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 * Copyright 2021 OmniOS Community Edition (OmniOSce) Association. 26 */ 27 28 #include <sys/copyops.h> 29 #include <sys/errno.h> 30 #include <sys/kmem.h> 31 #include <sys/param.h> 32 #include <sys/pathname.h> 33 #include <sys/sysmacros.h> 34 #include <sys/systm.h> 35 #include <sys/types.h> 36 #include <sys/vnode.h> 37 38 int 39 getcwd(char *buf, size_t buflen) 40 { 41 int err; 42 char *kbuf; 43 size_t kbuflen; 44 45 /* 46 * If the buffer cannot accommodate one character and nul terminator, 47 * it is too small. 48 */ 49 if (buflen < 2) 50 return (set_errno(ERANGE)); 51 52 /* 53 * The user should be able to specify any size buffer, but we don't want 54 * to arbitrarily allocate huge kernel buffers just because the user 55 * requests it. So we'll start with MAXPATHLEN (which should hold any 56 * normal path), and only increase it if we fail with 57 * ERANGE / ENAMETOOLONG. 58 * 59 * To protect against unbounded memory usage, cap to kmem_max_cached. 60 * This is far bigger than the length of any practical path on the 61 * system, and avoids allocating memory from the kmem_oversized arena. 62 */ 63 kbuflen = MIN(buflen, MAXPATHLEN); 64 65 while (kbuflen <= kmem_max_cached) { 66 kbuf = kmem_alloc(kbuflen, KM_SLEEP); 67 68 if (((err = dogetcwd(kbuf, kbuflen)) == 0) && 69 (copyout(kbuf, buf, strlen(kbuf) + 1) != 0)) { 70 err = EFAULT; 71 } 72 73 kmem_free(kbuf, kbuflen); 74 75 /* 76 * dogetcwd() inconsistently returns ERANGE or ENAMETOOLONG 77 * depending on whether it calls dirtopath() and then whether 78 * the subsequent operations run out of space whilst 79 * evaluating a cached vnode path or otherwise. 80 */ 81 if (err == ENAMETOOLONG || err == ERANGE) { 82 /* For some reason, getcwd() uses ERANGE. */ 83 err = ERANGE; 84 /* 85 * If the user's buffer really was too small, give up. 86 */ 87 if (kbuflen == buflen) 88 break; 89 kbuflen = MIN(kbuflen * 2, buflen); 90 } else { 91 break; 92 } 93 } 94 95 return ((err != 0) ? set_errno(err) : 0); 96 } 97