Mercurial > pihelp
diff fat.c @ 19:5f9a40d6991b
Import SD handling from http://www.roland-riegel.de/sd-reader/index.html
Use smaller build options
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Tue, 25 Jun 2013 13:55:11 +0800 |
| parents | |
| children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/fat.c Tue Jun 25 13:55:11 2013 +0800 @@ -0,0 +1,2551 @@ + +/* + * Copyright (c) 2006-2012 by Roland Riegel <[email protected]> + * + * This file is free software; you can redistribute it and/or modify + * it under the terms of either the GNU General Public License version 2 + * or the GNU Lesser General Public License version 2.1, both as + * published by the Free Software Foundation. + */ + +#include "byteordering.h" +#include "partition.h" +#include "fat.h" +#include "fat_config.h" +#include "sd-reader_config.h" + +#include <string.h> + +#if USE_DYNAMIC_MEMORY + #include <stdlib.h> +#endif + +/** + * \addtogroup fat FAT support + * + * This module implements FAT16/FAT32 read and write access. + * + * The following features are supported: + * - File names up to 31 characters long. + * - Unlimited depth of subdirectories. + * - Short 8.3 and long filenames. + * - Creating and deleting files. + * - Reading and writing from and to files. + * - File resizing. + * - File sizes of up to 4 gigabytes. + * + * @{ + */ +/** + * \file + * FAT implementation (license: GPLv2 or LGPLv2.1) + * + * \author Roland Riegel + */ + +/** + * \addtogroup fat_config FAT configuration + * Preprocessor defines to configure the FAT implementation. + */ + +/** + * \addtogroup fat_fs FAT access + * Basic functions for handling a FAT filesystem. + */ + +/** + * \addtogroup fat_file FAT file functions + * Functions for managing files. + */ + +/** + * \addtogroup fat_dir FAT directory functions + * Functions for managing directories. + */ + +/** + * @} + */ + +#define FAT16_CLUSTER_FREE 0x0000 +#define FAT16_CLUSTER_RESERVED_MIN 0xfff0 +#define FAT16_CLUSTER_RESERVED_MAX 0xfff6 +#define FAT16_CLUSTER_BAD 0xfff7 +#define FAT16_CLUSTER_LAST_MIN 0xfff8 +#define FAT16_CLUSTER_LAST_MAX 0xffff + +#define FAT32_CLUSTER_FREE 0x00000000 +#define FAT32_CLUSTER_RESERVED_MIN 0x0ffffff0 +#define FAT32_CLUSTER_RESERVED_MAX 0x0ffffff6 +#define FAT32_CLUSTER_BAD 0x0ffffff7 +#define FAT32_CLUSTER_LAST_MIN 0x0ffffff8 +#define FAT32_CLUSTER_LAST_MAX 0x0fffffff + +#define FAT_DIRENTRY_DELETED 0xe5 +#define FAT_DIRENTRY_LFNLAST (1 << 6) +#define FAT_DIRENTRY_LFNSEQMASK ((1 << 6) - 1) + +/* Each entry within the directory table has a size of 32 bytes + * and either contains a 8.3 DOS-style file name or a part of a + * long file name, which may consist of several directory table + * entries at once. + * + * multi-byte integer values are stored little-endian! + * + * 8.3 file name entry: + * ==================== + * offset length description + * 0 8 name (space padded) + * 8 3 extension (space padded) + * 11 1 attributes (FAT_ATTRIB_*) + * + * long file name (lfn) entry ordering for a single file name: + * =========================================================== + * LFN entry n + * ... + * LFN entry 2 + * LFN entry 1 + * 8.3 entry (see above) + * + * lfn entry: + * ========== + * offset length description + * 0 1 ordinal field + * 1 2 unicode character 1 + * 3 3 unicode character 2 + * 5 3 unicode character 3 + * 7 3 unicode character 4 + * 9 3 unicode character 5 + * 11 1 attribute (always 0x0f) + * 12 1 type (reserved, always 0) + * 13 1 checksum + * 14 2 unicode character 6 + * 16 2 unicode character 7 + * 18 2 unicode character 8 + * 20 2 unicode character 9 + * 22 2 unicode character 10 + * 24 2 unicode character 11 + * 26 2 cluster (unused, always 0) + * 28 2 unicode character 12 + * 30 2 unicode character 13 + * + * The ordinal field contains a descending number, from n to 1. + * For the n'th lfn entry the ordinal field is or'ed with 0x40. + * For deleted lfn entries, the ordinal field is set to 0xe5. + */ + +struct fat_header_struct +{ + offset_t size; + + offset_t fat_offset; + uint32_t fat_size; + + uint16_t sector_size; + uint16_t cluster_size; + + offset_t cluster_zero_offset; + + offset_t root_dir_offset; +#if FAT_FAT32_SUPPORT + cluster_t root_dir_cluster; +#endif +}; + +struct fat_fs_struct +{ + struct partition_struct* partition; + struct fat_header_struct header; + cluster_t cluster_free; +}; + +struct fat_file_struct +{ + struct fat_fs_struct* fs; + struct fat_dir_entry_struct dir_entry; + offset_t pos; + cluster_t pos_cluster; +}; + +struct fat_dir_struct +{ + struct fat_fs_struct* fs; + struct fat_dir_entry_struct dir_entry; + cluster_t entry_cluster; + uint16_t entry_offset; +}; + +struct fat_read_dir_callback_arg +{ + struct fat_dir_entry_struct* dir_entry; + uintptr_t bytes_read; +#if FAT_LFN_SUPPORT + uint8_t checksum; +#endif + uint8_t finished; +}; + +struct fat_usage_count_callback_arg +{ + cluster_t cluster_count; + uintptr_t buffer_size; +}; + +#if !USE_DYNAMIC_MEMORY +static struct fat_fs_struct fat_fs_handles[FAT_FS_COUNT]; +static struct fat_file_struct fat_file_handles[FAT_FILE_COUNT]; +static struct fat_dir_struct fat_dir_handles[FAT_DIR_COUNT]; +#endif + +static uint8_t fat_read_header(struct fat_fs_struct* fs); +static cluster_t fat_get_next_cluster(const struct fat_fs_struct* fs, cluster_t cluster_num); +static offset_t fat_cluster_offset(const struct fat_fs_struct* fs, cluster_t cluster_num); +static uint8_t fat_dir_entry_read_callback(uint8_t* buffer, offset_t offset, void* p); +#if FAT_LFN_SUPPORT +static uint8_t fat_calc_83_checksum(const uint8_t* file_name_83); +#endif + +static uint8_t fat_get_fs_free_16_callback(uint8_t* buffer, offset_t offset, void* p); +#if FAT_FAT32_SUPPORT +static uint8_t fat_get_fs_free_32_callback(uint8_t* buffer, offset_t offset, void* p); +#endif + +#if FAT_WRITE_SUPPORT +static cluster_t fat_append_clusters(struct fat_fs_struct* fs, cluster_t cluster_num, cluster_t count); +static uint8_t fat_free_clusters(struct fat_fs_struct* fs, cluster_t cluster_num); +static uint8_t fat_terminate_clusters(struct fat_fs_struct* fs, cluster_t cluster_num); +static uint8_t fat_clear_cluster(const struct fat_fs_struct* fs, cluster_t cluster_num); +static uintptr_t fat_clear_cluster_callback(uint8_t* buffer, offset_t offset, void* p); +static offset_t fat_find_offset_for_dir_entry(struct fat_fs_struct* fs, const struct fat_dir_struct* parent, const struct fat_dir_entry_struct* dir_entry); +static uint8_t fat_write_dir_entry(const struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry); +#if FAT_DATETIME_SUPPORT +static void fat_set_file_modification_date(struct fat_dir_entry_struct* dir_entry, uint16_t year, uint8_t month, uint8_t day); +static void fat_set_file_modification_time(struct fat_dir_entry_struct* dir_entry, uint8_t hour, uint8_t min, uint8_t sec); +#endif +#endif + +/** + * \ingroup fat_fs + * Opens a FAT filesystem. + * + * \param[in] partition Discriptor of partition on which the filesystem resides. + * \returns 0 on error, a FAT filesystem descriptor on success. + * \see fat_close + */ +struct fat_fs_struct* fat_open(struct partition_struct* partition) +{ + if(!partition || +#if FAT_WRITE_SUPPORT + !partition->device_write || + !partition->device_write_interval +#else + 0 +#endif + ) + return 0; + +#if USE_DYNAMIC_MEMORY + struct fat_fs_struct* fs = malloc(sizeof(*fs)); + if(!fs) + return 0; +#else + struct fat_fs_struct* fs = fat_fs_handles; + uint8_t i; + for(i = 0; i < FAT_FS_COUNT; ++i) + { + if(!fs->partition) + break; + + ++fs; + } + if(i >= FAT_FS_COUNT) + return 0; +#endif + + memset(fs, 0, sizeof(*fs)); + + fs->partition = partition; + if(!fat_read_header(fs)) + { +#if USE_DYNAMIC_MEMORY + free(fs); +#else + fs->partition = 0; +#endif + return 0; + } + + return fs; +} + +/** + * \ingroup fat_fs + * Closes a FAT filesystem. + * + * When this function returns, the given filesystem descriptor + * will be invalid. + * + * \param[in] fs The filesystem to close. + * \see fat_open + */ +void fat_close(struct fat_fs_struct* fs) +{ + if(!fs) + return; + +#if USE_DYNAMIC_MEMORY + free(fs); +#else + fs->partition = 0; +#endif +} + +/** + * \ingroup fat_fs + * Reads and parses the header of a FAT filesystem. + * + * \param[in,out] fs The filesystem for which to parse the header. + * \returns 0 on failure, 1 on success. + */ +uint8_t fat_read_header(struct fat_fs_struct* fs) +{ + if(!fs) + return 0; + + struct partition_struct* partition = fs->partition; + if(!partition) + return 0; + + /* read fat parameters */ +#if FAT_FAT32_SUPPORT + uint8_t