* shlib-versions [USE_IN_LIBIO] (.*-.*-gnu-gnu*): Set earliest

	supported version for libc 0.2.90.libio to GLIBC_2.2.

	* Makeconfig (soversions.mk): Grok new third column in shlib-versions,
	and use it to emit new variable `map-firstversions'.
	* scripts/firstversions.awk: New file.
	* Makerules (Versions.all): Use scripts/firstversions.awk and
	the $(map-firstversions) value to generate a modified versions list
	that includes renames in "A = B" syntax for each version set earlier
	than the "earliest symbol version" named in shlib-versions.
	* scripts/versions.awk: Recognize "A = B" lines in the input to mean
	rename version set A to B in the output to the intermediate file.
	* scripts/abi-versions.awk: New file.
	* Makerules (abi-versions.h): New target, generated by that script.
	[$(versioning) = yes] (before-compile): Prepend abi-versions.h.
	* include/shlib-compat.h: New file, uses that generated header.

8 files changed, 198 insertions, 25 deletions

diff --git a/ChangeLog b/ChangeLog
index d8efcb08e9..9c84cb239f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,22 @@
+2000-03-19  Roland McGrath  <roland@baalperazim.frob.com>
+
+	* shlib-versions [USE_IN_LIBIO] (.*-.*-gnu-gnu*): Set earliest
+	supported version for libc 0.2.90.libio to GLIBC_2.2.
+
+	* Makeconfig (soversions.mk): Grok new third column in shlib-versions,
+	and use it to emit new variable `map-firstversions'.
+	* scripts/firstversions.awk: New file.
+	* Makerules (Versions.all): Use scripts/firstversions.awk and
+	the $(map-firstversions) value to generate a modified versions list
+	that includes renames in "A = B" syntax for each version set earlier
+	than the "earliest symbol version" named in shlib-versions.
+	* scripts/versions.awk: Recognize "A = B" lines in the input to mean
+	rename version set A to B in the output to the intermediate file.
+	* scripts/abi-versions.awk: New file.
+	* Makerules (abi-versions.h): New target, generated by that script.
+	[$(versioning) = yes] (before-compile): Prepend abi-versions.h.
+	* include/shlib-compat.h: New file, uses that generated header.
+
 2000-03-18  Roland McGrath  <roland@baalperazim.frob.com>
 
 	* Makeconfig (soversions.mk): Convert % -> # in shlib-versions
diff --git a/Makeconfig b/Makeconfig
index de1b1b186a..14a690d213 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -687,23 +687,23 @@ $(common-objpfx)soversions.mk: $(..)shlib-versions $(..)Makeconfig \
 	 for f in $$file; do \
 	   sed 's/#.*$$//;s/^[ 	]*%/#/' $$f \
 	   | $(CC) -include $(common-objpfx)config.h -E -x c - \
-	   | while read conf versions; do \
-	     test -n "$$versions" && \
+	   | while read conf version setname; do \
+	     test -n "$$version" && \
 	     test `expr '$(config-machine)-$(config-vendor)-$(config-os)' \
 			: "$$conf"` != 0 || continue; \
-	     for v in $$versions; do \
-	       lib=`echo $$v | sed 's/=.*$$//'`; \
-	       if eval "test -z \"\$$vers_lib$$lib\""; then \
-		 eval vers_lib$${lib}=yes; \
-		 number=`echo $$v | sed "s/^.*=//"`; \
-		 case $$number in \
-		   [0-9]*) echo "$$lib.so-version=.$$number"; \
-			   echo "all-sonames+=$$lib.so\$$($$lib.so-version)";;\
-		   *) echo "$$lib.so-version=$$number"; \
-		      echo "all-sonames+=\$$($$lib.so-version)";;  \
-	         esac; \
-	       fi; \
-	     done; \
+	       lib=`echo $$version | sed 's/=.*$$//'`; \
+	     if eval "test -z \"\$$versioners_lib$$lib\""; then \
+	       eval vers_lib$${lib}=yes; \
+	       number=`echo $$version | sed "s/^.*=//"`; \
+	       case $$number in \
+		 [0-9]*) echo "$$lib.so-version=.$$number"; \
+			 echo "all-sonames+=$$lib.so\$$($$lib.so-version)";;\
+		 *) echo "$$lib.so-version=$$number"; \
+		    echo "all-sonames+=\$$($$lib.so-version)";;  \
+	       esac; \
+	       test -z "$$setname" || \
+	         echo "map-firstversions+=$${lib}:$${setname}"; \
+	     fi; \
 	   done; \
 	 done;) > $@T; exit 0
 	mv -f $@T $@
diff --git a/Makerules b/Makerules
index 4d6a48742c..fefbea0342 100644
--- a/Makerules
+++ b/Makerules
@@ -1,4 +1,5 @@
-# Copyright (C) 1991,92,93,94,95,96,97,98,99 Free Software Foundation, Inc.
+# Copyright (C) 1991,92,93,94,95,96,97,98,99,2000
+#	Free Software Foundation, Inc.
 # This file is part of the GNU C Library.
 
