fat_write.c

//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//                            FAT16/32 File IO Library
//                                    V2.6
//                              Ultra-Embedded.com
//                            Copyright 2003 - 2012
//
//                         Email: admin@ultra-embedded.com
//
//                                License: GPL
//   If you would like a version with a more permissive license for use in
//   closed source commercial applications please contact me for details.
//-----------------------------------------------------------------------------
//
// This file is part of FAT File IO Library.
//
// FAT File IO Library 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 of the License, or
// (at your option) any later version.
//
// FAT File IO Library 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 FAT File IO Library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
#include <string.h>
#include "fat_defs.h"
#include "fat_access.h"
#include "fat_table.h"
#include "fat_write.h"
#include "fat_string.h"
#include "fat_misc.h"

#if FATFS_INC_WRITE_SUPPORT
//-----------------------------------------------------------------------------
// fatfs_add_free_space: Allocate another cluster of free space to the end
// of a files cluster chain.
//-----------------------------------------------------------------------------
int fatfs_add_free_space(struct fatfs *fs, uint32 *startCluster, uint32 clusters)
{
    uint32 i;
    uint32 nextcluster;
    uint32 start = *startCluster;

    // Set the next free cluster hint to unknown
    if (fs->next_free_cluster != FAT32_LAST_CLUSTER)
        fatfs_set_fs_info_next_free_cluster(fs, FAT32_LAST_CLUSTER);

    for (i=0;i<clusters;i++)
    {
        // Start looking for free clusters from the beginning
        if (fatfs_find_blank_cluster(fs, fs->rootdir_first_cluster, &nextcluster))
        {
            // Point last to this
            fatfs_fat_set_cluster(fs, start, nextcluster);

            // Point this to end of file
            fatfs_fat_set_cluster(fs, nextcluster, FAT32_LAST_CLUSTER);

            // Adjust argument reference
            start = nextcluster;
            if (i == 0)
                *startCluster = nextcluster;
        }
        else
            return 0;
    }

    return 1;
}
//-----------------------------------------------------------------------------
// fatfs_allocate_free_space: Add an ammount of free space to a file either from
// 'startCluster' if newFile = false, or allocating a new start to the chain if
// newFile = true.
//-----------------------------------------------------------------------------
int fatfs_allocate_free_space(struct fatfs *fs, int newFile, uint32 *startCluster, uint32 size)
{
    uint32 clusterSize;
    uint32 clusterCount;
    uint32 nextcluster;

    if (size==0)
        return 0;

    // Set the next free cluster hint to unknown
    if (fs->next_free_cluster != FAT32_LAST_CLUSTER)
        fatfs_set_fs_info_next_free_cluster(fs, FAT32_LAST_CLUSTER);

    // Work out size and clusters
    clusterSize = fs->sectors_per_cluster * FAT_SECTOR_SIZE;
    clusterCount = (size / clusterSize);

    // If any left over
    if (size-(clusterSize*clusterCount))
        clusterCount++;

    // Allocated first link in the chain if a new file
    if (newFile)
    {
        if (!fatfs_find_blank_cluster(fs, fs->rootdir_first_cluster, &nextcluster))
            return 0;

        // If this is all that is needed then all done
        if (clusterCount==1)
        {
            fatfs_fat_set_cluster(fs, nextcluster, FAT32_LAST_CLUSTER);
            *startCluster = nextcluster;
            return 1;
        }
    }
    // Allocate from end of current chain (startCluster is end of chain)
    else
        nextcluster = *startCluster;

    if (!fatfs_add_free_space(fs, &nextcluster, clusterCount))
            return 0;

    return 1;
}
//-----------------------------------------------------------------------------
// fatfs_find_free_dir_offset: Find a free space in the directory for a new entry
// which takes up 'entryCount' blocks (or allocate some more)
//-----------------------------------------------------------------------------
static int fatfs_find_free_dir_offset(struct fatfs *fs, uint32 dirCluster, int entryCount, uint32 *pSector, uint8 *pOffset)
{
    struct fat_dir_entry *directoryEntry;
    uint8 item=0;
    uint16 recordoffset = 0;
    uint8 i=0;
    int x=0;
    int possible_spaces = 0;
    int start_recorded = 0;

    // No entries required?
    if (entryCount == 0)
        return 0;

    // Main cluster following loop
    while (1)
    {
        // Read sector
        if (fatfs_sector_reader(fs, dirCluster, x++, 0))
        {
            // Analyse Sector
            for (item = 0; item < FAT_DIR_ENTRIES_PER_SECTOR; item++)
            {
                // Create the multiplier for sector access
                recordoffset = FAT_DIR_ENTRY_SIZE * item;

                // Overlay directory entry over buffer
                directoryEntry = (struct fat_dir_entry*)(fs->currentsector.sector+recordoffset);

                // LFN Entry
                if (fatfs_entry_lfn_text(directoryEntry))
                {
                    // First entry?
                    if (possible_spaces == 0)
                    {
                        // Store start
                        *pSector = x-1;
                        *pOffset = item;
                        start_recorded = 1;
                    }

                    // Increment the count in-case the file turns
                    // out to be deleted...
                    possible_spaces++;
                }
                // SFN Entry
                else
                {
                    // Has file been deleted?
                    if (fs->currentsector.sector[recordoffset] == FILE_HEADER_DELETED)
                    {
                        // First entry?
                        if (possible_spaces == 0)
                        {
                            // Store start
                            *pSector = x-1;
                            *pOffset = item;
                            start_recorded = 1;
                        }

