1 /* Return the initial module search path. */
2
3 #include "Python.h"
4 #include "osdefs.h"
5
6 #include <sys/types.h>
7 #include <string.h>
8
9 #ifdef __APPLE__
10 #include <mach-o/dyld.h>
11 #endif
12
13 /* Search in some common locations for the associated Python libraries.
14 *
15 * Two directories must be found, the platform independent directory
16 * (prefix), containing the common .py and .pyc files, and the platform
17 * dependent directory (exec_prefix), containing the shared library
18 * modules. Note that prefix and exec_prefix can be the same directory,
19 * but for some installations, they are different.
20 *
21 * Py_GetPath() carries out separate searches for prefix and exec_prefix.
22 * Each search tries a number of different locations until a ``landmark''
23 * file or directory is found. If no prefix or exec_prefix is found, a
24 * warning message is issued and the preprocessor defined PREFIX and
25 * EXEC_PREFIX are used (even though they will not work); python carries on
26 * as best as is possible, but most imports will fail.
27 *
28 * Before any searches are done, the location of the executable is
29 * determined. If argv[0] has one or more slashes in it, it is used
30 * unchanged. Otherwise, it must have been invoked from the shell's path,
31 * so we search $PATH for the named executable and use that. If the
32 * executable was not found on $PATH (or there was no $PATH environment
33 * variable), the original argv[0] string is used.
34 *
35 * Next, the executable location is examined to see if it is a symbolic
36 * link. If so, the link is chased (correctly interpreting a relative
37 * pathname if one is found) and the directory of the link target is used.
38 *
39 * Finally, argv0_path is set to the directory containing the executable
40 * (i.e. the last component is stripped).
41 *
42 * With argv0_path in hand, we perform a number of steps. The same steps
43 * are performed for prefix and for exec_prefix, but with a different
44 * landmark.
45 *
46 * Step 1. Are we running python out of the build directory? This is
47 * checked by looking for a different kind of landmark relative to
48 * argv0_path. For prefix, the landmark's path is derived from the VPATH
49 * preprocessor variable (taking into account that its value is almost, but
50 * not quite, what we need). For exec_prefix, the landmark is
51 * Modules/Setup. If the landmark is found, we're done.
52 *
53 * For the remaining steps, the prefix landmark will always be
54 * lib/python$VERSION/os.py and the exec_prefix will always be
55 * lib/python$VERSION/lib-dynload, where $VERSION is Python's version
56 * number as supplied by the Makefile. Note that this means that no more
57 * build directory checking is performed; if the first step did not find
58 * the landmarks, the assumption is that python is running from an
59 * installed setup.
60 *
61 * Step 2. See if the $PYTHONHOME environment variable points to the
62 * installed location of the Python libraries. If $PYTHONHOME is set, then
63 * it points to prefix and exec_prefix. $PYTHONHOME can be a single
64 * directory, which is used for both, or the prefix and exec_prefix
65 * directories separated by a colon.
66 *
67 * Step 3. Try to find prefix and exec_prefix relative to argv0_path,
68 * backtracking up the path until it is exhausted. This is the most common
69 * step to succeed. Note that if prefix and exec_prefix are different,
70 * exec_prefix is more likely to be found; however if exec_prefix is a
71 * subdirectory of prefix, both will be found.
72 *
73 * Step 4. Search the directories pointed to by the preprocessor variables
74 * PREFIX and EXEC_PREFIX. These are supplied by the Makefile but can be
75 * passed in as options to the configure script.
76 *
77 * That's it!
78 *
79 * Well, almost. Once we have determined prefix and exec_prefix, the
80 * preprocessor variable PYTHONPATH is used to construct a path. Each
81 * relative path on PYTHONPATH is prefixed with prefix. Then the directory
82 * containing the shared library modules is appended. The environment
83 * variable $PYTHONPATH is inserted in front of it all. Finally, the
84 * prefix and exec_prefix globals are tweaked so they reflect the values
85 * expected by other code, by stripping the "lib/python$VERSION/..." stuff
86 * off. If either points to the build directory, the globals are reset to
87 * the corresponding preprocessor variables (so sys.prefix will reflect the
88 * installation location, even though sys.path points into the build
89 * directory). This seems to make more sense given that currently the only
90 * known use of sys.prefix and sys.exec_prefix is for the ILU installation
91 * process to find the installed Python tree.
