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, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2005 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 /* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */ 28 /* All Rights Reserved */ 29 30 /* 31 * Portions of this source code were derived from Berkeley 4.3 BSD 32 * under license from the Regents of the University of California. 33 */ 34 35 #pragma ident "%Z%%M% %I% %E% SMI" 36 37 #include <sys/param.h> 38 #include <sys/isa_defs.h> 39 #include <sys/types.h> 40 #include <sys/sysmacros.h> 41 #include <sys/cred.h> 42 #include <sys/systm.h> 43 #include <sys/errno.h> 44 #include <sys/pathname.h> 45 #include <sys/vnode.h> 46 #include <sys/file.h> 47 #include <sys/uio.h> 48 #include <sys/debug.h> 49 50 /* 51 * Read the contents of a symbolic link. 52 */ 53 ssize_t 54 readlink(char *name, char *buf, size_t count) 55 { 56 vnode_t *vp; 57 struct iovec aiov; 58 struct uio auio; 59 int error; 60 struct vattr vattr; 61 ssize_t cnt; 62 63 if ((cnt = (ssize_t)count) < 0) 64 return (set_errno(EINVAL)); 65 66 lookup: 67 if (error = lookupname(name, UIO_USERSPACE, NO_FOLLOW, NULLVPP, &vp)) { 68 if (error == ESTALE) 69 goto lookup; 70 return (set_errno(error)); 71 } 72 73 if (vp->v_type != VLNK) { 74 /* 75 * Ask the underlying filesystem if it wants this 76 * object to look like a symlink at user-level. 77 */ 78 vattr.va_mask = AT_TYPE; 79 error = VOP_GETATTR(vp, &vattr, 0, CRED()); 80 if (error || vattr.va_type != VLNK) { 81 VN_RELE(vp); 82 if (error == ESTALE) 83 goto lookup; 84 return (set_errno(EINVAL)); 85 } 86 } 87 aiov.iov_base = buf; 88 aiov.iov_len = cnt; 89 auio.uio_iov = &aiov; 90 auio.uio_iovcnt = 1; 91 auio.uio_loffset = 0; 92 auio.uio_segflg = UIO_USERSPACE; 93 auio.uio_extflg = UIO_COPY_CACHED; 94 auio.uio_resid = cnt; 95 error = VOP_READLINK(vp, &auio, CRED()); 96 VN_RELE(vp); 97 if (error) { 98 if (error == ESTALE) 99 goto lookup; 100 return (set_errno(error)); 101 } 102 return ((ssize_t)(cnt - auio.uio_resid)); 103 } 104 105 #ifdef _SYSCALL32_IMPL 106 /* 107 * readlink32() intentionally returns a ssize_t rather than ssize32_t; 108 * see the comments above read32 for details. 109 */ 110 111 ssize_t 112 readlink32(caddr32_t name, caddr32_t buf, size32_t count) 113 { 114 return ((ssize32_t)readlink((char *)(uintptr_t)name, 115 (char *)(uintptr_t)buf, (ssize32_t)count)); 116 } 117 118 #endif /* _SYSCALL32_IMPL */ 119