Subversion Repositories openrisc

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

//

//      ramfs.c

//

//      RAM file system

//

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

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

//

// 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):           nickg

// Contributors:        nickg

// Date:                2000-07-25

// Purpose:             RAM file system

// Description:         This is a RAM filesystem for eCos. It attempts to

//                      provide full POSIX-compatible filesystem behaviour

//                      while at the same time being efficient in terms of

//                      time and space used.

//                      

//

//####DESCRIPTIONEND####

//

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

// 

// General Description

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

// 

// This is an implementation of a RAM filesystem for eCos. Its goal is

// to provide a working example of a filesystem that provides most of

// the required POSIX functionality. And obviously it may also be

// useful in its own right.

//

//

// Nodes

// -----

//

// All files and directories are represented by node objects. Each

// ramfs_node structure contains the following fields:

//

// mode   - Node type, file or directory.

// refcnt - Number of references to this node. For files each open counts as

//          a reference and for directories a node is referenced when it is made

//          current directory, or is opened for reading.

// nlink  - Number of links to this node. Each directory entry that references

//          this node is a link. 

// size   - Size of the data in this node in bytes.

// atime  - Last time this node was accessed.

// mtime  - Last time the data in this node was modified.

// ctime  - Last time the status information in this node was changed.

//

// The data storage in a node is controlled by the configuration and

// can take two forms. These will be described later.

//          

// Directories

// -----------

//

// A directory is a node whose data is a list of directory entries. To

// simplify management of these, long directory entries are split into

// a chain of fixed size ramfs_dirent structures. These contain the

// following fields:

//

// node    - Pointer to node referenced by this entry. This is present in

//           every directory entry fragment

// inuse   - Set to 1 if this entry is in use, zero if it is free.

// first   - Set to 1 if this is the first fragment of a directory entry.

// last    - Set to 1 if this is the last fragment of a directory entry.

// namelen - The size of the whole file name.

// fraglen - The number of bytes of the file name that are stored in this

//           fragment.

// next    - The offset of the next fragment of this directory entry.

// name    - The characters of the fragment of the file name stored in this

//           entry.

//

// Small file names are stored in a single fragment. Longer names are

// stored in a chain of fragments.

//

// Data Storage

// ------------

//

// Two data storage mechanisms may be configured, the SIMPLE and the

// BLOCKS mechanisms.

//

// SIMPLE Data Storage

// ~~~~~~~~~~~~~~~~~~~

//

// This mechanism simply uses malloc() and free() to allocate the

// memory for both nodes and file data. File data is stored in a

// single malloced vector that is realloced as necessary to acquire

// more space. 

//

// The advantage of this approach is that the RAM filesystem only uses

// as much memory as it needs, the rest is available for use by other

// components. It also requires much simpler data structures and code

// in the filesystem to manage. However, if any files get to be a

// significant proportion of the size of the heap, there is the danger

// that fragmentation will prevent any further extension of some

// files, even if there is enough memory in total. It also requires an

// implementation of malloc() to be present. If this needs to be

// present for other components,then this is not a significant

// overhead, but including it just for use by this filesystem

// represents a major addition of code and data structures.

//

//

// BLOCKS Data Storage

// ~~~~~~~~~~~~~~~~~~~

//

// This mechanism divides the memory used for file storage into fixed

// sized blocks. These blocks may either be allocated using

// malloc()/free(), or may be obtained from a array of blocks reserved

// for the purpose. Configuration allows the block size to be

// selected, as well as the allocation mechanism, and in the case of a

// block array, whether it is defined here or by an external

// component.

// 

// Data storage in nodes is arranges in three arrays of pointers to

// blocks. The first array points directly to data blocks, the second

// to blocks which themselves contain pointers to data blocks, and the

// third to blocks which contain pointers to blocks which contain

// pointers to data blocks. In the default configuration These last

// two arrays have only one element each.

