Urlader/urlader.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 "urlib.c"

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <time.h>

#include "liblzf/lzf_d.c"

/* some simple? dynamic memory management for paths might save ltos of ram */
static u_handle pack_handle;
static u_handle lock_handle;
static char tmppath[MAX_PATH];

static int exe_argc;
static u_dynbuf exe_argv;
static u_dynbuf exe_args; /* actual arguments strings copied here */

static void
tmpdir (const char *dir)
{
  static int cnt;

  for (;;)
    {
//      #ifdef _WIN32
//        sprintf (tmppath, "%s/%x_%x.tmp", dir, (unsigned int)GetCurrentProcessId (), ++cnt);
//      #else
        sprintf (tmppath, "%s/t-%x_%x.tmp", dir, (unsigned int)getpid ()             , ++cnt);
//      #endif

      if (!u_mkdir (tmppath))
        return;
    }
}

static void
systemv (const char *const argv[])
{
#ifdef _WIN32
  _spawnv (P_WAIT, argv [0], argv);
#else
  pid_t pid = fork ();

  if (pid < 0)
    u_fatal ("fork failure");

  if (!pid)
    {
      execv (argv [0], (void *)argv);
      _exit (124);
    }

  int status;
  waitpid (pid, &status, 0);
#endif
}

static void
deltree (const char *path)
{
  #ifdef _WIN32
    char buf[MAX_PATH * 2 + 64];
    const char *argv[] = { getenv ("COMSPEC"), "/c", "rd", "/s", "/q", buf, 0 };
    sprintf (buf, "\"%s\"", path);
  #else
    const char *argv[] = { "/bin/rm", "-rf", path, 0 };
  #endif
  systemv (argv);
}

static char *pack_base, *pack_end;
static struct u_pack_tail *pack_tail;
static struct u_pack_hdr *pack_cur;
static char *scratch;
static unsigned int scratch_size;

#define PACK_NAME ((char *)(pack_cur + 1))
#define PACK_DATA (PACK_NAME + u_16 (pack_cur->namelen) + 1)
#define PACK_VALID pack_cur->type

static void
pack_next (void)
{
  unsigned int d = u_32 (pack_cur->datalen);

  pack_cur = (struct u_pack_hdr *)(PACK_DATA + d);
}

static void
pack_unmap (void)
{
  if (pack_base)
    {
      u_munmap (pack_base, pack_end - pack_base);
      pack_base = 0;
    }

  if (scratch)
    {
      u_free (scratch, scratch_size);
      scratch = 0;
    }
}

static int
pack_map (void)
{
  char *addr;
  unsigned int size;

#ifdef _WIN32
  BY_HANDLE_FILE_INFORMATION fi;

  if (!GetFileInformationByHandle (pack_handle, &fi))
    return 0;

  size = fi.nFileSizeLow;
#else
  size = lseek (pack_handle, 0, SEEK_END);
#endif

  addr = u_mmap (pack_handle, size);
  if (!addr)
    return 0;

  /*pack_unmap ();*/

  pack_base = addr;
  pack_end  = pack_base + size;

  pack_tail = (void *)(pack_end - sizeof (*pack_tail));

  if (memcmp (pack_tail->magic, TAIL_MAGIC, sizeof (TAIL_MAGIC) - 1))
    return 0;

  pack_cur = (struct u_pack_hdr *)(pack_end - u_32 (pack_tail->size));

  if (pack_cur->type != T_META)
    return 0;

  scratch = u_malloc (scratch_size = u_32 (pack_tail->max_uncompressed));
  if (!scratch)
    return 0;

  return 1;
}

static void
add_arg (char *arg, unsigned int len)
{
  char *addr = u_dynbuf_append (&exe_args,  arg, len);
  u_dynbuf_append (&exe_argv, &addr, sizeof (addr));
}

static void
load (void)
{
  strcpy (exe_id , PACK_NAME);
  strcpy (exe_ver, PACK_DATA);
  u_set_exe_info ();

  if (u_chdir (exe_dir))
    u_fatal ("unable to change to application data directory");

  u_handle h = u_open ("override");
  if (u_valid (h))
    {
      u_handle oh = pack_handle;

      pack_unmap ();
      pack_handle = h;

      if (pack_map ()
          && strcmp (exe_id , PACK_NAME) == 0
          && strcmp (exe_ver, PACK_DATA) <= 0)
        u_setenv ("URLADER_OVERRIDE", "override");
      else
        {
          pack_unmap ();
          pack_handle = oh;
          oh = h;
          pack_map ();
        }

