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/ioreq.h> 49 #include <sys/debug.h> 50 51 /* 52 * Read the contents of a symbolic link. 53 */ 54 ssize_t 55 readlink(char *name, char *buf, size_t count) 56 { 57 vnode_t *vp; 58 struct iovec aiov; 59 struct uio auio; 60 int error; 61 struct vattr vattr; 62 ssize_t cnt; 63 64 if ((cnt = (ssize_t)count) < 0) 65 return (set_errno(EINVAL)); 66 67 lookup: 68 if (error = lookupname(name, UIO_USERSPACE, NO_FOLLOW, NULLVPP, &vp)) { 69 if (error == ESTALE) 70 goto lookup; 71 return (set_errno(error)); 72 } 73 74 if (vp->v_type != VLNK) { 75 /* 76 * Ask the underlying filesystem if it wants this 77 * object to look like a symlink at user-level. 78 */ 79 vattr.va_mask = AT_TYPE; 80 error = VOP_GETATTR(vp, &vattr, 0, CRED()); 81 if (error || vattr.va_type != VLNK) { 82 VN_RELE(vp); 83 if (error == ESTALE) 84 goto lookup; 85 return (set_errno(EINVAL)); 86 } 87 } 88 aiov.iov_base = buf; 89 aiov.iov_len = cnt; 90 auio.uio_iov = &aiov; 91 auio.uio_iovcnt = 1; 92 auio.uio_loffset = 0; 93 auio.uio_segflg = UIO_USERSPACE; 94 auio.uio_extflg = UIO_COPY_CACHED; 95 auio.uio_resid = cnt; 96 error = VOP_READLINK(vp, &auio, CRED()); 97 VN_RELE(vp); 98 if (error) { 99 if (error == ESTALE) 100 goto lookup; 101 return (set_errno(error)); 102 } 103 return ((ssize_t)(cnt - auio.uio_resid)); 104 } 105 106 #ifdef _SYSCALL32_IMPL 107 /* 108 * readlink32() intentionally returns a ssize_t rather than ssize32_t; 109 * see the comments above read32 for details. 110 */ 111 112 ssize_t 113 readlink32(caddr32_t name, caddr32_t buf, size32_t count) 114 { 115 return ((ssize32_t)readlink((char *)(uintptr_t)name, 116 (char *)(uintptr_t)buf, (ssize32_t)count)); 117 } 118 119 #endif /* _SYSCALL32_IMPL */ 120