[v3,09/10] debug: Improve fcntl.h fortify warnings with clang

It improves open, open64, openat, and openat64.  The compile and runtime
checks have similar coverage as with GCC.

Checked on aarch64, armhf, x86_64, and i686.
---
 io/bits/fcntl2.h | 92 ++++++++++++++++++++++++++++++++++++++++++++++++
 io/fcntl.h       |  3 +-
 misc/sys/cdefs.h |  9 ++++-
 3 files changed, 101 insertions(+), 3 deletions(-)

On 2/8/24 13:46, Adhemerval Zanella wrote:
> It improves open, open64, openat, and openat64.  The compile and runtime
> checks have similar coverage as with GCC.
> 

LGTM.

Tested on x86_64 and i686.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

> Checked on aarch64, armhf, x86_64, and i686.
> ---
>  io/bits/fcntl2.h | 92 ++++++++++++++++++++++++++++++++++++++++++++++++
>  io/fcntl.h       |  3 +-
>  misc/sys/cdefs.h |  9 ++++-
>  3 files changed, 101 insertions(+), 3 deletions(-)
> 
> diff --git a/io/bits/fcntl2.h b/io/bits/fcntl2.h
> index 34f05d793d..26f1792fd1 100644
> --- a/io/bits/fcntl2.h
> +++ b/io/bits/fcntl2.h
> @@ -32,6 +32,8 @@ extern int __REDIRECT (__open_2, (const char *__path, int __oflag),
>  extern int __REDIRECT (__open_alias, (const char *__path, int __oflag, ...),
>  		       open64) __nonnull ((1));
>  #endif
> +
> +#ifdef __va_arg_pack_len
>  __errordecl (__open_too_many_args,
>  	     "open can be called either with 2 or 3 arguments, not more");
>  __errordecl (__open_missing_mode,
> @@ -58,12 +60,34 @@ open (const char *__path, int __oflag, ...)
>  
>    return __open_alias (__path, __oflag, __va_arg_pack ());
>  }
> +#elif __fortify_use_clang
> +__fortify_function_error_function __attribute_overloadable__ int
> +open (const char *__path, int __oflag, mode_t __mode, ...)
> +     __fortify_clang_unavailable ("open can be called either with 2 or 3 arguments, not more");
> +
> +__fortify_function __attribute_overloadable__ int
> +open (__fortify_clang_overload_arg (const char *, ,__path), int __oflag)
> +     __fortify_clang_prefer_this_overload
> +     __fortify_clang_error (__OPEN_NEEDS_MODE (__oflag),
> +			    "open with O_CREAT or O_TMPFILE in second argument needs 3 arguments")
> +{
> +  return __open_2 (__path, __oflag);
> +}
> +
> +__fortify_function __attribute_overloadable__ int
> +open (__fortify_clang_overload_arg (const char *, ,__path), int __oflag,
> +      mode_t __mode)
> +{
> +  return __open_alias (__path, __oflag, __mode);
> +}
> +#endif
>  
>  
>  #ifdef __USE_LARGEFILE64
>  extern int __open64_2 (const char *__path, int __oflag) __nonnull ((1));
>  extern int __REDIRECT (__open64_alias, (const char *__path, int __oflag,
>  					...), open64) __nonnull ((1));
> +# ifdef __va_arg_pack_len
>  __errordecl (__open64_too_many_args,
>  	     "open64 can be called either with 2 or 3 arguments, not more");
>  __errordecl (__open64_missing_mode,
> @@ -90,6 +114,27 @@ open64 (const char *__path, int __oflag, ...)
>  
>    return __open64_alias (__path, __oflag, __va_arg_pack ());
>  }
> +# elif __fortify_use_clang
> +__fortify_function_error_function __attribute_overloadable__ int
> +open64 (const char *__path, int __oflag, mode_t __mode, ...)
> +     __fortify_clang_unavailable ("open64 can be called either with 2 or 3 arguments, not more");
> +
> +__fortify_function __attribute_overloadable__ int
> +open64 (__fortify_clang_overload_arg (const char *, ,__path), int __oflag)
> +     __fortify_clang_prefer_this_overload
> +     __fortify_clang_error (__OPEN_NEEDS_MODE (__oflag),
> +			    "open64 with O_CREAT or O_TMPFILE in second argument needs 3 arguments")
> +{
> +  return __open64_2 (__path, __oflag);
> +}
> +
> +__fortify_function __attribute_overloadable__ int
> +open64 (__fortify_clang_overload_arg (const char *, ,__path), int __oflag,
> +	mode_t __mode)
> +{
> +  return __open64_alias (__path, __oflag, __mode);
> +}
> +# endif
>  #endif
>  
>  
> @@ -108,6 +153,8 @@ extern int __REDIRECT (__openat_alias, (int __fd, const char *__path,
>  					int __oflag, ...), openat64)
>       __nonnull ((2));
>  # endif
> +
> +# ifdef __va_arg_pack_len
>  __errordecl (__openat_too_many_args,
>  	     "openat can be called either with 3 or 4 arguments, not more");
>  __errordecl (__openat_missing_mode,
