path: root/include/libc-internal.h

/* Copyright (C) 1991,92,93,95,96,97,98,99,2000,2001 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#ifndef _LIBC_INTERNAL_H
#define _LIBC_INTERNAL_H 1

#include <features.h>

#undef __SYMBOL_PREFIX
#ifndef __SYMBOL_PREFIX
# ifdef NO_UNDERSCORES
#  define __SYMBOL_PREFIX
# else
#  define __SYMBOL_PREFIX "_"
# endif
#endif

#undef C_SYMBOL_NAME
#ifndef C_SYMBOL_NAME
# ifdef NO_UNDERSCORES
#  define C_SYMBOL_NAME(name) name
# else
#  define C_SYMBOL_NAME(name) _##name
# endif
#endif

#ifndef ASM_LINE_SEP
# define ASM_LINE_SEP ;
#endif

#ifdef HAVE_ASM_GLOBAL_DOT_NAME
# ifndef C_SYMBOL_DOT_NAME
#  if defined __GNUC__ && defined __GNUC_MINOR__ \
      && (__GNUC__ << 16) + __GNUC_MINOR__ >= (3 << 16) + 1
#   define C_SYMBOL_DOT_NAME(name) .name
#  else
#   define C_SYMBOL_DOT_NAME(name) .##name
#  endif
# endif
#endif

#ifndef __ASSEMBLER__
/* GCC understands weak symbols and aliases; use its interface where
   possible, instead of embedded assembly language.  */

/* Define ALIASNAME as a strong alias for NAME.  */
# define strong_alias(name, aliasname) _strong_alias(name, aliasname)
# define _strong_alias(name, aliasname) \
  extern __typeof (name) aliasname __attribute__ ((alias (#name)));

/* This comes between the return type and function name in
   a function definition to make that definition weak.  */
# define weak_function __attribute__ ((weak))
# define weak_const_function __attribute__ ((weak, __const__))

/* Define ALIASNAME as a weak alias for NAME.
   If weak aliases are not available, this defines a strong alias.  */
# define weak_alias(name, aliasname) _weak_alias (name, aliasname)
# define _weak_alias(name, aliasname) \
  extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));

/* Declare SYMBOL as weak undefined symbol (resolved to 0 if not defined).  */
# define weak_extern(symbol) _weak_extern (weak symbol)
# define _weak_extern(expr) _Pragma (#expr)

#else /* __ASSEMBLER__ */

# define strong_alias(name, aliasname)					\
  .global C_SYMBOL_NAME (aliasname) ;					\
  .set C_SYMBOL_NAME(aliasname),C_SYMBOL_NAME(name)

# define weak_alias(name, aliasname)					\
  .weak C_SYMBOL_NAME(aliasname) ;					\
  C_SYMBOL_NAME(aliasname) = C_SYMBOL_NAME(name)

# define weak_extern(symbol)						\
  .weak C_SYMBOL_NAME(symbol)

#endif /* __ASSEMBLER__ */

/* When a reference to SYMBOL is encountered, the linker will emit a
   warning message MSG.  */
#ifdef __HAVE_ELF__

/* We want the .gnu.warning.SYMBOL section to be unallocated.  */
# define __make_section_unallocated(section_string)	\
  asm (".section " section_string "\n\t.previous");

/* Tacking on "\n\t#" to the section name makes gcc put it's bogus
   section attributes on what looks like a comment to the assembler.  */
# ifdef __sparc__ //HAVE_SECTION_QUOTES
#  define __sec_comment "\"\n\t#\""
# else
#  define __sec_comment "\n\t#"
# endif
# ifdef __cris__
#  define link_warning(symbol, msg)
# else
#  define link_warning(symbol, msg) \
  __make_section_unallocated (".gnu.warning." #symbol) \
  static const char __evoke_link_warning_##symbol[]	\
    __attribute__ ((used, section (".gnu.warning." #symbol __sec_comment))) \
    = msg;
# endif
#else /* __HAVE_ELF__ */
# define link_warning(symbol, msg)		\
     asm (".stabs \"" msg "\",30,0,0,0\n\t"	\
          ".stabs \"" __C_SYMBOL_PREFIX__ #symbol "\",1,0,0,0\n");
#endif /* __HAVE_ELF__ */

