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/*
* mmap() - POSIX 1003.1b 6.3.1 - map pages of memory
*
* COPYRIGHT (c) 2012.
* Chris Johns (chrisj@rtems.org)
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems.h>
#include <errno.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include "rtems/libio_.h"
#include "mmap-internal.h"
#define RTEMS_MUTEX_ATTRIBS \
(RTEMS_PRIORITY | RTEMS_SIMPLE_BINARY_SEMAPHORE | \
RTEMS_NO_INHERIT_PRIORITY | RTEMS_NO_PRIORITY_CEILING | RTEMS_LOCAL)
/**
* Mmap chain of mappings.
*/
rtems_chain_control mmap_mappings;
/**
* The id of the MMAP lock.
*/
static rtems_id mmap_mappings_lock;
/**
* Create the lock.
*/
static
bool mmap_mappings_lock_create(
void
)
{
/*
* Lock the mapping table. We only create a lock if a call is made. First we
* test if a mapping lock is present. If one is present we lock it. If not
* the libio lock is locked and we then test the mapping lock again. If not
* present we create the mapping lock then release libio lock.
*/
if ( mmap_mappings_lock == 0 ) {
rtems_status_code sc = RTEMS_SUCCESSFUL;
rtems_chain_initialize_empty( &mmap_mappings );
rtems_semaphore_obtain( rtems_libio_semaphore,
RTEMS_WAIT, RTEMS_NO_TIMEOUT );
if ( mmap_mappings_lock == 0 )
sc = rtems_semaphore_create( rtems_build_name( 'M', 'M', 'A', 'P' ),
1,
RTEMS_MUTEX_ATTRIBS,
RTEMS_NO_PRIORITY,
&mmap_mappings_lock );
rtems_semaphore_release( rtems_libio_semaphore );
if ( sc != RTEMS_SUCCESSFUL ) {
errno = EINVAL;
return false;
}
}
return true;
}
bool mmap_mappings_lock_obtain(
void
)
{
if ( mmap_mappings_lock_create( ) ) {
rtems_status_code sc;
sc = rtems_semaphore_obtain( mmap_mappings_lock,
RTEMS_WAIT, RTEMS_NO_TIMEOUT );
if ( sc != RTEMS_SUCCESSFUL ) {
errno = EINVAL;
return false;
}
}
return true;
}
bool mmap_mappings_lock_release(
void
)
{
rtems_status_code sc;
sc = rtems_semaphore_release( mmap_mappings_lock );
if (( sc != RTEMS_SUCCESSFUL ) && ( errno == 0 )) {
errno = EINVAL;
return false;
}
return true;
}
void *mmap(
void *addr, size_t len, int prot, int flags, int fildes, off_t off
)
{
struct stat sb;
mmap_mapping* mapping;
ssize_t r;
/*
* Clear errno.
*/
errno = 0;
/*
* Get a stat of the file to get the dev + inode number and to make sure the
* fd is ok. The normal libio calls cannot be used because we need to return
* MAP_FAILED on error and they return -1 directly without coming back to
* here.
*/
if ( fstat( fildes, &sb ) < 0 ) {
errno = EBADF;
return MAP_FAILED;
}
if ( len == 0 ) {
errno = EINVAL;
return MAP_FAILED;
}
/*
* Check the type of file we have and make sure it is supported.
*/
if ( S_ISDIR( sb.st_mode ) || S_ISLNK( sb.st_mode )) {
errno = ENODEV;
return MAP_FAILED;
}
/*
* We can provide read, write and execute because the memory in RTEMS does
* not normally have protections but we cannot hide access to memory.
*/
if ( prot == PROT_NONE ) {
errno = EINVAL;
return MAP_FAILED;
}
/*
* Check to see if the mapping is valid for the file.
*/
if ( S_ISREG( sb.st_mode )
&& (( off >= sb.st_size ) || (( off + len ) >= sb.st_size ))) {
errno = EOVERFLOW;
return MAP_FAILED;
}
/*
* Obtain the mmap lock. Sets errno on failure.
*/
if ( !mmap_mappings_lock_obtain( ) )
return MAP_FAILED;
if (( flags & MAP_FIXED ) == MAP_FIXED ) {
rtems_chain_node* node = rtems_chain_first (&mmap_mappings);
while ( !rtems_chain_is_tail( &mmap_mappings, node )) {
/*
* If the map is fixed see if this address is already mapped. At this
* point in time if there is an overlap in the mappings we return an
* error.
*/
mapping = (mmap_mapping*) node;
if ( ( addr >= mapping->addr ) &&
( addr < ( mapping->addr + mapping->len )) ) {
mmap_mappings_lock_release( );
errno = ENXIO;
return MAP_FAILED;
}
node = rtems_chain_next( node );
}
}
mapping = malloc( sizeof( mmap_mapping ));
if ( !mapping ) {
mmap_mappings_lock_release( );
errno = ENOMEM;
return NULL;
}
memset( mapping, 0, sizeof( mmap_mapping ));
mapping->len = len;
mapping->flags = flags;
if (( flags & MAP_FIXED ) != MAP_FIXED ) {
mapping->addr = malloc( len );
if ( !mapping->addr ) {
mmap_mappings_lock_release( );
free( mapping );
errno = ENOMEM;
return MAP_FAILED;
}
/*
* Do not seek on character devices, pipes or sockets.
*/
if ( S_ISREG( sb.st_mode ) || S_ISBLK( sb.st_mode ) ) {
if ( lseek( fildes, off, SEEK_SET ) < 0 ) {
mmap_mappings_lock_release( );
free( mapping->addr );
free( mapping );
return MAP_FAILED;
}
}
}
r = read( fildes, mapping->addr, len );
if ( r != len ) {
mmap_mappings_lock_release( );
free( mapping->addr );
free( mapping );
errno = ENXIO;
return MAP_FAILED;
}
rtems_chain_append( &mmap_mappings, &mapping->node );
mmap_mappings_lock_release( );
return mapping->addr;
}
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