bus_error.c

#include <fcntl.h> /* O_ constants */
#include <unistd.h> /* ftruncate */
#include <sys/mman.h> /* mmap */
#include <string.h>

int main() {
    int fd;
    char *map;
    char *name = "test.txt";

    fd = open(name, O_RDWR | O_CREAT | O_TRUNC, (mode_t)0600);
    posix_fallocate(fd, 0, 0);
    /* THIS is the cause of the problem. */
    /*ftruncate(fd, size);*/
    map = mmap(NULL, 4, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    /* This is what generates the SIGBUS. */
    *map = 0;

    munmap(map, 4);
    close(fd);
}