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authorSebastian Huber <sebastian.huber@embedded-brains.de>2012-02-21 17:21:05 +0100
committerSebastian Huber <sebastian.huber@embedded-brains.de>2012-03-13 12:24:15 +0100
commit316507ab91ecabe73db1af03d74be398e24837b8 (patch)
tree590dfc503c2755ee657b6361fe8ddf584896a4f8
parente00cca9b74acb6ec67cc9696cd0a005aa3d991c3 (diff)
downloadrtems-316507ab91ecabe73db1af03d74be398e24837b8.tar.bz2
IMFS: Lock the file system during directory reads
Other threads may add or remove directory entries during a read of the directory. Use the file system instance lock for protection.
-rw-r--r--cpukit/libfs/src/imfs/imfs_directory.c36
1 files changed, 15 insertions, 21 deletions
diff --git a/cpukit/libfs/src/imfs/imfs_directory.c b/cpukit/libfs/src/imfs/imfs_directory.c
index 8ef05b4d1d..fc687e4331 100644
--- a/cpukit/libfs/src/imfs/imfs_directory.c
+++ b/cpukit/libfs/src/imfs/imfs_directory.c
@@ -81,34 +81,29 @@ ssize_t imfs_dir_read(
int last_entry;
struct dirent tmp_dirent;
+ rtems_filesystem_instance_lock( &iop->pathinfo );
+
the_jnode = (IMFS_jnode_t *)iop->pathinfo.node_access;
the_chain = &the_jnode->info.directory.Entries;
- if ( rtems_chain_is_empty( the_chain ) )
- return 0;
-
/* Move to the first of the desired directory entries */
- the_node = rtems_chain_first( the_chain );
bytes_transferred = 0;
first_entry = iop->offset;
/* protect against using sizes that are not exact multiples of the */
/* -dirent- size. These could result in unexpected results */
- last_entry = first_entry + (count/sizeof(struct dirent)) * sizeof(struct dirent);
+ last_entry = first_entry
+ + (count / sizeof( struct dirent )) * sizeof( struct dirent );
/* The directory was not empty so try to move to the desired entry in chain*/
for (
- current_entry = 0;
- current_entry < last_entry;
- current_entry = current_entry + sizeof(struct dirent) ){
-
- if ( rtems_chain_is_tail( the_chain, the_node ) ){
- /* We hit the tail of the chain while trying to move to the first */
- /* entry in the read */
- return bytes_transferred; /* Indicate that there are no more */
- /* entries to return */
- }
-
+ current_entry = 0,
+ the_node = rtems_chain_first( the_chain );
+ current_entry < last_entry
+ && !rtems_chain_is_tail( the_chain, the_node );
+ current_entry += sizeof( struct dirent ),
+ the_node = rtems_chain_next( the_node )
+ ) {
if( current_entry >= first_entry ) {
/* Move the entry to the return buffer */
tmp_dirent.d_off = current_entry;
@@ -122,14 +117,13 @@ ssize_t imfs_dir_read(
(void *)&tmp_dirent,
sizeof( struct dirent )
);
- iop->offset = iop->offset + sizeof(struct dirent);
- bytes_transferred = bytes_transferred + sizeof( struct dirent );
+ iop->offset += sizeof( struct dirent );
+ bytes_transferred += sizeof( struct dirent );
}
-
- the_node = the_node->next;
}
- /* Success */
+ rtems_filesystem_instance_unlock( &iop->pathinfo );
+
return bytes_transferred;
}