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


Ignore:
Timestamp:
2010-02-10T23:51:23Z (12 years ago)
Author:
Martin Decky <martin@…>
Branches:
lfn, master
Children:
e70edd1
Parents:
b32c604
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:
1 edited

Legend:

Unmodified
Added
Removed
  • uspace/srv/fs/devfs/devfs_ops.c

    rb32c604 red903174  
    3737
    3838#include <ipc/ipc.h>
     39#include <macros.h>
    3940#include <bool.h>
    4041#include <errno.h>
     
    337338}
    338339
    339 static size_t devfs_size_get(fs_node_t *fn)
     340static aoff64_t devfs_size_get(fs_node_t *fn)
    340341{
    341342        return 0;
     
    463464{
    464465        fs_index_t index = (fs_index_t) IPC_GET_ARG2(*request);
    465         off_t pos = (off_t) IPC_GET_ARG3(*request);
     466        aoff64_t pos =
     467            (aoff64_t) MERGE_LOUP32(IPC_GET_ARG3(*request), IPC_GET_ARG4(*request));
    466468       
    467469        if (index == 0) {
     
    597599{
    598600        fs_index_t index = (fs_index_t) IPC_GET_ARG2(*request);
    599         off_t pos = (off_t) IPC_GET_ARG3(*request);
    600        
    601601        if (index == 0) {
    602602                ipc_answer_0(rid, ENOTSUP);
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