// 

// The following shows how the data is arranged in a fully populated

// file with a 256 byte block size using the default configuration.

// 

//      Node

// ~            ~

// |            |

// |            |

// +------------+

// |     *------+--------> data block 0

// +------------+

// |     *------+--------> data block 1

// +------------+

// |     *------+--------> data block 2

// +------------+

// |     *------+--------> data block 3

// +------------+

// |     *------+--------> data block 4

// +------------+

// |     *------+--------> data block 5

// +------------+

// |     *------+--------> data block 6

// +------------+

// |     *------+--------> data block 7

// +------------+

// |     *------+--------> +------------+

// +------------+          |     *------+--------> data block 8

// |     *------+----+     +------------+

// +------------+    |     |            |

//                   |     ~            ~

//                   |     |            |

//                   |     +------------+

//                   |     |     *------+--------> data block 71

//                   |     +------------+

//                   |     

//                   +---->+------------+         +------------+

//                         |     *------+-------->|     *------+---->data block 72

//                         +------------+         +------------+

//                         |            |         |            |

//                         ~            ~         ~            ~

//                         |            |         |            |

//                         +------------+         +------------+

//                         |     *------+---+     |     *------+----> data block 135

//                         +------------+   |     +------------+

//                                          |

//                                          |     +------------+

//                                          +---->|     *------+----> data block 4104

//                                                +------------+

//                                                |            |

//                                                ~            ~

//                                                |            |

//                                                +------------+

//                                                |     *------+----> data block 4167

//                                                +------------+

// 

// 

//

// The advantages of this approach are that, first, memory usage is

// divided into discreet fixed size blocks which are easier to

// manage. When using malloc() to allocate them, they will fit into

// any free memory of at least the right size. Using the block array

// option removes the need to have a malloc() implementation at all.

//

// The disadvantages of this mechanism are that, first, when using

// malloc() to allocate blocks, the per-block memory allocator

// overhead is paid for each block, rather than per file. This may

// result in less memory overall being available for data

// storage. When using the block array, it is permanently reserved for

// use by the ram filesystem, and is not available for use by other

// components.

//

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

#include <pkgconf/system.h>

#include <pkgconf/hal.h>

#include <pkgconf/kernel.h>

#include <pkgconf/io_fileio.h>

#include <pkgconf/fs_ram.h>

#include <cyg/kernel/ktypes.h>         // base kernel types

#include <cyg/infra/cyg_trac.h>        // tracing macros

#include <cyg/infra/cyg_ass.h>         // assertion macros

#include <unistd.h>

#include <sys/types.h>

#include <fcntl.h>

#include <sys/stat.h>

#include <errno.h>

#include <dirent.h>

#include <stdlib.h>

#include <string.h>

#include <cyg/fileio/fileio.h>

#include <cyg/kernel/kapi.h>

#include <cyg/infra/diag.h>

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

// Sizes derived from configuration

// -------------------------------------------------------------------------

// Simple malloc based allocator parameters

#ifdef CYGPKG_FS_RAM_SIMPLE

#define RAMFS_FILESIZE_MAX      UINT_MAX

#else

// -------------------------------------------------------------------------

// Block allocator parameters

// The number of nodes per block

#define RAMFS_NODES_PER_BLOCK (CYGNUM_RAMFS_BLOCK_SIZE/sizeof(ramfs_node))

// The number of indirect pointers that can be stored in a single data block

#define RAMFS_INDIRECT_PER_BLOCK (CYGNUM_RAMFS_BLOCK_SIZE/sizeof(ramfs_block *))

// The number of directory entries that can be stored in a single data block

#define RAMFS_DIRENT_PER_BLOCK  (CYGNUM_RAMFS_BLOCK_SIZE/sizeof(ramfs_dirent))

// Number of bytes contained in a one level indirect block

#define RAMFS_INDIRECT1_BLOCK_EXTENT (RAMFS_INDIRECT_PER_BLOCK* \

                                      CYGNUM_RAMFS_BLOCK_SIZE)

