This module implements FAT16/FAT32 read and write access. More...

Data Structures
struct	fat_dir_entry_struct
	Describes a directory entry. More...
Modules
	FAT configuration
	Preprocessor defines to configure the FAT implementation.
	FAT access
	Basic functions for handling a FAT filesystem.
	FAT file functions
	Functions for managing files.
	FAT directory functions
	Functions for managing directories.
Files
file	fat.c
	FAT implementation (license: GPLv2 or LGPLv2.1)
file	fat.h
	FAT header (license: GPLv2 or LGPLv2.1)
file	fat_config.h
	FAT configuration (license: GPLv2 or LGPLv2.1)
Functions
struct fat_fs_struct *	fat_open (struct partition_struct *partition)
	Opens a FAT filesystem.
void	fat_close (struct fat_fs_struct *fs)
	Closes a FAT filesystem.
struct fat_file_struct *	fat_open_file (struct fat_fs_struct fs, const struct fat_dir_entry_struct dir_entry)
	Opens a file on a FAT filesystem.
void	fat_close_file (struct fat_file_struct *fd)
	Closes a file.
intptr_t	fat_read_file (struct fat_file_struct fd, uint8_t buffer, uintptr_t buffer_len)
	Reads data from a file.
intptr_t	fat_write_file (struct fat_file_struct fd, const uint8_t buffer, uintptr_t buffer_len)
	Writes data to a file.
uint8_t	fat_seek_file (struct fat_file_struct fd, int32_t offset, uint8_t whence)
	Repositions the read/write file offset.
uint8_t	fat_resize_file (struct fat_file_struct *fd, uint32_t size)
	Resizes a file to have a specific size.
struct fat_dir_struct *	fat_open_dir (struct fat_fs_struct fs, const struct fat_dir_entry_struct dir_entry)
	Opens a directory.
void	fat_close_dir (struct fat_dir_struct *dd)
	Closes a directory descriptor.
uint8_t	fat_read_dir (struct fat_dir_struct dd, struct fat_dir_entry_struct dir_entry)
	Reads the next directory entry contained within a parent directory.
uint8_t	fat_reset_dir (struct fat_dir_struct *dd)
	Resets a directory handle.
uint8_t	fat_create_file (struct fat_dir_struct parent, const char file, struct fat_dir_entry_struct *dir_entry)
	Creates a file.
uint8_t	fat_delete_file (struct fat_fs_struct fs, struct fat_dir_entry_struct dir_entry)
	Deletes a file or directory.
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)
	Moves or renames a file.
uint8_t	fat_create_dir (struct fat_dir_struct parent, const char dir, struct fat_dir_entry_struct *dir_entry)
	Creates a directory.
void	fat_get_file_modification_date (const struct fat_dir_entry_struct dir_entry, uint16_t year, uint8_t month, uint8_t day)
	Returns the modification date of a file.
void	fat_get_file_modification_time (const struct fat_dir_entry_struct dir_entry, uint8_t hour, uint8_t min, uint8_t sec)
	Returns the modification time of a file.
uint8_t	fat_get_dir_entry_of_path (struct fat_fs_struct fs, const char path, struct fat_dir_entry_struct *dir_entry)
	Retrieves the directory entry of a path.
offset_t	fat_get_fs_size (const struct fat_fs_struct *fs)
	Returns the amount of total storage capacity of the filesystem in bytes.
offset_t	fat_get_fs_free (const struct fat_fs_struct *fs)
	Returns the amount of free storage capacity on the filesystem in bytes.

Detailed Description

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.

Function Documentation

void fat_close ( struct fat_fs_struct * fs )

Closes a FAT filesystem.

When this function returns, the given filesystem descriptor will be invalid.

Parameters:

[in] fs The filesystem to close.

See also:: fat_open

void fat_close_dir ( struct fat_dir_struct * dd )

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.

Parameters:

[in] dd The directory descriptor to close.

See also:: fat_open_dir

void fat_close_file ( struct fat_file_struct * fd )

Closes a file.

Parameters:

[in] fd The file handle of the file to close.

See also:: fat_open_file

uint8_t fat_create_dir	(	struct fat_dir_struct *	parent,
		const char *	dir,
		struct fat_dir_entry_struct *	dir_entry
	)

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.

Parameters:

[in]	parent	The handle of the parent directory of the new directory.
[in]	dir	The name of the directory to create.
[out]	dir_entry	The directory entry to fill for the new directory.

Returns:: 0 on failure, 1 on success.

See also:: fat_delete_dir

uint8_t fat_create_file	(	struct fat_dir_struct *	parent,
		const char *	file,
		struct fat_dir_entry_struct *	dir_entry
	)

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.; 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.

Parameters:

[in]	parent	The handle of the directory in which to create the file.
[in]	file	The name of the file to create.
[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 also:: fat_delete_file

uint8_t fat_delete_file	(	struct fat_fs_struct *	fs,
		struct fat_dir_entry_struct *	dir_entry
	)

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.

Parameters:

[in]	fs	The filesystem on which to operate.
[in]	dir_entry	The directory entry of the file to delete.

Returns:: 0 on failure, 1 on success.

See also:: fat_create_file

uint8_t fat_get_dir_entry_of_path	(	struct fat_fs_struct *	fs,
		const char *	path,
		struct fat_dir_entry_struct *	dir_entry
	)

Retrieves the directory entry of a path.

The given path may both describe a file or a directory.

Parameters:

[in]	fs	The FAT filesystem on which to search.
[in]	path	The path of which to read the directory entry.
[out]	dir_entry	The directory entry to fill.

