memcheck/tests/linux/brk.c

   1 #include <assert.h>
   2 #include <stdio.h>
   3 #include <sys/syscall.h>
   4 #include <sys/types.h>
   5 #include <unistd.h>
   6
   7 // kernel brk() and libc brk() act quite differently...
   8
   9 int main(void)
  10 {
  11    int i;
  12    void* orig_ds = sbrk(0);
  13    void* ds = orig_ds;
  14    void* vals[10];
  15    void* res __attribute__((unused));
  16 #define EOL ((void*)( ~(long)0 ))
  17    vals[0] = (void*)0;
  18    vals[1] = (void*)1;
  19    vals[2] = ds - 0x1;          // small shrink
  20    vals[3] = ds;
  21    vals[4] = ds + 0x1000;       // small growth
  22    vals[5] = ds + 0x40000000;   // too-big growth
  23    vals[6] = ds + 0x500;        // shrink a little, but still above start size
  24    vals[7] = ds - 0x1;          // shrink below start size
  25 //   vals[8] = ds - 0x1000;       // shrink a lot below start size (into text)
  26 //   vals[9] = EOL;
  27    vals[8] = EOL;
  28
  29    for (i = 0; EOL != vals[i]; i++) {
  30       res = (void*)syscall(__NR_brk, vals[i]);
  31    }
  32
  33    assert( 0 == brk(orig_ds) );  // libc brk()
  34
  35    for (i = 0; EOL != vals[i]; i++) {
  36       res = (void*)(long)brk(vals[i]);
  37    }
  38
  39    return 0;
  40 }