      u_close (oh);
    }

  strcpy (exe_ver, PACK_DATA);
  u_set_exe_info ();
  pack_next ();

  for (;;)
    {
      if (pack_cur->type == T_ENV)
        u_setenv (PACK_NAME, PACK_DATA);
      else if (pack_cur->type == T_ARG)
        add_arg (PACK_NAME, u_16 (pack_cur->namelen) + 1);
      else
        break;

      pack_next ();
    }
 
done_env_arg:

  strcat (strcpy (tmppath, execdir), ".lck");
  lock_handle = u_lock (tmppath, 0, 1);
  if (!lock_handle)
    u_fatal ("unable to lock application instance");

  if (access (execdir, F_OK))
    {
      // does not exist yet, so unpack and move
      tmpdir (exe_dir);

      if (u_chdir (tmppath))
        u_fatal ("unable to change to new instance directory");

      for (;;)
        {
          switch (pack_cur->type)
            {
              case T_DIR:
                u_mkdir (PACK_NAME);
                break;

              case T_FILE:
                {
                  u_handle h = u_creat (PACK_NAME, pack_cur->flags & F_EXEC);
                  unsigned int dlen, len = u_32 (pack_cur->datalen);
                  char *data = PACK_DATA;

                  if (pack_cur->flags & F_LZF)
                    if (dlen = lzf_decompress (data, len, scratch, scratch_size))
                      {
                        data = scratch;
                        len  = dlen;
                      }
                    else
                      u_fatal ("unable to uncompress file data - pack corrupted?");

                  if (!u_valid (h))
                    u_fatal ("unable to unpack file from packfile - disk full?");

                  if (u_write (h, data, len) != len)
                    u_fatal ("unable to unpack file from packfile - disk full?");

                  u_fsync (h);
                  u_close (h);
                }
                break;

              case T_NULL:
                goto done;
            }

          pack_next ();
        }

done:
      if (u_chdir (datadir))
        u_fatal ("unable to change to data directory");

      u_sync ();

      if (u_rename (tmppath, execdir))
        deltree (tmppath); // if move fails, delete new, assume other process created it independently
    }

  pack_unmap ();
  u_close (pack_handle);

  if (u_chdir (execdir))
    u_fatal ("unable to change to application instance directory");

  u_setenv ("URLADER_VERSION", URLADER_VERSION);

#if 0
  // yes, this is overkill
  u_setenv ("SHLIB_PATH"        , execdir); // hpux
  u_setenv ("LIBPATH"           , execdir); // aix
  u_setenv ("LD_LIBRARY_PATH"   , execdir); // most elf systems
  u_setenv ("LD_LIBRARY_PATH_32", execdir); // solaris
  u_setenv ("LD_LIBRARY_PATH_64", execdir); // solaris
  u_setenv ("LD_LIBRARYN32_PATH", execdir); // irix
  u_setenv ("LD_LIBRARY64_PATH" , execdir); // irix
  u_setenv ("DYLD_LIBRARY_PATH" , execdir); // os sucks from apple
#endif
}

static void
execute (void)
{
  char *null = 0;
  u_dynbuf_append (&exe_argv, &null, sizeof (null));
  systemv ((const char *const *)exe_argv.addr);
}

// this argc/argv is without argv [0]
static void
doit (int argc, char *argv[])
{
  int i;

  u_setenv ("URLADER_CURRDIR", currdir);

  u_set_datadir ();
  u_mkdir (datadir);

  if (!pack_map ())
    u_fatal ("unable to map pack file - executable corrupted?");

  load ();

  while (argc--)
    {
      add_arg (*argv, strlen (*argv) + 1);
      ++argv;
    }

  execute ();
}

#ifdef _WIN32

int APIENTRY
WinMain (HINSTANCE hI, HINSTANCE hP, LPSTR argv, int command_show)
{
  if (!GetModuleFileName (hI, tmppath, sizeof (tmppath)))
    u_fatal ("unable to find executable pack");

  u_setenv ("URLADER_EXEPATH", tmppath);

  pack_handle = u_open (tmppath);
  if (!u_valid (pack_handle))
    u_fatal ("unable to open executable pack");

  if (!GetCurrentDirectory (sizeof (currdir), currdir))
    strcpy (currdir, ".");

  doit (1, &argv);

  return 0;
}

#else

int
main (int argc, char *argv[])
{
  if (!getcwd (currdir, sizeof (currdir)))
    strcpy (currdir, ".");

