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, 22 insertions, 1 deletions

diff --git a/newlib/libc/stdio/clearerr.c b/newlib/libc/stdio/clearerr.c
index ed4603ba2..9bf0837f5 100644
--- a/newlib/libc/stdio/clearerr.c
+++ b/newlib/libc/stdio/clearerr.c
@@ -17,20 +17,31 @@
 
 /*
 FUNCTION
-<<clearerr>>---clear file or stream error indicator
+<<clearerr>>, <<clearerr_unlocked>>---clear file or stream error indicator
 
 INDEX
 	clearerr
+INDEX
+	clearerr_unlocked
 
 ANSI_SYNOPSIS
 	#include <stdio.h>
 	void clearerr(FILE *<[fp]>);
 
+	#define _BSD_SOURCE
+	#include <stdio.h>
+	void clearerr_unlocked(FILE *<[fp]>);
+
 TRAD_SYNOPSIS
 	#include <stdio.h>
 	void clearerr(<[fp]>)
 	FILE *<[fp]>;
 
+	#define _BSD_SOURCE
+	#include <stdio.h>
+	void clearerr_unlocked(<[fp]>)
+	FILE *<[fp]>;
+
 DESCRIPTION
 The <<stdio>> functions maintain an error indicator with each file
 pointer <[fp]>, to record whether any read or write errors have
@@ -42,6 +53,14 @@ Use <<clearerr>> to reset both of these indicators.
 
 See <<ferror>> and <<feof>> to query the two indicators.
 
+<<clearerr_unlocked>> is a non-thread-safe version of <<clearerr>>.
+<<clearerr_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
+<<clearerr_unlocked>> is equivalent to <<clearerr>>.
 
 RETURNS
 <<clearerr>> does not return a result.
@@ -49,6 +68,8 @@ RETURNS
 PORTABILITY
 ANSI C requires <<clearerr>>.
 
+<<clearerr_unlocked>> is a BSD extension also provided by GNU libc.
+
 No supporting OS subroutines are required.
 */