92 */
93
94 #ifdef __cplusplus
95 extern "C" {
96 #endif
97
98
99 #if !defined(PREFIX) || !defined(EXEC_PREFIX) || !defined(VERSION) || !defined(VPATH)
100 #error "PREFIX, EXEC_PREFIX, VERSION, and VPATH must be constant defined"
101 #endif
102
103 #ifndef LANDMARK
104 #define LANDMARK "os.py"
105 #endif
106
107 static char prefix[MAXPATHLEN+1];
108 static char exec_prefix[MAXPATHLEN+1];
109 static char progpath[MAXPATHLEN+1];
110 static char *module_search_path = NULL;
111 static char lib_python[] = "lib/python" VERSION;
112
113 static void
reduce(char * dir)114 reduce(char *dir)
115 {
116 size_t i = strlen(dir);
117 while (i > 0 && dir[i] != SEP)
118 --i;
119 dir[i] = '\0';
120 }
121
122
123 static int
isfile(char * filename)124 isfile(char *filename) /* Is file, not directory */
125 {
126 struct stat buf;
127 if (stat(filename, &buf) != 0)
128 return 0;
129 if (!S_ISREG(buf.st_mode))
130 return 0;
131 return 1;
132 }
133
134
135 static int
ismodule(char * filename)136 ismodule(char *filename) /* Is module -- check for .pyc/.pyo too */
137 {
138 if (isfile(filename))
139 return 1;
140
141 /* Check for the compiled version of prefix. */
142 if (strlen(filename) < MAXPATHLEN) {
143 strcat(filename, Py_OptimizeFlag ? "o" : "c");
144 if (isfile(filename))
145 return 1;
146 }
147 return 0;
148 }
149
150
151 static int
isxfile(char * filename)152 isxfile(char *filename) /* Is executable file */
153 {
154 struct stat buf;
155 if (stat(filename, &buf) != 0)
156 return 0;
157 if (!S_ISREG(buf.st_mode))
158 return 0;
159 if ((buf.st_mode & 0111) == 0)
160 return 0;
161 return 1;
162 }
163
164
165 static int
isdir(char * filename)166 isdir(char *filename) /* Is directory */
167 {
168 struct stat buf;
169 if (stat(filename, &buf) != 0)
170 return 0;
171 if (!S_ISDIR(buf.st_mode))
172 return 0;
173 return 1;
174 }
175
176
177 /* Add a path component, by appending stuff to buffer.
178 buffer must have at least MAXPATHLEN + 1 bytes allocated, and contain a
179 NUL-terminated string with no more than MAXPATHLEN characters (not counting
180 the trailing NUL). It's a fatal error if it contains a string longer than
181 that (callers must be careful!). If these requirements are met, it's
182 guaranteed that buffer will still be a NUL-terminated string with no more
183 than MAXPATHLEN characters at exit. If stuff is too long, only as much of
184 stuff as fits will be appended.
185 */
186 static void
joinpath(char * buffer,char * stuff)187 joinpath(char *buffer, char *stuff)
188 {
189 size_t n, k;
190 if (stuff[0] == SEP)
191 n = 0;
192 else {
193 n = strlen(buffer);
194 if (n > 0 && buffer[n-1] != SEP && n < MAXPATHLEN)
195 buffer[n++] = SEP;
196 }
197 if (n > MAXPATHLEN)
198 Py_FatalError("buffer overflow in getpath.c's joinpath()");
199 k = strlen(stuff);
200 if (n + k > MAXPATHLEN)
201 k = MAXPATHLEN - n;
202 strncpy(buffer+n, stuff, k);
203 buffer[n+k] = '\0';
204 }
205
206 /* copy_absolute requires that path be allocated at least
207 MAXPATHLEN + 1 bytes and that p be no more than MAXPATHLEN bytes. */
208 static void
copy_absolute(char * path,char * p)209 copy_absolute(char *path, char *p)
210 {
211 if (p[0] == SEP)
212 strcpy(path, p);
213 else {
214 if (!getcwd(path, MAXPATHLEN)) {
215 /* unable to get the current directory */
216 strcpy(path, p);
217 return;
218 }
219 if (p[0] == '.' && p[1] == SEP)
220 p += 2;
221 joinpath(path, p);
222 }
223 }
224
225 /* absolutize() requires that path be allocated at least MAXPATHLEN+1 bytes. */
226 static void
absolutize(char * path)227 absolutize(char *path)
228 {
229 char buffer[MAXPATHLEN + 1];
230
231 if (path[0] == SEP)
232 return;
233 copy_absolute(buffer, path);
234 strcpy(path, buffer);
235 }
236
237 /* search_for_prefix requires that argv0_path be no more than MAXPATHLEN
238 bytes long.
