file->off does not update in LFS_READONLY

[blomnik]

I have this hunk of code

    err = lfs_file_read(&lfs, &f, &container, sizeof(container_t));
    if((size_t)err < sizeof(container_t)) {
      trace_printf("File corrupted: %d\n", err);
      goto application;
    }
    err = lfs_file_seek(&lfs, &f, sizeof(file_header_t), LFS_SEEK_SET);
    if(err < 0) {
      trace_printf("File seek failed: %d\n", err);
      goto application;
    }

    char buf[16];
    int c;
    uint16_t crc = CRC16_INIT;
    while(1) {
      c = lfs_file_read(&lfs, &f, buf, sizeof(buf));
      if(c <= 0) break; // eof

      crc = crc16_ccitt_kermit(crc, buf, c);
    }

Size of container_t is 48 bytes. Size of file_header_t is 16 bytes. Invoking of lfs_file_seek() update file->pos to 16 and file->off still remain 48. So, when I first invoke lfs_file_read() it reads correctly (because file is large enough) but at incorrect position. This is not applicable when LFS_READONLY macro not defined. Is it bug? Is it enough to patch something like this:

static lfs_soff_t lfs_file_rawseek(lfs_t *lfs, lfs_file_t *file,
        lfs_soff_t off, int whence) {
    // ..........

    // update pos
    file->pos = npos;
#ifdef LFS_READONLY
    file->off = npos;
#endif
    return npos;
}

I suppose, that in LFS_READONLY mode internal static function lfs_file_outline() does not invoke and off field does not update.

Thank you.

[thrasher8390]

This seem similar to https://github.com/littlefs-project/littlefs/issues/534. Sorry I don't have any more time to look into this but I figured I'd drop the breadcrumb :)

[blomnik]

Yes, sure it is the same.

[geky]

Hi @blomnik, thanks for creating an issue, sorry about such a late response.

I believe this has actually be fixed in https://github.com/littlefs-project/littlefs/pull/637 (available now in v2.4.2)? Let me know if this isn't the case.