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[python.git] / Modules / getpath.c
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1 /* Return the initial module search path. */
3 #include "Python.h"
4 #include "osdefs.h"
6 #include <sys/types.h>
7 #include <string.h>
9 #ifdef __APPLE__
10 #include <mach-o/dyld.h>
11 #endif
13 /* Search in some common locations for the associated Python libraries.
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.
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.
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 $PATH environment
33 * variable), the original argv[0] string is used.
35 * Next, the executable location is examined to see if it is a symbolic
36 * link. If so, the link is chased (correctly interpreting a relative
37 * pathname if one is found) and the directory of the link target is used.
39 * Finally, argv0_path is set to the directory containing the executable
40 * (i.e. the last component is stripped).
42 * With argv0_path in hand, we perform a number of steps. The same steps
43 * are performed for prefix and for exec_prefix, but with a different
44 * landmark.
46 * Step 1. Are we running python out of the build directory? This is
47 * checked by looking for a different kind of landmark relative to
48 * argv0_path. For prefix, the landmark's path is derived from the VPATH
49 * preprocessor variable (taking into account that its value is almost, but
50 * not quite, what we need). For exec_prefix, the landmark is
51 * Modules/Setup. If the landmark is found, we're done.
53 * For the remaining steps, the prefix landmark will always be
54 * lib/python$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.
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.
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.
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.
77 * That's it!
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.
94 #ifdef __cplusplus
95 extern "C" {
96 #endif
99 #ifndef VERSION
100 #define VERSION "2.1"
101 #endif
103 #ifndef VPATH
104 #define VPATH "."
105 #endif
107 #ifndef PREFIX
108 # ifdef __VMS
109 # define PREFIX ""
110 # else
111 # define PREFIX "/usr/local"
112 # endif
113 #endif
115 #ifndef EXEC_PREFIX
116 #define EXEC_PREFIX PREFIX
117 #endif
119 #ifndef PYTHONPATH
120 #define PYTHONPATH PREFIX "/lib/python" VERSION ":" \
121 EXEC_PREFIX "/lib/python" VERSION "/lib-dynload"
122 #endif
124 #ifndef LANDMARK
125 #define LANDMARK "os.py"
126 #endif
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;
134 static void
135 reduce(char *dir)
137 size_t i = strlen(dir);
138 while (i > 0 && dir[i] != SEP)
139 --i;
140 dir[i] = '\0';
144 static int
145 isfile(char *filename) /* Is file, not directory */
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;
156 static int
157 ismodule(char *filename) /* Is module -- check for .pyc/.pyo too */
159 if (isfile(filename))
160 return 1;
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;
168 return 0;
172 static int
173 isxfile(char *filename) /* Is executable file */
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;
186 static int
187 isdir(char *filename) /* Is directory */
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;
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.
207 static void
208 joinpath(char *buffer, char *stuff)
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;
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';
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
230 copy_absolute(char *path, char *p)
232 if (p[0] == SEP)
233 strcpy(path, p);
234 else {
235 getcwd(path, MAXPATHLEN);
236 if (p[0] == '.' && p[1] == SEP)
237 p += 2;
238 joinpath(path, p);
242 /* absolutize() requires that path be allocated at least MAXPATHLEN+1 bytes. */
243 static void
244 absolutize(char *path)
246 char buffer[MAXPATHLEN + 1];
248 if (path[0] == SEP)
249 return;
250 copy_absolute(buffer, path);
251 strcpy(path, buffer);
254 /* search_for_prefix requires that argv0_path be no more than MAXPATHLEN
255 bytes long.
