Program to leak shared memory on OS X

mem-leaker.c

#include <stdio.h>
#include <sys/mman.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

int main()
{
    int err = 0;
    const size_t size = 100 * 1024 * 1024;
    char *shm_name = NULL;

    asprintf(&shm_name, "shm-foo-%d", getpid());
    printf("shm name: '%s'\n", shm_name);

    int fd = shm_open(shm_name, O_CREAT | O_RDWR, 0644);
    if (fd < 0) {
        perror("shm_open");
        return 1;
    }

    err = shm_unlink(shm_name);
    if (err) {
        perror("shm_unlink");
        return 1;
    }

    err = ftruncate(fd, size);
    if (err) {
        perror("ftruncate");
        return 1;
    }

    char *mem = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0);
    if (MAP_FAILED == mem) {
        perror("mmap");
        close(fd);
        return 1;
    }

    if ('A' == *mem) {
        printf("FILLED\n");
    } else {
        printf("not filled (%c)\n", *mem);
    }

    memset(mem, 'A', size);

    pid_t pid = fork();
    if (pid > 0) {
        /* parent */
    } else if (0 == pid) {
        /* child */
        sleep(10);

        err = close(fd);
        if (err) {
            perror("close child");
            return 1;
        }

        err = munmap(mem, size);
        if (err) {
            perror("munmap child");
            return 1;
        }

        printf("should be freed now\n");
        return 0;
    } else {
        perror("fork");
        return 1;
    }

    err = close(fd);
    if (err) {
        perror("close");
        return 1;
    }

    err = munmap(mem, size);
    if (err) {
        perror("munmap");
        close(fd);
        return 1;
    }

    return 0;
}