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Subject: |
bug in 'diff -B' |
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Date: |
Thu, 4 Aug 2016 21:43:45 +0000 |
Hello,
When diffing an empty file against a one-byte file using -B
(--ignore-blank-lines), diff incorrectly reports that the files are identical,
even though they aren't even the same size. The problem does not occur with
files of 2 bytes or longer. I tested this with diffutils 2.8, 3.2 and 3.3.
How to reproduce:
# create a one-byte file "foo"
deedwl262 [~/work/test] mzieg 09:17 PM $ echo -n x > foo
# create a zero-byte file "bar"
deedwl262 [~/work/test] mzieg 09:17 PM $ echo -n > bar
# confirm file sizes
deedwl262 [~/work/test] mzieg 09:18 PM $ ls -la
-rw-rw-r-- 1 mzieg unixusers 0 Aug 4 21:18 bar
-rw-rw-r-- 1 mzieg unixusers 1 Aug 4 21:17 foo
# verify "diff" works as expected
deedwl262 [~/work/test] mzieg 09:18 PM $ diff foo bar
1d0
< x
\ No newline at end of file
# verify "diff -w" works as expected
deedwl262 [~/work/test] mzieg 09:18 PM $ diff -w foo bar
1d0
< x
\ No newline at end of file
# verify "diff -b" works as expected
deedwl262 [~/work/test] mzieg 09:18 PM $ diff -b foo bar
1d0
< x
\ No newline at end of file
# HERE IS THE PROBLEM: diff -B does NOT work as expected
deedwl262 [~/work/test] mzieg 09:18 PM $ diff -B foo bar
# change "foo" to a 2-byte file
deedwl262 [~/work/test] mzieg 09:18 PM $ echo -n xy > foo
# now "diff -B" works as expected
deedwl262 [~/work/test] mzieg 09:19 PM $ diff -B foo bar
1d0
< xy
\ No newline at end of file
Regards,
Mark Zieg
address@hidden
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--- Begin Message ---
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Subject: |
Re: [bug-diffutils] bug#24154: bug in 'diff -B' |
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Date: |
Thu, 4 Aug 2016 16:30:43 -0700 |
On Thu, Aug 4, 2016 at 2:43 PM, Zieg, Mark (KSC-ESC-624)[VENCORE-ESC]
<address@hidden> wrote:
> When diffing an empty file against a one-byte file using -B
> (--ignore-blank-lines), diff incorrectly reports that the files are
> identical, even though they aren't even the same size. The problem does not
> occur with files of 2 bytes or longer. I tested this with diffutils 2.8, 3.2
> and 3.3.
...
> # HERE IS THE PROBLEM: diff -B does NOT work as expected
> deedwl262 [~/work/test] mzieg 09:18 PM $ diff -B foo bar
Thank you for the report. I confirm it was a problem with diffutils-3.3:
$ /usr/bin/diff --version|head -1
diff (GNU diffutils) 3.3
$ printf 1 > 1; : > 0; /usr/bin/diff -B 0 1
$ printf 1 > 1; : > 0; /usr/bin/diff -B 1 0
$
It was fixed with this commit, which will be part of the imminent
diffutils-3.4 release:
commit d2fd9d4683ef60c259a3b426f71cef1b89ff383d
Author: Paul Eggert <address@hidden>
Date: Wed Sep 3 15:58:03 2014 -0700
diff: fix bug with diff -B and incomplete lines
Reported by Navin Kabra via Eric Blake in:
http://bugs.gnu.org/18402
* src/util.c (analyze_hunk): Don't mishandle incomplete
lines at end of file.
* tests/no-newline-at-eof: Test for the bug.
So I've marked this auto-created "issue" as resolved.
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