1 /* 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2026 Dag-Erling Smørgrav 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include <sys/param.h> 29 #include <sys/sysctl.h> 30 31 #include <errno.h> 32 #include <libutil.h> 33 #include <paths.h> 34 #include <stdbool.h> 35 #include <stdlib.h> 36 #include <unistd.h> 37 38 #ifndef _PATH_LOCALBASE 39 #define _PATH_LOCALBASE "/usr/local" 40 #endif 41 42 /* 43 * Used in case of error; guaranteed to not be the start of a valid path 44 * name. Deliberately includes a trailing path separator so that any 45 * access will fail with ENOTDIR. 46 */ 47 #define INVALID_PREFIX "/dev/null/" 48 49 /* 50 * Copies a path from src to dst, which may point to the same buffer, 51 * while deduplicating path separators. Returns false if the path is not 52 * absolute or the result (including the terminating NUL) exceeds len 53 * characters. 54 */ 55 static bool 56 normalize(const char *src, char *dst, size_t len) 57 { 58 if (*src != '/' || len == 0) 59 return (false); 60 while (*src == '/') 61 src++; 62 do { 63 *dst++ = '/'; 64 if (--len == 0) 65 return (false); 66 while (*src != '\0' && *src != '/') { 67 *dst++ = *src++; 68 if (--len == 0) 69 return (false); 70 } 71 while (*src == '/') 72 src++; 73 } while (*src != '\0'); 74 *dst = '\0'; 75 return (true); 76 } 77 78 const char * 79 getlocalbase(void) 80 { 81 static const int oid[2] = { CTL_USER, USER_LOCALBASE }; 82 static char buf[MAXPATHLEN]; 83 static const char *localbase = NULL; 84 char *path; 85 size_t len = sizeof(buf); 86 87 if (localbase != NULL) 88 return (localbase); 89 90 /* If not privileged, try the environment first */ 91 if ((path = secure_getenv("LOCALBASE")) != NULL && *path != '\0') { 92 if (!normalize(path, buf, sizeof(buf))) 93 return (localbase = INVALID_PREFIX); 94 return (localbase = buf); 95 } 96 97 /* Next, try the sysctl variable */ 98 if (sysctl(oid, 2, buf, &len, NULL, 0) != 0) { 99 if (errno == ENOMEM) 100 return (localbase = INVALID_PREFIX); 101 } else if (*buf != '\0') { 102 if (!normalize(buf, buf, sizeof(buf))) 103 return (localbase = INVALID_PREFIX); 104 return (localbase = buf); 105 } 106 107 /* Fall back to the hardcoded default */ 108 return (localbase = _PATH_LOCALBASE); 109 } 110