initial implementation of memory mapped files

1 files changed, 116 insertions, 0 deletions

diff --git a/vm/mmap.c b/vm/mmap.c
new file mode 100644
index 0000000..9e7ae47
--- /dev/null
+++ b/vm/mmap.c
@@ -0,0 +1,116 @@
+#include <string.h>
+#include "filesys/file.h"
+#include "threads/thread.h"
+#include "threads/vaddr.h"
+#include "threads/malloc.h"
+#include "threads/palloc.h"
+#include "vm/mmap.h"
+#include "vm/page.h"
+
+static struct mmap_table_entry *mmap_table_get (struct mmap_table *table,
+    mapid_t mapid);
+
+/* initialize memory mapped files table */
+bool
+mmap_table_init (struct mmap_table *table)
+{
+  table->ids = palloc_get_page (PAL_ZERO);
+  if (table->ids == NULL)
+    return false;
+  table->id_cap  = PGSIZE / sizeof (table->ids[0]);
+  table->id_free = 0;
+  table->id_max  = -1;
+  return true;
+}
+
+/* frees the content of mmap table */
+void
+mmap_table_free (struct mmap_table *table)
+{
+  //TODO
+  palloc_free_page (table->ids);
+}
+
+/* inserts a new mmap entry in the mmap table
+   returns -1 if entry is invalid or already in the table */
+mapid_t
+mmap_table_insert (struct mmap_table *table, void *addr, struct file *file,
+    off_t len)
+{
+  off_t ofs = 0;
+  size_t page_read_bytes;
+  struct mmap_table_entry *mme;
+  mapid_t mapid;
+
+  /* no more entries left */
+  if (table->id_free >= table->id_cap)
+    return -1;
+
+  mme = malloc (sizeof *mme);
+  if (mme == NULL)
+    return -1;
+
+  mapid = table->id_free++;
+  mme->addr  = addr;
+  mme->file  = file;
+  table->ids[mapid] = mme;
+
+  /* create needed pages in page table */
+  while (len > 0)
+    {
+      page_read_bytes = (len < PGSIZE) ? len : PGSIZE;
+
+      if (!page_table_insert_segment (&thread_current ()->page_table, file, ofs,
+            addr, page_read_bytes, true))
+        return -1;
+
+      /* Advance. */
+      len  -= PGSIZE;
+      ofs  += page_read_bytes;
+      addr += PGSIZE;
+    }
+
+  /* update index of free/max mapid index */
+  if (mapid > table->id_max)
+    table->id_max = mapid;
+  while (table->ids[table->id_free] != NULL)
+  {
+    table->id_free++;
+    if (table->id_free >= table->id_cap)
+      break;
+  }
+
+  return mapid;
+}
+
+static struct mmap_table_entry *
+mmap_table_get (struct mmap_table *table, mapid_t mapid)
+{
+  if (mapid < 0 || mapid >= table->id_cap || !table->ids[mapid])
+    return NULL;
+  return table->ids[mapid];
+}
+
+bool
+mmap_table_remove (struct mmap_table *table, mapid_t mapid)
+{
+  struct mmap_table_entry *mme = mmap_table_get(table, mapid);
+  if (mme == NULL)
+    return false;
+
+  table->ids[mapid] = NULL;
+
+  //TODO
+
+  /* update index of free/max file descriptor index */
+  if (mapid < table->id_free)
+    table->id_free = mapid;
+  while (table->ids[table->id_max] == NULL)
+  {
+    table->id_max--;
+    if (table->id_max < 0)
+      break;
+  }
+
+  return true;
+}