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 #ifndef VERSION
100 #define VERSION "2.1"
101 #endif
102
103 #ifndef VPATH
104 #define VPATH "."
105 #endif
106
107 #ifndef PREFIX
108 # ifdef __VMS
109 # define PREFIX ""
110 # else
111 # define PREFIX "/usr/local"
112 # endif
113 #endif
114
115 #ifndef EXEC_PREFIX
116 #define EXEC_PREFIX PREFIX
117 #endif
118
119 #ifndef PYTHONPATH
120 #define PYTHONPATH PREFIX "/lib/python" VERSION ":" \
121 EXEC_PREFIX "/lib/python" VERSION "/lib-dynload"
122 #endif
123
124 #ifndef LANDMARK
125 #define LANDMARK "os.py"
126 #endif
127
128 static char prefix[MAXPATHLEN+1];
129 static char exec_prefix[MAXPATHLEN+1];
130 static char progpath[MAXPATHLEN+1];
131 static char *module_search_path = NULL;
132 static char lib_python[] = "lib/python" VERSION;
133
134 static void
reduce(char * dir)135 reduce(char *dir)
136 {
137 size_t i = strlen(dir);
138 while (i > 0 && dir[i] != SEP)
139 --i;
140 dir[i] = '\0';
141 }
142
143
144 static int
isfile(char * filename)145 isfile(char *filename) /* Is file, not directory */
146 {
147 struct stat buf;
148 if (stat(filename, &buf) != 0)
149 return 0;
150 if (!S_ISREG(buf.st_mode))
151 return 0;
152 return 1;
153 }
154
155
156 static int
ismodule(char * filename)157 ismodule(char *filename) /* Is module -- check for .pyc/.pyo too */
158 {
159 if (isfile(filename))
160 return 1;
161
162 /* Check for the compiled version of prefix. */
163 if (strlen(filename) < MAXPATHLEN) {
164 strcat(filename, Py_OptimizeFlag ? "o" : "c");
165 if (isfile(filename))
166 return 1;
167 }
168 return 0;
169 }
170
171
172 static int
isxfile(char * filename)173 isxfile(char *filename) /* Is executable file */
174 {
175 struct stat buf;
176 if (stat(filename, &buf) != 0)
177 return 0;
178 if (!S_ISREG(buf.st_mode))
179 return 0;
180 if ((buf.st_mode & 0111) == 0)
181 return 0;
182 return 1;
183 }
184
185
186 static int
isdir(char * filename)187 isdir(char *filename) /* Is directory */
188 {
189 struct stat buf;
190 if (stat(filename, &buf) != 0)
191 return 0;
192 if (!S_ISDIR(buf.st_mode))
193 return 0;
194 return 1;
195 }
196
197
198 /* Add a path component, by appending stuff to buffer.
199 buffer must have at least MAXPATHLEN + 1 bytes allocated, and contain a
200 NUL-terminated string with no more than MAXPATHLEN characters (not counting
201 the trailing NUL). It's a fatal error if it contains a string longer than
202 that (callers must be careful!). If these requirements are met, it's
203 guaranteed that buffer will still be a NUL-terminated string with no more
204 than MAXPATHLEN characters at exit. If stuff is too long, only as much of
205 stuff as fits will be appended.
