opendir

Opens a directory stream.

Syntax

   #include <sys/types.h>

   #include <dirent.h>

   DIR *opendir (const char *pathname);

Parameters

pathname: A pointer to a string containing a pathname of a directory to open. The pathname must be terminated by a null character.

Return Values

<>NULL: Success. A pointer to an object of type DIR is returned.
NULL: An error occurred. The directory is not opened, and errno is set to indicate the error condition.

Description

The opendir() function opens a directory stream associated with the directory specified by pathname and returns a pointer to the open directory stream to be used by subsequent calls to readdir(), rewinddir(), and closedir().

The directory stream is positioned at the first entry in the directory.

Implementation Considerations

Refer to the EFAULT, EIMPL, EMFILE, and ESYSERR error descriptions below.

The type DIR (defined in <dirent.h>) is implemented using a file descriptor. Applications can only open a total of {OPEN_MAX} files and directories.

The FD_CLOEXEC flag is not currently supported.

Errors

If an error occurs, errno is set to one of the following values:

`EACCES`	CAUSE	Either the calling process does not have search permission to a component of `pathname` or does not have read permission to the directory to be opened.
	ACTION	Make sure that the calling process has ACD traverse directory (TD) access for all components of the pathname and ACD read directory (RD) access to the directory to be opened.
`EFAULT`	CAUSE	The system detected a NULL or bad address in attempting to use the `pathname` parameter or the pathname was not terminated by a null character.
	ACTION	Make sure that the pointer is correctly initialized.
`EIMPL`	CAUSE	The pathname begins with two slash characters (//).
	ACTION	Do not begin pathnames with two slash characters (//).
`EMFILE`	CAUSE	The number of directory streams and files opened by the calling process would exceed `{OPEN_MAX}`.
	ACTION	Reduce the number of directories and files opened by the process.
`ENAMETOOLONG`	CAUSE	One of the following: The length of the pathname exceeds the `{PATH_MAX}` limit (defined in the file `<limits.h>`). A component of the pathname is longer than `{NAME_MAX}` (defined in `<limits.h>`), and `{_POSIX_NO_TRUNC}` is in effect for that directory.
	ACTION	Make sure that both the component's length and the full pathname length do not exceed the `{NAME_MAX}` or `{PATH_MAX}` limits.
`ENOENT`	CAUSE	The specified directory does not exist, or `pathname` points to an empty string.
	ACTION	Specify an existing directory name.
`ENOTDIR`	CAUSE	A component of the pathname is not a directory.
	ACTION	Specify a valid pathname.
`ESYSERR`	CAUSE	An operating system error has occurred that does not map directly to any of the above errors.
	ACTION	Examine the MPE/iX error stack for the type of system error.

opendir

Technical documentation

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