Changeset ed903174 in mainline for uspace/srv/fs/devfs/devfs_ops.c

Timestamp:

2010-02-10T23:51:23Z (15 years ago)

Author:

Martin Decky <martin@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

e70edd1

Parents:

b32c604f

Message:

implement support for 64bit file offsets

• the libc API is a small deviation from standard, but we have no reason to keep a strict backward compatibility with ancient code so far
  • the basic signed 64bit offset type is called off64_t
    • lseek() and fseek() take off64_t arguments (since the argument represents a relative offset)
    • ftell() returns off64_t values (since it is a wrapper of lseek())
    • vfs_seek() implementation supports negative offsets when SEEK_CUR and SEEK_END is used
  • aoff64_t is used for internal unsigned representation of sizes (in bytes, blocks, etc.) and absolute offsets
    • mmap() and ftruncate() take aoff64_t arguments (since the full range of the absolute file offset should be used here)
    • struct stat stores the file size as aoff64_t
  • in both cases the explicit range of the types shown in the names is helpful for proper filesystem and IPC interaction
  • note: size_t should be used only for representing in-memory sizes and offsets, not device and file-related information, and vice versa
    • the code base still needs a thorough revision with respect to this rule
  • PRIdOFF64 and PRIuOFF64 can be used for printing the offsets
• VFS_OUT_LOOKUP returns the 64bit file size in two IPC arguments
  • since all 5 IPC arguments have already been taken, the fs_handle is returned as the return value (fs_handle has only 16 bits, thus the return value can be used for both indicating errors as negative values and returning positive handles)
• VFS_OUT_READ and VFS_OUT_WRITE use aoff64_t absolute offsets split into two IPC arguments

replace bn_t with aoff64_t as a generic 64bit bytes/block counter type

note: filesystem drivers need to be revised with respect to make sure that all out-of-range checks are correct (especially w.r.t. file and block offsets)

File:

• uspace/srv/fs/devfs/devfs_ops.c (modified) (4 diffs)

uspace/srv/fs/devfs/devfs_ops.c

@@ -37 +37 @@
 
 #include <ipc/ipc.h>
+#include <macros.h>
 #include <bool.h>
 #include <errno.h>
@@ -337 +338 @@
 }
 
-static size_t devfs_size_get(fs_node_t *fn)
+static aoff64_t devfs_size_get(fs_node_t *fn)
 {
         return 0;
@@ -463 +464 @@
 {
         fs_index_t index = (fs_index_t) IPC_GET_ARG2(*request);
-        off_t pos = (off_t) IPC_GET_ARG3(*request);
+        aoff64_t pos =
+            (aoff64_t) MERGE_LOUP32(IPC_GET_ARG3(*request), IPC_GET_ARG4(*request));
         
         if (index == 0) {
@@ -597 +599 @@
 {
         fs_index_t index = (fs_index_t) IPC_GET_ARG2(*request);
-        off_t pos = (off_t) IPC_GET_ARG3(*request);
-        
         if (index == 0) {
                 ipc_answer_0(rid, ENOTSUP);