Linux
2019-03-06
manpages-dev
Manual pages about using GNU/Linux for development
man-pages
Linux kernel and C library user-space interface documentation
NAME
readdir - read directory entry
SYNOPSIS
int readdir(unsigned int fd, struct old_linux_dirent *dirp, unsigned int count);
Note: There is no glibc wrapper for this system call; see NOTES.
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 This page documents the bare kernel system call interface, which is superseded by getdents(2).
readdir() reads one old_linux_dirent structure from the directory referred to by the file descriptor fd into the buffer pointed to by dirp. The argument count is ignored; at most one old_linux_dirent structure is read.
The old_linux_dirent structure is declared (privately in Linux kernel file fs/readdir.c) as follows:
struct old_linux_dirent {
unsigned long d_ino; /* inode number */
unsigned long d_offset; /* offset to this old_linux_dirent */
unsigned short d_namlen; /* length of this d_name */
char d_name[1]; /* filename (null-terminated) */ }
unsigned long d_ino; /* inode number */
unsigned long d_offset; /* offset to this old_linux_dirent */
unsigned short d_namlen; /* length of this d_name */
char d_name[1]; /* filename (null-terminated) */ }
d_ino is an inode number. d_offset is the distance from the start of the directory to this old_linux_dirent. d_reclen is the size of d_name, not counting the terminating null byte (\(aq\0\(aq). 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). You will need to define the old_linux_dirent structure yourself. However, probably you should use readdir(3) instead.
This system call does not exist on x86-64.