206 */
207 static void
joinpath(char * buffer,char * stuff)208 joinpath(char *buffer, char *stuff)
209 {
210 size_t n, k;
211 if (stuff[0] == SEP)
212 n = 0;
213 else {
214 n = strlen(buffer);
215 if (n > 0 && buffer[n-1] != SEP && n < MAXPATHLEN)
216 buffer[n++] = SEP;
217 }
218 if (n > MAXPATHLEN)
219 Py_FatalError("buffer overflow in getpath.c's joinpath()");
220 k = strlen(stuff);
221 if (n + k > MAXPATHLEN)
222 k = MAXPATHLEN - n;
223 strncpy(buffer+n, stuff, k);
224 buffer[n+k] = '\0';
225 }
226
227 /* copy_absolute requires that path be allocated at least
228 MAXPATHLEN + 1 bytes and that p be no more than MAXPATHLEN bytes. */
229 static void
copy_absolute(char * path,char * p)230 copy_absolute(char *path, char *p)
231 {
232 if (p[0] == SEP)
233 strcpy(path, p);
234 else {
235 if (!getcwd(path, MAXPATHLEN)) {
236 /* unable to get the current directory */
237 strcpy(path, p);
238 return;
239 }
240 if (p[0] == '.' && p[1] == SEP)
241 p += 2;
242 joinpath(path, p);
243 }
244 }
245
246 /* absolutize() requires that path be allocated at least MAXPATHLEN+1 bytes. */
247 static void
absolutize(char * path)248 absolutize(char *path)
249 {
250 char buffer[MAXPATHLEN + 1];
251
252 if (path[0] == SEP)
253 return;
254 copy_absolute(buffer, path);
255 strcpy(path, buffer);
256 }
257
258 /* search_for_prefix requires that argv0_path be no more than MAXPATHLEN
259 bytes long.
260 */
261 static int
search_for_prefix(char * argv0_path,char * home)262 search_for_prefix(char *argv0_path, char *home)
263 {
264 size_t n;
265 char *vpath;
266
267 /* If PYTHONHOME is set, we believe it unconditionally */
268 if (home) {
269 char *delim;
270 strncpy(prefix, home, MAXPATHLEN);
271 delim = strchr(prefix, DELIM);
272 if (delim)
273 *delim = '\0';
274 joinpath(prefix, lib_python);
275 joinpath(prefix, LANDMARK);
276 return 1;
277 }
278
279 /* Check to see if argv[0] is in the build directory */
280 strcpy(prefix, argv0_path);
281 joinpath(prefix, "Modules/Setup");
282 if (isfile(prefix)) {
283 /* Check VPATH to see if argv0_path is in the build directory. */
284 vpath = VPATH;
285 strcpy(prefix, argv0_path);
286 joinpath(prefix, vpath);
287 joinpath(prefix, "Lib");
288 joinpath(prefix, LANDMARK);
289 if (ismodule(prefix))
290 return -1;
291 }
292
293 /* Search from argv0_path, until root is found */
294 copy_absolute(prefix, argv0_path);
295 do {
296 n = strlen(prefix);
297 joinpath(prefix, lib_python);
298 joinpath(prefix, LANDMARK);
299 if (ismodule(prefix))
300 return 1;
301 prefix[n] = '\0';
302 reduce(prefix);
303 } while (prefix[0]);
304
305 /* Look at configure's PREFIX */
306 strncpy(prefix, PREFIX, MAXPATHLEN);
307 joinpath(prefix, lib_python);
308 joinpath(prefix, LANDMARK);
309 if (ismodule(prefix))
310 return 1;
311
312 /* Fail */
313 return 0;