// number of bytes contained in a two level indirect block

#define RAMFS_INDIRECT2_BLOCK_EXTENT (RAMFS_INDIRECT_PER_BLOCK* \

                                      RAMFS_INDIRECT_PER_BLOCK* \

                                      CYGNUM_RAMFS_BLOCK_SIZE)

// The maximum data offset for data directly accessed from the node

#define RAMFS_DIRECT_MAX        (CYGNUM_RAMFS_BLOCKS_DIRECT*CYGNUM_RAMFS_BLOCK_SIZE)

// The maximum data offset for data accessed from the single level indirect blocks

#define RAMFS_INDIRECT1_MAX     (RAMFS_DIRECT_MAX+                      \

                                 (CYGNUM_RAMFS_BLOCKS_INDIRECT1*        \

                                  RAMFS_INDIRECT1_BLOCK_EXTENT))

// The maximum data offset for data accessed from the two level indirect blocks

#define RAMFS_INDIRECT2_MAX     (RAMFS_INDIRECT1_MAX+                   \

                                 (CYGNUM_RAMFS_BLOCKS_INDIRECT2*        \

                                  RAMFS_INDIRECT2_BLOCK_EXTENT))

// The maximum size of a file

#define RAMFS_FILESIZE_MAX      RAMFS_INDIRECT2_MAX

#endif

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

// Forward definitions

// Filesystem operations

static int ramfs_mount    ( cyg_fstab_entry *fste, cyg_mtab_entry *mte );

static int ramfs_umount   ( cyg_mtab_entry *mte );

static int ramfs_open     ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,

                             int mode,  cyg_file *fte );

static int ramfs_unlink   ( cyg_mtab_entry *mte, cyg_dir dir, const char *name );

static int ramfs_mkdir    ( cyg_mtab_entry *mte, cyg_dir dir, const char *name );

static int ramfs_rmdir    ( cyg_mtab_entry *mte, cyg_dir dir, const char *name );

static int ramfs_rename   ( cyg_mtab_entry *mte, cyg_dir dir1, const char *name1,

                             cyg_dir dir2, const char *name2 );

static int ramfs_link     ( cyg_mtab_entry *mte, cyg_dir dir1, const char *name1,

                             cyg_dir dir2, const char *name2, int type );

static int ramfs_opendir  ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,

                             cyg_file *fte );

static int ramfs_chdir    ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,

                             cyg_dir *dir_out );

static int ramfs_stat     ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,

                             struct stat *buf);

static int ramfs_getinfo  ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,

                             int key, void *buf, int len );

static int ramfs_setinfo  ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,

                             int key, void *buf, int len );

// File operations

static int ramfs_fo_read      (struct CYG_FILE_TAG *fp, struct CYG_UIO_TAG *uio);

static int ramfs_fo_write     (struct CYG_FILE_TAG *fp, struct CYG_UIO_TAG *uio);

static int ramfs_fo_lseek     (struct CYG_FILE_TAG *fp, off_t *pos, int whence );

static int ramfs_fo_ioctl     (struct CYG_FILE_TAG *fp, CYG_ADDRWORD com,

                                CYG_ADDRWORD data);

static int ramfs_fo_fsync     (struct CYG_FILE_TAG *fp, int mode );

static int ramfs_fo_close     (struct CYG_FILE_TAG *fp);

static int ramfs_fo_fstat     (struct CYG_FILE_TAG *fp, struct stat *buf );

static int ramfs_fo_getinfo   (struct CYG_FILE_TAG *fp, int key, void *buf, int len );

static int ramfs_fo_setinfo   (struct CYG_FILE_TAG *fp, int key, void *buf, int len );

// Directory operations

static int ramfs_fo_dirread      (struct CYG_FILE_TAG *fp, struct CYG_UIO_TAG *uio);

static int ramfs_fo_dirlseek     (struct CYG_FILE_TAG *fp, off_t *pos, int whence );

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

// Filesystem table entries

// -------------------------------------------------------------------------

// Fstab entry.

