FFmpeg
wchar_filename.h
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #ifndef AVUTIL_WCHAR_FILENAME_H
20 #define AVUTIL_WCHAR_FILENAME_H
21 
22 #ifdef _WIN32
23 
24 #define WIN32_LEAN_AND_MEAN
25 #include <windows.h>
26 #include "mem.h"
27 
29 static inline int utf8towchar(const char *filename_utf8, wchar_t **filename_w)
30 {
31  int num_chars;
32  num_chars = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, filename_utf8, -1, NULL, 0);
33  if (num_chars <= 0) {
34  *filename_w = NULL;
35  errno = EINVAL;
36  return -1;
37  }
38  *filename_w = (wchar_t *)av_calloc(num_chars, sizeof(wchar_t));
39  if (!*filename_w) {
40  errno = ENOMEM;
41  return -1;
42  }
43  MultiByteToWideChar(CP_UTF8, 0, filename_utf8, -1, *filename_w, num_chars);
44  return 0;
45 }
46 
48 static inline int wchartocp(unsigned int code_page, const wchar_t *filename_w,
49  char **filename)
50 {
51  DWORD flags = code_page == CP_UTF8 ? WC_ERR_INVALID_CHARS : 0;
52  int num_chars = WideCharToMultiByte(code_page, flags, filename_w, -1,
53  NULL, 0, NULL, NULL);
54  if (num_chars <= 0) {
55  *filename = NULL;
56  errno = EINVAL;
57  return -1;
58  }
59  *filename = (char*)av_malloc_array(num_chars, sizeof *filename);
60  if (!*filename) {
61  errno = ENOMEM;
62  return -1;
63  }
64  WideCharToMultiByte(code_page, flags, filename_w, -1,
65  *filename, num_chars, NULL, NULL);
66  return 0;
67 }
68 
70 static inline int wchartoutf8(const wchar_t *filename_w, char **filename)
71 {
72  return wchartocp(CP_UTF8, filename_w, filename);
73 }
74 
76 static inline int wchartoansi(const wchar_t *filename_w, char **filename)
77 {
78  return wchartocp(CP_ACP, filename_w, filename);
79 }
80 
82 static inline int utf8toansi(const char *filename_utf8, char **filename)
83 {
84  wchar_t *filename_w = NULL;
85  int ret = -1;
86  if (utf8towchar(filename_utf8, &filename_w))
87  return -1;
88 
89  if (!filename_w) {
90  *filename = NULL;
91  return 0;
92  }
93 
94  ret = wchartoansi(filename_w, filename);
95  av_free(filename_w);
96  return ret;
97 }
98 
99 /**
100  * Checks for extended path prefixes for which normalization needs to be skipped.
101  * see .NET6: PathInternal.IsExtended()
102  * https://github.com/dotnet/runtime/blob/9260c249140ef90b4299d0fe1aa3037e25228518/src/libraries/Common/src/System/IO/PathInternal.Windows.cs#L165
103  */
104 static inline int path_is_extended(const wchar_t *path)
105 {
106  if (path[0] == L'\\' && (path[1] == L'\\' || path[1] == L'?') && path[2] == L'?' && path[3] == L'\\')
107  return 1;
108 
109  return 0;
110 }
111 
112 /**
113  * Checks for a device path prefix.
114  * see .NET6: PathInternal.IsDevice()
115  * we don't check forward slashes and extended paths (as already done)
116  * https://github.com/dotnet/runtime/blob/9260c249140ef90b4299d0fe1aa3037e25228518/src/libraries/Common/src/System/IO/PathInternal.Windows.cs#L132
117  */
118 static inline int path_is_device_path(const wchar_t *path)
119 {
120  if (path[0] == L'\\' && path[1] == L'\\' && path[2] == L'.' && path[3] == L'\\')
121  return 1;
122 
123  return 0;
124 }
125 
126 /**
127  * Performs path normalization by calling GetFullPathNameW().
128  * see .NET6: PathHelper.GetFullPathName()
129  * https://github.com/dotnet/runtime/blob/2a99e18eedabcf1add064c099da59d9301ce45e0/src/libraries/System.Private.CoreLib/src/System/IO/PathHelper.Windows.cs#L70
130  */
131 static inline int get_full_path_name(wchar_t **ppath_w)
132 {
133  int num_chars;
134  wchar_t *temp_w;
135 
136  num_chars = GetFullPathNameW(*ppath_w, 0, NULL, NULL);
137  if (num_chars <= 0) {
138  errno = EINVAL;
139  return -1;
140  }
141 
142  temp_w = (wchar_t *)av_calloc(num_chars, sizeof(wchar_t));
143  if (!temp_w) {
144  errno = ENOMEM;
145  return -1;
146  }
147 
148  num_chars = GetFullPathNameW(*ppath_w, num_chars, temp_w, NULL);
149  if (num_chars <= 0) {
150  av_free(temp_w);
151  errno = EINVAL;
152  return -1;
153  }
154 
155  av_freep(ppath_w);
156  *ppath_w = temp_w;
157 
158  return 0;
159 }
160 
161 /**
162  * Normalizes a Windows file or folder path.
