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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
static void check(const char* name, int ok)
{
printf("%s%s\n", ok ? "ok " : "FAIL ", name);
}
int main(void)
{
long start = (long)sbrk(0);
printf("heap base: %ld\n", start);
// obese alloc test
char* run[80];
for (int i = 0; i < 80; i++)
run[i] = malloc(4000);
long run_after = (long)sbrk(0);
for (int i = 0; i < 80; i++)
free(run[i]);
char* merged = malloc(80 * 4000 - 8000);
long merge_after = (long)sbrk(0);
check("freed neighbours coalesce", merged != 0 && merge_after <= run_after);
free(merged);
// a pile of small tagged allocations
char* blocks[16];
for (int i = 0; i < 16; i++)
{
blocks[i] = malloc(64);
for (int j = 0; j < 64; j++)
blocks[i][j] = (char)(i * 7 + j);
}
int small_ok = 1;
for (int i = 0; i < 16; i++)
for (int j = 0; j < 64; j++)
if (blocks[i][j] != (char)(i * 7 + j))
small_ok = 0;
check("small allocs keep their data", small_ok);
// a big block spanning several pages written edge to edge
unsigned long big = 20000;
unsigned char* buffer = malloc(big);
for (unsigned long k = 0; k < big; k++)
buffer[k] = (unsigned char)(k & 0xff);
int big_ok = 1;
for (unsigned long k = 0; k < big; k++)
if (buffer[k] != (unsigned char)(k & 0xff))
big_ok = 0;
check("big multi page alloc", big_ok);
// testing that the heap doesnt grow across the loop
long churn_before = (long)sbrk(0);
for (int i = 0; i < 2000; i++)
{
void* pointer = malloc(500);
free(pointer);
}
long churn_after = (long)sbrk(0);
check("alloc/free churn reclaims (no growth)", churn_before == churn_after);
// calloc dirty test
unsigned char* zeroed = calloc(200, 1);
int zero_ok = 1;
for (int i = 0; i < 200; i++)
if (zeroed[i] != 0)
zero_ok = 0;
check("calloc is zeroed", zero_ok);
// realloc test
char* grown = malloc(32);
for (int i = 0; i < 32; i++)
grown[i] = (char)(i + 1);
grown = realloc(grown, 500);
int grow_ok = 1;
for (int i = 0; i < 32; i++)
if (grown[i] != (char)(i + 1))
grow_ok = 0;
check("realloc grows and preserves data", grow_ok);
long end = (long)sbrk(0);
printf("heap high water: %ld bytes\n", end - start);
return 0;
}
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