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-decl.h contains all function declarations;
 - libio/bits/stdio2.h remains with the remaining contents, including
   redirections.

This also adds the access attribute to __vsnprintf_chk that was missing.

Tested with build-many-glibcs.py.

Reviewed-by: Paul E. Murphy <murphyp@linux.ibm.com>

4 files changed, 124 insertions, 68 deletions

diff --git a/libio/Makefile b/libio/Makefile
index e97387743f..3a02611020 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-decl.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-decl.h b/libio/bits/stdio2-decl.h
new file mode 100644
index 0000000000..e398f7182b
--- /dev/null
+++ b/libio/bits/stdio2-decl.h
@@ -0,0 +1,111 @@
+/* Checking macros for stdio functions. Declarations only.
+   Copyright (C) 2004-2022 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 _BITS_STDIO2_DEC_H
+#define _BITS_STDIO2_DEC_H 1
+
+#ifndef _STDIO_H
+# error "Never include <bits/stdio2-decl.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));
+
+#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
+    __attr_access ((__write_only__, 1, 2));
+
+#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);
+
+# 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
+
+#if __GLIBC_USE (DEPRECATED_GETS)
+extern char *__gets_chk (char *__str, size_t) __wur;
+#endif
+
+extern char *__fgets_chk (char *__restrict __s, size_t __size, int __n,
+			  FILE *__restrict __stream)
+    __wur __attr_access ((__write_only__, 1, 3));
+
+extern size_t __fread_chk (void *__restrict __ptr, size_t __ptrlen,
+			   size_t __size, size_t __n,
+			   FILE *__restrict __stream) __wur;
+
+#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
+
+#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-decl.h.  */
diff --git a/libio/bits/stdio2.h b/libio/bits/stdio2.h
index b0b655ee7a..b1e200e716 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));
-
 #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;
-
 # 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);
-
 # 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)));
-
 #  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)));
-
 #  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;
 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));
 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;
 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));
 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;
 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 e6425341ce..0e0f16b464 100644
--- a/libio/stdio.h
+++ b/libio/stdio.h
@@ -885,20 +885,27 @@ 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-decl.h first.  */
+# include <bits/stdio2-decl.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.  */
+#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
-
 __END_DECLS
 
 #endif /* <stdio.h> included.  */