                        possible_spaces++;

                        // We have found enough space?
                        if (possible_spaces >= entryCount)
                            return 1;

                        // Else continue counting until we find a valid entry!
                    }
                    // Is the file entry empty?
                    else if (fs->currentsector.sector[recordoffset] == FILE_HEADER_BLANK)
                    {
                        // First entry?
                        if (possible_spaces == 0)
                        {
                            // Store start
                            *pSector = x-1;
                            *pOffset = item;
                            start_recorded = 1;
                        }

                        // Increment the blank entries count
                        possible_spaces++;

                        // We have found enough space?
                        if (possible_spaces >= entryCount)
                            return 1;
                    }
                    // File entry is valid
                    else
                    {
                        // Reset all flags
                        possible_spaces = 0;
                        start_recorded = 0;
                    }
                }
            } // End of for
        } // End of if
        // Run out of free space in the directory, allocate some more
        else
        {
            uint32 newCluster;

            // Get a new cluster for directory
            if (!fatfs_find_blank_cluster(fs, fs->rootdir_first_cluster, &newCluster))
                return 0;

            // Add cluster to end of directory tree
            if (!fatfs_fat_add_cluster_to_chain(fs, dirCluster, newCluster))
                return 0;

            // Erase new directory cluster
            memset(fs->currentsector.sector, 0x00, FAT_SECTOR_SIZE);
            for (i=0;i<fs->sectors_per_cluster;i++)
            {
                if (!fatfs_write_sector(fs, newCluster, i, 0))
                    return 0;
            }

            // If non of the name fitted on previous sectors
            if (!start_recorded)
            {
                // Store start
                *pSector = (x-1);
                *pOffset = 0;
                start_recorded = 1;
            }

            return 1;
        }
    } // End of while loop

    return 0;
}
//-----------------------------------------------------------------------------
// fatfs_add_file_entry: Add a directory entry to a location found by FindFreeOffset
//-----------------------------------------------------------------------------
int fatfs_add_file_entry(struct fatfs *fs, uint32 dirCluster, char *filename, char *shortfilename, uint32 startCluster, uint32 size, int dir)
{
    uint8 item=0;
    uint16 recordoffset = 0;
    uint8 i=0;
    uint32 x=0;
    int entryCount;
    struct fat_dir_entry shortEntry;
    int dirtySector = 0;

    uint32 dirSector = 0;
    uint8 dirOffset = 0;
    int foundEnd = 0;

    uint8 checksum;
    uint8 *pSname;

    // No write access?
    if (!fs->disk_io.write_media)
        return 0;

#if FATFS_INC_LFN_SUPPORT
    // How many LFN entries are required?
    // NOTE: We always request one LFN even if it would fit in a SFN!
    entryCount = fatfs_lfn_entries_required(filename);
    if (!entryCount)
        return 0;
#else
    entryCount = 0;
#endif

    // Find space in the directory for this filename (or allocate some more)
    // NOTE: We need to find space for at least the LFN + SFN (or just the SFN if LFNs not supported).
    if (!fatfs_find_free_dir_offset(fs, dirCluster, entryCount + 1, &dirSector, &dirOffset))
        return 0;

    // Generate checksum of short filename
    pSname = (uint8*)shortfilename;
    checksum = 0;
    for (i=11; i!=0; i--) checksum = ((checksum & 1) ? 0x80 : 0) + (checksum >> 1) + *pSname++;

    // Start from current sector where space was found!
    x = dirSector;

    // Main cluster following loop
    while (1)
    {
        // Read sector
        if (fatfs_sector_reader(fs, dirCluster, x++, 0))
        {
            // Analyse Sector
            for (item = 0; item < FAT_DIR_ENTRIES_PER_SECTOR; item++)
            {
                // Create the multiplier for sector access
                recordoffset = FAT_DIR_ENTRY_SIZE * item;

                // If the start position for the entry has been found
                if (foundEnd==0)
                    if ( (dirSector==(x-1)) && (dirOffset==item) )
                        foundEnd = 1;

                // Start adding filename
                if (foundEnd)
                {
                    if (entryCount==0)
                    {
                        // Short filename
                        fatfs_sfn_create_entry(shortfilename, size, startCluster, &shortEntry, dir);

#if FATFS_INC_TIME_DATE_SUPPORT
                        // Update create, access & modify time & date
                        fatfs_update_timestamps(&shortEntry, 1, 1, 1);
#endif

                        memcpy(&fs->currentsector.sector[recordoffset], &shortEntry, sizeof(shortEntry));

                        // Writeback
                        return fs->disk_io.write_media(fs->currentsector.address, fs->currentsector.sector, 1);
                    }
#if FATFS_INC_LFN_SUPPORT
                    else
                    {
                        entryCount--;

                        // Copy entry to directory buffer
                        fatfs_filename_to_lfn(filename, &fs->currentsector.sector[recordoffset], entryCount, checksum);
                        dirtySector = 1;
                    }
#endif
                }
            } // End of if

            // Write back to disk before loading another sector
            if (dirtySector)
            {
                if (!fs->disk_io.write_media(fs->currentsector.address, fs->currentsector.sector, 1))
                    return 0;

                dirtySector = 0;
            }
        }
        else
            return 0;
    } // End of while loop

    return 0;
}
#endif