xnu-2782.40.9.tar.gz

[apple/xnu.git] / bsd / man / man2 / access.2

diff --git a/bsd/man/man2/access.2 b/bsd/man/man2/access.2
index 0d168d3c81179a162f64aaab7a7fea8ad45f1c32..2c89f7a1153e858ef5ddea175c6d51782f5130d5 100644 (file)
--- a/bsd/man/man2/access.2
+++ b/bsd/man/man2/access.2
@@ -37,12 +37,18 @@
 .Dt ACCESS 2
 .Os BSD 4
 .Sh NAME
 .Dt ACCESS 2
 .Os BSD 4
 .Sh NAME

-.Nm access
+.Nm access ,
+.Nm faccessat

 .Nd check access permissions of a file or pathname
 .Sh SYNOPSIS
 .Fd #include <unistd.h>
 .Ft int
 .Nd check access permissions of a file or pathname
 .Sh SYNOPSIS
 .Fd #include <unistd.h>
 .Ft int

-.Fn access "const char *path" "int mode"
+.Fo access
+.Fa "const char *path"
+.Fa "int amode"
+.Fc
+.Ft int
+.Fn faccessat "int fd" "const char *path" "int mode" "int flag"

 .Sh DESCRIPTION
 The
 .Fn access
 .Sh DESCRIPTION
 The
 .Fn access


@@ -50,9 +56,9 @@ function checks the accessibility of the
 file named by
 .Fa path
 for the access permissions indicated by
 file named by
 .Fa path
 for the access permissions indicated by

-.Fa mode .
+.Fa amode .

 The value of
 The value of

-.Fa mode
+.Fa amode

 is the bitwise inclusive OR of the access permissions to be
 checked
 .Pf ( Dv R_OK
 is the bitwise inclusive OR of the access permissions to be
 checked
 .Pf ( Dv R_OK


@@ -72,6 +78,38 @@ and the real group access list
 (including the real group ID) are
 used in place of the effective ID for verifying permission.
 .Pp
 (including the real group ID) are
 used in place of the effective ID for verifying permission.
 .Pp

+The
+.Fn faccessat
+system call is equivalent to
+.Fn access
+except in the case where
+.Fa path
+specifies a relative path.
+In this case the file whose accessibility is to be determined is
+located relative to the directory associated with the file descriptor
+.Fa fd
+instead of the current working directory.
+If
+.Fn faccessat
+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 access .
+Values for
+.Fa flag
+are constructed by a bitwise-inclusive OR of flags from the following
+list, defined in
+.In fcntl.h :
+.Bl -tag -width indent
+.It Dv AT_EACCESS
+The checks for accessibility are performed using the effective user and group
+IDs instead of the real user and group ID as required in a call to
+.Fn access .
+.El
+.Pp

 Even if a process has appropriate privileges and indicates success for
 .Dv X_OK ,
 the file may not actually have execute permission bits set.
 Even if a process has appropriate privileges and indicates success for
 .Dv X_OK ,
 the file may not actually have execute permission bits set.


@@ -82,46 +120,87 @@ and
 .Sh RETURN VALUES
 If
 .Fa path
 .Sh RETURN VALUES
 If
 .Fa path

-cannot be found or if any of the desired access modes would
-not be granted, then a -1 value is returned; otherwise
-a 0 value is returned.
+cannot be found
+or if any of the desired access modes would not be granted,
+then a -1 value is returned and the global integer variable
+.Va errno
+is set to indicate the error.
+Otherwise, a 0 value is returned.

 .Sh ERRORS
 Access to the file is denied if:
 .Bl -tag -width Er
 .Sh ERRORS
 Access to the file is denied if:
 .Bl -tag -width Er

-.It Bq Er ENOTDIR
-A component of the path prefix is not a directory.
+.\" ==========
+.It Bq Er EACCES
+Permission bits of the file mode do not permit the requested access,
+or search permission is denied on a component of the path prefix.
+.Pp
+The owner of a file has permission checked
+with respect to the ``owner'' read, write, and execute mode bits,
+members of the file's group other than the owner have permission checked
+with respect to the ``group'' mode bits,
+and all others have permissions checked
+with respect to the ``other'' mode bits.
+.\" 
+.\" ==========
+.It Bq Er EFAULT
+.Fa Path
+points outside the process's allocated address space.
+.It Bq Er EINVAL
+An invalid value was specified for
+.Ar amode .
+.\" ==========
+.It Bq Er EIO
+An I/O error occurred while reading from or writing to the file system.
+.\" ==========
+.It Bq Er ELOOP
+Too many symbolic links were encountered in translating the pathname.
+.\" ==========

 .It Bq Er ENAMETOOLONG
 A component of a pathname exceeded 
 .Dv {NAME_MAX}
 characters, or an entire path name exceeded 
 .Dv {PATH_MAX}
 characters.
 .It Bq Er ENAMETOOLONG
 A component of a pathname exceeded 
 .Dv {NAME_MAX}
 characters, or an entire path name exceeded 
 .Dv {PATH_MAX}
 characters.

+.\" ==========

 .It Bq Er ENOENT
 The named file does not exist.
 .It Bq Er ENOENT
 The named file does not exist.

-.It Bq Er ELOOP
-Too many symbolic links were encountered in translating the pathname.
+.\" ==========
+.It Bq Er ENOTDIR
+A component of the path prefix is not a directory.
+.\" ==========

 .It Bq Er EROFS
 Write access is requested for a file on a read-only file system.
 .It Bq Er EROFS
 Write access is requested for a file on a read-only file system.

+.\" ==========

 .It Bq Er ETXTBSY
 Write access is requested for a pure procedure (shared text)
 .It Bq Er ETXTBSY
 Write access is requested for a pure procedure (shared text)

-file presently being executed.
-.It Bq Er EACCES
-Permission bits of the file mode do not permit the requested
-access, or search permission is denied on a component of the
-path prefix.  The owner of a file has permission checked with
-respect to the ``owner'' read, write, and execute mode bits,
-members of the file's group other than the owner have permission
-checked with respect to the ``group'' mode bits, and all
-others have permissions checked with respect to the ``other''
-mode bits.
-.It Bq Er EFAULT
-.Fa Path
-points outside the process's allocated address space.
-.It Bq Er EIO
-An I/O error occurred while reading from or writing to the file system.
+file that is presently being executed.
+.El
+.Pp
+Also, the
+.Fn faccessat
+system call 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.

 .It Bq Er EINVAL
 .It Bq Er EINVAL

-An invalid value was specified for
-.Ar mode .
+The value of the
+.Fa flag
+argument is not valid.
+.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 chmod 2 ,
 .El
 .Sh SEE ALSO
 .Xr chmod 2 ,


@@ -131,7 +210,10 @@ The
 .Fn access
 function conforms to 
 .St -p1003.1-90 .
 .Fn access
 function conforms to 
 .St -p1003.1-90 .

+The
+.Fn faccessat
+system call is expected to conform to POSIX.1-2008 .

 .Sh CAVEAT
 .Sh CAVEAT

-.Fn Access
+.Fn access

 is a potential security hole and
 should never be used.
 is a potential security hole and
 should never be used.