Man pages for the openat(2), fexecve(2) and related syscalls.

Reviewed by:	ru

1 files changed, 60 insertions, 2 deletions

diff --git a/lib/libc/sys/readlink.2 b/lib/libc/sys/readlink.2
index 1c2593a..4b24052 100644
--- a/lib/libc/sys/readlink.2
+++ b/lib/libc/sys/readlink.2
@@ -28,11 +28,12 @@
 .\"     @(#)readlink.2	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd February 26, 2008
+.Dd April 10, 2008
 .Dt READLINK 2
 .Os
 .Sh NAME
-.Nm readlink
+.Nm readlink ,
+.Nm readlinkat
 .Nd read value of a symbolic link
 .Sh LIBRARY
 .Lb libc
@@ -40,6 +41,10 @@
 .In unistd.h
 .Ft ssize_t
 .Fn readlink "const char *restrict path" "char *restrict buf" "size_t bufsiz"
+.Ft ssize_t
+.Fo readlinkat
+.Fa "int fd" "const char *restrict path" "char *restrict buf" "size_t bufsize"
+.Fc
 .Sh DESCRIPTION
 The
 .Fn readlink
@@ -56,6 +61,27 @@ system call does not append a
 .Dv NUL
 character to
 .Fa buf .
+.Pp
+The
+.Fn readlinkat
+system call is equivalent to
+.Fn readlink
+except in the case where
+.Fa path
+specifies a relative path.
+In this case the symbolic link whose content is read relative to the
+directory associated with the file descriptor
+.Fa fd
+instead of the current working directory.
+If
+.Fn readlinkat
+is passed the special value
+.Dv AT_FDCWD
+in the
+.Fa fd
+parameter, the current working directory is used and the behavior is
+identical to a call to
+.Fn readlink .
 .Sh RETURN VALUES
 The call returns the count of characters placed in the buffer
 if it succeeds, or a \-1 if an error occurs, placing the error
@@ -88,13 +114,45 @@ The
 argument
 extends outside the process's allocated address space.
 .El
+.Pp
+In addition to the errors returned by the
+.Fn readlink ,
+the
+.Fn readlinkat
+may fail if:
+.Bl -tag -width Er
+.It Bq Er EBADF
+The
+.Fa path
+argument does not specify an absolute path and the
+.Fa fd
+argument is neither
+.Dv AT_FDCWD
+nor a valid file descriptor open for searching.
+.It Bq Er ENOTDIR
+The
+.Fa path
+argument is not an absolute path and
+.Fa fd
+is neither
+.Dv AT_FDCWD
+nor a file descriptor associated with a directory.
+.El
 .Sh SEE ALSO
 .Xr lstat 2 ,
 .Xr stat 2 ,
 .Xr symlink 2 ,
 .Xr symlink 7
+.Sh STANDARDS
+The
+.Fn readlinkat
+system call follows The Open Group Extended API Set 2 specification.
 .Sh HISTORY
 The
 .Fn readlink
 system call appeared in
 .Bx 4.2 .
+The
+.Fn readlinkat
+system call appeared in
+.Fx 8.0 .