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2018.11.10 19:39 "[Tiff] Libtiff 4.0.10 is now available", by Bob Friesenhahn
2018.12.12 08:53 "Re: [Tiff] SeekOK and WriteOK", by Emmanuel Cosnard
2018.12.13 11:04 "Re: [Tiff] SeekOK and WriteOK", by Emmanuel Cosnard
2018.12.13 13:13 "Re: [Tiff] SeekOK and WriteOK", by Paavo Helde

2018.12.13 11:04 "Re: [Tiff] SeekOK and WriteOK", by Emmanuel Cosnard


I found out what the problem was: the buffer size I gave in input of the WriteOK was larger than the actual size of the buffer.

What I don't understand is how libtiff does to not crash, but only sometimes return an error (-1), and sometimes, writing the data of the buffer anyway. Do you have any explanation?

Thank you for your help and regards,


De: Emmanuel Cosnard
Envoyé: mercredi 12 décembre 2018 08:53
À: Bob Friesenhahn; Nicolas RUFF
Objet: RE: [Tiff] SeekOK and WriteOK

I actually noticed that I never get any problem with the SeekOK, but only with writeOK.

I sometimes returns -1 although he wrote everything I wanted to, and sometimes returns -1 and doesn't write anything but I have no clue why on some occasions he doesn't write...

De: Bob Friesenhahn <>
Envoyé: mardi 11 décembre 2018 18:54
À: Nicolas RUFF
Objet: Re: [Tiff] SeekOK and WriteOK

On Tue, 11 Dec 2018, Nicolas RUFF wrote:

> This might be by design of the API :)
> lseek() returns -1 in both cases:
> - lseek(-1, SEEK_SET)
> - An error occurred
> You have to clear then check errno to distinguish between cases.

One approach is to call 'lseek(fd,SEEK_CUR)' and verify that the
return value is the expected offset.

Bob Friesenhahn,
GraphicsMagick Maintainer,
Public Key,