Remove dl-librecon.h header.

The Linux version used by i686 and m68k provide three overrrides for
generic code:

  1. DISTINGUISH_LIB_VERSIONS to print additional information when
     libc5 is used by a dependency.

  2. EXTRA_LD_ENVVARS to that enabled LD_LIBRARY_VERSION environment
     variable.

  3. EXTRA_UNSECURE_ENVVARS to add two environment variables related
     to aout support.

None are really requires, it has some decades since libc5 or aout
suppported was removed and Linux even remove support for aout files.
The LD_LIBRARY_VERSION is also dead code, dl_correct_cache_id is not
used anywhere.

Checked on x86_64-linux-gnu and i686-linux-gnu.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

NEWS

@@ -27,6 +27,8 @@ Deprecated and removed features, and other changes affecting compatibility:
   glibc is still provided through NT_GNU_ABI_TAG ELF note and also printed
   when libc.so is issued directly.
 
+* On Linux, The LD_LIBRARY_VERSION environment variable has been removed.
+
 Changes to build and runtime requirements:
 
   [Add changes to build and runtime requirements here]

elf/dl-support.c

@@ -35,7 +35,6 @@
 #include <dl-machine.h>
 #include <libc-lock.h>
 #include <dl-cache.h>
-#include <dl-librecon.h>
 #include <dl-procinfo.h>
 #include <unsecvars.h>
 #include <hp-timing.h>
@@ -157,8 +156,6 @@ struct link_map *_dl_initfirst;
 /* Descriptor to write debug messages to.  */
 int _dl_debug_fd = STDERR_FILENO;
 
-int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
-
 ElfW(auxv_t) *_dl_auxv;
 const ElfW(Phdr) *_dl_phdr;
 size_t _dl_phnum;
@@ -303,9 +300,6 @@ _dl_non_dynamic_init (void)
     {
       static const char unsecure_envvars[] =
 	UNSECURE_ENVVARS
-#ifdef EXTRA_UNSECURE_ENVVARS
-	EXTRA_UNSECURE_ENVVARS
-#endif
 	;
       const char *cp = unsecure_envvars;
 

elf/rtld.c

@@ -32,7 +32,6 @@
 #include <fpu_control.h>
 #include <hp-timing.h>
 #include <libc-lock.h>
-#include <dl-librecon.h>
 #include <unsecvars.h>
 #include <dl-cache.h>
 #include <dl-osinfo.h>
@@ -365,7 +364,6 @@ struct rtld_global_ro _rtld_global_ro attribute_relro =
     ._dl_sysinfo = DL_SYSINFO_DEFAULT,
 #endif
     ._dl_debug_fd = STDERR_FILENO,
-    ._dl_correct_cache_id = _DL_CACHE_DEFAULT_ID,
 #if !HAVE_TUNABLES
     ._dl_hwcap_mask = HWCAP_IMPORTANT,
 #endif
@@ -1692,10 +1690,6 @@ dl_main (const ElfW(Phdr) *phdr,
       if (main_map->l_ld == NULL)
 	_exit (1);
 
-      /* We allow here some platform specific code.  */
-#ifdef DISTINGUISH_LIB_VERSIONS
-      DISTINGUISH_LIB_VERSIONS;
-#endif
       _exit (has_interp ? 0 : 2);
     }
 
@@ -2648,29 +2642,14 @@ process_envvars (struct dl_main_state *state)
 		= _dl_strtoul (&envline[21], NULL) > 1;
 	    }
 	  break;
-
-	  /* We might have some extra environment variable to handle.  This
-	     is tricky due to the pre-processing of the length of the name
-	     in the switch statement here.  The code here assumes that added
-	     environment variables have a different length.  */
-#ifdef EXTRA_LD_ENVVARS
-	  EXTRA_LD_ENVVARS
-#endif
 	}
     }
 
   /* Extra security for SUID binaries.  Remove all dangerous environment
      variables.  */
-  if (__builtin_expect (__libc_enable_secure, 0))
+  if (__glibc_unlikely (__libc_enable_secure))
     {
-      static const char unsecure_envvars[] =
+      const char *nextp = UNSECURE_ENVVARS;
-#ifdef EXTRA_UNSECURE_ENVVARS
-	EXTRA_UNSECURE_ENVVARS
-#endif
-	UNSECURE_ENVVARS;
-      const char *nextp;
-
-      nextp = unsecure_envvars;
       do
 	{
 	  unsetenv (nextp);

sysdeps/generic/dl-librecon.h

@@ -1,24 +0,0 @@
-/* Optional code to distinguish library flavours.
-   Copyright (C) 1998-2022 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 Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 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
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef _DL_LIBRECON_H
-#define _DL_LIBRECON_H	1
-
-/* In the general case we don't do anything.  */
-
-#endif /* dl-librecon.h */

sysdeps/generic/ldsodefs.h

@@ -590,9 +590,6 @@ struct rtld_global_ro
   /* Default floating-point control word.  */
   EXTERN fpu_control_t _dl_fpu_control;
 
-  /* Expected cache ID.  */
-  EXTERN int _dl_correct_cache_id;
-
   /* Mask for hardware capabilities that are available.  */
   EXTERN uint64_t _dl_hwcap;
 

sysdeps/unix/sysv/linux/i386/dl-librecon.h

@@ -1,59 +0,0 @@
-/* Optional code to distinguish library flavours.
-   Copyright (C) 1998-2022 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 Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 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
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#ifndef _DL_LIBRECON_H
-
-#define DISTINGUISH_LIB_VERSIONS \
-  do									      \
-    {									      \
-      /* We have to find out whether the binary is linked against	      \
-	 libc 5 or glibc.  We do this by looking at all the DT_NEEDED	      \
-	 entries.  If one is libc.so.5 this is a libc 5 linked binary.  */    \
-      if (main_map->l_info[DT_NEEDED])					      \
-	{								      \
-	  /* We have dependencies.  */					      \
-	  const ElfW(Dyn) *d;						      \
-	  const char *strtab;						      \
-									      \
-	  strtab = (const char *) D_PTR (main_map, l_info[DT_STRTAB]);	      \
-									      \
-	  for (d = main_map->l_ld; d->d_tag != DT_NULL; ++d)		      \
-	    if (d->d_tag == DT_NEEDED					      \
-		&& strcmp (strtab + d->d_un.d_val, "libc.so.5") == 0)	      \
-	      break;							      \
-									      \
-	  /* We print a `5' or `6' depending on the outcome.  */	      \
-	  _dl_printf (d->d_tag != DT_NULL ? "5\n" : "6\n");		      \
-	}								      \
-    }									      \
-  while (0)
-
-/* Recognizing extra environment variables.  */
-#define EXTRA_LD_ENVVARS \
-  case 15:								      \
-    if (memcmp (envline, "LIBRARY_VERSION", 15) == 0)			      \
-      GLRO(dl_correct_cache_id) = envline[16] == '5' ? 2 : 3;		      \
-    break;								      \
-
-/* Extra unsecure variables.  The names are all stuffed in a single
-   string which means they have to be terminated with a '\0' explicitly.  */
-#define EXTRA_UNSECURE_ENVVARS \
-  "LD_AOUT_LIBRARY_PATH\0"						      \
-  "LD_AOUT_PRELOAD\0"
-
-#endif /* dl-librecon.h */

sysdeps/unix/sysv/linux/m68k/dl-librecon.h

@@ -1 +0,0 @@
-#include <sysdeps/unix/sysv/linux/i386/dl-librecon.h>