mirror of https://github.com/python/cpython
406 lines
9.1 KiB
C
406 lines
9.1 KiB
C
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/* Return the initial module search path. */
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/* This version used by OS/2+EMX */
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/* ----------------------------------------------------------------
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PATH RULES FOR OS/2+EMX:
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This describes how sys.path is formed on OS/2+EMX. It describes the
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functionality, not the implementation (ie, the order in which these
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are actually fetched is different)
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* Python always adds an empty entry at the start, which corresponds
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to the current directory.
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* If the PYTHONPATH env. var. exists, it's entries are added next.
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* We attempt to locate the "Python Home" - if the PYTHONHOME env var
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is set, we believe it. Otherwise, we use the path of our host .EXE's
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to try and locate our "landmark" (lib\\os.py) and deduce our home.
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- If we DO have a Python Home: The relevant sub-directories (Lib,
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plat-win, lib-tk, etc) are based on the Python Home
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- If we DO NOT have a Python Home, the core Python Path is
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loaded from the registry. This is the main PythonPath key,
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and both HKLM and HKCU are combined to form the path)
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* Iff - we can not locate the Python Home, and have not had a PYTHONPATH
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specified (ie, we have _nothing_ we can assume is a good path), a
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default path with relative entries is used (eg. .\Lib;.\plat-win, etc)
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The end result of all this is:
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* When running python.exe, or any other .exe in the main Python directory
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(either an installed version, or directly from the PCbuild directory),
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the core path is deduced.
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* When Python is hosted in another exe (different directory, embedded via
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COM, etc), the Python Home will not be deduced, so the core path from
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the registry is used. Other "application paths "in the registry are
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always read.
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* If Python can't find its home and there is no registry (eg, frozen
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exe, some very strange installation setup) you get a path with
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some default, but relative, paths.
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---------------------------------------------------------------- */
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#include "Python.h"
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#include "osdefs.h"
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#ifndef PYOS_OS2
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#error This file only compilable on OS/2
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#endif
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#define INCL_DOS
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#include <os2.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <string.h>
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif /* HAVE_UNISTD_H */
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/* Search in some common locations for the associated Python libraries.
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*
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* Py_GetPath() tries to return a sensible Python module search path.
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*
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* The approach is an adaptation for Windows of the strategy used in
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* ../Modules/getpath.c; it uses the Windows Registry as one of its
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* information sources.
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*/
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#ifndef LANDMARK
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#if defined(PYCC_GCC)
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#define LANDMARK "lib/os.py"
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#else
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#define LANDMARK "lib\\os.py"
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#endif
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#endif
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static char prefix[MAXPATHLEN+1];
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static char progpath[MAXPATHLEN+1];
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static char *module_search_path = NULL;
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static int
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is_sep(char ch) /* determine if "ch" is a separator character */
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{
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#ifdef ALTSEP
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return ch == SEP || ch == ALTSEP;
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#else
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return ch == SEP;
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#endif
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}
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/* assumes 'dir' null terminated in bounds. Never writes
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beyond existing terminator.
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*/
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static void
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reduce(char *dir)
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{
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size_t i = strlen(dir);
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while (i > 0 && !is_sep(dir[i]))
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--i;
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dir[i] = '\0';
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}
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static int
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exists(char *filename)
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{
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struct stat buf;
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return stat(filename, &buf) == 0;
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}
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/* Assumes 'filename' MAXPATHLEN+1 bytes long -
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may extend 'filename' by one character.
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*/
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static int
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ismodule(char *filename) /* Is module -- check for .pyc/.pyo too */
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{
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if (exists(filename))
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return 1;
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/* Check for the compiled version of prefix. */
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if (strlen(filename) < MAXPATHLEN) {
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strcat(filename, Py_OptimizeFlag ? "o" : "c");
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if (exists(filename))
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return 1;
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}
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return 0;
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}
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/* guarantees buffer will never overflow MAXPATHLEN+1 bytes */
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static void
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join(char *buffer, char *stuff)
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{
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size_t n, k;
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if (is_sep(stuff[0]))
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n = 0;
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else {
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n = strlen(buffer);
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if (n > 0 && !is_sep(buffer[n-1]) && n < MAXPATHLEN)
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buffer[n++] = SEP;
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}
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k = strlen(stuff);
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if (n + k > MAXPATHLEN)
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k = MAXPATHLEN - n;
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strncpy(buffer+n, stuff, k);
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buffer[n+k] = '\0';
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}
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/* gotlandmark only called by search_for_prefix, which ensures
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'prefix' is null terminated in bounds. join() ensures
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'landmark' can not overflow prefix if too long.
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*/
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static int
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gotlandmark(char *landmark)
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{
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int n, ok;
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n = strlen(prefix);
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join(prefix, landmark);
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ok = ismodule(prefix);
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prefix[n] = '\0';
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return ok;
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}
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/* assumes argv0_path is MAXPATHLEN+1 bytes long, already \0 term'd.
