getdents(2) - NetBSD Manual Pages

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GETDENTS(2)               NetBSD System Calls Manual               GETDENTS(2)


NAME

     getdents -- get directory entries in a filesystem independent format


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <dirent.h>

     int
     getdents(int fd, char *buf, size_t nbytes);


DESCRIPTION

     getdents() reads directory entries from the directory referenced by the
     file descriptor fd into the buffer pointed to by buf, in a filesystem
     independent format.  Up to nbytes of data will be transferred.  nbytes
     must be greater than or equal to the block size associated with the file,
     see stat(2).  Some filesystems may not support getdents() with buffers
     smaller than this size.

     The data in the buffer is a series of dirent structures each containing
     the following entries:

           ino_t           d_fileno;
           uint16_t        d_reclen;
           uint16_t        d_namlen;
           uint8_t d_type;
           char            d_name[MAXNAMLEN + 1]; /* see below */

     The d_fileno entry is a number which is unique for each distinct file in
     the filesystem.  Files that are linked by hard links (see link(2)) have
     the same d_fileno.  If d_fileno is zero, the entry refers to a deleted
     file.

     The d_reclen entry is the length, in bytes, of the directory record.

     The d_type is the type of file, where the following are possible types:
     DT_UNKNOWN, DT_FIFO, DT_CHR, DT_DIR, DT_BLK, DT_REG, DT_LNK, DT_SOCK, and
     DT_WHT.

     The d_namlen entry specifies the length of the file name excluding the
     null byte.  Thus the actual size of d_name may vary from 1 to MAXNAMLEN +
     1.

     The d_name entry contains a null terminated file name.

     Entries may be separated by extra space.  The d_reclen entry may be used
     as an offset from the start of a dirent structure to the next structure,
     if any.

     The actual number of bytes transferred is returned.  The current position
     pointer associated with fd is set to point to the next block of entries.
     The pointer may not advance by the number of bytes returned by
     getdents().  A value of zero is returned when the end of the directory
     has been reached.

     The current position pointer may be set and retrieved by lseek(2).  The
     current position pointer should only be set to a value returned by
     lseek(2), or zero.


RETURN VALUES

     If successful, the number of bytes actually transferred is returned.
     Otherwise, -1 is returned and the global variable errno is set to indi-
     cate the error.


ERRORS

     getdents() will fail if:

     [EBADF]            fd is not a valid file descriptor open for reading.

     [EFAULT]           Either buf points outside the allocated address space.

     [EIO]              An I/O error occurred while reading from or writing to
                        the file system.

     [EINVAL]           A directory was being read on NFS, but it was modified
                        on the server while it was being read.


SEE ALSO

     lseek(2), open(2), dirent(5)


HISTORY

     The getdents() function first appeared in NetBSD 1.3.

NetBSD 5.2                     September 6, 2005                    NetBSD 5.2