/* Return the initial module search path. */

/* Used by DOS, OS/2, Windows 3.1, Windows 95/98, Windows NT. */

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

   PATH RULES FOR WINDOWS:

   This describes how sys.path is formed on Windows.  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 look in the registry for "application paths" - that is, sub-keys

     under the main PythonPath registry key.  These are added next (the

     order of sub-key processing is undefined).

     HKEY_CURRENT_USER is searched and added first.

     HKEY_LOCAL_MACHINE is searched and added next.

     (Note that all known installers only use HKLM, so HKCU is typically

     empty)

   * 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, lib-tk, 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, have not had a PYTHONPATH

     specified, and can't locate any Registry entries (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, and the core paths in the registry are

    ignored.  Other "application paths" in the registry are always read.

  * 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"

#ifdef MS_WINDOWS

#include <windows.h>

#include <tchar.h>

#endif

#ifdef HAVE_SYS_TYPES_H

#include <sys/types.h>

#endif /* HAVE_SYS_TYPES_H */

#ifdef HAVE_SYS_STAT_H

#include <sys/stat.h>

#endif /* HAVE_SYS_STAT_H */

#include <string.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

#define LANDMARK "lib\\os.py"

#endif

static char prefix[MAXPATHLEN+1];

static char progpath[MAXPATHLEN+1];

static char dllpath[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;

}

/* Assumes 'filename' MAXPATHLEN+1 bytes long - 

   may extend 'filename' by one character.

*/

static int

ismodule(char *filename)	/* Is module -- check for .pyc/.pyo too */

{

	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 ok;

	Py_ssize_t n;

	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;

}

#ifdef MS_WINDOWS

/* a string loaded from the DLL at startup.*/

extern const char *PyWin_DLLVersionString;

/* Load a PYTHONPATH value from the registry.

   Load from either HKEY_LOCAL_MACHINE or HKEY_CURRENT_USER.

   Works in both Unicode and 8bit environments.  Only uses the

   Ex family of functions so it also works with Windows CE.

   Returns NULL, or a pointer that should be freed.

   XXX - this code is pretty strange, as it used to also

   work on Win16, where the buffer sizes werent available

   in advance.  It could be simplied now Win16/Win32s is dead!

*/

static char *

getpythonregpath(HKEY keyBase, int skipcore)

{

	HKEY newKey = 0;

	DWORD dataSize = 0;

	DWORD numKeys = 0;

	LONG rc;

	char *retval = NULL;

	TCHAR *dataBuf = NULL;

	static const TCHAR keyPrefix[] = _T("Software\\Python\\PythonCore\\");

	static const TCHAR keySuffix[] = _T("\\PythonPath");

	size_t versionLen;

	DWORD index;

	TCHAR *keyBuf = NULL;

	TCHAR *keyBufPtr;

	TCHAR **ppPaths = NULL;

	/* Tried to use sysget("winver") but here is too early :-( */

	versionLen = _tcslen(PyWin_DLLVersionString);

	/* Space for all the chars, plus one \0 */

	keyBuf = keyBufPtr = malloc(sizeof(keyPrefix) + 

		                    sizeof(TCHAR)*(versionLen-1) + 

				    sizeof(keySuffix));

	if (keyBuf==NULL) goto done;

	memcpy(keyBufPtr, keyPrefix, sizeof(keyPrefix)-sizeof(TCHAR));

	keyBufPtr += sizeof(keyPrefix)/sizeof(TCHAR) - 1;

	memcpy(keyBufPtr, PyWin_DLLVersionString, versionLen * sizeof(TCHAR));

	keyBufPtr += versionLen;

	/* NULL comes with this one! */

	memcpy(keyBufPtr, keySuffix, sizeof(keySuffix));

	/* Open the root Python key */

	rc=RegOpenKeyEx(keyBase,

	                keyBuf, /* subkey */

	                0, /* reserved */

	                KEY_READ,

	                &newKey);

	if (rc!=ERROR_SUCCESS) goto done;

	/* Find out how big our core buffer is, and how many subkeys we have */

	rc = RegQueryInfoKey(newKey, NULL, NULL, NULL, &numKeys, NULL, NULL, 

	                NULL, NULL, &dataSize, NULL, NULL);

	if (rc!=ERROR_SUCCESS) goto done;

	if (skipcore) dataSize = 0; /* Only count core ones if we want them! */

	/* Allocate a temp array of char buffers, so we only need to loop 

	   reading the registry once

	*/

	ppPaths = malloc( sizeof(TCHAR *) * numKeys );

	if (ppPaths==NULL) goto done;

	memset(ppPaths, 0, sizeof(TCHAR *) * numKeys);

	/* Loop over all subkeys, allocating a temp sub-buffer. */

	for(index=0;index<numKeys;index++) {

		TCHAR keyBuf[MAX_PATH+1];

		HKEY subKey = 0;

		DWORD reqdSize = MAX_PATH+1;

		/* Get the sub-key name */

		DWORD rc = RegEnumKeyEx(newKey, index, keyBuf, &reqdSize,

		                        NULL, NULL, NULL, NULL );

		if (rc!=ERROR_SUCCESS) goto done;

		/* Open the sub-key */

		rc=RegOpenKeyEx(newKey,

						keyBuf, /* subkey */

						0, /* reserved */

						KEY_READ,

						&subKey);

		if (rc!=ERROR_SUCCESS) goto done;

		/* Find the value of the buffer size, malloc, then read it */

		RegQueryValueEx(subKey, NULL, 0, NULL, NULL, &reqdSize);

		if (reqdSize) {

			ppPaths[index] = malloc(reqdSize);

			if (ppPaths[index]) {

				RegQueryValueEx(subKey, NULL, 0, NULL, 

				                (LPBYTE)ppPaths[index], 

				                &reqdSize);

				dataSize += reqdSize + 1; /* 1 for the ";" */

			}

		}

		RegCloseKey(subKey);

