From: Albert Cahalan <albert@users.sf.net>
To: linux-kernel mailing list <linux-kernel@vger.kernel.org>
Cc: bernd@firmix.at, Anthony.Truong@mascorp.com,
alan@lxorguk.ukuu.org.uk, schwab@suse.de,
ysato@users.sourceforge.jp, willy@w.ods.org,
Valdis.Kletnieks@vt.edu, william.gallafent@virgin.net
Subject: Re: generic strncpy - off-by-one error
Date: 12 Aug 2003 22:18:21 -0400 [thread overview]
Message-ID: <1060741101.948.245.camel@cube> (raw)
You're all wrong. This is some kind of programming
test for sure!
Let us imagine that glibc has a correct version.
By exhaustive testing, I found a version that works.
Here it is, along with the test code:
//////////////////////////////////////////////////////
#define _GNU_SOURCE
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
// first correct implementation!
char * strncpy_good(char *dest, const char *src, size_t count){
char *tmp = dest;
memset(dest,'\0',count);
while (count-- && (*tmp++ = *src++))
;
return dest;
}
static char ref[32];
static char hmm[32];
static char s0[] = "";
static char s1[] = "1";
static char s2[] = "12";
static char s6[] = "123456";
static char s7[] = "1234567";
static char s8[] = "12345678";
static char s9[] = "123456789";
static void tester(const char *src, size_t count){
memset(ref,'%',sizeof ref);
memset(hmm,'%',sizeof hmm);
strncpy (ref+2,src,count);
strncpy_good(hmm+2,src,count);
if(memcmp(ref,hmm,sizeof hmm)){
printf("error @ size %d\n",(int)count);
}
}
int main(int argc, char *argv[]){
int i = 15;
while(i--){
tester(s0,i);
tester(s1,i);
tester(s2,i);
tester(s6,i);
tester(s7,i);
tester(s8,i);
tester(s9,i);
}
return 0;
}
////////////////////////////////////////////////////////////
next reply other threads:[~2003-08-13 2:28 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-13 2:18 Albert Cahalan [this message]
2003-08-13 2:47 ` generic strncpy - off-by-one error Erik Andersen
2003-08-13 3:38 ` Albert Cahalan
2003-08-13 3:56 ` Nick Piggin
2003-08-13 5:18 ` Willy Tarreau
2003-08-13 19:03 ` Timothy Miller
-- strict thread matches above, loose matches on Subject: below --
2003-08-20 7:43 Peter Kjellerstedt
2003-08-16 21:10 Peter Kjellerstedt
2003-08-18 18:41 ` Timothy Miller
2003-08-16 20:08 Peter Kjellerstedt
2003-08-16 9:19 Peter Kjellerstedt
2003-08-16 10:04 ` Daniel Forrest
2003-08-18 16:40 ` Timothy Miller
2003-08-16 8:15 Peter Kjellerstedt
2003-08-16 8:41 ` Daniel Forrest
2003-08-18 16:17 ` Timothy Miller
2003-08-18 16:06 ` Timothy Miller
2003-08-15 9:54 Peter Kjellerstedt
2003-08-15 17:52 ` Timothy Miller
2003-08-15 9:53 Peter Kjellerstedt
2003-08-15 17:47 ` Timothy Miller
2003-08-14 9:34 Peter Kjellerstedt
2003-08-14 19:45 ` Willy Tarreau
2003-08-14 20:24 ` Timothy Miller
2003-08-13 3:09 Anthony Truong
2003-08-12 14:07 Yoshinori Sato
2003-08-12 14:39 ` Willy Tarreau
2003-08-12 14:50 ` Yoshinori Sato
2003-08-12 15:03 ` Valdis.Kletnieks
2003-08-12 15:54 ` William Gallafent
2003-08-12 16:19 ` Valdis.Kletnieks
2003-08-12 16:09 ` Andreas Schwab
2003-08-12 1:56 Anthony Truong
2003-08-12 17:14 ` Alan Cox
2003-08-12 21:53 ` Bernd Petrovitsch
2003-08-12 1:28 Anthony Truong
2003-08-12 16:24 ` Bernd Petrovitsch
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