ldd: make try_trace more robust and portable

It was noted in 2005 (BZ #832), 2006 (BZ #3266), and 2007 [1] that ldd
fails on shells other than Bash >= 3.0 because of the pipefail option
around try_trace (added on 2004-12-08).  EGLIBC was patched in 2008 [2]
(r6912) to make the pipefail check run only on shells that support it,
but RTLD output would still be lost on other shells with certain SELinux
policies.

This patch rewrites try_trace to work on any POSIX-conformant shell in
such a way as to also work with such SELinux policies.  It also obviates
one difference between glibc and EGLIBC.

URL: https://sourceware.org/ml/libc-alpha/2007-01/msg00041.html
URL: http://www.eglibc.org/archives/patches/msg00526.html

2013-09-11  P. J. McDermott  <pj@pehjota.net>

	[BZ #832]
	* elf/ldd.bash.in (try_trace): More robustly and portably work around
	SELinux terminal write permissions by using a command substitution
	instead of a pipeline and pipefail option.
This commit is contained in:
Patrick 'P. J.' McDermott 2013-09-11 23:13:36 -04:00 committed by Mike Frysinger
parent 0abe1dd536
commit 94bf958a94
3 changed files with 24 additions and 20 deletions

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@ -1,3 +1,9 @@
2013-10-14 P. J. McDermott <pj@pehjota.net>
[BZ #832]
* elf/ldd.bash.in (try_trace): New function. Delete previous code
testing pipefail option.
2013-10-12 Joseph Myers <joseph@codesourcery.com>
* soft-fp/double.h: Indent preprocessor directives inside #if.

13
NEWS
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@ -9,13 +9,12 @@ Version 2.19
* The following bugs are resolved with this release:
156, 431, 13982, 13985, 14155, 14547, 14699, 14910, 15048, 15362, 15400,
15427, 15522, 15531, 15532, 15608, 15609, 15610, 15632, 15640, 15680,
15681, 15723, 15734, 15735, 15736, 15748, 15749, 15754, 15760, 15764,
15797, 15844, 15847, 15849, 15855, 15856, 15857, 15859, 15867, 15886,
15887, 15890, 15892, 15893, 15895, 15897, 15905, 15909, 15919, 15921,
15887, 15890, 15892, 15893, 15895, 15897, 15905, 15909, 15919, 15921,
15923, 15939, 15963, 15966, 15988, 16032, 16034, 16036.
156, 431, 832, 13982, 13985, 14155, 14547, 14699, 14910, 15048, 15362,
15400, 15427, 15522, 15531, 15532, 15608, 15609, 15610, 15632, 15640,
15680, 15681, 15723, 15734, 15735, 15736, 15748, 15749, 15754, 15760,
15764, 15797, 15844, 15847, 15849, 15855, 15856, 15857, 15859, 15867,
15886, 15887, 15890, 15892, 15893, 15895, 15897, 15905, 15909, 15919,
15921, 15923, 15939, 15963, 15966, 15988, 16032, 16034, 16036.
* CVE-2012-4412 The strcoll implementation caches indices and rules for
large collation sequences to optimize multiple passes. This cache

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@ -106,19 +106,18 @@ if test "$unused" = yes; then
add_env="$add_env LD_DEBUG=\"$LD_DEBUG${LD_DEBUG:+,}unused\""
fi
# The following use of cat is needed to make ldd work in SELinux
# environments where the executed program might not have permissions
# to write to the console/tty. But only bash 3.x supports the pipefail
# option, and we don't bother to handle the case for older bash versions.
if set -o pipefail 2> /dev/null; then
try_trace() {
eval $add_env '"$@"' | cat
}
else
try_trace() {
eval $add_env '"$@"'
}
fi
# The following command substitution is needed to make ldd work in SELinux
# environments where the RTLD might not have permission to write to the
# terminal. The extra "x" character prevents the shell from trimming trailing
# newlines from command substitution results. This function is defined as a
# subshell compound list (using "(...)") to prevent parameter assignments from
# affecting the calling shell execution environment.
try_trace() (
output=$(eval $add_env '"$@"' 2>&1; rc=$?; printf 'x'; exit $rc)
rc=$?
printf '%s' "${output%x}"
return $rc
)
case $# in
0)