[4/4] Add --disable-major-minor-libraries configure option
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Commit Message
This option can be used to increase compatibility with package managers.
The name was choosen to avoid confusion with all the different versions
(glibc release, soname versions, symbol versions).
This patch makes all uses of -$(version).so conditional on the new
$(major-minor-libraries) flag. The alternative install targets write
the implementation DSOs directly to the locations determined by their
sonames, skipping the creation of an intermediate symbolic link.
install-symbolic-link in Makerules is updated not to require the
$(symbolic-link-list) file because it may not exist in
--disable-major-minor-libraries mode.
---
INSTALL | 10 ++++++++++
Makefile | 4 +++-
Makerules | 26 +++++++++++++++++++++++++-
config.make.in | 1 +
configure | 15 +++++++++++++++
configure.ac | 7 +++++++
elf/Makefile | 8 +++++++-
manual/install.texi | 9 +++++++++
8 files changed, 77 insertions(+), 3 deletions(-)
Comments
* Joseph Myers:
> This needs a NEWS entry.
What about this?
* glibc can now be configured with the --disable-major-minor-libraries
option. In this case, the various shared objects that are part of
glibc will be installed under their ABI sonames (such as libc.so.6)
rather than version-specific file names (such as libc-2.34.so). As
before, by default, glibc installs them as version-specific file
names, with the ABI sonames added as symbolic links. The
--disable-major-minor-libraries option enables safer downgrades with
package managers which delete removed files very late, after invoking
ldconfig.
Indepdently of the implementation of the patch, do you think this is
something that needs to be configurable, or can we remove versioned file
names altogether?
Thanks,
Florian
On Wed, 9 Jun 2021, Florian Weimer via Libc-alpha wrote:
> * Joseph Myers:
>
> > This needs a NEWS entry.
>
> What about this?
>
> * glibc can now be configured with the --disable-major-minor-libraries
> option. In this case, the various shared objects that are part of
> glibc will be installed under their ABI sonames (such as libc.so.6)
> rather than version-specific file names (such as libc-2.34.so). As
> before, by default, glibc installs them as version-specific file
> names, with the ABI sonames added as symbolic links. The
> --disable-major-minor-libraries option enables safer downgrades with
> package managers which delete removed files very late, after invoking
> ldconfig.
That seems reasonable (if we have this option at all).
> Indepdently of the implementation of the patch, do you think this is
> something that needs to be configurable, or can we remove versioned file
> names altogether?
I don't know why we have the versioned file names, but my guess would be
it was intended to help with downgrades after a non-package-manager
installation directly into the root filesystem went wrong (someone could
try to use sln to recover by linking back to the older-version files).
I don't think we should expect installation directly into the root
filesystem by "make install" to work reliably anyway, let alone provide a
downgrade mechanism, so I don't see the need to support versioned file
names any more.
@@ -199,6 +199,16 @@ if 'CFLAGS' is specified it must enable optimization. For example:
RELRO and a read-only global offset table (GOT), at the cost of
slightly increased program load times.
+'--disable-major-minor-libraries'
+ Do not install shared objects under file names that contain the
+ major and minor version of the GNU C Library. By default, such
+ names are used, and the names defined by the ABI are provided as
+ symbolic links only. This causes problems with certain package
+ managers during library upgrades and (in particular) downgrades, so
+ this option can be used to install these shared objects directly
+ under their ABI-defined names, without an additional indirection
+ via symbolic links.
