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 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 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 #pragma ident "%Z%%M% %I% %E% SMI" 35 36 #include <sys/param.h> 37 #include <sys/isa_defs.h> 38 #include <sys/types.h> 39 #include <sys/sysmacros.h> 40 #include <sys/cred.h> 41 #include <sys/systm.h> 42 #include <sys/errno.h> 43 #include <sys/pathname.h> 44 #include <sys/vnode.h> 45 #include <sys/file.h> 46 #include <sys/uio.h> 47 #include <sys/debug.h> 48 #include <fs/fs_subr.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 int estale_retry = 0; 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) && fs_need_estale_retry(estale_retry++)) 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 fs_need_estale_retry(estale_retry++)) 85 goto lookup; 86 return (set_errno(EINVAL)); 87 } 88 } 89 aiov.iov_base = buf; 90 aiov.iov_len = cnt; 91 auio.uio_iov = &aiov; 92 auio.uio_iovcnt = 1; 93 auio.uio_loffset = 0; 94 auio.uio_segflg = UIO_USERSPACE; 95 auio.uio_extflg = UIO_COPY_CACHED; 96 auio.uio_resid = cnt; 97 error = VOP_READLINK(vp, &auio, CRED()); 98 VN_RELE(vp); 99 if (error) { 100 if ((error == ESTALE) && fs_need_estale_retry(estale_retry++)) 101 goto lookup; 102 return (set_errno(error)); 103 } 104 return ((ssize_t)(cnt - auio.uio_resid)); 105 } 106 107 #ifdef _SYSCALL32_IMPL 108 /* 109 * readlink32() intentionally returns a ssize_t rather than ssize32_t; 110 * see the comments above read32 for details. 111 */ 112 113 ssize_t 114 readlink32(caddr32_t name, caddr32_t buf, size32_t count) 115 { 116 return ((ssize32_t)readlink((char *)(uintptr_t)name, 117 (char *)(uintptr_t)buf, (ssize32_t)count)); 118 } 119 120 #endif /* _SYSCALL32_IMPL */ 121