fatfs.c

该工程是从ecos嵌入式系统下移植过来的一个小型的fat16文件系统

//==========================================================================
//
//      fatfs.c
//
//      FAT file system
//
//==========================================================================
//####ECOSGPLCOPYRIGHTBEGIN####
// -------------------------------------------
// This file is part of eCos, the Embedded Configurable Operating System.
// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
// Copyright (C) 2003 Savin Zlobec
//
// eCos is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 or (at your option) any later version.
//
// eCos is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with eCos; if not, write to the Free Software Foundation, Inc.,
// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
//
// As a special exception, if other files instantiate templates or use macros
// or inline functions from this file, or you compile this file and link it
// with other works to produce a work based on this file, this file does not
// by itself cause the resulting work to be covered by the GNU General Public
// License. However the source code for this file must still be made available
// in accordance with section (3) of the GNU General Public License.
//
// This exception does not invalidate any other reasons why a work based on
// this file might be covered by the GNU General Public License.
//
// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
// at http://sources.redhat.com/ecos/ecos-license/
// -------------------------------------------
//####ECOSGPLCOPYRIGHTEND####
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):           savin (based on ramfs.c)
// Original data:       nickg
// Date:                2003-06-29
// Purpose:             FAT file system
// Description:         This is a FAT filesystem for eCos. 
//
//####DESCRIPTIONEND####
//
//==========================================================================

#include "kernel.h"
#include "fileio.h"

#include "cyg_ass.h"							// assertion macros
#include "types.h"
#include "stat.h"
#include "codes.h"
#include "dirent.h"
#include "string.h"
#include "malloc.h"
#include "io.h"
#include "fatfs.h"
#include "windows.h"
//==========================================================================
// Tracing support defines 

#ifdef FATFS_TRACE_FS_OP
# define TFS 1
#else
# define TFS 0
#endif

#ifdef FATFS_TRACE_FILE_OP
# define TFO 1
#else
# define TFO 0
#endif

//==========================================================================
// Forward definitions

// Filesystem operations
static int fatfs_mount  (cyg_fstab_entry *fste, cyg_mtab_entry *mte);
static int fatfs_umount (cyg_mtab_entry *mte);
static int fatfs_open   (cyg_mtab_entry *mte, cyg_dir dir, const char *name,
                         int mode, cyg_file *fte);
static int fatfs_unlink (cyg_mtab_entry *mte, cyg_dir dir, const char *name);
static int fatfs_mkdir  (cyg_mtab_entry *mte, cyg_dir dir, const char *name);
static int fatfs_rmdir  (cyg_mtab_entry *mte, cyg_dir dir, const char *name);
static int fatfs_rename (cyg_mtab_entry *mte, cyg_dir dir1, const char *name1,
                         cyg_dir dir2, const char *name2 );
static int fatfs_link   (cyg_mtab_entry *mte, cyg_dir dir1, const char *name1,
                         cyg_dir dir2, const char *name2, int type );
static int fatfs_opendir(cyg_mtab_entry *mte, cyg_dir dir, const char *name,
                         cyg_file *fte );
static int fatfs_chdir  (cyg_mtab_entry *mte, cyg_dir dir, const char *name,
                         cyg_dir *dir_out );
static int fatfs_stat   (cyg_mtab_entry *mte, cyg_dir dir, const char *name,
                         struct stat *buf);
static int fatfs_getinfo(cyg_mtab_entry *mte, cyg_dir dir, const char *name,
                         int key, void *buf, int len );
static int fatfs_setinfo(cyg_mtab_entry *mte, cyg_dir dir, const char *name,
                         int key, void *buf, int len );

// File operations
static int fatfs_fo_read   (struct CYG_FILE_TAG *fp, struct CYG_UIO_TAG *uio);
static int fatfs_fo_write  (struct CYG_FILE_TAG *fp, struct CYG_UIO_TAG *uio);
static int fatfs_fo_lseek  (struct CYG_FILE_TAG *fp, off_t *pos, int whence );
static int fatfs_fo_ioctl  (struct CYG_FILE_TAG *fp, CYG_ADDRWORD com,
                            CYG_ADDRWORD data);
static int fatfs_fo_fsync  (struct CYG_FILE_TAG *fp, int mode );        
static int fatfs_fo_close  (struct CYG_FILE_TAG *fp);
static int fatfs_fo_fstat  (struct CYG_FILE_TAG *fp, struct stat *buf );
static int fatfs_fo_getinfo(struct CYG_FILE_TAG *fp, int key, 
                            void *buf, int len );
static int fatfs_fo_setinfo(struct CYG_FILE_TAG *fp, int key, 
                            void *buf, int len );