#ifndef weak_function
/* If we do not have the __attribute__ ((weak)) syntax, there is no way we
   can define functions as weak symbols.  The compiler will emit a `.globl'
   directive for the function symbol, and a `.weak' directive in addition
   will produce an error from the assembler.  */ 
# define weak_function          /* empty */
# define weak_const_function    /* empty */
#endif

/* On some platforms we can make internal function calls (i.e., calls of
   functions not exported) a bit faster by using a different calling
   convention.  */
#if 0 /*def __i386__*/
# define internal_function __attribute__ ((regparm (3), stdcall))
#endif
#ifndef internal_function
# define internal_function      /* empty */
#endif

#ifndef NOT_IN_libc
# define IS_IN_libc 1
#endif

/* need this to unset defaults in libpthread for files that get added to libc */
#ifdef IS_IN_libc
# undef NOT_IN_libc
#endif

/* Prepare for the case that `__builtin_expect' is not available.  */
#if __GNUC__ == 2 && __GNUC_MINOR__ < 96
# define __builtin_expect(x, expected_value) (x)
#endif
#ifndef likely
# define likely(x)	__builtin_expect((!!(x)),1)
#endif
#ifndef unlikely
# define unlikely(x)	__builtin_expect((!!(x)),0)
#endif
#ifndef __LINUX_COMPILER_H
# define __LINUX_COMPILER_H
#endif
#ifndef __cast__
# define __cast__(_to)
#endif

#define attribute_unused __attribute__ ((unused))

/* The following macros are used for PLT bypassing within libc.so
   (and if needed other libraries similarly).
   First of all, you need to have the function prototyped somewhere,
   say in foo/foo.h:

   int foo (int __bar);

   If calls to foo within libc.so should always go to foo defined in libc.so,
   then in include/foo.h you add:

   libc_hidden_proto (foo)

   line and after the foo function definition:

   int foo (int __bar)
   {
     return __bar;
   }
   libc_hidden_def (foo)

   or

   int foo (int __bar)
   {
     return __bar;
   }
   libc_hidden_weak (foo)

   Simularly for global data. If references to foo within libc.so should
   always go to foo defined in libc.so, then in include/foo.h you add:

   libc_hidden_proto (foo)

   line and after foo's definition:

   int foo = INITIAL_FOO_VALUE;
   libc_hidden_data_def (foo)

   or

   int foo = INITIAL_FOO_VALUE;
   libc_hidden_data_weak (foo)

   If foo is normally just an alias (strong or weak) of some other function,
   you should use the normal strong_alias first, then add libc_hidden_def
   or libc_hidden_weak:

   int baz (int __bar)
   {
     return __bar;
   }
   strong_alias (baz, foo)
   libc_hidden_weak (foo)

   If the function should be internal to multiple objects, say ld.so and
   libc.so, the best way is to use:

   #if !defined NOT_IN_libc || defined IS_IN_rtld
   hidden_proto (foo)
   #endif

   in include/foo.h and the normal macros at all function definitions
   depending on what DSO they belong to.

   If versioned_symbol macro is used to define foo,
   libc_hidden_ver macro should be used, as in:

   int __real_foo (int __bar)
   {
     return __bar;
   }
   versioned_symbol (libc, __real_foo, foo, GLIBC_2_1);
   libc_hidden_ver (__real_foo, foo)  */

/* uClibc specific (the above comment was copied from glibc):
 * a. when ppc64 will be supported, we need changes to support:
 * strong_data_alias (used by asm hidden_data_def) / HAVE_ASM_GLOBAL_DOT_NAME
 * b. libc_hidden_proto(foo) should be added after the header having foo's prototype
 * or after extern foo... to all source files that should use the internal version
 * of foo within libc, even to the file defining foo itself, libc_hidden_def does
 * not hide __GI_foo itself, although the name suggests it (hiding is done exclusively
 * by libc_hidden_proto). The reasoning to have it after the header w/ foo's prototype is
 * to get first the __REDIRECT from original header and then create the __GI_foo alias
 * c. no versioning support, hidden[_data]_ver are noop */

