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164 lines
6.5 KiB
Bash
164 lines
6.5 KiB
Bash
#!/bin/sh
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# SPDX-License-Identifier: 0BSD
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###############################################################################
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#
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# Check liblzma_*.map for certain types of errors.
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#
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# liblzma_generic.map is for FreeBSD and Solaris and possibly others
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# except GNU/Linux.
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#
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# liblzma_linux.map is for GNU/Linux only. This and the matching extra code
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# in the .c files make liblzma >= 5.2.7 compatible with binaries that were
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# linked against ill-patched liblzma in RHEL/CentOS 7. By providing the
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# compatibility in official XZ Utils release will hopefully prevent people
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# from further copying the broken patch to other places when they want
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# compatibility with binaries linked on RHEL/CentOS 7. The long version
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# of the story:
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#
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# RHEL/CentOS 7 shipped with 5.1.2alpha, including the threaded
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# encoder that is behind #ifdef LZMA_UNSTABLE in the API headers.
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# In 5.1.2alpha these symbols are under XZ_5.1.2alpha in liblzma.map.
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# API/ABI compatibility tracking isn't done between development
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# releases so newer releases didn't have XZ_5.1.2alpha anymore.
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#
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# Later RHEL/CentOS 7 updated xz to 5.2.2 but they wanted to keep
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# the exported symbols compatible with 5.1.2alpha. After checking
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# the ABI changes it turned out that >= 5.2.0 ABI is backward
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# compatible with the threaded encoder functions from 5.1.2alpha
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# (but not vice versa as fixes and extensions to these functions
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# were made between 5.1.2alpha and 5.2.0).
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#
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# In RHEL/CentOS 7, XZ Utils 5.2.2 was patched with
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# xz-5.2.2-compat-libs.patch to modify liblzma.map:
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#
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# - XZ_5.1.2alpha was added with lzma_stream_encoder_mt and
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# lzma_stream_encoder_mt_memusage. This matched XZ Utils 5.1.2alpha.
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#
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# - XZ_5.2 was replaced with XZ_5.2.2. It is clear that this was
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# an error; the intention was to keep using XZ_5.2 (XZ_5.2.2
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# has never been used in XZ Utils). So XZ_5.2.2 lists all
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# symbols that were listed under XZ_5.2 before the patch.
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# lzma_stream_encoder_mt and _mt_memusage are included too so
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# they are listed both here and under XZ_5.1.2alpha.
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#
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# The patch didn't add any __asm__(".symver ...") lines to the .c
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# files. Thus the resulting liblzma.so exports the threaded encoder
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# functions under XZ_5.1.2alpha only. Listing the two functions
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# also under XZ_5.2.2 in liblzma.map has no effect without
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# matching .symver lines.
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#
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# The lack of XZ_5.2 in RHEL/CentOS 7 means that binaries linked
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# against unpatched XZ Utils 5.2.x won't run on RHEL/CentOS 7.
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# This is unfortunate but this alone isn't too bad as the problem
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# is contained within RHEL/CentOS 7 and doesn't affect users
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# of other distributions. It could also be fixed internally in
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# RHEL/CentOS 7.
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#
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# The second problem is more serious: In XZ Utils 5.2.2 the API
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# headers don't have #ifdef LZMA_UNSTABLE for obvious reasons.
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# This is true in RHEL/CentOS 7 version too. Thus now programs
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# using new APIs can be compiled without an extra #define. However,
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# the programs end up depending on symbol version XZ_5.1.2alpha
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# (and possibly also XZ_5.2.2) instead of XZ_5.2 as they would
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# with an unpatched XZ Utils 5.2.2. This means that such binaries
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# won't run on other distributions shipping XZ Utils >= 5.2.0 as
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# they don't provide XZ_5.1.2alpha or XZ_5.2.2; they only provide
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# XZ_5.2 (and XZ_5.0). (This includes RHEL/CentOS 8 as the patch
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# luckily isn't included there anymore with XZ Utils 5.2.4.)