buffer[37]; +#else + uint8_t buffer[25]; +#endif + offset_t partition_offset = (offset_t) partition->offset * 512; + if(!partition->device_read(partition_offset + 0x0b, buffer, sizeof(buffer))) + return 0; + + uint16_t bytes_per_sector = read16(&buffer[0x00]); + uint16_t reserved_sectors = read16(&buffer[0x03]); + uint8_t sectors_per_cluster = buffer[0x02]; + uint8_t fat_copies = buffer[0x05]; + uint16_t max_root_entries = read16(&buffer[0x06]); + uint16_t sector_count_16 = read16(&buffer[0x08]); + uint16_t sectors_per_fat = read16(&buffer[0x0b]); + uint32_t sector_count = read32(&buffer[0x15]); +#if FAT_FAT32_SUPPORT + uint32_t sectors_per_fat32 = read32(&buffer[0x19]); + uint32_t cluster_root_dir = read32(&buffer[0x21]); +#endif + + if(sector_count == 0) + { + if(sector_count_16 == 0) + /* illegal volume size */ + return 0; + else + sector_count = sector_count_16; + } +#if FAT_FAT32_SUPPORT + if(sectors_per_fat != 0) + sectors_per_fat32 = sectors_per_fat; + else if(sectors_per_fat32 == 0) + /* this is neither FAT16 nor FAT32 */ + return 0; +#else + if(sectors_per_fat == 0) + /* this is not a FAT16 */ + return 0; +#endif + + /* determine the type of FAT we have here */ + uint32_t data_sector_count = sector_count + - reserved_sectors +#if FAT_FAT32_SUPPORT + - sectors_per_fat32 * fat_copies +#else + - (uint32_t) sectors_per_fat * fat_copies +#endif + - ((max_root_entries * 32 + bytes_per_sector - 1) / bytes_per_sector); + uint32_t data_cluster_count = data_sector_count / sectors_per_cluster; + if(data_cluster_count < 4085) + /* this is a FAT12, not supported */ + return 0; + else if(data_cluster_count < 65525) + /* this is a FAT16 */ + partition->type = PARTITION_TYPE_FAT16; + else + /* this is a FAT32 */ + partition->type = PARTITION_TYPE_FAT32; + + /* fill header information */ + struct fat_header_struct* header = &fs->header; + memset(header, 0, sizeof(*header)); + + header->size = (offset_t) sector_count * bytes_per_sector; + + header->fat_offset = /* jump to partition */ + partition_offset + + /* jump to fat */ + (offset_t) reserved_sectors * bytes_per_sector; + header->fat_size = (data_cluster_count + 2) * (partition->type == PARTITION_TYPE_FAT16 ? 2 : 4); + + header->sector_size = bytes_per_sector; + header->cluster_size = (uint16_t) bytes_per_sector * sectors_per_cluster; + +#if FAT_FAT32_SUPPORT + if(partition->type == PARTITION_TYPE_FAT16) +#endif + { + header->root_dir_offset = /* jump to fats */ + header->fat_offset + + /* jump to root directory entries */ + (offset_t) fat_copies * sectors_per_fat * bytes_per_sector; + + header->cluster_zero_offset = /* jump to root directory entries */ + header->root_dir_offset + + /* skip root directory entries */ + (offset_t) max_root_entries * 32; + } +#if FAT_FAT32_SUPPORT + else + { + header->cluster_zero_offset = /* jump to fats */ + header->fat_offset + + /* skip fats */ + (offset_t) fat_copies * sectors_per_fat32 * bytes_per_sector; + + header->root_dir_cluster = cluster_root_dir; + } +#endif + + return 1; +} + +/** + * \ingroup fat_fs + * Retrieves the next following cluster of a given cluster. + * + * Using the filesystem file allocation table, this function returns + * the number of the cluster containing the data directly following + * the data within the cluster with the given number. + * + * \param[in] fs The filesystem for which to determine the next cluster. + * \param[in] cluster_num The number of the cluster for which to determine its successor. + * \returns The wanted cluster number, or 0 on error. + */ +cluster_t fat_get_next_cluster(const struct fat_fs_struct* fs, cluster_t cluster_num) +{ + if(!fs || cluster_num < 2) + return 0; + +#if FAT_FAT32_SUPPORT + if(fs->partition->type == PARTITION_TYPE_FAT32) + { + /* read appropriate fat entry */ + uint32_t fat_entry; + if(!fs->partition->device_read(fs->header.fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry))) + return 0; + + /* determine next cluster from fat */ + cluster_num = ltoh32(fat_entry); + + if(cluster_num == FAT32_CLUSTER_FREE || + cluster_num == FAT32_CLUSTER_BAD || + (cluster_num >= FAT32_CLUSTER_RESERVED_MIN && cluster_num <= FAT32_CLUSTER_RESERVED_MAX) || + (cluster_num >= FAT32_CLUSTER_LAST_MIN && cluster_num <= FAT32_CLUSTER_LAST_MAX)) + return 0; + } + else +#endif + { + /* read appropriate fat entry */ + uint16_t fat_entry; + if(!fs->partition->device_read(fs->header.fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry))) + return 0; + + /* determine next cluster from fat */ + cluster_num = ltoh16(fat_entry); + + if(cluster_num == FAT16_CLUSTER_FREE || + cluster_num == FAT16_CLUSTER_BAD || + (cluster_num >= FAT16_CLUSTER_RESERVED_MIN && cluster_num <= FAT16_CLUSTER_RESERVED_MAX) || + (cluster_num >= FAT16_CLUSTER_LAST_MIN && cluster_num <= FAT16_CLUSTER_LAST_MAX)) + return 0; + } + + return cluster_num; +} + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_fs + * Appends a new cluster chain to an existing one. + * + * Set cluster_num to zero to create a completely new one. + * + * \param[in] fs The file system on which to operate. + * \param[in] cluster_num The cluster to which to append the new chain. + * \param[in] count The number of clusters to allocate. + * \returns 0 on failure, the number of the first new cluster on success. + */ +cluster_t fat_append_clusters(struct fat_fs_struct* fs, cluster_t cluster_num, cluster_t count) +{ + if(!fs) + return 0; + + device_read_t device_read = fs->partition->device_read; + device_write_t device_write = fs->partition->device_write; + offset_t fat_offset = fs->header.fat_offset; + cluster_t count_left = count; + cluster_t cluster_current = fs->cluster_free; + cluster_t cluster_next = 0; + cluster_t cluster_count; + uint16_t fat_entry16; +#if FAT_FAT32_SUPPORT + uint32_t fat_entry32; + uint8_t is_fat32 = (fs->partition->type == PARTITION_TYPE_FAT32); + + if(is_fat32) + cluster_count = fs->header.fat_size / sizeof(fat_entry32); + else +#endif + cluster_count = fs->header.fat_size / sizeof(fat_entry16); + + fs->cluster_free = 0; + for(cluster_t cluster_left = cluster_count; cluster_left > 0; --cluster_left, ++cluster_current) + { + if(cluster_current < 2 || cluster_current >= cluster_count) + cluster_current = 2; + +#if FAT_FAT32_SUPPORT + if(is_fat32) + { + if(!device_read(fat_offset + (offset_t) cluster_current * sizeof(fat_entry32), (uint8_t*) &fat_entry32, sizeof(fat_entry32))) + return 0; + } + else +#endif + { + if(!device_read(fat_offset + (offset_t) cluster_current * sizeof(fat_entry16), (uint8_t*) &fat_entry16, sizeof(fat_entry16))) + return 0; + } + +#if FAT_FAT32_SUPPORT + if(is_fat32) + { + /* check if this is a free cluster */ + if(fat_entry32 != HTOL32(FAT32_CLUSTER_FREE)) + continue; + + /* If we don't need this free cluster for the + * current allocation, we keep it in mind for + * the next time. + */ + if(count_left == 0) + { + fs->cluster_free = cluster_current; + break; + } + + /* allocate cluster */ + if(cluster_next == 0) + fat_entry32 = HTOL32(FAT32_CLUSTER_LAST_MAX); + else + fat_entry32 = htol32(cluster_next); + + if(!device_write(fat_offset + (offset_t) cluster_current * sizeof(fat_entry32), (uint8_t*) &fat_entry32, sizeof(fat_entry32))) + break; + } + else +#endif + { + /* check if this is a free cluster */ + if(fat_entry16 != HTOL16(FAT16_CLUSTER_FREE)) + continue; + + /* If we don't need this free cluster for the + * current allocation, we keep it in mind for + * the next time. + */ + if(count_left == 0) + { + fs->cluster_free = cluster_current; + break; + } + + /* allocate cluster */ + if(cluster_next == 0) + fat_entry16 = HTOL16(FAT16_CLUSTER_LAST_MAX); + else + fat_entry16 = htol16((uint16_t) cluster_next); + + if(!device_write(fat_offset + (offset_t) cluster_current * sizeof(fat_entry16), (uint8_t*) &fat_entry16, sizeof(fat_entry16))) + break; + } + + cluster_next = cluster_current; + --count_left; + } + + do + { + if(count_left > 0) + break; + + /* We allocated a new cluster chain. Now join + * it with the existing one (if any). + */ + if(cluster_num >= 2) + { +#if FAT_FAT32_SUPPORT + if(is_fat32) + { + fat_entry32 = htol32(cluster_next); + + if(!device_write(fat_offset + (offset_t) cluster_num * sizeof(fat_entry32), (uint8_t*) &fat_entry32, sizeof(fat_entry32))) + break; + } + else +#endif + { + fat_entry16 = htol16((uint16_t) cluster_next); + + if(!device_write(fat_offset + (offset_t) cluster_num * sizeof(fat_entry16), (uint8_t*) &fat_entry16, sizeof(fat_entry16))) + break; + } + } + + return cluster_next; + + } while(0); + + /* No space left on device or