Urlader/urlib.c

/*
 * Copyright (c) 2012 Marc Alexander Lehmann <schmorp@schmorp.de>
 * 
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 * 
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 * 
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

#include "urlib.h"

#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#ifdef _WIN32

  #include <windows.h>
  //#include <winbase.h>
  #include <shlobj.h>
  #include <shlwapi.h>
  #include <wininet.h>

  static DWORD dword;

  #define u_handle HANDLE
  #define u_invalid_handle 0
  #define u_valid(handle) (!!handle)

  #define u_setenv(name,value) SetEnvironmentVariable (name, value)
  #define u_mkdir(path) !CreateDirectory (path, NULL)
  #define u_chdir(path) !SetCurrentDirectory (path)
  #define u_rename(fr,to) !MoveFile (fr, to)
  #define u_open(path) CreateFile (path, GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_DELETE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL)
  #define u_creat(path,exec) CreateFile (path, GENERIC_WRITE, FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL)
  #define u_creat(path,exec) CreateFile (path, GENERIC_WRITE, FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL)
  #define u_close(handle) CloseHandle (handle)
  #define u_append(path,add) PathAppend (path, add)
  #define u_write(handle,data,len) (WriteFile (handle, data, len, &dword, 0) ? dword : -1)

  #define u_fsync(handle) FlushFileBuffers (handle)
  #define u_sync()

  #define u_lockfile(path) CreateFile (path, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)
  #define u_cloexec(handle)

#else

  #define _GNU_SOURCE 1
  #define _BSD_SOURCE 1
  // the above increases our chances of getting MAP_ANONYMOUS

  #include <sys/mman.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <unistd.h>
  #include <pwd.h>

  #if defined (MAP_ANON) && !defined (MAP_ANONYMOUS)
    #define MAP_ANONYMOUS MAP_ANON
  #endif

  #ifdef PATH_MAX
    #define MAX_PATH (PATH_MAX < 4096 ? 4096 : PATH_MAX)
  #else
    #define MAX_PATH 4096
  #endif

  #define u_handle int
  #define u_invalid_handle -1
  #define u_valid(fd) ((fd) >= 0)

  #define u_setenv(name,value) setenv (name, value, 1)
  #define u_mkdir(path) mkdir (path, 0777)
  #define u_chdir(path) chdir (path)
  #define u_rename(fr,to) rename (fr, to)
  #define u_open(path) open (path, O_RDONLY)
  #define u_creat(path,exec) open (path, O_WRONLY | O_CREAT | O_TRUNC, (exec) ? 0777 : 0666)
  #define u_close(handle) close (handle)
  #define u_append(path,add) strcat (strcat (path, "/"), add)
  #define u_write(handle,data,len) write (handle, data, len)

  // on a mostly idle system, a sync at the end is certainly faster, hope for the best
  #define u_fsync(handle)
  #define u_sync() sync ()

  #define u_lockfile(path) open (path, O_RDWR | O_CREAT, 0666)
  #define u_cloexec(handle) fcntl (handle, F_SETFD, FD_CLOEXEC)

#endif

#define u_16(ptr) (((ptr)[0] << 8) | (ptr)[1])
#define u_32(ptr) (((ptr)[0] << 24) | ((ptr)[1] << 16) | ((ptr)[2] << 8) | (ptr)[3])

static char currdir[MAX_PATH];
static char datadir[MAX_PATH];  // %AppData%/urlader
static char exe_dir[MAX_PATH];  // %AppData%/urlader/EXE_ID
static char execdir[MAX_PATH];  // %AppData%/urlader/EXE_ID/EXE_VER
static char exe_id[MAX_PATH];
static char exe_ver[MAX_PATH];

/////////////////////////////////////////////////////////////////////////////

static void
u_fatal (const char *msg)
{
#ifdef _WIN32
  MessageBox (0, msg, URLADER, 0);
#else
  write (2, URLADER ": ", sizeof (URLADER ": ") - 1);
  write (2, msg, strlen (msg));
  write (2, "\n", 1);
#endif

