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/*
** PJL C++ Library
** mmap_file.c
**
** Copyright (C) 1998 Paul J. Lucas
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
// standard
#include <cerrno>
#include <fcntl.h> /* for open(2), O_RDONLY, etc */
#include <time.h> /* needed by sys/resource.h */
#include <sys/time.h> /* needed by FreeBSD systems */
#include <sys/resource.h> /* for get/setrlimit(2) */
#include <sys/stat.h> /* for stat(2) */
#include <unistd.h> /* for close(2) */
#if defined( MULTI_THREADED ) && defined( RLIMIT_VMEM )
#include <pthread.h>
#endif
// local
#include "mmap_file.h"
#include "platform.h"
using namespace PJL;
using namespace std;
#ifdef RLIMIT_VMEM /* SVR4 */
//*****************************************************************************
//
// SYNOPSIS
//
extern "C" void max_out_limits()
//
// DESCRIPTION
//
// Max-out our memory-mapped address space since we can potentially
// mmap(2) very large files.
//
// NOTE
//
// This function is declared extern "C" since it is called via the C
// library function pthread_once() (if MULTI_THREADED is defined) and,
// because it's a C function, it expects C linkage.
//
//*****************************************************************************
{
struct rlimit r;
::getrlimit( RLIMIT_VMEM, &r );
r.rlim_cur = r.rlim_max;
::setrlimit( RLIMIT_VMEM, &r );
}
#endif /* RLIMIT_VMEM */
//*****************************************************************************
//
// SYNOPSIS
//
int mmap_file::behavior( behavior_type behavior ) const
//
// DESCRIPTION
//
// Give memory-paging strategy advise.
//
// PARAMETERS
//
// behavior The behavior to use.
//
// RETURN VALUE
//
// Returns 0 only if successful; otherwise return errno.
//
//*****************************************************************************
{
#ifndef __APPLE__
//
// As of Mac OS X 10.2.1 (Darwin 6.1), madvise(2) seems broken, so don't
// bother.
//
#ifndef PJL_NO_MADVISE
if ( ::madvise( static_cast<caddr_t>( addr_ ), size_, behavior ) == -1 )
return errno_ = errno;
#endif
#endif /* __APPLE__ */
return 0;
}
//*****************************************************************************
//
// SYNOPSIS
//
void mmap_file::close()
//
// DESCRIPTION
//
// Munmaps and closes a file previously opened and mmapped by
// mmap_file::open().
//
// SEE ALSO
//
// close(2), mmap_file::open(3), munmap(2)
//
//*****************************************************************************
{
if ( addr_ )
::munmap( static_cast<char*>( addr_ ), size_ );
if ( fd_ )
::close( fd_ );
init();
}
//*****************************************************************************
//
// SYNOPSIS
//
void mmap_file::init()
//
// DESCRIPTION
//
// Initialize an instance of mmap_file.
//
//*****************************************************************************
{
#ifdef RLIMIT_VMEM /* SVR4 */
//
// This OS defines a separate resource limit for memory-mapped address
// space as opposed to data, stack, or heap space. Anyway, we want to max
// it out so we can mmap(2) very large files.
//
#ifdef MULTI_THREADED
static pthread_once_t max_out = PTHREAD_ONCE_INIT;
::pthread_once( &max_out, max_out_limits );
#else
static bool maxed_out;
if ( !maxed_out ) {
max_out_limits();
maxed_out = true;
}
#endif /* MULTI_THREADED */
#endif /* RLIMIT_VMEM */
size_ = 0;
fd_ = 0;
addr_ = 0;
errno_ = 0;
}
//*****************************************************************************
//
// SYNOPSIS
//
bool mmap_file::open( char const *path, ios::openmode mode )
//
// DESCRIPTION
//
// Open and mmap a file.
//
// RETURN VALUE
//
// Returns true only if the file was mmapped successfully.
//
// SEE ALSO
//
// mmap(2), open(2), stat(2)
//
//*****************************************************************************
{
close();
struct stat stat_buf;
if ( ::stat( path, &stat_buf ) == -1 ) {
errno_ = errno;
return false;
}
int flags = 0;
if ( mode & ios::in ) flags |= O_RDONLY;
if ( mode & ios::out ) flags |= O_WRONLY;
if ( ( fd_ = ::open( path, flags ) ) == -1 ) {
fd_ = 0;
errno_ = errno;
return false;
}
int prot = PROT_NONE;
if ( mode & ios::in ) prot |= PROT_READ;
if ( mode & ios::out ) prot |= PROT_WRITE;
if ( !( size_ = stat_buf.st_size ) ) {
#ifdef ENODATA
errno_ = ENODATA;
#else
//
// For BSD systems, we're forced to use something other than ENODATA
// since it's not available. Unfortunately, there isn't something good
// to use: EINVAL is the least bad.
//
errno_ = EINVAL;
#endif /* ENODATA */
return false;
}
addr_ = ::mmap( 0, size_, prot, MAP_SHARED, fd_, 0 );
if ( addr_ == MAP_FAILED ) {
addr_ = 0;
errno_ = errno;
return false;
}
return behavior( bt_normal ) == 0;
}
/* vim:set et sw=4 ts=4: */
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