <http://article.gmane.org/gmane.comp.shells.dash/415>. * tests/extrac11.at (scarce file descriptors): Close file descriptors before invoking ulimit -n. --- tests/extrac11.at | 26 ++++++++++++++++---------- 1 files changed, 16 insertions(+), 10 deletions(-) diff --git a/tests/extrac11.at b/tests/extrac11.at index 979b77c..0481c27 100644 --- a/tests/extrac11.at +++ b/tests/extrac11.at @@ -46,10 +46,14 @@ for dir in $dirs; do done done -# Check that "ulimit" itself works. -( (ulimit -n 100 && - tar -cf archive1.tar a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- && - tar -xf archive1.tar -C dest1 a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- +# Check that "ulimit" itself works. Close file descriptors before +# invoking ulimit, to work around a bug (or a "feature") in some shells, +# where they squirrel away dups of file descriptors into FD 10 and up +# before closing the originals. +( (exec 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- && + ulimit -n 100 && + tar -cf archive1.tar a && + tar -xf archive1.tar -C dest1 a ) && diff -r a dest1/a ) >/dev/null 2>&1 || @@ -57,18 +61,20 @@ done # Another test that "ulimit" itself works: # tar should fail when completely starved of file descriptors. -( (ulimit -n 4 && - tar -cf archive2.tar a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- && - tar -xf archive2.tar -C dest2 a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- +( (exec 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- && + ulimit -n 4 && + tar -cf archive2.tar a && + tar -xf archive2.tar -C dest2 a ) && diff -r a dest2/a ) >/dev/null 2>&1 && AT_SKIP_TEST # Tar should work when there are few, but enough, file descriptors. -( (ulimit -n 10 && - tar -cf archive3.tar a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- && - tar -xf archive3.tar -C dest3 a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- +( (exec 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- && + ulimit -n 10 && + tar -cf archive3.tar a && + tar -xf archive3.tar -C dest3 a ) && diff -r a dest3/a >/dev/null 2>&1 ) || { diff -r a dest3/a; exit 1; } -- 1.7.2
