summaryrefslogtreecommitdiff
path: root/libavutil/wchar_filename.h
blob: f36d9dfea3425c39198f32ea439aa9edd14c86be (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
/*
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef AVUTIL_WCHAR_FILENAME_H
#define AVUTIL_WCHAR_FILENAME_H

#ifdef _WIN32
#include <windows.h>
#include "mem.h"

av_warn_unused_result
static inline int utf8towchar(const char *filename_utf8, wchar_t **filename_w)
{
    int num_chars;
    num_chars = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, filename_utf8, -1, NULL, 0);
    if (num_chars <= 0) {
        *filename_w = NULL;
        return 0;
    }
    *filename_w = (wchar_t *)av_calloc(num_chars, sizeof(wchar_t));
    if (!*filename_w) {
        errno = ENOMEM;
        return -1;
    }
    MultiByteToWideChar(CP_UTF8, 0, filename_utf8, -1, *filename_w, num_chars);
    return 0;
}

/**
 * Checks for extended path prefixes for which normalization needs to be skipped.
 * see .NET6: PathInternal.IsExtended()
 * https://github.com/dotnet/runtime/blob/9260c249140ef90b4299d0fe1aa3037e25228518/src/libraries/Common/src/System/IO/PathInternal.Windows.cs#L165
 */
static inline int path_is_extended(const wchar_t *path)
{
    if (path[0] == L'\\' && (path[1] == L'\\' || path[1] == L'?') && path[2] == L'?' && path[3] == L'\\')
        return 1;

    return 0;
}

/**
 * Checks for a device path prefix.
 * see .NET6: PathInternal.IsDevice()
 * we don't check forward slashes and extended paths (as already done)
 * https://github.com/dotnet/runtime/blob/9260c249140ef90b4299d0fe1aa3037e25228518/src/libraries/Common/src/System/IO/PathInternal.Windows.cs#L132
 */
static inline int path_is_device_path(const wchar_t *path)
{
    if (path[0] == L'\\' && path[1] == L'\\' && path[2] == L'.' && path[3] == L'\\')
        return 1;

    return 0;
}

/**
 * Performs path normalization by calling GetFullPathNameW().
 * see .NET6: PathHelper.GetFullPathName()
 * https://github.com/dotnet/runtime/blob/2a99e18eedabcf1add064c099da59d9301ce45e0/src/libraries/System.Private.CoreLib/src/System/IO/PathHelper.Windows.cs#L70
 */
static inline int get_full_path_name(wchar_t **ppath_w)
{
    int num_chars;
    wchar_t *temp_w;

    num_chars = GetFullPathNameW(*ppath_w, 0, NULL, NULL);
    if (num_chars <= 0) {
        errno = EINVAL;
        return -1;
    }

    temp_w = (wchar_t *)av_calloc(num_chars, sizeof(wchar_t));
    if (!temp_w) {
        errno = ENOMEM;
        return -1;
    }

    num_chars = GetFullPathNameW(*ppath_w, num_chars, temp_w, NULL);
    if (num_chars <= 0) {
        av_free(temp_w);
        errno = EINVAL;
        return -1;
    }

    av_freep(ppath_w);
    *ppath_w = temp_w;

    return 0;
}

/**
 * Normalizes a Windows file or folder path.
 * Expansion of short paths (with 8.3 path components) is currently omitted
 * as it is not required for accessing long paths.
 * see .NET6: PathHelper.Normalize()
 * https://github.com/dotnet/runtime/blob/2a99e18eedabcf1add064c099da59d9301ce45e0/src/libraries/System.Private.CoreLib/src/System/IO/PathHelper.Windows.cs#L25
 */
static inline int path_normalize(wchar_t **ppath_w)
{
    int ret;

    if ((ret = get_full_path_name(ppath_w)) < 0)
        return ret;

    /* What .NET does at this point is to call PathHelper.TryExpandShortFileName()
     * in case the path contains a '~' character.
     * We don't need to do this as we don't need to normalize the file name
     * for presentation, and the extended path prefix works with 8.3 path
     * components as well
     */
    return 0;
}