writing error. + * Free up all clusters already allocated. + */ + fat_free_clusters(fs, cluster_next); + + return 0; +} +#endif + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_fs + * Frees a cluster chain, or a part thereof. + * + * Marks the specified cluster and all clusters which are sequentially + * referenced by it as free. They may then be used again for future + * file allocations. + * + * \note If this function is used for freeing just a part of a cluster + * chain, the new end of the chain is not correctly terminated + * within the FAT. Use fat_terminate_clusters() instead. + * + * \param[in] fs The filesystem on which to operate. + * \param[in] cluster_num The starting cluster of the chain which to free. + * \returns 0 on failure, 1 on success. + * \see fat_terminate_clusters + */ +uint8_t fat_free_clusters(struct fat_fs_struct* fs, cluster_t cluster_num) +{ + if(!fs || cluster_num < 2) + return 0; + + offset_t fat_offset = fs->header.fat_offset; +#if FAT_FAT32_SUPPORT + if(fs->partition->type == PARTITION_TYPE_FAT32) + { + uint32_t fat_entry; + while(cluster_num) + { + if(!fs->partition->device_read(fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry))) + return 0; + + /* get next cluster of current cluster before freeing current cluster */ + uint32_t cluster_num_next = ltoh32(fat_entry); + + if(cluster_num_next == FAT32_CLUSTER_FREE) + return 1; + if(cluster_num_next == FAT32_CLUSTER_BAD || + (cluster_num_next >= FAT32_CLUSTER_RESERVED_MIN && + cluster_num_next <= FAT32_CLUSTER_RESERVED_MAX + ) + ) + return 0; + if(cluster_num_next >= FAT32_CLUSTER_LAST_MIN && cluster_num_next <= FAT32_CLUSTER_LAST_MAX) + cluster_num_next = 0; + + /* We know we will free the cluster, so remember it as + * free for the next allocation. + */ + if(!fs->cluster_free) + fs->cluster_free = cluster_num; + + /* free cluster */ + fat_entry = HTOL32(FAT32_CLUSTER_FREE); + fs->partition->device_write(fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry)); + + /* We continue in any case here, even if freeing the cluster failed. + * The cluster is lost, but maybe we can still free up some later ones. + */ + + cluster_num = cluster_num_next; + } + } + else +#endif + { + uint16_t fat_entry; + while(cluster_num) + { + if(!fs->partition->device_read(fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry))) + return 0; + + /* get next cluster of current cluster before freeing current cluster */ + uint16_t cluster_num_next = ltoh16(fat_entry); + + if(cluster_num_next == FAT16_CLUSTER_FREE) + return 1; + if(cluster_num_next == FAT16_CLUSTER_BAD || + (cluster_num_next >= FAT16_CLUSTER_RESERVED_MIN && + cluster_num_next <= FAT16_CLUSTER_RESERVED_MAX + ) + ) + return 0; + if(cluster_num_next >= FAT16_CLUSTER_LAST_MIN && cluster_num_next <= FAT16_CLUSTER_LAST_MAX) + cluster_num_next = 0; + + /* free cluster */ + fat_entry = HTOL16(FAT16_CLUSTER_FREE); + fs->partition->device_write(fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry)); + + /* We continue in any case here, even if freeing the cluster failed. + * The cluster is lost, but maybe we can still free up some later ones. + */ + + cluster_num = cluster_num_next; + } + } + + return 1; +} +#endif + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_fs + * Frees a part of a cluster chain and correctly terminates the rest. + * + * Marks the specified cluster as the new end of a cluster chain and + * frees all following clusters. + * + * \param[in] fs The filesystem on which to operate. + * \param[in] cluster_num The new end of the cluster chain. + * \returns 0 on failure, 1 on success. + * \see fat_free_clusters + */ +uint8_t fat_terminate_clusters(struct fat_fs_struct* fs, cluster_t cluster_num) +{ + if(!fs || cluster_num < 2) + return 0; + + /* fetch next cluster before overwriting the cluster entry */ + cluster_t cluster_num_next = fat_get_next_cluster(fs, cluster_num); + + /* mark cluster as the last one */ +#if FAT_FAT32_SUPPORT + if(fs->partition->type == PARTITION_TYPE_FAT32) + { + uint32_t fat_entry = HTOL32(FAT32_CLUSTER_LAST_MAX); + if(!fs->partition->device_write(fs->header.fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry))) + return 0; + } + else +#endif + { + uint16_t fat_entry = HTOL16(FAT16_CLUSTER_LAST_MAX); + if(!fs->partition->device_write(fs->header.fat_offset + (offset_t) cluster_num * sizeof(fat_entry), (uint8_t*) &fat_entry, sizeof(fat_entry))) + return 0; + } + + /* free remaining clusters */ + if(cluster_num_next) + return fat_free_clusters(fs, cluster_num_next); + else + return 1; +} +#endif + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_fs + * Clears a single cluster. + * + * The complete cluster is filled with zeros. + * + * \param[in] fs The filesystem on which to operate. + * \param[in] cluster_num The cluster to clear. + * \returns 0 on failure, 1 on success. + */ +uint8_t fat_clear_cluster(const struct fat_fs_struct* fs, cluster_t cluster_num) +{ + if(cluster_num < 2) + return 0; + + offset_t cluster_offset = fat_cluster_offset(fs, cluster_num); + + uint8_t zero[16]; + memset(zero, 0, sizeof(zero)); + return fs->partition->device_write_interval(cluster_offset, + zero, + fs->header.cluster_size, + fat_clear_cluster_callback, + 0 + ); +} +#endif + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_fs + * Callback function for clearing a cluster. + */ +uintptr_t fat_clear_cluster_callback(uint8_t* buffer, offset_t offset, void* p) +{ + return 16; +} +#endif + +/** + * \ingroup fat_fs + * Calculates the offset of the specified cluster. + * + * \param[in] fs The filesystem on which to operate. + * \param[in] cluster_num The cluster whose offset to calculate. + * \returns The cluster offset. + */ +offset_t fat_cluster_offset(const struct fat_fs_struct* fs, cluster_t cluster_num) +{ + if(!fs || cluster_num < 2) + return 0; + + return fs->header.cluster_zero_offset + (offset_t) (cluster_num - 2) * fs->header.cluster_size; +} + +/** + * \ingroup fat_file + * Retrieves the directory entry of a path. + * + * The given path may both describe a file or a directory. + * + * \param[in] fs The FAT filesystem on which to search. + * \param[in] path The path of which to read the directory entry. + * \param[out] dir_entry The directory entry to fill. + * \returns 0 on failure, 1 on success. + * \see fat_read_dir + */ +uint8_t fat_get_dir_entry_of_path(struct fat_fs_struct* fs, const char* path, struct fat_dir_entry_struct* dir_entry) +{ + if(!fs || !path || path[0] == '\0' || !dir_entry) + return 0; + + if(path[0] == '/') + ++path; + + /* begin with the root directory */ + memset(dir_entry, 0, sizeof(*dir_entry)); + dir_entry->attributes = FAT_ATTRIB_DIR; + + while(1) + { + if(path[0] == '\0') + return 1; + + struct fat_dir_struct* dd = fat_open_dir(fs, dir_entry); + if(!dd) + break; + + /* extract the next hierarchy we will search for */ + const char* sub_path = strchr(path, '/'); + uint8_t length_to_sep; + if(sub_path) + { + length_to_sep = sub_path - path; + ++sub_path; + } + else + { + length_to_sep = strlen(path); + sub_path = path + length_to_sep; + } + + /* read directory entries */ + while(fat_read_dir(dd, dir_entry)) + { + /* check if we have found the next hierarchy */ + if((strlen(dir_entry->long_name) != length_to_sep || + strncmp(path, dir_entry->long_name, length_to_sep) != 0)) + continue; + + fat_close_dir(dd); + dd = 0; + + if(path[length_to_sep] == '\0') + /* we iterated through the whole path and have found the file */ + return 1; + + if(dir_entry->attributes & FAT_ATTRIB_DIR) + { + /* we found a parent directory of the file we are searching for */ + path = sub_path; + break; + } + + /* a parent of the file exists, but not the file itself */ + return 0; + } + + fat_close_dir(dd); + } + + return 0; +} + +/** + * \ingroup fat_file + * Opens a file on a FAT filesystem. + * + * \param[in] fs The filesystem on which the file to open lies. + * \param[in] dir_entry The directory entry of the file to open. + * \returns The file handle, or 0 on failure. + * \see fat_close_file + */ +struct fat_file_struct* fat_open_file(struct fat_fs_struct* fs, const struct fat_dir_entry_struct* dir_entry) +{ + if(!fs || !dir_entry || (dir_entry->attributes & FAT_ATTRIB_DIR)) + return 0; + +#if USE_DYNAMIC_MEMORY + struct fat_file_struct* fd = malloc(sizeof(*fd)); + if(!fd) + return 0; +#else + struct fat_file_struct* fd = fat_file_handles; + uint8_t i; + for(i = 0; i < FAT_FILE_COUNT; ++i) + { + if(!fd->fs) + break; + + ++fd; + } + if(i >= FAT_FILE_COUNT) + return 0; +#endif + + memcpy(&fd->dir_entry, dir_entry, sizeof(*dir_entry)); + fd->fs = fs; + fd->pos = 0; + fd->pos_cluster = dir_entry->cluster; + + return fd; +} + +/** + * \ingroup fat_file + * Closes a file. + * + * \param[in] fd The file handle of the file to close. + * \see fat_open_file + */ +void fat_close_file(struct fat_file_struct* fd) +{ + if(fd) + { +#if FAT_DELAY_DIRENTRY_UPDATE + /* write directory entry */ + fat_write_dir_entry(fd->fs, &fd->dir_entry); +#endif + +#if USE_DYNAMIC_MEMORY + free(fd); +#else + fd->fs = 0; +#endif + } +} + +/** + * \ingroup fat_file + * Reads data from a file. + * + * The data requested is read from the current file location. + * + * \param[in] fd The file handle of the file from which to read. + * \param[out] buffer The buffer into which to write. + * \param[in] buffer_len The amount of data to read. + * \returns The number of bytes read, 0 on end of file, or -1 on failure. + * \see fat_write_file + */ +intptr_t fat_read_file(struct fat_file_struct* fd, uint8_t* buffer, uintptr_t buffer_len) +{ + /* check arguments */ + if(!fd || !buffer || buffer_len < 1) + return -1; + + /* determine number of bytes to read */ + if(fd->pos + buffer_len > fd->dir_entry.file_size) + buffer_len = fd->dir_entry.file_size - fd->pos; + if(buffer_len == 0) + return 0; + + uint16_t cluster_size = fd->fs->header.cluster_size; + cluster_t cluster_num = fd->pos_cluster; + uintptr_t buffer_left = buffer_len; + uint16_t first_cluster_offset = (uint16_t) (fd->pos & (cluster_size - 1)); + + /* find cluster in which to start reading */ + if(!cluster_num) + { + cluster_num = fd->dir_entry.cluster; + + if(!cluster_num) + { + if(!fd->pos) + return 0; + else + return -1; + } + + if(fd->pos) + { + uint32_t pos = fd->pos; + while(pos >= cluster_size) + { + pos -= cluster_size; + cluster_num = fat_get_next_cluster(fd->fs, cluster_num); + if(!cluster_num) + return -1; + } + } + } + + /* read data */ + do + { + /* calculate data size to copy from cluster */ + offset_t cluster_offset = fat_cluster_offset(fd->fs, cluster_num) + first_cluster_offset; + uint16_t copy_length = cluster_size - first_cluster_offset; + if(copy_length > buffer_left) + copy_length = buffer_left; + + /* read data */ + if(!fd->fs->partition->device_read(cluster_offset, buffer, copy_length)) + return buffer_len - buffer_left; + + /* calculate new file position */ + buffer += copy_length; + buffer_left -= copy_length; + fd->pos += copy_length; + + if(first_cluster_offset + copy_length >= cluster_size) + { + /* we are on a cluster boundary, so get the next cluster */ + if((cluster_num = fat_get_next_cluster(fd->fs, cluster_num))) + { + first_cluster_offset = 0; + } + else + { + fd->pos_cluster = 0; + return buffer_len - buffer_left; + } + } + + fd->pos_cluster = cluster_num; + + } while(buffer_left > 0); /* check if we are done */ + + return buffer_len; +} + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_file + * Writes data to a file. + * + * The data is written to the current file location. + * + * \param[in] fd The file handle of the file to which to write. + * \param[in] buffer The buffer from which to read the data to be written. + * \param[in] buffer_len The amount of data to write. + * \returns The number of bytes written (0 or something less than \c buffer_len on disk full) or -1 on failure. + * \see fat_read_file + */ +intptr_t fat_write_file(struct fat_file_struct* fd, const uint8_t* buffer, uintptr_t buffer_len) +{ + /* check arguments */ + if(!fd || !buffer || buffer_len < 1) + return -1; + if(fd->pos > fd->dir_entry.file_size) + return -1; + + uint16_t cluster_size = fd->fs->header.cluster_size; + cluster_t cluster_num = fd->pos_cluster; + uintptr_t buffer_left = buffer_len; + uint16_t first_cluster_offset = (uint16_t) (fd->pos & (cluster_size - 1)); + + /* find cluster in which to start writing */ + if(!cluster_num) + { + cluster_num = fd->dir_entry.cluster; + + if(!cluster_num) + { + if(!fd->pos) + { + /* empty file */ + fd->dir_entry.cluster = cluster_num = fat_append_clusters(fd->fs, 0, 1); + if(!cluster_num) + return 0; + } + else + { + return -1; + } + } + + if(fd->pos) + { + uint32_t pos = fd->pos; + cluster_t cluster_num_next; + while(pos >= cluster_size) + { + pos -= cluster_size; + cluster_num_next = fat_get_next_cluster(fd->fs, cluster_num); + if(!cluster_num_next) + { + if(pos != 0) + return -1; /* current file position points beyond end of file */ + + /* the file exactly ends on a cluster boundary, and we append to it */ + cluster_num_next = fat_append_clusters(fd->fs, cluster_num, 1); + if(!cluster_num_next) + return 0; + } + + cluster_num = cluster_num_next; + } + } + } + + /* write data */ + do + { + /* calculate data size to write to cluster */ + offset_t cluster_offset = fat_cluster_offset(fd->fs, cluster_num) + first_cluster_offset; + uint16_t write_length = cluster_size - first_cluster_offset; + if(write_length > buffer_left) + write_length = buffer_left; + + /* write data which fits into the current cluster */ + if(!fd->fs->partition->device_write(cluster_offset, buffer, write_length)) + break; + + /* calculate new file position */ + buffer += write_length; + buffer_left -= write_length; + fd->pos += write_length; + + if(first_cluster_offset + write_length >= cluster_size) + { + /* we are on a cluster boundary, so get the next cluster */ + cluster_t cluster_num_next = fat_get_next_cluster(fd->fs, cluster_num); + if(!cluster_num_next && buffer_left > 0) + /* we reached the last cluster, append a new one */ + cluster_num_next = fat_append_clusters(fd->fs, cluster_num, 1); + if(!cluster_num_next) + { + fd->pos_cluster = 0; + break; + } + + cluster_num = cluster_num_next; + first_cluster_offset = 0; + } + + fd->pos_cluster = cluster_num; + + } while(buffer_left > 0); /* check if we are done */ + + /* update directory entry */ + if(fd->pos > fd->dir_entry.file_size) + { +#if !FAT_DELAY_DIRENTRY_UPDATE + uint32_t size_old = fd->dir_entry.file_size; +#endif + + /* update file size */ + fd->dir_entry.file_size = fd->pos; + +#if !FAT_DELAY_DIRENTRY_UPDATE + /* write directory entry */ + if(!fat_write_dir_entry(fd->fs, &fd->dir_entry)) + { + /* We do not return an error here since we actually wrote + * some data to disk. So we calculate the amount of data + * we wrote to disk and which lies within the old file size. + */ + buffer_left = fd->pos - size_old; + fd->pos = size_old; + } +#endif + } + + return buffer_len - buffer_left; +} +#endif + +/** + * \ingroup fat_file + * Repositions the read/write file offset. + * + * Changes the file offset where the next call to fat_read_file() + * or fat_write_file() starts reading/writing. + * + * If the new offset is beyond the end of the file, fat_resize_file() + * is implicitly called, i.e. the file is expanded. + * + * The new offset can be given in different ways determined by + * the \c whence parameter: + * - \b FAT_SEEK_SET: \c *offset is relative to the beginning of the file. + * - \b FAT_SEEK_CUR: \c *offset is relative to the current file position. + * - \b FAT_SEEK_END: \c *offset is relative to the end of the file. + * + * The resulting absolute offset is written to the location the \c offset + * parameter points to. + * + * Calling this function can also be used to retrieve the current file position: + \code + int32_t file_pos = 0; + if(!fat_seek_file(fd, &file_pos, FAT_SEEK_CUR)) + { + // error + } + // file_pos now contains the absolute file position + \endcode + * + * \param[in] fd The file decriptor of the file on which to seek. + * \param[in,out] offset A pointer to the new offset, as affected by the \c whence + * parameter. The function writes the new absolute offset + * to this location before it returns. + * \param[in] whence Affects the way \c offset is interpreted, see above. + * \returns 0 on failure, 1 on success. + */ +uint8_t fat_seek_file(struct fat_file_struct* fd, int32_t* offset, uint8_t whence) +{ + if(!fd || !offset) + return 0; + + uint32_t new_pos = fd->pos; + switch(whence) + { + case FAT_SEEK_SET: + new_pos = *offset; + break; + case FAT_SEEK_CUR: + new_pos += *offset; + break; + case FAT_SEEK_END: + new_pos = fd->dir_entry.file_size + *offset; + break; + default: + return 0; + } + + if(new_pos > fd->dir_entry.file_size +#if FAT_WRITE_SUPPORT + && !fat_resize_file(fd, new_pos) +#endif + ) + return 0; + + fd->pos = new_pos; + fd->pos_cluster = 0; + + *offset = (int32_t) new_pos; + return 1; +} + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_file + * Resizes a file to have a specific size. + * + * Enlarges or shrinks the file pointed to