Implement BSD/GNU unlocked stdio extensions.

* libc/include/stdio.h (clearerr_unlocked, feof_unlocked,
ferror_unlocked, fflush_unlocked, fgetc_unlocked, fgets_unlocked,
fileno_unlocked, fputc_unlocked, fputs_unlocked, fread_unlocked,
fwrite_unlocked): Declare.
* libc/include/wchar.h (fgetwc_unlocked, fgetws_unlocked,
fputwc_unlocked, fputws_unlocked, getwc_unlocked, getwchar_unlocked,
putwc_unlocked, putwchar_unlocked): Declare.
* libc/stdio/Makefile.am (ELIX_4_SOURCES): Add clearerr_u.c,
feof_u.c, ferror_u.c, fflush_u.c, fgetc_u.c, fgets_u.c, fgetwc_u.c,
fgetws_u.c, fileno_u.c, fputc_u.c, fputs_u.c, fputwc_u.c, fputws_u.c,
fread_u.c, fwrite_u.c, getwc_u.c, getwchar_u.c, putwc_u.c, putwchar_u.c.
Add necessary dependencies.
* libc/stdio/Makefile.in: Regenerate.
* libc/stdio/clearerr.c: Document unlocked variant.
* libc/stdio/clearerr_u.c: New file.
* libc/stdio/feof.c: Document unlocked variant.
* libc/stdio/feof_u.c: New file.
* libc/stdio/ferror.c: Document unlocked variant.
* libc/stdio/ferror_u.c: New file.
* libc/stdio/fflush.c: Add __IMPL_UNLOCKED__ overrides.
Document unlocked variants.
* libc/stdio/fflush_u.c: New file.
* libc/stdio/fgetc.c: Document unlocked variants.
* libc/stdio/fgetc_u.c: New file.
* libc/stdio/fgets.c: Add __IMPL_UNLOCKED__ overrides.
Document unlocked variants.
* libc/stdio/fgets_u.c: New file.
* libc/stdio/fgetwc.c: Document unlocked variants.
(__fgetwc): Make non-static.
* libc/stdio/fgetwc_u.c: New file.
* libc/stdio/fgetws.c: Add __IMPL_UNLOCKED__ overrides.
Document unlocked variants.
* libc/stdio/fgetws_u.c: New file.
* libc/stdio/fileno.c: Document unlocked variant.
* libc/stdio/fileno_u.c: New file.
* libc/stdio/fputc.c: Document unlocked variants.
* libc/stdio/fputc_u.c: New file.
* libc/stdio/fputs.c: Add __IMPL_UNLOCKED__ overrides.
Document unlocked variants.
* libc/stdio/fputs_u.c: New file.
* libc/stdio/fputwc.c: Document unlocked variants.
(__fputwc): Make non-static.
* libc/stdio/fputwc_u.c: New file.
* libc/stdio/fputws.c: Add __IMPL_UNLOCKED__ overrides.
Document unlocked variants.
* libc/stdio/fputws_u.c: New file.
* libc/stdio/fread.c: Add __IMPL_UNLOCKED__ overrides.
Document unlocked variants.
* libc/stdio/fread_u.c: New file.
* libc/stdio/fwrite.c: Add __IMPL_UNLOCKED__ overrides.
Document unlocked variants.
* libc/stdio/fwrite_u.c: New file.
* libc/stdio/getwc_u.c: New file.
* libc/stdio/getwchar.c: Document unlocked variants.
* libc/stdio/getwchar_u.c: New file.
* libc/stdio/local.h: Define locking macros as empty ifdef
__IMPL_UNLOCKED__.
(__fgetwc, __fputwc): Declare.
* libc/stdio/putwc_u.c: New file.
* libc/stdio/putwchar.c: Document unlocked variants.
* libc/stdio/putwchar_u.c: New file.

