[debbugs-tracker] bug#16559: closed (Bug report for 'head' (and 'wc' et. al.))

[GNU bug Tracking System]

Your message dated Wed, 29 Jan 2014 11:55:53 +0000
with message-id <address@hidden>
and subject line Re: bug#16329: Acknowledgement (`head --lines=-0' prints 
nothing if no newline at the EOF)
has caused the debbugs.gnu.org bug report #16329,
regarding Bug report for 'head' (and 'wc' et. al.)
to be marked as done.

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16329: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=16329
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--- Begin Message --- Subject: Bug report for 'head' (and 'wc' et. al.) Date: Sun, 26 Jan 2014 10:28:50 -0430 Caracas, Sunday 26th, 2014

Ref: Bug report for 'head' (and 'wc' et. al.)

Dear friends:

  Please find attached the text file 'head-tst.txt'
 
  As you easily can see, the following command fails and do not print
anything, even if the file has:  6 lines,  49 words and  250 chars:

  'head -n -0 head-tst.txt'

  The last line on the file does NOT end with a '\n', and this seems
to be the base of the problem. If you add the last '\n', 'head' works
pretty fine.

  So this seems to be a problem with the definition of a 'text line':
I guess that a line that has around 68 normal chars and 13 spaces, is
a good candidate to be considered as a line.

  I found the same problem in several other core utils, being the
most remarcable 'wc'. If you executes:

  'wc head-tst.txt'

  you will get:

    5  49 250 head-tst.txt

  what is wrong, as the file has six (6) lines instead of five (5).
The last one lines is missing due to the fact that it does not
include a '\n' at the end.

  In 1998 I fix 'wc', and I have attached 'wc-fix.c' including only
the most remarkable aspects, in case it could be of any help.


Best regards,

Luis G. Uribe C.

---

Attachments inside 'head-tst.zip':
- 'head-tst.txt': text file that makes 'head' core utility to fail
- 'wc-fix.c':     fix to same problem, applyied to 'wc' in 1998

Software ID:
   GNU coreutils 8.15  January 2012  HEAD(1)
   (Cygwin)

--- End Message ---

--- Begin Message --- Subject: Re: bug#16329: Acknowledgement (`head --lines=-0' prints nothing if no newline at the EOF) Date: Wed, 29 Jan 2014 11:55:53 +0000 User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2

On 01/03/2014 08:40 PM, Алексей Шилин wrote:
> Looks like I was overly cautious about decrementing an unsigned...
> 
> size_t n = bytes_read;
> while (n)
>   {
>     if (all_lines)
>       n -= n ? 1 : 0;        // ...here.
>     else
> 
> As it is under `while (n)' statement, n is always true here, and thus the 
> ternary operator, though makes no
> harm, is needless, and the whole line can be replaced with just `n--;'. Sorry 
> for that.
> 
> The fixed version of the original patch is attached.
> 

I've updated the patch to also handle the pipe case,
and I added a test. Will push soon.

thanks,
Pádraig.

head--lines-0.patch
Description: Text Data

--- End Message ---