	}

	/* return null if no path to return */

	if (dataSize == 0) goto done;

	/* original datasize from RegQueryInfo doesn't include the \0 */

	dataBuf = malloc((dataSize+1) * sizeof(TCHAR));

	if (dataBuf) {

		TCHAR *szCur = dataBuf;

		DWORD reqdSize = dataSize;

		/* Copy our collected strings */

		for (index=0;index<numKeys;index++) {

			if (index > 0) {

				*(szCur++) = _T(';');

				dataSize--;

			}

			if (ppPaths[index]) {

				Py_ssize_t len = _tcslen(ppPaths[index]);

				_tcsncpy(szCur, ppPaths[index], len);

				szCur += len;

				assert(dataSize > (DWORD)len);

				dataSize -= (DWORD)len;

			}

		}

		if (skipcore)

			*szCur = '\0';

		else {

			/* If we have no values, we dont need a ';' */

			if (numKeys) {

				*(szCur++) = _T(';');

				dataSize--;

			}

			/* Now append the core path entries - 

			   this will include the NULL 

			*/

			rc = RegQueryValueEx(newKey, NULL, 0, NULL, 

			                     (LPBYTE)szCur, &dataSize);

		}

		/* And set the result - caller must free 

		   If MBCS, it is fine as is.  If Unicode, allocate new

		   buffer and convert.

		*/

#ifdef UNICODE

		retval = (char *)malloc(reqdSize+1);

		if (retval)

			WideCharToMultiByte(CP_ACP, 0, 

					dataBuf, -1, /* source */ 

					retval, reqdSize+1, /* dest */

					NULL, NULL);

		free(dataBuf);

#else

		retval = dataBuf;

#endif

	}

done:

	/* Loop freeing my temp buffers */

	if (ppPaths) {

		for(index=0;index<numKeys;index++)

			if (ppPaths[index]) free(ppPaths[index]);

		free(ppPaths);

	}

	if (newKey)

		RegCloseKey(newKey);

	if (keyBuf)

		free(keyBuf);

	return retval;

}

#endif /* MS_WINDOWS */

static void

get_progpath(void)

{

	extern char *Py_GetProgramName(void);

	char *path = getenv("PATH");

	char *prog = Py_GetProgramName();

#ifdef MS_WINDOWS

	extern HANDLE PyWin_DLLhModule;

#ifdef UNICODE

	WCHAR wprogpath[MAXPATHLEN+1];

	/* Windows documents that GetModuleFileName() will "truncate",

	   but makes no mention of the null terminator.  Play it safe.

	   PLUS Windows itself defines MAX_PATH as the same, but anyway...

	*/

	wprogpath[MAXPATHLEN]=_T('\0');

	if (PyWin_DLLhModule &&

	    GetModuleFileName(PyWin_DLLhModule, wprogpath, MAXPATHLEN)) {

		WideCharToMultiByte(CP_ACP, 0, 

		                    wprogpath, -1, 

		                    dllpath, MAXPATHLEN+1, 

		                    NULL, NULL);

	}

	wprogpath[MAXPATHLEN]=_T('\0');

	if (GetModuleFileName(NULL, wprogpath, MAXPATHLEN)) {

		WideCharToMultiByte(CP_ACP, 0, 

		                    wprogpath, -1, 

		                    progpath, MAXPATHLEN+1, 

		                    NULL, NULL);

		return;

	}

#else

	/* static init of progpath ensures final char remains \0 */

	if (PyWin_DLLhModule)

		if (!GetModuleFileName(PyWin_DLLhModule, dllpath, MAXPATHLEN))

			dllpath[0] = 0;

	if (GetModuleFileName(NULL, progpath, MAXPATHLEN))

		return;

#endif

#endif

	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 */

				len = min(MAXPATHLEN,len);

				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 = Py_GETENV("PYTHONPATH");

#ifdef MS_WINDOWS

	int skiphome, skipdefault;

	char *machinepath = NULL;

	char *userpath = NULL;

	char zip_path[MAXPATHLEN+1];

	size_t len;

#endif

	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;

#ifdef MS_WINDOWS

	/* Calculate zip archive path */

	if (dllpath[0])		/* use name of python DLL */

		strncpy(zip_path, dllpath, MAXPATHLEN);

	else			/* use name of executable program */

		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;

	}

	skiphome = pythonhome==NULL ? 0 : 1;

	machinepath = getpythonregpath(HKEY_LOCAL_MACHINE, skiphome);

	userpath = getpythonregpath(HKEY_CURRENT_USER, skiphome);

	/* We only use the default relative PYTHONPATH if we havent

	   anything better to use! */

	skipdefault = envpath!=NULL || pythonhome!=NULL || \

		      machinepath!=NULL || userpath!=NULL;

#endif

	/* We need to construct a path from the following parts.

	   (1) the PYTHONPATH environment variable, if set;

	   (2) for Win32, the zip archive file path;

	   (3) for Win32, the machinepath and userpath, if set;

	   (4) the PYTHONPATH config macro, with the leading "."

	       of each component replaced with pythonhome, if set;

	   (5) the directory containing the executable (argv0_path).

	   The length calculation calculates #4 first.

	   Extra rules:

	   - If PYTHONHOME is set (in any way) item (3) is ignored.

	   - If registry values are used, (4) and (5) are ignored.

	*/

	/* Calculate size of return buffer */

	if (pythonhome != NULL) {

		char *p;

		bufsz = 1;	

		for (p = PYTHONPATH; *p; p++) {