// Directory operations
static int fatfs_fo_dirread (struct CYG_FILE_TAG *fp, struct CYG_UIO_TAG *uio);
static int fatfs_fo_dirlseek(struct CYG_FILE_TAG *fp, off_t *pos, int whence);

// -------------------------------------------------------------------------
// Directory search data
// Parameters for a directory search. The fields of this structure are
// updated as we follow a pathname through the directory tree.

struct fatfs_dirsearch_t
{
    fatfs_disk_t        *disk;     // Disk info 
    fatfs_node_t        *dir;      // Directory to search
    const char          *path;     // Path to follow
    fatfs_node_t        *node;     // Node found
    const char          *name;     // Last name fragment used
    int                  namelen;  // Name fragment length
    cyg_bool             last;     // Last name in path?
};

typedef struct fatfs_dirsearch_t fatfs_dirsearch_t;

//==========================================================================

#if TFS
static void 
print_disk_info(fatfs_disk_t *disk)
{
    diag_printf("FAT: sector size:        %u\n", disk->sector_size);
    diag_printf("FAT: cluster size:       %u\n", disk->cluster_size);
    diag_printf("FAT: FAT table position: %u\n", disk->fat_tbl_pos);
    diag_printf("FAT: FAT table num ent:  %u\n", disk->fat_tbl_nents);
    diag_printf("FAT: FAT table size:     %u\n", disk->fat_tbl_size);
    diag_printf("FAT: FAT tables num:     %u\n", disk->fat_tbls_num);
    diag_printf("FAT: FAT root dir pos:   %u\n", disk->fat_root_dir_pos);
    diag_printf("FAT: FAT root dir nents: %u\n", disk->fat_root_dir_nents);
    diag_printf("FAT: FAT root dir size:  %u\n", disk->fat_root_dir_size);
    diag_printf("FAT: FAT data position:  %u\n", disk->fat_data_pos);
}
#endif

static void
init_dirsearch(fatfs_dirsearch_t *ds,
               fatfs_disk_t      *disk, 
               fatfs_node_t      *dir,
               const char        *name)
{
    ds->disk    = disk;
    if (NULL == dir)
        ds->dir = disk->root;
    else
        ds->dir = dir;
    ds->path    = name;
    ds->node    = ds->dir;
    ds->namelen = 0;
    ds->last    = false;
}

static int
find_direntry(fatfs_dirsearch_t *ds)
{
    int err;
    cyg_uint32 pos = 0;
    fatfs_node_t node_data;

    printf( "Finding dir entry '%s'", ds->name);

    ds->node = fatfs_node_find(ds->disk, ds->name, 
                               ds->namelen, ds->dir->cluster);

    if (ds->node != NULL)
    {
        printf( "Found dir entry '%s' in cache", ds->name);
        fatfs_node_touch(ds->disk, ds->node);
        return ENOERR;
    }
    
    while (true)
    {   
        err = fatfs_get_dir_entry_node(ds->disk, ds->dir, &pos, &node_data);
        if (err != ENOERR)
            return (err == EEOF ? ENOERR : err);

        if ('\0' == node_data.filename[ds->namelen] &&
            0 == strncasecmp(node_data.filename, ds->name, ds->namelen))
        {
            printf( "Read dir entry '%s' at %d", 
                            node_data.filename, pos);

            ds->node = fatfs_node_alloc(ds->disk, &node_data);
            if (NULL == ds->node)
                return ENOMEM;
            return ENOERR;
        }
        pos++;
    }
}

static int 
find_entry(fatfs_dirsearch_t *ds)
{
    int err;
    const char *name = ds->path;
    const char *n = name;
    char namelen = 0;
    
    // check that we really have a directory
    if( !S_ISDIR(ds->dir->mode) )
    {
        printf( "Entry '%s' not dir", ds->dir->filename);
        return ENOTDIR;
    }
    
