less -r broken with long lines

[Peter Jeremy]

On 2007-Jul-18 21:09:31 +0100, Rui Paulo <rpaulo at fnop.net> wrote:
>It depends on the interpretation. "various display problems may result"
>may very well be a reference to the fact that control characters mangle
>the output. I wasn't expecting long lines to mangle the output. If you
>less -r a file without control characters, but with a least a line wider
>than your screen size, you'll notice the problem.

I think the behaviour of "less" is reasonable.  To correctly work out
how many lines of input will fill the screen, "less" needs to identify
if/where the terminal will split a string of characters into distinct
physical lines.  In the face of arbitrary control sequences, it is
impossible for "less" to determine this since it cannot know how a
particular string will be processed.  (It can't rely on termcap/info
strings because they are unlikely to document all terminal features).

-- 
Peter Jeremy
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