1 /*- 2 * Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/ 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23 * SUCH DAMAGE. 24 */ 25 26 #include <sys/cdefs.h> 27 __FBSDID("$FreeBSD$"); 28 29 #include <libgen.h> 30 #include <stdbool.h> 31 #include <string.h> 32 33 char * 34 (dirname)(char *path) 35 { 36 const char *in, *prev, *begin, *end; 37 char *out; 38 size_t prevlen; 39 bool skipslash; 40 41 /* 42 * If path is a null pointer or points to an empty string, 43 * dirname() shall return a pointer to the string ".". 44 */ 45 if (path == NULL || *path == '\0') 46 return ((char *)"."); 47 48 /* Retain at least one leading slash character. */ 49 in = out = *path == '/' ? path + 1 : path; 50 51 skipslash = true; 52 prev = "."; 53 prevlen = 1; 54 for (;;) { 55 /* Extract the next pathname component. */ 56 while (*in == '/') 57 ++in; 58 begin = in; 59 while (*in != '/' && *in != '\0') 60 ++in; 61 end = in; 62 if (begin == end) 63 break; 64 65 /* 66 * Copy over the previous pathname component, except if 67 * it's dot. There is no point in retaining those. 68 */ 69 if (prevlen != 1 || *prev != '.') { 70 if (!skipslash) 71 *out++ = '/'; 72 skipslash = false; 73 memmove(out, prev, prevlen); 74 out += prevlen; 75 } 76 77 /* Preserve the pathname component for the next iteration. */ 78 prev = begin; 79 prevlen = end - begin; 80 } 81 82 /* 83 * If path does not contain a '/', then dirname() shall return a 84 * pointer to the string ".". 85 */ 86 if (out == path) 87 *out++ = '.'; 88 *out = '\0'; 89 return (path); 90 } 91