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#include "userprog/syscall.h"
#include <stdio.h>
#include <syscall-nr.h>
#include "threads/interrupt.h"
#include "threads/thread.h"
#include "devices/input.h"
#include "filesys/file.h"
#include "filesys/filesys.h"
#include "filesys/off_t.h"
#include "lib/pid_t.h"
#include "userprog/pagedir.h"
#include "userprog/process.h"
#include "threads/init.h"
#include "threads/malloc.h"
#include "threads/vaddr.h"
static void syscall_handler (struct intr_frame *);
void
syscall_init (void)
{
intr_register_int (0x30, 3, INTR_ON, syscall_handler, "syscall");
}
static void
halt (void)
{
power_off();
}
static bool
create (const char *filename, off_t initial_size)
{
return filesys_create (filename, initial_size);
}
static int
open (const char *filename)
{
struct thread *t = thread_current ();
if (!t->fds) {
t->fds = (struct file **) calloc (MAX_FDS, sizeof (struct file *));
}
struct file *file = filesys_open (filename);
if (!file) {
return -1;
}
for (int i = 0; i < MAX_FDS; i++) {
struct file **fd = t->fds + i;
if (*fd == NULL) {
*fd = file;
return i + 2; // 0 and 1 are reserved for stdin and stdout
}
}
free (file);
return -1;
}
static struct file **
get_fd (struct thread *thread, int fd_i)
{
if (!thread->fds) {
return NULL;
}
return thread->fds + fd_i - 2; // -2 since 0 and 1 are reserved and not present in the array
}
static void
exit (int status)
{
struct thread *thread = thread_current ();
if (thread->fds) {
for (int i = 0; i < MAX_FDS; i++) {
struct file **fd = thread->fds + i;
if (fd && *fd) {
file_close (*fd);
*fd = NULL;
}
}
free (thread->fds);
}
lock_acquire (&thread->parent->l);
thread->parent->exit_status = status;
lock_release (&thread->parent->l);
thread_exit ();
}
static int
wait (tid_t child_tid)
{
return process_wait (child_tid);
}
static int
read (int fd_i, void *buf, unsigned size)
{
struct thread *thread = thread_current ();
if (fd_i == 0) {
// stdin
unsigned i;
for (i = 0; i < size; i++) {
((char *)buf)[i] = input_getc ();
}
return i;
} else if (fd_i == 1) {
// can't read from stdout
return -1;
}
struct file **fd = get_fd (thread, fd_i);
if (fd && *fd) {
return file_read (*fd, buf, size);
} else {
return -1;
}
}
static int
write (int fd_i, const void *buf, unsigned size)
{
struct thread *thread = thread_current ();
if (fd_i == 1) {
// stdout
putbuf ((const char *)buf, size);
return size;
} else if (fd_i == 0) {
// can't write to stdout
return -1;
}
struct file **fd = get_fd (thread, fd_i);
if (fd && *fd) {
return file_write (*fd, buf, size);
} else {
return -1;
}
}
static void
close (int fd_i)
{
struct thread *thread = thread_current ();
struct file **fd = get_fd (thread, fd_i);
if (fd && *fd) {
file_close (*fd);
*fd = NULL;
}
}
static pid_t
exec (const char *file_name)
{
return process_execute (file_name);
}
static bool
ptr_is_valid (const void *ptr)
{
// uintptr_t ptr = _ptr;
if (!is_user_vaddr (ptr))
return false;
struct thread *t = thread_current ();
if (pagedir_get_page (t->pagedir, ptr) == NULL)
return false;
return true;
}
// cast argument N from f->esp to TYPE without dereferencing
#define INTR_ESP(N, TYPE) (TYPE *)(f->esp+(4*(N)))
#define CHECK_ESP_AND_MAYBE_EXIT(N) \
do { \
if (!ptr_is_valid ((f->esp+(4*(N))))) { \
exit (-1); \
return; \
} \
} while (0)
static void
syscall_handler (struct intr_frame *f UNUSED)
{
// check esp
CHECK_ESP_AND_MAYBE_EXIT (0);
int syscall_number = *INTR_ESP (0, int);
switch (syscall_number) {
case 0:
// halt
halt ();
break;
case 1:
// exit
exit (*INTR_ESP (1, int));
break;
case 2:
// exec
f->eax = exec (*INTR_ESP (1, char *));
break;
case 3:
// wait
f->eax = wait (*INTR_ESP (1, tid_t));
break;
case 4:
// create
f->eax = create (*INTR_ESP (1, char *), *INTR_ESP (2, off_t));
break;
case 6:
// open
f->eax = open (*INTR_ESP (1, char *));
break;
case 8:
// read
f->eax = read (*INTR_ESP (1, int), *INTR_ESP (2, void *), *INTR_ESP (3, unsigned));
break;
case 9:
// write
f->eax = write (*INTR_ESP (1, int), *INTR_ESP (2, const void *), *INTR_ESP (3, unsigned));
break;
case 12:
// close
close (*INTR_ESP (1, int));
break;
default:
printf ("kernel: unknown syscall '%d'\n", syscall_number);
break;
}
}
#undef INTR_ESP
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