Re: stdio_ext.h function implementations

[Yaakov Selkowitz <yselkowi at redhat dot com>]

On 2014-12-10 03:40, Corinna Vinschen wrote:
> On Dec  9 14:58, Yaakov Selkowitz wrote:
> > Currently, the bulk of the <stdio_ext.h> functions[1][2] are implemented as
> > inline code, or macros on non-gcc-compatible toolchains.  However, there are
> > a few issues with that:
> >
> > * Header-only implementations result in false negatives from AC_CHECK_FUNC
> > tests and the like.  For instance, cpio FTBFS on Cygwin currently because it
> > tries to implement a replacement for a "missing" __fpending which conflicts
> > with the one already in <stdio_ext.h>.
> >
> > * Macro implementations of libc functions need to be undef'ed and backed by
> > real functions with C++ (otherwise you get syntax errors in the ::func
> > form).  Are the inline implementations used by GCC safe for these purposes?
>
> Apart from the fact that the header was broken (too many "inline", fixed
> now), inline functions are safe.  ::__fpending(stdin) is a valid expression.
>
> > * No documentation is generated for these functions.

Patch attached; it also fixes the spelling of __fwritable() to match 
Solaris and glibc.

Note that this code will only be pulled in by (1) AC_CHECK_FUNC 
configure tests or the like, (2) a non-__GNUC__-defining C++ compiler 
(IOW *not* g++, clang++, or icpc, nor *any* _C_ compiler), or (3) 
dlopen()ing these functions from a shared libc (e.g. Cygwin).  In all 
other cases, the inlines/macros in <stdio_ext.h> will be used. 
Therefore, I see little loss in providing a single .c file for these.

These are #ifndef __rtems__ because they have chosen not to support 
<stdio_ext.h> at all.

The functions call _newlib_flockfile_{start,end} even though the macros 
do not, to match the behaviour of clearerr() and feof().

--
Yaakov Selkowitz
Associate Software Engineer, ARM
Red Hat, Inc.

2014-12-10  Yaakov Selkowitz  <yselkowi@...>

	* libc/include/stdio_ext.h: Rename __fwriteable to __fwritable,
	leaving a macro for compatibility.
	[!__GNUC__]: Declare real functions for the macros, and make
	the macros conditional on !__cplusplus.
	* libc/stdio/Makefile.am: Add new stdio_ext.c file.
	* libc/stdio/Makefile.in: Regenerate.
	* libc/stdio/stdio.tex: Include stdio_ext.def.
	* libc/stdio/stdio_ext.c: New file.

Index: libc/include/stdio_ext.h
===================================================================
RCS file: /cvs/src/src/newlib/libc/include/stdio_ext.h,v
retrieving revision 1.3
diff -u -p -r1.3 stdio_ext.h
--- libc/include/stdio_ext.h	10 Dec 2014 09:39:06 -0000	1.3
+++ libc/include/stdio_ext.h	11 Dec 2014 04:33:51 -0000
@@ -23,6 +23,9 @@ void	 _EXFUN(__fpurge,(FILE *));
    int __fsetlocking (FILE *__fp, int __type);
 */
 
+/* this function was previously misspelled */
+#define __fwriteable(__fp) __fwritable(__fp)
+
 #ifdef  __GNUC__
 
 _ELIDABLE_INLINE size_t
@@ -38,7 +41,7 @@ _ELIDABLE_INLINE int
 __freadable (FILE *__fp) { return (__fp->_flags & (__SRD | __SRW)) != 0; }
 
 _ELIDABLE_INLINE int
-__fwriteable (FILE *__fp) { return (__fp->_flags & (__SWR | __SRW)) != 0; }
+__fwritable (FILE *__fp) { return (__fp->_flags & (__SWR | __SRW)) != 0; }
 
 _ELIDABLE_INLINE int
 __flbf (FILE *__fp) { return (__fp->_flags & __SLBF) != 0; }
@@ -48,14 +51,26 @@ __fpending (FILE *__fp) { return __fp->_
 