  _exit (1);
}

static void *
u_malloc (unsigned int size)
{
  void *addr;

  if (!size)
    return 0;

#ifdef _WIN32
  {
    HANDLE handle = CreateFileMapping (0, 0, PAGE_READWRITE, 0, size, NULL);

    addr = 0;
    if (handle)
      {
        addr = MapViewOfFile (handle, FILE_MAP_WRITE, 0, 0, size);
        CloseHandle (handle);
      }
  }
#elif defined (MAP_ANONYMOUS)
  addr = mmap (0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);

  if (addr == (void *)-1)
    addr = 0;
#else
  addr = malloc (size);
#endif

  if (!addr)
    u_fatal ("memory allocation failure, aborting.");

  return addr;
}

static void
u_free (void *addr, unsigned int size)
{
  if (!addr)
    return;

#ifdef _WIN32
  UnmapViewOfFile (addr);
#elif defined (MAP_ANONYMOUS)
  munmap (addr, size);
#else
  free (addr);
#endif
}

static void *
u_realloc (void *addr, unsigned int old_size, unsigned int new_size)
{
  void *addr2 = u_malloc (new_size);
  memcpy (addr2, addr, (new_size < old_size ? new_size : old_size));
  u_free (addr, old_size);

  return addr2;
}

static void *
u_mmap (u_handle h, unsigned int size)
{
  void *addr;

#ifdef _WIN32
  HANDLE handle = CreateFileMapping (h, 0, PAGE_READONLY, 0, size, NULL);

  if (!handle)
    return 0;

  addr = MapViewOfFile (handle, FILE_MAP_READ, 0, 0, size);

  CloseHandle (handle);
#else
  addr = mmap (0, size, PROT_READ, MAP_SHARED, h, 0);

  if (addr == (void *)-1)
    addr = 0;
#endif

  return addr;
}

static void
u_munmap (void *addr, unsigned int len)
{
#ifdef _WIN32
  UnmapViewOfFile (addr);
#else
  munmap (addr, len);
#endif
}

/////////////////////////////////////////////////////////////////////////////

typedef struct
{
  char *addr;
  unsigned int used;
  unsigned int size;
} u_dynbuf;

static void *
u_dynbuf_append (u_dynbuf *dynbuf, void *data, unsigned int len)
{
  char *dest;

  if ((dynbuf->used += len) > dynbuf->size)
    {
      unsigned int new_size = dynbuf->size ? dynbuf->size * 2 : 4096;
      dynbuf->addr = u_realloc (dynbuf->addr, dynbuf->size, new_size);
      dynbuf->size = new_size;
    }

  dest = dynbuf->addr + dynbuf->used - len;

  if (data)
    memcpy (dest, data, len);

  return dest;
}

/////////////////////////////////////////////////////////////////////////////

static void
u_set_datadir (void)
{
#ifdef _WIN32
  if (SHGetFolderPath (0, CSIDL_APPDATA | CSIDL_FLAG_CREATE, NULL, SHGFP_TYPE_CURRENT, datadir) != S_OK)
    u_fatal ("unable to find application data directory");

  u_mkdir (datadir);
  u_append (datadir, URLADER);

#else
  char *home = getenv ("HOME");

  if (!home)
    {
      struct passwd *pw;

      if ((pw = getpwuid (getuid ())))
        home = pw->pw_dir;
      else
        home = "/tmp";
    }

  u_mkdir (home);
  //strcat (strcat (strcpy (datadir, home), "/."), URLADER);
  sprintf (datadir, "%s/.%s", home, URLADER);
#endif

  u_setenv ("URLADER_DATADIR", datadir);
}

static void
u_set_exe_info (void)
{
  strcpy (exe_dir, datadir);
  u_append (exe_dir, exe_id);
  u_mkdir (exe_dir);

  strcpy (execdir, exe_dir);
  u_append (execdir, "i-");
  strcat (execdir, exe_ver);

  u_setenv ("URLADER_EXECDIR", execdir);
  u_setenv ("URLADER_EXE_ID" , exe_id);
  u_setenv ("URLADER_EXE_DIR", exe_dir);
  u_setenv ("URLADER_EXE_VER", exe_ver);
}

