The opendir() function opens a directory stream corresponding to the directory named by the dirname argument.

The fdopendir() function opens a directory stream for the directory file descriptor fildes. The directory file discriptor should not be used or closed following a successful function call, as this might cause undefined results from future operations on the directory stream obtained from the call. Use closedir(3C) to close a directory stream.

The directory stream is positioned at the first entry. If the type DIR is implemented using a file descriptor, applications will only be able to open up to a total of {OPEN_MAX} files and directories. A successful call to any of the exec functions will close any directory streams that are open in the calling process. See exec(2).

Upon successful completion, opendir() and fdopendir() return a pointer to an object of type DIR. Otherwise, a null pointer is returned and errno is set to indicate the error.

The opendir() function will fail if:

EACCES

Search permission is denied for the component of the path prefix of dirname or read permission is denied for dirname.

ELOOP

Too many symbolic links were encountered in resolving path.

ENAMETOOLONG

The length of the dirname argument exceeds {PATH_MAX}, or a path name component is longer than {NAME_MAX} while {_POSIX_NO_TRUNC} is in effect.

ENOENT

A component of dirname does not name an existing directory or dirname is an empty string.

ENOTDIR

A component of dirname is not a directory.

The fdopendir() function will fail if:

ENOTDIR

The file descriptor fildes does not reference a directory.

The opendir() function may fail if:

EMFILE

There are {OPEN_MAX} file descriptors currently open in the calling process.

ENAMETOOLONG

Pathname resolution of a symbolic link produced an intermediate result whose length exceeds PATH_MAX.

ENFILE

Too many files are currently open on the system.

The opendir() and fdopendir() functions should be used in conjunction with readdir(3C), closedir(3C) and rewinddir(3C) to examine the contents of the directory (see the EXAMPLES section in readdir(3C)). This method is recommended for portability.

See attributes(5) for descriptions of the following attributes:

lstat(2), symlink(2), closedir(3C), readdir(3C), rewinddir(3C), attributes(5)