Changeset ed903174 in mainline for uspace/srv/fs/fat/fat_fat.h

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/fat/fat_fat.h (modified) (2 diffs)

uspace/srv/fs/fat/fat_fat.h

@@ -69 +69 @@
 
 extern int _fat_block_get(block_t **, struct fat_bs *, dev_handle_t,
-    fat_cluster_t, bn_t, int);
-  
+    fat_cluster_t, aoff64_t, int);
+
 extern int fat_append_clusters(struct fat_bs *, struct fat_node *,
     fat_cluster_t);
@@ -85 +85 @@
     fat_cluster_t, fat_cluster_t);
 extern int fat_fill_gap(struct fat_bs *, struct fat_node *, fat_cluster_t,
-    off_t);
+    aoff64_t);
 extern int fat_zero_cluster(struct fat_bs *, dev_handle_t, fat_cluster_t);
 extern int fat_sanity_check(struct fat_bs *, dev_handle_t);