1 files changed, 332 insertions, 2 deletions

diff --git a/src/userprog/syscall.c b/src/userprog/syscall.c
index 370c89b..c1308ca 100644
--- a/src/userprog/syscall.c
+++ b/src/userprog/syscall.c
@@ -4,6 +4,17 @@
 #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
@@ -13,8 +24,327 @@ syscall_init (void)
 }
 
 static void
-syscall_handler (struct intr_frame *f UNUSED) 
+halt (void)
+{
+  power_off();
+}
+
+static bool
+create (const char *filename, off_t initial_size)
+{
+  return filesys_create (filename, initial_size);
+}
+
+static bool
+remove (const char *filename)
+{
+  return filesys_remove (filename);
+}
+
+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)
 {
-  printf ("system call!\n");
+  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 int
+filesize (int fd_i)
+{
+  struct thread *thread = thread_current ();
+  struct file **fd = get_fd (thread, fd_i);
+  if (fd && *fd) {
+    return file_length (*fd);
+  }
+  return -1;
+}
+
+static void
+seek (int fd_i, unsigned position)
+{
+  struct thread *thread = thread_current ();
+  struct file **fd = get_fd (thread, fd_i);
+  if (fd && *fd) {
+    file_seek (*fd, position);
+  }
+}
+
+static unsigned
+tell (int fd_i)
+{
+  struct thread *thread = thread_current ();
+  struct file **fd = get_fd (thread, fd_i);
+  if (fd && *fd) {
+    return file_tell (*fd);
+  }
+  return 0;
+}
+
+
+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 *filename)
+{
+  return process_execute (filename);
+}
+
+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_PTR_AND_MAYBE_EXIT(PTR)  \
+  do {                                 \
+    if (!ptr_is_valid (PTR)) {         \
+      exit (-1);                       \
+      return;                          \
+    }                                  \
+  } while (0)
+
+
+static void
+syscall_handler (struct intr_frame *f UNUSED) 
+{
+  // check esp
+  int *syscall_number = INTR_ESP (0, int);
+
+  CHECK_PTR_AND_MAYBE_EXIT (syscall_number);
+
+  char **filename;
+  int *status, *fd_i;
+  off_t *initial_size;
+  tid_t *child_tid;
+  unsigned *size, *position;
+  void **buf;
+
+  switch (*syscall_number) {
+    case 0:
+      // halt
+      halt ();
+      break;
+    case 1:
+      // exit
+      status = INTR_ESP (1, int);
+      CHECK_PTR_AND_MAYBE_EXIT (status);
+      exit (*status);
+      break;
+    case 2:
+      // exec
+      filename = INTR_ESP (1, char *);
+      CHECK_PTR_AND_MAYBE_EXIT (filename);
+      CHECK_PTR_AND_MAYBE_EXIT (*filename);
+      f->eax = exec (*filename);
+      break;
+    case 3:
+      // wait
+      child_tid = INTR_ESP (1, tid_t);
+      CHECK_PTR_AND_MAYBE_EXIT (child_tid);
+      f->eax = wait (*child_tid);
+      break;
+    case 4:
+      // create
+      filename = INTR_ESP (1, char *);
+      initial_size = INTR_ESP (2, off_t);
+      CHECK_PTR_AND_MAYBE_EXIT (filename);
+      CHECK_PTR_AND_MAYBE_EXIT (*filename);
+      CHECK_PTR_AND_MAYBE_EXIT (initial_size);
+      f->eax = create (*filename, *initial_size);
+      break;
+    case 5:
+      // remove
+      filename = INTR_ESP (1, char *);
+      CHECK_PTR_AND_MAYBE_EXIT (filename);
+      CHECK_PTR_AND_MAYBE_EXIT (*filename);
+      f->eax = remove (*filename);
+      break;
+    case 6:
+      // open
+      filename = INTR_ESP (1, char *);
+      CHECK_PTR_AND_MAYBE_EXIT (filename);
+      CHECK_PTR_AND_MAYBE_EXIT (*filename);
+      f->eax = open (*filename);
+      break;
+    case 7:
+      // filesize
+      fd_i = INTR_ESP (1, int);
+      CHECK_PTR_AND_MAYBE_EXIT (fd_i);
+      f->eax = filesize (*fd_i);
+      break;
+    case 8:
+      // read
+      fd_i = INTR_ESP (1, int);
+      buf = INTR_ESP (2, void *);
+      size = INTR_ESP (3, unsigned);
+      CHECK_PTR_AND_MAYBE_EXIT (fd_i);
+      CHECK_PTR_AND_MAYBE_EXIT (buf);
+      CHECK_PTR_AND_MAYBE_EXIT (*buf);
+      CHECK_PTR_AND_MAYBE_EXIT (size);
+      CHECK_PTR_AND_MAYBE_EXIT (*buf + *size);
+      f->eax = read (*fd_i, *buf, *size);
+      break;
+    case 9:
+      // write
+      fd_i = INTR_ESP (1, int);
+      buf = INTR_ESP (2, void *);
+      size = INTR_ESP (3, unsigned);
+      CHECK_PTR_AND_MAYBE_EXIT (fd_i);
+      CHECK_PTR_AND_MAYBE_EXIT (buf);
+      CHECK_PTR_AND_MAYBE_EXIT (*buf);
+      CHECK_PTR_AND_MAYBE_EXIT (size);
+      CHECK_PTR_AND_MAYBE_EXIT (*buf + *size);
+      f->eax = write (*fd_i, *buf, *size);
+      break;
+    case 10:
+      // seek
+      fd_i = INTR_ESP (1, int);
+      position = INTR_ESP (2, unsigned);
+      CHECK_PTR_AND_MAYBE_EXIT (fd_i);
+      CHECK_PTR_AND_MAYBE_EXIT (position);
+      seek (*fd_i, *position);
+      break;
+    case 11:
+      // tell
+      fd_i = INTR_ESP (1, int);
+      CHECK_PTR_AND_MAYBE_EXIT (fd_i);
+      f->eax = tell (*fd_i);
+      break;
+    case 12:
+      // close
+      fd_i = INTR_ESP (1, int);
+      close (*fd_i);
+      break;
+    default:
+      printf ("kernel: unknown syscall '%d'\n", *syscall_number);
+      break;
+  }
+}
+
+#undef INTR_ESP