114 lines
2.1 KiB
C
114 lines
2.1 KiB
C
#include <stdio.h>
|
|
#include <unistd.h>
|
|
#include <sys/types.h>
|
|
#include <fcntl.h>
|
|
#include <sys/mman.h>
|
|
|
|
main()
|
|
{
|
|
int fd, r, w, l;
|
|
char buf[1024];
|
|
char *v;
|
|
|
|
fd = open("/dev/zero", O_RDONLY);
|
|
if (fd < 0)
|
|
{
|
|
fprintf(stderr, "Unable to open /dev/zero for reading\n");
|
|
perror("The error was");
|
|
exit(1);
|
|
}
|
|
|
|
l = read(fd, buf, 1024);
|
|
if (l != 1024)
|
|
{
|
|
fprintf(stderr, "Asked to read 1024 bytes, got %d\n", l);
|
|
exit(1);
|
|
}
|
|
|
|
for (r=0; r<1024; r++)
|
|
if (buf[r] != 0)
|
|
{
|
|
fprintf(stderr, "/dev/zero returned a byte of %02x at offset %d\n",
|
|
buf[r], r);
|
|
exit(1);
|
|
}
|
|
|
|
l = lseek(fd, 4096, 0);
|
|
if (l != 0)
|
|
{
|
|
fprintf(stderr, "l == %d\n", l);
|
|
exit(1);
|
|
}
|
|
|
|
l = close(fd);
|
|
if (l != 0)
|
|
{
|
|
fprintf(stderr, "close: returned %d\n", l);
|
|
perror("The error was");
|
|
exit(1);
|
|
}
|
|
|
|
fd = open("/dev/zero", O_WRONLY);
|
|
if (fd < 0)
|
|
{
|
|
fprintf(stderr, "Unable to open /dev/zero for writing\n");
|
|
perror("The error was");
|
|
exit(1);
|
|
}
|
|
|
|
l = write(fd, buf, 1024);
|
|
if (l != 1024)
|
|
{
|
|
fprintf(stderr, "Asked to write 1024 bytes, got %d\n", l);
|
|
exit(1);
|
|
}
|
|
|
|
l = close(fd);
|
|
if (l != 0)
|
|
{
|
|
fprintf(stderr, "close: returned %d\n", l);
|
|
perror("The error was");
|
|
exit(1);
|
|
}
|
|
|
|
fd = open("/dev/zero", O_RDWR);
|
|
v = (char *)mmap(0, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
|
|
if (v == (char *)-1)
|
|
{
|
|
fprintf(stderr, "mmap r/w /dev/zero failed\n");
|
|
perror("The error was");
|
|
exit(1);
|
|
}
|
|
|
|
for (r=0; r<65536; r++)
|
|
if (v[r] != 0)
|
|
{
|
|
fprintf(stderr, "mmap'd r/w /dev/zero has byte %d at offset %d\n",
|
|
v[r], r);
|
|
exit(1);
|
|
}
|
|
munmap(v, 65536);
|
|
close(fd);
|
|
|
|
fd = open("/dev/zero", O_RDONLY);
|
|
v = (char *)mmap(0, 65536, PROT_READ, MAP_SHARED, fd, 0);
|
|
if (v == (char *)-1)
|
|
{
|
|
fprintf(stderr, "mmap /dev/zero r/o failed\n");
|
|
perror("The error was");
|
|
exit(1);
|
|
}
|
|
|
|
for (r=0; r<65536; r++)
|
|
if (v[r] != 0)
|
|
{
|
|
fprintf(stderr, "mmap'd r/o /dev/zero has byte %d at offset %d\n",
|
|
v[r], r);
|
|
exit(1);
|
|
}
|
|
munmap(v, 65536);
|
|
close(fd);
|
|
|
|
exit(0);
|
|
}
|