Returns:: 0 on failure, 1 on success.

See also:: fat_read_dir

void fat_get_file_modification_date	(	const struct fat_dir_entry_struct *	dir_entry,
		uint16_t *	year,
		uint8_t *	month,
		uint8_t *	day
	)

Returns the modification date of a file.

Parameters:

[in]	dir_entry	The directory entry of which to return the modification date.
[out]	year	The year the file was last modified.
[out]	month	The month the file was last modified.
[out]	day	The day 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
	)

Returns the modification time of a file.

Parameters:

[in]	dir_entry	The directory entry of which to return the modification time.
[out]	hour	The hour the file was last modified.
[out]	min	The min the file was last modified.
[out]	sec	The sec the file was last modified.

offset_t fat_get_fs_free ( const struct fat_fs_struct * 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.

Parameters:

[in] fs The filesystem on which to operate.

Returns:: 0 on failure, the free filesystem space in bytes otherwise.

offset_t fat_get_fs_size ( const struct fat_fs_struct * fs )

Returns the amount of total storage capacity of the filesystem in bytes.

Parameters:

[in] fs The filesystem on which to operate.

Returns:: 0 on failure, the filesystem size in bytes otherwise.

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
	)

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. parent_new doesn't lie on 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.

Parameters:

[in]	fs	The filesystem on which to operate.
[in,out]	dir_entry	The directory entry of the file to move.
[in]	parent_new	The handle of the new parent directory of the file.
[in]	file_new	The file's new name.

Returns:: 0 on failure, 1 on success.

See also:: fat_create_file, fat_delete_file, fat_move_dir

struct fat_fs_struct* fat_open ( struct partition_struct * partition ) [read]

Opens a FAT filesystem.

Parameters:

[in] partition Discriptor of partition on which the filesystem resides.

Returns:: 0 on error, a FAT filesystem descriptor on success.

See also:: fat_close

struct fat_dir_struct* fat_open_dir	(	struct fat_fs_struct *	fs,
		const struct fat_dir_entry_struct *	dir_entry
	)		`[read]`

Opens a directory.

Parameters:

[in]	fs	The filesystem on which the directory to open resides.
[in]	dir_entry	The directory entry which stands for the directory to open.

Returns:: An opaque directory descriptor on success, 0 on failure.

See also:: fat_close_dir

struct fat_file_struct* fat_open_file	(	struct fat_fs_struct *	fs,
		const struct fat_dir_entry_struct *	dir_entry
	)		`[read]`

Opens a file on a FAT filesystem.

Parameters:

[in]	fs	The filesystem on which the file to open lies.
[in]	dir_entry	The directory entry of the file to open.

Returns:: The file handle, or 0 on failure.

See also:: fat_close_file

uint8_t fat_read_dir	(	struct fat_dir_struct *	dd,
		struct fat_dir_entry_struct *	dir_entry
	)

Reads the next directory entry contained within a parent directory.

Parameters:

[in]	dd	The descriptor of the parent directory from which to read the entry.
[out]	dir_entry	Pointer to a buffer into which to write the directory entry information.

Returns:: 0 on failure, 1 on success.

See also:: fat_reset_dir

intptr_t fat_read_file	(	struct fat_file_struct *	fd,
		uint8_t *	buffer,
		uintptr_t	buffer_len
	)

Reads data from a file.

The data requested is read from the current file location.

Parameters:

[in]	fd	The file handle of the file from which to read.
[out]	buffer	The buffer into which to write.
[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 also:: fat_write_file

uint8_t fat_reset_dir ( struct fat_dir_struct * dd )

Resets a directory handle.

Resets the directory handle such that reading restarts with the first directory entry.

Parameters:

[in] dd The directory handle to reset.

Returns:: 0 on failure, 1 on success.

See also:: fat_read_dir

uint8_t fat_resize_file	(	struct fat_file_struct *	fd,
		uint32_t	size
	)

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.

Parameters:

[in]	fd	The file decriptor of the file which to resize.
[in]	size	The new size of the file.

Returns:: 0 on failure, 1 on success.

uint8_t fat_seek_file	(	struct fat_file_struct *	fd,
		int32_t *	offset,
		uint8_t	whence
	)

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 whence parameter:

FAT_SEEK_SET: *offset is relative to the beginning of the file.
FAT_SEEK_CUR: *offset is relative to the current file position.
FAT_SEEK_END: *offset is relative to the end of the file.

The resulting absolute offset is written to the location the offset parameter points to.

Calling this function can also be used to retrieve the current file position:

   int32_t file_pos = 0;
   if(!fat_seek_file(fd, &file_pos, FAT_SEEK_CUR))
   {
       // error
   }
   // file_pos now contains the absolute file position

Parameters:

[in]	fd	The file decriptor of the file on which to seek.
[in,out]	offset	A pointer to the new offset, as affected by the `whence` parameter. The function writes the new absolute offset to this location before it returns.
[in]	whence	Affects the way `offset` is interpreted, see above.

Returns:: 0 on failure, 1 on success.

intptr_t fat_write_file	(	struct fat_file_struct *	fd,
		const uint8_t *	buffer,
		uintptr_t	buffer_len
	)

Writes data to a file.

The data is written to the current file location.

Parameters:

[in]	fd	The file handle of the file to which to write.
[in]	buffer	The buffer from which to read the data to be written.
[in]	buffer_len	The amount of data to write.

Returns:: The number of bytes written (0 or something less than buffer_len on disk full) or -1 on failure.

See also:: fat_read_file

Data Structures

Modules

Files

Functions

Detailed Description

Function Documentation