314 }
315
316
317 /* search_for_exec_prefix requires that argv0_path be no more than
318 MAXPATHLEN bytes long.
319 */
320 static int
search_for_exec_prefix(char * argv0_path,char * home)321 search_for_exec_prefix(char *argv0_path, char *home)
322 {
323 size_t n;
324
325 /* If PYTHONHOME is set, we believe it unconditionally */
326 if (home) {
327 char *delim;
328 delim = strchr(home, DELIM);
329 if (delim)
330 strncpy(exec_prefix, delim+1, MAXPATHLEN);
331 else
332 strncpy(exec_prefix, home, MAXPATHLEN);
333 joinpath(exec_prefix, lib_python);
334 joinpath(exec_prefix, "lib-dynload");
335 return 1;
336 }
337
338 /* Check to see if argv[0] is in the build directory */
339 strcpy(exec_prefix, argv0_path);
340 joinpath(exec_prefix, "Modules/Setup");
341 if (isfile(exec_prefix)) {
342 reduce(exec_prefix);
343 return -1;
344 }
345
346 /* Search from argv0_path, until root is found */
347 copy_absolute(exec_prefix, argv0_path);
348 do {
349 n = strlen(exec_prefix);
350 joinpath(exec_prefix, lib_python);
351 joinpath(exec_prefix, "lib-dynload");
352 if (isdir(exec_prefix))
353 return 1;
354 exec_prefix[n] = '\0';
355 reduce(exec_prefix);
356 } while (exec_prefix[0]);
357
358 /* Look at configure's EXEC_PREFIX */
359 strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
360 joinpath(exec_prefix, lib_python);
361 joinpath(exec_prefix, "lib-dynload");
362 if (isdir(exec_prefix))
363 return 1;
364
365 /* Fail */
366 return 0;
367 }
368
369
370 static void
calculate_path(void)371 calculate_path(void)
372 {
373 extern char *Py_GetProgramName(void);
374
375 static char delimiter[2] = {DELIM, '\0'};
376 static char separator[2] = {SEP, '\0'};
377 char *pythonpath = PYTHONPATH;
378 char *rtpypath = Py_GETENV("PYTHONPATH");
379 char *home = Py_GetPythonHome();
380 char *path = getenv("PATH");
381 char *prog = Py_GetProgramName();
382 char argv0_path[MAXPATHLEN+1];
383 char zip_path[MAXPATHLEN+1];
384 int pfound, efound; /* 1 if found; -1 if found build directory */
385 char *buf;
386 size_t bufsz;
387 size_t prefixsz;
388 char *defpath = pythonpath;
389 #ifdef WITH_NEXT_FRAMEWORK
390 NSModule pythonModule;
391 #endif
392 #ifdef __APPLE__
393 #if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_4
394 uint32_t nsexeclength = MAXPATHLEN;
395 #else
396 unsigned long nsexeclength = MAXPATHLEN;
397 #endif
398 #endif
399
400 /* If there is no slash in the argv0 path, then we have to
401 * assume python is on the user's $PATH, since there's no
402 * other way to find a directory to start the search from. If
403 * $PATH isn't exported, you lose.
404 */
405 if (strchr(prog, SEP))
406 strncpy(progpath, prog, MAXPATHLEN);
407 #ifdef __APPLE__
408 /* On Mac OS X, if a script uses an interpreter of the form
409 * "#!/opt/python2.3/bin/python", the kernel only passes "python"
410 * as argv[0], which falls through to the $PATH search below.
411 * If /opt/python2.3/bin isn't in your path, or is near the end,
412 * this algorithm may incorrectly find /usr/bin/python. To work
413 * around this, we can use _NSGetExecutablePath to get a better
414 * hint of what the intended interpreter was, although this
415 * will fail if a relative path was used. but in that case,
416 * absolutize() should help us out below
417 */
418 else if(0 == _NSGetExecutablePath(progpath, &nsexeclength) && progpath[0] == SEP)
419 ;
420 #endif /* __APPLE__ */
421 else if (path) {
422 while (1) {
423 char *delim = strchr(path, DELIM);
424
425 if (delim) {
426 size_t len = delim - path;
427 if (len > MAXPATHLEN)
428 len = MAXPATHLEN;
429 strncpy(progpath, path, len);
430 *(progpath + len) = '\0';
431 }
432 else
433 strncpy(progpath, path, MAXPATHLEN);
434
435 joinpath(progpath, prog);
436 if (isxfile(progpath))
437 break;
438
439 if (!delim) {
440 progpath[0] = '\0';
441 break;
442 }
443 path = delim + 1;
444 }
445 }
446 else
447 progpath[0] = '\0';
448 if (progpath[0] != SEP && progpath[0] != '\0')
449 absolutize(progpath);
450 strncpy(argv0_path, progpath, MAXPATHLEN);
451 argv0_path[MAXPATHLEN] = '\0';
452
453 #ifdef WITH_NEXT_FRAMEWORK
454 /* On Mac OS X we have a special case if we're running from a framework.
