POSIX

POSIX-standard APIs for managing the filesystem. More...

Files
file	libgen.h
	Definitions for pattern matching functions.
file	dirent.h
	Directory entry functionality.
file	uio.h
	Header for vector I/O.

Data Structures
struct	dirent
	POSIX directory entry structure. More...
struct	DIR
	Type representing a directory stream. More...
struct	iovec_t
	I/O vector structure. More...

Macros
#define	UIO_MAXIOV   IOV_MAX
	Old alias for the maximum length of an iovec.

Functions
char *	basename (char *path)
	Get the last component of a pathname.
char *	dirname (char *path)
	Get the parent directory of a file pathname.
DIR *	opendir (const char *name)
	Open a directory based on the specified name.
int	closedir (DIR *dir)
	Closes a directory that was previously opened.
struct dirent *	readdir (DIR *dir)
	Read an entry from a directory stream.
int	dirfd (DIR *dirp)
	Retrieve the file descriptor of an opened directory stream.
void	rewinddir (DIR *dir)
	Rewind a directory stream to the start of the directory.
int	scandir (const char *__RESTRICT dir, struct dirent ***__RESTRICT namelist, int(*filter)(const struct dirent *), int(*compar)(const struct dirent **, const struct dirent **))
	Scan, filter, and sort files within a directory.
int	alphasort (const struct dirent **a, const struct dirent **b)
	Comparison function for sorting directory entries alphabetically.
void	seekdir (DIR *dir, off_t offset)
	Not implemented.
off_t	telldir (DIR *dir)
	Not implemented.

Directory File Types
POSIX file types for dirent::d_name Remarks These directory entry types are not part of the POSIX specifican per-se, but are used by BSD and glibc. Todo: Ensure each VFS driver maps its directory types accordingly
#define	DT_UNKNOWN   0
	Unknown.
#define	DT_FIFO   1
	Named Pipe or FIFO.
#define	DT_CHR   2
	Character Device.
#define	DT_DIR   4
	Directory.
#define	DT_BLK   6
	Block Device.
#define	DT_REG   8
	Regular File.
#define	DT_LNK   10
	Symbolic Link.
#define	DT_SOCK   12
	Local-Domain Socket.
#define	DT_WHT   14
	Whiteout (ignored)

Detailed Description

POSIX-standard APIs for managing the filesystem.

Macro Definition Documentation

DT_BLK

#define DT_BLK   6

Block Device.

DT_CHR

#define DT_CHR   2

Character Device.

DT_DIR

#define DT_DIR   4

Directory.

DT_FIFO

#define DT_FIFO   1

Named Pipe or FIFO.

DT_LNK

#define DT_LNK   10

Symbolic Link.

DT_REG

#define DT_REG   8

Regular File.

DT_SOCK

#define DT_SOCK   12

Local-Domain Socket.

DT_UNKNOWN

#define DT_UNKNOWN   0

Unknown.

DT_WHT

#define DT_WHT   14

Whiteout (ignored)

UIO_MAXIOV

#define UIO_MAXIOV   IOV_MAX

Old alias for the maximum length of an iovec.

Function Documentation

alphasort()

int alphasort	(	const struct dirent **	a,
		const struct dirent **	b
	)

Comparison function for sorting directory entries alphabetically.

Sorts two directory entries, a and b in alphabetical order.

Note

This function can be used as the comparison callback passed to scandir(), to sort the returned list of entries in alphabetical order.

Parameters

a	The first directory entry to sort
b	The second directory entry to sort

Return values

Returns

an integer value greater than, equal to, or less than zero, depending on whether the name of the directory entry pointed to by a is lexically greater than, equal to, or less than the directory entry pointed to by b.

See also

scandir()

basename()

char * basename

(

char *

path

)

Get the last component of a pathname.

This function retrieves the basename from a given path. The basename of a path is the non-directory component thereof, minus any trailing '/' characters. This function does not attempt to perform any sort of path resolution.