/**
 * Adds an extended path or UNC prefix to longs paths or paths ending
 * with a space or a dot. (' ' or '.').
 * This function expects that the path has been normalized before by
 * calling path_normalize() and it doesn't check whether the path is
 * actually long (> MAX_PATH).
 * see .NET6: PathInternal.EnsureExtendedPrefix()
 * https://github.com/dotnet/runtime/blob/9260c249140ef90b4299d0fe1aa3037e25228518/src/libraries/Common/src/System/IO/PathInternal.Windows.cs#L107
 */
static inline int add_extended_prefix(wchar_t **ppath_w)
{
    const wchar_t *unc_prefix           = L"\\\\?\\UNC\\";
    const wchar_t *extended_path_prefix = L"\\\\?\\";
    const wchar_t *path_w               = *ppath_w;
    const size_t len                    = wcslen(path_w);
    wchar_t *temp_w;

    /* We're skipping the check IsPartiallyQualified() because
     * we expect to have called GetFullPathNameW() already. */
    if (len < 2 || path_is_extended(*ppath_w) || path_is_device_path(*ppath_w)) {
        return 0;
    }

    if (path_w[0] == L'\\' && path_w[1] == L'\\') {
        /* unc_prefix length is 8 plus 1 for terminating zeros,
         * we subtract 2 for the leading '\\' of the original path */
        temp_w = (wchar_t *)av_calloc(len - 2 + 8 + 1, sizeof(wchar_t));
        if (!temp_w) {
            errno = ENOMEM;
            return -1;
        }
        wcscpy(temp_w, unc_prefix);
        wcscat(temp_w, path_w + 2);
    } else {
        // The length of extended_path_prefix is 4 plus 1 for terminating zeros
        temp_w = (wchar_t *)av_calloc(len + 4 + 1, sizeof(wchar_t));
        if (!temp_w) {
            errno = ENOMEM;
            return -1;
        }
        wcscpy(temp_w, extended_path_prefix);
        wcscat(temp_w, path_w);
    }

    av_freep(ppath_w);
    *ppath_w = temp_w;

    return 0;
}

/**
 * Converts a file or folder path to wchar_t for use with Windows file
 * APIs. Paths with extended path prefix (either '\\?\' or \??\') are
 * left unchanged.
 * All other paths are normalized and converted to absolute paths.
 * Longs paths (>= MAX_PATH) are prefixed with the extended path or extended
 * UNC path prefix.
 * see .NET6: Path.GetFullPath() and Path.GetFullPathInternal()
 * https://github.com/dotnet/runtime/blob/2a99e18eedabcf1add064c099da59d9301ce45e0/src/libraries/System.Private.CoreLib/src/System/IO/Path.Windows.cs#L126
 */
static inline int get_extended_win32_path(const char *path, wchar_t **ppath_w)
{
    int ret;
    size_t len;

    if ((ret = utf8towchar(path, ppath_w)) < 0)
        return ret;

    if (path_is_extended(*ppath_w)) {
        /* Paths prefixed with '\\?\' or \??\' are considered normalized by definition.
         * Windows doesn't normalize those paths and neither should we.
         */
        return 0;
    }

    if ((ret = path_normalize(ppath_w)) < 0) {
        av_freep(ppath_w);
        return ret;
    }

    /* see .NET6: PathInternal.EnsureExtendedPrefixIfNeeded()
     * https://github.com/dotnet/runtime/blob/9260c249140ef90b4299d0fe1aa3037e25228518/src/libraries/Common/src/System/IO/PathInternal.Windows.cs#L92
     */
    len = wcslen(*ppath_w);
    if (len >= MAX_PATH) {
        if ((ret = add_extended_prefix(ppath_w)) < 0) {
            av_freep(ppath_w);
            return ret;
        }
    }

    return 0;
}

#endif

#endif /* AVUTIL_WCHAR_FILENAME_H */