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#
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# Binaries built by RHEL/CentOS 7 users get distributed and then
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# people wonder why they don't run on some other distribution.
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# Seems that people have found out about the patch and been copying
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# it to some build scripts, seemingly curing the symptoms but
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# actually spreading the illness further and outside RHEL/CentOS 7.
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# Adding compatibility in an official XZ Utils release should work
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# as a vaccine against this ill patch and stop it from spreading.
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# The vaccine is kept GNU/Linux-only as other OSes should be immune
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# (hopefully it hasn't spread via some build script to other OSes).
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#
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# Author: Lasse Collin
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#
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###############################################################################
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LC_ALL=C
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export LC_ALL
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STATUS=0
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cd "$(dirname "$0")"
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# Get the list of symbols that aren't defined in liblzma_generic.map.
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SYMS=$(sed -n 's/^extern LZMA_API([^)]*) \([a-z0-9_]*\)(.*$/\1;/p' \
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api/lzma/*.h \
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| sort \
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| grep -Fve "$(sed '/[{}:*]/d;/^$/d;s/^ //' liblzma_generic.map)")
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# Check that there are no old alpha or beta versions listed.
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VER=$(cd ../.. && sh build-aux/version.sh)
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NAMES=
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case $VER in
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*alpha | *beta)
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NAMES=$(sed -n 's/^.*XZ_\([^ ]*\)\(alpha\|beta\) .*$/\1\2/p' \
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liblzma_generic.map | grep -Fv "$VER")
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;;
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esac
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# Check for duplicate lines. It can catch missing dependencies.
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DUPS=$(sort liblzma_generic.map | sed '/^$/d;/^global:$/d' | uniq -d)
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# Check that liblzma_linux.map is in sync with liblzma_generic.map.
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# The RHEL/CentOS 7 compatibility symbols are in a fixed location
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# so it makes it easy to remove them for comparison with liblzma_generic.map.
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#
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# NOTE: Putting XZ_5.2 before the compatibility symbols XZ_5.1.2alpha
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# and XZ_5.2.2 in liblzma_linux.map is important: If liblzma_linux.map is
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# incorrectly used without #define HAVE_SYMBOL_VERSIONS_LINUX, only the first
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# occurrence of each function name will be used from liblzma_linux.map;
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# the rest are ignored by the linker. Thus having XZ_5.2 before the
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# compatibility symbols means that @@XZ_5.2 will be used for the symbols
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# listed under XZ_5.2 {...} and the same function names later in
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# the file under XZ_5.1.2alpha {...} and XZ_5.2.2 {...} will be
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# ignored (@XZ_5.1.2alpha or @XZ_5.2.2 won't be added at all when
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# the #define HAVE_SYMBOL_VERSIONS_LINUX isn't used).
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IN_SYNC=
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if ! sed '111,125d' liblzma_linux.map \
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| cmp -s - liblzma_generic.map; then
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IN_SYNC=no
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fi
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# Print error messages if needed.
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if test -n "$SYMS$NAMES$DUPS$IN_SYNC"; then
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echo
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echo 'validate_map.sh found problems from liblzma_*.map:'
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echo
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if test -n "$SYMS"; then
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echo 'liblzma_generic.map lacks the following symbols:'
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echo "$SYMS"
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echo
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fi
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if test -n "$NAMES"; then
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echo 'Obsolete alpha or beta version names:'
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echo "$NAMES"
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echo
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fi
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if test -n "$DUPS"; then
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echo 'Duplicate lines:'
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echo "$DUPS"
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echo
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fi
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if test -n "$IN_SYNC"; then
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echo "liblzma_generic.map and liblzma_linux.map aren't in sync"
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echo
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fi
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STATUS=1
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fi
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# Exit status is 1 if problems were found, 0 otherwise.
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exit "$STATUS"
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