[Bug libc/2013] New: memccpy() gives inconsistent results on mmapped files

[Bug libc/2013] New: memccpy() gives inconsistent results on mmapped files

[tee at sgi dot com]

Glenn Fowler of ATT reported that memccpy() gives inconsistent results
on mmapped files.  This was reported to SGI, but the bug is ia64
generic, I get the same errors on a vanilla ia64 box.

Glenn's test case follows, it has been tweaked to add a PREFAULT
option.  Prefaulting the input file makes memccpy work.  The problem 
occurs on at least glibc 2.3.3, glibc 2.3.4 and glibc 2.3.5.

# for i in 1 257 513 1025;do cc -DNUM=$i testmemccpy.c; ./a.out; done
FAILED NUM 1 offset 0 size 64 no match
FAILED NUM 257 offset 16384 size 8
OLD xxxxxxxx
NEW xxxxxxxN
FAILED NUM 513 offset 32768 size 8
OLD xxxxxxxx
NEW xxxxxxxN
FAILED NUM 1025 offset 65536 size 8
OLD xxxxxxxx
NEW xxxxxxxN

# for i in 1 257 513 1025;do cc -DNUM=$i -DPREFAULT testmemccpy.c; ./a.out; done
No errors.

/*
 * the umpteenth linux ia64 memccpy indictment
 *
 * Glenn Fowler ATT
 *
 * creates/clobbers the file ./testmemccpy.dat
 *
 * fails with
 *
 *      -DNUM=1 
 *      -DNUM=257
 *      -DNUM=513
 *      -DNUM=1025
 *
 * works with -DOH and any -DNUM=n, n>0, n<memory-limit
 *
 * please eradicate the cute memccpy tricks
 * surely the processor is fast enough to minimize their impact
 *
 * Also works with -DPREFAULT - prefaulting the mmapped file gives the
 * correct results in memccpy.  
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>

#ifndef NUM
#define NUM 257
#endif

#if OH

#undef  memccpy
#define memccpy memccpy_that_works

void* memccpy(void* as1, const void* as2, int c, size_t n)
{
        char*           s1 = (char*)as1;
        const char*     s2 = (char*)as2;
        const char*     ep = s2 + n;

        while (s2 < ep)
                if ((*s1++ = *s2++) == c)
                        return s1;
        return 0;
}

#endif

static const char x[] =
"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxN";

int main()
{
        char*           b;
        char*           s;
        char*           e;
        char*           t;
        long            m;
        int             f;
        char            u[1024];

        if ((f = open("testmemccpy.dat", O_CREAT|O_RDWR|O_TRUNC, 0666)) < 0)
        {
                fprintf(stderr, "creat error\n");
                return 1;
        }
        for (m = 0; m < NUM; m++)
                if (write(f, x, sizeof(x)-1) != sizeof(x)-1)
                {
                        fprintf(stderr, "write error\n");
                        return 1;
                }
        if (lseek(f, (off_t)0, SEEK_SET))
        {
                fprintf(stderr, "seek error\n");
                return 1;
        }
        m *= (sizeof(x)-1);
        if (!(b = s = mmap((void*)0, m, PROT_READ|PROT_WRITE, MAP_PRIVATE, f,
(off_t)0)))
        {
                fprintf(stderr, "mmap error\n");
                return 1;
        }
#ifdef	PREFAULT
	for (s = b; s < b+m; s+=4096)
		f = *s;
	s = b;
#endif
        for (e = s + m; s < e && (t = memccpy(u, s, 'N', (e-s) > sizeof(u) ?
sizeof(u) : (e-s))); s += (t-u))
                if ((t-u) != (sizeof(x)-1) || memcmp(u, s, t-u))
                {
                        fprintf(stderr, "FAILED NUM %d offset %lu size %lu\n",
NUM, (unsigned long)(s-b), (unsigned long)(t-u));
                        fprintf(stderr, "OLD %-.*s\n", t-u, s);
                        fprintf(stderr, "NEW %-.*s\n", t-u, u);
                        return 1;
                }
        if (s < e)
        {
                fprintf(stderr, "FAILED NUM %d offset %lu size %lu no match\n",
NUM, (unsigned long)(s-b), (unsigned long)(e-s));
                return 1;
        }
        return 0;
}

-- 
           Summary: memccpy() gives inconsistent results on mmapped files
           Product: glibc
           Version: 2.3.5
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: tee at sgi dot com
                CC: glibc-bugs at sources dot redhat dot com
 GCC build triplet: ia64-*-linux
  GCC host triplet: ia64-*-linux
GCC target triplet: ia64-*-linux


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[Bug libc/2013] memccpy() gives inconsistent results on mmapped files

[hjl at lucon dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hjl at lucon dot org


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[Bug libc/2013] memccpy() gives inconsistent results on mmapped files

[hjl at lucon dot org]

------- Additional Comments From hjl at lucon dot org  2005-12-29 16:51 -------
Doesn't SGI have a fix

http://www.gelato.unsw.edu.au/archives/linux-ia64/0412/11984.html

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[Bug libc/2013] memccpy() gives inconsistent results on mmapped files

[tee at sgi dot com]

------- Additional Comments From tee at sgi dot com  2006-01-02 21:31 -------
No, I'm afraid not.  We thought this looked like something Jes Sorensen had fixed previously, but we 
verified that his fix was in, and we can still reproduce it.  So this appears to be a different bug.

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[Bug libc/2013] memccpy() gives inconsistent results on mmapped files

[hjl at lucon dot org]

------- Additional Comments From hjl at lucon dot org  2006-01-05 22:55 -------
A patch is posted at

http://sources.redhat.com/ml/libc-alpha/2006-01/msg00048.html

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[Bug libc/2013] memccpy() gives inconsistent results on mmapped files

[tee at sgi dot com]

------- Additional Comments From tee at sgi dot com  2006-02-23 19:51 -------
The patch from Comment #3 does fix the problem for us.

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[Bug libc/2013] memccpy() gives inconsistent results on mmapped files

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2006-03-02 04:49 -------
Subject: Bug 2013

CVSROOT:	/cvs/glibc
Module name:	libc
Changes by:	roland@sources.redhat.com	2006-03-02 04:49:27

Modified files:
	sysdeps/ia64   : memccpy.S 

Log message:
	2006-01-05  H.J. Lu  <hongjiu.lu@intel.com>
	
	[BZ #2013]
	* sysdeps/ia64/memccpy.S: Properly handle recovery for
	predicated speculative load.

Patches:
http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/sysdeps/ia64/memccpy.S.diff?cvsroot=glibc&r1=1.7&r2=1.8



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[Bug libc/2013] memccpy() gives inconsistent results on mmapped files

[roland at gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|drepper at redhat dot com   |roland at gnu dot org


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[Bug libc/2013] memccpy() gives inconsistent results on mmapped files

[roland at gnu dot org]

------- Additional Comments From roland at gnu dot org  2006-03-02 04:50 -------
I put this on the trunk.  It seem right for 2.3 too.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
OtherBugsDependingO|                            |2123
              nThis|                            |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|0000-00-00 00:00:00         |2006-03-02 04:50:17
               date|                            |
   Target Milestone|---                         |2.3.7


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[Bug libc/2013] memccpy() gives inconsistent results on mmapped files

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2007-02-18 04:46 -------
The 2.3 is outdated.  Closing.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


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