163  * Expansion of short paths (with 8.3 path components) is currently omitted
164  * as it is not required for accessing long paths.
165  * see .NET6: PathHelper.Normalize()
166  * https://github.com/dotnet/runtime/blob/2a99e18eedabcf1add064c099da59d9301ce45e0/src/libraries/System.Private.CoreLib/src/System/IO/PathHelper.Windows.cs#L25
167  */
168 static inline int path_normalize(wchar_t **ppath_w)
169 {
170  int ret;
171 
172  if ((ret = get_full_path_name(ppath_w)) < 0)
173  return ret;
174 
175  /* What .NET does at this point is to call PathHelper.TryExpandShortFileName()
176  * in case the path contains a '~' character.
177  * We don't need to do this as we don't need to normalize the file name
178  * for presentation, and the extended path prefix works with 8.3 path
179  * components as well
180  */
181  return 0;
182 }
183 
184 /**
185  * Adds an extended path or UNC prefix to longs paths or paths ending
186  * with a space or a dot. (' ' or '.').
187  * This function expects that the path has been normalized before by
188  * calling path_normalize() and it doesn't check whether the path is
189  * actually long (> MAX_PATH).
190  * see .NET6: PathInternal.EnsureExtendedPrefix()
191  * https://github.com/dotnet/runtime/blob/9260c249140ef90b4299d0fe1aa3037e25228518/src/libraries/Common/src/System/IO/PathInternal.Windows.cs#L107
192  */
193 static inline int add_extended_prefix(wchar_t **ppath_w)
194 {
195  const wchar_t *unc_prefix = L"\\\\?\\UNC\\";
196  const wchar_t *extended_path_prefix = L"\\\\?\\";
197  const wchar_t *path_w = *ppath_w;
198  const size_t len = wcslen(path_w);
199  wchar_t *temp_w;
200 
201  /* We're skipping the check IsPartiallyQualified() because
202  * we expect to have called GetFullPathNameW() already. */
203  if (len < 2 || path_is_extended(*ppath_w) || path_is_device_path(*ppath_w)) {
204  return 0;
205  }
206 
207  if (path_w[0] == L'\\' && path_w[1] == L'\\') {
208  /* unc_prefix length is 8 plus 1 for terminating zeros,
209  * we subtract 2 for the leading '\\' of the original path */
210  temp_w = (wchar_t *)av_calloc(len - 2 + 8 + 1, sizeof(wchar_t));
211  if (!temp_w) {
212  errno = ENOMEM;
213  return -1;
214  }
215  wcscpy(temp_w, unc_prefix);
216  wcscat(temp_w, path_w + 2);
217  } else {
218  // The length of extended_path_prefix is 4 plus 1 for terminating zeros
219  temp_w = (wchar_t *)av_calloc(len + 4 + 1, sizeof(wchar_t));
220  if (!temp_w) {
221  errno = ENOMEM;
222  return -1;
223  }
224  wcscpy(temp_w, extended_path_prefix);
225  wcscat(temp_w, path_w);
226  }
227 
228  av_freep(ppath_w);
229  *ppath_w = temp_w;
230 
231  return 0;
232 }
233 
234 /**
235  * Converts a file or folder path to wchar_t for use with Windows file
236  * APIs. Paths with extended path prefix (either '\\?\' or \??\') are
237  * left unchanged.
238  * All other paths are normalized and converted to absolute paths.
239  * Longs paths (>= MAX_PATH) are prefixed with the extended path or extended
240  * UNC path prefix.
241  * see .NET6: Path.GetFullPath() and Path.GetFullPathInternal()
242  * https://github.com/dotnet/runtime/blob/2a99e18eedabcf1add064c099da59d9301ce45e0/src/libraries/System.Private.CoreLib/src/System/IO/Path.Windows.cs#L126
243  */
244 static inline int get_extended_win32_path(const char *path, wchar_t **ppath_w)
245 {
246  int ret;
247  size_t len;
248 
249  if ((ret = utf8towchar(path, ppath_w)) < 0)
250  return ret;
251 
252  if (path_is_extended(*ppath_w)) {
253  /* Paths prefixed with '\\?\' or \??\' are considered normalized by definition.
254  * Windows doesn't normalize those paths and neither should we.
255  */
256  return 0;
257  }
258 
259  if ((ret = path_normalize(ppath_w)) < 0) {
260  av_freep(ppath_w);
261  return ret;
262  }
263 
264  /* see .NET6: PathInternal.EnsureExtendedPrefixIfNeeded()
265  * https://github.com/dotnet/runtime/blob/9260c249140ef90b4299d0fe1aa3037e25228518/src/libraries/Common/src/System/IO/PathInternal.Windows.cs#L92
266  */
267  len = wcslen(*ppath_w);
268  if (len >= MAX_PATH) {
269  if ((ret = add_extended_prefix(ppath_w)) < 0) {
270  av_freep(ppath_w);
271  return ret;
272  }
273  }
274 
275  return 0;
276 }
277 
278 #endif
279 
280 #endif /* AVUTIL_WCHAR_FILENAME_H */
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