by the file descriptor to have + * exactly the specified size. + * + * If the file is truncated, all bytes having an equal or larger offset + * than the given size are lost. If the file is expanded, the additional + * bytes are allocated. + * + * \note Please be aware that this function just allocates or deallocates disk + * space, it does not explicitely clear it. To avoid data leakage, this + * must be done manually. + * + * \param[in] fd The file decriptor of the file which to resize. + * \param[in] size The new size of the file. + * \returns 0 on failure, 1 on success. + */ +uint8_t fat_resize_file(struct fat_file_struct* fd, uint32_t size) +{ + if(!fd) + return 0; + + cluster_t cluster_num = fd->dir_entry.cluster; + uint16_t cluster_size = fd->fs->header.cluster_size; + uint32_t size_new = size; + + do + { + if(cluster_num == 0 && size_new == 0) + /* the file stays empty */ + break; + + /* seek to the next cluster as long as we need the space */ + while(size_new > cluster_size) + { + /* get next cluster of file */ + cluster_t cluster_num_next = fat_get_next_cluster(fd->fs, cluster_num); + if(cluster_num_next) + { + cluster_num = cluster_num_next; + size_new -= cluster_size; + } + else + { + break; + } + } + + if(size_new > cluster_size || cluster_num == 0) + { + /* Allocate new cluster chain and append + * it to the existing one, if available. + */ + cluster_t cluster_count = (size_new + cluster_size - 1) / cluster_size; + cluster_t cluster_new_chain = fat_append_clusters(fd->fs, cluster_num, cluster_count); + if(!cluster_new_chain) + return 0; + + if(!cluster_num) + { + cluster_num = cluster_new_chain; + fd->dir_entry.cluster = cluster_num; + } + } + + /* write new directory entry */ + fd->dir_entry.file_size = size; + if(size == 0) + fd->dir_entry.cluster = 0; + if(!fat_write_dir_entry(fd->fs, &fd->dir_entry)) + return 0; + + if(size == 0) + { + /* free all clusters of file */ + fat_free_clusters(fd->fs, cluster_num); + } + else if(size_new <= cluster_size) + { + /* free all clusters no longer needed */ + fat_terminate_clusters(fd->fs, cluster_num); + } + + } while(0); + + /* correct file position */ + if(size < fd->pos) + { + fd->pos = size; + fd->pos_cluster = 0; + } + + return 1; +} +#endif + +/** + * \ingroup fat_dir + * Opens a directory. + * + * \param[in] fs The filesystem on which the directory to open resides. + * \param[in] dir_entry The directory entry which stands for the directory to open. + * \returns An opaque directory descriptor on success, 0 on failure. + * \see fat_close_dir + */ +struct fat_dir_struct* fat_open_dir(struct fat_fs_struct* fs, const struct fat_dir_entry_struct* dir_entry) +{ + if(!fs || !dir_entry || !(dir_entry->attributes & FAT_ATTRIB_DIR)) + return 0; + +#if USE_DYNAMIC_MEMORY + struct fat_dir_struct* dd = malloc(sizeof(*dd)); + if(!dd) + return 0; +#else + struct fat_dir_struct* dd = fat_dir_handles; + uint8_t i; + for(i = 0; i < FAT_DIR_COUNT; ++i) + { + if(!dd->fs) + break; + + ++dd; + } + if(i >= FAT_DIR_COUNT) + return 0; +#endif + + memcpy(&dd->dir_entry, dir_entry, sizeof(*dir_entry)); + dd->fs = fs; + dd->entry_cluster = dir_entry->cluster; + dd->entry_offset = 0; + + return dd; +} + +/** + * \ingroup fat_dir + * Closes a directory descriptor. + * + * This function destroys a directory descriptor which was + * previously obtained by calling fat_open_dir(). When this + * function returns, the given descriptor will be invalid. + * + * \param[in] dd The directory descriptor to close. + * \see fat_open_dir + */ +void fat_close_dir(struct fat_dir_struct* dd) +{ + if(dd) +#if USE_DYNAMIC_MEMORY + free(dd); +#else + dd->fs = 0; +#endif +} + +/** + * \ingroup fat_dir + * Reads the next directory entry contained within a parent directory. + * + * \param[in] dd The descriptor of the parent directory from which to read the entry. + * \param[out] dir_entry Pointer to a buffer into which to write the directory entry information. + * \returns 0 on failure, 1 on success. + * \see fat_reset_dir + */ +uint8_t fat_read_dir(struct fat_dir_struct* dd, struct fat_dir_entry_struct* dir_entry) +{ + if(!dd || !dir_entry) + return 0; + + /* get current position of directory handle */ + struct fat_fs_struct* fs = dd->fs; + const struct fat_header_struct* header = &fs->header; + uint16_t cluster_size = header->cluster_size; + cluster_t cluster_num = dd->entry_cluster; + uint16_t cluster_offset = dd->entry_offset; + struct fat_read_dir_callback_arg arg; + + if(cluster_offset >= cluster_size) + { + /* The latest call hit the border of the last cluster in + * the chain, but it still returned a directory entry. + * So we now reset the handle and signal the caller the + * end of the listing. + */ + fat_reset_dir(dd); + return 0; + } + + /* reset callback arguments */ + memset(&arg, 0, sizeof(arg)); + memset(dir_entry, 0, sizeof(*dir_entry)); + arg.dir_entry = dir_entry; + + /* check if we read from the root directory */ + if(cluster_num == 0) + { +#if FAT_FAT32_SUPPORT + if(fs->partition->type == PARTITION_TYPE_FAT32) + cluster_num = header->root_dir_cluster; + else +#endif + cluster_size = header->cluster_zero_offset - header->root_dir_offset; + } + + /* read entries */ + uint8_t buffer[32]; + while(!arg.finished) + { + /* read directory entries up to the cluster border */ + uint16_t cluster_left = cluster_size - cluster_offset; + offset_t pos = cluster_offset; + if(cluster_num == 0) + pos += header->root_dir_offset; + else + pos += fat_cluster_offset(fs, cluster_num); + + arg.bytes_read = 0; + if(!fs->partition->device_read_interval(pos, + buffer, + sizeof(buffer), + cluster_left, + fat_dir_entry_read_callback, + &arg) + ) + return 0; + + cluster_offset += arg.bytes_read; + + if(cluster_offset >= cluster_size) + { + /* we reached the cluster border and switch to the next cluster */ + + /* get number of next cluster */ + if((cluster_num = fat_get_next_cluster(fs, cluster_num)) != 0) + { + cluster_offset = 0; + continue; + } + + /* we are at the end of the cluster chain */ + if(!arg.finished) + { + /* directory entry not found, reset directory handle */ + fat_reset_dir(dd); + return 0; + } + else + { + /* The current execution of the function has been successful, + * so we can not signal an end of the directory listing to + * the caller, but must wait for the next call. So we keep an + * invalid cluster offset to mark this directory handle's + * traversal as finished. + */ + } + + break; + } + } + + dd->entry_cluster = cluster_num; + dd->entry_offset = cluster_offset; + + return arg.finished; +} + +/** + * \ingroup fat_dir + * Resets a directory handle. + * + * Resets the directory handle such that reading restarts + * with the first directory entry. + * + * \param[in] dd The directory handle to reset. + * \returns 0 on failure, 1 on success. + * \see fat_read_dir + */ +uint8_t fat_reset_dir(struct fat_dir_struct* dd) +{ + if(!dd) + return 0; + + dd->entry_cluster = dd->dir_entry.cluster; + dd->entry_offset = 0; + return 1; +} + +/** + * \ingroup fat_fs + * Callback function for reading a directory entry. + * + * Interprets a raw directory entry and puts the contained + * information into a fat_dir_entry_struct structure. + * + * For a single file there may exist multiple directory + * entries. All except the last one are lfn entries, which + * contain parts of the long filename. The last directory + * entry is a traditional 8.3 style one. It contains all + * other information like size, cluster, date and time. + * + * \param[in] buffer A pointer to 32 bytes of raw data. + * \param[in] offset The absolute offset of the raw data. + * \param[in,out] p An argument structure controlling operation. + * \returns 0 on failure or completion, 1 if reading has + * to be continued + */ +uint8_t fat_dir_entry_read_callback(uint8_t* buffer, offset_t offset, void* p) +{ + struct fat_read_dir_callback_arg* arg = p; + struct fat_dir_entry_struct* dir_entry = arg->dir_entry; + + arg->bytes_read += 32; + + /* skip deleted or empty entries */ + if(buffer[0] == FAT_DIRENTRY_DELETED || !buffer[0]) + { +#if FAT_LFN_SUPPORT + arg->checksum = 0; +#endif + return 1; + } + +#if !FAT_LFN_SUPPORT + /* skip lfn entries */ + if(buffer[11] == 0x0f) + return 1; +#endif + + char* long_name = dir_entry->long_name; +#if FAT_LFN_SUPPORT + if(buffer[11] == 0x0f) + { + /* checksum validation */ + if(arg->checksum == 0 || arg->checksum != buffer[13]) + { + /* reset directory entry */ + memset(dir_entry, 0, sizeof(*dir_entry)); + + arg->checksum = buffer[13]; + dir_entry->entry_offset = offset; + } + + /* lfn supports unicode, but we do not, for now. + * So we assume pure ascii and read only every + * second byte. + */ + uint16_t char_offset = ((buffer[0] & 0x3f) - 1) * 13; + const uint8_t char_mapping[] = { 1, 3, 5, 7, 9, 14, 16, 18, 20, 22, 24, 28, 30 }; + for(uint8_t i = 0; i <= 12 && char_offset + i < sizeof(dir_entry->long_name) - 1; ++i) + long_name[char_offset + i] = buffer[char_mapping[i]]; + + return 1; + } + else +#endif + { +#if FAT_LFN_SUPPORT + /* if we do not have a long name or the previous lfn does not match, take the 8.3 name */ + if(long_name[0] == '\0' || arg->checksum != fat_calc_83_checksum(buffer)) +#endif + { + /* reset directory entry */ + memset(dir_entry, 0, sizeof(*dir_entry)); + dir_entry->entry_offset = offset; + + uint8_t i; + for(i = 0; i < 8; ++i) + { + if(buffer[i] == ' ') + break; + long_name[i] = buffer[i]; + + /* Windows NT and later versions do not store lfn entries + * for 8.3 names which have a lowercase basename, extension + * or both when everything else is uppercase. They use two + * extra bits to signal a lowercase basename or extension. + */ + if((buffer[12] & 0x08) && buffer[i] >= 'A' && buffer[i] <= 'Z') + long_name[i] += 'a' - 'A'; + } + if(long_name[0] == 0x05) + long_name[0] = (char) FAT_DIRENTRY_DELETED; + + if(buffer[8] != ' ') + { + long_name[i++] = '.'; + + uint8_t j = 8; + for(; j < 11; ++j) + { + if(buffer[j] == ' ') + break; + long_name[i] = buffer[j]; + + /* See above for the lowercase 8.3 name handling of + * Windows NT and later. + */ + if((buffer[12] & 0x10) && buffer[j] >= 'A' && buffer[j] <= 'Z') + long_name[i] += 'a' - 'A'; + + ++i; + } + } + + long_name[i] = '\0'; + } + + /* extract properties of file and store them within the structure */ + dir_entry->attributes = buffer[11]; + dir_entry->cluster = read16(&buffer[26]); +#if FAT_FAT32_SUPPORT + dir_entry->cluster |= ((cluster_t) read16(&buffer[20])) << 16; +#endif + dir_entry->file_size = read32(&buffer[28]); + +#if FAT_DATETIME_SUPPORT + dir_entry->modification_time = read16(&buffer[22]); + dir_entry->modification_date = read16(&buffer[24]); +#endif + + arg->finished = 1; + return 0; + } +} + +#if DOXYGEN || FAT_LFN_SUPPORT +/** + * \ingroup fat_fs + * Calculates the checksum for 8.3 names used within the + * corresponding lfn directory entries. + * + * \param[in] file_name_83 The 11-byte file name buffer. + * \returns The checksum of the given file name. + */ +uint8_t fat_calc_83_checksum(const uint8_t* file_name_83) +{ + uint8_t checksum = file_name_83[0]; + for(uint8_t i = 1; i < 11; ++i) + checksum = ((checksum >> 1) | (checksum << 7)) + file_name_83[i]; + + return checksum; +} +#endif + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_fs + * Searches for space where to store a directory entry. + * + * \param[in] fs The filesystem on which to operate. + * \param[in] parent The directory in which to search. + * \param[in] dir_entry The directory entry for which to search space. + * \returns 0 on failure, a device offset on success. + */ +offset_t fat_find_offset_for_dir_entry(struct fat_fs_struct* fs, const struct fat_dir_struct* parent, const struct fat_dir_entry_struct* dir_entry) +{ + if(!fs || !dir_entry) + return 0; + + /* search for a place where to write the directory entry to disk */ +#if FAT_LFN_SUPPORT + uint8_t free_dir_entries_needed = (strlen(dir_entry->long_name) + 12) / 13 + 1; + uint8_t free_dir_entries_found = 0; +#endif + cluster_t cluster_num = parent->dir_entry.cluster; + offset_t dir_entry_offset = 0; + offset_t offset = 0; + offset_t offset_to = 0; +#if FAT_FAT32_SUPPORT + uint8_t is_fat32 = (fs->partition->type == PARTITION_TYPE_FAT32); +#endif + + if(cluster_num == 0) + { +#if FAT_FAT32_SUPPORT + if(is_fat32) + { + cluster_num = fs->header.root_dir_cluster; + } + else +#endif + { + /* we read/write from the root directory entry */ + offset = fs->header.root_dir_offset; + offset_to = fs->header.cluster_zero_offset; + dir_entry_offset = offset; + } + } + + while(1) + { + if(offset == offset_to) + { + if(cluster_num == 0) + /* We iterated through the whole root directory and + * could not find enough space for the directory entry. + */ + return 0; + + if(offset) + { + /* We reached a cluster boundary and have to + * switch to the next cluster. + */ + + cluster_t cluster_next = fat_get_next_cluster(fs, cluster_num); + if(!cluster_next) + { + cluster_next = fat_append_clusters(fs, cluster_num, 1); + if(!cluster_next) + return 0; + + /* we appended a new cluster and know it is free */ + dir_entry_offset = fs->header.cluster_zero_offset + + (offset_t) (cluster_next - 2) * fs->header.cluster_size; + + /* clear cluster to avoid garbage directory entries */ + fat_clear_cluster(fs, cluster_next); + + break; + } + cluster_num = cluster_next; + } + + offset = fat_cluster_offset(fs, cluster_num); + offset_to = offset + fs->header.cluster_size; + dir_entry_offset = offset; +#if FAT_LFN_SUPPORT + free_dir_entries_found = 0; +#endif + } + + /* read next lfn or 8.3 entry */ + uint8_t first_char; + if(!fs->partition->device_read(offset, &first_char, sizeof(first_char))) + return 0; + + /* check if we found a free directory entry */ + if(first_char == FAT_DIRENTRY_DELETED || !first_char) + { + /* check if we have the needed number of available entries */ +#if FAT_LFN_SUPPORT + ++free_dir_entries_found; + if(free_dir_entries_found >= free_dir_entries_needed) +#endif + break; + + offset += 32; + } + else + { + offset += 32; + dir_entry_offset = offset; +#if FAT_LFN_SUPPORT + free_dir_entries_found = 0; +#endif + } + } + + return dir_entry_offset; +} +#endif + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_fs + * Writes a directory entry to disk. + * + * \note The file name is not checked for invalid characters. + * + * \note The generation of the short 8.3 file name is quite + * simple. The first eight characters are used for the filename. + * The extension, if any, is made up of the first three characters + * following the last dot within the long filename. If the + * filename (without the extension) is longer than eight characters, + * the lower byte of the cluster number replaces the last two + * characters to avoid name clashes. In any other case, it is your + * responsibility to avoid name clashes. + * + * \param[in] fs The filesystem on which to operate. + * \param[in] dir_entry The directory entry to write. + * \returns 0 on failure, 1 on success. + */ +uint8_t fat_write_dir_entry(const struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry) +{ + if(!fs || !dir_entry) + return 0; + +#if FAT_DATETIME_SUPPORT + { + uint16_t year; + uint8_t month; + uint8_t day; + uint8_t hour; + uint8_t min; + uint8_t sec; + + fat_get_datetime(&year, &month, &day, &hour, &min, &sec); + fat_set_file_modification_date(dir_entry, year, month, day); + fat_set_file_modification_time(dir_entry, hour, min, sec); + } +#endif + + device_write_t device_write = fs->partition->device_write; + offset_t offset = dir_entry->entry_offset; + const char* name = dir_entry->long_name; + uint8_t name_len = strlen(name); +#if FAT_LFN_SUPPORT + uint8_t lfn_entry_count = (name_len + 12) / 13; +#endif + uint8_t buffer[32]; + + /* write 8.3 entry */ + + /* generate 8.3 file name */ + memset(&buffer[0], ' ', 11); + char* name_ext = strrchr(name, '.'); + if(name_ext && *++name_ext) + { + uint8_t name_ext_len = strlen(name_ext); + name_len -= name_ext_len + 1; + + if(name_ext_len > 3) +#if FAT_LFN_SUPPORT + name_ext_len = 3; +#else + return 0; +#endif + + memcpy(&buffer[8], name_ext, name_ext_len); + } + + if(name_len <= 8) + { + memcpy(buffer, name, name_len); + +#if FAT_LFN_SUPPORT + /* For now, we create lfn entries for all files, + * except the "." and ".." directory references. + * This is to avoid difficulties with capitalization, + * as 8.3 filenames allow uppercase letters only. + * + * Theoretically it would be possible to leave + * the 8.3 entry alone if the basename and the + * extension have no mixed capitalization. + */ + if(name[0] == '.' && + ((name[1] == '.' && name[2] == '\0') || + name[1] == '\0') + ) + lfn_entry_count = 0; +#endif + } + else + { +#if FAT_LFN_SUPPORT + memcpy(buffer, name, 8); + + /* Minimize 8.3 name clashes by appending + * the lower byte of the cluster number. + */ + uint8_t num = dir_entry->cluster & 0xff; + + buffer[6] = (num < 0xa0) ? ('0' + (num >> 4)) : ('a' + (num >> 4)); + num &= 0x0f; + buffer[7] = (num < 0x0a) ? ('0' + num) : ('a' + num); +#else + return 0; +#endif + } + if(buffer[0] == FAT_DIRENTRY_DELETED) + buffer[0] = 0x05; + + /* fill directory entry buffer */ + memset(&buffer[11], 0, sizeof(buffer) - 11); + buffer[0x0b] = dir_entry->attributes; +#if FAT_DATETIME_SUPPORT + write16(&buffer[0x16], dir_entry->modification_time); + write16(&buffer[0x18], dir_entry->modification_date); +#endif +#if FAT_FAT32_SUPPORT + write16(&buffer[0x14], (uint16_t) (dir_entry->cluster >> 16)); +#endif + write16(&buffer[0x1a], dir_entry->cluster); + write32(&buffer[0x1c], dir_entry->file_size); + + /* write to disk */ +#if FAT_LFN_SUPPORT + if(!device_write(offset + (uint16_t) lfn_entry_count * 32, buffer, sizeof(buffer))) +#else + if(!device_write(offset, buffer, sizeof(buffer))) +#endif + return 0; + +#if FAT_LFN_SUPPORT + /* calculate checksum of 8.3 name */ + uint8_t checksum = fat_calc_83_checksum(buffer); + + /* write lfn entries */ + for(uint8_t lfn_entry = lfn_entry_count; lfn_entry > 0; --lfn_entry) + { + memset(buffer, 0xff, sizeof(buffer)); + + /* set file name */ + const char* long_name_curr = name + (lfn_entry - 1) * 13; + uint8_t i = 1; + while(i < 0x1f) + { + buffer[i++] = *long_name_curr; + buffer[i++] = 0; + + switch(i) + { + case 0x0b: + i = 0x0e; + break; + case 0x1a: + i = 0x1c; + break; + } + + if(!