Below is a program which demonstrates the problem. On a Sparc 4,
the program exits immediately and 5 seconds later "Baz!" is printed.
On the Redhat 5.x systems I've been trying it on I only get the following:
fenris@cow:~[0]$ ./foo
mmap error! Invalid argument
I've tried various sizes (4096, 65536, 10, etc) but none seem to work.
Any suggestions?
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
int main(void)
{
int fd;
char *area;
fd = open("/dev/zero", O_RDWR);
if (fd < 0) {
printf("open error! %s\n", strerror(errno));
return -1;
}
area = mmap(NULL, 10, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (area == MAP_FAILED) {
printf("mmap error! %s\n", strerror(errno));
return -1;
}
close(fd);
if (fork()) {
strcpy(area, "Baz!\n");
_exit(0);
} else {
sleep(5);
printf("%s", area);
exit(0);
}
}
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