bug#73360: Error when a long list is provided to grep with "--binary-files=without-match" option

[Paul Eggert]

On 2024-09-20 22:41, Paul Eggert wrote:
> I have the sneaking suspicion that the script is assuming properties of 
> 'grep' that are not documented and that are not guaranteed.

In looking into the code a bit more, I can see some places where that is 
what is happening.

A couple of things.

First, grep 3.11 uses buffer sizes that depend on earlier files that it 
has scanned, and this affects whether grep decides later files are 
binary. This can lead to the sort of confusion that you mentioned. There 
are performance reasons to think that grep should not grow buffer sizes 
for later files merely because earlier files had very long lines, as 
huge buffers can hurt performance; so I installed onto the development 
repository on Savannah the first attached patch to fix that. As a side 
effect this may fix the symptoms you observed.

Second, 'grep' is not a good tool for determining whether a file is text 
or binary, since the definition of "text" vs "binary" is 
application-specific and grep's definition is suitable for 'grep' and 
it's problematic to use it elsewhere. I installed the second attached 
patch to try to document this better.

Hope this helps.

Boldly closing this bug as fixed; if I'm wrong we can reopen it.

0001-grep-avoid-huge-reads.patch
Description: Text Data

0002-doc-warn-re-using-grep-to-detect-binary-files.patch
Description: Text Data