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libsst-os/SST_Mmap_POSIX.c

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+/*
+	SST_Mmap_POSIX.c
+	Author: Patrick Baggett <ptb1@762studios.com>
+	Created: 12/23/2011
+
+	Purpose: 
+
+	libsst-os memory mapped file I/O functions for POSIX
+
+	License:
+
+	This program is free software. It comes without any warranty, to
+	the extent permitted by applicable law. You can redistribute it
+	and/or modify it under the terms of the Do What The Fuck You Want
+	To Public License, Version 2, as published by Sam Hocevar. See
+	http://sam.zoy.org/wtfpl/COPYING for more details.
+
+*/
+
+#include "POSIXPrivate.h"
+#include <sys/stat.h>
+#include <SST/SST_Mmap.h>
+#include <SST/SST_SysMem.h> /* SST_PROTECT_XXXXX constants, SST_OS_GetPageSize() */
+#include <SST/SST_Assert.h>
+
+void __libsst_init_mmapsize() { /* Not used on POSIX */ }
+
+/******************************************************************************/
+
+uint32_t SST_OS_GetMmapGranularity(void)
+{
+	return SST_OS_GetPageSize();
+}
+
+/******************************************************************************/
+
+SST_MemoryMap SST_OS_CreateMmap(SST_File file, uint64_t offset, size_t mapLength, int mode)
+{
+	SST_File_POSIX* fp = (SST_File_POSIX*)file;
+	SST_MemoryMap_POSIX* mm;
+	int access = 0;
+	void* ptr;
+	off_t off;
+
+	SST_OS_DebugAssert(file != NULL, "File handle may not be NULL");
+	SST_OS_DebugAssert((mode & (~(SST_PROTECT_READ|SST_PROTECT_WRITE|SST_PROTECT_EXEC))) == 0, "The mode bits may only contain SST_PROTECT_READ/WRITE/EXEC and nothing else");
+	SST_OS_DebugAssert((offset & (SST_OS_GetMmapGranularity()-1)) == 0, "Offset must be aligned to system granularity. Use SST_OS_GetMmapGranuality() to determine this");
+	SST_OS_DebugAssert( (offset == 0 && mapLength == 0) || mapLength > 0, "Map length must be non-zero OR offset and length must both be zero (map whole file)");
+
+	if(mode & SST_PROTECT_READ)
+		access |= PROT_READ;;
+	if(mode & SST_PROTECT_WRITE) 
+		access |= PROT_WRITE;
+	if(mode & SST_PROTECT_EXEC)
+		access |= PROT_EXEC;
+	
+	off = (off_t)offset;
+	
+	/* Map whole file */
+	if(mapLength == 0)
+	{
+		struct stat s;
+		if(fstat(fp->fd, &s) == 0)
+			mapLength = (size_t)s.st_size;
+		else /* fstat() failed, try lseek() */
+		{
+			off_t here, end;
+			
+			here = lseek(fp->fd, 0, SEEK_CUR);
+			end = lseek(fp->fd, 0, SEEK_END);
+			
+			/* failed? */
+			if(here == (off_t)-1 || end == (off_t)-1)
+				return NULL;
+			
+			mapLength = (size_t)end;
+			
+			/* Restore file position (not that it matters much if you mmap() the whole thing) */
+			lseek(fp->fd, here, SEEK_SET);
+		}
+		
+	}
+	
+	ptr = mmap(NULL, mapLength, access, MAP_SHARED, fp->fd, off);
+		
+	if(ptr == MAP_FAILED)
+		return NULL;
+
+	/* Allocate a memory map region */
+	mm = (SST_MemoryMap_POSIX*)malloc(sizeof(SST_MemoryMap_POSIX));
+	if(mm == NULL)
+	{
+		munmap(ptr, mapLength);
+		return NULL;
+	}
+
+	mm->offset = offset;
+	mm->len = mapLength;
+	mm->base = ptr;
+	#ifdef _DEBUG
+	mm->owner = fp;
+	fp->nrMmaps++;
+	#endif
+
+	return (SST_MemoryMap)mm;
+}
+
+/******************************************************************************/
+
+void SST_OS_DestroyMmap(SST_MemoryMap mappedRegion)
+{
+	SST_MemoryMap_POSIX* mm = (SST_MemoryMap_POSIX*)mappedRegion;
+
+	SST_OS_DebugAssert(mappedRegion != NULL, "Memory map handle may not be NULL");
+
+	munmap(mm->base, mm->len);
+
+	#ifdef _DEBUG
+	mm->base = NULL;
+	mm->owner->nrMmaps--;
+	#endif
+
+	free(mm);
+}
+
+/******************************************************************************/
+
+void* SST_OS_GetMmapBase(SST_MemoryMap mappedRegion)
+{
+	SST_MemoryMap_POSIX* mm = (SST_MemoryMap_POSIX*)mappedRegion;
+
+	SST_OS_DebugAssert(mappedRegion != NULL, "Memory map handle may not be NULL");
+
+	return mm->base;
+}
+
+/******************************************************************************/
+
+size_t SST_OS_GetMmapSize(SST_MemoryMap mappedRegion)
+{
+	SST_MemoryMap_POSIX* mm = (SST_MemoryMap_POSIX*)mappedRegion;
+
+	SST_OS_DebugAssert(mappedRegion != NULL, "Memory map handle may not be NULL");
+
+	return mm->len;
+}
+
+/******************************************************************************/
+
+uint64_t SST_OS_GetMmapOffset(SST_MemoryMap mappedRegion)
+{
+	SST_MemoryMap_POSIX* mm = (SST_MemoryMap_POSIX*)mappedRegion;
+
+	SST_OS_DebugAssert(mappedRegion != NULL, "Memory map handle may not be NULL");
+
+	return mm->offset;
+}
+
+/******************************************************************************/
+
+void SST_OS_SyncMmap(SST_MemoryMap mappedRegion)
+{
+	SST_MemoryMap_POSIX* mm = (SST_MemoryMap_POSIX*)mappedRegion;
+
+	SST_OS_DebugAssert(mappedRegion != NULL, "Memory map handle may not be NULL");
+
+	/* Synchronize with the OS, but do so async */
+	msync(mm->base, mm->len, MS_ASYNC);
+}
+