/* Arrange to hide uClibc internals */
#if __GNUC_PREREQ (3, 3)
# define attribute_hidden __attribute__ ((visibility ("hidden")))
# define __hidden_proto_hiddenattr(attrs...) __attribute__ ((visibility ("hidden"), ##attrs))
#else
# define attribute_hidden
# define __hidden_proto_hiddenattr(attrs...)
#endif

/* if ppc64 will be supported, this section needs adapting due to HAVE_ASM_GLOBAL_DOT_NAME */
#if 1 /* SHARED */
# ifndef __ASSEMBLER__
#  define hidden_strong_alias(name, aliasname) _hidden_strong_alias(name, aliasname)
#  define _hidden_strong_alias(name, aliasname) \
   extern __typeof (name) aliasname __attribute__ ((alias (#name))) attribute_hidden;

#  define hidden_weak_alias(name, aliasname) _hidden_weak_alias (name, aliasname)
#  define _hidden_weak_alias(name, aliasname) \
   extern __typeof (name) aliasname __attribute__ ((weak, alias (#name))) attribute_hidden;

#  define hidden_proto(name, attrs...) __hidden_proto (name, __GI_##name, ##attrs)
#  define __hidden_proto(name, internal, attrs...) \
   extern __typeof (name) name __asm__ (__hidden_asmname (#internal)) \
   __hidden_proto_hiddenattr (attrs);
#  define __hidden_asmname(name) __hidden_asmname1 (__USER_LABEL_PREFIX__, name)
#  define __hidden_asmname1(prefix, name) __hidden_asmname2(prefix, name)
#  define __hidden_asmname2(prefix, name) #prefix name
#  define __hidden_ver1(local, internal, name) \
   extern __typeof (name) __EI_##name __asm__(__hidden_asmname (#internal)); \
   extern __typeof (name) __EI_##name __attribute__((alias (__hidden_asmname1 (,#local))))
#  define hidden_def(name)		__hidden_ver1(__GI_##name, name, name);
#  define hidden_data_def(name)		hidden_def(name)
#  define hidden_weak(name)		__hidden_ver1(__GI_##name, name, name) __attribute__((weak));
#  define hidden_data_weak(name)	hidden_weak(name)

# else /* __ASSEMBLER__ */
#  define hidden_strong_alias(name, aliasname)				\
   .global C_SYMBOL_NAME (aliasname) ;					\
   .hidden C_SYMBOL_NAME (aliasname) ;					\
   .set C_SYMBOL_NAME(aliasname),C_SYMBOL_NAME(name)

#  define hidden_weak_alias(name, aliasname)				\
   .weak C_SYMBOL_NAME(aliasname) ;					\
   .hidden C_SYMBOL_NAME(aliasname) ;					\
   C_SYMBOL_NAME(aliasname) = C_SYMBOL_NAME(name)

/* For assembly, we need to do the opposite of what we do in C:
   in assembly gcc __REDIRECT stuff is not in place, so functions
   are defined by its normal name and we need to create the
   __GI_* alias to it, in C __REDIRECT causes the function definition
   to use __GI_* name and we need to add alias to the real name.
   There is no reason to use hidden_weak over hidden_def in assembly,
   but we provide it for consistency with the C usage.
   hidden_proto doesn't make sense for assembly but the equivalent
   is to call via the HIDDEN_JUMPTARGET macro instead of JUMPTARGET.  */
#  define hidden_def(name)	hidden_strong_alias (name, __GI_##name)
#  define hidden_data_def(name)	hidden_strong_alias (name, __GI_##name)
#  define hidden_weak(name)	hidden_def (name)
#  define hidden_data_weak(name)	hidden_data_def (name)
#  define HIDDEN_JUMPTARGET(name) __GI_##name
# endif /* __ASSEMBLER__ */
#else /* SHARED */
# define hidden_strong_alias(name, aliasname)
# define hidden_weak_alias(name, aliasname)

