Changes in uspace/srv/fs/fat/fat_ops.c [dfddfcd:2ffaab5] in mainline

File:

• uspace/srv/fs/fat/fat_ops.c (modified) (9 diffs)

uspace/srv/fs/fat/fat_ops.c

@@ -52 +52 @@
 #include <adt/list.h>
 #include <assert.h>
-#include <fibril_sync.h>
+#include <fibril_synch.h>
 #include <sys/mman.h>
 #include <align.h>
@@ -71 +71 @@
 static int fat_match(fs_node_t **, fs_node_t *, const char *);
 static int fat_node_get(fs_node_t **, dev_handle_t, fs_index_t);
+static int fat_node_open(fs_node_t *);
 static int fat_node_put(fs_node_t *);
 static int fat_create_node(fs_node_t **, dev_handle_t, int);
@@ -83 +84 @@
 static bool fat_is_directory(fs_node_t *);
 static bool fat_is_file(fs_node_t *node);
+static dev_handle_t fat_device_get(fs_node_t *node);
 
 /*
@@ -288 +290 @@
 
         *nodepp = nodep;
+        return EOK;
+}
+
+/** Perform basic sanity checks on the file system.
+ *
+ * Verify if values of boot sector fields are sane. Also verify media
+ * descriptor. This is used to rule out cases when a device obviously
+ * does not contain a fat file system.
+ */
+static int fat_sanity_check(fat_bs_t *bs, dev_handle_t dev_handle)
+{
+        fat_cluster_t e0, e1;
+        unsigned fat_no;
+        int rc;
+
+        /* Check number of FATs. */
+        if (bs->fatcnt == 0)
+                return ENOTSUP;
+
+        /* Check total number of sectors. */
+
+        if (bs->totsec16 == 0 && bs->totsec32 == 0)
+                return ENOTSUP;
+
+        if (bs->totsec16 != 0 && bs->totsec32 != 0 &&
+            bs->totsec16 != bs->totsec32) 
+                return ENOTSUP;
+
+        /* Check media descriptor. Must be between 0xf0 and 0xff. */
+        if ((bs->mdesc & 0xf0) != 0xf0)
+                return ENOTSUP;
+
+        /* Check number of sectors per FAT. */
+        if (bs->sec_per_fat == 0)
+                return ENOTSUP;
+
+        /* Check signature of each FAT. */
+
+        for (fat_no = 0; fat_no < bs->fatcnt; fat_no++) {
+                rc = fat_get_cluster(bs, dev_handle, fat_no, 0, &e0);
+                if (rc != EOK)
+                        return EIO;
+
+                rc = fat_get_cluster(bs, dev_handle, fat_no, 1, &e1);
+                if (rc != EOK)
+                        return EIO;
+
+                /* Check that first byte of FAT contains the media descriptor. */
+                if ((e0 & 0xff) != bs->mdesc)
+                        return ENOTSUP;
+
+                /*
+                 * Check that remaining bits of the first two entries are
+                 * set to one.
+                 */
+                if ((e0 >> 8) != 0xff || e1 != 0xffff)
+                        return ENOTSUP;
+        }
+
         return EOK;
 }
@@ -407 +468 @@
 }
 
+int fat_node_open(fs_node_t *fn)
+{
+        /*
+         * Opening a file is stateless, nothing
+         * to be done here.
+         */
+        return EOK;
+}
+
 int fat_node_put(fs_node_t *fn)
 {
@@ -867 +937 @@
 }
 
+dev_handle_t fat_device_get(fs_node_t *node)
+{
+        return 0;
+}
+
 /** libfs operations */
 libfs_ops_t fat_libfs_ops = {
@@ -872 +947 @@
         .match = fat_match,
         .node_get = fat_node_get,
+        .node_open = fat_node_open,
         .node_put = fat_node_put,
         .create = fat_create_node,
@@ -881 +957 @@
         .size_get = fat_size_get,
         .lnkcnt_get = fat_lnkcnt_get,
-        .plb_get_char = fat_plb_get_char,
+        .plb_get_char = fat_plb_get_char,
         .is_directory = fat_is_directory,
-        .is_file = fat_is_file
+        .is_file = fat_is_file,
+        .device_get = fat_device_get
 };
 
@@ -957 +1034 @@
         /* Initialize the block cache */
         rc = block_cache_init(dev_handle, bps, 0 /* XXX */, cmode);
+        if (rc != EOK) {
+                block_fini(dev_handle);
+                ipc_answer_0(rid, rc);
+                return;
+        }
+
+        /* Do some simple sanity checks on the file system. */
+        rc = fat_sanity_check(bs, dev_handle);
         if (rc != EOK) {
                 block_fini(dev_handle);