drnoodle / fat32

Read a FAT32 volume

Hugo Bonnome Arthur Passuello _____________________________________________________ FAT32

______________________________________ TEST RESULT

5/ 5 Parsing BPB 7/ 7 Debugfs /next_cluster/num checks 7/ 7 Basic start cluster checks 30/ 30 Test different readsizes 8/ 8 File reading checks 25/ 25 Test if ls/stat linux utils work 0/ 1 Test diff -r 7/ 7 Timestamps

_____________________________________ HEADER

dbugfs.h : Contains debugging functions.

util.h : Contains mmap and unmap.

vfat_cluster.h : Provides tools helping in the task of reading cluster from a fat32 volume.

vfat_directory.h : Provides tools helping in the task of extracting information from a directory.

vfat_boot.h : parse the FAT32 boot sector, verify integrity and store usefull information.

_____________________________________ VFAT_CLUSTER

_______________ PUBLIC FUNCTIONS

/**

• @param cluster_id A cluster identifier.
• @return The fat chain length
• @author Arthur Passuello */ int cluster_chain_size(uint32_t cluster_id);

/**

• @param buff An allocated pointer that will store
• the content of a cluster chain as an array of unsigned char
• @param cluster_id A cluster identifier
• @return The total number of clusters successfully read.
• @author Hugo Bonnome */ int load_cluster_chain(unsigned char * buff, uint32_t cluster_id);

/**

• @param cluster_id A cluster identifier.
• @return The Fat value entry for cluster cluster_id (i.e the next cluster id)
• @author Hugo Bonnome */ int vfat_next_cluster(uint32_t cluster_id);

_______________ PRIVATE FUNCTIONS

/**

• @param cluster_id A cluster identifier.
• @return A boolean value indicating that
• the cluster identifier given as parameter is the last element
• of the fat chain.
• @author Hugo Bonnome */ static int is_end_of_cluster_chain(uint32_t cluster_id);

/**

• @param buff An allocated pointer that will store
• the content of a cluster as an array of unsigned char
• @param cluster_id A cluster identifier
• @return boolean value answering : has error during the operation ?
• @author Arthur Passuello */ static int load_cluster(unsigned char * buff, uint32_t cluster_id);

_____________________________________ VFAT_DIRECTORY

_______________ PUBLIC FUNCTIONS

/**

• @param first_cluster The cluster identifier related to the first
• cluster of a directory.
• @param callback A function (void*, const char*,const struct stat , void) => int
• @param callbackdata A pointer to something
• @return A boolean answering : is error during the process ?
• @author Hugo Bonnome */ int vfat_readdir(uint32_t first_cluster, fuse_fill_dir_t callback, void *callbackdata);

/**

• @param data A pointer to a vfat_search_data(request).
• @param name The file name of a file tested where we're currently looking.
• @param st A pointer to a struct stat that contains informations about the file tested
• @param offs The offset of the file tested in the current directory (in bytes)
• @return A boolean answering : is the request equals to the tested file ?
• @author Arthur Passuello */ int vfat_search_entry(void *data, const char *name, const struct stat *st, off_t offs);

/**

• @param path The path to a requested file
• @param st A pointer to a stat that will contains informations of the request.
• @return A boolean answering : is st correctly loaded (~search succeed) ?
• @author Hugo Bonnome */ int vfat_resolve(const char *path, struct stat *st);

_______________ PRIVATE FUNCTIONS

/**

• @param entry_pt A pointer to data.
• @return A boolean value answering : is a long direntry ?
• @author Arthur Passuello */ static int is_long_dir_entry(unsigned char * entry_pt);

/**

• @param c A pointer to a character
• @return A boolean answering :
• is the char conform to the fat32 filename ?
• @author Arthur Passuello */ static int is_a_conform_filename_char(unsigned char * c);

/**

• @param direntry A pointer to a fat32_direntry.
• @return A boolean value answering : is a valid direntry ?
• @author Hugo Bonnome */ static int is_a_valid_dir_entry_short(struct fat32_direntry * direntry);

/**

• @param direntry A pointer to a direntry_long.
• @return A boolean value answering : is a valid direntry_long ?
• @author Hugo Bonnome */ static int is_a_valid_dir_entry_long( struct fat32_direntry_long * direntry, unsigned char expected_checksum);

/**

• @brief compute The checksum of the filename.
• @param pFcbName The name to be hashed
• @return The checksum of the string
• @author Microsoft */ static unsigned char checksum(unsigned char *pFcbName);

/**

• @param short_dir_pt A pointer to the short direntry representing the long direntry.
• @param parsed_name An allocated buff of char that will contain the name of the long direntry.
• @return A boolean answering : is an error during parsing process ?
• @brief load the long name of the short direntry given as parameter.
• @author Hugo Bonnome */ static int parse_long_name( unsigned char const * const short_dir_pt, char * const parsed_name);

/**

• @param name a pointer to the name
• @brief remove useless space at the end of the string
• @author Arthur Passuello */ static void normalize_name(char * name);

/**

• @param date a fat32 date
• @param time a fat32 time
• @return a date converted in unix style
• @author Hugo Bonnome */ static uint32_t parse_date(uint16_t date, uint16_t time);

_____________________________________ VFAT_BOOT

_______________ PUBLIC FUNCTIONS /**

• @brief Load the vfat_info declared above
• using the fat_boot_header structure and
• the first 512 bytes from the .fat file.
• @param dev The volume to mount
• @author Hugo Bonnome, Arthur Passuello */ void vfat_init(const char *dev);