memcpy( ) behaviour on 11i HP-UX machine

[Puneet_1]

This is regarding the memcpy() function
used on HP-UX 11.11 machine. memcpy ()
takes 3 parameters. First two are
strings and third one is no. of bytes
to be copied. If we pass the third
argument a negative number I.e. number
of bytes to be copy is negative then it
works fine with HP-UX v10.2 and v11.0
but fails (give segmentation fault
core) on 11i HP-UX machine.

Why is this scenario?

[Adam J Markiewicz]

???

How would you define 'working fine while copying negative number of bytes'? This function should do something exept from returning without core.

Actually I belive that core gewnerating is 'working fine with such argument' (to be precise - I assume you're not trying to copy more that 2 GB of memory), so the previous behaviour is simply a bug.

Regards

Adam

[Puneet_1]

Actually the scenario is like this:

My program logic calls memcpy funtion:
call memcpy(char *str1, char *str2, int count);

As per the logic of the program this count equal to -1. Which logically should not be the case. But we diidn't come across any problem when we ran our program on HP-UX 10.2 and HP-UX 11.0. But hen we ported it to HP-UX 11.11, our program generated a core. On debugging we found out that actually program logic is trying to copy negative byte using memcpy and while doing so it is generating core.
Then we prepared a small program which simply uses memcpy function. We found out that in HP-UX 10.2 and HP-UX 11.0, whenever memcpy acounter its third argument negative it treats it as zero. But in 11.11 HP -UX it genrated segmentation fault core dump.

I want to know that is this a bug or is it an enhancement of HP-UX 11.11 machine.

Is there a patch available for this or do I have to provide a check before memcpy() function that throw an error when ever third argument (no. of bytes to cpopy) is negative.

Let me know in case of any doubts.

Thanks and regards.

[Adam J Markiewicz]

from /usr/inclue/string.h:
extern void *memcpy(void *, const void *, size_t);

from: /usr/include/sys/_size_t.h:
typedef unsigned long size_t;

If you are interested in how much bytes are you trying to copy use:
printf( "Number of bytes: %lu\n", (unsigned long) -1L );

Why did it work before? I don't know, but I think it shouldn't also.

Hope this exhaust your doubts. :)

Adam