239 */
240 static int
search_for_prefix(char * argv0_path,char * home)241 search_for_prefix(char *argv0_path, char *home)
242 {
243 size_t n;
244 char *vpath;
245
246 /* If PYTHONHOME is set, we believe it unconditionally */
247 if (home) {
248 char *delim;
249 strncpy(prefix, home, MAXPATHLEN);
250 delim = strchr(prefix, DELIM);
251 if (delim)
252 *delim = '\0';
253 joinpath(prefix, lib_python);
254 joinpath(prefix, LANDMARK);
255 return 1;
256 }
257
258 /* Check to see if argv[0] is in the build directory */
259 strcpy(prefix, argv0_path);
260 joinpath(prefix, "Modules/Setup");
261 if (isfile(prefix)) {
262 /* Check VPATH to see if argv0_path is in the build directory. */
263 vpath = VPATH;
264 strcpy(prefix, argv0_path);
265 joinpath(prefix, vpath);
266 joinpath(prefix, "Lib");
267 joinpath(prefix, LANDMARK);
268 if (ismodule(prefix))
269 return -1;
270 }
271
272 /* Search from argv0_path, until root is found */
273 copy_absolute(prefix, argv0_path);
274 do {
275 n = strlen(prefix);
276 joinpath(prefix, lib_python);
277 joinpath(prefix, LANDMARK);
278 if (ismodule(prefix))
279 return 1;
280 prefix[n] = '\0';
281 reduce(prefix);
282 } while (prefix[0]);
283
284 /* Look at configure's PREFIX */
285 strncpy(prefix, PREFIX, MAXPATHLEN);
286 joinpath(prefix, lib_python);
287 joinpath(prefix, LANDMARK);
288 if (ismodule(prefix))
289 return 1;
290
291 /* Fail */
292 return 0;
293 }
294
295
296 /* search_for_exec_prefix requires that argv0_path be no more than
297 MAXPATHLEN bytes long.
298 */
299 static int
search_for_exec_prefix(char * argv0_path,char * home)300 search_for_exec_prefix(char *argv0_path, char *home)
301 {
302 size_t n;
303
304 /* If PYTHONHOME is set, we believe it unconditionally */
305 if (home) {
306 char *delim;
307 delim = strchr(home, DELIM);
308 if (delim)
309 strncpy(exec_prefix, delim+1, MAXPATHLEN);
310 else
311 strncpy(exec_prefix, home, MAXPATHLEN);
312 joinpath(exec_prefix, lib_python);
313 joinpath(exec_prefix, "lib-dynload");
314 return 1;
315 }
316
317 /* Check to see if argv[0] is in the build directory. "pybuilddir.txt"
318 is written by setup.py and contains the relative path to the location
319 of shared library modules. */
320 strcpy(exec_prefix, argv0_path);
321 joinpath(exec_prefix, "pybuilddir.txt");
322 if (isfile(exec_prefix)) {
323 FILE *f = fopen(exec_prefix, "r");
324 if (f == NULL)
325 errno = 0;
326 else {
327 char rel_builddir_path[MAXPATHLEN+1];
328 size_t n;
329 n = fread(rel_builddir_path, 1, MAXPATHLEN, f);
330 rel_builddir_path[n] = '\0';
331 fclose(f);
332 strcpy(exec_prefix, argv0_path);
333 joinpath(exec_prefix, rel_builddir_path);
334 return -1;
335 }
336 }
337
338 /* Search from argv0_path, until root is found */
339 copy_absolute(exec_prefix, argv0_path);
340 do {
341 n = strlen(exec_prefix);
342 joinpath(exec_prefix, lib_python);
343 joinpath(exec_prefix, "lib-dynload");
344 if (isdir(exec_prefix))
345 return 1;
346 exec_prefix[n] = '\0';
347 reduce(exec_prefix);
