summaryrefslogtreecommitdiffstats
path: root/PC/os2emx/getpathp.c
blob: 0d73774ce0e957a573c18ccfd02589d24aa8aae3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418

/* Return the initial module search path. */
/* This version used by OS/2+EMX */

/* ----------------------------------------------------------------
   PATH RULES FOR OS/2+EMX:
   This describes how sys.path is formed on OS/2+EMX.  It describes the
   functionality, not the implementation (ie, the order in which these
   are actually fetched is different)

   * Python always adds an empty entry at the start, which corresponds
     to the current directory.

   * If the PYTHONPATH env. var. exists, its entries are added next.

   * We attempt to locate the "Python Home" - if the PYTHONHOME env var
     is set, we believe it.  Otherwise, we use the path of our host .EXE's
     to try and locate our "landmark" (lib\\os.py) and deduce our home.
     - If we DO have a Python Home: The relevant sub-directories (Lib,
       plat-win, etc) are based on the Python Home
     - If we DO NOT have a Python Home, the core Python Path is
       loaded from the registry.  This is the main PythonPath key,
       and both HKLM and HKCU are combined to form the path)

   * Iff - we can not locate the Python Home, and have not had a PYTHONPATH
     specified (ie, we have _nothing_ we can assume is a good path), a
     default path with relative entries is used (eg. .\Lib;.\plat-win, etc)


  The end result of all this is:
  * When running python.exe, or any other .exe in the main Python directory
    (either an installed version, or directly from the PCbuild directory),
    the core path is deduced.

  * When Python is hosted in another exe (different directory, embedded via
    COM, etc), the Python Home will not be deduced, so the core path from
    the registry is used.  Other "application paths "in the registry are
    always read.

  * If Python can't find its home and there is no registry (eg, frozen
    exe, some very strange installation setup) you get a path with
    some default, but relative, paths.

   ---------------------------------------------------------------- */


#include "Python.h"
#include "osdefs.h"

#ifndef PYOS_OS2
#error This file only compilable on OS/2
#endif

#define INCL_DOS
#include <os2.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>

#if HAVE_UNISTD_H
#include <unistd.h>
#endif /* HAVE_UNISTD_H */

/* Search in some common locations for the associated Python libraries.
 *
 * Py_GetPath() tries to return a sensible Python module search path.
 *
 * The approach is an adaptation for Windows of the strategy used in
 * ../Modules/getpath.c; it uses the Windows Registry as one of its
 * information sources.
 */

#ifndef LANDMARK
#if defined(PYCC_GCC)
#define LANDMARK "lib/os.py"
#else
#define LANDMARK "lib\\os.py"
#endif
#endif

static char prefix[MAXPATHLEN+1];
static char progpath[MAXPATHLEN+1];
static char *module_search_path = NULL;


static int
is_sep(char ch) /* determine if "ch" is a separator character */
{
#ifdef ALTSEP
    return ch == SEP || ch == ALTSEP;
#else
    return ch == SEP;
#endif
}

/* assumes 'dir' null terminated in bounds.
 * Never writes beyond existing terminator.
 */
static void
reduce(char *dir)
{
    size_t i = strlen(dir);
    while (i > 0 && !is_sep(dir[i]))
        --i;
    dir[i] = '\0';
}

static int
exists(char *filename)
{
    struct stat buf;
    return stat(filename, &buf) == 0;
}

/* Is module  (check for .pyc/.pyo too)
 * Assumes 'filename' MAXPATHLEN+1 bytes long -
 * may extend 'filename' by one character.
 */
static int
ismodule(char *filename)
{
    if (exists(filename))
        return 1;

    /* Check for the compiled version of prefix. */
    if (strlen(filename) < MAXPATHLEN) {
        strcat(filename, Py_OptimizeFlag ? "o" : "c");
        if (exists(filename))
            return 1;
    }
    return 0;
}

