Changeset ed903174 in mainline for uspace/lib/libblock/libblock.h

Timestamp:

2010-02-10T23:51:23Z (14 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/lib/libblock/libblock.h (modified) (3 diffs)

uspace/lib/libblock/libblock.h

@@ -74 +74 @@
         dev_handle_t dev_handle;
         /** Block offset on the block device. Counted in 'size'-byte blocks. */
-        bn_t boff;
+        aoff64_t boff;
         /** Size of the block. */
         size_t size;
@@ -96 +96 @@
 extern void block_fini(dev_handle_t);
 
-extern int block_bb_read(dev_handle_t, bn_t);
+extern int block_bb_read(dev_handle_t, aoff64_t);
 extern void *block_bb_get(dev_handle_t);
 
@@ -102 +102 @@
 extern int block_cache_fini(dev_handle_t);
 
-extern int block_get(block_t **, dev_handle_t, bn_t, int);
+extern int block_get(block_t **, dev_handle_t, aoff64_t, int);
 extern int block_put(block_t *);
 
-extern int block_seqread(dev_handle_t, off_t *, size_t *, off_t *, void *,
+extern int block_seqread(dev_handle_t, size_t *, size_t *, aoff64_t *, void *,
     size_t);
 
 extern int block_get_bsize(dev_handle_t, size_t *);
-extern int block_get_nblocks(dev_handle_t, bn_t *);
-extern int block_read_direct(dev_handle_t, bn_t, size_t, void *);
-extern int block_write_direct(dev_handle_t, bn_t, size_t, const void *);
+extern int block_get_nblocks(dev_handle_t, aoff64_t *);
+extern int block_read_direct(dev_handle_t, aoff64_t, size_t, void *);
+extern int block_write_direct(dev_handle_t, aoff64_t, size_t, const void *);
 
 #endif