// This defines the entry in the filesystem table.

// For simplicity we use _FILESYSTEM synchronization for all accesses since

// we should never block in any filesystem operations.

FSTAB_ENTRY( ramfs_fste, "ramfs", 0,

             CYG_SYNCMODE_FILE_FILESYSTEM|CYG_SYNCMODE_IO_FILESYSTEM,

             ramfs_mount,

             ramfs_umount,

             ramfs_open,

             ramfs_unlink,

             ramfs_mkdir,

             ramfs_rmdir,

             ramfs_rename,

             ramfs_link,

             ramfs_opendir,

             ramfs_chdir,

             ramfs_stat,

             ramfs_getinfo,

             ramfs_setinfo);

// -------------------------------------------------------------------------

// File operations.

// This set of file operations are used for normal open files.

static cyg_fileops ramfs_fileops =

{

    ramfs_fo_read,

    ramfs_fo_write,

    ramfs_fo_lseek,

    ramfs_fo_ioctl,

    cyg_fileio_seltrue,

    ramfs_fo_fsync,

    ramfs_fo_close,

    ramfs_fo_fstat,

    ramfs_fo_getinfo,

    ramfs_fo_setinfo

};

// -------------------------------------------------------------------------

// Directory file operations.

// This set of operations are used for open directories. Most entries

// point to error-returning stub functions. Only the read, lseek and

// close entries are functional.

static cyg_fileops ramfs_dirops =

{

    ramfs_fo_dirread,

    (cyg_fileop_write *)cyg_fileio_enosys,

    ramfs_fo_dirlseek,

    (cyg_fileop_ioctl *)cyg_fileio_enosys,

    cyg_fileio_seltrue,

    (cyg_fileop_fsync *)cyg_fileio_enosys,

    ramfs_fo_close,

    (cyg_fileop_fstat *)cyg_fileio_enosys,

    (cyg_fileop_getinfo *)cyg_fileio_enosys,

    (cyg_fileop_setinfo *)cyg_fileio_enosys

};

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

// Data typedefs

// Some forward typedefs for the main data structures.

struct ramfs_node;

typedef struct ramfs_node ramfs_node;

struct ramfs_dirent;

typedef struct ramfs_dirent ramfs_dirent;

#ifndef CYGPKG_FS_RAM_SIMPLE

typedef cyg_uint8 ramfs_block[CYGNUM_RAMFS_BLOCK_SIZE];

#endif

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

// File and directory node

// This data structure represents a file or directory.

struct ramfs_node

{

    mode_t              mode;           // node type

    cyg_ucount32        refcnt;         // open file/current dir references

    nlink_t             nlink;          // number of links to this node

    size_t              size;           // size of file in bytes

    time_t              atime;          // last access time

    time_t              mtime;          // last modified time

    time_t              ctime;          // last changed status time

#ifdef CYGPKG_FS_RAM_SIMPLE

    // The data storage in this case consists of a single

    // malloced memory block, together with its size.

    size_t              datasize;       // size of data block

    cyg_uint8           *data;          // malloced data buffer

#else

    // The data storage in this case consists of arrays of pointers

    // to data blocks. 

#if CYGNUM_RAMFS_BLOCKS_DIRECT > 0

    // Directly accessible blocks from the inode.

    ramfs_block         *direct[CYGNUM_RAMFS_BLOCKS_DIRECT];

#endif

#if  CYGNUM_RAMFS_BLOCKS_INDIRECT1 > 0

    // Single level indirection

    ramfs_block         **indirect1[CYGNUM_RAMFS_BLOCKS_INDIRECT1];

#endif

#if  CYGNUM_RAMFS_BLOCKS_INDIRECT2 > 0

    // Two level indirection

    ramfs_block         ***indirect2[CYGNUM_RAMFS_BLOCKS_INDIRECT2];

#endif

#endif

};

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

// Directory entry.

