16.7 Incompatible function calls

This example illustrates how the mpatrol library checks for calls to incompatible pairs of memory allocation functions. It requires the use of C++, although does not use any C++ features except for overloaded operators. The source is in `tests/fail/test7.c', and `tests/fail/test8.c' is similar.

23 /* 24 * Allocates a block of 16 bytes using C++ operator new[] and then 25 * attempts to free it using C++ operator delete. 26 */ 29 #include "mpatrol.h" 32 int main(void) 33 { 34 char *p; 36 p = new char[16]; 37 delete p; 38 return EXIT_SUCCESS; 39 }

The relevant parts of `mpatrol.log' are shown below.

ALLOC: operator new[] (74, 16 bytes, 4 bytes) [int main()|test7.c|36] 0x0804955D main+13 0x400DB9CB __libc_start_main+255 0x080494C1 _start+33 returns 0x08062FC0 FREE: operator delete (0x08062FC0) [int main()|test7.c|37] 0x0804956E main+30 0x400DB9CB __libc_start_main+255 0x080494C1 _start+33 ERROR: [INCOMP]: operator delete: 0x08062FC0 was allocated with operator new[] 0x08062FC0 (16 bytes) {operator new[]:74:0} [int main()|test7.c|36] 0x0804955D main+13 0x400DB9CB __libc_start_main+255 0x080494C1 _start+33

This shows a call to operator new[], closely followed by a call to operator delete. However, in C++ calls to operator new[] must be matched by calls to operator delete[] and not operator delete. Hence, the library reports this as an error and does not free the memory allocation.