Debugging Memory Heaps
Memory Management Functions
Managing Memory with Multiple Memory Heaps
Format
#include <string.h>
char *_debug_strcpy(char *string1, const char *string2,
const char *file, size_t line);
Language Level: Extension
_debug_strcpy 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 will report the file name file and line number line in a message.
Note: _debug_strcpy checks only the current default heap. Therefore, this debug support will not check all heaps within applications that have multiple user heaps.
To use _debug_strcpy, you must compile with the debug memory -qheapdebug compiler option. This option maps all strcpy calls to _debug_strcpy. You do not have to change your source code, in order for _debug_strcpy to verify the heap.
Note: The -qheapdebug option maps all calls to other string functions and all calls to memory management functions (including a heap-specific version), to their debug counterparts. To prevent a call from being mapped, parenthesize the function name.
Return Value
_debug_strcpy returns a pointer to the copied string string1.
Example
This example contains a programming error. The source string is
too long for the destination buffer, and the strcpy
operation damages the heap.
#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 should be 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 strcpy.c.
Heap state was valid at line 14 of strcpy.c.
Memory error detected at line 17 of strcpy.c.
****************************************************************************/
}
Debugging Memory Heaps
Memory Management Functions
Managing Memory with Multiple
Memory Heaps
Debugging Problems with Heap
Memory
-qheapdebug Compiler
Option
_debug_calloc - Allocate and Initialize
Memory
_debug_free - Free Allocated Memory
_debug_heapmin - Free Unused Memory in the
Default Heap
_debug_malloc - Allocate Memory
_debug_memcpy - Copy Bytes
_debug_memmove - Copy Bytes
_debug_memset - Set Bytes to Value
_debug_realloc - Reallocate Memory Block
_debug_strcat - Concatenate Strings
_debug_strncat - Concatenate Strings
_debug_strncpy - Copy Strings
_debug_strnset - Set Characters in String
_debug_strset - Set Characters in String
_debug_ucalloc - Reserve and Initialize
Memory from User Heap
_debug_uheapmin - Free Unused Memory in
User Heap
_debug_umalloc - Reserve Memory Block from
User Heap
