Re : Bash scripting and large files: input with the read builtin from a redirection gives unexpected result with files larger than 2GB.

[Jean-François Gagné]

Hi Andreas,

The patch worked when applied on bash 4.1.0 :
jgagne@myhost:/home/jgagne/tmp$ echo ${BASH_VERSINFO[@]}
>4 1 0 1 release x86_64-unknown-linux-gnu
 
It also works on bash 4.2.0:
jgagne@myhost:/home/jgagne/tmp$ echo ${BASH_VERSINFO[@]}
>4 2 0 1 release x86_64-unknown-linux-gnu

I also tested the patch on bash 4.1.11 and 4.2.20, and the bug is reproduced 
before applying the batch, and is gone after:
jgagne@myhost:/home/jgagne/tmp/bash-4.1$ echo ${BASH_VERSINFO[@]}
>4 1 11 5 release x86_64-unknown-linux-gnu
>
>
>jgagne@myhost:/home/jgagne/tmp$ echo ${BASH_VERSINFO[@]}
>4 2 20 2 release x86_64-unknown-linux-gnu

So no doubts left, your patch is the solution to this bug.

Thanks and regards,

Jean-François Gagné


________________________________
 De : Andreas Schwab <schwab@linux-m68k.org>
À : Chet Ramey <chet.ramey@case.edu> 
Cc : Jean-François Gagné <jean_francois_gagne@yahoo.com>; "bug-bash@gnu.org" 
<bug-bash@gnu.org>; "bash@packages.debian.org" <bash@packages.debian.org> 
Envoyé le : Dimanche 4 mars 2012 22h51
Objet : Re: Bash scripting and large files: input with the read builtin from a 
redirection gives unexpected result with files larger than 2GB.
 
Bob Proulx <bob@proulx.com> writes:

> Chet Ramey wrote:
>> Jean-François Gagné wrote:
>> > uname output: Linux xxxxxxxx 2.6.32-5-amd64 #1 SMP Tue Jun 14 09:42:28 UTC 
>> > 2011 x86_64 GNU/Linux
>> > Machine Type: x86_64-pc-linux-gnu
>>
>> Compile and run the attached program.  If it prints out `4', which it does
>> on all of the Debian systems I've tried, file offsets are limited to 32
>> bits, and accessing files greater than 2 GB is going to be unreliable.
>
> Apparently all of the Debian systems you have tried are 32-bits
> systems.  On the reporter's 64-bit amd64 system it will print out 8.

But it won't help if you don't use it.

diff --git a/lib/sh/zread.c b/lib/sh/zread.c
index 0fd1199..3731a41 100644
--- a/lib/sh/zread.c
+++ b/lib/sh/zread.c
@@ -161,7 +161,7 @@ zsyncfd (fd)
      int fd;
{
   off_t off;
-  int r;
+  off_t r;

   off = lused - lind;
   r = 0;

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."