summaryrefslogtreecommitdiffstats
path: root/apps/plugins/windows_lnk.c
blob: 6ef1a6a3ac26e2c9fb59b49eb05b46988c585162 (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
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2017 Sebastian Leonhardt
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

#include "plugin.h"

/**
 *  Follow Windows shortcuts (*.lnk files) in Rockbox.
 *  If the destination is a file, it will be selected in the file browser,
 *  a directory will be entered.
 *  For now, only relative links are supported.
 */

/* a selection of link flags */
#define HAS_LINK_TARGET_ID_LIST     0x01
#define HAS_LINK_INFO               0x02
#define HAS_NAME                    0x04
#define HAS_RELATIVE_PATH           0x08
#define HAS_WORKING_DIR             0x10
#define HAS_ARGUMENTS               0x20
#define HAS_ICON_LOCATION           0x40
#define IS_UNICODE                  0x80
#define FORCE_NO_LINK_INFO         0x100
/* a selection of file attributes flags */
#define FILE_ATTRIBUTE_DIRECTORY    0x10
#define FILE_ATTRIBUTE_NORMAL       0x80


/**
 *  Read one byte from file
 *  \param  fd  file descriptor
 *  \param  *a  where the data should go
 *  \return     false if an error occured, true on success
 */
static bool read_byte(const int fd, unsigned char *a)
{
    if (!rb->read(fd, a, 1))
        return false;
    return true;
}

/**
 *  Read 16-bit word from file, respecting windows endianness (little endian)
 *  \param  fd  file descriptor
 *  \param  *a  where the data should go
 *  \return     false if an error occured, true on success
 */
static bool read_word(const int fd, int *a)
{
    unsigned char a1,a2;
    int r;

    r = read_byte(fd, &a1);
    if (!r)
        return false;
    r = read_byte(fd, &a2);
    if (!r)
        return false;
    *a = (a2<<8) + a1;
    return true;
}

/**
 *  Read 32-bit word from file, respecting windows endianness (little endian)
 *  \param  fd  file descriptor
 *  \param  *a  where the data should go
 *  \return     false if an error occured, true on success
 */
static bool read_lword(const int fd, uint32_t *a)
{
    int a1,a2;
    int r;

    r = read_word(fd, &a1);
    if (!r)
        return false;
    r = read_word(fd, &a2);
    if (!r)
        return false;
    *a = (a2<<16) + a1;
    return true;
}


/**
 *  Scan *.lnk file for relative link target
 *  \param  fd          file descriptor
 *  \param  link_target the extracted link destination
 *  \param  target_size available space for the extracted link (in bytes)
 *  \param  link_flags  the link flags are stored here
 *  \param  file_atts   file attributes are stored here
 *  \return             returns false if extraction failed.
 */
static bool extract_link_destination(const int fd,
            char *link_target, const int target_size,
            uint32_t *link_flags, uint32_t *file_atts)
{
    int r;

    /* Read ShellLinkHeader */
    uint32_t size;
    r = read_lword(fd, &size);
    if (!r) return false;
    if (size!=0x4c) {       /* header size MUST be 76 bytes */
        DEBUGF("unexpected header size 0x%08lx (must be 0x0000004c)\n", size);
        return false;
    }

    /* Skip LinkCLSID (class identifier) */
    rb->lseek(fd, 0x10, SEEK_CUR);
    /* We need the LinkFlags and File attribute (to see if target is a directory) */
    r = read_lword(fd, link_flags);
    if (!r) return false;
    r = read_lword(fd, file_atts);
    if (!r) return false;
    rb->lseek(fd, size, SEEK_SET);    /* Skip to end of header */

    /* For now we only support relative links, so we can exit right away
       if no relative link structure is present */
    if (!(*link_flags & HAS_RELATIVE_PATH)) {
        DEBUGF("Link doesn't have relative path information\n");
        return false;
    }

    /* Read (skip) LinkTargetIDList structure if present */
    if (*link_flags & HAS_LINK_TARGET_ID_LIST) {
        int size;
        if (!read_word(fd, &size))
            return false;
        rb->lseek(fd, size, SEEK_CUR);
    }

    /* Read (skip) LinkInfo structure if present */
    if (*link_flags & HAS_LINK_INFO) {
        uint32_t size;
        r = read_lword(fd, &size);
        if (!r) return false;
        rb->lseek(fd, size-4, SEEK_CUR);
    }

    /* String Data section */

    /* Read (skip) NAME_STRING StringData structure if present */
    if (*link_flags & HAS_NAME) {
        int ccount;
        if (!read_word(fd, &ccount))
            return false;
        if (*link_flags & IS_UNICODE)
            rb->lseek(fd, ccount*2, SEEK_CUR);
        else
            rb->lseek(fd, ccount, SEEK_CUR);
    }

