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432 lines
10 KiB
Bash
Executable File
432 lines
10 KiB
Bash
Executable File
#!/bin/ksh
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# $OpenBSD: check_sym,v 1.13 2024/09/03 08:49:16 tb Exp $
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#
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# Copyright (c) 2016,2019,2022 Philip Guenther <guenther@openbsd.org>
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#
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# Permission to use, copy, modify, and distribute this software for any
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# purpose with or without fee is hereby granted, provided that the above
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# copyright notice and this permission notice appear in all copies.
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#
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# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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#
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#
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# check_sym -- compare the symbols and external function references in two
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# versions of a library
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#
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# SYNOPSIS
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# check_sym [-chkSv] [old [new]]
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#
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# DESCRIPTION
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# Library developers need to be aware when they have changed the
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# ABI of a library. To assist them, check_sym examines two versions
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# of a shared library and reports changes to the following:
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# * the set of exported symbols and their strengths
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# * the set of undefined symbols referenced
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# * the set of lazily-resolved functions (PLT)
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#
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# In each case, additions and removals are reported; for exported
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# symbols it also reports when a symbol is weakened or strengthened.
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#
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# With the -S option, a similar analysis is done but for the static lib.
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#
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# The shared libraries to compare can be specified on the
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# command-line. Otherwise, check_sym expects to be run from the
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# source directory of a library with a shlib_version file specifying
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# the version being built and the new library in the obj subdirectory.
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# If the old library to compare against wasn't specified either then
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# check_sym will take the highest version of that library in the
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# *current* directory, or the highest version of that library in
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# /usr/lib if it wasn't present in the current directory.
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#
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# By default, check_sym places all its intermediate files in a
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# temporary directory and removed it on exit. They contain useful
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# details for understanding what changed, so if the -k option is used
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# they will instead be placed in /tmp/ and left behind. If any of
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# them cannot be created by the user, the command will fail. The
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# files left behind by the -k option can be cleaned up by invoking
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# check_syms with the -c option.
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#
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# The -v option enables verbose output, showing relocation counts.
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#
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# The *basic* rules of thumb for library versions are: if you
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# * stop exporting a symbol, or
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# * change the size of a data symbol
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# * start exporting a symbol that an inter-dependent library needs
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# then you need to bump the MAJOR version of the library.
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#
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# Otherwise, if you:
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# * start exporting a symbol
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# then you need to bump the MINOR version of the library.
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#
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# SEE ALSO
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# readelf(1), elf(5)
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#
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# AUTHORS
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# Philip Guenther <guenther@openbsd.org>
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#
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# CAVEATS
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# The elf format is infinitely extendable, but check_sym only
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# handles a few weirdnesses. Running it on or against new archs
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# may result in meaningless results.
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#
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# BUGS
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# While the author stills find the intermediate files useful,
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# most people won't. By default they should be placed in a
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# temp directory and removed.
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#
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get_lib_name()
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{
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sed -n '/^[ ]*LIB[ ]*=/{ s/^[^=]*=[ ]*\([^ ]*\).*/\1/p; q;}' "$@"
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}
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pick_highest()
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{
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old=
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omaj=-1
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omin=0
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for i
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do
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[[ -f $i ]] || continue
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maj=${i%.*}; maj=${maj##*.}
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min=${i##*.}
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if [[ $maj -gt $omaj || ( $maj -eq $omaj && $min -gt $omin ) ]]
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then
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old=$i
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omaj=$maj
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omin=$min
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fi
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done
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[[ $old != "" ]]
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}
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fail() { echo "$*" >&2; exit 1; }
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usage()
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{
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usage="usage: check_sym [-chkSv] [old [new]]"
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[[ $# -eq 0 ]] || fail "check_sym: $*
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$usage"
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echo "$usage"
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exit 0
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}
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#
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# Output helpers
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#
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data_sym_changes()
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{
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join "$@" | awk '$2 != $3 { print $1 " " $2 " --> " $3 }'
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}
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output_if_not_empty()
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{
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leader=$1
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shift
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if "$@" | grep -q .