  {
    const char *exe_path = 0;

    if (strchr (argv [0], '/'))
      exe_path = argv [0];
    else
      {
        const char *p, *path = getenv ("PATH");

        if (!path)
          u_fatal ("unable to find executable, try running with full path.");

        for (p = path; ; )
          {
            const char *e = p;
            int l;

            while (*e && *e != ':')
              ++e;

            l = e - p;
            memcpy (tmppath, p, l);

            if (!l)
              tmppath [l++] = '.';

            tmppath [l++] = '/';

            strcpy (tmppath + l, argv [0]);

            if (!access (tmppath, X_OK))
              break;

            p = e;
            if (!*p)
              u_fatal ("unable to find executable, try running with full path.");

            ++p;
          }

        exe_path = tmppath;
      }

    pack_handle = u_open (exe_path);
    if (!u_valid (pack_handle))
      u_fatal ("unable to open executable for reading - permissions problem?");

    u_setenv ("URLADER_EXEPATH", exe_path);
  }

#if 0
  /* intersperse hostname, for whatever reason */

  if (gethostname (tmppath, sizeof (tmppath)))
    strcpy (tmppath, "default");

  u_append (datadir, tmppath);
#endif

  doit (argc - 1, argv + 1);

  return 0;
}

#endif

Revision:	1.15
Committed:	Mon Jun 10 06:46:32 2013 UTC (10 years, 10 months ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.14:	+4 -4 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	#include "urlib.c"
39
40	#include <stdio.h>
41	#include <stdlib.h>
42	#include <unistd.h>
43	#include <errno.h>
44	#include <string.h>
45	#include <time.h>
46
47	#include "liblzf/lzf_d.c"
48
49	/* some simple? dynamic memory management for paths might save ltos of ram */
50	static u_handle pack_handle;
51	static u_handle lock_handle;
52	static char tmppath[MAX_PATH];
53
54	static int exe_argc;
55	static u_dynbuf exe_argv;
56	static u_dynbuf exe_args; /* actual arguments strings copied here */
57
58	static void
59	tmpdir (const char *dir)
60	{
61	static int cnt;
62
63	for (;;)
64	{
65	// #ifdef _WIN32
66	// sprintf (tmppath, "%s/%x_%x.tmp", dir, (unsigned int)GetCurrentProcessId (), ++cnt);
67	// #else
68	sprintf (tmppath, "%s/t-%x_%x.tmp", dir, (unsigned int)getpid () , ++cnt);
69	// #endif
70
71	if (!u_mkdir (tmppath))
72	return;
73	}
74	}
75
76	static void
77	systemv (const char *const argv[])
78	{
79	#ifdef _WIN32
80	_spawnv (P_WAIT, argv [0], argv);
81	#else
82	pid_t pid = fork ();
83
84	if (pid < 0)
85	u_fatal ("fork failure");
86
87	if (!pid)
88	{
89	execv (argv [0], (void *)argv);
90	_exit (124);
91	}
92
93	int status;
94	waitpid (pid, &status, 0);
95	#endif
96	}
97
98	static void
99	deltree (const char *path)
100	{
101	#ifdef _WIN32
102	char buf[MAX_PATH * 2 + 64];
103	const char *argv[] = { getenv ("COMSPEC"), "/c", "rd", "/s", "/q", buf, 0 };
104	sprintf (buf, "\"%s\"", path);
105	#else
106	const char *argv[] = { "/bin/rm", "-rf", path, 0 };
107	#endif
108	systemv (argv);
109	}
110
111	static char pack_base, pack_end;
112	static struct u_pack_tail *pack_tail;
113	static struct u_pack_hdr *pack_cur;
114	static char *scratch;
115	static unsigned int scratch_size;
116
117	#define PACK_NAME ((char *)(pack_cur + 1))
118	#define PACK_DATA (PACK_NAME + u_16 (pack_cur->namelen) + 1)
119	#define PACK_VALID pack_cur->type
120
121	static void
122	pack_next (void)
123	{
124	unsigned int d = u_32 (pack_cur->datalen);
125
126	pack_cur = (struct u_pack_hdr *)(PACK_DATA + d);
