hSeek on text files

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Fri Jul 28 09:09:40 EDT 2006

On Fri, 2006-07-28 at 15:10 +0400, Bulat Ziganshin wrote:

> after writing this letter, i added one more comment to my
> internal documentation - "hRewind and seeking to EOF will be also
> useful". about fseek - i don't see an easy way to implement it. if
> your translated data are already in buffer, then fseek can't return
> just file position corresponding to buffer start + current offset in
> buffer. btw, the same problem arises when we want to use UTF-8 or some
> other Char<->Byte translation with buffered I/O (using iconv, f.e.)
> so, for translated text
> 1) we can implement hRewind/hSeekToEOF
> 2) we can implement some form of hSavePosition/hRestorePosition if
> this position will include tuple (file position of buffer start, offset
> in buffer)
> 3) we can implement tell/seek functionality but this will be slow

How about an inefficient seek that just does a linear scan from the
beginning of the file counting translated characters?

Then the odd case of seek on a text file is penalised rather than doing
no buffering on text files which penalises the normal case.


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