/////////////////////////////////////////////////////////////////////////////

static u_handle
u_lock (const char *path, int excl, int dowait)
{
  u_handle h;

  h = u_lockfile (path);
  if (!u_valid (h))
    return h;

  u_cloexec (h);

  for (;;)
    {
      int success;

      // acquire the lock
#ifdef _WIN32
      OVERLAPPED ov = { 0 };

      success = LockFileEx (h,
                            (excl ? LOCKFILE_EXCLUSIVE_LOCK : 0)
                            | (dowait ? 0 : LOCKFILE_FAIL_IMMEDIATELY),
                            0,
                            1, 0,
                            &ov);
#else
      struct flock lck = { 0 };

      lck.l_type   = excl ? F_WRLCK : F_RDLCK;
      lck.l_whence = SEEK_SET;
      lck.l_len    = 1;

      success = !fcntl (h, dowait ? F_SETLKW : F_SETLK, &lck);
#endif

      if (!success)
        break;

      // we have the lock, now verify that the lockfile still exists

#ifdef _WIN32
      // apparently, we have to open the file to get its info :(
      {
        BY_HANDLE_FILE_INFORMATION s1, s2;
        u_handle h2 = u_lockfile (path);
        if (!u_valid (h))
          break;

        success = GetFileInformationByHandle (h, &s1)
                  && GetFileInformationByHandle (h2, &s2);

        u_close (h2);

        if (!success)
          break;

        success = s1.dwVolumeSerialNumber == s2.dwVolumeSerialNumber
               && s1.nFileIndexHigh       == s2.nFileIndexHigh
               && s1.nFileIndexLow        == s2.nFileIndexLow;
      }
#else
      struct stat s1, s2;

      if (fstat (h, &s1) || stat (path, &s2))
        break;