# ifndef __ASSEMBLER__
#  define hidden_proto(name, attrs...)
# else
#  define HIDDEN_JUMPTARGET(name) name
# endif
# define hidden_def(name)
# define hidden_data_def(name)
# define hidden_weak(name)
# define hidden_data_weak(name)
#endif /* SHARED */

/* uClibc does not support versioning yet. */
#define versioned_symbol(lib, local, symbol, version) /* weak_alias(local, symbol) */
#define hidden_ver(local, name) /* strong_alias(local, __GI_##name) */
#define hidden_data_ver(local, name) /* strong_alias(local,__GI_##name) */

#if !defined NOT_IN_libc
# define libc_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libc_hidden_def(name) hidden_def (name)
# define libc_hidden_weak(name) hidden_weak (name)
# define libc_hidden_ver(local, name) hidden_ver (local, name)
# define libc_hidden_data_def(name) hidden_data_def (name)
# define libc_hidden_data_weak(name) hidden_data_weak (name)
# define libc_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libc_hidden_proto(name, attrs...)
# define libc_hidden_def(name)
# define libc_hidden_weak(name)
# define libc_hidden_ver(local, name)
# define libc_hidden_data_def(name)
# define libc_hidden_data_weak(name)
# define libc_hidden_data_ver(local, name)
#endif

#if defined NOT_IN_libc && defined IS_IN_rtld
# define rtld_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define rtld_hidden_def(name) hidden_def (name)
# define rtld_hidden_weak(name) hidden_weak (name)
# define rtld_hidden_ver(local, name) hidden_ver (local, name)
# define rtld_hidden_data_def(name) hidden_data_def (name)
# define rtld_hidden_data_weak(name) hidden_data_weak (name)
# define rtld_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define rtld_hidden_proto(name, attrs...)
# define rtld_hidden_def(name)
# define rtld_hidden_weak(name)
# define rtld_hidden_ver(local, name)
# define rtld_hidden_data_def(name)
# define rtld_hidden_data_weak(name)
# define rtld_hidden_data_ver(local, name)
#endif

#if defined NOT_IN_libc && defined IS_IN_libm
# define libm_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libm_hidden_def(name) hidden_def (name)
# define libm_hidden_weak(name) hidden_weak (name)
# define libm_hidden_ver(local, name) hidden_ver (local, name)
# define libm_hidden_data_def(name) hidden_data_def (name)
# define libm_hidden_data_weak(name) hidden_data_weak (name)
# define libm_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libm_hidden_proto(name, attrs...)
# define libm_hidden_def(name)
# define libm_hidden_weak(name)
# define libm_hidden_ver(local, name)
# define libm_hidden_data_def(name)
# define libm_hidden_data_weak(name)
# define libm_hidden_data_ver(local, name)
#endif

#if defined NOT_IN_libc && defined IS_IN_libresolv
# define libresolv_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libresolv_hidden_def(name) hidden_def (name)
# define libresolv_hidden_weak(name) hidden_weak (name)
# define libresolv_hidden_ver(local, name) hidden_ver (local, name)
# define libresolv_hidden_data_def(name) hidden_data_def (name)
# define libresolv_hidden_data_weak(name) hidden_data_weak (name)
# define libresolv_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libresolv_hidden_proto(name, attrs...)
# define libresolv_hidden_def(name)
# define libresolv_hidden_weak(name)
# define libresolv_hidden_ver(local, name)
# define libresolv_hidden_data_def(name)
# define libresolv_hidden_data_weak(name)
# define libresolv_hidden_data_ver(local, name)
#endif

