GNU bug report logs - #55952
[PATCH] bindat (strz): Write null terminator after variable length string

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From: Richard Hansen <rhansen <at> rhansen.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 55952 <at> debbugs.gnu.org, monnier <at> iro.umontreal.ca
Subject: bug#55952: [PATCH] bindat (strz): Write null terminator after variable length string
Date: Tue, 14 Jun 2022 16:47:47 -0400

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On 6/14/22 08:52, Eli Zaretskii wrote:
> Thanks, but AFAICT the documentation doesn't describe accurately 
> enough what the modified code does: what if the pre-allocated 
> destination string doesn't have enough storage for the null byte the 
> code adds?

The existing code advances the index for the terminator, it just doesn't write 0 to that byte. So the existing code already signals an error in that case unless the `strz` is the final field.

Regardless, the documentation for `bindat-pack` [1] clearly states that the pre-allocated string must have enough room:

> When pre-allocating, you should make sure `(length raw)` meets or 
> exceeds the total length to avoid an out-of-range error.
[1] https://www.gnu.org/software/emacs/manual/html_node/elisp/Bindat-Functions.html#index-bindat_002dpack

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