 # The GNU C Library is free software; you can redistribute it and/or
@@ -128,6 +129,18 @@ before-compile := $(filter $(common-objpfx)mach% $(common-objpfx)hurd%,\
 		  $(filter-out $(common-objpfx)mach% $(common-objpfx)hurd%,\
 			       $(before-compile))
 
+# Even before that, we need abi-versions.h which is generated right here.
+ifeq ($(versioning),yes)
+ifndef avoid-generated
+before-compile := $(common-objpfx)abi-versions.h $(before-compile)
+$(common-objpfx)abi-versions.h: $(..)scripts/abi-versions.awk \
+				$(common-objpfx)Versions.all
+	LC_ALL=C $(AWK) -f $^ > $@T
+	mv -f $@T $@
+endif # avoid-generated
+endif # $(versioning) = yes
+
+
 # Remove existing files from `before-compile'.  Things are added there when
 # they must exist for dependency generation to work right, but once they
 # exist there is no further need for every single file to depend on them,
@@ -277,9 +290,15 @@ ifneq ($(sysd-versions-subdirs),$(all-subdirs) $(config-sysdirs))
 sysd-versions-force = FORCE
 FORCE:
 endif
-$(common-objpfx)Versions.all: $(..)Versions.def \
-			      $(wildcard $(add-ons:%=$(..)%/Versions.def))
-	cat $^ > $@T
+$(common-objpfx)Versions.all: $(..)scripts/firstversions.awk \
+	                      $(..)Versions.def \
+			      $(wildcard $(add-ons:%=$(..)%/Versions.def)) \
+			      $(common-objpfx)soversions.mk
+	{ for map in $(map-firstversions); do \
+	    echo $$map; \
+	  done | sed 's/:/ : /'; \
+	  cat $(filter-out $< $(common-objpfx)soversions.mk,$^); \
+	} | LC_ALL=C $(AWK) -f $< > $@T
 	mv -f $@T $@
 $(common-objpfx)sysd-versions: $(common-objpfx)Versions.all \
 			       $(..)scripts/versions.awk \
@@ -296,6 +315,7 @@ endif # avoid-generated
 endif # $(versioning) = yes
 endif # sysd-dirs-done
 