Note

This function may modify its input and the returned value may be a pointer to part of its input.

Parameters

path	The path to extract the basename from.

Returns

A pointer to the basename of the given path.

closedir()

int closedir

(

DIR *

dir

)

Closes a directory that was previously opened.

This function is used to close a directory stream that was previously opened with the opendir() function. You must do this to clean up any resources associated with the directory stream.

Parameters

dir	The directory stream to close.

Returns

0 on success. -1 on error, setting errno as appropriate.

dirfd()

int dirfd

(

DIR *

dirp

)

Retrieve the file descriptor of an opened directory stream.

This function retrieves the file descriptor of a directory stream that was previously opened with opendir().

Warning

Do not close() the returned file descriptor. It will be closed when closedir() is called on the directory stream.

Parameters

dirp	The directory stream to retrieve the descriptor of.

Returns

The file descriptor from the directory stream on success or -1 on failure (sets errno as appropriate).

dirname()

char * dirname

(

char *

path

)

Get the parent directory of a file pathname.

This function retrieves the name of the parent directory of the file pathname specified. This function does not attempt to perform any sort of path resolution to check for the existence of the specified directory or to resolve any symbolic links.

Note

This function may modify its input and the returned value may be a pointer to part of its input.

Parameters

path	The path to extract the parent directory from.

Returns

A pointer to the parent directory of the given path.

opendir()

DIR * opendir

(

const char *

name

)

Open a directory based on the specified name.

The directory specified is opened if it exists. A directory stream object is returned for accessing the entries of the directory.

Note

As with other functions for opening files on the VFS, relative paths are permitted for the name parameter of this function.

Parameters

name	The name of the directory to open.

Returns

A directory stream object to be used with readdir() on success, NULL on failure. Sets errno as appropriate.

See also

closedir

readdir

readdir()

struct dirent * readdir

(

DIR *

dir

)

Read an entry from a directory stream.

This function reads the next entry from the directory stream provided, returning the directory entry associated with the next object in the directory.

Warning

Do not free the returned dirent!

Parameters

dir	The directory stream to read from.

Returns

A pointer to the next directory entry in the directory or NULL if there are no other entries in the directory. If an error is incurred, NULL will be returned and errno set to indicate the error.

rewinddir()

void rewinddir

(

DIR *

dir

)

Rewind a directory stream to the start of the directory.

This function rewinds the directory stream so that the next call to the readdir() function will return the first entry in the directory.

Warning

Some filesystems do not support this call. Notably, none of the dcload filesystems support it. Error values will be returned in errno (so set errno to 0, then check after calling the function to see if there was a problem anywhere).

Parameters

dir	The directory stream to rewind.

scandir()

int scandir	(	const char *__RESTRICT	dir,
		struct dirent ***__RESTRICT	namelist,
		int(*)(const struct dirent *)	filter,
		int(*)(const struct dirent **, const struct dirent **)	compar
	)

Scan, filter, and sort files within a directory.

This function scans through all files within the directory located at the path given by dir, calling filter on each entry. Entries for which filter returns nonzero are stored within namelist and are sorted using qsort() with the comparison function, compar. The resulting directory entries are accumulated and stored witin namelist.

Note

filter and compar may be NULL, if you do not wish to filter or sort the files.

Warning

The entries within namelist are each independently heap-allocated, then the list itself heap allocated, so each entry must be freed within the list followed by the list itself.

Parameters

dir	The path to the directory to scan
namelist	A pointer through which the list of entries will be returned.
filter	The callback used to filter each directory entry (returning 1 for inclusion, 0 for exclusion).
compar	The callback passed to qsort() to sort namelist by

Return values

>=0	On success, the number of directory entries within namelist is returned
-1	On failure, -1 is returned and errno is set

See also

alphasort

seekdir()

void seekdir	(	DIR *	dir,
		off_t	offset
	)

Not implemented.

telldir()

off_t telldir

(

DIR *

dir

)

Not implemented.