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cpython/PC/getpathp.c

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/* 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, it's 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
#include <sys/types.h>
#include <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 *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;
}
/* guarantees buffer will never overflow MAXPATHLEN+1 bytes */
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;
}
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;
}
#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);
}
/* 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]) {
int len = _tcslen(ppPaths[index]);
_tcsncpy(szCur, ppPaths[index], len);
szCur += len;
dataSize -= 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, dataSize+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
#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 (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 (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;
#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
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 machinepath and userpath, if set;
(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.
Extra rules:
- If PYTHONHOME is set (in any way) item (2) is ignored.
- If registry values are used, (3) and (4) are ignored.
*/
/* 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;
#ifdef MS_WINDOWS
if (userpath)
bufsz += strlen(userpath) + 1;
if (machinepath)
bufsz += strlen(machinepath) + 1;
#endif
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;
}
#ifdef MS_WINDOWS
if (machinepath)
free(machinepath);
if (userpath)
free(userpath);
#endif /* MS_WINDOWS */
return;
}
if (envpath) {
strcpy(buf, envpath);
buf = strchr(buf, '\0');
*buf++ = DELIM;
}
#ifdef MS_WINDOWS
if (userpath) {
strcpy(buf, userpath);
buf = strchr(buf, '\0');
*buf++ = DELIM;
free(userpath);
}
if (machinepath) {
strcpy(buf, machinepath);
buf = strchr(buf, '\0');
*buf++ = DELIM;
free(machinepath);
}
if (pythonhome == NULL) {
if (!skipdefault) {
strcpy(buf, PYTHONPATH);
buf = strchr(buf, '\0');
}
}
#else
if (pythonhome == NULL) {
strcpy(buf, PYTHONPATH);
buf = strchr(buf, '\0');
}
#endif /* MS_WINDOWS */
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';
/* Now to pull one last hack/trick. If sys.prefix is
empty, then try and find it somewhere on the paths
we calculated. We scan backwards, as our general policy
is that Python core directories are at the *end* of
sys.path. We assume that our "lib" directory is
on the path, and that our 'prefix' directory is
the parent of that.
*/
if (*prefix=='\0') {
char lookBuf[MAXPATHLEN+1];
char *look = buf - 1; /* 'buf' is at the end of the buffer */
while (1) {
int nchars;
char *lookEnd = look;
/* 'look' will end up one character before the
start of the path in question - even if this
is one character before the start of the buffer
*/
while (*look != DELIM && look >= module_search_path)
look--;
nchars = lookEnd-look;
strncpy(lookBuf, look+1, nchars);
lookBuf[nchars] = '\0';
/* Up one level to the parent */
reduce(lookBuf);
if (search_for_prefix(lookBuf, LANDMARK)) {
break;
}
/* If we are out of paths to search - give up */
if (look < module_search_path)
break;
look--;
}
}
}
/* 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;
}
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