127	}
128
129	static void
130	pack_unmap (void)
131	{
132	if (pack_base)
133	{
134	u_munmap (pack_base, pack_end - pack_base);
135	pack_base = 0;
136	}
137
138	if (scratch)
139	{
140	u_free (scratch, scratch_size);
141	scratch = 0;
142	}
143	}
144
145	static int
146	pack_map (void)
147	{
148	char *addr;
149	unsigned int size;
150
151	#ifdef _WIN32
152	BY_HANDLE_FILE_INFORMATION fi;
153
154	if (!GetFileInformationByHandle (pack_handle, &fi))
155	return 0;
156
157	size = fi.nFileSizeLow;
158	#else
159	size = lseek (pack_handle, 0, SEEK_END);
160	#endif
161
162	addr = u_mmap (pack_handle, size);
163	if (!addr)
164	return 0;
165
166	/pack_unmap ();/
167
168	pack_base = addr;
169	pack_end = pack_base + size;
170
171	pack_tail = (void )(pack_end - sizeof (pack_tail));
172
173	if (memcmp (pack_tail->magic, TAIL_MAGIC, sizeof (TAIL_MAGIC) - 1))
174	return 0;
175
176	pack_cur = (struct u_pack_hdr *)(pack_end - u_32 (pack_tail->size));
177
178	if (pack_cur->type != T_META)
179	return 0;
180
181	scratch = u_malloc (scratch_size = u_32 (pack_tail->max_uncompressed));
182	if (!scratch)
183	return 0;
184
185	return 1;
186	}
187
188	static void
189	add_arg (char *arg, unsigned int len)
190	{
191	char *addr = u_dynbuf_append (&exe_args, arg, len);
192	u_dynbuf_append (&exe_argv, &addr, sizeof (addr));
193	}
194
195	static void
196	load (void)
197	{
198	strcpy (exe_id , PACK_NAME);
199	strcpy (exe_ver, PACK_DATA);
200	u_set_exe_info ();
201
202	if (u_chdir (exe_dir))
203	u_fatal ("unable to change to application data directory");
204
205	u_handle h = u_open ("override");
206	if (u_valid (h))
207	{
208	u_handle oh = pack_handle;
209
210	pack_unmap ();
211	pack_handle = h;
212
213	if (pack_map ()
214	&& strcmp (exe_id , PACK_NAME) == 0
215	&& strcmp (exe_ver, PACK_DATA) <= 0)
216	u_setenv ("URLADER_OVERRIDE", "override");
217	else
218	{
219	pack_unmap ();
220	pack_handle = oh;
221	oh = h;
222	pack_map ();
223	}
224
225	u_close (oh);
226	}
227
228	strcpy (exe_ver, PACK_DATA);
229	u_set_exe_info ();
230	pack_next ();
231
232	for (;;)
233	{
234	if (pack_cur->type == T_ENV)
235	u_setenv (PACK_NAME, PACK_DATA);
236	else if (pack_cur->type == T_ARG)
237	add_arg (PACK_NAME, u_16 (pack_cur->namelen) + 1);
238	else
239	break;
240
241	pack_next ();
242	}
243
244	done_env_arg:
245
246	strcat (strcpy (tmppath, execdir), ".lck");
247	lock_handle = u_lock (tmppath, 0, 1);
248	if (!lock_handle)
249	u_fatal ("unable to lock application instance");
250
251	if (access (execdir, F_OK))
252	{
253	// does not exist yet, so unpack and move
254	tmpdir (exe_dir);
255
256	if (u_chdir (tmppath))
257	u_fatal ("unable to change to new instance directory");
258
259	for (;;)
260	{
261	switch (pack_cur->type)
262	{
263	case T_DIR:
264	u_mkdir (PACK_NAME);
265	break;
266
267	case T_FILE:
268	{
269	u_handle h = u_creat (PACK_NAME, pack_cur->flags & F_EXEC);
270	unsigned int dlen, len = u_32 (pack_cur->datalen);
271	char *data = PACK_DATA;
272
273	if (pack_cur->flags & F_LZF)
274	if (dlen = lzf_decompress (data, len, scratch, scratch_size))
275	{
276	data = scratch;
277	len = dlen;
278	}
279	else
280	u_fatal ("unable to uncompress file data - pack corrupted?");
281
282	if (!u_valid (h))
283	u_fatal ("unable to unpack file from packfile - disk full?");
284
285	if (u_write (h, data, len) != len)
286	u_fatal ("unable to unpack file from packfile - disk full?");
287
288	u_fsync (h);
289	u_close (h);
290	}
291	break;
292
293	case T_NULL:
294	goto done;
