Apply asm redirections in stdio.h before first use [BZ #27087]

  Compilers may not be able to apply asm redirections to functions after
these functions are used for the first time, e.g. clang 13.
Fix [BZ #27087] by applying all long double-related asm redirections
before using functions in bits/stdio.h.
However, as these asm redirections depend on the declarations provided
by libio/bits/stdio2.h, this header was split in 2:

 - libio/bits/stdio2-dec.h contains all function declarations;
 - libio/bits/stdio2.h remains with the remaining contents, including
   redirections.
---
 include/bits/stdio2-dec.h |   1 +
 libio/Makefile            |   2 +-
 libio/bits/stdio2-dec.h   | 110 ++++++++++++++++++++++++++++++++++++++
 libio/bits/stdio2.h       |  62 ---------------------
 libio/stdio.h             |  18 +++++--
 5 files changed, 125 insertions(+), 68 deletions(-)
 create mode 100644 include/bits/stdio2-dec.h
 create mode 100644 libio/bits/stdio2-dec.h
  

On 12/15/21 1:23 PM, Tulio Magno Quites Machado Filho via Libc-alpha wrote:
> Compilers may not be able to apply asm redirections to functions after
> these functions are used for the first time, e.g. clang 13.
> Fix [BZ #27087] by applying all long double-related asm redirections
> before using functions in bits/stdio.h.
> However, as these asm redirections depend on the declarations provided
> by libio/bits/stdio2.h, this header was split in 2:
> 
>   - libio/bits/stdio2-dec.h contains all function declarations;
>   - libio/bits/stdio2.h remains with the remaining contents, including
>     redirections.
> ---
>   include/bits/stdio2-dec.h |   1 +
>   libio/Makefile            |   2 +-
>   libio/bits/stdio2-dec.h   | 110 ++++++++++++++++++++++++++++++++++++++
>   libio/bits/stdio2.h       |  62 ---------------------
>   libio/stdio.h             |  18 +++++--
>   5 files changed, 125 insertions(+), 68 deletions(-)
>   create mode 100644 include/bits/stdio2-dec.h
>   create mode 100644 libio/bits/stdio2-dec.h
> 
> diff --git a/include/bits/stdio2-dec.h b/include/bits/stdio2-dec.h
> new file mode 100644
> index 0000000000..4d74e4bf82
> --- /dev/null
> +++ b/include/bits/stdio2-dec.h
> @@ -0,0 +1 @@
> +#include <libio/bits/stdio2-dec.h>
> diff --git a/libio/Makefile b/libio/Makefile
> index 5336b7d595..19e2143d11 100644
> --- a/libio/Makefile
> +++ b/libio/Makefile
> @@ -23,7 +23,7 @@ subdir	:= libio
>   include ../Makeconfig
> 
>   headers	:= stdio.h \
> -	   bits/stdio.h bits/stdio2.h bits/stdio-ldbl.h \
> +	   bits/stdio.h bits/stdio2.h bits/stdio2-dec.h bits/stdio-ldbl.h \
>   	   bits/types/FILE.h bits/types/__FILE.h bits/types/struct_FILE.h \
>   	   bits/types/__fpos_t.h bits/types/__fpos64_t.h \
>   	   bits/types/cookie_io_functions_t.h
> diff --git a/libio/bits/stdio2-dec.h b/libio/bits/stdio2-dec.h
> new file mode 100644
> index 0000000000..80ab10bccf
> --- /dev/null
> +++ b/libio/bits/stdio2-dec.h
> @@ -0,0 +1,110 @@
> +/* Checking macros for stdio functions. Declarations only.
> +   Copyright (C) 2004-2021 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 _BITS_STDIO2_DEC_H
> +#define _BITS_STDIO2_DEC_H 1
> +
> +#ifndef _STDIO_H
> +# error "Never include <bits/stdio2-dec.h> directly; use <stdio.h> instead."
> +#endif
> +
> +extern int __sprintf_chk (char *__restrict __s, int __flag, size_t __slen,
> +			  const char *__restrict __format, ...) __THROW
> +    __attr_access ((__write_only__, 1, 3));
> +extern int __vsprintf_chk (char *__restrict __s, int __flag, size_t __slen,
> +			   const char *__restrict __format,
> +			   __gnuc_va_list __ap) __THROW
> +    __attr_access ((__write_only__, 1, 3));OK.

