45 lines
1012 B
C
45 lines
1012 B
C
#include <sys/types.h>
|
|
#include <sys/fcntl.h>
|
|
#include <sys/mman.h>
|
|
#include <unistd.h>
|
|
|
|
int main(int argc, char** argv)
|
|
{
|
|
int fd, fd2;
|
|
caddr_t addr;
|
|
char zeros[4096];
|
|
char ones[200];
|
|
|
|
memset(zeros, 0, sizeof zeros);
|
|
memset(ones, 1, sizeof ones);
|
|
#if 0
|
|
unlink("test2.data");
|
|
fd = open("test2.data", O_RDWR|O_CREAT, 0666);
|
|
if (fd < 0)
|
|
err(1, "creating file");
|
|
if (write(fd, zeros, sizeof zeros) < 0)
|
|
err(1, "writing zeros");
|
|
close(fd);
|
|
#endif
|
|
|
|
fd = open("test2.data", O_RDWR);
|
|
if (fd < 0)
|
|
err(1, "opening file");
|
|
if (lseek(fd, 600, SEEK_SET) < 0)
|
|
err(1, "seeking");
|
|
|
|
if (write(fd, ones, sizeof ones) < 0)
|
|
err(1, "writing ones");
|
|
|
|
addr = mmap(0, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
|
|
if (addr == MAP_FAILED)
|
|
err(1, "mapping");
|
|
unlink("test2.scratch");
|
|
fd2 = open("test2.scratch", O_RDWR|O_CREAT, 0666);
|
|
if (fd2 < 0)
|
|
err(1, "creating scratch");
|
|
|
|
if (write(fd2, addr, 4096) < 0)
|
|
err(1, "writing scratch");
|
|
}
|