> @@ -134,6 +181,28 @@ openat (int __fd, const char *__path, int __oflag, ...)
>  
>    return __openat_alias (__fd, __path, __oflag, __va_arg_pack ());
>  }
> +# elif __fortify_use_clang
> +__fortify_function_error_function __attribute_overloadable__ int
> +openat (int __fd, const char *__path, int __oflag, mode_t __mode, ...)
> +     __fortify_clang_unavailable ("openat can be called either with 3 or 4 arguments, not more");
> +
> +__fortify_function __attribute_overloadable__ int
> +openat (int __fd, __fortify_clang_overload_arg (const char *, ,__path),
> +	int __oflag)
> +     __fortify_clang_prefer_this_overload
> +     __fortify_clang_error (__OPEN_NEEDS_MODE (__oflag),
> +			    "openat with O_CREAT or O_TMPFILE in third argument needs 4 arguments")
> +{
> +  return __openat_2 (__fd, __path, __oflag);
> +}
> +
> +__fortify_function __attribute_overloadable__ int
> +openat (int __fd, __fortify_clang_overload_arg (const char *, ,__path),
> +	int __oflag, mode_t __mode)
> +{
> +  return __openat_alias (__fd, __path, __oflag, __mode);
> +}
> +# endif
>  
>  
>  # ifdef __USE_LARGEFILE64
> @@ -147,6 +216,7 @@ __errordecl (__openat64_too_many_args,
>  __errordecl (__openat64_missing_mode,
>  	     "openat64 with O_CREAT or O_TMPFILE in third argument needs 4 arguments");
>  
> +#  ifdef __va_arg_pack_len
>  __fortify_function int
>  openat64 (int __fd, const char *__path, int __oflag, ...)
>  {
> @@ -168,5 +238,27 @@ openat64 (int __fd, const char *__path, int __oflag, ...)
>  
>    return __openat64_alias (__fd, __path, __oflag, __va_arg_pack ());
>  }
> +# elif __fortify_use_clang
> +__fortify_function_error_function __attribute_overloadable__ int
> +openat64 (int __fd, const char *__path, int __oflag, mode_t __mode, ...)
> +     __fortify_clang_unavailable ("openat64 can be called either with 3 or 4 arguments, not more");
> +
> +__fortify_function __attribute_overloadable__ int
> +openat64 (int __fd, __fortify_clang_overload_arg (const char *, ,__path),
> +	  int __oflag)
> +     __fortify_clang_prefer_this_overload
> +     __fortify_clang_error (__OPEN_NEEDS_MODE (__oflag),
> +			    "openat64 with O_CREAT or O_TMPFILE in third argument needs 4 arguments")
> +{
> +  return __openat64_2 (__fd, __path, __oflag);
> +}
> +
> +__fortify_function __attribute_overloadable__ int
> +openat64 (int __fd, __fortify_clang_overload_arg (const char *, ,__path),
> +	  int __oflag, mode_t __mode)
> +{
> +  return __openat64_alias (__fd, __path, __oflag, __mode);
> +}
> +#  endif
>  # endif
>  #endif
> diff --git a/io/fcntl.h b/io/fcntl.h
> index 9cee0b5900..38aa12d7f2 100644
> --- a/io/fcntl.h
> +++ b/io/fcntl.h
> @@ -337,8 +337,7 @@ extern int posix_fallocate64 (int __fd, off64_t __offset, off64_t __len);
>  
>  
>  /* Define some inlines helping to catch common problems.  */
> -#if __USE_FORTIFY_LEVEL > 0 && defined __fortify_function \
> -    && defined __va_arg_pack_len
> +#if __USE_FORTIFY_LEVEL > 0 && defined __fortify_function
>  # include <bits/fcntl2.h>
>  #endif
>  
> diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
> index 62507044c8..6b03417453 100644
> --- a/misc/sys/cdefs.h
> +++ b/misc/sys/cdefs.h
> @@ -257,7 +257,9 @@
>  
>  # define __fortify_clang_warning(__c, __msg) \
>    __attribute__ ((__diagnose_if__ ((__c), (__msg), "warning")))
> -# define __fortify_clang_warning_only_if_bos0_lt(n, buf, complaint) \
> +#  define __fortify_clang_error(__c, __msg) \
> +  __attribute__ ((__diagnose_if__ ((__c), (__msg), "error")))
> +#  define __fortify_clang_warning_only_if_bos0_lt(n, buf, complaint) \
>    __attribute__ ((__diagnose_if__ \
>  		  (__fortify_clang_bosn_args (__bos0, n, buf, 1, complaint))))
>  # define __fortify_clang_warning_only_if_bos0_lt2(n, buf, div, complaint) \
> @@ -270,6 +272,11 @@
>    __attribute__ ((__diagnose_if__ \
>  		  (__fortify_clang_bosn_args (__bos, n, buf, div, complaint))))
>  
> +#  define __fortify_clang_prefer_this_overload \
> +  __attribute__ ((enable_if (1, "")))

OK. Use enable_if.

> +#  define __fortify_clang_unavailable(__msg) \
> +  __attribute__ ((unavailable(__msg)))
> +
>  # if __USE_FORTIFY_LEVEL == 3
>  #  define __fortify_clang_overload_arg(__type, __attr, __name) \
>    __type __attr const __fortify_clang_pass_dynamic_object_size __name