> +
> +#if defined __USE_ISOC99 || defined __USE_UNIX98
> +
> +extern int __snprintf_chk (char *__restrict __s, size_t __n, int __flag,
> +			   size_t __slen, const char *__restrict __format,
> +			   ...) __THROW
> +    __attr_access ((__write_only__, 1, 2));
> +extern int __vsnprintf_chk (char *__restrict __s, size_t __n, int __flag,
> +			    size_t __slen, const char *__restrict __format,
> +			    __gnuc_va_list __ap) __THROW;
> +
> +#endif
> +
OK.


> +#if __USE_FORTIFY_LEVEL > 1
> +
> +extern int __fprintf_chk (FILE *__restrict __stream, int __flag,
> +			  const char *__restrict __format, ...);
> +extern int __printf_chk (int __flag, const char *__restrict __format, ...);
> +extern int __vfprintf_chk (FILE *__restrict __stream, int __flag,
> +			   const char *__restrict __format, __gnuc_va_list __ap);
> +extern int __vprintf_chk (int __flag, const char *__restrict __format,
> +			  __gnuc_va_list __ap);
> +
> +# ifdef __USE_XOPEN2K8
> +extern int __dprintf_chk (int __fd, int __flag, const char *__restrict __fmt,
> +			  ...) __attribute__ ((__format__ (__printf__, 3, 4)));
> +extern int __vdprintf_chk (int __fd, int __flag,
> +			   const char *__restrict __fmt, __gnuc_va_list __arg)
> +     __attribute__ ((__format__ (__printf__, 3, 0)));
> +# endif
> +
> +# ifdef __USE_GNU
> +
> +extern int __asprintf_chk (char **__restrict __ptr, int __flag,
> +			   const char *__restrict __fmt, ...)
> +     __THROW __attribute__ ((__format__ (__printf__, 3, 4))) __wur;
> +extern int __vasprintf_chk (char **__restrict __ptr, int __flag,
> +			    const char *__restrict __fmt, __gnuc_va_list __arg)
> +     __THROW __attribute__ ((__format__ (__printf__, 3, 0))) __wur;
> +extern int __obstack_printf_chk (struct obstack *__restrict __obstack,
> +				 int __flag, const char *__restrict __format,
> +				 ...)
> +     __THROW __attribute__ ((__format__ (__printf__, 3, 4)));
> +extern int __obstack_vprintf_chk (struct obstack *__restrict __obstack,
> +				  int __flag,
> +				  const char *__restrict __format,
> +				  __gnuc_va_list __args)
> +     __THROW __attribute__ ((__format__ (__printf__, 3, 0)));
> +
> +# endif
> +#endif
OK.

> +
> +#if __GLIBC_USE (DEPRECATED_GETS)
> +extern char *__gets_chk (char *__str, size_t) __wur;
> +#endif
OK.

> +
> +extern char *__fgets_chk (char *__restrict __s, size_t __size, int __n,
> +			  FILE *__restrict __stream)
> +    __wur __attr_access ((__write_only__, 1, 3));
> +
OK.

> +extern size_t __fread_chk (void *__restrict __ptr, size_t __ptrlen,
> +			   size_t __size, size_t __n,
> +			   FILE *__restrict __stream) __wur;
> +
OK.

> +#ifdef __USE_GNU
> +extern char *__fgets_unlocked_chk (char *__restrict __s, size_t __size,
> +				   int __n, FILE *__restrict __stream)
> +    __wur __attr_access ((__write_only__, 1, 3));
> +#endif
OK.

> +
> +#ifdef __USE_MISC
> +# undef fread_unlocked
> +extern size_t __fread_unlocked_chk (void *__restrict __ptr, size_t __ptrlen,
> +				    size_t __size, size_t __n,
> +				    FILE *__restrict __stream) __wur;
> +#endif
> +
> +#endif /* bits/stdio2-dec.h.  */
OK.


> diff --git a/libio/bits/stdio2.h b/libio/bits/stdio2.h
> index 40ff16b01b..4570f86a44 100644
> --- a/libio/bits/stdio2.h
> +++ b/libio/bits/stdio2.h
> @@ -23,14 +23,6 @@
>   # error "Never include <bits/stdio2.h> directly; use <stdio.h> instead."
>   #endif
> 
> -extern int __sprintf_chk (char *__restrict __s, int __flag, size_t __slen,
> -			  const char *__restrict __format, ...) __THROW
> -    __attr_access ((__write_only__, 1, 3));
> -extern int __vsprintf_chk (char *__restrict __s, int __flag, size_t __slen,
> -			   const char *__restrict __format,
> -			   __gnuc_va_list __ap) __THROW
> -    __attr_access ((__write_only__, 1, 3));
> -

OK.


