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Changeset ed903174 in mainline for uspace/app/mkfat/mkfat.c

2010-02-10T23:51:23Z (12 years ago)
Martin Decky <martin@…>
lfn, master

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)

1 edited


  • uspace/app/mkfat/mkfat.c

    rb32c604 red903174  
    9898        size_t block_size;
    9999        char *endptr;
    100         bn_t dev_nblocks;
     100        aoff64_t dev_nblocks;
    102102        cfg.total_sectors = 0;
    160160                printf(NAME ": Warning, failed to obtain block device size.\n");
    161161        } else {
    162                 printf(NAME ": Block device has %" PRIuBN " blocks.\n",
     162                printf(NAME ": Block device has %" PRIuOFF64 " blocks.\n",
    163163                    dev_nblocks);
    164164                cfg.total_sectors = dev_nblocks;
    236236static int fat_blocks_write(struct fat_params const *par, dev_handle_t handle)
    238         bn_t addr;
     238        aoff64_t addr;
    239239        uint8_t *buffer;
    240240        int i;
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