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/PC/os2emx/getpathp.c

http://unladen-swallow.googlecode.com/
C | 418 lines | 278 code | 45 blank | 95 comment | 73 complexity | 380140eda24675881ec9f76f01f7bb7a MD5 | raw file
  1
  2/* Return the initial module search path. */
  3/* This version used by OS/2+EMX */
  4
  5/* ----------------------------------------------------------------
  6   PATH RULES FOR OS/2+EMX:
  7   This describes how sys.path is formed on OS/2+EMX.  It describes the 
  8   functionality, not the implementation (ie, the order in which these 
  9   are actually fetched is different)
 10
 11   * Python always adds an empty entry at the start, which corresponds
 12     to the current directory.
 13
 14   * If the PYTHONPATH env. var. exists, its entries are added next.
 15
 16   * We attempt to locate the "Python Home" - if the PYTHONHOME env var
 17     is set, we believe it.  Otherwise, we use the path of our host .EXE's
 18     to try and locate our "landmark" (lib\\os.py) and deduce our home.
 19     - If we DO have a Python Home: The relevant sub-directories (Lib, 
 20       plat-win, lib-tk, etc) are based on the Python Home
 21     - If we DO NOT have a Python Home, the core Python Path is
 22       loaded from the registry.  This is the main PythonPath key, 
 23       and both HKLM and HKCU are combined to form the path)
 24
 25   * Iff - we can not locate the Python Home, and have not had a PYTHONPATH
 26     specified (ie, we have _nothing_ we can assume is a good path), a
 27     default path with relative entries is used (eg. .\Lib;.\plat-win, etc)
 28
 29
 30  The end result of all this is:
 31  * When running python.exe, or any other .exe in the main Python directory
 32    (either an installed version, or directly from the PCbuild directory),
 33    the core path is deduced.
 34
 35  * When Python is hosted in another exe (different directory, embedded via 
 36    COM, etc), the Python Home will not be deduced, so the core path from
 37    the registry is used.  Other "application paths "in the registry are 
 38    always read.
 39
 40  * If Python can't find its home and there is no registry (eg, frozen
 41    exe, some very strange installation setup) you get a path with
 42    some default, but relative, paths.
 43
 44   ---------------------------------------------------------------- */
 45
 46
 47#include "Python.h"
 48#include "osdefs.h"
 49
 50#ifndef PYOS_OS2
 51#error This file only compilable on OS/2
 52#endif
 53
 54#define INCL_DOS
 55#include <os2.h>
 56
 57#include <sys/types.h>
 58#include <sys/stat.h>
 59#include <string.h>
 60
 61#if HAVE_UNISTD_H
 62#include <unistd.h>
 63#endif /* HAVE_UNISTD_H */
 64
 65/* Search in some common locations for the associated Python libraries.
 66 *
 67 * Py_GetPath() tries to return a sensible Python module search path.
 68 *
 69 * The approach is an adaptation for Windows of the strategy used in
 70 * ../Modules/getpath.c; it uses the Windows Registry as one of its
 71 * information sources.
 72 */
 73
 74#ifndef LANDMARK
 75#if defined(PYCC_GCC)
 76#define LANDMARK "lib/os.py"
 77#else
 78#define LANDMARK "lib\\os.py"
 79#endif
 80#endif
 81
 82static char prefix[MAXPATHLEN+1];
 83static char progpath[MAXPATHLEN+1];
 84static char *module_search_path = NULL;
 85
 86
 87static int
 88is_sep(char ch)	/* determine if "ch" is a separator character */
 89{
 90#ifdef ALTSEP
 91	return ch == SEP || ch == ALTSEP;
 92#else
 93	return ch == SEP;
 94#endif
 95}
 96
 97/* assumes 'dir' null terminated in bounds.
 98 * Never writes beyond existing terminator.
 99 */
100static void
101reduce(char *dir)
102{
103	size_t i = strlen(dir);
104	while (i > 0 && !is_sep(dir[i]))
105		--i;
106	dir[i] = '\0';
107}
108	
109static int
110exists(char *filename)
111{
112	struct stat buf;
113	return stat(filename, &buf) == 0;
114}
115
116/* Is module  (check for .pyc/.pyo too)
117 * Assumes 'filename' MAXPATHLEN+1 bytes long - 
118 * may extend 'filename' by one character.
