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

 /*
  * Copyright (c) 2008 Jakub Jermar
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * - Redistributions in binary form must reproduce the above copyright
  *   notice, this list of conditions and the following disclaimer in the
  *   documentation and/or other materials provided with the distribution.
  * - The name of the author may not be used to endorse or promote products
  *   derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /** @addtogroup fs
  * @{
  */
 /**
  * @file    fat_ops.c
  * @brief   Implementation of VFS operations for the FAT file system server.
  */
 #include "fat.h"
 #include "../../vfs/vfs.h"
 #include <libfs.h>
 #include <ipc/ipc.h>
 #include <async.h>
 #include <errno.h>
 #include <string.h>
 #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;
 #define FAT_NAME_LEN        8
 #define FAT_EXT_LEN     3
 #define FAT_PAD         ' '
 #define FAT_DENTRY_UNUSED   0x00
 #define FAT_DENTRY_E5_ESC   0x05
 #define FAT_DENTRY_DOT      0x2e
 #define FAT_DENTRY_ERASED   0xe5
 static void dentry_name_canonify(fat_dentry_t *d, char *buf)
+{
     int i;
     for (i = 0; i < FAT_NAME_LEN; i++) {
         if (d->name[i] == FAT_PAD) {
             buf++;
             break;
+        }
         if (d->name[i] == FAT_DENTRY_E5_ESC)
             *buf++ = 0xe5;
         else
             *buf++ = d->name[i];
+    }
     if (d->ext[0] != FAT_PAD)
         *buf++ = '.';
     for (i = 0; i < FAT_EXT_LEN; i++) {
         if (d->ext[i] == FAT_PAD) {
             *buf = '\0';
             return;
+        }
         if (d->ext[i] == FAT_DENTRY_E5_ESC)
             *buf++ = 0xe5;
         else
             *buf++ = d->ext[i];
+    }
+}
 /* TODO and also move somewhere else */
 typedef struct {
     void *data;
 } block_t;
 static block_t *block_get(dev_handle_t dev_handle, off_t offset)
+{
     return NULL;    /* TODO */
+}
 static block_t *fat_block_get(dev_handle_t dev_handle, fs_index_t index,
     off_t offset) {
     return NULL;    /* TODO */
+}
 static void block_put(block_t *block)
+{
     /* TODO */
+}
 static void fat_node_initialize(fat_node_t *node)
+{
     node->type = 0;
     node->index = 0;
     node->pindex = 0;
     node->dev_handle = 0;
     link_initialize(&node->fin_link);
     link_initialize(&node->ffn_link);
     node->size = 0;
     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) {
         /*
          * The in-core node was found in the hash table.
          */
         node = hash_table_get_instance(lnk, fat_node_t, fin_link);
         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;
         b = fat_block_get(parentp->dev_handle, parentp->index, i);
         if (!b)
             return NULL;
         dentries = (i == blocks - 1) ?
             parentp->size % sizeof(fat_dentry_t) :
             dps;
         for (j = 0; j < dentries; j++) {
             d = ((fat_dentry_t *)b->data) + j;
             if (d->attr & FAT_ATTR_VOLLABEL) {
                 /* volume label entry */
                 continue;
+            }
             if (d->name[0] == FAT_DENTRY_ERASED) {
                 /* not-currently-used entry */
                 continue;
+            }
             if (d->name[0] == FAT_DENTRY_UNUSED) {
                 /* never used entry */
                 block_put(b);
                 return NULL;
+            }
             if (d->name[0] == FAT_DENTRY_DOT) {
                 /*
                  * Most likely '.' or '..'.
                  * It cannot occur in a regular file name.
                  */
                 continue;
+            }
             dentry_name_canonify(d, name);
             if (strcmp(name, component) == 0) {
                 /* hit */
                 void *node = fat_node_get(parentp->dev_handle,
                     (fs_index_t)uint16_t_le2host(d->firstc),
                     parentp->index);
                 block_put(b);
                 return node;
+            }
+        }
         block_put(b);
+    }
     return NULL;
+}
 static fs_index_t fat_index_get(void *node)
+{
     fat_node_t *fnodep = (fat_node_t *)node;
     if (!fnodep)
         return 0;
     return fnodep->index;
+}
 static size_t fat_size_get(void *node)
+{
     return ((fat_node_t *)node)->size;
+}
 static unsigned fat_lnkcnt_get(void *node)
+{
     return ((fat_node_t *)node)->lnkcnt;
+}
 static bool fat_is_directory(void *node)
+{
     return ((fat_node_t *)node)->type == FAT_DIRECTORY;
+}
 static bool fat_is_file(void *node)
+{
     return ((fat_node_t *)node)->type == FAT_FILE;
+}
 /** libfs operations */
 libfs_ops_t fat_libfs_ops = {
     .match = fat_match,
     .node_get = fat_node_get,
     .create = NULL,
     .destroy = NULL,
     .link = NULL,
     .unlink = NULL,
     .index_get = fat_index_get,
     .size_get = fat_size_get,
     .lnkcnt_get = fat_lnkcnt_get,
     .has_children = NULL,
     .root_get = NULL,
     .plb_get_char = NULL,
     .is_directory = fat_is_directory,
     .is_file = fat_is_file
 };
 void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
+{
     libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
+}
 /**
  * @}
  */

Subversion Repositories HelenOS

(root)/branches/network/uspace/srv/fs/fat/fat_ops.c @ 4718 – Rev 2831 → 2843