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then
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echo "$leader"
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"$@" | sed 's:^: :'
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echo
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fi
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}
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#
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# Dynamic library routines
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#
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dynamic_collect()
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{
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readelf -sW $old | filt_symtab > $odir/Ds1
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readelf -sW $new | filt_symtab > $odir/Ds2
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readelf -rW $old > $odir/r1
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readelf -rW $new > $odir/r2
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case $(readelf -h $new | grep '^ *Machine:') in
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*MIPS*) cpu=mips64
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gotsym1=$(readelf -d $old | awk '$2 ~ /MIPS_GOTSYM/{print $3}')
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gotsym2=$(readelf -d $new | awk '$2 ~ /MIPS_GOTSYM/{print $3}')
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;;
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*HPPA*) cpu=hppa;;
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*) cpu=dontcare;;
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esac
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}
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jump_slots()
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{
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case $cpu in
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hppa) awk '/IPLT/ && $5 != ""{print $5}' r$1
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;;
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mips64) # the $((gotsym$1)) converts hex to decimal
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awk -v g=$((gotsym$1)) \
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'/^Symbol table ..symtab/{exit}
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$6 == "PROTECTED" { next }
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$1+0 >= g && $4 == "FUNC" {print $8}' Ds$1
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;;
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*) awk '/JU*MP_SL/ && $5 != ""{print $5}' r$1
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;;
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esac | sort -o j$1
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}
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dynamic_sym()
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{
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awk -v s=$1 '/^Symbol table ..symtab/{exit}
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! /^ *[1-9]/ {next}
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$5 == "LOCAL" {next}
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$7 == "UND" {print $8 | ("sort -o DU" s); next }
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$5 == "GLOBAL" {print $8 | ("sort -o DS" s) }
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$5 == "WEAK" {print $8 | ("sort -o DW" s) }
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$4 == "OBJECT" {print $8, $3 | ("sort -o DO" s) }
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{print $8 | ("sort -o D" s)
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print $4, $5, $6, $8}' Ds$1 | sort -o d$1
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}
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static_sym()
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{
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awk '/^Symbol table ..symtab/{s=1}
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/LOCAL/{next}
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s&&/^ *[1-9]/{print $4, $5, $6, $8}' Ds$1 | sort -o s$1
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}
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dynamic_analysis()
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{
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jump_slots $1
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dynamic_sym $1
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#static_sym $1
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comm -23 j$1 DU$1 >J$1
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return 0
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}
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dynamic_output()
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{
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if cmp -s d[12] && cmp -s DO[12]
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then
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printf "No dynamic export changes\n"
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else
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printf "Dynamic export changes:\n"
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output_if_not_empty "added:" comm -13 D[12]
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output_if_not_empty "removed:" comm -23 D[12]
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output_if_not_empty "weakened:" comm -12 DS1 DW2
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output_if_not_empty "strengthened:" comm -12 DW1 DS2
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output_if_not_empty "data object sizes changes:" \
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data_sym_changes DO[12]
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fi
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if ! cmp -s DU[12]
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then
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printf "External reference changes:\n"
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output_if_not_empty "added:" comm -13 DU[12]
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output_if_not_empty "removed:" comm -23 DU[12]
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fi
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if $verbose; then
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printf "\nReloc counts:\nbefore:\n"
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grep ^R r1
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printf "\nafter:\n"
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grep ^R r2
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fi
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output_if_not_empty "PLT added:" comm -13 J[12]
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output_if_not_empty "PLT removed:" comm -23 J[12]
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}
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#
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# Static library routines
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#
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static_collect()
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{
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readelf -sW $old | filt_ret | filt_symtab > $odir/Ss1
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readelf -sW $new | filt_ret | filt_symtab > $odir/Ss2
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}
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static_analysis()
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{
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awk -v s=$1 '!/^ *[1-9]/{next}
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$5 == "LOCAL" {next}
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$7 == "UND" {print $8 | ("sort -uo SU" s); next }
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$6 == "HIDDEN" {print $8 | ("sort -uo SH" s) }
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$5 == "GLOBAL" {print $8 | ("sort -o SS" s) }
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$5 == "WEAK" {print $8 | ("sort -o SW" s) }
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$4 == "OBJECT" {print $8, $3 | ("sort -o SO" s) }
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{print $8 | ("sort -o S" s)
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print $4, $5, $6, $8}' Ss$1 | sort -o s$1
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grep -v '^_' SH$1 >Sh$1 || :
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}
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static_output()
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{
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output_if_not_empty "hidden but not reserved:" comm -13 Sh[12]
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if cmp -s s[12] && cmp -s SO[12]
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then
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printf "No static export changes\n"
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else
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printf "Static export changes:\n"
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output_if_not_empty "added:" comm -13 S[12]
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output_if_not_empty "removed:" comm -23 S[12]
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output_if_not_empty "weakened:" comm -12 SS1 SW2
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output_if_not_empty "strengthened:" comm -12 SW1 SS2
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output_if_not_empty "data object sizes changes:" \
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data_sym_changes SO[12]
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fi
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if ! cmp -s SU[12]
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then
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printf "External reference changes:\n"
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output_if_not_empty "added:" comm -13 SU[12]
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output_if_not_empty "removed:" comm -23 SU[12]
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fi
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}
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unset odir
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file_list={D{,O,S,s,W,U},J,d,j,r}{1,2}
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static_file_list={S{,H,h,O,S,U,W},U,s}{1,2}
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keep_temp=false
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dynamic=true
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static=false
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verbose=false
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do_static() { static=true dynamic=false file_list=$static_file_list; }
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while getopts :chkSv opt "$@"
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do
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case $opt in
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c) rm -f /tmp/$file_list
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exit 0;;
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h) usage;;
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k) keep_temp=true;;
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S) do_static;;
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v) verbose=true;;
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\?) usage "unknown option -- $OPTARG";;
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esac
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done
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shift $((OPTIND - 1))
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[[ $# -gt 2 ]] && usage "too many arguments"
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# Old library?