+
'--enable-pt_chown'
The file 'pt_chown' is a helper binary for 'grantpt' (*note
Pseudo-Terminals: Allocation.) that is installed setuid root to fix
@@ -112,7 +112,9 @@ ifeq (yes,$(build-shared))
install: install-symbolic-link
.PHONY: install-symbolic-link
install-symbolic-link: subdir_install
- $(symbolic-link-prog) $(symbolic-link-list)
+ if test -e $(symbolic-link-list) ; then \
+ $(symbolic-link-prog) $(symbolic-link-list); \
+ fi
rm -f $(symbolic-link-list)
install:
@@ -989,6 +989,14 @@ versioned := $(strip $(foreach so,$(install-lib.so),\
install-lib.so-versioned := $(filter $(versioned), $(install-lib.so))
install-lib.so-unversioned := $(filter-out $(versioned), $(install-lib.so))
+# $(install-major-minor-libraries) is used within install-lib-nosubdir
+# to trigger installation of the actual implementation file.
+ifeq (yes,$(major-minor-libraries))
+install-major-minor-libraries = $(inst_slibdir)/$(L:.so=)-$(version).so
+else
+install-major-minor-libraries =
+endif
+
# For libraries whose soname have version numbers, we install three files:
# $(inst_libdir)/libfoo.so -- for linking, symlink or ld script
# $(inst_slibdir)/libfoo.so.NN -- for loading by SONAME, symlink
@@ -996,7 +1004,7 @@ install-lib.so-unversioned := $(filter-out $(versioned), $(install-lib.so))
install-lib-nosubdir: $(install-lib.so-unversioned:%=$(inst_slibdir)/%) \
$(foreach L,$(install-lib.so-versioned),\
$(inst_libdir)/$L \
- $(inst_slibdir)/$(L:.so=)-$(version).so \
+ $(install-major-minor-libraries) \
$(inst_slibdir)/$L$($L-version))
# Install all the unversioned shared libraries.
@@ -1049,6 +1057,7 @@ endef
endif
ifdef libc.so-version
+ifeq (yes,$(major-minor-libraries))
# For a library specified to be version N, install three files:
# libc.so -> libc.so.N (e.g. libc.so.6)
# libc.so.6 -> libc-VERSION.so (e.g. libc-1.10.so)
@@ -1058,6 +1067,11 @@ $(inst_slibdir)/libc.so$(libc.so-version): $(inst_slibdir)/libc-$(version).so \
$(make-shlib-link)
$(inst_slibdir)/libc-$(version).so: $(common-objpfx)libc.so $(+force)
$(do-install-program)
+else # !$(major-minor-libraries)
+$(inst_slibdir)/libc.so$(libc.so-version): $(common-objpfx)libc.so $(+force)
+ $(do-install-program)
+endif # !$(major-minor-libraries)
+
install: $(inst_slibdir)/libc.so$(libc.so-version)
# This fragment of linker script gives the OUTPUT_FORMAT statement
@@ -1124,6 +1138,7 @@ include $(o-iterator)
generated += $(foreach o,$(versioned),$o$($o-version))
+ifeq (yes,$(major-minor-libraries))
define o-iterator-doit
$(inst_slibdir)/$o$($o-version): $(inst_slibdir)/$(o:.so=)-$(version).so \
$(+force);
@@ -1138,6 +1153,15 @@ $(inst_slibdir)/$(o:.so=)-$(version).so: $(objpfx)$o $(+force);
endef
object-suffixes-left := $(versioned)
include $(o-iterator)
+
+else # !$(major-minor-libraries)
+define o-iterator-doit
+$(inst_slibdir)/$o$($o-version): $(objpfx)$o $(+force);
+ $$(do-install-program)
+endef
+object-suffixes-left := $(versioned)
+include $(o-iterator)
+endif # !$(major-minor-libraries)
endif # ifneq (,$(versioned))
define do-install-so
@@ -71,6 +71,7 @@ have-libcap = @have_libcap@
have-cc-with-libunwind = @libc_cv_cc_with_libunwind@
fno-unit-at-a-time = @fno_unit_at_a_time@
bind-now = @bindnow@
+major-minor-libraries = @major_minor_libraries@
have-hash-style = @libc_cv_hashstyle@
use-default-link = @use_default_link@
have-cxx-thread_local = @libc_cv_cxx_thread_local@
@@ -681,6 +681,7 @@ experimental_malloc
enable_werror
all_warnings
force_install
+major_minor_libraries
bindnow
hardcoded_path_in_tests
enable_timezone_tools
@@ -774,6 +775,7 @@ enable_hidden_plt
enable_bind_now
enable_stack_protector
enable_static_nss
+enable_major_minor_libraries
enable_force_install
enable_maintainer_mode
enable_kernel
@@ -1435,6 +1437,10 @@ Optional Features:
Use -fstack-protector[-all|-strong] to detect glibc
buffer overflows
--enable-static-nss build static NSS modules [default=no]
+ --enable-major-minor-libraries
+ install most shared objects under names based on the
+ glibc version, with symbolic links to them
+ [default=yes]
--disable-force-install don't force installation of files from this package,
even if they are older than the installed files
--enable-maintainer-mode
@@ -3480,6 +3486,15 @@ if test x"$static_nss" = xyes || test x"$shared" = xno; then
fi
+# Check whether --enable-major-minor-libraries was given.
