readdir
read directory entry
1. readdir.2.man
Manpage of READDIR
READDIR
Section: Linux Programmer's Manual (2)Updated: 2007-06-01
Index Return to Main Contents
NAME
readdir - read directory entrySYNOPSIS
#include <linux/types.h> #include <linux/dirent.h> int readdir(unsigned int fd, struct dirent *dirp, unsigned int count);
DESCRIPTION
This is not the function you are interested in. Look at readdir(3) for the POSIX conforming C library interface. This page documents the bare kernel system call interface, which can change, and which is superseded by getdents(2).readdir() reads one dirent structure from the directory pointed at by fd into the memory area pointed to by dirp. The parameter count is ignored; at most one dirent structure is read.
The dirent structure is declared as follows:
struct dirent {
long d_ino; /* inode number */
off_t d_off; /* offset to this dirent */
unsigned short d_reclen; /* length of this d_name */
char d_name[NAME_MAX+1]; /* filename (null-terminated) */
}
d_ino is an inode number. d_off is the distance from the start of the directory to this dirent. d_reclen is the size of d_name, not counting the null terminator. d_name is a null-terminated filename.
RETURN VALUE
On success, 1 is returned. On end of directory, 0 is returned. On error, -1 is returned, and errno is set appropriately.ERRORS
- EBADF
- Invalid file descriptor fd.
- EFAULT
- Argument points outside the calling process's address space.
- EINVAL
- Result buffer is too small.
- ENOENT
- No such directory.
- ENOTDIR
- File descriptor does not refer to a directory.
CONFORMING TO
This system call is Linux-specific.NOTES
Glibc does not provide a wrapper for this system call; call it using syscall(2).SEE ALSO
getdents(2), readdir(3)COLOPHON
This page is part of release 2.78 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.
Index
This document was created by man2html using the manual pages.
Time: 23:22:17 GMT, July 09, 2008
2. readdir.3.man
Manpage of READDIR
READDIR
Section: Linux Programmer's Manual (3)Updated: 2007-07-30
Index Return to Main Contents
NAME
readdir - read a directorySYNOPSIS
#include <sys/types.h> #include <dirent.h> struct dirent *readdir(DIR *dir);
DESCRIPTION
The readdir() function returns a pointer to a dirent structure representing the next directory entry in the directory stream pointed to by dir. It returns NULL on reaching the end-of-file or if an error occurred.On Linux, the dirent structure is defined as follows:
struct dirent {
ino_t d_ino; /* inode number */
off_t d_off; /* offset to the next dirent */
unsigned short d_reclen; /* length of this record */
unsigned char d_type; /* type of file */
char d_name[256]; /* filename */
};
According to POSIX, the dirent structure contains a field char d_name[] of unspecified size, with at most NAME_MAX characters preceding the terminating null byte. POSIX.1-2001 also documents the field ino_t d_ino as an XSI extension. The other fields are unstandardized, and not present on all systems; see NOTES below for some further details.
The data returned by readdir() may be overwritten by subsequent calls to readdir() for the same directory stream.
RETURN VALUE
The readdir() function returns a pointer to a dirent structure, or NULL if an error occurs or end-of-file is reached. On error, errno is set appropriately.ERRORS
- EBADF
- Invalid directory stream descriptor dir.
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001NOTES
Only the fields d_name and d_ino are specified in POSIX.1-2001. The remaining fields are available on many, but not all systems. Under glibc, programs can check for the availability of the fields not defined in POSIX.1 by testing whether the macros _DIRENT_HAVE_D_NAMLEN, _DIRENT_HAVE_D_RECLEN, _DIRENT_HAVE_D_OFF, or _DIRENT_HAVE_D_TYPE are defined.Other than Linux, the d_type field is available mainly only on BSD systems. This field makes it possible to avoid the expense of calling stat(2) if further actions depend on the type of the file. If the _BSD_SOURCE feature test macro is defined, then glibc defines the following macro constants for the value returned in d_type:
- DT_UNKNOWN
- The file type is unknown.
- DT_REG
- This is a regular file.
- DT_DIR
- This is a directory.
- DT_FIFO
- This is a named pipe, or FIFO.
- DT_SOCK
- This is a Unix domain socket.
- DT_CHR
- This is a character device.
- DT_BLK
- This is a block device.
If the file type could not be determined, the value DT_UNKNOWN is returned in d_type.
SEE ALSO
read(2), closedir(3), dirfd(3), ftw(3), opendir(3), rewinddir(3), scandir(3), seekdir(3), telldir(3), feature_test_macros(7)COLOPHON
This page is part of release 2.78 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.
Index
This document was created by man2html using the manual pages.
Time: 23:22:17 GMT, July 09, 2008
