QA·C Help - 2778

	2778	Suspicious: Copy between overlapping objects.

Pointers

Dataflow analysis has identified a code construct which is suspicious. Examination of the context indicates that an operation is being performed which could 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 f2778(int p)
{
    int * p1;
    int * p2;
    unsigned int n = 4;
    int i;

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

    for (i = 0; i < p; ++i)
    {
        --n;
    }

    (void)memcpy (p1, p2, n * sizeof(int));      /* 2778 */
    (void)memmove(p1, p2, n * sizeof(int));      /*      */
}

See also:

2776 Definite: Copy between overlapping objects.
2777 Apparent: Copy between overlapping objects.

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