#if defined NOT_IN_libc && defined IS_IN_librt
# define librt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define librt_hidden_def(name) hidden_def (name)
# define librt_hidden_weak(name) hidden_weak (name)
# define librt_hidden_ver(local, name) hidden_ver (local, name)
# define librt_hidden_data_def(name) hidden_data_def (name)
# define librt_hidden_data_weak(name) hidden_data_weak (name)
# define librt_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define librt_hidden_proto(name, attrs...)
# define librt_hidden_def(name)
# define librt_hidden_weak(name)
# define librt_hidden_ver(local, name)
# define librt_hidden_data_def(name)
# define librt_hidden_data_weak(name)
# define librt_hidden_data_ver(local, name)
#endif

#if defined NOT_IN_libc && defined IS_IN_libdl
# define libdl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libdl_hidden_def(name) hidden_def (name)
# define libdl_hidden_weak(name) hidden_weak (name)
# define libdl_hidden_ver(local, name) hidden_ver (local, name)
# define libdl_hidden_data_def(name) hidden_data_def (name)
# define libdl_hidden_data_weak(name) hidden_data_weak (name)
# define libdl_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libdl_hidden_proto(name, attrs...)
# define libdl_hidden_def(name)
# define libdl_hidden_weak(name)
# define libdl_hidden_ver(local, name)
# define libdl_hidden_data_def(name)
# define libdl_hidden_data_weak(name)
# define libdl_hidden_data_ver(local, name)
#endif

#if defined NOT_IN_libc && defined IS_IN_libintl
# define libintl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libintl_hidden_def(name) hidden_def (name)
# define libintl_hidden_weak(name) hidden_weak (name)
# define libintl_hidden_ver(local, name) hidden_ver (local, name)
# define libintl_hidden_data_def(name) hidden_data_def (name)
# define libintl_hidden_data_weak(name) hidden_data_weak (name)
# define libintl_hidden_data_ver(local, name) hidden_data_ver(local, name)
#else
# define libintl_hidden_proto(name, attrs...)
# define libintl_hidden_def(name)
# define libintl_hidden_weak(name)
# define libintl_hidden_ver(local, name)
# define libintl_hidden_data_def(name)
# define libintl_hidden_data_weak(name)
# define libintl_hidden_data_ver(local, name)
#endif

#if defined NOT_IN_libc && defined IS_IN_libnsl
# define libnsl_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libnsl_hidden_def(name) hidden_def (name)
# define libnsl_hidden_weak(name) hidden_weak (name)
# define libnsl_hidden_ver(local, name) hidden_ver (local, name)
# define libnsl_hidden_data_def(name) hidden_data_def (name)
# define libnsl_hidden_data_weak(name) hidden_data_weak (name)
# define libnsl_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libnsl_hidden_proto(name, attrs...)
# define libnsl_hidden_def(name)
# define libnsl_hidden_weak(name)
# define libnsl_hidden_ver(local, name)
# define libnsl_hidden_data_def(name)
# define libnsl_hidden_data_weak(name)
# define libnsl_hidden_data_ver(local, name)
#endif

#if defined NOT_IN_libc && defined IS_IN_libutil
# define libutil_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libutil_hidden_def(name) hidden_def (name)
# define libutil_hidden_weak(name) hidden_weak (name)
# define libutil_hidden_ver(local, name) hidden_ver (local, name)
# define libutil_hidden_data_def(name) hidden_data_def (name)
# define libutil_hidden_data_weak(name) hidden_data_weak (name)
# define libutil_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libutil_hidden_proto(name, attrs...)
# define libutil_hidden_def(name)
# define libutil_hidden_weak(name)
# define libutil_hidden_ver(local, name)
# define libutil_hidden_data_def(name)
# define libutil_hidden_data_weak(name)
# define libutil_hidden_data_ver(local, name)
#endif

#if defined NOT_IN_libc && defined IS_IN_libcrypt
# define libcrypt_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libcrypt_hidden_def(name) hidden_def (name)
# define libcrypt_hidden_weak(name) hidden_weak (name)
# define libcrypt_hidden_ver(local, name) hidden_ver (local, name)
# define libcrypt_hidden_data_def(name) hidden_data_def (name)
# define libcrypt_hidden_data_weak(name) hidden_data_weak (name)
# define libcrypt_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libcrypt_hidden_proto(name, attrs...)
# define libcrypt_hidden_def(name)
# define libcrypt_hidden_weak(name)
# define libcrypt_hidden_ver(local, name)
# define libcrypt_hidden_data_def(name)
# define libcrypt_hidden_data_weak(name)
# define libcrypt_hidden_data_ver(local, name)
#endif