257 static int
258 search_for_prefix(char *argv0_path, char *home)
260 size_t n;
261 char *vpath;
263 /* If PYTHONHOME is set, we believe it unconditionally */
264 if (home) {
265 char *delim;
266 strncpy(prefix, home, MAXPATHLEN);
267 delim = strchr(prefix, DELIM);
268 if (delim)
269 *delim = '\0';
270 joinpath(prefix, lib_python);
271 joinpath(prefix, LANDMARK);
272 return 1;
275 /* Check to see if argv[0] is in the build directory */
276 strcpy(prefix, argv0_path);
277 joinpath(prefix, "Modules/Setup");
278 if (isfile(prefix)) {
279 /* Check VPATH to see if argv0_path is in the build directory. */
280 vpath = VPATH;
281 strcpy(prefix, argv0_path);
282 joinpath(prefix, vpath);
283 joinpath(prefix, "Lib");
284 joinpath(prefix, LANDMARK);
285 if (ismodule(prefix))
286 return -1;
289 /* Search from argv0_path, until root is found */
290 copy_absolute(prefix, argv0_path);
291 do {
292 n = strlen(prefix);
293 joinpath(prefix, lib_python);
294 joinpath(prefix, LANDMARK);
295 if (ismodule(prefix))
296 return 1;
297 prefix[n] = '\0';
298 reduce(prefix);
299 } while (prefix[0]);
301 /* Look at configure's PREFIX */
302 strncpy(prefix, PREFIX, MAXPATHLEN);
303 joinpath(prefix, lib_python);
304 joinpath(prefix, LANDMARK);
305 if (ismodule(prefix))
306 return 1;
308 /* Fail */
309 return 0;
313 /* search_for_exec_prefix requires that argv0_path be no more than
314 MAXPATHLEN bytes long.
316 static int
317 search_for_exec_prefix(char *argv0_path, char *home)
319 size_t n;
321 /* If PYTHONHOME is set, we believe it unconditionally */
322 if (home) {
323 char *delim;
324 delim = strchr(home, DELIM);
325 if (delim)
326 strncpy(exec_prefix, delim+1, MAXPATHLEN);
327 else
328 strncpy(exec_prefix, home, MAXPATHLEN);
329 joinpath(exec_prefix, lib_python);
330 joinpath(exec_prefix, "lib-dynload");
331 return 1;
334 /* Check to see if argv[0] is in the build directory */
335 strcpy(exec_prefix, argv0_path);
336 joinpath(exec_prefix, "Modules/Setup");
337 if (isfile(exec_prefix)) {
338 reduce(exec_prefix);
339 return -1;
342 /* Search from argv0_path, until root is found */
343 copy_absolute(exec_prefix, argv0_path);
344 do {
345 n = strlen(exec_prefix);
346 joinpath(exec_prefix, lib_python);
347 joinpath(exec_prefix, "lib-dynload");
348 if (isdir(exec_prefix))
349 return 1;
350 exec_prefix[n] = '\0';
351 reduce(exec_prefix);
352 } while (exec_prefix[0]);
354 /* Look at configure's EXEC_PREFIX */
355 strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
356 joinpath(exec_prefix, lib_python);
357 joinpath(exec_prefix, "lib-dynload");
358 if (isdir(exec_prefix))
359 return 1;
361 /* Fail */
362 return 0;
366 static void
367 calculate_path(void)
369 extern char *Py_GetProgramName(void);
371 static char delimiter[2] = {DELIM, '\0'};
372 static char separator[2] = {SEP, '\0'};
373 char *pythonpath = PYTHONPATH;
374 char *rtpypath = Py_GETENV("PYTHONPATH");
375 char *home = Py_GetPythonHome();
376 char *path = getenv("PATH");
377 char *prog = Py_GetProgramName();
378 char argv0_path[MAXPATHLEN+1];
379 char zip_path[MAXPATHLEN+1];
380 int pfound, efound; /* 1 if found; -1 if found build directory */
381 char *buf;
382 size_t bufsz;
383 size_t prefixsz;
384 char *defpath = pythonpath;
385 #ifdef WITH_NEXT_FRAMEWORK
386 NSModule pythonModule;
387 #endif
388 #ifdef __APPLE__
389 #if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_4
390 uint32_t nsexeclength = MAXPATHLEN;
391 #else
392 unsigned long nsexeclength = MAXPATHLEN;
393 #endif
394 #endif
396 /* If there is no slash in the argv0 path, then we have to
397 * assume python is on the user's $PATH, since there's no
398 * other way to find a directory to start the search from. If
399 * $PATH isn't exported, you lose.
401 if (strchr(prog, SEP))
402 strncpy(progpath, prog, MAXPATHLEN);
403 #ifdef __APPLE__
404 /* On Mac OS X, if a script uses an interpreter of the form
405 * "#!/opt/python2.3/bin/python", the kernel only passes "python"
406 * as argv[0], which falls through to the $PATH search below.