 #else
 
+size_t	 _EXFUN(__fbufsize,(FILE *));
+int	 _EXFUN(__freading,(FILE *));
+int	 _EXFUN(__fwriting,(FILE *));
+int	 _EXFUN(__freadable,(FILE *));
+int	 _EXFUN(__fwritable,(FILE *));
+int	 _EXFUN(__flbf,(FILE *));
+size_t	 _EXFUN(__fpending,(FILE *));
+
+#ifndef __cplusplus
+
 #define __fbufsize(__fp) ((size_t) (__fp)->_bf._size)
 #define __freading(__fp) (((__fp)->_flags & __SRD) != 0)
 #define __fwriting(__fp) (((__fp)->_flags & __SWR) != 0)
 #define __freadable(__fp) (((__fp)->_flags & (__SRD | __SRW)) != 0)
-#define __fwriteable(__fp) (((__fp)->_flags & (__SWR | __SRW)) != 0)
+#define __fwritable(__fp) (((__fp)->_flags & (__SWR | __SRW)) != 0)
 #define __flbf(__fp) (((__fp)->_flags & __SLBF) != 0)
 #define __fpending(__fp) ((size_t) ((__fp)->_p - (__fp)->_bf._base))
 
+#endif /* __cplusplus */
+
 #endif /* __GNUC__ */
 
 _END_STD_C
Index: libc/stdio/Makefile.am
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/Makefile.am,v
retrieving revision 1.35
diff -u -p -r1.35 Makefile.am
--- libc/stdio/Makefile.am	4 Jul 2014 17:21:42 -0000	1.35
+++ libc/stdio/Makefile.am	11 Dec 2014 04:33:52 -0000
@@ -155,6 +155,7 @@ ELIX_4_SOURCES = \
 	open_memstream.c	\
 	putwc.c			\
 	putwchar.c		\
+	stdio_ext.c		\
 	swprintf.c		\
 	swscanf.c		\
 	ungetwc.c		\
@@ -391,6 +392,7 @@ CHEWOUT_FILES = \
 	setvbuf.def		\
 	sprintf.def		\
 	sscanf.def		\
+	stdio_ext.def		\
 	swprintf.def		\
 	swscanf.def		\
 	tmpfile.def		\
@@ -457,6 +459,7 @@ $(lpfx)sniprintf.$(oext): local.h
 $(lpfx)sprintf.$(oext): local.h
 $(lpfx)sscanf.$(oext): local.h
 $(lpfx)stdio.$(oext): local.h
+$(lpfx)stdio_ext.$(oext): local.h
 if NEWLIB_NANO_FORMATTED_IO
 $(lpfx)nano-svfprintf.$(oext): local.h nano-vfprintf_local.h
 $(lpfx)nano-svfscanf.$(oext): local.h nano-vfscanf_local.h
Index: libc/stdio/Makefile.in
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/Makefile.in,v
retrieving revision 1.56
diff -u -p -r1.56 Makefile.in
--- libc/stdio/Makefile.in	4 Jul 2014 17:21:42 -0000	1.56
+++ libc/stdio/Makefile.in	11 Dec 2014 04:33:53 -0000
@@ -152,6 +152,7 @@ am__objects_2 = $(am__objects_1) lib_a-c
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	lib_a-open_memstream.$(OBJEXT) \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	lib_a-putwc.$(OBJEXT) \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	lib_a-putwchar.$(OBJEXT) \
+@ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	lib_a-stdio_ext.$(OBJEXT) \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	lib_a-swprintf.$(OBJEXT) \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	lib_a-swscanf.$(OBJEXT) \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	lib_a-ungetwc.$(OBJEXT) \
@@ -214,6 +215,7 @@ am__objects_8 = $(am__objects_7) clearer
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	open_memstream.lo \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	putwc.lo \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	putwchar.lo \
+@ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	stdio_ext.lo \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	swprintf.lo \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	swscanf.lo \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	ungetwc.lo \
@@ -521,6 +523,7 @@ GENERAL_SOURCES = \
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	open_memstream.c	\
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	putwc.c			\
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	putwchar.c		\
+@ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	stdio_ext.c		\
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	swprintf.c		\
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	swscanf.c		\
 @ELIX_LEVEL_1_FALSE@@ELIX_LEVEL_2_FALSE@@ELIX_LEVEL_3_FALSE@	ungetwc.c		\
@@ -663,6 +666,7 @@ CHEWOUT_FILES = \
 	setvbuf.def		\
 	sprintf.def		\
 	sscanf.def		\
+	stdio_ext.def		\
 	swprintf.def		\
 	swscanf.def		\
 	tmpfile.def		\
@@ -1405,6 +1409,12 @@ lib_a-putwchar.o: putwchar.c
 lib_a-putwchar.obj: putwchar.c
 	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-putwchar.obj `if test -f 'putwchar.c'; then $(CYGPATH_W) 'putwchar.c'; else $(CYGPATH_W) '$(srcdir)/putwchar.c'; fi`
 
