[PATCH] add __ASSUME_MREMAP

[Pino Toscano <toscano dot pino at tiscali dot it>]

Hi,

just like it is done also for other functions, add a __ASSUME_MREMAP in 
kernel-features.h (only in the Linux version) to indicate the 
availability of mremap; this is used to uniform the two existing checks:
- malloc.c enables it if linux is defined
- libio uses _G_HAVE_MREMAP (from _G_config.h)
The comment for __ASSUME_MREMAP in kernel-features.h has been taken from 
malloc.c, just above the HAVE_MREMAP definition.

After this patch, sysdeps/unix/sysv/linux/_G_config.h becomes the same 
as sysdeps/generic/_G_config.h; after review and commit of this, I will 
send a new patch to get rid of the linux _G_config.h.

Thanks,
-- 
Pino Toscano

Add and use __ASSUME_MREMAP for mremap usage

Introduce a __ASSUME_MREMAP symbol to advertize mremap availability, and use
it also to replace _G_HAVE_MREMAP.

2012-11-10  Pino Toscano  <toscano.pino@tiscali.it>

	* sysdeps/unix/sysv/linux/kernel-features.h (__ASSUME_MREMAP): New
	define.
	* malloc/malloc.c: Include <kernel-features.h>.
	[!HAVE_MREMAP] [linux]: Change condition to
	[defined(linux) || defined(__ASSUME_MREMAP)].
	* sysdeps/unix/sysv/linux/_G_config.h (_G_HAVE_MREMAP): Remove.
	* libio/fileops.c: Include <kernel-features.h> unconditionally.
	(mmap_remap_check) [_G_HAVE_MREMAP]: Change condition to
	[__ASSUME_MREMAP].
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -168,7 +168,7 @@
 
     Compilation Environment options:
 
-    HAVE_MREMAP                0 unless linux defined
+    HAVE_MREMAP                0 unless linux or __ASSUME_MREMAP defined
 
     Changing default word sizes:
 
@@ -230,6 +230,8 @@
 
 #include <shlib-compat.h>
 
+#include <kernel-features.h>
+
 /* For uintptr_t.  */
 #include <stdint.h>
 
@@ -495,7 +497,7 @@ void *(*__morecore)(ptrdiff_t) = __defau
 */
 
 #ifndef HAVE_MREMAP
-#ifdef linux
+#if defined(linux) || defined(__ASSUME_MREMAP)
 #define HAVE_MREMAP 1
 #else
 #define HAVE_MREMAP 0
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -37,6 +37,9 @@
    introduced.  If somebody cares these values can afterwards be
    corrected.  */
 
+/* A usable mremap is available since 1.3.77.  */
+#define __ASSUME_MREMAP		1
+
 /* The sendfile syscall was introduced in 2.2.0.  */
 #define __ASSUME_SENDFILE		1
 
--- a/sysdeps/unix/sysv/linux/_G_config.h
+++ b/sysdeps/unix/sysv/linux/_G_config.h
@@ -46,7 +46,6 @@ typedef union
 #define _G_va_list __gnuc_va_list
 
 #define _G_HAVE_MMAP 1
-#define _G_HAVE_MREMAP 1
 
 #define _G_IO_IO_FILE_VERSION 0x20001
 
--- a/libio/fileops.c
+++ b/libio/fileops.c
@@ -39,13 +39,13 @@
 #include <errno.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <kernel-features.h>
 #if _LIBC
 # include "../wcsmbs/wcsmbsload.h"
 # include "../iconv/gconv_charset.h"
 # include "../iconv/gconv_int.h"
 # include <shlib-compat.h>
 # include <not-cancel.h>
-# include <kernel-features.h>
 #endif
 #ifndef errno
 extern int errno;
@@ -658,7 +658,7 @@ mmap_remap_check (_IO_FILE *fp)
 	{
 	  /* The file added some pages.  We need to remap it.  */
 	  void *p;
-#ifdef _G_HAVE_MREMAP
+#ifdef __ASSUME_MREMAP
 	  p = __mremap (fp->_IO_buf_base, ROUNDED (fp->_IO_buf_end
 						   - fp->_IO_buf_base),
 			ROUNDED (st.st_size), MREMAP_MAYMOVE);

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