*long_name_curr++) + break; + } + + /* set index of lfn entry */ + buffer[0x00] = lfn_entry; + if(lfn_entry == lfn_entry_count) + buffer[0x00] |= FAT_DIRENTRY_LFNLAST; + + /* mark as lfn entry */ + buffer[0x0b] = 0x0f; + + /* set 8.3 checksum */ + buffer[0x0d] = checksum; + + /* clear reserved bytes */ + buffer[0x0c] = 0; + buffer[0x1a] = 0; + buffer[0x1b] = 0; + + /* write entry */ + device_write(offset, buffer, sizeof(buffer)); + + offset += sizeof(buffer); + } +#endif + + return 1; +} +#endif + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_file + * Creates a file. + * + * Creates a file and obtains the directory entry of the + * new file. If the file to create already exists, the + * directory entry of the existing file will be returned + * within the dir_entry parameter. + * + * \note The file name is not checked for invalid characters. + * + * \note The generation of the short 8.3 file name is quite + * simple. The first eight characters are used for the filename. + * The extension, if any, is made up of the first three characters + * following the last dot within the long filename. If the + * filename (without the extension) is longer than eight characters, + * the lower byte of the cluster number replaces the last two + * characters to avoid name clashes. In any other case, it is your + * responsibility to avoid name clashes. + * + * \param[in] parent The handle of the directory in which to create the file. + * \param[in] file The name of the file to create. + * \param[out] dir_entry The directory entry to fill for the new (or existing) file. + * \returns 0 on failure, 1 on success, 2 if the file already existed. + * \see fat_delete_file + */ +uint8_t fat_create_file(struct fat_dir_struct* parent, const char* file, struct fat_dir_entry_struct* dir_entry) +{ + if(!parent || !file || !file[0] || !dir_entry) + return 0; + + /* check if the file already exists */ + while(1) + { + if(!fat_read_dir(parent, dir_entry)) + break; + + if(strcmp(file, dir_entry->long_name) == 0) + { + fat_reset_dir(parent); + return 2; + } + } + + struct fat_fs_struct* fs = parent->fs; + + /* prepare directory entry with values already known */ + memset(dir_entry, 0, sizeof(*dir_entry)); + strncpy(dir_entry->long_name, file, sizeof(dir_entry->long_name) - 1); + + /* find place where to store directory entry */ + if(!(dir_entry->entry_offset = fat_find_offset_for_dir_entry(fs, parent, dir_entry))) + return 0; + + /* write directory entry to disk */ + if(!fat_write_dir_entry(fs, dir_entry)) + return 0; + + return 1; +} +#endif + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_file + * Deletes a file or directory. + * + * If a directory is deleted without first deleting its + * subdirectories and files, disk space occupied by these + * files will get wasted as there is no chance to release + * it and mark it as free. + * + * \param[in] fs The filesystem on which to operate. + * \param[in] dir_entry The directory entry of the file to delete. + * \returns 0 on failure, 1 on success. + * \see fat_create_file + */ +uint8_t fat_delete_file(struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry) +{ + if(!fs || !dir_entry) + return 0; + + /* get offset of the file's directory entry */ + offset_t dir_entry_offset = dir_entry->entry_offset; + if(!dir_entry_offset) + return 0; + +#if FAT_LFN_SUPPORT + uint8_t buffer[12]; + while(1) + { + /* read directory entry */ + if(!fs->partition->device_read(dir_entry_offset, buffer, sizeof(buffer))) + return 0; + + /* mark the directory entry as deleted */ + buffer[0] = FAT_DIRENTRY_DELETED; + + /* write back entry */ + if(!fs->partition->device_write(dir_entry_offset, buffer, sizeof(buffer))) + return 0; + + /* check if we deleted the whole entry */ + if(buffer[11] != 0x0f) + break; + + dir_entry_offset += 32; + } +#else + /* mark the directory entry as deleted */ + uint8_t first_char = FAT_DIRENTRY_DELETED; + if(!fs->partition->device_write(dir_entry_offset, &first_char, 1)) + return 0; +#endif + + /* We deleted the directory entry. The next thing to do is + * marking all occupied clusters as free. + */ + return (dir_entry->cluster == 0 || fat_free_clusters(fs, dir_entry->cluster)); +} +#endif + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_file + * Moves or renames a file. + * + * Changes a file's name, optionally moving it into another + * directory as well. Before calling this function, the + * target file name must not exist. Moving a file to a + * different filesystem (i.e. \a parent_new doesn't lie on + * \a fs) is not supported. + * + * After successfully renaming (and moving) the file, the + * given directory entry is updated such that it points to + * the file's new location. + * + * \note The notes which apply to fat_create_file() also + * apply to this function. + * + * \param[in] fs The filesystem on which to operate. + * \param[in,out] dir_entry The directory entry of the file to move. + * \param[in] parent_new The handle of the new parent directory of the file. + * \param[in] file_new The file's new name. + * \returns 0 on failure, 1 on success. + * \see fat_create_file, fat_delete_file, fat_move_dir + */ +uint8_t fat_move_file(struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry, struct fat_dir_struct* parent_new, const char* file_new) +{ + if(!fs || !dir_entry || !parent_new || (file_new && !file_new[0])) + return 0; + if(fs != parent_new->fs) + return 0; + + /* use existing file name if none has been specified */ + if(!file_new) + file_new = dir_entry->long_name; + + /* create file with new file name */ + struct fat_dir_entry_struct dir_entry_new; + if(!fat_create_file(parent_new, file_new, &dir_entry_new)) + return 0; + + /* copy members of directory entry which do not change with rename */ + dir_entry_new.attributes = dir_entry->attributes; +#if FAT_DATETIME_SUPPORT + dir_entry_new.modification_time = dir_entry->modification_time; + dir_entry_new.modification_date = dir_entry->modification_date; +#endif + dir_entry_new.cluster = dir_entry->cluster; + dir_entry_new.file_size = dir_entry->file_size; + + /* make the new file name point to the old file's content */ + if(!fat_write_dir_entry(fs, &dir_entry_new)) + { + fat_delete_file(fs, &dir_entry_new); + return 0; + } + + /* delete the old file, but not its clusters, which have already been remapped above */ + dir_entry->cluster = 0; + if(!fat_delete_file(fs, dir_entry)) + return 0; + + *dir_entry = dir_entry_new; + return 1; +} +#endif + +#if DOXYGEN || FAT_WRITE_SUPPORT +/** + * \ingroup fat_dir + * Creates a directory. + * + * Creates a directory and obtains its directory entry. + * If the directory to create already exists, its + * directory entry will be returned within the dir_entry + * parameter. + * + * \note The notes which apply to fat_create_file() also + * apply to this function. + * + * \param[in] parent The handle of the parent directory of the new directory. + * \param[in] dir The name of the directory to create. + * \param[out] dir_entry The directory entry to fill for the new directory. + * \returns 0 on failure, 1 on success. + * \see fat_delete_dir + */ +uint8_t fat_create_dir(struct fat_dir_struct* parent, const char* dir, struct fat_dir_entry_struct* dir_entry) +{ + if(!parent || !dir || !dir[0] || !dir_entry) + return 0; + + /* check if the file or directory already