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Re: [Bug-tar] Tar short read
From: |
Andreas Dilger |
Subject: |
Re: [Bug-tar] Tar short read |
Date: |
Tue, 27 Sep 2011 14:48:08 -0600 |
On 2011-09-27, at 2:38 PM, Andreas Dilger wrote:
> On 2011-09-27, at 1:48 PM, Sergey Poznyakoff wrote:
>> Kevin Fox <address@hidden> ha escrit:
>>
>>> Thats not how I read that function:
>>> size_t safe_rw (int fd, void const *buf, size_t count)
>>> {
>>> enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 };
>>> for (;;)
>>> {
>>> ssize_t result = rw (fd, buf, count);
>>> if (0 <= result)
>>> return result;
>>>
>>> short read, return right away without looping. I don't believe tar
>>
>> You seem to confuse "short reads" with "interrupted reads". A "short
>> read" is when read returns less bytes than requested. No signals are
>> delivered it this case. An "interrupted read" occurs when a signal is
>> delivered while read is in progress. In that case read returns -1 and
>> sets errno to EINTR. That's exactly what this function is designed to
>> handle.
>
> In addition to Kevin's recent comments, I also noticed in the SUSv2
> description of read(2):
>
> http://pubs.opengroup.org/onlinepubs/007908799/xsh/read.html
>
> "If the value of nbyte is greater than {SSIZE_MAX}, the result
> is implementation-dependent."
>
> Attached is an (untested) patch for fixing these issues. Maybe
> Kevin can give this a spin?
My bad, attached is a better patch (still untested, but fixes a
thinko that I'd meant to fix before sending):
Cheers, Andreas
safe-short-read.diff
Description: Binary data
- Re: [Bug-tar] Tar short read, (continued)
- Re: [Bug-tar] Tar short read, Kevin Fox, 2011/09/26
- Re: [Bug-tar] Tar short read, Paul Eggert, 2011/09/26
- Re: [Bug-tar] Tar short read, Kevin Fox, 2011/09/27
- Re: [Bug-tar] Tar short read, Kevin Fox, 2011/09/27
- Re: [Bug-tar] Tar short read, Sergey Poznyakoff, 2011/09/27
- Re: [Bug-tar] Tar short read, Kevin Fox, 2011/09/27
- Re: [Bug-tar] Tar short read, Sergey Poznyakoff, 2011/09/27
- Re: [Bug-tar] Tar short read, Kevin Fox, 2011/09/27
- Re: [Bug-tar] Tar short read, Sergey Poznyakoff, 2011/09/27
- Re: [Bug-tar] Tar short read, Andreas Dilger, 2011/09/27
- Re: [Bug-tar] Tar short read,
Andreas Dilger <=
- Re: [Bug-tar] Tar short read, Kevin Fox, 2011/09/27
- Re: [Bug-tar] Tar short read, Paul Eggert, 2011/09/28
- Re: [Bug-tar] Tar short read, Andreas Dilger, 2011/09/28
- Re: [Bug-tar] Tar short read, Paul Eggert, 2011/09/28
- Re: [Bug-tar] Tar short read, Sergey Poznyakoff, 2011/09/27
- Re: [Bug-tar] Tar short read, Andreas Dilger, 2011/09/27
- Re: [Bug-tar] Tar short read, Chuck Swiger, 2011/09/27
- Re: [Bug-tar] Tar short read, Kevin Fox, 2011/09/27
- Re: [Bug-tar] Tar short read, Sergey Poznyakoff, 2011/09/27
- Re: [Bug-tar] Tar short read, Kevin Fox, 2011/09/27