strncpy behavious different under Linux and Solari

Unregistered · 07-24-2002

Dear all

I have the following code which is written in C and compiled
under gcc in both Linux and Solaris. However, it run differently
from the two platform.

In Linux, the gcc is 2.96 and the result is
Length = 8, value = YYYYMMDD
Length = 4, value = YYYY
Length = 4, value = MMDD
Length = 2, value = MM

In Solaris, the gcc verison is unknown to me and the result is
Length = 8, value = YYYYMMDD
Length = 4, value = YYYY
Length = 4, value = MMDD
Length = 4, value = MM

In Solaris, the code also seems to have memory overrun.

Can anyone help ?

#include <string.h>
#include <stdlib.h>

main(int argc, char **argv)
{
char *strTmp_1;
char *strTmp_2;
char *strTmp_3;

char strTmp[9] = "YYYYMMDD";

printf("%s%d%s%s\n", "Length = ", strlen(strTmp),
", value = ", strTmp);

strTmp_1 = (char*) malloc(strlen("YYYYY"));
strTmp_1 = strncpy(strTmp_1, strTmp, strlen("YYYY"));
printf("%s%d%s%s\n", "Length = ", strlen(strTmp_1),
", value = ", strTmp_1);

strcpy(strTmp, strTmp + strlen("YYYY"));
printf("%s%d%s%s\n", "Length = ", strlen(strTmp),
", value = ", strTmp);

strTmp_2 = (char*) malloc(strlen("MM") + strlen("\0"));
strTmp_2 = strcat((char *) memcpy(strTmp_2, strTmp,
strlen("MM")), "\0");
printf("%s%d%s%s\n", "Length = ", strlen(strTmp_2),
", value = ", strTmp_2);
}

**Hammer** · 07-25-2002

>strTmp_1 = strncpy(strTmp_1, strTmp, strlen("YYYY"));
The strTmp_1 isn't overflowing, it just isn't being NULL terminated. Look at this bit of info from the strncpy help page:

Code:

char *strncpy( char *dst,
               const char *src,
               size_t n );

If the string pointed to by src is shorter than n characters, null characters are appended to the copy in the array pointed to by dst, until n characters in all have been written. If the string pointed to by src is longer than n characters, then the result isn't terminated by a null character.

To null terminate the array, just to this:
>strTmp_1[4] = '\0';

Thread: strncpy behavious different under Linux and Solari

Thread Tools

Search Thread

Display

strncpy behavious different under Linux and Solari