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
128static char prefix[MAXPATHLEN+1];
129static char exec_prefix[MAXPATHLEN+1];
130static char progpath[MAXPATHLEN+1];
131static char *module_search_path = NULL;
132static char lib_python[] = "lib/python" VERSION;
133
134static void
135reduce(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
144static int
145isfile(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
156static int
157ismodule(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
172static int
173isxfile(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
186static int
187isdir(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*/
207static void
208joinpath(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. */
229static void
230copy_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. */
247static void
248absolutize(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*/
261static int
262search_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*/
320static int
321search_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
370static void
371calculate_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
662char *
663Py_GetPath(void)
664{
665    if (!module_search_path)
666        calculate_path();
667    return module_search_path;
668}
669
670char *
671Py_GetPrefix(void)
672{
673    if (!module_search_path)
674        calculate_path();
675    return prefix;
676}
677
678char *
679Py_GetExecPrefix(void)
680{
681    if (!module_search_path)
682        calculate_path();
683    return exec_prefix;
684}
685
686char *
687Py_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