// Allocate an open file.
int
open_alloc(struct Open **o)
{
int i, r;
// Find an available open-file table entry
for (i = 0; i < MAXOPEN; i++) {
switch (pageref(opentab[i].o_ff)) {
case 0:
//writef("^^^^^^^^^^^^^^^^ (u_int)opentab[i].o_ff: %x\n",(u_int)opentab[i].o_ff);
if ((r = syscall_mem_alloc(0, (u_int)opentab[i].o_ff,
PTE_V | PTE_R | PTE_LIBRARY)) < 0) {
return r;
}
case 1:
opentab[i].o_fileid += MAXOPEN;
*o = &opentab[i];
user_bzero((void *)opentab[i].o_ff, BY2PG);
return (*o)->o_fileid;
}
}
return -E_MAX_OPEN;
}
int
opencons(void)
{
int r;
struct Fd *fd;
if ((r = fd_alloc(&fd)) < 0)
return r;
if ((r = syscall_mem_alloc(0, (u_int)fd, PTE_V|PTE_R|PTE_LIBRARY)) < 0)
return r;
fd->fd_dev_id = devcons.dev_id;
fd->fd_omode = O_RDWR;
return fd2num(fd);
}
//
// Set the page fault handler function.
// If there isn't one yet, _pgfault_handler will be 0.
// The first time we register a handler, we need to
// allocate an exception stack and tell the kernel to
// call _asm_pgfault_handler on it.
//
void
set_pgfault_handler(void (*fn)(u_int va, u_int err))
{
int r;
if (__pgfault_handler == 0) {
// Your code here:
// map one page of exception stack with top at UXSTACKTOP
// register assembly handler and stack with operating system
if(syscall_mem_alloc(0, UXSTACKTOP - BY2PG, PTE_V|PTE_R)<0 || syscall_set_pgfault_handler(0, __asm_pgfault_handler, UXSTACKTOP)<0)
{
writef("cannot set pgfault handler\n");
return;
}
// panic("set_pgfault_handler not implemented");
}
// Save handler pointer for assembly to call.
__pgfault_handler = fn;
}