+
 ifndef compile-command.S
 compile-command.S = $(compile.S) $(OUTPUT_OPTION)
 endif
diff --git a/include/shlib-compat.h b/include/shlib-compat.h
new file mode 100644
index 0000000000..50fba1b957
--- /dev/null
+++ b/include/shlib-compat.h
@@ -0,0 +1,61 @@
+/* Macros for managing ABI-compatibility definitions using ELF symbol versions.
+   Copyright (C) 2000 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#ifndef _SHLIB_COMPAT_H
+#define _SHLIB_COMPAT_H	1
+
+#if defined HAVE_ELF && defined PIC && defined DO_VERSIONING
+
+#include <abi-versions.h>	/* header generated by abi-versions.awk */
+
+/* The file abi-versions.h (generated by scripts/abi-versions.awk) defines
+   symbols like `ABI_libm_GLIBC_2_0' to either 1 or 0 indicating whether or
+   not we want to build binary compatibility for e.g. the GLIBC_2.0 version
+   set into the libm shared object.  If this evaluates to zero, then there
+   is no need to compile in extra code to support this version set where it
+   has been superseded by a newer version.  The compatibility code should
+   be conditionalized with `#if SHLIB_COMPAT (libm, GLIBC_2_0)'.  */
+
+#define SHLIB_COMPAT(lib, version)	ABI_##lib##_##version
+
+/* That header also defines symbols like `VERSION_libm_GLIBC_2_1' to
+   the version set name to use for e.g. symbols first introduced into
+   libm in the GLIBC_2.1 version.  Definitions of symbols with explicit
+   versions should look like:
+   	versioned_symbol (libm, new_foo, foo, GLIBC_2_1);
+   This will define the symbol `foo' with the appropriate default version,
+   i.e. either GLIBC_2.1 or the "earliest version" specified in
+   shlib-versions if that is newer.  */
+
+#define versioned_symbol(lib, local, symbol, version) \
+  default_symbol_version (local, symbol, VERSION_##lib##_##version)
+
+#else
+
+/* Not compiling ELF shared libraries at all, so never any old versions.  */
+#define SHLIB_COMPAT(lib, version)	0
+
+/* No versions to worry about, just make this the global definition.  */
+#define versioned_symbol(lib, local, symbol, version) \
+  weak_alias (local, symbol)
+
+#endif
+
+
+#endif	/* shlib-compat.h */
diff --git a/scripts/abi-versions.awk b/scripts/abi-versions.awk
new file mode 100644
index 0000000000..0cceaad66a
--- /dev/null
+++ b/scripts/abi-versions.awk
@@ -0,0 +1,39 @@
+# Script to generate <abi-versions.h> header file from Versions.all list.
+# See include/shlib-compat.h comments for explanation.
+
+BEGIN {
+  print "/* This file is automatically generated by abi-versions.awk.";
+  print "   It defines symbols used by shlib-compat.h, which see.  */";
+  print "\n#ifndef _ABI_VERSIONS_H\n#define _ABI_VERSIONS_H";
+}
+
+NF == 2 && $2 == "{" {
+  thislib = $1;
+  gsub(/[^A-Za-z0-9_ 	]/, "_"); libid = $1;
+  printf "\n/* start %s */\n", thislib;
+  next;
+}
+$1 == "}" {
+  printf "/* end %s */\n", thislib;
+  next;
+}
+
+$2 == "=" {
+  new = $3;
+  gsub(/[^A-Za-z0-9_ 	]/, "_"); id = $1;
+  printf "#define ABI_%s_%s\t0\t/* earliest supported %s */\n", libid, id, new;
+  printf "#define VERSION_%s_%s\t%s\n", libid, id, new;
+  next;
+}
+
+{
+  vers = $1;
+  gsub(/[^A-Za-z0-9_ 	]/, "_"); id = $1;
+  printf "#define ABI_%s_%s\t1\t/* support %s */\n", libid, id, vers;
+  printf "#define VERSION_%s_%s\t%s\n", libid, id, vers;
+  next;
+}
+
+END {
+  print "\n#endif /* abi-versions.h */";
+}
diff --git a/scripts/firstversions.awk b/scripts/firstversions.awk
new file mode 100644
index 0000000000..236d90ec97
--- /dev/null
+++ b/scripts/firstversions.awk
@@ -0,0 +1,27 @@
+# Script to preprocess Versions.all lists based on "earliest version"
+# specifications in the shlib-versions file.
+
+NF == 3 && $2 == ":" { firstversion[$1] = $3; next }
+
+NF == 2 && $2 == "{" { thislib = $1; print; next }
+
+$1 == "}" {
+  if (firstversion[thislib]) {
+    # We haven't seen the stated version, but have produced
+    # others pointing to it, so we synthesize it now.
+    printf "  %s\n", firstversion[thislib];
+  }
+  print;
+  next;
+}
+
+{
+  if (! firstversion[thislib])
+    print;
+  else if ($1 == firstversion[thislib]) {
+    print;
+    firstversion[thislib] = 0;
+  }
+  else
+    print $1, "=", firstversion[thislib];
+}
diff --git a/scripts/versions.awk b/scripts/versions.awk
index 78ed73914b..086a963b25 100644
--- a/scripts/versions.awk
+++ b/scripts/versions.awk
@@ -16,7 +16,10 @@ BEGIN {
       libs[$1] = 1;
       curlib = $1;
       while (getline < defsfile && ! /^}/) {
-	versions[$1] = 1;
+        if ($2 == "=")
+	  renamed[$1] = $3;
+	else
+	  versions[$1] = 1;
       }
     }
   }
@@ -33,6 +36,7 @@ BEGIN {
 
 # This matches the beginning of the version information for a new library.
 /^[a-zA-Z0-9_.]+/ {
+  delete renamed;
   actlib = $1;
   if (!libs[$1]) {
     printf("no versions defined for %s\n", $1) > "/dev/stderr";
@@ -43,11 +47,14 @@ BEGIN {
 
 # This matches the beginning of a new version for the current library.
 /^  [A-Za-z_]/ {
-  actver = $1;
-  if (!versions[$1]) {
+  if (renamed[$1])
+    actver = renamed[$1];
+  else if (!versions[$1]) {
     printf("version %s not defined\n", $1) > "/dev/stderr";
     exit 1;
   }
+  else
+    actver = $1;
   next;
 }
 
diff --git a/shlib-versions b/shlib-versions
index abf2fd49de..f907bc7eee 100644
--- a/shlib-versions
+++ b/shlib-versions
@@ -8,8 +8,8 @@
 # This file can use cpp-style conditionals starting with % instead of #
 # to test the symbols defined in config.h by configure.
 
-# Configuration		Library versions
-# -------------		------- --------
+# Configuration		Library=version		Earliest symbol set (optional)
+# -------------		---------------		------------------------------
 
 # The interface to -lm depends mostly only on cpu, not on operating system.
 i.86-.*-.*		libm=6
@@ -33,7 +33,7 @@ alpha.*-.*-linux.*	libc=6.1
 
 # libc.so.0.2 is for the Hurd alpha release 0.2.
 %ifdef USE_IN_LIBIO /* experimental only! */
-.*-.*-gnu-gnu*		libc=0.2.90.libio
+.*-.*-gnu-gnu*		libc=0.2.90.libio	GLIBC_2.2
 %else
 .*-.*-gnu-gnu*		libc=0.2
 %endif