>   #ifdef __va_arg_pack
>   __fortify_function int
>   __NTH (sprintf (char *__restrict __s, const char *__restrict __fmt, ...))
> @@ -54,15 +46,6 @@ __NTH (vsprintf (char *__restrict __s, const char *__restrict __fmt,
>   }
> 
>   #if defined __USE_ISOC99 || defined __USE_UNIX98
> -
> -extern int __snprintf_chk (char *__restrict __s, size_t __n, int __flag,
> -			   size_t __slen, const char *__restrict __format,
> -			   ...) __THROW
> -    __attr_access ((__write_only__, 1, 2));
> -extern int __vsnprintf_chk (char *__restrict __s, size_t __n, int __flag,
> -			    size_t __slen, const char *__restrict __format,
> -			    __gnuc_va_list __ap) __THROW;
> -
OK.

>   # ifdef __va_arg_pack
>   __fortify_function int
>   __NTH (snprintf (char *__restrict __s, size_t __n,
> @@ -89,15 +72,6 @@ __NTH (vsnprintf (char *__restrict __s, size_t __n,
>   #endif
> 
>   #if __USE_FORTIFY_LEVEL > 1
> -
> -extern int __fprintf_chk (FILE *__restrict __stream, int __flag,
> -			  const char *__restrict __format, ...);
> -extern int __printf_chk (int __flag, const char *__restrict __format, ...);
> -extern int __vfprintf_chk (FILE *__restrict __stream, int __flag,
> -			   const char *__restrict __format, __gnuc_va_list __ap);
> -extern int __vprintf_chk (int __flag, const char *__restrict __format,
> -			  __gnuc_va_list __ap);
> -OK.


>   # ifdef __va_arg_pack
>   __fortify_function int
>   fprintf (FILE *__restrict __stream, const char *__restrict __fmt, ...)
> @@ -136,12 +110,6 @@ vfprintf (FILE *__restrict __stream,
>   }
> 
>   # ifdef __USE_XOPEN2K8
> -extern int __dprintf_chk (int __fd, int __flag, const char *__restrict __fmt,
> -			  ...) __attribute__ ((__format__ (__printf__, 3, 4)));
> -extern int __vdprintf_chk (int __fd, int __flag,
> -			   const char *__restrict __fmt, __gnuc_va_list __arg)
> -     __attribute__ ((__format__ (__printf__, 3, 0)));
> -
OK.

>   #  ifdef __va_arg_pack
>   __fortify_function int
>   dprintf (int __fd, const char *__restrict __fmt, ...)
> @@ -162,23 +130,6 @@ vdprintf (int __fd, const char *__restrict __fmt, __gnuc_va_list __ap)
>   # endif
> 
>   # ifdef __USE_GNU
> -
> -extern int __asprintf_chk (char **__restrict __ptr, int __flag,
> -			   const char *__restrict __fmt, ...)
> -     __THROW __attribute__ ((__format__ (__printf__, 3, 4))) __wur;
> -extern int __vasprintf_chk (char **__restrict __ptr, int __flag,
> -			    const char *__restrict __fmt, __gnuc_va_list __arg)
> -     __THROW __attribute__ ((__format__ (__printf__, 3, 0))) __wur;
> -extern int __obstack_printf_chk (struct obstack *__restrict __obstack,
> -				 int __flag, const char *__restrict __format,
> -				 ...)
> -     __THROW __attribute__ ((__format__ (__printf__, 3, 4)));
> -extern int __obstack_vprintf_chk (struct obstack *__restrict __obstack,
> -				  int __flag,
> -				  const char *__restrict __format,
> -				  __gnuc_va_list __args)
> -     __THROW __attribute__ ((__format__ (__printf__, 3, 0)));
> -
OK.

>   #  ifdef __va_arg_pack
>   __fortify_function int
>   __NTH (asprintf (char **__restrict __ptr, const char *__restrict __fmt, ...))
> @@ -231,7 +182,6 @@ __NTH (obstack_vprintf (struct obstack *__restrict __obstack,
>   #endif
> 
>   #if __GLIBC_USE (DEPRECATED_GETS)
> -extern char *__gets_chk (char *__str, size_t) __wur;
OK.