455 ** This is because the python home should be set relative to the library,
456 ** which is in the framework, not relative to the executable, which may
457 ** be outside of the framework. Except when we're in the build directory...
458 */
459 pythonModule = NSModuleForSymbol(NSLookupAndBindSymbol("_Py_Initialize"));
460 /* Use dylib functions to find out where the framework was loaded from */
461 buf = (char *)NSLibraryNameForModule(pythonModule);
462 if (buf != NULL) {
463 /* We're in a framework. */
464 /* See if we might be in the build directory. The framework in the
465 ** build directory is incomplete, it only has the .dylib and a few
466 ** needed symlinks, it doesn't have the Lib directories and such.
467 ** If we're running with the framework from the build directory we must
468 ** be running the interpreter in the build directory, so we use the
469 ** build-directory-specific logic to find Lib and such.
470 */
471 strncpy(argv0_path, buf, MAXPATHLEN);
472 reduce(argv0_path);
473 joinpath(argv0_path, lib_python);
474 joinpath(argv0_path, LANDMARK);
475 if (!ismodule(argv0_path)) {
476 /* We are in the build directory so use the name of the
477 executable - we know that the absolute path is passed */
478 strncpy(argv0_path, progpath, MAXPATHLEN);
479 }
480 else {
481 /* Use the location of the library as the progpath */
482 strncpy(argv0_path, buf, MAXPATHLEN);
483 }
484 }
485 #endif
486
487 #if HAVE_READLINK
488 {
489 char tmpbuffer[MAXPATHLEN+1];
490 int linklen = readlink(progpath, tmpbuffer, MAXPATHLEN);
491 while (linklen != -1) {
492 /* It's not null terminated! */
493 tmpbuffer[linklen] = '\0';
494 if (tmpbuffer[0] == SEP)
495 /* tmpbuffer should never be longer than MAXPATHLEN,
496 but extra check does not hurt */
497 strncpy(argv0_path, tmpbuffer, MAXPATHLEN);
498 else {
499 /* Interpret relative to progpath */
500 reduce(argv0_path);
501 joinpath(argv0_path, tmpbuffer);
502 }
503 linklen = readlink(argv0_path, tmpbuffer, MAXPATHLEN);
504 }
505 }
506 #endif /* HAVE_READLINK */
507
508 reduce(argv0_path);
509 /* At this point, argv0_path is guaranteed to be less than
510 MAXPATHLEN bytes long.
511 */
512
513 if (!(pfound = search_for_prefix(argv0_path, home))) {
514 if (!Py_FrozenFlag)
515 fprintf(stderr,
516 "Could not find platform independent libraries <prefix>\n");
517 strncpy(prefix, PREFIX, MAXPATHLEN);
518 joinpath(prefix, lib_python);
519 }
520 else
521 reduce(prefix);
522
523 strncpy(zip_path, prefix, MAXPATHLEN);
524 zip_path[MAXPATHLEN] = '\0';
525 if (pfound > 0) { /* Use the reduced prefix returned by Py_GetPrefix() */
526 reduce(zip_path);
527 reduce(zip_path);
528 }
529 else
530 strncpy(zip_path, PREFIX, MAXPATHLEN);
531 joinpath(zip_path, "lib/python00.zip");
532 bufsz = strlen(zip_path); /* Replace "00" with version */
533 zip_path[bufsz - 6] = VERSION[0];
534 zip_path[bufsz - 5] = VERSION[2];
535
536 if (!(efound = search_for_exec_prefix(argv0_path, home))) {
537 if (!Py_FrozenFlag)
538 fprintf(stderr,
539 "Could not find platform dependent libraries <exec_prefix>\n");
540 strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
541 joinpath(exec_prefix, "lib/lib-dynload");
542 }
543 /* If we found EXEC_PREFIX do *not* reduce it! (Yet.) */
544
545 if ((!pfound || !efound) && !Py_FrozenFlag)
546 fprintf(stderr,
547 "Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]\n");
548
549 /* Calculate size of return buffer.