      success = s1.st_dev == s2.st_dev
             && s1.st_ino == s2.st_ino;
#endif

      if (success)
        return h; // lock successfully acquired

      // files differ, close and retry - should be very rare
      u_close (h);
    }

  // failure
  u_close (h);
  return u_invalid_handle;
}

Revision:	1.6
Committed:	Tue Jan 17 18:38:37 2012 UTC (12 years, 3 months ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rel-1_0, rel-1_01, HEAD
Changes since 1.5:	+36 -0 lines
Log Message:	* empty log message *
#	Content
1	/*
2	* Copyright (c) 2012 Marc Alexander Lehmann <schmorp@schmorp.de>
3	*
4	* Redistribution and use in source and binary forms, with or without modifica-
5	* tion, are permitted provided that the following conditions are met:
6	*
7	* 1. Redistributions of source code must retain the above copyright notice,
8	* this list of conditions and the following disclaimer.
9	*
10	* 2. Redistributions in binary form must reproduce the above copyright
11	* notice, this list of conditions and the following disclaimer in the
12	* documentation and/or other materials provided with the distribution.
13	*
14	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
15	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
16	* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
17	* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
18	* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
20	* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
21	* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
22	* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
23	* OF THE POSSIBILITY OF SUCH DAMAGE.
24	*
25	* Alternatively, the contents of this file may be used under the terms of
26	* the GNU General Public License ("GPL") version 2 or any later version,
27	* in which case the provisions of the GPL are applicable instead of
28	* the above. If you wish to allow the use of your version of this file
29	* only under the terms of the GPL and not to allow others to use your
30	* version of this file under the BSD license, indicate your decision
31	* by deleting the provisions above and replace them with the notice
32	* and other provisions required by the GPL. If you do not delete the
33	* provisions above, a recipient may use your version of this file under
34	* either the BSD or the GPL.
35	*/
36
37	#include "urlib.h"
38
39	#include <fcntl.h>
40	#include <stdio.h>
41	#include <string.h>
42	#include <stdlib.h>
43
44	#ifdef _WIN32
45
46	#include <windows.h>
47	//#include <winbase.h>
48	#include <shlobj.h>
49	#include <shlwapi.h>
50	#include <wininet.h>
51
52	static DWORD dword;
53
54	#define u_handle HANDLE
55	#define u_invalid_handle 0
56	#define u_valid(handle) (!!handle)
57
58	#define u_setenv(name,value) SetEnvironmentVariable (name, value)
59	#define u_mkdir(path) !CreateDirectory (path, NULL)
60	#define u_chdir(path) !SetCurrentDirectory (path)
61	#define u_rename(fr,to) !MoveFile (fr, to)
62	#define u_open(path) CreateFile (path, GENERIC_READ, FILE_SHARE_READ \| FILE_SHARE_DELETE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL \| FILE_FLAG_SEQUENTIAL_SCAN, NULL)
63	#define u_creat(path,exec) CreateFile (path, GENERIC_WRITE, FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL \| FILE_FLAG_SEQUENTIAL_SCAN, NULL)
64	#define u_creat(path,exec) CreateFile (path, GENERIC_WRITE, FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL \| FILE_FLAG_SEQUENTIAL_SCAN, NULL)
65	#define u_close(handle) CloseHandle (handle)
66	#define u_append(path,add) PathAppend (path, add)
67	#define u_write(handle,data,len) (WriteFile (handle, data, len, &dword, 0) ? dword : -1)
68
69	#define u_fsync(handle) FlushFileBuffers (handle)
70	#define u_sync()
71
72	#define u_lockfile(path) CreateFile (path, GENERIC_READ \| GENERIC_WRITE, FILE_SHARE_READ \| FILE_SHARE_WRITE \| FILE_SHARE_DELETE, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL)