119 */
120static int
121ismodule(char *filename)
122{
123	if (exists(filename))
124		return 1;
125
126	/* Check for the compiled version of prefix. */
127	if (strlen(filename) < MAXPATHLEN) {
128		strcat(filename, Py_OptimizeFlag ? "o" : "c");
129		if (exists(filename))
130			return 1;
131	}
132	return 0;
133}
134
135/* Add a path component, by appending stuff to buffer.
136   buffer must have at least MAXPATHLEN + 1 bytes allocated, and contain a
137   NUL-terminated string with no more than MAXPATHLEN characters (not counting
138   the trailing NUL).  It's a fatal error if it contains a string longer than
139   that (callers must be careful!).  If these requirements are met, it's
140   guaranteed that buffer will still be a NUL-terminated string with no more
141   than MAXPATHLEN characters at exit.  If stuff is too long, only as much of
142   stuff as fits will be appended.
143*/
144
145static void
146join(char *buffer, char *stuff)
147{
148	size_t n, k;
149	if (is_sep(stuff[0]))
150		n = 0;
151	else {
152		n = strlen(buffer);
153		if (n > 0 && !is_sep(buffer[n-1]) && n < MAXPATHLEN)
154			buffer[n++] = SEP;
155	}
156	if (n > MAXPATHLEN)
157		Py_FatalError("buffer overflow in getpathp.c's joinpath()");
158	k = strlen(stuff);
159	if (n + k > MAXPATHLEN)
160		k = MAXPATHLEN - n;
161	strncpy(buffer+n, stuff, k);
162	buffer[n+k] = '\0';
163}
164
165/* gotlandmark only called by search_for_prefix, which ensures
166 * 'prefix' is null terminated in bounds.  join() ensures
167 * 'landmark' can not overflow prefix if too long.
168 */
169static int
170gotlandmark(char *landmark)
171{
172	int n, ok;
173
174	n = strlen(prefix);
175	join(prefix, landmark);
176	ok = ismodule(prefix);
177	prefix[n] = '\0';
178	return ok;
179}
180
181/* assumes argv0_path is MAXPATHLEN+1 bytes long, already \0 term'd. 
182 * assumption provided by only caller, calculate_path()
183 */
184static int
185search_for_prefix(char *argv0_path, char *landmark)
186{
187	/* Search from argv0_path, until landmark is found */
188	strcpy(prefix, argv0_path);
189	do {
190		if (gotlandmark(landmark))
191			return 1;
192		reduce(prefix);
193	} while (prefix[0]);
194	return 0;
195}
196
197
198static void
199get_progpath(void)
200{
201	extern char *Py_GetProgramName(void);
202	char *path = getenv("PATH");
203	char *prog = Py_GetProgramName();
204
205	PPIB pib;
206	if ((DosGetInfoBlocks(NULL, &pib) == 0) &&
207	    (DosQueryModuleName(pib->pib_hmte, sizeof(progpath), progpath) == 0))
208		return;
209
210	if (prog == NULL || *prog == '\0')
211		prog = "python";
212
213	/* If there is no slash in the argv0 path, then we have to
214	 * assume python is on the user's $PATH, since there's no
215	 * other way to find a directory to start the search from.  If
216	 * $PATH isn't exported, you lose.
217	 */
218#ifdef ALTSEP
219	if (strchr(prog, SEP) || strchr(prog, ALTSEP))
220#else
221	if (strchr(prog, SEP))
222#endif
223		strncpy(progpath, prog, MAXPATHLEN);
224	else if (path) {
225		while (1) {
226			char *delim = strchr(path, DELIM);
227
228			if (delim) {
229				size_t len = delim - path;
230				/* ensure we can't overwrite buffer */
231#if !defined(PYCC_GCC)
232				len = min(MAXPATHLEN,len);
233#else
234				len = MAXPATHLEN < len ? MAXPATHLEN : len;
235#endif
236				strncpy(progpath, path, len);
237				*(progpath + len) = '\0';
238			}
239			else
240				strncpy(progpath, path, MAXPATHLEN);
241
242			/* join() is safe for MAXPATHLEN+1 size buffer */
243			join(progpath, prog);
244			if (exists(progpath))
245				break;
246
247			if (!delim) {
248				progpath[0] = '\0';
249				break;
250			}
251			path = delim + 1;
252		}
253	}
254	else
255		progpath[0] = '\0';
256}
257
258static void
259calculate_path(void)
260{
261	char argv0_path[MAXPATHLEN+1];
262	char *buf;
263	size_t bufsz;
264	char *pythonhome = Py_GetPythonHome();
265	char *envpath = getenv("PYTHONPATH");
266	char zip_path[MAXPATHLEN+1];
267	size_t len;
268
269	get_progpath();
270	/* progpath guaranteed \0 terminated in MAXPATH+1 bytes. */
271	strcpy(argv0_path, progpath);
272	reduce(argv0_path);
273	if (pythonhome == NULL || *pythonhome == '\0') {
274		if (search_for_prefix(argv0_path, LANDMARK))
275			pythonhome = prefix;
276		else
277			pythonhome = NULL;
278	}
279	else
280		strncpy(prefix, pythonhome, MAXPATHLEN);
281
282	if (envpath && *envpath == '\0')
283		envpath = NULL;
284
285	/* Calculate zip archive path */
286	strncpy(zip_path, progpath, MAXPATHLEN);
287	zip_path[MAXPATHLEN] = '\0';
288	len = strlen(zip_path);
289	if (len > 4) {
290		zip_path[len-3] = 'z';  /* change ending to "zip" */
291		zip_path[len-2] = 'i';
292		zip_path[len-1] = 'p';
293	}
294	else {
295		zip_path[0] = 0;
296	}
297
298	/* We need to construct a path from the following parts.