550 */
551 bufsz = 0;
552
553 if (rtpypath)
554 bufsz += strlen(rtpypath) + 1;
555
556 prefixsz = strlen(prefix) + 1;
557
558 while (1) {
559 char *delim = strchr(defpath, DELIM);
560
561 if (defpath[0] != SEP)
562 /* Paths are relative to prefix */
563 bufsz += prefixsz;
564
565 if (delim)
566 bufsz += delim - defpath + 1;
567 else {
568 bufsz += strlen(defpath) + 1;
569 break;
570 }
571 defpath = delim + 1;
572 }
573
574 bufsz += strlen(zip_path) + 1;
575 bufsz += strlen(exec_prefix) + 1;
576
577 /* This is the only malloc call in this file */
578 buf = (char *)PyMem_Malloc(bufsz);
579
580 if (buf == NULL) {
581 /* We can't exit, so print a warning and limp along */
582 fprintf(stderr, "Not enough memory for dynamic PYTHONPATH.\n");
583 fprintf(stderr, "Using default static PYTHONPATH.\n");
584 module_search_path = PYTHONPATH;
585 }
586 else {
587 /* Run-time value of $PYTHONPATH goes first */
588 if (rtpypath) {
589 strcpy(buf, rtpypath);
590 strcat(buf, delimiter);
591 }
592 else
593 buf[0] = '\0';
594
595 /* Next is the default zip path */
596 strcat(buf, zip_path);
597 strcat(buf, delimiter);
598
599 /* Next goes merge of compile-time $PYTHONPATH with
600 * dynamically located prefix.
601 */
602 defpath = pythonpath;
603 while (1) {
604 char *delim = strchr(defpath, DELIM);
605
606 if (defpath[0] != SEP) {
607 strcat(buf, prefix);
608 strcat(buf, separator);
609 }
610
611 if (delim) {
612 size_t len = delim - defpath + 1;
613 size_t end = strlen(buf) + len;
614 strncat(buf, defpath, len);
615 *(buf + end) = '\0';
616 }
617 else {
618 strcat(buf, defpath);
619 break;
620 }
621 defpath = delim + 1;
622 }
623 strcat(buf, delimiter);
624
625 /* Finally, on goes the directory for dynamic-load modules */
626 strcat(buf, exec_prefix);
627
628 /* And publish the results */
629 module_search_path = buf;
630 }
631
632 /* Reduce prefix and exec_prefix to their essence,
633 * e.g. /usr/local/lib/python1.5 is reduced to /usr/local.
634 * If we're loading relative to the build directory,
635 * return the compiled-in defaults instead.
636 */
637 if (pfound > 0) {
638 reduce(prefix);
639 reduce(prefix);
640 /* The prefix is the root directory, but reduce() chopped
641 * off the "/". */
642 if (!prefix[0])
643 strcpy(prefix, separator);
644 }
645 else
646 strncpy(prefix, PREFIX, MAXPATHLEN);
647
648 if (efound > 0) {
649 reduce(exec_prefix);
650 reduce(exec_prefix);
651 reduce(exec_prefix);
652 if (!exec_prefix[0])
653 strcpy(exec_prefix, separator);
654 }
655 else
656 strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
657 }
658
659
660 /* External interface */
661
662 char *
Py_GetPath(void)663 Py_GetPath(void)
664 {
665 if (!module_search_path)
666 calculate_path();
667 return module_search_path;
668 }
669
670 char *
Py_GetPrefix(void)671 Py_GetPrefix(void)
672 {
673 if (!module_search_path)
674 calculate_path();
675 return prefix;
676 }
677
678 char *
Py_GetExecPrefix(void)679 Py_GetExecPrefix(void)
680 {
681 if (!module_search_path)
682 calculate_path();
683 return exec_prefix;
684 }
685
686 char *
Py_GetProgramFullPath(void)687 Py_GetProgramFullPath(void)
688 {
689 if (!module_search_path)
690 calculate_path();
691 return progpath;
692 }
693
694
695 #ifdef __cplusplus
696 }
697 #endif
698
699