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authorru <ru@FreeBSD.org>2001-10-11 15:27:53 +0000
committerru <ru@FreeBSD.org>2001-10-11 15:27:53 +0000
commit39c4ae6616188368ff3a82d0693b645e7b6529a6 (patch)
tree8d84802d331b461c0fcbbbaf4313bd6e5eb477ed
parentb0d7725e6d06b90f24cd57a55d75f334c3d5cce4 (diff)
downloadFreeBSD-src-39c4ae6616188368ff3a82d0693b645e7b6529a6.zip
FreeBSD-src-39c4ae6616188368ff3a82d0693b645e7b6529a6.tar.gz
- Bump document date for eaccess(2) addition.
- Mention ``eaccess'' in the NAME section. - Use intro(2) terminology. - Markup fixes. Reviewed by: rwatson
-rw-r--r--lib/libc/sys/access.262
1 files changed, 35 insertions, 27 deletions
diff --git a/lib/libc/sys/access.2 b/lib/libc/sys/access.2
index 2460aec..1673cd4 100644
--- a/lib/libc/sys/access.2
+++ b/lib/libc/sys/access.2
@@ -32,12 +32,12 @@
.\" @(#)access.2 8.2 (Berkeley) 4/1/94
.\" $FreeBSD$
.\"
-.Dd April 1, 1994
+.Dd September 21, 2001
.Dt ACCESS 2
.Os
.Sh NAME
-.Nm access
-.Nd check access permissions of a file or pathname
+.Nm access , eaccess
+.Nd check accessibility of a file
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
@@ -53,35 +53,42 @@ and
.Fn eaccess
functions check the accessibility of the
file named by
+the
.Fa path
+argument
for the access permissions indicated by
-.Fa mode .
+the
+.Fa mode
+argument.
The value of
.Fa mode
-is the bitwise inclusive OR of the access permissions to be
+is either the bitwise-inclusive OR of the access permissions to be
checked
-.Pf ( Dv R_OK
+.Dv ( R_OK
for read permission,
.Dv W_OK
-for write permission and
+for write permission, and
.Dv X_OK
-for execute/search permission) or the existence test,
-.Dv F_OK .
+for execute/search permission),
+or the existence test
+.Pq Dv F_OK .
.Pp
For additional information, see the
-.Dq File Access Permission
+.Sx "File Access Permission"
section of
.Xr intro 2 .
.Pp
+The
.Fn eaccess
-uses the effective user ID, group ID, and additional groups to authorize
-the request.
+call uses
+the effective user ID and the group access list
+to authorize the request;
+the
.Fn access
-uses
-the real user ID in place of the effective user ID
-and the real group access list
-(including the real group ID) are
-used in place of the effective ID for verifying permission.
+call uses
+the real user ID in place of the effective user ID,
+the real group ID in place of the effective group ID,
+and the rest of the group access list.
.Pp
Even if a process's real or effective user has appropriate privileges
and indicates success for
@@ -92,11 +99,7 @@ Likewise for
and
.Dv W_OK .
.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.
+.Rv -std
.Sh ERRORS
Access to the file is denied if:
.Bl -tag -width Er
@@ -119,7 +122,7 @@ Permission bits of the file mode do not permit the requested
access, or search permission is denied on a component of the
path prefix.
.It Bq Er EFAULT
-.Fa Path
+.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.
@@ -134,14 +137,19 @@ The
function call is expected to conform to
.St -p1003.1-90 .
.Sh CAVEAT
-.Fn Access
+The
+.Fn access
+call
is a potential security hole due to race conditions and
should never be used.
-Setuid and setgid applications should restore the effective uid or gid
+Set-user-ID and set-group-ID applications should restore the
+effective user or group ID,
and perform actions directly rather than use
.Fn access
-to simulate access checks for the real user of group id.
-.Fn Eaccess
+to simulate access checks for the real user or group ID.
+The
+.Fn eaccess
+call
likewise may be subject to races if used inappropriately.
.Sh HISTORY
An
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