/* Add a path component, by appending stuff to buffer.
   buffer must have at least MAXPATHLEN + 1 bytes allocated, and contain a
   NUL-terminated string with no more than MAXPATHLEN characters (not counting
   the trailing NUL).  It's a fatal error if it contains a string longer than
   that (callers must be careful!).  If these requirements are met, it's
   guaranteed that buffer will still be a NUL-terminated string with no more
   than MAXPATHLEN characters at exit.  If stuff is too long, only as much of
   stuff as fits will be appended.
*/

static void
join(char *buffer, char *stuff)
{
    size_t n, k;
    if (is_sep(stuff[0]))
        n = 0;
    else {
        n = strlen(buffer);
        if (n > 0 && !is_sep(buffer[n-1]) && n < MAXPATHLEN)
            buffer[n++] = SEP;
    }
    if (n > MAXPATHLEN)
        Py_FatalError("buffer overflow in getpathp.c's joinpath()");
    k = strlen(stuff);
    if (n + k > MAXPATHLEN)
        k = MAXPATHLEN - n;
    strncpy(buffer+n, stuff, k);
    buffer[n+k] = '\0';
}

/* gotlandmark only called by search_for_prefix, which ensures
 * 'prefix' is null terminated in bounds.  join() ensures
 * 'landmark' can not overflow prefix if too long.
 */
static int
gotlandmark(char *landmark)
{
    int n, ok;

    n = strlen(prefix);
    join(prefix, landmark);
    ok = ismodule(prefix);
    prefix[n] = '\0';
    return ok;
}

/* assumes argv0_path is MAXPATHLEN+1 bytes long, already \0 term'd.
 * assumption provided by only caller, calculate_path()
 */
static int
search_for_prefix(char *argv0_path, char *landmark)
{
    /* Search from argv0_path, until landmark is found */
    strcpy(prefix, argv0_path);
    do {
        if (gotlandmark(landmark))
            return 1;
        reduce(prefix);
    } while (prefix[0]);
    return 0;
}


static void
get_progpath(void)
{
    extern char *Py_GetProgramName(void);
    char *path = getenv("PATH");
    char *prog = Py_GetProgramName();

    PPIB pib;
    if ((DosGetInfoBlocks(NULL, &pib) == 0) &&
        (DosQueryModuleName(pib->pib_hmte, sizeof(progpath), progpath) == 0))
        return;

    if (prog == NULL || *prog == '\0')
        prog = "python";

    /* If there is no slash in the argv0 path, then we have to
     * assume python is on the user's $PATH, since there's no
     * other way to find a directory to start the search from.  If
     * $PATH isn't exported, you lose.
     */
#ifdef ALTSEP
    if (strchr(prog, SEP) || strchr(prog, ALTSEP))
#else
    if (strchr(prog, SEP))
#endif
        strncpy(progpath, prog, MAXPATHLEN);
    else if (path) {
        while (1) {
            char *delim = strchr(path, DELIM);

            if (delim) {
                size_t len = delim - path;
                /* ensure we can't overwrite buffer */
#if !defined(PYCC_GCC)
                len = min(MAXPATHLEN,len);
#else
                len = MAXPATHLEN < len ? MAXPATHLEN : len;
#endif
                strncpy(progpath, path, len);
                *(progpath + len) = '\0';
            }
            else
                strncpy(progpath, path, MAXPATHLEN);

            /* join() is safe for MAXPATHLEN+1 size buffer */
            join(progpath, prog);
            if (exists(progpath))
                break;

            if (!delim) {
                progpath[0] = '\0';
                break;
            }
            path = delim + 1;
        }
    }
    else
        progpath[0] = '\0';
}

static void
calculate_path(void)
{
    char argv0_path[MAXPATHLEN+1];
    char *buf;
    size_t bufsz;
    char *pythonhome = Py_GetPythonHome();
    char *envpath = getenv("PYTHONPATH");
    char zip_path[MAXPATHLEN+1];
    size_t len;

    get_progpath();
    /* progpath guaranteed \0 terminated in MAXPATH+1 bytes. */
    strcpy(argv0_path, progpath);
    reduce(argv0_path);
    if (pythonhome == NULL || *pythonhome == '\0') {
        if (search_for_prefix(argv0_path, LANDMARK))
            pythonhome = prefix;
        else
            pythonhome = NULL;
    }
    else
        strncpy(prefix, pythonhome, MAXPATHLEN);

    if (envpath && *envpath == '\0')
        envpath = NULL;

