readdir(2)

1READDIR(2)                 Linux Programmer's Manual                READDIR(2)
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NAME

6       readdir - read directory entry
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SYNOPSIS

9       int readdir(unsigned int fd, struct old_linux_dirent *dirp,
10                   unsigned int count);
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12       Note: There is no glibc wrapper for this system call; see NOTES.
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DESCRIPTION

15       This is not the function you are interested in.  Look at readdir(3) for
16       the POSIX conforming C library interface.  This page documents the bare
17       kernel system call interface, which is superseded by getdents(2).
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19       readdir()  reads  one  old_linux_dirent  structure  from  the directory
20       referred to by the file descriptor fd into the  buffer  pointed  to  by
21       dirp.   The  argument  count  is  ignored; at most one old_linux_dirent
22       structure is read.
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24       The old_linux_dirent structure is declared (privately in  Linux  kernel
25       file fs/readdir.c) as follows:
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27           struct old_linux_dirent {
28               unsigned long d_ino;     /* inode number */
29               unsigned long d_offset;  /* offset to this old_linux_dirent */
30               unsigned short d_namlen; /* length of this d_name */
31               char  d_name[1];         /* filename (null-terminated) */
32           }
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34       d_ino  is  an inode number.  d_offset is the distance from the start of
35       the directory to  this  old_linux_dirent.   d_reclen  is  the  size  of
36       d_name,  not  counting  the  terminating null byte ('\0').  d_name is a
37       null-terminated filename.
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RETURN VALUE

40       On success, 1 is returned.  On end of directory,  0  is  returned.   On
41       error, -1 is returned, and errno is set appropriately.
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ERRORS

44       EBADF  Invalid file descriptor fd.
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46       EFAULT Argument points outside the calling process's address space.
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48       EINVAL Result buffer is too small.
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50       ENOENT No such directory.
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52       ENOTDIR
53              File descriptor does not refer to a directory.
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CONFORMING TO

56       This system call is Linux-specific.
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NOTES

59       Glibc  does  not  provide a wrapper for this system call; call it using
60       syscall(2).  You will need to  define  the  old_linux_dirent  structure
61       yourself.  However, probably you should use readdir(3) instead.
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63       This system call does not exist on x86-64.
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COLOPHON

69       This  page  is  part of release 5.02 of the Linux man-pages project.  A
70       description of the project, information about reporting bugs,  and  the
71       latest     version     of     this    page,    can    be    found    at
72       https://www.kernel.org/doc/man-pages/.
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76Linux                             2019-03-06                        READDIR(2)