GETDIRENTRIES(2) BSD System Calls Manual GETDIRENTRIES(2)NAME
getdirentries, getdents — get directory entries in a filesystem indepen‐
dent format
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/types.h>
#include <dirent.h>
int
getdirentries(int fd, char *buf, int nbytes, long *basep);
int
getdents(int fd, char *buf, int nbytes);
size_t
_DIRENT_DIRSIZ(struct dirent *dp);
struct dirent *
_DIRENT_NEXT(struct dirent *dp);
DESCRIPTION
The getdirentries() and getdents() functions read 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. The nbytes argument must be greater than or
equal to the block size associated with the file, see stat(2). Some
filesystems may not support these functions 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;
u_int8_t d_type;
u_int8_t d_namlen;
char d_name[...]; /* 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. The d_type entry is the type of the file pointed to
by the directory record. The file type values are defined in
<sys/dirent.h>. 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.
Entries may be separated by extra space. To get the total size of a
dirent structure, use the _DIRENT_DIRSIZ macro, or use _DIRENT_NEXT to
get a pointer to the following dirent structure.
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() or getdents(). A value of zero is returned when the end
of the directory has been reached.
The getdirentries() function 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 (getdirentries() only) 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.
ERRORSGetdirentries() 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.
[EINVAL] The file referenced by fd is not a directory, or
nbytes is too small for returning a directory entry or
block of entries, or the current position pointer is
invalid.
[EIO] An I/O error occurred while reading from or writing to
the file system.
SEE ALSOlseek(2), open(2)HISTORY
The getdirentries() function first appeared in 4.4BSD. The getdents()
function first appeared in FreeBSD 3.0.
BUGS
Unfortunately, *basep is only 32 bits wide on 32 bit platforms and may
not be wide enough to accommodate the directory position cookie. Modern
users should use lseek(2). to retrieve and set the seek position within
the directory. The seek offset is 64 bits wide on all platforms.
BSD July 31, 2006 BSD