348 } while (exec_prefix[0]);
349
350 /* Look at configure's EXEC_PREFIX */
351 strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
352 joinpath(exec_prefix, lib_python);
353 joinpath(exec_prefix, "lib-dynload");
354 if (isdir(exec_prefix))
355 return 1;
356
357 /* Fail */
358 return 0;
359 }
360
361
362 static void
calculate_path(void)363 calculate_path(void)
364 {
365 extern char *Py_GetProgramName(void);
366
367 static char delimiter[2] = {DELIM, '\0'};
368 static char separator[2] = {SEP, '\0'};
369 char *pythonpath = PYTHONPATH;
370 char *rtpypath = Py_GETENV("PYTHONPATH");
371 char *home = Py_GetPythonHome();
372 char *path = getenv("PATH");
373 char *prog = Py_GetProgramName();
374 char argv0_path[MAXPATHLEN+1];
375 char zip_path[MAXPATHLEN+1];
376 int pfound, efound; /* 1 if found; -1 if found build directory */
377 char *buf;
378 size_t bufsz;
379 size_t prefixsz;
380 char *defpath = pythonpath;
381 #ifdef WITH_NEXT_FRAMEWORK
382 NSModule pythonModule;
383 #endif
384 #ifdef __APPLE__
385 #if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_4
386 uint32_t nsexeclength = MAXPATHLEN;
387 #else
388 unsigned long nsexeclength = MAXPATHLEN;
389 #endif
390 #endif
391
392 /* If there is no slash in the argv0 path, then we have to
393 * assume python is on the user's $PATH, since there's no
394 * other way to find a directory to start the search from. If
395 * $PATH isn't exported, you lose.
396 */
397 if (strchr(prog, SEP))
398 strncpy(progpath, prog, MAXPATHLEN);
399 #ifdef __APPLE__
400 /* On Mac OS X, if a script uses an interpreter of the form
401 * "#!/opt/python2.3/bin/python", the kernel only passes "python"
402 * as argv[0], which falls through to the $PATH search below.
403 * If /opt/python2.3/bin isn't in your path, or is near the end,
404 * this algorithm may incorrectly find /usr/bin/python. To work
405 * around this, we can use _NSGetExecutablePath to get a better
406 * hint of what the intended interpreter was, although this
407 * will fail if a relative path was used. but in that case,
408 * absolutize() should help us out below
409 */
410 else if(0 == _NSGetExecutablePath(progpath, &nsexeclength) && progpath[0] == SEP)
411 ;
412 #endif /* __APPLE__ */
413 else if (path) {
414 while (1) {
415 char *delim = strchr(path, DELIM);
416
417 if (delim) {
418 size_t len = delim - path;
419 if (len > MAXPATHLEN)
420 len = MAXPATHLEN;
421 strncpy(progpath, path, len);
422 *(progpath + len) = '\0';
423 }
424 else
425 strncpy(progpath, path, MAXPATHLEN);
426
427 joinpath(progpath, prog);
428 if (isxfile(progpath))
429 break;
430
431 if (!delim) {
432 progpath[0] = '\0';
433 break;
434 }
435 path = delim + 1;
436 }
437 }
438 else
439 progpath[0] = '\0';
440 if (progpath[0] != SEP && progpath[0] != '\0')
441 absolutize(progpath);
442 strncpy(argv0_path, progpath, MAXPATHLEN);
443 argv0_path[MAXPATHLEN] = '\0';
444
445 #ifdef WITH_NEXT_FRAMEWORK
446 /* On Mac OS X we have a special case if we're running from a framework.