+lib_a-stdio_ext.o: stdio_ext.c
+	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-stdio_ext.o `test -f 'stdio_ext.c' || echo '$(srcdir)/'`stdio_ext.c
+
+lib_a-stdio_ext.obj: stdio_ext.c
+	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-stdio_ext.obj `if test -f 'stdio_ext.c'; then $(CYGPATH_W) 'stdio_ext.c'; else $(CYGPATH_W) '$(srcdir)/stdio_ext.c'; fi`
+
 lib_a-swprintf.o: swprintf.c
 	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-swprintf.o `test -f 'swprintf.c' || echo '$(srcdir)/'`swprintf.c
 
@@ -1788,6 +1798,7 @@ $(lpfx)sniprintf.$(oext): local.h
 $(lpfx)sprintf.$(oext): local.h
 $(lpfx)sscanf.$(oext): local.h
 $(lpfx)stdio.$(oext): local.h
+$(lpfx)stdio_ext.$(oext): local.h
 @NEWLIB_NANO_FORMATTED_IO_TRUE@$(lpfx)nano-svfprintf.$(oext): local.h nano-vfprintf_local.h
 @NEWLIB_NANO_FORMATTED_IO_TRUE@$(lpfx)nano-svfscanf.$(oext): local.h nano-vfscanf_local.h
 $(lpfx)svfiprintf.$(oext): local.h
Index: libc/stdio/stdio.tex
===================================================================
RCS file: /cvs/src/src/newlib/libc/stdio/stdio.tex,v
retrieving revision 1.15
diff -u -p -r1.15 stdio.tex
--- libc/stdio/stdio.tex	3 Jul 2009 11:58:04 -0000	1.15
+++ libc/stdio/stdio.tex	11 Dec 2014 04:33:53 -0000
@@ -283,6 +283,9 @@ structure.
 @include stdio/sscanf.def
 
