Dear folks, When we were trying to make a userland FS application we have encountered "Invalid Argument" when doing mmap() over an open descriptor to a disk device. The program goes here:
============================
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h> /* mmap() */
#include <fcntl.h>
#include <errno.h>
#include <assert.h>
int
main(int argc, char *argv[])
{
int fd;
char *src, *dst;
struct stat statbuf;
dst = strdup("abcdefghijklmn");
if (dst == NULL) {
printf("Can not allocate memory\n");
exit(-1);
}
if ((fd = open("/dev/da2s1", O_RDWR | O_DIRECT)) < 0)
printf("can't open for read/write");
if ((src = mmap(0, 10, PROT_WRITE | PROT_READ,
MAP_SHARED, fd, 0)) == (caddr_t) -1) {
perror("mmap error for input");
return -1;
}
memcpy(dst, src, 10); /* does the file copy */
exit(0);
}
============================
Do we need some special prerequisite before doing mmap()? According to
the vm_mmap.c it seems that we should map a DTYPE_VNODE object, which
looks somewhat confusing...
Thanks in advance!
Cheers,
--
Xin LI <delphij delphij net> http://www.delphij.net/
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