Mac OS X Manual Page For getdirentries(2)

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GETDIRENTRIES(2) BSD System Calls Manual GETDIRENTRIES(2)

NAME
getdirentries -- get directory entries in a filesystem independent format

SYNOPSIS
#include <sys/types.h>
#include <sys/dirent.h>

int
getdirentries(int fd, char *buf, int nbytes, long *basep);

DESCRIPTION
Getdirentries() 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 getdirentries() with
buffers smaller than this size.

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

u_int32_t d_fileno; /* file number of entry */
u_int16_t d_reclen; /* length of this record */
u_int8_t d_type; /* file type, see below */
u_int8_t d_namlen; /* length of string in d_name */
char d_name[MAXNAMELEN + 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. Users of getdirentries() should skip entries with
d_fileno = 0, as such entries represent files which have been deleted but
not yet removed from the directory entry. The d_reclen entry is the
length, in bytes, of the directory record. The d_name entry contains a
null terminated file name. 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 MAXNAMELEN + 1. d_type is a integer representing the
type of the directory entry. The following types are defined in
<sys/dirent.h>:

#define DT_UNKNOWN 0
#define DT_FIFO 1
#define DT_CHR 2
#define DT_DIR 4
#define DT_BLK 6
#define DT_REG 8
#define DT_LNK 10
#define DT_SOCK 12
#define DT_WHT 14

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
getdirentries(). A value of zero is returned when the end of the direc-tory directory
tory has been reached.

Getdirentries() writes the position of the block read into the location
pointed to by basep. Alternatively, 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), a value returned in the location
pointed to by basep, 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 indicate
cate the error.

ERRORS
Getdirentries() will fail if:

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

[EFAULT] Either buf or basep point outside the allocated
address space.

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