73	#define u_cloexec(handle)
74
75	#else
76
77	#define _GNU_SOURCE 1
78	#define _BSD_SOURCE 1
79	// the above increases our chances of getting MAP_ANONYMOUS
80
81	#include <sys/mman.h>
82	#include <sys/types.h>
83	#include <sys/stat.h>
84	#include <unistd.h>
85	#include <pwd.h>
86
87	#if defined (MAP_ANON) && !defined (MAP_ANONYMOUS)
88	#define MAP_ANONYMOUS MAP_ANON
89	#endif
90
91	#ifdef PATH_MAX
92	#define MAX_PATH (PATH_MAX < 4096 ? 4096 : PATH_MAX)
93	#else
94	#define MAX_PATH 4096
95	#endif
96
97	#define u_handle int
98	#define u_invalid_handle -1
99	#define u_valid(fd) ((fd) >= 0)
100
101	#define u_setenv(name,value) setenv (name, value, 1)
102	#define u_mkdir(path) mkdir (path, 0777)
103	#define u_chdir(path) chdir (path)
104	#define u_rename(fr,to) rename (fr, to)
105	#define u_open(path) open (path, O_RDONLY)
106	#define u_creat(path,exec) open (path, O_WRONLY \| O_CREAT \| O_TRUNC, (exec) ? 0777 : 0666)
107	#define u_close(handle) close (handle)
108	#define u_append(path,add) strcat (strcat (path, "/"), add)
109	#define u_write(handle,data,len) write (handle, data, len)
110
111	// on a mostly idle system, a sync at the end is certainly faster, hope for the best
112	#define u_fsync(handle)
113	#define u_sync() sync ()
114
115	#define u_lockfile(path) open (path, O_RDWR \| O_CREAT, 0666)
116	#define u_cloexec(handle) fcntl (handle, F_SETFD, FD_CLOEXEC)
117
118	#endif
119
120	#define u_16(ptr) (((ptr)[0] << 8) \| (ptr)[1])
121	#define u_32(ptr) (((ptr)[0] << 24) \| ((ptr)[1] << 16) \| ((ptr)[2] << 8) \| (ptr)[3])
122
123	static char currdir[MAX_PATH];
124	static char datadir[MAX_PATH]; // %AppData%/urlader
125	static char exe_dir[MAX_PATH]; // %AppData%/urlader/EXE_ID
126	static char execdir[MAX_PATH]; // %AppData%/urlader/EXE_ID/EXE_VER
127	static char exe_id[MAX_PATH];
128	static char exe_ver[MAX_PATH];
129
130	/////////////////////////////////////////////////////////////////////////////
131
132	static void
133	u_fatal (const char *msg)
134	{
135	#ifdef _WIN32
136	MessageBox (0, msg, URLADER, 0);
137	#else
138	write (2, URLADER ": ", sizeof (URLADER ": ") - 1);
139	write (2, msg, strlen (msg));
140	write (2, "\n", 1);
141	#endif
142
143	_exit (1);
144	}
145
146	static void *
147	u_malloc (unsigned int size)
148	{
149	void *addr;
150
151	if (!size)
152	return 0;
153
154	#ifdef _WIN32
155	{
156	HANDLE handle = CreateFileMapping (0, 0, PAGE_READWRITE, 0, size, NULL);
157
158	addr = 0;
159	if (handle)
160	{
161	addr = MapViewOfFile (handle, FILE_MAP_WRITE, 0, 0, size);
162	CloseHandle (handle);
163	}
164	}
165	#elif defined (MAP_ANONYMOUS)
166	addr = mmap (0, size, PROT_READ \| PROT_WRITE, MAP_PRIVATE \| MAP_ANON, -1, 0);
167
168	if (addr == (void *)-1)
169	addr = 0;
170	#else
171	addr = malloc (size);
172	#endif
173
174	if (!addr)
175	u_fatal ("memory allocation failure, aborting.");
176
177	return addr;
178	}
179
180	static void
181	u_free (void *addr, unsigned int size)
182	{
183	if (!addr)
184	return;
185
186	#ifdef _WIN32
187	UnmapViewOfFile (addr);
188	#elif defined (MAP_ANONYMOUS)
189	munmap (addr, size);
190	#else
191	free (addr);
192	#endif
193	}
194
195	static void *
196	u_realloc (void *addr, unsigned int old_size, unsigned int new_size)
197	{
198	void *addr2 = u_malloc (new_size);
199	memcpy (addr2, addr, (new_size < old_size ? new_size : old_size));
200	u_free (addr, old_size);
201
202	return addr2;
203	}
204
205	static void *
206	u_mmap (u_handle h, unsigned int size)
207	{
208	void *addr;
209
210	#ifdef _WIN32
211	HANDLE handle = CreateFileMapping (h, 0, PAGE_READONLY, 0, size, NULL);
212
213	if (!handle)
214	return 0;
215
216	addr = MapViewOfFile (handle, FILE_MAP_READ, 0, 0, size);
217
218	CloseHandle (handle);
219	#else
220	addr = mmap (0, size, PROT_READ, MAP_SHARED, h, 0);
221
222	if (addr == (void *)-1)