295	}
296
297	pack_next ();
298	}
299
300	done:
301	if (u_chdir (datadir))
302	u_fatal ("unable to change to data directory");
303
304	u_sync ();
305
306	if (u_rename (tmppath, execdir))
307	deltree (tmppath); // if move fails, delete new, assume other process created it independently
308	}
309
310	pack_unmap ();
311	u_close (pack_handle);
312
313	if (u_chdir (execdir))
314	u_fatal ("unable to change to application instance directory");
315
316	u_setenv ("URLADER_VERSION", URLADER_VERSION);
317
318	#if 0
319	// yes, this is overkill
320	u_setenv ("SHLIB_PATH" , execdir); // hpux
321	u_setenv ("LIBPATH" , execdir); // aix
322	u_setenv ("LD_LIBRARY_PATH" , execdir); // most elf systems
323	u_setenv ("LD_LIBRARY_PATH_32", execdir); // solaris
324	u_setenv ("LD_LIBRARY_PATH_64", execdir); // solaris
325	u_setenv ("LD_LIBRARYN32_PATH", execdir); // irix
326	u_setenv ("LD_LIBRARY64_PATH" , execdir); // irix
327	u_setenv ("DYLD_LIBRARY_PATH" , execdir); // os sucks from apple
328	#endif
329	}
330
331	static void
332	execute (void)
333	{
334	char *null = 0;
335	u_dynbuf_append (&exe_argv, &null, sizeof (null));
336	systemv ((const char const )exe_argv.addr);
337	}
338
339	// this argc/argv is without argv [0]
340	static void
341	doit (int argc, char *argv[])
342	{
343	int i;
344
345	u_setenv ("URLADER_CURRDIR", currdir);
346
347	u_set_datadir ();
348	u_mkdir (datadir);
349
350	if (!pack_map ())
351	u_fatal ("unable to map pack file - executable corrupted?");
352
353	load ();
354
355	while (argc--)
356	{
357	add_arg (argv, strlen (argv) + 1);
358	++argv;
359	}
360
361	execute ();
362	}
363
364	#ifdef _WIN32
365
366	int APIENTRY
367	WinMain (HINSTANCE hI, HINSTANCE hP, LPSTR argv, int command_show)
368	{
369	if (!GetModuleFileName (hI, tmppath, sizeof (tmppath)))
370	u_fatal ("unable to find executable pack");
371
372	u_setenv ("URLADER_EXEPATH", tmppath);
373
374	pack_handle = u_open (tmppath);
375	if (!u_valid (pack_handle))
376	u_fatal ("unable to open executable pack");
377
378	if (!GetCurrentDirectory (sizeof (currdir), currdir))
379	strcpy (currdir, ".");
380
381	doit (1, &argv);
382
383	return 0;
384	}
385
386	#else
387
388	int
389	main (int argc, char *argv[])
390	{
391	if (!getcwd (currdir, sizeof (currdir)))
392	strcpy (currdir, ".");
393
394	{
395	const char *exe_path = 0;
396
397	if (strchr (argv [0], '/'))
398	exe_path = argv [0];
399	else
400	{
401	const char p, path = getenv ("PATH");
402
403	if (!path)
404	u_fatal ("unable to find executable, try running with full path.");
405
406	for (p = path; ; )
407	{
408	const char *e = p;
409	int l;
410
411	while (e && e != ':')
412	++e;
413
414	l = e - p;
415	memcpy (tmppath, p, l);
416
417	if (!l)
418	tmppath [l++] = '.';
419
420	tmppath [l++] = '/';
421
422	strcpy (tmppath + l, argv [0]);
423
424	if (!access (tmppath, X_OK))
425	break;
426
427	p = e;
428	if (!*p)
429	u_fatal ("unable to find executable, try running with full path.");
430
431	++p;
432	}
433
434	exe_path = tmppath;
435	}
436
437	pack_handle = u_open (exe_path);
438	if (!u_valid (pack_handle))
439	u_fatal ("unable to open executable for reading - permissions problem?");
440
441	u_setenv ("URLADER_EXEPATH", exe_path);
442	}
443
444	#if 0
445	/* intersperse hostname, for whatever reason */
446
447	if (gethostname (tmppath, sizeof (tmppath)))
448	strcpy (tmppath, "default");
449
450	u_append (datadir, tmppath);
451	#endif
452
453	doit (argc - 1, argv + 1);
454
455	return 0;
456	}
457
458	#endif
459