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dirent

Data structure for a directory entry

Synopsis:

#include <dirent.h>

struct dirent {
#if _FILE_OFFSET_BITS - 0 == 64
    ino_t           d_ino;     /* File serial number. */
    off_t           d_offset;
#elif !defined(_FILE_OFFSET_BITS) || _FILE_OFFSET_BITS == 32
#if defined(__LITTLEENDIAN__)
    ino_t           d_ino;     /* File serial number. */
    ino_t           d_ino_hi;
    off_t           d_offset;
    off_t           d_offset_hi;
#elif defined(__BIGENDIAN__)
    ino_t           d_ino_hi;
    ino_t           d_ino;     /* File serial number. */
    off_t           d_offset_hi;
    off_t           d_offset;
#else
 #error endian not configured for system
#endif
#else
 #error _FILE_OFFSET_BITS value is unsupported
#endif
    _Int16t             d_reclen;
    _Int16t             d_namelen;
    char                d_name[1];
};

Description:

The dirent structure describes an entry in a directory. The members include:

d_ino

A mountpoint-unique file serial number. This serial number is often used in various disk-checking utilities for such operations as determining infinite-loop directory links. (Note that the inode value cannot be zero, which would indicate that the inode represents an unused entry.)

d_offset

In some filesystems, this member identifies the directory entry itself; in others, it's the offset of the next directory entry. For a disk-based filesystem, this value might be the actual offset into the on-disk directory structure.

d_reclen

The size of this directory entry and any other associated information (such as an optional struct stat structure appended to the struct dirent entry).

d_namelen

The size of the d_name member. Since the size is calculated using strlen(), the \0 string terminator, which must be present, isn't counted.

d_name

The actual name of that directory entry.

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The struct dirent structure doesn't include space for the pathname. If you create an instance of this structure, you must provide space for the name: struct dirent *entry; entry = malloc( offsetof(struct dirent, d_name) + NAME_MAX + 1 ); or: struct { struct dirent ent; char namebuf[NAME_MAX + 1 + offsetof(struct dirent, d_name) - sizeof( struct dirent)]; } entry

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Classification:

POSIX 1003.1

See also:

readdir(), readdir_r(), scandir()