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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 "threads/init.h"
#include "threads/malloc.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) {
printf("[%s] open: allocating %d file descriptors\n", t->name, MAX_FDS);
t->fds = (struct fd *) calloc (MAX_FDS, sizeof (struct fd));
}
struct file *file = filesys_open(filename);
if (!file) {
printf("[%s] open: couldn't find file %s\n", t->name, filename);
return -1;
}
for (int i = 0; i < MAX_FDS; i++) {
struct fd *fd = t->fds + i;
if (!fd->active) {
fd->active = true;
fd->file = file;
return i + 2; // 0 and 1 are reserved for stdin and stdout
}
}
free(file);
printf("[%s] open: unable to find empty file descriptor\n", t->name);
return -1;
}
static struct fd *
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 struct file *
get_file (struct thread *thread, int fd_i)
{
struct fd *fd = get_fd(thread, fd_i);
if (!fd || !fd->active) {
printf("[%s] get_file: invalid file descriptor\n", thread->name);
return NULL;
}
return fd->file;
}
static void
exit (int status)
{
struct thread *thread = thread_current ();
if (thread->fds) {
for (int i = 0; i < MAX_FDS; i++) {
struct fd *fd = thread->fds + i;
if (fd && fd->active) {
file_close (fd->file);
fd->active = false;
}
}
free(thread->fds);
}
}
static int
read (int fd_i, void *buf, unsigned size)
{
struct thread *thread = thread_current ();
if (fd_i == 0) {
// stdin
int i;
for (i = 0; i < size; i++) {
((char *)buf)[i] = input_getc ();
}
return i;
} else if (fd_i == 1) {
// can't read from stdout
printf("[%s] read: tried to read from stdout\n", thread->name);
return -1;
}
struct file *file = get_file(thread, fd_i);
if (!file) {
return -1;
}
int n = file_read (file, buf, size);
printf("%d/%d: %s\n", n, size, (char *)buf);
return n;
}
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) {
printf ("[%s] write: tried to write to stdin\n", thread->name);
return -1;
}
struct file *file = get_file (thread, fd_i);
if (!file) {
return -1;
}
int n = file_write(file, buf, size);
printf ("%d/%d: %s\n", n, size, (char *)buf);
return n;
}
static void
close (int fd_i)
{
struct thread *thread = thread_current ();
struct fd *fd = get_fd(thread, fd_i);
if (!fd) {
return;
}
if (!fd->active) {
printf("[%s] close: tried to close inactive file descriptor %d\n", thread->name, fd_i);
return;
}
file_close (fd->file);
fd->active = false;
}
// cast to TYPE and deref argument N from f->esp
#define INTR_ESP(N, TYPE) *(TYPE *)(f->esp+(4*(N)))
static void
syscall_handler (struct intr_frame *f UNUSED)
{
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 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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