1 /** @file fileutils.cc
2 * @brief File and path manipulation routines.
3 */
4 /* Copyright (C) 2008 Lemur Consulting Ltd
5 * Copyright (C) 2008,2009,2010 Olly Betts
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include <config.h>
23
24 #include "fileutils.h"
25
26 #include <cstring>
27 #include <string>
28
29 using namespace std;
30
31 #ifdef __WIN32__
32 /// Return true iff a path starts with a drive letter.
33 static bool
has_drive(const string & path)34 has_drive(const string &path)
35 {
36 return (path.size() >= 2 && path[1] == ':');
37 }
38
39 /// Return true iff path is a UNCW path.
40 static bool
uncw_path(const string & path)41 uncw_path(const string & path)
42 {
43 return (path.size() >= 4 && memcmp(path.data(), "\\\\?\\", 4) == 0);
44 }
45
slash(char ch)46 inline bool slash(char ch)
47 {
48 return ch == '/' || ch == '\\';
49 }
50 #endif
51
52 void
resolve_relative_path(string & path,const string & base)53 resolve_relative_path(string & path, const string & base)
54 {
55 #ifndef __WIN32__
56 if (path.empty() || path[0] != '/') {
57 // path is relative.
58 string::size_type last_slash = base.rfind('/');
59 if (last_slash != string::npos)
60 path.insert(0, base, 0, last_slash + 1);
61 }
62 #else
63 // Microsoft Windows paths may begin with a drive letter but still be
64 // relative within that drive.
65 bool drive = has_drive(path);
66 string::size_type p = (drive ? 2 : 0);
67 bool absolute = (p != path.size() && slash(path[p]));
68
69 if (absolute) {
70 // If path is absolute and has a drive specifier, just return it.
71 if (drive)
72 return;
73
74 // If base has a drive specifier prepend that to path.
75 if (has_drive(base)) {
76 path.insert(0, base, 0, 2);
77 return;
78 }
79
80 // If base has a UNC (\\SERVER\\VOLUME) or \\?\ prefix, prepend that
81 // to path.
82 if (uncw_path(base)) {
83 string::size_type sl = 0;
84 if (base.size() >= 7 && memcmp(base.data() + 5, ":\\", 2) == 0) {
85 // "\\?\X:\"
86 sl = 6;
87 } else if (base.size() >= 8 &&
88 memcmp(base.data() + 4, "UNC\\", 4) == 0) {
89 // "\\?\UNC\server\volume\"
90 sl = base.find('\\', 8);
91 if (sl != string::npos)
92 sl = base.find('\\', sl + 1);
93 }
94 if (sl) {
95 // With the \\?\ prefix, '/' isn't recognised so change it
96 // to '\' in path.
97 string::iterator i;
98 for (i = path.begin(); i != path.end(); ++i) {
99 if (*i == '/')
100 *i = '\\';
101 }
102 path.insert(0, base, 0, sl);
103 }
104 } else if (base.size() >= 5 && slash(base[0]) && slash(base[1])) {
105 // Handle UNC base.
106 string::size_type sl = base.find_first_of("/\\", 2);
107 if (sl != string::npos) {
108 sl = base.find_first_of("/\\", sl + 1);
109 path.insert(0, base, 0, sl);
110 }
111 }
112 return;
113 }
114
115 // path is relative, so if it has no drive specifier or the same drive
116 // specifier as base, then we want to qualify it using base.
117 bool base_drive = has_drive(base);
118 if (!drive || (base_drive && (path[0] | 32) == (base[0] | 32))) {
119 string::size_type last_slash = base.find_last_of("/\\");
120 if (last_slash == string::npos && !drive && base_drive)
121 last_slash = 1;
122 if (last_slash != string::npos) {
123 string::size_type b = (drive && base_drive ? 2 : 0);
124 if (uncw_path(base)) {
125 // With the \\?\ prefix, '/' isn't recognised so change it
126 // to '\' in path.
127 string::iterator i;
128 for (i = path.begin(); i != path.end(); ++i) {
129 if (*i == '/')
130 *i = '\\';
131 }
132 }
133 path.insert(b, base, b, last_slash + 1 - b);
134 }
135 }
136 #endif
137 }
138