 @page
+@include stdio/stdio_ext.def
+
+@page
 @include stdio/swprintf.def
 
 @page
Index: libc/stdio/stdio_ext.c
===================================================================
RCS file: libc/stdio/stdio_ext.c
diff -N libc/stdio/stdio_ext.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ libc/stdio/stdio_ext.c	11 Dec 2014 04:33:53 -0000
@@ -0,0 +1,149 @@
+/*
+FUNCTION
+<<__fbufsize>>, <<__fpending>>, <<__flbf>>, <<__freadable>>, <<__fwritable>> <<__freading>>, <<__fwriting>>,---access internals of FILE structure
+
+INDEX
+	__fbufsize
+INDEX
+	__fpending
+INDEX
+	__flbf
+INDEX
+	__freadable
+INDEX
+	__fwritable
+INDEX
+	__freading
+INDEX
+	__fwriting
+
+ANSI_SYNOPSIS
+	#include <stdio.h>
+	#include <stdio_ext.h>
+	size_t __fbufsize(FILE *<[fp]>);
+	size_t __fpending(FILE *<[fp]>);
+	int __flbf(FILE *<[fp]>);
+	int __freadable(FILE *<[fp]>);
+	int __fwritable(FILE *<[fp]>);
+	int __freading(FILE *<[fp]>);
+	int __fwriting(FILE *<[fp]>);
+
+DESCRIPTION
+These functions provides access to the internals of the FILE structure <[fp]>.
+
+RETURNS
+<<__fbufsize>> returns the number of bytes in the buffer of stream <[fp]>.
+
+<<__fpending>> returns the number of bytes in the output buffer of stream <[fp]>.
+
+<<__flbf>> returns nonzero if stream <[fp]> is line-buffered, and <<0>> if not.
+
+<<__freadable>> returns nonzero if stream <[fp]> may be read, and <<0>> if not.
+
+<<__fwritable>> returns nonzero if stream <[fp]> may be written, and <<0>> if not.
+
+<<__freading>> returns nonzero if stream <[fp]> if the last operation on
+it was a read, or if it read-only, and <<0>> if not.
+
+<<__fwriting>> returns nonzero if stream <[fp]> if the last operation on
+it was a write, or if it write-only, and <<0>> if not.
+
+PORTABILITY
+These functions originate from Solaris and are also provided by GNU libc.
+
+No supporting OS subroutines are required.
+*/
+
+#ifndef __rtems__
+
+#include <_ansi.h>
+#include <stdio.h>
+#include "local.h"
+
+/* Subroutine versions of the inline or macro functions. */
+
+size_t
+_DEFUN(__fbufsize, (fp),
+       FILE * fp)
+{
+  size_t result;
+  CHECK_INIT(_REENT, fp);
+  _newlib_flockfile_start (fp);
+  result = (size_t) fp->_bf._size;
+  _newlib_flockfile_end (fp);
+  return result;
+}
+
+size_t
+_DEFUN(__fpending, (fp),
+       FILE * fp)
+{
+  size_t result;
+  CHECK_INIT(_REENT, fp);
+  _newlib_flockfile_start (fp);
+  result = fp->_p - fp->_bf._base;
+  _newlib_flockfile_end (fp);
+  return result;
+}
+
+int
+_DEFUN(__flbf, (fp),
+       FILE * fp)
+{
+  int result;
+  CHECK_INIT(_REENT, fp);
+  _newlib_flockfile_start (fp);
+  result = ((fp->_flags & __SLBF) != 0);
+  _newlib_flockfile_end (fp);
+  return result;
+}
+
+int
+_DEFUN(__freadable, (fp),
+       FILE * fp)
+{
+  int result;
+  CHECK_INIT(_REENT, fp);
+  _newlib_flockfile_start (fp);
+  result = ((fp->_flags & (__SRD | __SRW)) != 0);
+  _newlib_flockfile_end (fp);
+  return result;
+}
+
+int
+_DEFUN(__fwritable, (fp),
+       FILE * fp)
+{
+  int result;
+  CHECK_INIT(_REENT, fp);
+  _newlib_flockfile_start (fp);
+  result = ((fp->_flags & (__SWR | __SRW)) != 0);
+  _newlib_flockfile_end (fp);
+  return result;
+}
+
+int
+_DEFUN(__freading, (fp),
+       FILE * fp)
+{
+  int result;
+  CHECK_INIT(_REENT, fp);
+  _newlib_flockfile_start (fp);
+  result = ((fp->_flags & __SRD) != 0);
+  _newlib_flockfile_end (fp);
+  return result;
+}
+
+int
+_DEFUN(__fwriting, (fp),
+       FILE * fp)
+{
+  int result;
+  CHECK_INIT(_REENT, fp);
+  _newlib_flockfile_start (fp);
+  result = ((fp->_flags & __SWR) != 0);
+  _newlib_flockfile_end (fp);
+  return result;
+}
+
+#endif /* __rtems__ */