Re: Strcpy_s and strcpy
On Jul 2, 10:41 am, "Jim Langston" <tazmas...@rocketmail.com> wrote:
<Samant.Tru...@gmail.com> wrote in message
news:5f8b04b8-2b21-4fbd-903f-a5567072f16c@34g2000hsf.googlegroups.com...
I have changed my strcpy to strcpy_s for 2005 project. It's
fairly big project and was using strycpy lot of places. The
program started corrupting the stack and in turn crashing
the application. We have realized that it is due to
strcpy_s. We have changes that to strpcy and then it was
fine.
For the moment.
There are some places the destlength was more then whatever
size of deststr. I know it is a mistake but the copy string
had character to copy. So I was thinking it shouldn't crash
the project. Isn't that true?
Garbage in, garbage out. If you lie to the function, you can't
expect it to behave normally.
Example:
deststr[128];
copystr[] = "Test String";
destlength = 256;
strcpy_s(deststr, destlength, copystr);
even strcpy_s(deststr, strlen(copystr), copystr); was crashing (I need
to look more for this)
But is there any known problem with strcpy_s?
A test program shows that strcpy_s is doing some nasty
business at least in debug. Output of the following program
is:
XXXXXXXXXXX
58 58 58 58 58 58 58 58 58 58 58 0
Copy
43 6f 70 79 0 58 58 58 58 58 58 0
Copy
43 6f 70 79 0 fe fe fe fe fe fe fe
In Release it is differnent:
XXXXXXXXXXX
58 58 58 58 58 58 58 58 58 58 58 0
Copy
43 6f 70 79 0 58 58 58 58 58 58 0
Copy
43 6f 70 79 0 58 58 58 58 58 58 0
#include <iostream>
void ClearMemory( char* Memory, size_t Size )
{
memset( Memory, 'X', Size - 1 );
Memory[Size - 1] = '\0';
}
void DispMemory( char* Memory, size_t Size )
{
std::cout << Memory << "\n";
for ( size_t i = 0; i < Size; ++i )
std::cout << std::hex << (unsigned int)(unsigned char)Memory[i] <=
< "
";
std::cout << "\n";
}
int main()
{
char Buffer[12];
char String[] = "Copy";
ClearMemory( Buffer, sizeof( Buffer ) );
DispMemory( Buffer, sizeof( Buffer ) );
strcpy( Buffer, String );
DispMemory( Buffer, sizeof( Buffer ) );
ClearMemory( Buffer, sizeof( Buffer ) );
strcpy_s( Buffer, sizeof( Buffer ), String );
DispMemory( Buffer, sizeof( Buffer ) );
}
Looks fine to me. I'd consider this a feature, if it helps
detect errors like passing the wrong length.
--
James Kanze (GABI Software) email:james.kanze@gmail.com
Conseils en informatique orient=E9e objet/
Beratung in objektorientierter Datenverarbeitung
9 place S=E9mard, 78210 St.-Cyr-l'=C9cole, France, +33 (0)1 30 23 00 34