mirror of
https://github.com/ioacademy-jikim/debugging
synced 2025-06-08 00:16:11 +00:00
59 lines
1.1 KiB
C
59 lines
1.1 KiB
C
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/* A small demo of providing descriptions of structured types in error
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messages. */
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/* Relevant compile flags are:
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-Wall -g -I$prefix/include/valgrind
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eg -Wall -g -I`pwd`/Inst/include/valgrind
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include "memcheck/memcheck.h"
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/* Cause memcheck to complain about the address "a" and so to print
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its best guess as to what "a" actually is. a must be
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addressible. */
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void croak ( void* aV )
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{
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char* a = (char*)aV;
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char* undefp = malloc(1);
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char saved = *a;
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assert(undefp);
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*a = *undefp;
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(void) VALGRIND_CHECK_MEM_IS_DEFINED(a, 1);
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*a = saved;
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free(undefp);
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}
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#include <stdio.h>
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#include <string.h>
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typedef struct { short c1; char* c2[3]; } XX;
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typedef
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struct _str { int bing; int bong; XX xyzzy[77]; }
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Str;
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__attribute__((noinline))
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int blah ( int x, int y )
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{
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Str a[10];
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memset(a, 0, sizeof(a));
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croak(1 + (char*)(&a[3].xyzzy[x*y].c1));
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croak( (char*)(&a[5].bong) );
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croak( 1 + (char*)(&a[3].xyzzy[x*y].c2[2]) );
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memset(a, 0, sizeof(a));
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return a[3].xyzzy[x*y].c1;
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}
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int main ( void )
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{
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printf("answer is %d\n", blah(3,7) );
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return 0;
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}
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