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authorChris Johns <chrisj@rtems.org>2017-03-13 12:00:35 -0400
committerGedare Bloom <gedare@rtems.org>2017-05-05 10:34:08 -0400
commit8290f95cbdd5129561d8a375a223055ee7941116 (patch)
tree96d25c735f662d0bed0044d5dc88976b0e8e341b /cpukit/posix/src/mmap.c
parentbd9d5ebc33c35d91b5ca0746b6b78a365eeb726d (diff)
downloadrtems-8290f95cbdd5129561d8a375a223055ee7941116.tar.bz2
posix: Add mmap/unmap support for mapping files.
This version of mmap comes from early work done on the RTL code base circa 2012. Update #2859.
Diffstat (limited to 'cpukit/posix/src/mmap.c')
-rw-r--r--cpukit/posix/src/mmap.c238
1 files changed, 216 insertions, 22 deletions
diff --git a/cpukit/posix/src/mmap.c b/cpukit/posix/src/mmap.c
index 2144d91cae..c05a65e078 100644
--- a/cpukit/posix/src/mmap.c
+++ b/cpukit/posix/src/mmap.c
@@ -1,36 +1,230 @@
-/**
- * @file
- */
-
/*
- * COPYRIGHT (c) 2014.
- * On-Line Applications Research Corporation (OAR).
+ * 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.org/license/LICENSE.
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/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 <rtems/posix/mmanimpl.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 length,
- int prot,
- int flags,
- int fildes,
- off_t off
+ void *addr, size_t len, int prot, int flags, int fildes, off_t off
)
{
- (void) addr;
- (void) length;
- (void) prot;
- (void) flags;
- (void) fildes;
- (void) off;
- return MAP_FAILED;
+ 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;
}