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[4/4] Install shared objects under their ABI names

Message ID eae14c3d57b3fef43892ca304f2d8017555e8447.1623312996.git.fweimer@redhat.com
State New
Headers show
Series Do not install shared objects under versioned names | expand


Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent

Commit Message

Florian Weimer June 10, 2021, 8:23 a.m. UTC
Previously, the installed objects were named like libc-2.33.so,
and the ABI soname libc.so.6 was just a symbolic link.

The Makefile targets to install these symbolic links are no longer
needed after this, so they are removed with this commit.  The more
general $(make-link) command (which invokes scripts/rellns-sh) is
retained because other symbolic links are still needed.
 INSTALL      | 10 ++++++++++
 Makefile     |  6 ------
 Makerules    | 45 +++++----------------------------------------
 NEWS         |  8 ++++++++
 elf/Makefile | 10 ++--------
 5 files changed, 25 insertions(+), 54 deletions(-)
diff mbox series


diff --git a/INSTALL b/INSTALL
index bc761ab98b..ed5f66489b 100644
@@ -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.
+     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.
      The file 'pt_chown' is a helper binary for 'grantpt' (*note
      Pseudo-Terminals: Allocation.) that is installed setuid root to fix
diff --git a/Makefile b/Makefile
index 242d36de91..c115c652a0 100644
--- a/Makefile
+++ b/Makefile
@@ -109,12 +109,6 @@  elf/ldso_install:
 # Ignore the error if we cannot update /etc/ld.so.cache.
 ifeq (no,$(cross-compiling))
 ifeq (yes,$(build-shared))
-install: install-symbolic-link
-.PHONY: install-symbolic-link
-install-symbolic-link: subdir_install
-	$(symbolic-link-prog) $(symbolic-link-list)
-	rm -f $(symbolic-link-list)
 	-test ! -x $(elf-objpfx)ldconfig || LC_ALL=C \
 	  $(elf-objpfx)ldconfig $(addprefix -r ,$(install_root)) \
diff --git a/Makerules b/Makerules
index d3f29d0b89..6efff78fbe 100644
--- a/Makerules
+++ b/Makerules
@@ -989,14 +989,12 @@  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))
-# For libraries whose soname have version numbers, we install three files:
+# For libraries whose soname have version numbers, we install two files:
 #	$(inst_libdir)/libfoo.so	-- for linking, symlink or ld script
-#	$(inst_slibdir)/libfoo.so.NN	-- for loading by SONAME, symlink
-#	$(inst_slibdir)/libfoo-X.Y.Z.so -- the real shared object file
+#	$(inst_slibdir)/libfoo.so.NN	-- for loading by SONAME
 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 all the unversioned shared libraries.
@@ -1029,35 +1027,10 @@  ln -f $(objpfx)/$(@F) $@
-ifeq (yes,$(build-shared))
-ifeq (no,$(cross-compiling))
-symbolic-link-prog := $(elf-objpfx)sln
-symbolic-link-list := $(elf-objpfx)symlink.list
-define make-shlib-link
-echo `$(..)scripts/rellns-sh -p $< $@` $@ >> $(symbolic-link-list)
-else # cross-compiling
-# We need a definition that can be used by elf/Makefile's install rules.
-symbolic-link-prog = $(LN_S)
-ifndef make-shlib-link
-define make-shlib-link
-rm -f $@
-$(LN_S) `$(..)scripts/rellns-sh -p $< $@` $@
 ifdef libc.so-version
-# For a library specified to be version N, install three files:
-# libc.so	->	libc.so.N	(e.g. libc.so.6)
-# libc.so.6	->	libc-VERSION.so	(e.g. libc-1.10.so)
-$(inst_slibdir)/libc.so$(libc.so-version): $(inst_slibdir)/libc-$(version).so \
-					   $(+force)
-	$(make-shlib-link)
-$(inst_slibdir)/libc-$(version).so: $(common-objpfx)libc.so $(+force)
+$(inst_slibdir)/libc.so$(libc.so-version): $(common-objpfx)libc.so $(+force)
 install: $(inst_slibdir)/libc.so$(libc.so-version)
 # This fragment of linker script gives the OUTPUT_FORMAT statement
@@ -1125,15 +1098,7 @@  include $(o-iterator)
 generated += $(foreach o,$(versioned),$o$($o-version))
 define o-iterator-doit
-$(inst_slibdir)/$o$($o-version): $(inst_slibdir)/$(o:.so=)-$(version).so \
-				 $(+force);
-	$$(make-shlib-link)
-object-suffixes-left := $(versioned)
-include $(o-iterator)
-define o-iterator-doit
-$(inst_slibdir)/$(o:.so=)-$(version).so: $(objpfx)$o $(+force);
+$(inst_slibdir)/$o$($o-version): $(objpfx)$o $(+force);
 object-suffixes-left := $(versioned)
diff --git a/NEWS b/NEWS
index 1bf3daa502..1634e20ce5 100644
--- a/NEWS
+++ b/NEWS
@@ -48,6 +48,14 @@  Deprecated and removed features, and other changes affecting compatibility:
 * The function pthread_yield has been deprecated; programs should use
   the equivalent standard function sched_yield instead.
+* Previously, glibc installed its various shared objects under versioned
+  file names such as libc-2.33.so.  The ABI sonames (e.g., libc.so.6)
+  were provided as symbolic links.  Starting with glibc 2.34, the shared
+  objects are installed under their ABI sonames directly, without
+  symbolic links.  This increases compatibility with distribution
+  package managers that delete removed files late during the package
+  upgrade or downgrade process.
 Changes to build and runtime requirements:
 * On Linux, the shm_open, sem_open, and related functions now expect the
diff --git a/elf/Makefile b/elf/Makefile
index 1751f5ec67..02f634c192 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -628,20 +628,14 @@  $(objpfx)trusted-dirs.st: Makefile $(..)Makeconfig
 CPPFLAGS-dl-load.c += -I$(objpfx). -I$(csu-objpfx).
 ifeq (yes,$(build-shared))
-$(inst_slibdir)/$(rtld-version-installed-name): $(objpfx)ld.so $(+force)
+$(inst_rtlddir)/$(rtld-installed-name): $(objpfx)ld.so $(+force)
-$(inst_rtlddir)/$(rtld-installed-name): \
-  $(inst_slibdir)/$(rtld-version-installed-name) \
-  $(inst_slibdir)/libc-$(version).so
-	$(make-target-directory)
-	$(make-shlib-link)
 # Special target called by parent to install just the dynamic linker.
 .PHONY: ldso_install
 ldso_install: $(inst_rtlddir)/$(rtld-installed-name)
+endif # $(build-shared)
 # Workarounds for ${exec_prefix} expansion in configure variables.