1 files changed, 48 insertions, 3 deletions

diff --git a/newlib/libc/stdio/fread.c b/newlib/libc/stdio/fread.c
index cf9ab40b7..d55ff66d8 100644
--- a/newlib/libc/stdio/fread.c
+++ b/newlib/libc/stdio/fread.c
@@ -17,22 +17,35 @@
 
 /*
 FUNCTION
-<<fread>>---read array elements from a file
+<<fread>>. <<fread_unlocked>>---read array elements from a file
 
 INDEX
 	fread
 INDEX
+	fread_unlocked
+INDEX
 	_fread_r
+INDEX
+	_fread_unlocked_r
 
 ANSI_SYNOPSIS
 	#include <stdio.h>
 	size_t fread(void *restrict <[buf]>, size_t <[size]>, size_t <[count]>,
 		     FILE *restrict <[fp]>);
 
+	#define _BSD_SOURCE
+	#include <stdio.h>
+	size_t fread_unlocked(void *restrict <[buf]>, size_t <[size]>, size_t <[count]>,
+		     FILE *restrict <[fp]>);
+
 	#include <stdio.h>
 	size_t _fread_r(struct _reent *<[ptr]>, void *restrict <[buf]>,
 	                size_t <[size]>, size_t <[count]>, FILE *restrict <[fp]>);
 
+	#include <stdio.h>
+	size_t _fread_unlocked_r(struct _reent *<[ptr]>, void *restrict <[buf]>,
+	                size_t <[size]>, size_t <[count]>, FILE *restrict <[fp]>);
+
 TRAD_SYNOPSIS
 	#include <stdio.h>
 	size_t fread(<[buf]>, <[size]>, <[count]>, <[fp]>)
@@ -41,6 +54,14 @@ TRAD_SYNOPSIS
 	size_t <[count]>;
 	FILE *<[fp]>;
 
+	#define _BSD_SOURCE
+	#include <stdio.h>
+	size_t fread_unlocked(<[buf]>, <[size]>, <[count]>, <[fp]>)
+	char *<[buf]>;
+	size_t <[size]>;
+	size_t <[count]>;
+	FILE *<[fp]>;
+
 	#include <stdio.h>
 	size_t _fread_r(<[ptr]>, <[buf]>, <[size]>, <[count]>, <[fp]>)
 	struct _reent *<[ptr]>;
@@ -49,6 +70,14 @@ TRAD_SYNOPSIS
 	size_t <[count]>;
 	FILE *<[fp]>;
 
+	#include <stdio.h>
+	size_t _fread_unlocked_r(<[ptr]>, <[buf]>, <[size]>, <[count]>, <[fp]>)
+	struct _reent *<[ptr]>;
+	char *<[buf]>;
+	size_t <[size]>;
+	size_t <[count]>;
+	FILE *<[fp]>;
+
 DESCRIPTION
 <<fread>> attempts to copy, from the file or stream identified by
 <[fp]>, <[count]> elements (each of size <[size]>) into memory,
@@ -58,8 +87,17 @@ starting at <[buf]>.   <<fread>> may copy fewer elements than
 <<fread>> also advances the file position indicator (if any) for
 <[fp]> by the number of @emph{characters} actually read.
 
-<<_fread_r>> is simply the reentrant version of <<fread>> that
-takes an additional reentrant structure pointer argument: <[ptr]>.
+<<fread_unlocked>> is a non-thread-safe version of <<fread>>.
+<<fread_unlocked>> may only safely be used within a scope
+protected by flockfile() (or ftrylockfile()) and funlockfile().  This
+function may safely be used in a multi-threaded program if and only
+if they are called while the invoking thread owns the (FILE *)
+object, as is the case after a successful call to the flockfile() or
+ftrylockfile() functions.  If threads are disabled, then
+<<fread_unlocked>> is equivalent to <<fread>>.
+
+<<_fread_r>> and <<_fread_unlocked_r>> are simply reentrant versions of the
+above that take an additional reentrant structure pointer argument: <[ptr]>.
 
 RETURNS
 The result of <<fread>> is the number of elements it succeeded in
@@ -68,6 +106,8 @@ reading.
 PORTABILITY
 ANSI C requires <<fread>>.
 
+<<fread_unlocked>> is a BSD extension also provided by GNU libc.
+
 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
 */
@@ -78,6 +118,11 @@ Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
 #include <malloc.h>
 #include "local.h"
 
+#ifdef __IMPL_UNLOCKED__
+#define _fread_r _fread_unlocked_r
+#define fread fread_unlocked
+#endif
+
 #ifdef __SCLE
 static size_t
 _DEFUN(crlf_r, (ptr, fp, buf, count, eof),