WebSVN – HelenOS – Diff – /branches/tracing/uspace/srv/fs/fat/fat.h

 /*
- * Copyright (c) 2007 Jakub Jermar
+ * 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:
 #include <ipc/ipc.h>
 #include <libfs.h>
 #include <atomic.h>
 #include <sys/types.h>
 #include <bool.h>
+#include "../../vfs/vfs.h"
 #define dprintf(...)    printf(__VA_ARGS__)
 typedef struct {
     uint8_t     ji[3];      /**< Jump instruction. */
     uint8_t     oem_name[8];
     /* BIOS Parameter Block */
     uint16_t    bps;        /**< Bytes per sector. */
     uint8_t     spc;        /**< Sectors per cluster. */
-    uint16_t    rsc;        /**< Reserved sector count. */
+    uint16_t    rscnt;      /**< Reserved sector count. */
     uint8_t     fatcnt;     /**< Number of FATs. */
     uint16_t    root_ent_max;   /**< Maximum number of root directory
                          entries. */
-    uint16_t    totsec;     /**< Total sectors. */
+    uint16_t    totsec16;   /**< Total sectors. 16-bit version. */
     uint8_t     mdesc;      /**< Media descriptor. */
     uint16_t    sec_per_fat;    /**< Sectors per FAT12/FAT16. */
     uint16_t    sec_per_track;  /**< Sectors per track. */
     uint16_t    headcnt;    /**< Number of heads. */
     uint32_t    hidden_sec; /**< Hidden sectors. */
-    uint32_t    total_sec;  /**< Total sectors. */
+    uint32_t    totsec32;   /**< Total sectors. 32-bit version. */
     union {
         struct {
             /* FAT12/FAT16 only: Extended BIOS Parameter Block */
             /** Physical drive number. */
             /** Extended boot signature. */
             uint8_t     ebs;
             /** Serial number. */
             uint32_t    id;
             /** Volume label. */
-            uint8_t     label;
+            uint8_t     label[11];
             /** FAT type. */
             uint8_t     type[8];
             /** Boot code. */
             uint8_t     boot_code[420];
             /** Signature. */
             uint16_t    signature;
         } __attribute__ ((packed));
     };
 } __attribute__ ((packed)) fat_bs_t;
+#define FAT_ATTR_RDONLY     (1 << 0)
+#define FAT_ATTR_VOLLABEL   (1 << 3)
+#define FAT_ATTR_SUBDIR     (1 << 4)
 typedef struct {
     uint8_t     name[8];
     uint8_t     ext[3];
     uint8_t     attr;
     uint8_t     reserved;
         uint16_t    firstc_lo;  /* FAT32 */
     };
     uint32_t    size;
 } __attribute__ ((packed)) fat_dentry_t;
+typedef uint16_t fat_cluster_t;
+typedef enum {
+    FAT_INVALID,
+    FAT_DIRECTORY,
+    FAT_FILE
+} fat_node_type_t;
+struct fat_node;
+/** FAT index structure.
+ *
+ * This structure exists to help us to overcome certain limitations of the FAT
+ * file system design.  The problem with FAT is that it is hard to find
+ * an entity which could represent a VFS index.  There are two candidates:
+ *
+ * a) number of the node's first cluster
+ * b) the pair of the parent directory's first cluster and the dentry index
+ *    within the parent directory
+ *
+ * We need VFS indices to be:
+ * A) unique
+ * B) stable in time, at least until the next mount
+ *
+ * Unfortunately a) does not meet the A) criterion because zero-length files
+ * will have the first cluster field cleared.  And b) does not meet the B)
+ * criterion because unlink() and rename() will both free up the original
+ * dentry, which contains all the essential info about the file.
+ *
+ * Therefore, a completely opaque indices are used and the FAT server maintains
+ * a mapping between them and otherwise nice b) variant.  On rename(), the VFS
+ * index stays unaltered, while the internal FAT "physical tree address"
+ * changes.  The unlink case is also handled this way thanks to an in-core node
+ * pointer embedded in the index structure.
+ */
+typedef struct {
+    /** Used indices (position) hash table link. */
+    link_t      uph_link;
+    /** Used indices (index) hash table link. */
+    link_t      uih_link;
+    dev_handle_t    dev_handle;
+    fs_index_t  index;
+    /**
+     * Parent node's first cluster.
+     * Zero is used if this node is not linked, in which case nodep must
+     * contain a pointer to the in-core node structure.
+     * One is used when the parent is the root directory.
+     */
+    fat_cluster_t   pfc;
+    /** Directory entry index within the parent node. */
+    unsigned    pdi;
+    /** Pointer to in-core node instance. */
+    struct fat_node *nodep;
+} fat_idx_t;
+/** FAT in-core node. */
+typedef struct fat_node {
+    fat_node_type_t     type;
+    fat_idx_t       *idx;
+    /**
+     *  Node's first cluster.
+     *  Zero is used for zero-length nodes.
+     *  One is used to mark root directory.
+     */
+    fat_cluster_t       firstc;
+    /** FAT in-core node free list link. */
+    link_t          ffn_link;
+    size_t          size;
+    unsigned        lnkcnt;
+    unsigned        refcnt;
+    bool            dirty;
+} fat_node_t;
 extern fs_reg_t fat_reg;
 extern void fat_lookup(ipc_callid_t, ipc_call_t *);
+extern fat_idx_t *fat_idx_get_by_pos(dev_handle_t, fat_cluster_t, unsigned);
+extern fat_idx_t *fat_idx_get_by_index(dev_handle_t, fs_index_t);
 #endif
 /**
  * @}
  */

Subversion Repositories HelenOS

(root)/branches/tracing/uspace/srv/fs/fat/fat.h – Rev 2787 → 2925