1#!/bin/sh 2# SPDX-License-Identifier: 0BSD 3 4############################################################################### 5# 6# Check liblzma_*.map for certain types of errors. 7# 8# liblzma_generic.map is for FreeBSD and Solaris and possibly others 9# except GNU/Linux. 10# 11# liblzma_linux.map is for GNU/Linux only. This and the matching extra code 12# in the .c files make liblzma >= 5.2.7 compatible with binaries that were 13# linked against ill-patched liblzma in RHEL/CentOS 7. By providing the 14# compatibility in official XZ Utils release will hopefully prevent people 15# from further copying the broken patch to other places when they want 16# compatibility with binaries linked on RHEL/CentOS 7. The long version 17# of the story: 18# 19# RHEL/CentOS 7 shipped with 5.1.2alpha, including the threaded 20# encoder that is behind #ifdef LZMA_UNSTABLE in the API headers. 21# In 5.1.2alpha these symbols are under XZ_5.1.2alpha in liblzma.map. 22# API/ABI compatibility tracking isn't done between development 23# releases so newer releases didn't have XZ_5.1.2alpha anymore. 24# 25# Later RHEL/CentOS 7 updated xz to 5.2.2 but they wanted to keep 26# the exported symbols compatible with 5.1.2alpha. After checking 27# the ABI changes it turned out that >= 5.2.0 ABI is backward 28# compatible with the threaded encoder functions from 5.1.2alpha 29# (but not vice versa as fixes and extensions to these functions 30# were made between 5.1.2alpha and 5.2.0). 31# 32# In RHEL/CentOS 7, XZ Utils 5.2.2 was patched with 33# xz-5.2.2-compat-libs.patch to modify liblzma.map: 34# 35# - XZ_5.1.2alpha was added with lzma_stream_encoder_mt and 36# lzma_stream_encoder_mt_memusage. This matched XZ Utils 5.1.2alpha. 37# 38# - XZ_5.2 was replaced with XZ_5.2.2. It is clear that this was 39# an error; the intention was to keep using XZ_5.2 (XZ_5.2.2 40# has never been used in XZ Utils). So XZ_5.2.2 lists all 41# symbols that were listed under XZ_5.2 before the patch. 42# lzma_stream_encoder_mt and _mt_memusage are included too so 43# they are listed both here and under XZ_5.1.2alpha. 44# 45# The patch didn't add any __asm__(".symver ...") lines to the .c 46# files. Thus the resulting liblzma.so exports the threaded encoder 47# functions under XZ_5.1.2alpha only. Listing the two functions 48# also under XZ_5.2.2 in liblzma.map has no effect without 49# matching .symver lines. 50# 51# The lack of XZ_5.2 in RHEL/CentOS 7 means that binaries linked 52# against unpatched XZ Utils 5.2.x won't run on RHEL/CentOS 7. 53# This is unfortunate but this alone isn't too bad as the problem 54# is contained within RHEL/CentOS 7 and doesn't affect users 55# of other distributions. It could also be fixed internally in 56# RHEL/CentOS 7. 57# 58# The second problem is more serious: In XZ Utils 5.2.2 the API 59# headers don't have #ifdef LZMA_UNSTABLE for obvious reasons. 60# This is true in RHEL/CentOS 7 version too. Thus now programs 61# using new APIs can be compiled without an extra #define. However, 62# the programs end up depending on symbol version XZ_5.1.2alpha 63# (and possibly also XZ_5.2.2) instead of XZ_5.2 as they would 64# with an unpatched XZ Utils 5.2.2. This means that such binaries 65# won't run on other distributions shipping XZ Utils >= 5.2.0 as 66# they don't provide XZ_5.1.2alpha or XZ_5.2.2; they only provide 67# XZ_5.2 (and XZ_5.0). (This includes RHEL/CentOS 8 as the patch 68# luckily isn't included there anymore with XZ Utils 5.2.4.) 