Bug#658639: kfreebsd-9: 'write' system call violates POSIX standard

[Nicolas Bourdaud]

Sorry for replying so late

On 08/02/2012 06:58, Benjamin Kaduk wrote:
 Perhaps freebsd-standa...@freebsd.org would be
 appropriate for this?  Though perhaps -hackers would reach a larger
 audience.

I have dropped an email today in freebsd-standa...@freebsd.org:
http://lists.freebsd.org/pipermail/freebsd-standards/2012-February/002348.html

I hope it will attract enough attention.

Cheers,

Nicolas




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Bug#658639: kfreebsd-9: 'write' system call violates POSIX standard

[Robert Millan]

forwarded 658639 http://www.freebsd.org/cgi/query-pr.cgi?pr=164793
thanks

2012/2/5, Nicolas Bourdaud nicolas.bourd...@gmail.com:
 Bug report opened upstream:
 http://www.freebsd.org/cgi/query-pr.cgi?pr=164793

Thanks!

-- 
Robert Millan



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Processed: Re: Bug#658639: kfreebsd-9: 'write' system call violates POSIX standard

[Debian Bug Tracking System]

Processing commands for cont...@bugs.debian.org:

 forwarded 658639 http://www.freebsd.org/cgi/query-pr.cgi?pr=164793
Bug #658639 [src:kfreebsd-9] kfreebsd-9: 'write' system call violates POSIX 
standard
Set Bug forwarded-to-address to 
'http://www.freebsd.org/cgi/query-pr.cgi?pr=164793'.
 thanks
Stopping processing here.

Please contact me if you need assistance.
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658639: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=658639
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Bug#658639: kfreebsd-9: 'write' system call violates POSIX standard

[Nicolas Bourdaud]

On 04/02/2012 21:07, Robert Millan wrote:
 Can you reproduce this with upstream kernel? (apt-get install
 kfreebsd-downloader)

Yes it is reproducible with upstream kernel

 If it affects upstream, for this kind of reports it's much better to
 report them to FreeBSD PR database instead:
 
 http://www.freebsd.org/send-pr.html

Bug report opened upstream:
http://www.freebsd.org/cgi/query-pr.cgi?pr=164793

Cheers,

Nicolass




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Bug#658639: kfreebsd-9: 'write' system call violates POSIX standard

[Nicolas Bourdaud]

Source: kfreebsd-9
Severity: important
Tags: upstream

When a write() cannot transfer as many bytes as requested (because of a file
limit), it fails instead of transferring as many bytes as there is room to
write.

This is a violation of the POSIX standard:
http://pubs.opengroup.org/onlinepubs/007904975/functions/write.html

fsize-lim.c (attached) illustrates the problem. With a freebsd kernel, the
output is:
failed when adding 27 bytes after 59994 bytes (error: File too large)

The expected output (like with a linux kernel) should be:
added 6 bytes instead of 27 bytes after 59994 bytes
failed when adding 27 bytes after 6 bytes (error: File too large)


-- System Information:
Debian Release: wheezy/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: kfreebsd-amd64 (x86_64)

Kernel: kFreeBSD 9.0-1-amd64
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/dash
#include unistd.h
#include sys/time.h
#include sys/resource.h
#include stdio.h
#include sys/types.h
#include sys/stat.h
#include fcntl.h
#include signal.h
#include errno.h
#include string.h

#define TARGETSIZE	8
#define LIMSIZE		6
#define PATTSIZE	27


int main(void)
{
	struct rlimit lim;
	int fd;
	ssize_t retc;
	size_t count = 0;
	const char pattern[PATTSIZE] = Hello world!;
	
	signal(SIGXFSZ, SIG_IGN);
	lim.rlim_cur = LIMSIZE; 
	setrlimit(RLIMIT_FSIZE, lim);

	fd = open(result.txt, O_WRONLY|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR);

	while (count  TARGETSIZE) {
		retc = write(fd, pattern, PATTSIZE);

		if (retc  PATTSIZE  retc  0)
			fprintf(stderr,
			added %zi bytes instead of %u bytes after %zu bytes\n,
retc, PATTSIZE, count);
		else if (retc  0) {
			fprintf(stderr,
			failed when adding %u bytes after %zu bytes (error: %s)\n,
PATTSIZE, count, strerror(errno));
			break;
		}
		count += retc;
	}

	close(fd);

	return 0;
}

Bug#658639: kfreebsd-9: 'write' system call violates POSIX standard

[Robert Millan]

Hi Nicolas,

El 4 de febrer de 2012 20:49, Nicolas Bourdaud
nicolas.bourd...@gmail.com ha escrit:
 When a write() cannot transfer as many bytes as requested (because of a file
 limit), it fails instead of transferring as many bytes as there is room to
 write.

 This is a violation of the POSIX standard:
 http://pubs.opengroup.org/onlinepubs/007904975/functions/write.html

Can you reproduce this with upstream kernel? (apt-get install
kfreebsd-downloader)

If it affects upstream, for this kind of reports it's much better to
report them to FreeBSD PR database instead:

http://www.freebsd.org/send-pr.html

-- 
Robert Millan



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