407 * If /opt/python2.3/bin isn't in your path, or is near the end,
408 * this algorithm may incorrectly find /usr/bin/python. To work
409 * around this, we can use _NSGetExecutablePath to get a better
410 * hint of what the intended interpreter was, although this
411 * will fail if a relative path was used. but in that case,
412 * absolutize() should help us out below
414 else if(0 == _NSGetExecutablePath(progpath, &nsexeclength) && progpath[0] == SEP)
416 #endif /* __APPLE__ */
417 else if (path) {
418 while (1) {
419 char *delim = strchr(path, DELIM);
421 if (delim) {
422 size_t len = delim - path;
423 if (len > MAXPATHLEN)
424 len = MAXPATHLEN;
425 strncpy(progpath, path, len);
426 *(progpath + len) = '\0';
428 else
429 strncpy(progpath, path, MAXPATHLEN);
431 joinpath(progpath, prog);
432 if (isxfile(progpath))
433 break;
435 if (!delim) {
436 progpath[0] = '\0';
437 break;
439 path = delim + 1;
442 else
443 progpath[0] = '\0';
444 if (progpath[0] != SEP)
445 absolutize(progpath);
446 strncpy(argv0_path, progpath, MAXPATHLEN);
447 argv0_path[MAXPATHLEN] = '\0';
449 #ifdef WITH_NEXT_FRAMEWORK
450 /* On Mac OS X we have a special case if we're running from a framework.
451 ** This is because the python home should be set relative to the library,
452 ** which is in the framework, not relative to the executable, which may
453 ** be outside of the framework. Except when we're in the build directory...
455 pythonModule = NSModuleForSymbol(NSLookupAndBindSymbol("_Py_Initialize"));
456 /* Use dylib functions to find out where the framework was loaded from */
457 buf = (char *)NSLibraryNameForModule(pythonModule);
458 if (buf != NULL) {
459 /* We're in a framework. */
460 /* See if we might be in the build directory. The framework in the
461 ** build directory is incomplete, it only has the .dylib and a few
462 ** needed symlinks, it doesn't have the Lib directories and such.
463 ** If we're running with the framework from the build directory we must
464 ** be running the interpreter in the build directory, so we use the
465 ** build-directory-specific logic to find Lib and such.
467 strncpy(argv0_path, buf, MAXPATHLEN);
468 reduce(argv0_path);
469 joinpath(argv0_path, lib_python);
470 joinpath(argv0_path, LANDMARK);
471 if (!ismodule(argv0_path)) {
472 /* We are in the build directory so use the name of the
473 executable - we know that the absolute path is passed */
474 strncpy(argv0_path, prog, MAXPATHLEN);
476 else {
477 /* Use the location of the library as the progpath */
478 strncpy(argv0_path, buf, MAXPATHLEN);
481 #endif
483 #if HAVE_READLINK
485 char tmpbuffer[MAXPATHLEN+1];
486 int linklen = readlink(progpath, tmpbuffer, MAXPATHLEN);
487 while (linklen != -1) {
488 /* It's not null terminated! */
489 tmpbuffer[linklen] = '\0';
490 if (tmpbuffer[0] == SEP)
491 /* tmpbuffer should never be longer than MAXPATHLEN,
492 but extra check does not hurt */
493 strncpy(argv0_path, tmpbuffer, MAXPATHLEN);
494 else {
495 /* Interpret relative to progpath */
496 reduce(argv0_path);
497 joinpath(argv0_path, tmpbuffer);
499 linklen = readlink(argv0_path, tmpbuffer, MAXPATHLEN);
502 #endif /* HAVE_READLINK */
504 reduce(argv0_path);