69# 70# Binaries built by RHEL/CentOS 7 users get distributed and then 71# people wonder why they don't run on some other distribution. 72# Seems that people have found out about the patch and been copying 73# it to some build scripts, seemingly curing the symptoms but 74# actually spreading the illness further and outside RHEL/CentOS 7. 75# Adding compatibility in an official XZ Utils release should work 76# as a vaccine against this ill patch and stop it from spreading. 77# The vaccine is kept GNU/Linux-only as other OSes should be immune 78# (hopefully it hasn't spread via some build script to other OSes). 79# 80# Author: Lasse Collin 81# 82############################################################################### 83 84LC_ALL=C 85export LC_ALL 86 87STATUS=0 88 89cd "$(dirname "$0")" 90 91# Get the list of symbols that aren't defined in liblzma_generic.map. 92SYMS=$(sed -n 's/^extern LZMA_API([^)]*) \([a-z0-9_]*\)(.*$/\1;/p' \ 93 api/lzma/*.h \ 94 | sort \ 95 | grep -Fve "$(sed '/[{}:*]/d;/^$/d;s/^ //' liblzma_generic.map)") 96 97# Check that there are no old alpha or beta versions listed. 98VER=$(cd ../.. && sh build-aux/version.sh) 99NAMES= 100case $VER in 101 *alpha | *beta) 102 NAMES=$(sed -n 's/^.*XZ_\([^ ]*\)\(alpha\|beta\) .*$/\1\2/p' \ 103 liblzma_generic.map | grep -Fv "$VER") 104 ;; 105esac 106 107# Check for duplicate lines. It can catch missing dependencies. 108DUPS=$(sort liblzma_generic.map | sed '/^$/d;/^global:$/d' | uniq -d) 109 110# Check that liblzma_linux.map is in sync with liblzma_generic.map. 111# The RHEL/CentOS 7 compatibility symbols are in a fixed location 112# so it makes it easy to remove them for comparison with liblzma_generic.map. 113# 114# NOTE: Putting XZ_5.2 before the compatibility symbols XZ_5.1.2alpha 115# and XZ_5.2.2 in liblzma_linux.map is important: If liblzma_linux.map is 116# incorrectly used without #define HAVE_SYMBOL_VERSIONS_LINUX, only the first 117# occurrence of each function name will be used from liblzma_linux.map; 118# the rest are ignored by the linker. Thus having XZ_5.2 before the 119# compatibility symbols means that @@XZ_5.2 will be used for the symbols 120# listed under XZ_5.2 {...} and the same function names later in 121# the file under XZ_5.1.2alpha {...} and XZ_5.2.2 {...} will be 122# ignored (@XZ_5.1.2alpha or @XZ_5.2.2 won't be added at all when 123# the #define HAVE_SYMBOL_VERSIONS_LINUX isn't used). 124IN_SYNC= 125if ! sed '111,125d' liblzma_linux.map \ 126 | cmp -s - liblzma_generic.map; then 127 IN_SYNC=no 128fi 129 130# Print error messages if needed. 131if test -n "$SYMS$NAMES$DUPS$IN_SYNC"; then 132 echo 133 echo 'validate_map.sh found problems from liblzma_*.map:' 134 echo 135 136 if test -n "$SYMS"; then 137 echo 'liblzma_generic.map lacks the following symbols:' 138 echo "$SYMS" 139 echo 140 fi 141 142 if test -n "$NAMES"; then 143 echo 'Obsolete alpha or beta version names:' 144 echo "$NAMES" 145 echo 146 fi 147 148 if test -n "$DUPS"; then 149 echo 'Duplicate lines:' 150 echo "$DUPS" 151 echo 152 fi 153 154 if test -n "$IN_SYNC"; then 155 echo "liblzma_generic.map and liblzma_linux.map aren't in sync" 156 echo 157 fi 158 159 STATUS=1 160fi 161 162# Exit status is 1 if problems were found, 0 otherwise. 163exit "$STATUS" 164