minix/lib/libc/sys/getdents.2
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

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Groff

.\" $NetBSD: getdents.2,v 1.22 2010/06/04 05:42:24 jruoho Exp $
.\"
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.\" @(#)getdirentries.2 8.1 (Berkeley) 6/9/93
.\"
.Dd June 4, 2010
.Dt GETDENTS 2
.Os
.Sh NAME
.Nm getdents
.Nd "get directory entries in a filesystem independent format"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In dirent.h
.Ft int
.Fn getdents "int fd" "char *buf" "size_t nbytes"
.Sh DESCRIPTION
.Fn getdents
reads directory entries from the directory
referenced by the file descriptor
.Fa fd
into the buffer pointed to by
.Fa buf ,
in a filesystem independent format.
Up to
.Fa nbytes
of data will be transferred.
.Fa nbytes
must be greater than or equal to the
block size associated with the file,
see
.Xr stat 2 .
Some filesystems may not support
.Fn getdents
with buffers smaller than this size.
.Pp
The data in the buffer is a series of
.Em dirent
structures:
.Bd -literal -offset indent
struct dirent {
ino_t d_fileno; /* file number of entry */
uint16_t d_reclen; /* length of this record */
uint16_t d_namlen; /* length of d_name */
uint8_t d_type; /* file type, see below */
char d_name[MAXNAMELEN + 1];
};
.Ed
.Pp
The structure is described in
.Xr dirent 3 .
.Pp
Entries may be separated by extra space.
The
.Fa d_reclen
entry may be used as an offset from the start of a
.Fa dirent
structure to the next structure, if any.
.Pp
The actual number of bytes transferred is returned.
The current position pointer associated with
.Fa fd
is set to point to the next block of entries.
The pointer may not advance by the number of bytes returned by
.Fn getdents .
A value of zero is returned when
the end of the directory has been reached.
.Pp
The current position pointer may be set and retrieved by
.Xr lseek 2 .
The current position pointer should only be set to a value returned by
.Xr lseek 2 ,
or zero.
.Sh RETURN VALUES
If successful, the number of bytes actually transferred is returned.
Otherwise, \-1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn getdents
will fail if:
.Bl -tag -width "[EINVAL]"
.It Bq Er EBADF
.Fa fd
is not a valid file descriptor open for reading.
.It Bq Er EFAULT
Either
.Fa buf
points outside the allocated address space.
.It Bq Er EINVAL
A directory was being read on NFS, but it was modified on the server while
it was being read.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Sh SEE ALSO
.Xr lseek 2 ,
.Xr open 2 ,
.Xr dirent 3
.Sh HISTORY
The
.Fn getdents
function first appeared in
.Nx 1.3 .