diff options
| -rwxr-xr-x | lib/check_sym | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/lib/check_sym b/lib/check_sym new file mode 100755 index 00000000000..1b40b208f65 --- /dev/null +++ b/lib/check_sym @@ -0,0 +1,268 @@ +#!/bin/ksh +# +# check_sym -- compare the symbols and external function references in two +# versions of a shared library +# +# SYNOPSIS +# check_sym [-ch] [old [new]] +# +# DESCRIPTION +# Library developers need to be aware when they have changed the +# ABI of a library. To assist them, check_sym examines two versions +# of a shared library and reports changes to the following: +# * the set of exported symbols and their strengths +# * the set of undefined symbols referenced +# * the set of lazily-resolved functions (PLT) +# +# In each case, additions and removals are reported; for exported +# symbols it also reports when a symbol is weakened or strengthened. +# +# The shared libraries to compare can be specified on the +# command-line. Otherwise, check_sym expects to be run from the +# source directory of a library, with a shlib_version file specifying +# the version being built and the new library in the obj subdirectory. +# If the old library to compare against, wasn't specified either then +# check_sym will take the highest version of that library in the +# *current* directory, or the highest version of that library in +# /usr/lib if it wasn't present in the current directory. +# +# check_sym uses fixed names in /tmp for its intermediate files, +# as they contain useful details for those trying to understand +# what changed. If any of them cannot be created by the user, +# the command will fail. The files can be cleaned up using +# the -c option. +# +# +# The *basic* rules of thumb for library versions are: if you +# * stop exporting a symbol, or +# * change the size of a data symbol (not reported by check_sym) +# * start exporting a symbol that an inter-dependent library needs +# then you need to bump the MAJOR version of the library. +# +# Otherwise, if you: +# * start exporting a symbol +# then you need to bump the MINOR version of the library. +# +# SEE ALSO +# readelf(1), elf(5) +# +# AUTHORS +# Philip Guenther <guenther@openbsd.org> +# +# CAVEATS +# The elf format is infinitely extendable, but check_sym only +# handles a few weirdnesses. Running it on or against new archs +# may result in meaningless results. +# +# BUGS +# Should report changes in the size of exported data objects. +# + +get_lib_name() +{ + sed -n 's/^[ ]*LIB[ ]*=[ ]*\([^ ]*\).*/\1/p' "$@" +} + +pick_highest() +{ + old= + omaj=-1 + omin=0 + for i + do + [[ -f $i ]] || continue + maj=${i%.*}; maj=${maj##*.} + min=${i##*.} + if [[ $maj -gt $omaj || ( $maj -eq $omaj && $min -gt $omin ) ]] + then + old=$i + omaj=$maj + omin=$min + fi + done + [[ $old != "" ]] +} + +cpu=$(uname -p) +if [[ $cpu = mips64* ]] +then + file_list=/tmp/{D{,S,W,Y},J,S,U,d,j,r,s}{1,2} +else + file_list=/tmp/{D{,S,W},J,S,U,d,j,r,s}{1,2} +fi + +if [[ $1 = "-h" ]] +then + echo "usage: $0 [-ch] [old [new]]" + exit 0 +elif [[ $1 = "-c" ]] +then + rm -f $file_list + exit 0 +fi + +# Old library? +if [[ $1 = ?(*/)lib*.so* ]] +then + if [[ ! -f $1 ]] + then + echo "$1 doesn't exist" >&2 + exit 1 + fi + old=$1 + lib=${old##*/} + lib=${lib%%.so.*} + shift +else + # try determining it from the current directory + if [[ -f Makefile ]] && lib=$(get_lib_name Makefile) && + [[ $lib != "" ]] + then + lib=lib$lib + else + lib=libc + fi + + # Is there a copy of that lib in the current directory? + # If so, use the highest numbered one + if ! pick_highest $lib.so.