299	 * (1) the PYTHONPATH environment variable, if set;
300	 * (2) the zip archive file path;
301	 * (3) the PYTHONPATH config macro, with the leading "."
302	 *     of each component replaced with pythonhome, if set;
303	 * (4) the directory containing the executable (argv0_path).
304	 * The length calculation calculates #3 first.
305	 */
306
307	/* Calculate size of return buffer */
308	if (pythonhome != NULL) {
309		char *p;
310		bufsz = 1;	
311		for (p = PYTHONPATH; *p; p++) {
312			if (*p == DELIM)
313				bufsz++; /* number of DELIM plus one */
314		}
315		bufsz *= strlen(pythonhome);
316	}
317	else
318		bufsz = 0;
319	bufsz += strlen(PYTHONPATH) + 1;
320	bufsz += strlen(argv0_path) + 1;
321	bufsz += strlen(zip_path) + 1;
322	if (envpath != NULL)
323		bufsz += strlen(envpath) + 1;
324
325	module_search_path = buf = malloc(bufsz);
326	if (buf == NULL) {
327		/* We can't exit, so print a warning and limp along */
328		fprintf(stderr, "Can't malloc dynamic PYTHONPATH.\n");
329		if (envpath) {
330			fprintf(stderr, "Using environment $PYTHONPATH.\n");
331			module_search_path = envpath;
332		}
333		else {
334			fprintf(stderr, "Using default static path.\n");
335			module_search_path = PYTHONPATH;
336		}
337		return;
338	}
339
340	if (envpath) {
341		strcpy(buf, envpath);
342		buf = strchr(buf, '\0');
343		*buf++ = DELIM;
344	}
345	if (zip_path[0]) {
346		strcpy(buf, zip_path);
347		buf = strchr(buf, '\0');
348		*buf++ = DELIM;
349	}
350
351	if (pythonhome == NULL) {
352		strcpy(buf, PYTHONPATH);
353		buf = strchr(buf, '\0');
354	}
355	else {
356		char *p = PYTHONPATH;
357		char *q;
358		size_t n;
359		for (;;) {
360			q = strchr(p, DELIM);
361			if (q == NULL)
362				n = strlen(p);
363			else
364				n = q-p;
365			if (p[0] == '.' && is_sep(p[1])) {
366				strcpy(buf, pythonhome);
367				buf = strchr(buf, '\0');
368				p++;
369				n--;
370			}
371			strncpy(buf, p, n);
372			buf += n;
373			if (q == NULL)
374				break;
375			*buf++ = DELIM;
376			p = q+1;
377		}
378	}
379	if (argv0_path) {
380		*buf++ = DELIM;
381		strcpy(buf, argv0_path);
382		buf = strchr(buf, '\0');
383	}
384	*buf = '\0';
385}
386
387
388/* External interface */
389
390char *
391Py_GetPath(void)
392{
393	if (!module_search_path)
394		calculate_path();
395	return module_search_path;
396}
397
398char *
399Py_GetPrefix(void)
400{
401	if (!module_search_path)
402		calculate_path();
403	return prefix;
404}
405
406char *
407Py_GetExecPrefix(void)
408{
409	return Py_GetPrefix();
410}
411
412char *
413Py_GetProgramFullPath(void)
414{
415	if (!module_search_path)
416		calculate_path();
417	return progpath;
418}