// Fixed sized entry containing a fragment of the name of a file/directory.

struct ramfs_dirent

{

    ramfs_node          *node;          // pointer to node

    unsigned int        inuse:1,        // entry in use?

                        first:1,        // first directory entry fragment?

                        last:1,         // last directory entry fragment?

                        namelen:8,      // bytes in whole name

                        fraglen:8;      // bytes in name fragment

    off_t               next;           // offset of next dirent

    // Name fragment, fills rest of entry.

    char                name[CYGNUM_RAMFS_DIRENT_SIZE-

                             sizeof(ramfs_node *)-

                             sizeof( cyg_uint32)-

                             sizeof(off_t)];

};

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

// 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 ramfs_dirsearch

{

    ramfs_node          *dir;           // directory to search

    const char          *path;          // path to follow

    ramfs_node          *node;          // Node found

    const char          *name;          // last name fragment used

    int                 namelen;        // name fragment length

    cyg_bool            last;           // last name in path?

};

typedef struct ramfs_dirsearch ramfs_dirsearch;

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

// Forward defs

static int del_direntry( ramfs_node *dir, const char *name, int namelen );

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

// Block array

// This is used for block allocation when malloc is not being used.

#ifdef CYGPKG_FS_RAM_BLOCKS_ARRAY

# ifdef CYGPKG_FS_RAM_BLOCKS_ARRAY_EXTERN

// Array is defined externally with a user-supplied name

__externC ramfs_block CYGPKG_FS_RAM_BLOCKS_ARRAY_NAME[CYGNUM_FS_RAM_BLOCKS_ARRAY_SIZE];

// Translate into a usable common name

#define ramfs_block_array CYGPKG_FS_RAM_BLOCKS_ARRAY_NAME

# else

// Array is defined here

static ramfs_block cyg_ramfs_block_array[CYGNUM_FS_RAM_BLOCKS_ARRAY_SIZE];

#define ramfs_block_array cyg_ramfs_block_array

# endif

// Pointer to list of free blocks

static ramfs_block *block_free_list = NULL;

#endif

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

// Block allocation

#ifndef CYGPKG_FS_RAM_SIMPLE

// -------------------------------------------------------------------------

// block_init()

// Initialize the block allocator by chaining them all together on

// block_free_list.

#ifdef CYGPKG_FS_RAM_BLOCKS_ARRAY

static void block_init()

{

    static cyg_bool initialized = false;

    int i;

    if( !initialized )

    {

        for( i = 0; i < CYGNUM_FS_RAM_BLOCKS_ARRAY_SIZE; i++ )

        {

            ramfs_block *b = &ramfs_block_array[i];

            *(ramfs_block **)b = block_free_list;

            block_free_list = b;

        }

        initialized = true;

    }

}

#endif

// -------------------------------------------------------------------------

// block_alloc()

// Allocate a block for data storage.

// If we have a block array, just pick the first off the free list.

// If we are mallocing, call malloc() to get it.

static ramfs_block *block_alloc(void)

{

    ramfs_block *b;

#ifdef CYGPKG_FS_RAM_BLOCKS_ARRAY

    block_init();       // Check blocks are initialized

    // pick first block off free list.

    b = block_free_list;

    // and advance list

    if( b != NULL )

        block_free_list = *(ramfs_block **)b;

#else

    b = malloc(CYGNUM_RAMFS_BLOCK_SIZE);

#endif

    // Clear the block to zero if it was allocated

    if( b != NULL )

        memset( b, 0, CYGNUM_RAMFS_BLOCK_SIZE );

    return b;

}

// -------------------------------------------------------------------------

// block_free()

// Free a block. Depending on the configuration send it back to the

// heap or put it back on free list.

static void block_free( ramfs_block *b )

{

#ifdef CYGPKG_FS_RAM_BLOCKS_ARRAY

    // Put the block back on the free list

    *(ramfs_block **)b = block_free_list;

    block_free_list = b;

#else    

    // Call free() to return it to the memory pool

    free( b );

#endif

}

#endif

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

// Node buffer management

// There are two versions of this, one for the _SIMPLE variant and one for

// the _BLOCKS variant. In both cases the interface to this code is via the

// findbuffer_node() and freebuffer_node() functions.