    /* Read RELATIVE_PATH StringData structure if present */
    /* This is finally the data we are searching for! */
    if (*link_flags & HAS_RELATIVE_PATH) {
        int ccount;
        r = read_word(fd, &ccount);
        if (*link_flags & IS_UNICODE) {
            unsigned char utf16[4], utf8[10];
            link_target[0] = '\0';
            for (int i=0; i<ccount; ++i) {
                r = read_byte(fd, &utf16[0]);
                if (!r) return false;
                r = read_byte(fd, &utf16[1]);
                if (!r) return false;
                /* check for surrogate pair and read the second char */
                if (utf16[1] >= 0xD8 && utf16[1] < 0xE0) {
                    r = read_byte(fd, &utf16[2]);
                    if (!r) return false;
                    r = read_byte(fd, &utf16[3]);
                    if (!r) return false;
                    ++i;
                }
                char *ptr = rb->utf16LEdecode(utf16, utf8, 1);
                *ptr = '\0';
                rb->strlcat(link_target, utf8, target_size);
            }
        }
        else { /* non-unicode */
            if (ccount >= target_size) {
                DEBUGF("ERROR: link target filename exceeds size!");
                return false;
            }
            rb->read(fd, link_target, ccount);
            link_target[ccount] = '\0';
        }
    }

    /* convert from windows to unix subdir separators */
    for (int i=0; link_target[i] != '\0'; ++i) {
        if (link_target[i]=='\\')
            link_target[i] = '/';
    }

    return true;
}


/**
 * strip rightmost part of file/pathname to next '/', i.e. remove filename
 * or last subdirectory. Leaves a trailing '/' character.
 * \param   pathname    full path or filename
*/
static void strip_rightmost_part(char *pathname)
{
    for (int i = rb->strlen(pathname)-2; i >= 0; --i) {
        if (pathname[i] == '/') {
            pathname[i+1] = '\0'; /* cut off */
            return;
        }
    }
    pathname[0] = '\0';
}


/**
 * Combine link file's absolute path with relative link target to form
 * (absolute) link destination
 * \param   abs_path    full shortcut filename (including path)
 * \param   rel_path    the extracted relative link target
 * \param   max_len     maximum lengt of combined filename
 */
static void assemble_link_dest(char *const abs_path, char const *rel_path,
                                const size_t max_len)
{
    strip_rightmost_part(abs_path); /* cut off link filename */

    for (;;) {
        if (rb->strncmp(rel_path, "../", 3)==0) {
            rel_path += 3;
            strip_rightmost_part(abs_path);
        }
        else if (rb->strncmp(rel_path, "./", 2)==0) {
            rel_path += 2;
        }
        else
            break;
    }

    if (*rel_path=='/')
        ++rel_path;      /* avoid double '/' chars when concatenating */
    rb->strlcat(abs_path, rel_path, max_len);
}


/**
 *  Select the chosen file in the file browser. A directory (filename ending
 *  with '/') will be entered.
 *  \param  link_target link target to be selected in the browser
 *  \return             returns false if the target doesn't exist
 */
static bool goto_entry(char *link_target)
{
    DEBUGF("Trying to go to '%s'...\n", link_target);
    if (!rb->file_exists(link_target))
        return false;

    /* Set the browsers dirfilter to the global setting.
     * This is required in case the plugin was launched
     * from the plugins browser, in which case the
     * dirfilter is set to only display .rock files */
    rb->set_dirfilter(rb->global_settings->dirfilter);

    /* Change directory to the entry selected by the user */
    rb->set_current_file(link_target);
    return true;
}


enum plugin_status plugin_start(const void* void_parameter)
{
    char *link_filename;
    char extracted_link[MAX_PATH];
    char link_target[MAX_PATH];
    uint32_t lnk_flags;
    uint32_t file_atts;

    /* This is a viewer, so a parameter must have been specified */
    if (void_parameter == NULL) {
        rb->splash(HZ*3, "No *.lnk file selected");
        return PLUGIN_OK;
    }

    link_filename = (char*)void_parameter;
    DEBUGF("Shortcut filename: \"%s\"\n", link_filename);

    int fd = rb->open(link_filename, O_RDONLY);
    if (fd < 0) {
        DEBUGF("Can't open link file\n");
        rb->splashf(HZ*3, "Can't open link file!");
        return PLUGIN_OK;
    }

    if (!extract_link_destination(fd, extracted_link, sizeof(extracted_link),
                                   &lnk_flags, &file_atts)) {
        rb->close(fd);
        DEBUGF("Error in extract_link_destination()\n");
        rb->splashf(HZ*3, "Unsupported or erroneous link file format");
        return PLUGIN_OK;
    }
    rb->close(fd);
    DEBUGF("Shortcut destination: \"%s\"\n", extracted_link);

    rb->strcpy(link_target, link_filename);
    assemble_link_dest(link_target, extracted_link, sizeof(link_target));
    DEBUGF("Link absolute path: \"%s\"\n", link_target);

    /* if target is a directory, add '/' to the dir name,
       so that the directory gets entered instead of just highlighted */
    if (file_atts & FILE_ATTRIBUTE_DIRECTORY)
        if (link_target[rb->strlen(link_target)-1] != '/')
            rb->strlcat(link_target, "/", sizeof(link_target));

    if (!goto_entry(link_target)) {
        char *what;
        if (file_atts & FILE_ATTRIBUTE_DIRECTORY)
            what = "directory";
        else
            what = "file";
        rb->splashf(HZ*3, "Can't find %s %s", what, link_target);
        DEBUGF("Can't find %s %s", what, link_target);
        return PLUGIN_OK;
    }

    return PLUGIN_OK;
}