1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
24 */
25
26 /* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
27 /* All Rights Reserved */
28
29 /*
30 * Portions of this source code were derived from Berkeley 4.3 BSD
31 * under license from the Regents of the University of California.
32 */
33
34 #include <sys/param.h>
35 #include <sys/isa_defs.h>
36 #include <sys/types.h>
37 #include <sys/sysmacros.h>
38 #include <sys/cred.h>
39 #include <sys/systm.h>
40 #include <sys/errno.h>
41 #include <sys/pathname.h>
42 #include <sys/vnode.h>
43 #include <sys/file.h>
44 #include <sys/fcntl.h>
45 #include <sys/uio.h>
46 #include <sys/debug.h>
47 #include <fs/fs_subr.h>
48 #include <c2/audit.h>
49
50 /*
51 * Read the contents of a symbolic link.
52 */
53 ssize_t
readlinkat(int dfd,char * name,char * buf,size_t count)54 readlinkat(int dfd, char *name, char *buf, size_t count)
55 {
56 vnode_t *startvp;
57 vnode_t *vp;
58 struct iovec aiov;
59 struct uio auio;
60 int error;
61 struct vattr vattr;
62 ssize_t cnt;
63 int estale_retry = 0;
64
65 if ((cnt = (ssize_t)count) < 0)
66 return (set_errno(EINVAL));
67 if (name == NULL)
68 return (set_errno(EFAULT));
69 if ((error = fgetstartvp(dfd, name, &startvp)) != 0)
70 return (set_errno(error));
71
72 lookup:
73 if (AU_AUDITING() && startvp != NULL)
74 audit_setfsat_path(1);
75 if (error = lookupnameat(name, UIO_USERSPACE, NO_FOLLOW,
76 NULLVPP, &vp, startvp)) {
77 if (error == ESTALE && fs_need_estale_retry(estale_retry++))
78 goto lookup;
79 goto out;
80 }
81
82 if (vp->v_type != VLNK) {
83 /*
84 * Ask the underlying filesystem if it wants this
85 * object to look like a symlink at user-level.
86 */
87 vattr.va_mask = AT_TYPE;
88 error = VOP_GETATTR(vp, &vattr, 0, CRED(), NULL);
89 if (error || vattr.va_type != VLNK) {
90 VN_RELE(vp);
91 if ((error == ESTALE) &&
92 fs_need_estale_retry(estale_retry++))
93 goto lookup;
94 error = EINVAL;
95 goto out;
96 }
97 }
98 aiov.iov_base = buf;
99 aiov.iov_len = cnt;
100 auio.uio_iov = &aiov;
101 auio.uio_iovcnt = 1;
102 auio.uio_loffset = 0;
103 auio.uio_segflg = UIO_USERSPACE;
104 auio.uio_extflg = UIO_COPY_CACHED;
105 auio.uio_resid = cnt;
106 error = VOP_READLINK(vp, &auio, CRED(), NULL);
107 VN_RELE(vp);
108 if (error == ESTALE && fs_need_estale_retry(estale_retry++))
109 goto lookup;
110 out:
111 if (startvp != NULL)
112 VN_RELE(startvp);
113 if (error)
114 return (set_errno(error));
115 return ((ssize_t)(cnt - auio.uio_resid));
116 }
117
118 ssize_t
readlink(char * name,char * buf,size_t count)119 readlink(char *name, char *buf, size_t count)
120 {
121 return (readlinkat(AT_FDCWD, name, buf, count));
122 }
123
124 #ifdef _SYSCALL32_IMPL
125 /*
126 * readlink32() intentionally returns a ssize_t rather than ssize32_t;
127 * see the comments above read32 for details.
128 */
129
130 ssize_t
readlinkat32(int dfd,caddr32_t name,caddr32_t buf,size32_t count)131 readlinkat32(int dfd, caddr32_t name, caddr32_t buf, size32_t count)
132 {
133 return ((ssize32_t)readlinkat(dfd, (char *)(uintptr_t)name,
134 (char *)(uintptr_t)buf, (ssize32_t)count));
135 }
136
137 ssize_t
readlink32(caddr32_t name,caddr32_t buf,size32_t count)138 readlink32(caddr32_t name, caddr32_t buf, size32_t count)
139 {
140 return ((ssize32_t)readlinkat(AT_FDCWD, (char *)(uintptr_t)name,
141 (char *)(uintptr_t)buf, (ssize32_t)count));
142 }
143
144 #endif /* _SYSCALL32_IMPL */
145