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if ! $static && [[ $1 = ?(*/)lib*.so* ]]
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then
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[[ -f $1 ]] || fail "$1 doesn't exist"
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old=$1
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lib=${old##*/}
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lib=${lib%%.so.*}
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shift
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elif [[ $1 = ?(*/)lib*.a ]]
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then
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# woo hoo, static library mode
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do_static
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if [[ -f $1 ]]
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then
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old=$1
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lib=${old##*/}
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elif [[ $1 = lib*.a && -f /usr/lib/$1 ]]
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then
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old=/usr/lib/$1
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lib=$1
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else
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fail "$1 doesn't exist"
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fi
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lib=${lib%%.a}
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shift
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else
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# try determining it from the current directory
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if [[ -f Makefile ]] && lib=$(get_lib_name Makefile) &&
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[[ $lib != "" ]]
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then
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lib=lib$lib
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else
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lib=libc
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fi
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# Is there a copy of that lib in the current directory?
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# If so, use the highest numbered one
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if ! $static &&
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! pick_highest $lib.so.* &&
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! pick_highest /usr/lib/$lib.so.*
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then
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fail "unable to find $lib.so.*"
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elif $static
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then
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old=/usr/lib/${lib}.a
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[[ -f $old ]] || fail "$old doesn't exist"
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fi
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fi
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# New library?
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if [[ $1 = ?(*/)lib*.so* ]] ||
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{ $static && [[ $1 = ?(*/)lib*.a ]]; }
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then
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new=$1
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shift
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elif $static
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then
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new=obj/${lib}.a
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else
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# Dig info out of the just built library
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. ./shlib_version
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new=obj/${lib}.so.${major}.${minor}
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fi
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[[ -f $new ]] || fail "$new doesn't exist"
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# Filter the output of readelf -s to be easier to parse by removing a
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# field that only appears on some symbols: [<other>: 88]
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# Not really arch-specific, but I've only seen it on alpha
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filt_symtab() { sed 's/\[<other>: [0-9a-f]*\]//'; }
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filt_ret() { egrep -v ' (__retguard_[0-9]+|__llvm_retpoline_[a-z]+[0-9]*)$'; }
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if $keep_temp
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then
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# precreate all the files we'll use, but with noclobber set to avoid
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# symlink attacks
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odir=/tmp
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files=
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trap 'ret=$?; rm -f $files; exit $ret' 1 2 15 ERR
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else
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trap 'ret=$?; rm -rf "$odir"; exit $ret' 0 1 2 15 ERR
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odir=$(mktemp -dt check_sym.XXXXXXXXXX)
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fi
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set -C
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for i in $odir/$file_list
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do
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rm -f $i
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3>$i
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files="$files $i"
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done
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set +C
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#
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# Collect data
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#
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$dynamic && dynamic_collect
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$static && static_collect
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# Now that we're done accessing $old and $new (which could be
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# relative paths), chdir into our work directory, whatever it is
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cd $odir
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#
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# Do The Job
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#
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for i in 1 2
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do
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$dynamic && dynamic_analysis $i
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$static && static_analysis $i
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done
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{
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echo "$old --> $new"
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! $dynamic || dynamic_output
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! $static || static_output
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}
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