223	addr = 0;
224	#endif
225
226	return addr;
227	}
228
229	static void
230	u_munmap (void *addr, unsigned int len)
231	{
232	#ifdef _WIN32
233	UnmapViewOfFile (addr);
234	#else
235	munmap (addr, len);
236	#endif
237	}
238
239	/////////////////////////////////////////////////////////////////////////////
240
241	typedef struct
242	{
243	char *addr;
244	unsigned int used;
245	unsigned int size;
246	} u_dynbuf;
247
248	static void *
249	u_dynbuf_append (u_dynbuf dynbuf, void data, unsigned int len)
250	{
251	char *dest;
252
253	if ((dynbuf->used += len) > dynbuf->size)
254	{
255	unsigned int new_size = dynbuf->size ? dynbuf->size * 2 : 4096;
256	dynbuf->addr = u_realloc (dynbuf->addr, dynbuf->size, new_size);
257	dynbuf->size = new_size;
258	}
259
260	dest = dynbuf->addr + dynbuf->used - len;
261
262	if (data)
263	memcpy (dest, data, len);
264
265	return dest;
266	}
267
268	/////////////////////////////////////////////////////////////////////////////
269
270	static void
271	u_set_datadir (void)
272	{
273	#ifdef _WIN32
274	if (SHGetFolderPath (0, CSIDL_APPDATA \| CSIDL_FLAG_CREATE, NULL, SHGFP_TYPE_CURRENT, datadir) != S_OK)
275	u_fatal ("unable to find application data directory");
276
277	u_mkdir (datadir);
278	u_append (datadir, URLADER);
279
280	#else
281	char *home = getenv ("HOME");
282
283	if (!home)
284	{
285	struct passwd *pw;
286
287	if ((pw = getpwuid (getuid ())))
288	home = pw->pw_dir;
289	else
290	home = "/tmp";
291	}
292
293	u_mkdir (home);
294	//strcat (strcat (strcpy (datadir, home), "/."), URLADER);
295	sprintf (datadir, "%s/.%s", home, URLADER);
296	#endif
297
298	u_setenv ("URLADER_DATADIR", datadir);
299	}
300
301	static void
302	u_set_exe_info (void)
303	{
304	strcpy (exe_dir, datadir);
305	u_append (exe_dir, exe_id);
306	u_mkdir (exe_dir);
307
308	strcpy (execdir, exe_dir);
309	u_append (execdir, "i-");
310	strcat (execdir, exe_ver);
311
312	u_setenv ("URLADER_EXECDIR", execdir);
313	u_setenv ("URLADER_EXE_ID" , exe_id);
314	u_setenv ("URLADER_EXE_DIR", exe_dir);
315	u_setenv ("URLADER_EXE_VER", exe_ver);
316	}
317
318	/////////////////////////////////////////////////////////////////////////////
319
320	static u_handle
321	u_lock (const char *path, int excl, int dowait)
322	{
323	u_handle h;
324
325	h = u_lockfile (path);
326	if (!u_valid (h))
327	return h;
328
329	u_cloexec (h);
330
331	for (;;)
332	{
333	int success;
334
335	// acquire the lock
336	#ifdef _WIN32
337	OVERLAPPED ov = { 0 };
338
339	success = LockFileEx (h,
340	(excl ? LOCKFILE_EXCLUSIVE_LOCK : 0)
341	\| (dowait ? 0 : LOCKFILE_FAIL_IMMEDIATELY),
342	0,
343	1, 0,
344	&ov);
345	#else
346	struct flock lck = { 0 };
347
348	lck.l_type = excl ? F_WRLCK : F_RDLCK;
349	lck.l_whence = SEEK_SET;
350	lck.l_len = 1;
351
352	success = !fcntl (h, dowait ? F_SETLKW : F_SETLK, &lck);
353	#endif
354
355	if (!success)
356	break;
357
358	// we have the lock, now verify that the lockfile still exists
359
360	#ifdef _WIN32
361	// apparently, we have to open the file to get its info :(
362	{
363	BY_HANDLE_FILE_INFORMATION s1, s2;
364	u_handle h2 = u_lockfile (path);
365	if (!u_valid (h))
366	break;
367
368	success = GetFileInformationByHandle (h, &s1)
369	&& GetFileInformationByHandle (h2, &s2);
370
371	u_close (h2);
372
373	if (!success)
374	break;
375
376	success = s1.dwVolumeSerialNumber == s2.dwVolumeSerialNumber
377	&& s1.nFileIndexHigh == s2.nFileIndexHigh
378	&& s1.nFileIndexLow == s2.nFileIndexLow;
379	}
380	#else
381	struct stat s1, s2;
382
383	if (fstat (h, &s1) \|\| stat (path, &s2))
384	break;
385
386	success = s1.st_dev == s2.st_dev
387	&& s1.st_ino == s2.st_ino;
388	#endif
389
390	if (success)
391	return h; // lock successfully acquired
392
393	// files differ, close and retry - should be very rare
394	u_close (h);
395	}
396
397	// failure
398	u_close (h);
399	return u_invalid_handle;
400	}
401