1 2 /* A small demo of providing descriptions of structured types in error 3 messages. */ 4 5 /* Relevant compile flags are: 6 7 -Wall -g -I$prefix/include/valgrind 8 9 eg -Wall -g -I`pwd`/Inst/include/valgrind 10 */ 11 12 #include <stdio.h> 13 #include <stdlib.h> 14 #include <assert.h> 15 #include "memcheck/memcheck.h" 16 17 /* Cause memcheck to complain about the address "a" and so to print 18 its best guess as to what "a" actually is. a must be 19 addressible. */ 20 21 void croak ( void* aV ) 22 { 23 char* a = (char*)aV; 24 char* undefp = malloc(1); 25 char saved = *a; 26 assert(undefp); 27 *a = *undefp; 28 (void) VALGRIND_CHECK_MEM_IS_DEFINED(a, 1); 29 *a = saved; 30 free(undefp); 31 } 32 33 #include <stdio.h> 34 #include <string.h> 35 36 typedef struct { short c1; char* c2[3]; } XX; 37 38 typedef 39 struct _str { int bing; int bong; XX xyzzy[77]; } 40 Str; 41 42 __attribute__((noinline)) 43 int blah ( int x, int y ) 44 { 45 Str a[10]; 46 memset(a, 0, sizeof(a)); 47 croak(1 + (char*)(&a[3].xyzzy[x*y].c1)); 48 croak( (char*)(&a[5].bong) ); 49 croak( 1 + (char*)(&a[3].xyzzy[x*y].c2[2]) ); 50 memset(a, 0, sizeof(a)); 51 return a[3].xyzzy[x*y].c1; 52 } 53 54 int main ( void ) 55 { 56 printf("answer is %d\n", blah(3,7) ); 57 return 0; 58 } 59