exists */ + while(fat_read_dir(parent, dir_entry)) + { + if(strcmp(dir, dir_entry->long_name) == 0) + { + fat_reset_dir(parent); + return 0; + } + } + + struct fat_fs_struct* fs = parent->fs; + + /* allocate cluster which will hold directory entries */ + cluster_t dir_cluster = fat_append_clusters(fs, 0, 1); + if(!dir_cluster) + return 0; + + /* clear cluster to prevent bogus directory entries */ + fat_clear_cluster(fs, dir_cluster); + + memset(dir_entry, 0, sizeof(*dir_entry)); + dir_entry->attributes = FAT_ATTRIB_DIR; + + /* create "." directory self reference */ + dir_entry->entry_offset = fs->header.cluster_zero_offset + + (offset_t) (dir_cluster - 2) * fs->header.cluster_size; + dir_entry->long_name[0] = '.'; + dir_entry->cluster = dir_cluster; + if(!fat_write_dir_entry(fs, dir_entry)) + { + fat_free_clusters(fs, dir_cluster); + return 0; + } + + /* create ".." parent directory reference */ + dir_entry->entry_offset += 32; + dir_entry->long_name[1] = '.'; + dir_entry->cluster = parent->dir_entry.cluster; + if(!fat_write_dir_entry(fs, dir_entry)) + { + fat_free_clusters(fs, dir_cluster); + return 0; + } + + /* fill directory entry */ + strncpy(dir_entry->long_name, dir, sizeof(dir_entry->long_name) - 1); + dir_entry->cluster = dir_cluster; + + /* find place where to store directory entry */ + if(!(dir_entry->entry_offset = fat_find_offset_for_dir_entry(fs, parent, dir_entry))) + { + fat_free_clusters(fs, dir_cluster); + return 0; + } + + /* write directory to disk */ + if(!fat_write_dir_entry(fs, dir_entry)) + { + fat_free_clusters(fs, dir_cluster); + return 0; + } + + return 1; +} +#endif + +/** + * \ingroup fat_dir + * Deletes a directory. + * + * This is just a synonym for fat_delete_file(). + * If a directory is deleted without first deleting its + * subdirectories and files, disk space occupied by these + * files will get wasted as there is no chance to release + * it and mark it as free. + * + * \param[in] fs The filesystem on which to operate. + * \param[in] dir_entry The directory entry of the directory to delete. + * \returns 0 on failure, 1 on success. + * \see fat_create_dir + */ +#ifdef DOXYGEN +uint8_t fat_delete_dir(struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry); +#endif + +/** + * \ingroup fat_dir + * Moves or renames a directory. + * + * This is just a synonym for fat_move_file(). + * + * \param[in] fs The filesystem on which to operate. + * \param[in,out] dir_entry The directory entry of the directory to move. + * \param[in] parent_new The handle of the new parent directory. + * \param[in] dir_new The directory's new name. + * \returns 0 on failure, 1 on success. + * \see fat_create_dir, fat_delete_dir, fat_move_file + */ +#ifdef DOXYGEN +uint8_t fat_move_dir(struct fat_fs_struct* fs, struct fat_dir_entry_struct* dir_entry, struct fat_dir_struct* parent_new, const char* dir_new); +#endif + +#if DOXYGEN || FAT_DATETIME_SUPPORT +/** + * \ingroup fat_file + * Returns the modification date of a file. + * + * \param[in] dir_entry The directory entry of which to return the modification date. + * \param[out] year The year the file was last modified. + * \param[out] month The month the file was last modified. + * \param[out] day The day the file was last modified. + */ +void fat_get_file_modification_date(const struct fat_dir_entry_struct* dir_entry, uint16_t* year, uint8_t* month, uint8_t* day) +{ + if(!dir_entry) + return; + + *year = 1980 + ((dir_entry->modification_date >> 9) & 0x7f); + *month = (dir_entry->modification_date >> 5) & 0x0f; + *day = (dir_entry->modification_date >> 0) & 0x1f; +} +#endif + +#if DOXYGEN || FAT_DATETIME_SUPPORT +/** + * \ingroup fat_file + * Returns the modification time of a file. + * + * \param[in] dir_entry The directory entry of which to return the modification time. + * \param[out] hour The hour the file was last modified. + * \param[out] min The min the file was last modified. + * \param[out] sec The sec the file was last modified. + */ +void fat_get_file_modification_time(const struct fat_dir_entry_struct* dir_entry, uint8_t* hour, uint8_t* min, uint8_t* sec) +{ + if(!dir_entry) + return; + + *hour = (dir_entry->modification_time >> 11) & 0x1f; + *min = (dir_entry->modification_time >> 5) & 0x3f; + *sec = ((dir_entry->modification_time >> 0) & 0x1f) * 2; +} +#endif + +#if DOXYGEN || (FAT_WRITE_SUPPORT && FAT_DATETIME_SUPPORT) +/** + * \ingroup fat_file + * Sets the modification time of a date. + * + * \param[in] dir_entry The directory entry for which to set the modification date. + * \param[in] year The year the file was last modified. + * \param[in] month The month the file was last modified. + * \param[in] day The day the file was last modified. + */ +void fat_set_file_modification_date(struct fat_dir_entry_struct* dir_entry, uint16_t year, uint8_t month, uint8_t day) +{ + if(!dir_entry) + return; + + dir_entry->modification_date = + ((year - 1980) << 9) | + ((uint16_t) month << 5) | + ((uint16_t) day << 0); +} +#endif + +#if DOXYGEN || (FAT_WRITE_SUPPORT && FAT_DATETIME_SUPPORT) +/** + * \ingroup fat_file + * Sets the modification time of a file. + * + * \param[in] dir_entry The directory entry for which to set the modification time. + * \param[in] hour The year the file was last modified. + * \param[in] min The month the file was last modified. + * \param[in] sec The day the file was last modified. + */ +void fat_set_file_modification_time(struct fat_dir_entry_struct* dir_entry, uint8_t hour, uint8_t min, uint8_t sec) +{ + if(!dir_entry) + return; + + dir_entry->modification_time = + ((uint16_t) hour << 11) | + ((uint16_t) min << 5) | + ((uint16_t) sec >> 1) ; +} +#endif + +/** + * \ingroup fat_fs + * Returns the amount of total storage capacity of the filesystem in bytes. + * + * \param[in] fs The filesystem on which to operate. + * \returns 0 on failure, the filesystem size in bytes otherwise. + */ +offset_t fat_get_fs_size(const struct fat_fs_struct* fs) +{ + if(!fs) + return 0; + +#if FAT_FAT32_SUPPORT + if(fs->partition->type == PARTITION_TYPE_FAT32) + return (offset_t) (fs->header.fat_size / 4 - 2) * fs->header.cluster_size; + else +#endif + return (offset_t) (fs->header.fat_size / 2 - 2) * fs->header.cluster_size; +} + +/** + * \ingroup fat_fs + * Returns the amount of free storage capacity on the filesystem in bytes. + * + * \note As the FAT filesystem is cluster based, this function does not + * return continuous values but multiples of the cluster size. + * + * \param[in] fs The filesystem on which to operate. + * \returns 0 on failure, the free filesystem space in bytes otherwise. + */ +offset_t fat_get_fs_free(const struct fat_fs_struct* fs) +{ + if(!fs) + return 0; + + uint8_t fat[32]; + struct fat_usage_count_callback_arg count_arg; + count_arg.cluster_count = 0; + count_arg.buffer_size = sizeof(fat); + + offset_t fat_offset = fs->header.fat_offset; + uint32_t fat_size = fs->header.fat_size; + while(fat_size > 0) + { + uintptr_t length = UINTPTR_MAX - 1; + if(fat_size < length) + length = fat_size; + + if(!fs->partition->device_read_interval(fat_offset, + fat, + sizeof(fat), + length, +#if FAT_FAT32_SUPPORT + (fs->partition->type == PARTITION_TYPE_FAT16) ? + fat_get_fs_free_16_callback : + fat_get_fs_free_32_callback, +#else + fat_get_fs_free_16_callback, +#endif + &count_arg + ) + ) + return 0; + + fat_offset += length; + fat_size -= length; + } + + return (offset_t) count_arg.cluster_count * fs->header.cluster_size; +} + +/** + * \ingroup fat_fs + * Callback function used for counting free clusters in a FAT. + */ +uint8_t fat_get_fs_free_16_callback(uint8_t* buffer, offset_t offset, void* p) +{ + struct fat_usage_count_callback_arg* count_arg = (struct fat_usage_count_callback_arg*) p; + uintptr_t buffer_size = count_arg->buffer_size; + + for(uintptr_t i = 0; i < buffer_size; i += 2, buffer += 2) + { + uint16_t cluster = read16(buffer); + if(cluster == HTOL16(FAT16_CLUSTER_FREE)) + ++(count_arg->cluster_count); + } + + return 1; +} + +#if DOXYGEN || FAT_FAT32_SUPPORT +/** + * \ingroup fat_fs + * Callback function used for counting free clusters in a FAT32. + */ +uint8_t fat_get_fs_free_32_callback(uint8_t* buffer, offset_t offset, void* p) +{ + struct fat_usage_count_callback_arg* count_arg = (struct fat_usage_count_callback_arg*) p; + uintptr_t buffer_size = count_arg->buffer_size; + + for(uintptr_t i = 0; i < buffer_size; i += 4, buffer += 4) + { + uint32_t cluster = read32(buffer); + if(cluster == HTOL32(FAT32_CLUSTER_FREE)) + ++(count_arg->cluster_count); + } + + return 1; +} +#endif +