WebSVN – HelenOS – Diff – /trunk/uspace/srv/fs/fat/fat_ops.c

 #include <byteorder.h>
 #include <libadt/hash_table.h>
 #include <libadt/list.h>
 #include <assert.h>
+#define BS_BLOCK        0
+#define FIN_KEY_DEV_HANDLE  0
+#define FIN_KEY_INDEX       1
 /** Hash table of FAT in-core nodes. */
 hash_table_t fin_hash;
 /** List of free FAT in-core nodes. */
 link_t ffn_head;
     node->lnkcnt = 0;
     node->refcnt = 0;
     node->dirty = false;
+}
+static uint16_t fat_bps_get(dev_handle_t dev_handle)
+{
+    block_t *bb;
+    uint16_t bps;
+    bb = block_get(dev_handle, BS_BLOCK);
+    assert(bb != NULL);
+    bps = uint16_t_le2host(((fat_bs_t *)bb->data)->bps);
+    block_put(bb);
+    return bps;
+}
 static void fat_sync_node(fat_node_t *node)
+{
     /* TODO */
+}
+/** Instantiate a FAT in-core node.
+ *
+ * FAT stores the info necessary for instantiation of a node in the parent of
+ * that node.  This design necessitated the addition of the parent node index
+ * parameter to this otherwise generic libfs API.
+ */
 static void *
 fat_node_get(dev_handle_t dev_handle, fs_index_t index, fs_index_t pindex)
+{
     link_t *lnk;
     fat_node_t *node = NULL;
-    block_t *bb;
     block_t *b;
+    unsigned bps;
+    unsigned dps;
     fat_dentry_t *d;
-    unsigned bps;       /* bytes per sector */
+    unsigned i, j;
-    unsigned dps;       /* dentries per sector */
     unsigned long key[] = {
-        dev_handle,
+        [FIN_KEY_DEV_HANDLE] = dev_handle,
-        index
+        [FIN_KEY_INDEX] = index
     };
     lnk = hash_table_find(&fin_hash, key);
     if (lnk) {
         /*
         if (!node->refcnt++)
             list_remove(&node->ffn_link);
         return (void *) node;
+    }
+    bps = fat_bps_get(dev_handle);
+    dps = bps / sizeof(fat_dentry_t);
     if (!list_empty(&ffn_head)) {
         /*
          * We are going to reuse a node from the free list.
          */
         lnk = ffn_head.next;
         list_remove(lnk);
         node = list_get_instance(lnk, fat_node_t, ffn_link);
         assert(!node->refcnt);
         if (node->dirty)
             fat_sync_node(node);
+        key[FIN_KEY_DEV_HANDLE] = node->dev_handle;
+        key[FIN_KEY_INDEX] = node->index;
+        hash_table_remove(&fin_hash, key, sizeof(key)/sizeof(*key));
     } else {
         /*
          * We need to allocate a new node.
          */
         node = malloc(sizeof(fat_node_t));
         if (!node)
             return NULL;
+    }
     fat_node_initialize(node);
+    node->refcnt++;
+    node->lnkcnt++;
+    node->dev_handle = dev_handle;
+    node->index = index;
+    node->pindex = pindex;
+    /*
+     * Because of the design of the FAT file system, we have no clue about
+     * how big (i.e. how many directory entries it contains) is the parent
+     * of the node we are trying to instantiate.  However, we know that it
+     * must contain a directory entry for our node of interest.  We simply
+     * scan the parent until we find it.
+     */
+    for (i = 0; ; i++) {
+        b = fat_block_get(node->dev_handle, node->pindex, i);
-    if (!pindex) {
+        if (!b) {
+            node->refcnt--;
+            list_append(&node->ffn_link, &ffn_head);
+            return NULL;
+        }
+        for (j = 0; j < dps; j++) {
+            d = ((fat_dentry_t *)b->data) + j;
+            if (d->firstc == node->index)
-    } else {
+                goto found;
+        }
+        block_put(b);
+    }
+found:
+    if (!(d->attr & (FAT_ATTR_SUBDIR | FAT_ATTR_VOLLABEL)))
+        node->type = FAT_FILE;
+    if ((d->attr & FAT_ATTR_SUBDIR) || !pindex)
+        node->type = FAT_DIRECTORY;
+    assert((node->type == FAT_FILE) || (node->type == FAT_DIRECTORY));
+    node->size = uint32_t_le2host(d->size);
+    block_put(b);
+    key[FIN_KEY_DEV_HANDLE] = node->dev_handle;
+    key[FIN_KEY_INDEX] = node->index;
+    hash_table_insert(&fin_hash, key, &node->fin_link);
+    return node;
+}
-#define BS_BLOCK    0
 static void *fat_match(void *prnt, const char *component)
+{
     fat_node_t *parentp = (fat_node_t *)prnt;
     char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
     unsigned i, j;
     unsigned bps;       /* bytes per sector */
     unsigned dps;       /* dentries per sector */
     unsigned blocks;
     fat_dentry_t *d;
-    block_t *bb;
     block_t *b;
-    bb = block_get(parentp->dev_handle, BS_BLOCK);
+    bps = fat_bps_get(parentp->dev_handle);
-    if (!bb)
-        return NULL;
-    bps = uint16_t_le2host(((fat_bs_t *)bb->data)->bps);
-    block_put(bb);
     dps = bps / sizeof(fat_dentry_t);
     blocks = parentp->size / bps + (parentp->size % bps != 0);
     for (i = 0; i < blocks; i++) {
         unsigned dentries;

Subversion Repositories HelenOS

(root)/trunk/uspace/srv/fs/fat/fat_ops.c @ 4680 – Rev 2831 → 2843