    // Isolate the next element of the path name.
    while (*n != '\0' && *n != '/')
        n++, namelen++;

    // If we terminated on a NUL, set last flag.
    if (*n == '\0')
        ds->last = true;

    // update name in dirsearch object
    ds->name    = name;
    ds->namelen = namelen;

    err = find_direntry(ds);
    if (err != ENOERR)
        return err;

    printf( "Entry '%s' %s", name, (ds->node ? "found" : "not found"));
    
    if (ds->node != NULL)
       return ENOERR;
    else
       return ENOENT; 
}

static int
fatfs_find(fatfs_dirsearch_t *ds)
{
    int err;

    printf( "Find path='%s'", ds->path);
    
    // Short circuit empty paths
    if (*(ds->path) == '\0')
        return ENOERR;
    
    // Iterate down directory tree until we find the object
    // we want.
    for(;;)
    {
        err = find_entry(ds);
        
        if (err != ENOERR)
            return err;
        
        if (ds->last)
        {
            printf( "Entry found");
            return ENOERR;
        }

        // Update dirsearch object to search next directory.
        ds->dir = ds->node;
        ds->path += ds->namelen;
        
        // Skip dirname separators
        if (*(ds->path) == '/') ds->path++;
        
        printf( "Find path to go='%s'", ds->path);
    }
}

//==========================================================================
// Filesystem operations

// -------------------------------------------------------------------------
// fatfs_mount()
// Process a mount request. This mainly creates a root for the
// filesystem.

static int 
fatfs_mount(cyg_fstab_entry *fste, cyg_mtab_entry *mte)
{
    cyg_io_handle_t dev_h;
    Cyg_ErrNo err;
    fatfs_disk_t *disk;
    fatfs_node_t root_data;

    printf("Mount fste=%p mte=%p", fste, mte);
    
    printf("Looking up disk device '%s'", mte->devname);
    
    err = cyg_io_lookup(mte->devname, &dev_h);
    if (err != ENOERR)
        return err;

    disk = (fatfs_disk_t *)malloc(sizeof(fatfs_disk_t));
    if (NULL == disk)
        return ENOMEM;
        
    printf( "Initializing FAT table cache"); 
   
    if (ENOERR != fatfs_tcache_create(disk, 10240))
    {
        free(disk);
        return ENOMEM;
    }
    
    printf( "Initializing block cache"); 
 
    disk->dev_h = 0;

    printf( "Initializing disk");
    
    err = fatfs_get_disk_info(disk);
    if (err != ENOERR)
    {
        fatfs_tcache_delete(disk);
        free(disk);
        return err;
    }
   
#if TFS    
    print_disk_info(disk);
#endif

    printf( "Initializing node cache");

    fatfs_node_cache_init(disk);
    
    printf( "Initializing root node");
    
    fatfs_get_root_node(disk, &root_data);
    disk->root = fatfs_node_alloc(disk, &root_data);
    fatfs_node_ref(disk, disk->root);
    
    mte->root = (cyg_dir)disk->root;
    mte->data = (CYG_ADDRWORD)disk;

    printf( "Disk mounted");

    return ENOERR;
}

// -------------------------------------------------------------------------
// fatfs_umount()
// Unmount the filesystem. This will currently only succeed if the
// filesystem is empty.

static int
fatfs_umount(cyg_mtab_entry *mte)
{
    fatfs_disk_t *disk = (fatfs_disk_t *)mte->data;
    fatfs_node_t *root = (fatfs_node_t *)mte->root;

    printf( "Umount mte=%p %d live nodes %d dead nodes", 
                    mte, fatfs_get_live_node_count(disk), 
                    fatfs_get_dead_node_count(disk));

    if (root->refcnt > 1)
        return EBUSY;
    
    if (fatfs_get_live_node_count(disk) != 1)
        return EBUSY;

    fatfs_node_unref(disk, root);
    fatfs_node_cache_flush(disk);
    fatfs_tcache_delete(disk);
    // FIXME: cache delete can fail if cache can't be synced
    free(disk);
    
    mte->root = CYG_DIR_NULL;
    mte->data = (CYG_ADDRWORD)NULL;
    
    printf( "Disk umounted");
    
    return ENOERR;
}