447 ** This is because the python home should be set relative to the library,
448 ** which is in the framework, not relative to the executable, which may
449 ** be outside of the framework. Except when we're in the build directory...
450 */
451 pythonModule = NSModuleForSymbol(NSLookupAndBindSymbol("_Py_Initialize"));
452 /* Use dylib functions to find out where the framework was loaded from */
453 buf = (char *)NSLibraryNameForModule(pythonModule);
454 if (buf != NULL) {
455 /* We're in a framework. */
456 /* See if we might be in the build directory. The framework in the
457 ** build directory is incomplete, it only has the .dylib and a few
458 ** needed symlinks, it doesn't have the Lib directories and such.
459 ** If we're running with the framework from the build directory we must
460 ** be running the interpreter in the build directory, so we use the
461 ** build-directory-specific logic to find Lib and such.
462 */
463 strncpy(argv0_path, buf, MAXPATHLEN);
464 reduce(argv0_path);
465 joinpath(argv0_path, lib_python);
466 joinpath(argv0_path, LANDMARK);
467 if (!ismodule(argv0_path)) {
468 /* We are in the build directory so use the name of the
469 executable - we know that the absolute path is passed */
470 strncpy(argv0_path, progpath, MAXPATHLEN);
471 }
472 else {
473 /* Use the location of the library as the progpath */
474 strncpy(argv0_path, buf, MAXPATHLEN);
475 }
476 }
477 #endif
478
479 #if HAVE_READLINK
480 {
481 char tmpbuffer[MAXPATHLEN+1];
482 int linklen = readlink(progpath, tmpbuffer, MAXPATHLEN);
483 while (linklen != -1) {
484 /* It's not null terminated! */
485 tmpbuffer[linklen] = '\0';
486 if (tmpbuffer[0] == SEP)
487 /* tmpbuffer should never be longer than MAXPATHLEN,
488 but extra check does not hurt */
489 strncpy(argv0_path, tmpbuffer, MAXPATHLEN);
490 else {
491 /* Interpret relative to progpath */
492 reduce(argv0_path);
493 joinpath(argv0_path, tmpbuffer);
494 }
495 linklen = readlink(argv0_path, tmpbuffer, MAXPATHLEN);
496 }
497 }
498 #endif /* HAVE_READLINK */
499
500 reduce(argv0_path);
501 /* At this point, argv0_path is guaranteed to be less than
502 MAXPATHLEN bytes long.
503 */
504
505 if (!(pfound = search_for_prefix(argv0_path, home))) {
506 if (!Py_FrozenFlag)
507 fprintf(stderr,
508 "Could not find platform independent libraries <prefix>\n");
509 strncpy(prefix, PREFIX, MAXPATHLEN);
510 joinpath(prefix, lib_python);
511 }
512 else
513 reduce(prefix);
514
515 strncpy(zip_path, prefix, MAXPATHLEN);
516 zip_path[MAXPATHLEN] = '\0';
517 if (pfound > 0) { /* Use the reduced prefix returned by Py_GetPrefix() */
518 reduce(zip_path);
519 reduce(zip_path);
520 }
521 else
522 strncpy(zip_path, PREFIX, MAXPATHLEN);
523 joinpath(zip_path, "lib/python00.zip");
524 bufsz = strlen(zip_path); /* Replace "00" with version */
525 zip_path[bufsz - 6] = VERSION[0];
526 zip_path[bufsz - 5] = VERSION[2];
527
528 if (!(efound = search_for_exec_prefix(argv0_path, home))) {
529 if (!Py_FrozenFlag)
530 fprintf(stderr,
531 "Could not find platform dependent libraries <exec_prefix>\n");
532 strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
533 joinpath(exec_prefix, "lib/lib-dynload");
534 }
535 /* If we found EXEC_PREFIX do *not* reduce it! (Yet.) */
536
537 if ((!pfound || !efound) && !Py_FrozenFlag)
538 fprintf(stderr,
539 "Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]\n");
540
541 /* Calculate size of return buffer.
