1 /* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
2 /* util/support/path.c - Portable path manipulation functions */
3 /*
4 * Copyright (C) 2011 by the Massachusetts Institute of Technology.
5 * All rights reserved.
6 *
7 * Export of this software from the United States of America may
8 * require a specific license from the United States Government.
9 * It is the responsibility of any person or organization contemplating
10 * export to obtain such a license before exporting.
11 *
12 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
13 * distribute this software and its documentation for any purpose and
14 * without fee is hereby granted, provided that the above copyright
15 * notice appear in all copies and that both that copyright notice and
16 * this permission notice appear in supporting documentation, and that
17 * the name of M.I.T. not be used in advertising or publicity pertaining
18 * to distribution of the software without specific, written prior
19 * permission. Furthermore if you modify this software you must label
20 * your software as modified software and not distribute it in such a
21 * fashion that it might be confused with the original M.I.T. software.
22 * M.I.T. makes no representations about the suitability of
23 * this software for any purpose. It is provided "as is" without express
24 * or implied warranty.
25 */
26
27 #include <k5-platform.h>
28
29 /* For testing purposes, use a different symbol for Windows path semantics. */
30 #ifdef _WIN32
31 #define WINDOWS_PATHS
32 #endif
33
34 /*
35 * This file implements a limited set of portable path manipulation functions.
36 * When in doubt about edge cases, we follow the Python os.path semantics.
37 */
38
39 #ifdef WINDOWS_PATHS
40 #define SEP '\\'
41 #define IS_SEPARATOR(c) ((c) == '\\' || (c) == '/')
42 #else
43 #define SEP '/'
44 #define IS_SEPARATOR(c) ((c) == '/')
45 #endif
46
47 /* Find the rightmost path separator in path, or NULL if there is none. */
48 static inline const char *
find_sep(const char * path)49 find_sep(const char *path)
50 {
51 #ifdef WINDOWS_PATHS
52 const char *slash, *backslash;
53
54 slash = strrchr(path, '/');
55 backslash = strrchr(path, '\\');
56 if (slash != NULL && backslash != NULL)
57 return (slash > backslash) ? slash : backslash;
58 else
59 return (slash != NULL) ? slash : backslash;
60 #else
61 return strrchr(path, '/');
62 #endif
63 }
64
65 /* XXX drive letter prefixes */
66 long
k5_path_split(const char * path,char ** parent_out,char ** basename_out)67 k5_path_split(const char *path, char **parent_out, char **basename_out)
68 {
69 const char *pathstart, *sep, *pend, *bstart;
70 char *parent = NULL, *basename = NULL;
71
72 if (parent_out != NULL)
73 *parent_out = NULL;
74 if (basename_out != NULL)
75 *basename_out = NULL;
76
77 pathstart = path;
78 #ifdef WINDOWS_PATHS
79 if (*path != '\0' && path[1] == ':')
80 pathstart = path + 2;
81 #endif
82
83 sep = find_sep(pathstart);
84 if (sep != NULL) {
85 bstart = sep + 1;
86 /* Strip off excess separators before the one we found. */
87 pend = sep;
88 while (pend > pathstart && IS_SEPARATOR(pend[-1]))
89 pend--;
90 /* But if we hit the start, keep the whole separator sequence. */
91 if (pend == pathstart)
92 pend = sep + 1;
93 } else {
94 bstart = pathstart;
95 pend = pathstart;
96 }
97
98 if (parent_out) {
99 parent = malloc(pend - path + 1);
100 if (parent == NULL)
101 return ENOMEM;
102 memcpy(parent, path, pend - path);
103 parent[pend - path] = '\0';
104 }
105 if (basename_out) {
106 basename = strdup(bstart);
107 if (basename == NULL) {
108 free(parent);
109 return ENOMEM;
110 }
111 }
112
113 if (parent_out)
114 *parent_out = parent;
115 if (basename_out)
116 *basename_out = basename;
117 return 0;
118 }
119
120 long
k5_path_join(const char * path1,const char * path2,char ** path_out)121 k5_path_join(const char *path1, const char *path2, char **path_out)
122 {
123 char *path, c;
124 int ret;
125
126 *path_out = NULL;
127 if (k5_path_isabs(path2) || *path1 == '\0') {
128 /* Discard path1 and return a copy of path2. */
129 path = strdup(path2);
130 if (path == NULL)
131 return ENOMEM;
132 } else {
133 /*
134 * Compose path1 and path2, adding a separator if path1 is non-empty
135 * there's no separator between them already. (*path2 can be a
136 * separator in the weird case where it starts with /: or \: on
137 * Windows, and Python doesn't insert a separator in this case.)
138 */
139 c = path1[strlen(path1) - 1];
140 if (IS_SEPARATOR(c) || IS_SEPARATOR(*path2))
141 ret = asprintf(&path, "%s%s", path1, path2);
142 else
143 ret = asprintf(&path, "%s%c%s", path1, SEP, path2);
144 if (ret < 0)
145 return ENOMEM;
146 }
147 *path_out = path;
148 return 0;
149 }
150
151 int
k5_path_isabs(const char * path)152 k5_path_isabs(const char *path)
153 {
154 #ifdef WINDOWS_PATHS
155 if (*path != '\0' && path[1] == ':')
156 path += 2;
157 return (*path == '/' || *path == '\\');
158 #else
159 return (*path == '/');
160 #endif
161 }
162