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# Copyright 1999-2014 Gentoo Foundation |
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# Distributed under the terms of the GNU General Public License v2 |
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# $Header: /var/cvsroot/gentoo-x86/eclass/pax-utils.eclass,v 1.23 2014/08/30 14:06:04 blueness Exp $ |
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# @ECLASS: pax-utils.eclass |
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# @MAINTAINER: |
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# The Gentoo Linux Hardened Team <hardened@gentoo.org> |
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# @AUTHOR: |
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# Original Author: Kevin F. Quinn <kevquinn@gentoo.org> |
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# Modifications for bugs #365825, #431092, #520198, @ ECLASS markup: Anthony G. Basile <blueness@gentoo.org> |
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# @BLURB: functions to provide pax markings |
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# @DESCRIPTION: |
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# |
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# This eclass provides support for manipulating PaX markings on ELF binaries, |
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# whether the system is using legacy PT_PAX markings or the newer XATTR_PAX. |
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# The eclass wraps the use of paxctl-ng, paxctl, set/getattr and scanelf utilities, |
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# deciding which to use depending on what's installed on the build host, and |
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# whether we're working with PT_PAX, XATTR_PAX or both. |
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# |
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# To control what markings are made, set PAX_MARKINGS in /etc/portage/make.conf |
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# to contain either "PT", "XT" or "none". The default is to attempt both |
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# PT_PAX and XATTR_PAX. |
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|
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if [[ -z ${_PAX_UTILS_ECLASS} ]]; then |
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_PAX_UTILS_ECLASS=1 |
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|
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# @ECLASS-VARIABLE: PAX_MARKINGS |
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# @DESCRIPTION: |
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# Control which markings are made: |
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# PT = PT_PAX markings, XT = XATTR_PAX markings |
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# Default to PT markings. |
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PAX_MARKINGS=${PAX_MARKINGS:="PT"} |
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|
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# @FUNCTION: pax-mark |
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# @USAGE: <flags> {<ELF files>} |
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# @RETURN: Shell true if we succeed, shell false otherwise |
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# @DESCRIPTION: |
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# Marks <ELF files> with provided PaX <flags> |
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# |
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# Flags are passed directly to the utilities unchanged |
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# |
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# p: disable PAGEEXEC P: enable PAGEEXEC |
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# e: disable EMUTRAMP E: enable EMUTRAMP |
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# m: disable MPROTECT M: enable MPROTECT |
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# r: disable RANDMMAP R: enable RANDMMAP |
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# s: disable SEGMEXEC S: enable SEGMEXEC |
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# |
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# Default flags are 'PeMRS', which are the most restrictive settings. Refer |
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# to http://pax.grsecurity.net/ for details on what these flags are all about. |
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# |
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# Please confirm any relaxation of restrictions with the Gentoo Hardened team. |
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# Either ask on the gentoo-hardened mailing list, or CC/assign hardened@g.o on |
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# the bug report. |
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pax-mark() { |
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|
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local f # loop over paxables |
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local flags # pax flags |
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local ret=0 # overal return code of this function |
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|
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# Only the actual PaX flags and z are accepted |
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# 1. The leading '-' is optional |
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# 2. -C -c only make sense for paxctl, but are unnecessary |
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# because we progressively do -q -qc -qC |
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# 3. z is allowed for the default |
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|
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flags="${1//[!zPpEeMmRrSs]}" |
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[[ "${flags}" ]] || return 0 |
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shift |
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|
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# z = default. For XATTR_PAX, the default is no xattr field at all |
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local dodefault="" |
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[[ "${flags//[!z]}" ]] && dodefault="yes" |
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|
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if has PT ${PAX_MARKINGS}; then |
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_pax_list_files einfo "$@" |
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for f in "$@"; do |
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|
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#First try paxctl -> this might try to create/convert program headers |
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if type -p paxctl > /dev/null; then |
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einfo "PT PaX marking -${flags} ${f} with paxctl" |
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# First, try modifying the existing PAX_FLAGS header |
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paxctl -q${flags} "${f}" && continue |
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# Second, try creating a PT_PAX header (works on ET_EXEC) |
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# Even though this is less safe, most exes need it, eg bug #463170 |
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paxctl -qC${flags} "${f}" && continue |
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# Third, try stealing the (unused under PaX) PT_GNU_STACK header |
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paxctl -qc${flags} "${f}" && continue |
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fi |
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|
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#Next try paxctl-ng -> this will not create/convert any program headers |
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if type -p paxctl-ng > /dev/null && paxctl-ng -L ; then |