542 */
543 bufsz = 0;
544
545 if (rtpypath)
546 bufsz += strlen(rtpypath) + 1;
547
548 prefixsz = strlen(prefix) + 1;
549
550 while (1) {
551 char *delim = strchr(defpath, DELIM);
552
553 if (defpath[0] != SEP)
554 /* Paths are relative to prefix */
555 bufsz += prefixsz;
556
557 if (delim)
558 bufsz += delim - defpath + 1;
559 else {
560 bufsz += strlen(defpath) + 1;
561 break;
562 }
563 defpath = delim + 1;
564 }
565
566 bufsz += strlen(zip_path) + 1;
567 bufsz += strlen(exec_prefix) + 1;
568
569 /* This is the only malloc call in this file */
570 buf = (char *)PyMem_Malloc(bufsz);
571
572 if (buf == NULL) {
573 /* We can't exit, so print a warning and limp along */
574 fprintf(stderr, "Not enough memory for dynamic PYTHONPATH.\n");
575 fprintf(stderr, "Using default static PYTHONPATH.\n");
576 module_search_path = PYTHONPATH;
577 }
578 else {
579 /* Run-time value of $PYTHONPATH goes first */
580 if (rtpypath) {
581 strcpy(buf, rtpypath);
582 strcat(buf, delimiter);
583 }
584 else
585 buf[0] = '\0';
586
587 /* Next is the default zip path */
588 strcat(buf, zip_path);
589 strcat(buf, delimiter);
590
591 /* Next goes merge of compile-time $PYTHONPATH with
592 * dynamically located prefix.
593 */
594 defpath = pythonpath;
595 while (1) {
596 char *delim = strchr(defpath, DELIM);
597
598 if (defpath[0] != SEP) {
599 strcat(buf, prefix);
600 if (prefixsz >= 2 && prefix[prefixsz - 2] != SEP &&
601 defpath[0] != (delim ? DELIM : L'\0')) { /* not empty */
602 strcat(buf, separator);
603 }
604 }
605
606 if (delim) {
607 size_t len = delim - defpath + 1;
608 size_t end = strlen(buf) + len;
609 strncat(buf, defpath, len);
610 *(buf + end) = '\0';
611 }
612 else {
613 strcat(buf, defpath);
614 break;
615 }
616 defpath = delim + 1;
617 }
618 strcat(buf, delimiter);
619
620 /* Finally, on goes the directory for dynamic-load modules */
621 strcat(buf, exec_prefix);
622
623 /* And publish the results */
624 module_search_path = buf;
625 }
626
627 /* Reduce prefix and exec_prefix to their essence,
628 * e.g. /usr/local/lib/python1.5 is reduced to /usr/local.
629 * If we're loading relative to the build directory,
630 * return the compiled-in defaults instead.
631 */
632 if (pfound > 0) {
633 reduce(prefix);
634 reduce(prefix);
635 /* The prefix is the root directory, but reduce() chopped
636 * off the "/". */
637 if (!prefix[0])
638 strcpy(prefix, separator);
639 }
640 else
641 strncpy(prefix, PREFIX, MAXPATHLEN);
642
643 if (efound > 0) {
644 reduce(exec_prefix);
645 reduce(exec_prefix);
646 reduce(exec_prefix);
647 if (!exec_prefix[0])
648 strcpy(exec_prefix, separator);
649 }
650 else
651 strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
652 }
653
654
655 /* External interface */
656
657 char *
Py_GetPath(void)658 Py_GetPath(void)
659 {
660 if (!module_search_path)
661 calculate_path();
662 return module_search_path;
663 }
664
665 char *
Py_GetPrefix(void)666 Py_GetPrefix(void)
667 {
668 if (!module_search_path)
669 calculate_path();
670 return prefix;
671 }
672
673 char *
Py_GetExecPrefix(void)674 Py_GetExecPrefix(void)
675 {
676 if (!module_search_path)
677 calculate_path();
678 return exec_prefix;
679 }
680
681 char *
Py_GetProgramFullPath(void)682 Py_GetProgramFullPath(void)
683 {
684 if (!module_search_path)
685 calculate_path();
686 return progpath;
687 }
688
689
690 #ifdef __cplusplus
691 }
692 #endif
693
694