fix: extract supplemental and shared_files initialisation

src/vm/page.c

@@ -9,17 +9,29 @@
 #include "userprog/process.h"
 #include "vm/frame.h"
 
+static unsigned page_hash (const struct hash_elem *e, void *aux UNUSED);
+static bool page_less (const struct hash_elem *a_, const struct hash_elem *b_,
+                       void *aux UNUSED);
 static struct shared_page_entry *shared_page_insert (struct file *file,
                                                      void *upage, void *frame);
 static struct shared_file_entry *shared_file_get (struct file *file);
+static struct shared_page_entry *shared_page_get (struct file *file,
+                                                  void *upage);
 static unsigned shared_page_hash (const struct hash_elem *e, void *aux UNUSED);
 static bool shared_page_less (const struct hash_elem *a_,
                               const struct hash_elem *b_, void *aux UNUSED);
 
+/* Initialise a thread's supplemental pages table. */
+bool
+init_pages (struct thread *t)
+{
+  return hash_init (&t->pages, page_hash, page_less, NULL);
+}
+
 /* Hashing function needed for the SPT table. Returns a hash for an entry,
    based on its upage. */
 unsigned
-page_hash (const struct hash_elem *e, UNUSED void *aux)
+page_hash (const struct hash_elem *e, void *aux UNUSED)
 {
   struct page_entry *page = hash_entry (e, struct page_entry, elem);
   return hash_ptr(page->upage);
@@ -167,6 +179,15 @@ page_cleanup (struct hash_elem *e, void *aux UNUSED)
   free (page);
 }
 
+/* Initialise the shared files and table and lock. */
+bool
+shared_files_init ()
+{
+  lock_init (&shared_files_lock);
+  if (!hash_init (&shared_files, shared_file_hash, shared_file_less, NULL))
+    PANIC ("Failed to initialise shared_files table.");
+}
+
 /* Hashing function needed for the shared_file table. Returns a hash for an
    entry based on its file pointer. */
 unsigned