#if defined NOT_IN_libc && defined IS_IN_libpthread
# define libpthread_hidden_proto(name, attrs...) hidden_proto (name, ##attrs)
# define libpthread_hidden_def(name) hidden_def (name)
# define libpthread_hidden_weak(name) hidden_weak (name)
# define libpthread_hidden_ver(local, name) hidden_ver (local, name)
# define libpthread_hidden_data_def(name) hidden_data_def (name)
# define libpthread_hidden_data_weak(name) hidden_data_weak (name)
# define libpthread_hidden_data_ver(local, name) hidden_data_ver (local, name)
#else
# define libpthread_hidden_proto(name, attrs...)
# define libpthread_hidden_def(name)
# define libpthread_hidden_weak(name)
# define libpthread_hidden_ver(local, name)
# define libpthread_hidden_data_def(name)
# define libpthread_hidden_data_weak(name)
# define libpthread_hidden_data_ver(local, name)
#endif

#ifdef __UCLIBC_BUILD_RELRO__
# define attribute_relro __attribute__ ((section (".data.rel.ro")))
#else
# define attribute_relro
#endif

#ifdef __GNUC__
# define attribute_noreturn __attribute__ ((__noreturn__))
#else
# define attribute_noreturn
#endif

#ifdef __UCLIBC_HAS_THREADS_NATIVE__
# define attribute_tls_model_ie __attribute__ ((tls_model ("initial-exec")))
#endif

/* Pull in things like __attribute_used__ */
#include <sys/cdefs.h>

/* --- this is added to integrate linuxthreads */
#define __USE_UNIX98            1

#ifndef __ASSEMBLER__
# ifdef IS_IN_libc

#  define __need_size_t
#  include <stddef.h>

/* sources are built w/ _GNU_SOURCE, this gets undefined */
extern int __xpg_strerror_r (int __errnum, char *__buf, size_t __buflen);
//extern char *__glibc_strerror_r (int __errnum, char *__buf, size_t __buflen);

/* #include <pthread.h> */
#  ifndef __UCLIBC_HAS_THREADS__
#   define __pthread_mutex_init(mutex, mutexattr)         ((void)0)
#   define __pthread_mutex_lock(mutex)                    ((void)0)
#   define __pthread_mutex_trylock(mutex)                 ((void)0)
#   define __pthread_mutex_unlock(mutex)                  ((void)0)
#  endif

/* internal access to program name */
extern const char *__uclibc_progname attribute_hidden;

# endif /* IS_IN_libc */

/* #include <alloca.h> */
#include <bits/stackinfo.h>
#if _STACK_GROWS_DOWN
# define extend_alloca(buf, len, newlen) \
  (__typeof (buf)) ({ size_t __newlen = (newlen);			      \
		      char *__newbuf = alloca (__newlen);		      \
		      if (__newbuf + __newlen == (char *) buf)		      \
			len += __newlen;				      \
		      else						      \
			len = __newlen;					      \
		      __newbuf; })
#elif _STACK_GROWS_UP
# define extend_alloca(buf, len, newlen) \
  (__typeof (buf)) ({ size_t __newlen = (newlen);			      \
		      char *__newbuf = alloca (__newlen);		      \
		      char *__buf = (buf);				      \
		      if (__buf + __newlen == __newbuf)			      \
			{						      \
			  len += __newlen;				      \
			  __newbuf = __buf;				      \
			}						      \
		      else						      \
			len = __newlen;					      \
		      __newbuf; })
#else
# warning unknown stack
# define extend_alloca(buf, len, newlen) \
  alloca (((len) = (newlen)))
#endif

#endif /* __ASSEMBLER__ */

#endif /* _LIBC_INTERNAL_H */