static void
grow_stack()
{
int i, space[256];
for(i = 0; i < 256; i++) {
space[i] = 0;
}
if ((char *) &i > stack_lo_addr) {
grow_stack();
}
}
/* Reads 'size' bytes from file open as fd into buffer. Returns number of
bytes actually read - 0 at end of file, or -1 if file could not be read.
fd = 0 reads from the keyboard. */
static int
sys_read(int fd, void *buffer, unsigned size, struct intr_frame *f)
{
/* Cannot read from stdout. */
if (fd == STDOUT_FILENO)
sys_exit(ERROR);
int bytes;
void *buf_iter = pg_round_down(buffer);
check_fd(fd);
check_buffer(buffer, size);
lock_acquire(&secure_file);
for (; buf_iter <= buffer + size; buf_iter += PGSIZE) {
struct spt_entry *entry = get_spt_entry(&thread_current()->supp_pt, buf_iter);
if (entry == NULL && should_stack_grow(buf_iter, f->esp)) {
grow_stack(buf_iter);
}
}
/* fd = 0 corresponds to reading from stdin. */
if (fd == STDIN_FILENO)
{
unsigned i;
uint8_t keys[size];
/* Make an array of keys pressed. */
for (i = 0; i < size; i++)
{
keys[i] = input_getc();
}
/* Put these keys pressed into the buffer. */
memcpy(buffer, (const void *) keys, size);
/* Must have successfully read all bytes we were told to. */
bytes = size;
} else {
struct file *f = get_file(fd);
if (!f)
{
lock_release(&secure_file);
return ERROR;
}
bytes = file_read(f, buffer, size);
}
lock_release(&secure_file);
return bytes;
}
void ensure_stack(JVMState* jvms, uint stk_size) {
assert(verify_jvms(jvms), "jvms must match");
int grow_by = (int)stk_size - (int)jvms->stk_size();
if (grow_by > 0) grow_stack(jvms, grow_by);
}