QA·C Help - 2777

	2777	Apparent: Copy between overlapping objects.

Pointers

An apparent condition has been detected. Examination of the context indicates that an operation is being performed which will sometimes attempt to copy data between two objects which overlap in memory. The behavior will be undefined. It may be advisable to use the function 'memmove' instead.

For example, in the code below, the buffers addressed by pointers 'p1' and 'p2' will overlap if the value of the function parameter 'n' exceeds '3',


/*PRQA S 315,702,1253,2017,2211,3120,3132,3227,3408,3447 ++ */

#include <string.h>

extern int buf1[10];

extern void f2777(int p)
{
    int * p1;
    int * p2;
    unsigned int n = 1;

    p1 = buf1;
    p2 = &buf1[3];

    if (p > 0)
    {
        n = 5;
    }

    (void)memcpy (p1, p2, n * sizeof(int));      /* 2777 */
    (void)memmove(p1, p2, n * sizeof(int));      /*      */
}

See also:

2776 Definite: Copy between overlapping objects.
2778 Suspicious: Copy between overlapping objects.

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