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Re: Bogus assumption prevents d2u/u2d/conv/etal working on mixed files.
Charles Wilson wrote:
[...]
(2) it's an attempt to prevent users from permanently scrogging binary
files. See: d2u, on a binary file, is an irreversible operation. So,
if you do "d2u *" you'll probably kill something deep inside some binary
file, and you can't fix it -- unless some minimal safeguards are in place.
u2d MAY be reversible -- IF there were no pre-exising \r\n
combinations in the file to begin with -- so when (OMG-fixit-)d2u is
run, obviously the first '\n' is preceeded by a (newly-added) '\r\n', so
the prog merrily replaces ALL '\r\n' with '\n'...which MAY fix your
oops, but maybe not.
So, with the current code, if you snarf the first "line" -- all chars
until the first '\n' -- if it's a binary file the odds are pretty low
that the immediately-preceeding character is a '\r' -- so d2u as
currently coded will bail out, and no harm is done.
It doesn't work so well in the other direction -- by the same logic
above, you'll almost never bail out early if you run 'u2d' on a binary
file -- but if you immediately do a 'd2u' you MIGHT be able to recover.)
[...]
If detection of binary files is desirable, why not use an explicit test with a
more robust methodology? GNU grep detects binary files by looking for a '\0'
byte. Such a test could be used by both d2u and u2d; they could bail out with a
message like "skipping binary file".
Cheers
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