September 6, 2005 GETDENTS 2

### NAME

getdents - get directory entries in a filesystem independent format

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```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 indicate 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 NetBSD1.3.