>   extern char *__REDIRECT (__gets_warn, (char *__str), gets)
>        __wur __warnattr ("please use fgets or getline instead, gets can't "
>   		       "specify buffer size");
> @@ -245,9 +195,6 @@ gets (char *__str)
>   }
>   #endif
> 
> -extern char *__fgets_chk (char *__restrict __s, size_t __size, int __n,
> -			  FILE *__restrict __stream)
> -    __wur __attr_access ((__write_only__, 1, 3));
OK.

>   extern char *__REDIRECT (__fgets_alias,
>   			 (char *__restrict __s, int __n,
>   			  FILE *__restrict __stream), fgets)
> @@ -269,9 +216,6 @@ fgets (char *__restrict __s, int __n, FILE *__restrict __stream)
>     return __fgets_chk (__s, sz, __n, __stream);
>   }
> 
> -extern size_t __fread_chk (void *__restrict __ptr, size_t __ptrlen,
> -			   size_t __size, size_t __n,
> -			   FILE *__restrict __stream) __wur;
OK.

>   extern size_t __REDIRECT (__fread_alias,
>   			  (void *__restrict __ptr, size_t __size,
>   			   size_t __n, FILE *__restrict __stream),
> @@ -297,9 +241,6 @@ fread (void *__restrict __ptr, size_t __size, size_t __n,
>   }
> 
>   #ifdef __USE_GNU
> -extern char *__fgets_unlocked_chk (char *__restrict __s, size_t __size,
> -				   int __n, FILE *__restrict __stream)
> -    __wur __attr_access ((__write_only__, 1, 3));
OK.

>   extern char *__REDIRECT (__fgets_unlocked_alias,
>   			 (char *__restrict __s, int __n,
>   			  FILE *__restrict __stream), fgets_unlocked)
> @@ -324,9 +265,6 @@ fgets_unlocked (char *__restrict __s, int __n, FILE *__restrict __stream)
> 
>   #ifdef __USE_MISC
>   # undef fread_unlocked
> -extern size_t __fread_unlocked_chk (void *__restrict __ptr, size_t __ptrlen,
> -				    size_t __size, size_t __n,
> -				    FILE *__restrict __stream) __wur;
OK.

>   extern size_t __REDIRECT (__fread_unlocked_alias,
>   			  (void *__restrict __ptr, size_t __size,
>   			   size_t __n, FILE *__restrict __stream),
> diff --git a/libio/stdio.h b/libio/stdio.h
> index f208f5ef79..da763c9f1b 100644
> --- a/libio/stdio.h
> +++ b/libio/stdio.h
> @@ -885,20 +885,28 @@ extern void funlockfile (FILE *__stream) __THROW;
>   extern int __uflow (FILE *);
>   extern int __overflow (FILE *, int);
> 
> +#if __USE_FORTIFY_LEVEL > 0 && defined __fortify_function
> +/* Declare all functions from bits/stdio2-dec.h first.  */
> +# include <bits/stdio2-dec.h>
> +#endif
> +
> +/* The following headers provide asm redirections.  These redirections must
> +   appear before the first usage of these functions, e.g. in bits/stdio.h.  */
> +#include <bits/floatn.h>
OK. I think you are just moving the existing code, but is this include 
redundant? It seems to happen a bit earlier around line 430.

> +#if defined __LDBL_COMPAT || __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
> +# include <bits/stdio-ldbl.h>
> +#endif
> +
>   /* If we are compiling with optimizing read this file.  It contains
>      several optimizing inline functions and macros.  */
>   #ifdef __USE_EXTERN_INLINES
>   # include <bits/stdio.h>
>   #endif
>   #if __USE_FORTIFY_LEVEL > 0 && defined __fortify_function
> +/* Now include the function definitions and redirects too.  */
>   # include <bits/stdio2.h>
>   #endif
> 
> -#include <bits/floatn.h>
> -#if defined __LDBL_COMPAT || __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
> -# include <bits/stdio-ldbl.h>
> -#endif
> -
OK.

>   __END_DECLS
> 
>   #endif /* <stdio.h> included.  */
>

One minor question about the new file name, is "dec" meant to read as 
"declaration"?

This LGTM provided it passes build-many-glibc.py.