+if test "${enable_major_minor_libraries+set}" = set; then :
+ enableval=$enable_major_minor_libraries; major_minor_libraries=$enableval
+else
+ major_minor_libraries=yes
+fi
+
+
+
# Check whether --enable-force-install was given.
if test "${enable_force_install+set}" = set; then :
enableval=$enable_force_install; force_install=$enableval
@@ -242,6 +242,13 @@ if test x"$static_nss" = xyes || test x"$shared" = xno; then
AC_DEFINE(DO_STATIC_NSS)
fi
+AC_ARG_ENABLE([major-minor-libraries],
+ AC_HELP_STRING([--enable-major-minor-libraries],
+ [install most shared objects under names based on the glibc version, with symbolic links to them @<:@default=yes@:>@]),
+ [major_minor_libraries=$enableval],
+ [major_minor_libraries=yes])
+AC_SUBST(major_minor_libraries)
+
AC_ARG_ENABLE([force-install],
AS_HELP_STRING([--disable-force-install],
[don't force installation of files from this package, even if they are older than the installed files]),
@@ -628,6 +628,7 @@ $(objpfx)trusted-dirs.st: Makefile $(..)Makeconfig
CPPFLAGS-dl-load.c += -I$(objpfx). -I$(csu-objpfx).
ifeq (yes,$(build-shared))
+ifeq (yes,$(major-minor-libraries))
$(inst_slibdir)/$(rtld-version-installed-name): $(objpfx)ld.so $(+force)
$(make-target-directory)
$(do-install-program)
@@ -637,11 +638,16 @@ $(inst_rtlddir)/$(rtld-installed-name): \
$(inst_slibdir)/libc-$(version).so
$(make-target-directory)
$(make-shlib-link)
+else # !$(major-minor-libraries)
+$(inst_rtlddir)/$(rtld-installed-name): $(objpfx)ld.so $(+force)
+ $(make-target-directory)
+ $(do-install-program)
+endif # !$(major-minor-libraries)
# Special target called by parent to install just the dynamic linker.
.PHONY: ldso_install
ldso_install: $(inst_rtlddir)/$(rtld-installed-name)
-endif
+endif # $(build-shared)
# Workarounds for ${exec_prefix} expansion in configure variables.
@@ -226,6 +226,15 @@ provides additional security hardening because it enables full RELRO
and a read-only global offset table (GOT), at the cost of slightly
increased program load times.
+@item --disable-major-minor-libraries
+Do not install shared objects under file names that contain the major
+and minor version of @theglibc. By default, such names are used, and
+the names defined by the ABI are provided as symbolic links only. This
+causes problems with certain package managers during library upgrades
+and (in particular) downgrades, so this option can be used to install
+these shared objects directly under their ABI-defined names, without an
+additional indirection via symbolic links.
+
@pindex pt_chown
@findex grantpt
@item --enable-pt_chown