    /* Calculate zip archive path */
    strncpy(zip_path, progpath, MAXPATHLEN);
    zip_path[MAXPATHLEN] = '\0';
    len = strlen(zip_path);
    if (len > 4) {
        zip_path[len-3] = 'z';  /* change ending to "zip" */
        zip_path[len-2] = 'i';
        zip_path[len-1] = 'p';
    }
    else {
        zip_path[0] = 0;
    }

    /* We need to construct a path from the following parts.
     * (1) the PYTHONPATH environment variable, if set;
     * (2) the zip archive file path;
     * (3) the PYTHONPATH config macro, with the leading "."
     *     of each component replaced with pythonhome, if set;
     * (4) the directory containing the executable (argv0_path).
     * The length calculation calculates #3 first.
     */

    /* Calculate size of return buffer */
    if (pythonhome != NULL) {
        char *p;
        bufsz = 1;
        for (p = PYTHONPATH; *p; p++) {
            if (*p == DELIM)
                bufsz++; /* number of DELIM plus one */
        }
        bufsz *= strlen(pythonhome);
    }
    else
        bufsz = 0;
    bufsz += strlen(PYTHONPATH) + 1;
    bufsz += strlen(argv0_path) + 1;
    bufsz += strlen(zip_path) + 1;
    if (envpath != NULL)
        bufsz += strlen(envpath) + 1;

    module_search_path = buf = malloc(bufsz);
    if (buf == NULL) {
        /* We can't exit, so print a warning and limp along */
        fprintf(stderr, "Can't malloc dynamic PYTHONPATH.\n");
        if (envpath) {
            fprintf(stderr, "Using environment $PYTHONPATH.\n");
            module_search_path = envpath;
        }
        else {
            fprintf(stderr, "Using default static path.\n");
            module_search_path = PYTHONPATH;
        }
        return;
    }

    if (envpath) {
        strcpy(buf, envpath);
        buf = strchr(buf, '\0');
        *buf++ = DELIM;
    }
    if (zip_path[0]) {
        strcpy(buf, zip_path);
        buf = strchr(buf, '\0');
        *buf++ = DELIM;
    }

    if (pythonhome == NULL) {
        strcpy(buf, PYTHONPATH);
        buf = strchr(buf, '\0');
    }
    else {
        char *p = PYTHONPATH;
        char *q;
        size_t n;
        for (;;) {
            q = strchr(p, DELIM);
            if (q == NULL)
                n = strlen(p);
            else
                n = q-p;
            if (p[0] == '.' && is_sep(p[1])) {
                strcpy(buf, pythonhome);
                buf = strchr(buf, '\0');
                p++;
                n--;
            }
            strncpy(buf, p, n);
            buf += n;
            if (q == NULL)
                break;
            *buf++ = DELIM;
            p = q+1;
        }
    }
    if (argv0_path) {
        *buf++ = DELIM;
        strcpy(buf, argv0_path);
        buf = strchr(buf, '\0');
    }
    *buf = '\0';
}


/* External interface */

char *
Py_GetPath(void)
{
    if (!module_search_path)
        calculate_path();
    return module_search_path;
}

char *
Py_GetPrefix(void)
{
    if (!module_search_path)
        calculate_path();
    return prefix;
}

char *
Py_GetExecPrefix(void)
{
    return Py_GetPrefix();
}

char *
Py_GetProgramFullPath(void)
{
    if (!module_search_path)
        calculate_path();
    return progpath;
}