* && ! pick_highest /usr/lib/$lib.so.* + then + echo "unable to find $lib.so.*" >&2 + exit 1 + fi +fi + +# New library? +if [[ $1 = ?(*/)lib*.so* ]] +then + if [[ ! -f $1 ]] + then + echo "$1 doesn't exist" >&2 + exit 1 + fi + new=$1 + shift +else + # Dig info out of the just built library + . ./shlib_version + new=obj/${lib}.so.${major}.${minor} +fi + +# Filter the output of readelf -s to be easier to parse by removing a +# field that only appears on some symbols: [<other>: 88] +# Not really arch-specific, but I've only seen it on alpha +filt_symtab() { + sed 's/\[<other>: [0-9a-f]*\]//' +} + +# precreate all the files we'll use, but with noclobber set to avoid +# symlink attacks +set -C +files= +trap 'rm -f $files' 1 2 15 ERR +for i in $file_list +do + rm -f $i + 3>$i + files="$files $i" +done +set +C + +readelf -rW $old > /tmp/r1 +readelf -rW $new > /tmp/r2 + +readelf -sW $old | filt_symtab > /tmp/s1 +readelf -sW $new | filt_symtab > /tmp/s2 + + +if [[ $cpu = mips64* ]] +then + readelf -d $old >/tmp/DY1 + readelf -d $new >/tmp/DY2 +else + rm -f /tmp/DY[12] +fi + +jump_slots() { + case $cpu in + hppa*) awk '/IPLT/ && $5 != ""{print $5}' /tmp/r$1 + ;; + mips*) gotsym=$(awk '$2 ~ /MIPS_GOTSYM/{print $3}' /tmp/DY$1) + # the $(($foo)) is to convert hex to decimal + awk -v g=$(($gotsym)) \ + '/^Symbol table ..symtab/{exit} + $1+0 >= g && $4 == "FUNC" {print $8}' /tmp/s$1 + ;; + *) awk '/JU*MP_SL/ && $5 != ""{print $5}' /tmp/r$1 + ;; + esac | sort -o /tmp/j$1 +} + +dynamic_sym() { + # truncate the output files, to guarantee they exist + >/tmp/U$1 >/tmp/DS$1 >/tmp/DW$1 >/tmp/D$1 + awk -v s=$1 '/^Symbol table ..symtab/{exit} + ! /^ *[1-9]/ {next} + $7 == "UND" {print $8 | ("sort -o /tmp/U" s); next } + $5 == "GLOBAL" {print $8 | ("sort -o /tmp/DS" s) } + $5 == "WEAK" {print $8 | ("sort -o /tmp/DW" s) } + $5 != "LOCAL" {print $8 | ("sort -o /tmp/D" s) } + {print $4, $5, $6, $8}' /tmp/s$1 | sort -o /tmp/d$1 +# awk -v s=$1 '$2 == "GLOBAL" {print $4 | ("sort -o /tmp/DS" s) } +# $2 == "WEAK" {print $4 | ("sort -o /tmp/DW" s) } +# $1 != "SECTION"{print $4}' /tmp/d$1 | sort -o /tmp/D$1 +} + +static_sym() { + awk '/^Symbol table ..symtab/{s=1} + /LOCAL/{next} + s&&/^ *[1-9]/{print $4, $5, $6, $8}' /tmp/s$1 | sort -o /tmp/S$1 +} + +output_if_not_empty() { + leader=$1 + shift + if "$@" | grep -q . + then + echo "$leader" + "$@" | sed 's:^: :' + echo + fi +} + + +for i in 1 2 +do + jump_slots $i + dynamic_sym $i + static_sym $i + comm -23 /tmp/j$i /tmp/U$i >/tmp/J$i +done + +echo "$old --> $new" +if cmp -s /tmp/d[12] +then + printf "No dynamic export changes\n" +else + printf "Dynamic export changes:\n" + output_if_not_empty "added:" comm -13 /tmp/D[12] + output_if_not_empty "removed:" comm -23 /tmp/D[12] + output_if_not_empty "weakened:" comm -12 /tmp/DS1 /tmp/DW2 + output_if_not_empty "strengthened:" comm -12 /tmp/DW1 /tmp/DS2 +fi +if ! cmp -s /tmp/U[12] +then + printf "External reference changes:\n" + output_if_not_empty "added:" comm -13 /tmp/U[12] + output_if_not_empty "removed:" comm -23 /tmp/U[12] +fi + +if false; then + printf "\nReloc counts:\nbefore:\n" + grep ^R /tmp/r1 + printf "\nafter:\n" + grep ^R /tmp/r2 +fi + +output_if_not_empty "PLT added:" comm -13 /tmp/J1 /tmp/J2 +output_if_not_empty "PLT removed:" comm -23 /tmp/J1 /tmp/J2 |