_debug_strcpy — Copy strings

Format

#include <string.h>
char *_debug_strcpy(char *string1, const char *string2, const char *file,
                    size_t line);

Purpose

This is the debug version of strcpy. Like strcpy, it copies string2, including the ending null character, to the location specified by string1.

_debug_strcpy validates the heap after copying the string to the target location, and performs this check only when the target is within a heap. _debug_strcpy makes an implicit call to _heap_check. If _debug_strcpy detects a corrupted heap when it makes a call to _heap_check, _debug_strcpy reports the file name file and line number line in a message.

Return values

Returns a pointer to the copied string string1.

Examples

This example contains a programming error. The source string is too long for the destination buffer, and the strcpy operation damages the heap.

/*  _debug_strcpy.c  */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#define  SIZE          10

int main(void)
{
   char *source = "1234567890123456789";
   char *destination;
   char *return_string;

   destination = (char*)malloc(SIZE);
   strcpy(destination, "abcdefg"),

   printf("destination is originally = '%s'\n", destination);
   return_string = strcpy(destination, source);
   printf("After strcpy, destination becomes '%s'\n\n", destination);
   return 0;
}

The output is similar to:

destination is originally = 'abcdefg'
End of allocated object 0x00073c80 was overwritten at 0x00073c8a.
The first eight bytes of the memory block (in hex) are: 3132333435363738.
This memory block was (re)allocated at line number 13 in _debug_strcpy.c.
Heap state was valid at line 14 of _debug_strcpy.c.
Memory error detected at line 17 of _debug_strcpy.c.