File System APIs
File System Functions
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int
fs_open
(ZFILE *zfp, const char *file_name) File open.
Opens an existing file or create a new one and associates a stream with it.
- Parameters
zfp
: Pointer to file objectfile_name
: The name of file to open
- Return Value
0
: Success-ERRNO
: errno code if error
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int
fs_close
(ZFILE *zfp) File close.
Flushes the associated stream and closes the file.
- Parameters
zfp
: Pointer to the file object
- Return Value
0
: Success-ERRNO
: errno code if error
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int
fs_unlink
(const char *path) File unlink.
Deletes the specified file or directory
- Parameters
path
: Path to the file or directory to delete
- Return Value
0
: Success-ERRNO
: errno code if error
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ssize_t
fs_read
(ZFILE *zfp, void *ptr, size_t size) File read.
Reads items of data of size bytes long.
- Return
- Number of bytes read. On success, it will be equal to number of items requested to be read. Returns less than number of bytes requested if there are not enough bytes available in file. Will return -ERRNO code on error.
- Parameters
zfp
: Pointer to the file objectptr
: Pointer to the data buffersize
: Number of bytes to be read
-
ssize_t
fs_write
(ZFILE *zfp, const void *ptr, size_t size) File write.
Writes items of data of size bytes long.
- Return
- Number of bytes written. On success, it will be equal to the number of bytes requested to be written. Any other value, indicates an error. Will return -ERRNO code on error. In the case where -ERRNO is returned, the file pointer will not be advanced because it couldn’t start the operation. In the case where it is able to write, but is not able to complete writing all of the requested number of bytes, then it is because the disk got full. In that case, it returns less number of bytes written than requested, but not a negative -ERRNO value as in regular error case.
- Parameters
zfp
: Pointer to the file objectptr
: Pointer to the data buffersize
: Number of bytes to be write
-
int
fs_seek
(ZFILE *zfp, off_t offset, int whence) File seek.
Moves the file position to a new location in the file. The offset is added to file position based on the ‘whence’ parameter.
- Parameters
zfp
: Pointer to the file objectoffset
: Relative location to move the file pointer towhence
: Relative location from where offset is to be calculated.- SEEK_SET = from beginning of file
- SEEK_CUR = from current position,
- SEEK_END = from end of file.
- Return Value
0
: Success-ERRNO
: errno code if error.
-
off_t
fs_tell
(ZFILE *zfp) Get current file position.
Retrieves the current position in the file.
- Parameters
zfp
: Pointer to the file object
- Return Value
position
: Current position in file Current revision does not validate the file object.
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int
fs_mkdir
(const char *path) Directory create.
Creates a new directory using specified path.
- Parameters
path
: Path to the directory to create
- Return Value
0
: Success-ERRNO
: errno code if error
-
int
fs_opendir
(ZDIR *zdp, const char *path) Directory open.
Opens an existing directory specified by the path.
- Parameters
zdp
: Pointer to the directory objectpath
: Path to the directory to open
- Return Value
0
: Success-ERRNO
: errno code if error
-
int
fs_readdir
(ZDIR *zdp, struct zfs_dirent *entry) Directory read entry.
Reads directory entries of a open directory
- Return
- In end-of-dir condition, this will return 0 and set entry->name[0] = 0
- Parameters
zdp
: Pointer to the directory objectentry
: Pointer to zfs_dirent structure to read the entry into
- Return Value
0
: Success-ERRNO
: errno code if error
-
int
fs_closedir
(ZDIR *zdp) Directory close.
Closes an open directory.
- Parameters
zdp
: Pointer to the directory object
- Return Value
0
: Success-ERRNO
: errno code if error
-
int
fs_stat
(const char *path, struct zfs_dirent *entry) File or directory status.
Checks the status of a file or directory specified by the path
- Parameters
path
: Path to the file or directoryentry
: Pointer to zfs_dirent structure to fill if file or directory exists.
- Return Value
0
: Success-ERRNO
: errno code if error
File System Data Structures
-
typedef
ZFILE
File object representing an open file.
-
typedef
ZDIR
Directory object representing an open directory.
-
struct
zfs_dirent
- #include <fs.h>
Structure to receive file or directory information.
Used in functions that reads the directory entries to get file or directory information.
- Parameters
dir_entry_type
: Whether file or directory- DIR_ENTRY_FILE
- DIR_ENTRY_DIR
name
: Name of directory or filesize
: Size of file. 0 if directory