505 /* At this point, argv0_path is guaranteed to be less than
506 MAXPATHLEN bytes long.
509 if (!(pfound = search_for_prefix(argv0_path, home))) {
510 if (!Py_FrozenFlag)
511 fprintf(stderr,
512 "Could not find platform independent libraries <prefix>\n");
513 strncpy(prefix, PREFIX, MAXPATHLEN);
514 joinpath(prefix, lib_python);
516 else
517 reduce(prefix);
519 strncpy(zip_path, prefix, MAXPATHLEN);
520 zip_path[MAXPATHLEN] = '\0';
521 if (pfound > 0) { /* Use the reduced prefix returned by Py_GetPrefix() */
522 reduce(zip_path);
523 reduce(zip_path);
525 else
526 strncpy(zip_path, PREFIX, MAXPATHLEN);
527 joinpath(zip_path, "lib/python00.zip");
528 bufsz = strlen(zip_path); /* Replace "00" with version */
529 zip_path[bufsz - 6] = VERSION[0];
530 zip_path[bufsz - 5] = VERSION[2];
532 if (!(efound = search_for_exec_prefix(argv0_path, home))) {
533 if (!Py_FrozenFlag)
534 fprintf(stderr,
535 "Could not find platform dependent libraries <exec_prefix>\n");
536 strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
537 joinpath(exec_prefix, "lib/lib-dynload");
539 /* If we found EXEC_PREFIX do *not* reduce it! (Yet.) */
541 if ((!pfound || !efound) && !Py_FrozenFlag)
542 fprintf(stderr,
543 "Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]\n");
545 /* Calculate size of return buffer.
547 bufsz = 0;
549 if (rtpypath)
550 bufsz += strlen(rtpypath) + 1;
552 prefixsz = strlen(prefix) + 1;
554 while (1) {
555 char *delim = strchr(defpath, DELIM);
557 if (defpath[0] != SEP)
558 /* Paths are relative to prefix */
559 bufsz += prefixsz;
561 if (delim)
562 bufsz += delim - defpath + 1;
563 else {
564 bufsz += strlen(defpath) + 1;
565 break;
567 defpath = delim + 1;
570 bufsz += strlen(zip_path) + 1;
571 bufsz += strlen(exec_prefix) + 1;
573 /* This is the only malloc call in this file */
574 buf = (char *)PyMem_Malloc(bufsz);
576 if (buf == NULL) {
577 /* We can't exit, so print a warning and limp along */
578 fprintf(stderr, "Not enough memory for dynamic PYTHONPATH.\n");
579 fprintf(stderr, "Using default static PYTHONPATH.\n");
580 module_search_path = PYTHONPATH;
582 else {
583 /* Run-time value of $PYTHONPATH goes first */
584 if (rtpypath) {
585 strcpy(buf, rtpypath);
586 strcat(buf, delimiter);
588 else
589 buf[0] = '\0';
591 /* Next is the default zip path */
592 strcat(buf, zip_path);
593 strcat(buf, delimiter);
595 /* Next goes merge of compile-time $PYTHONPATH with
596 * dynamically located prefix.
598 defpath = pythonpath;
599 while (1) {
600 char *delim = strchr(defpath, DELIM);
602 if (defpath[0] != SEP) {
603 strcat(buf, prefix);
604 strcat(buf, separator);
607 if (delim) {
608 size_t len = delim - defpath + 1;
609 size_t end = strlen(buf) + len;
610 strncat(buf, defpath, len);
611 *(buf + end) = '\0';
613 else {
614 strcat(buf, defpath);
615 break;
617 defpath = delim + 1;
619 strcat(buf, delimiter);
621 /* Finally, on goes the directory for dynamic-load modules */
622 strcat(buf, exec_prefix);
624 /* And publish the results */
625 module_search_path = buf;
628 /* Reduce prefix and exec_prefix to their essence,
629 * e.g. /usr/local/lib/python1.5 is reduced to /usr/local.
630 * If we're loading relative to the build directory,
631 * return the compiled-in defaults instead.
633 if (pfound > 0) {
634 reduce(prefix);
635 reduce(prefix);
636 /* The prefix is the root directory, but reduce() chopped
637 * off the "/". */
638 if (!prefix[0])
639 strcpy(prefix, separator);
641 else
642 strncpy(prefix, PREFIX, MAXPATHLEN);
644 if (efound > 0) {
645 reduce(exec_prefix);
646 reduce(exec_prefix);
647 reduce(exec_prefix);
648 if (!exec_prefix[0])
649 strcpy(exec_prefix, separator);
651 else
652 strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
656 /* External interface */
658 char *
659 Py_GetPath(void)
661 if (!module_search_path)
662 calculate_path();
663 return module_search_path;
666 char *
667 Py_GetPrefix(void)
669 if (!module_search_path)
670 calculate_path();
671 return prefix;
674 char *
675 Py_GetExecPrefix(void)
677 if (!module_search_path)
678 calculate_path();
679 return exec_prefix;
682 char *
683 Py_GetProgramFullPath(void)
685 if (!module_search_path)
686 calculate_path();
687 return progpath;
691 #ifdef __cplusplus
693 #endif