#ifdef CYGPKG_FS_RAM_SIMPLE

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

// SIMPLE buffer management.

// Each node has a data buffer pointer and a size. This buffer is

// realloc()ed as needed.

// -------------------------------------------------------------------------

// findbuffer_node()

// return a pointer to the data at the indicated file position, extending

// the buffer if required.

static int findbuffer_node( ramfs_node  *node,  // node pointer

                            off_t pos,          // data position to get

                            cyg_uint8 **buffer, // returned buffer pointer

                            size_t *size,       // returned buffer size

                            cyg_bool alloc)     // extend allocation?

{

    if( alloc && (pos == node->datasize || node->datasize == 0) )

    {

        // If we are allowed to alloc new data, and we are at the end of the

        // current data allocation, or there is no data present, allocate or

        // extend the data buffer.

        cyg_uint8 *newdata;

        if( node->data == NULL )

            newdata = malloc( CYGNUM_RAMFS_REALLOC_INCREMENT );

        else

            newdata = realloc( node->data, pos+CYGNUM_RAMFS_REALLOC_INCREMENT );

        if( newdata == NULL ) return ENOSPC;

        else memset( newdata+pos, 0, CYGNUM_RAMFS_REALLOC_INCREMENT );

        node->data = newdata;

        node->datasize = pos+CYGNUM_RAMFS_REALLOC_INCREMENT;

    }

    else if( pos > node->datasize )

    {

        // Indicate end of data.

        *size = 0;

        return ENOERR;

    }

    *buffer = node->data+pos;

    *size = node->datasize-pos;

    return ENOERR;

}

// -------------------------------------------------------------------------

// freebuffer_node()

// Empty out the data storage from the node.

static int freebuffer_node( ramfs_node *node )

{

    if( node->data != NULL )

    {

        free( node->data );

    }

    node->data = NULL;

    node->datasize = 0;

    return ENOERR;

}

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

#else

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

// _BLOCKS storage management.

// Data storage in the node is by means of a set of arrays of pointers to

// blocks. The first array points directly to the data blocks. Subsequent

// arrays point to single and double indirect blocks respectively. 

// -------------------------------------------------------------------------

// findbuffer_direct()

// Indexes into an array of block pointers and extracts a pointer to the

// data at offset _pos_, allocating new blocks if required.

static int findbuffer_direct( off_t pos,

                              ramfs_block **blocks,

                              int nblocks,

                              cyg_uint8 **buffer,

                              size_t *size,

                              cyg_bool alloc)

{

    int bi = pos / CYGNUM_RAMFS_BLOCK_SIZE;

    int bpos = pos % CYGNUM_RAMFS_BLOCK_SIZE;

    ramfs_block *b;

    *buffer = NULL;

    *size = 0;

    if( bi >= nblocks )

        return ENOERR;

    b = blocks[bi];

    if( b == NULL )

    {

        // There is no block there. If _alloc_ is true we can fill the

        // slot in with a new block. If it is false, we indicate end of

        // data with a zero size result.

        if( alloc )

        {

            b = block_alloc();

            if( b == NULL )

                return ENOSPC;

            blocks[bi] = b;

        }

        else return ENOERR;

    }

    *buffer = &((*b)[bpos]);

    *size = CYGNUM_RAMFS_BLOCK_SIZE - bpos;

    return ENOERR;

}