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einfo "PT PaX marking -${flags} ${f} with paxctl-ng" |
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flags="${flags//z}" |
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[[ ${dodefault} == "yes" ]] && paxctl-ng -L -z "${f}" |
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[[ "${flags}" ]] || continue |
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paxctl-ng -L -${flags} "${f}" && continue |
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fi |
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|
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#Finally fall back on scanelf |
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if type -p scanelf > /dev/null && [[ ${PAX_MARKINGS} != "none" ]]; then |
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scanelf -Xxz ${flags} "$f" |
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#We failed to set PT_PAX flags |
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elif [[ ${PAX_MARKINGS} != "none" ]]; then |
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elog "Failed to set PT_PAX markings -${flags} ${f}." |
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ret=1 |
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fi |
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done |
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fi |
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|
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if has XT ${PAX_MARKINGS}; then |
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_pax_list_files einfo "$@" |
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flags="${flags//z}" |
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for f in "$@"; do |
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|
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#First try paxctl-ng |
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if type -p paxctl-ng > /dev/null && paxctl-ng -l ; then |
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einfo "XT PaX marking -${flags} ${f} with paxctl-ng" |
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[[ ${dodefault} == "yes" ]] && paxctl-ng -d "${f}" |
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[[ "${flags}" ]] || continue |
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paxctl-ng -l -${flags} "${f}" && continue |
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fi |
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|
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#Next try setfattr |
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if type -p setfattr > /dev/null; then |
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[[ "${flags//[!Ee]}" ]] || flags+="e" # bug 447150 |
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einfo "XT PaX marking -${flags} ${f} with setfattr" |
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[[ ${dodefault} == "yes" ]] && setfattr -x "user.pax.flags" "${f}" |
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setfattr -n "user.pax.flags" -v "${flags}" "${f}" && continue |
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fi |
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#We failed to set XATTR_PAX flags |
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if [[ ${PAX_MARKINGS} != "none" ]]; then |
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elog "Failed to set XATTR_PAX markings -${flags} ${f}." |
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ret=1 |
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fi |
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done |
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fi |
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# [[ ${ret} == 1 ]] && elog "Executables may be killed by PaX kernels." |
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return ${ret} |
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} |
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|
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# @FUNCTION: list-paxables |
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# @USAGE: {<files>} |
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# @RETURN: Subset of {<files>} which are ELF executables or shared objects |
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# @DESCRIPTION: |
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# Print to stdout all of the <files> that are suitable to have PaX flag |
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# markings, i.e., filter out the ELF executables or shared objects from a list |
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# of files. This is useful for passing wild-card lists to pax-mark, although |
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# in general it is preferable for ebuilds to list precisely which ELFS are to |
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# be marked. Often not all the ELF installed by a package need remarking. |
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# @EXAMPLE: |
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# pax-mark -m $(list-paxables ${S}/{,usr/}bin/*) |
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list-paxables() { |
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file "$@" 2> /dev/null | grep -E 'ELF.*(executable|shared object)' | sed -e 's/: .*$//' |
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} |
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|
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# @FUNCTION: host-is-pax |
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# @RETURN: Shell true if the build process is PaX enabled, shell false otherwise |
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# @DESCRIPTION: |
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# This is intended for use where the build process must be modified conditionally |
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# depending on whether the host is PaX enabled or not. It is not intedened to |
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# determine whether the final binaries need PaX markings. Note: if procfs is |
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# not mounted on /proc, this returns shell false (e.g. Gentoo/FBSD). |
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host-is-pax() { |
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grep -qs ^PaX: /proc/self/status |
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} |
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|
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|
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# INTERNAL FUNCTIONS |
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# ------------------ |
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# |
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# These functions are for use internally by the eclass - do not use |
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# them elsewhere as they are not supported (i.e. they may be removed |
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# or their function may change arbitratily). |
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|
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# Display a list of things, one per line, indented a bit, using the |
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# display command in $1. |
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_pax_list_files() { |
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local f cmd |
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cmd=$1 |
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shift |
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for f in "$@"; do |
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${cmd} " ${f}" |
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done |
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} |
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|
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fi |
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