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assumption provided by only caller, calculate_path() */
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static int
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search_for_prefix(char *argv0_path, char *landmark)
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{
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/* Search from argv0_path, until landmark is found */
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strcpy(prefix, argv0_path);
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do {
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if (gotlandmark(landmark))
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return 1;
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reduce(prefix);
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} while (prefix[0]);
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return 0;
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}
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static void
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get_progpath(void)
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{
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extern char *Py_GetProgramName(void);
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char *path = getenv("PATH");
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char *prog = Py_GetProgramName();
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PPIB pib;
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if ((DosGetInfoBlocks(NULL, &pib) == 0) &&
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(DosQueryModuleName(pib->pib_hmte, sizeof(progpath), progpath) == 0))
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return;
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if (prog == NULL || *prog == '\0')
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prog = "python";
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/* If there is no slash in the argv0 path, then we have to
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* assume python is on the user's $PATH, since there's no
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* other way to find a directory to start the search from. If
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* $PATH isn't exported, you lose.
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*/
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#ifdef ALTSEP
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if (strchr(prog, SEP) || strchr(prog, ALTSEP))
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#else
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if (strchr(prog, SEP))
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#endif
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strncpy(progpath, prog, MAXPATHLEN);
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else if (path) {
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while (1) {
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char *delim = strchr(path, DELIM);
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if (delim) {
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size_t len = delim - path;
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/* ensure we can't overwrite buffer */
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#if !defined(PYCC_GCC)
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len = min(MAXPATHLEN,len);
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#else
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len = MAXPATHLEN < len ? MAXPATHLEN : len;
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#endif
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strncpy(progpath, path, len);
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*(progpath + len) = '\0';
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}
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else
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strncpy(progpath, path, MAXPATHLEN);
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/* join() is safe for MAXPATHLEN+1 size buffer */
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join(progpath, prog);
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if (exists(progpath))
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break;
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if (!delim) {
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progpath[0] = '\0';
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break;
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}
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path = delim + 1;
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}
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}
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else
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progpath[0] = '\0';
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}
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static void
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calculate_path(void)
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{
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char argv0_path[MAXPATHLEN+1];
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char *buf;
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size_t bufsz;
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char *pythonhome = Py_GetPythonHome();
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char *envpath = getenv("PYTHONPATH");
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char zip_path[MAXPATHLEN+1];
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size_t len;
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get_progpath();
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/* progpath guaranteed \0 terminated in MAXPATH+1 bytes. */
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strcpy(argv0_path, progpath);
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reduce(argv0_path);
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if (pythonhome == NULL || *pythonhome == '\0') {
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if (search_for_prefix(argv0_path, LANDMARK))
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pythonhome = prefix;
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else
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pythonhome = NULL;
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}
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else
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strncpy(prefix, pythonhome, MAXPATHLEN);
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if (envpath && *envpath == '\0')
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envpath = NULL;
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/* Calculate zip archive path */
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strncpy(zip_path, progpath, MAXPATHLEN);
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zip_path[MAXPATHLEN] = '\0';
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len = strlen(zip_path);
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if (len > 4) {
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zip_path[len-3] = 'z'; /* change ending to "zip" */
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zip_path[len-2] = 'i';
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zip_path[len-1] = 'p';
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}
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else {
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zip_path[0] = 0;
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}
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/* We need to construct a path from the following parts.
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(1) the PYTHONPATH environment variable, if set;
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(2) the zip archive file path;
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(3) the PYTHONPATH config macro, with the leading "."
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of each component replaced with pythonhome, if set;
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(4) the directory containing the executable (argv0_path).
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The length calculation calculates #3 first.
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*/
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/* Calculate size of return buffer */
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if (pythonhome != NULL) {
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char *p;
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bufsz = 1;
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for (p = PYTHONPATH; *p; p++) {
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if (*p == DELIM)
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bufsz++; /* number of DELIM plus one */
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}
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bufsz *= strlen(pythonhome);
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}
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else
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bufsz = 0;
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bufsz += strlen(PYTHONPATH) + 1;
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bufsz += strlen(argv0_path) + 1;
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bufsz += strlen(zip_path) + 1;
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if (envpath != NULL)
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bufsz += strlen(envpath) + 1;
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module_search_path = buf = malloc(bufsz);
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if (buf == NULL) {
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/* We can't exit, so print a warning and limp along */
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fprintf(stderr, "Can't malloc dynamic PYTHONPATH.\n");
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if (envpath) {
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fprintf(stderr, "Using environment $PYTHONPATH.\n");
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module_search_path = envpath;
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}
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else {
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fprintf(stderr, "Using default static path.\n");
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module_search_path = PYTHONPATH;
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}
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return;
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}
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if (envpath) {
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strcpy(buf, envpath);
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buf = strchr(buf, '\0');
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*buf++ = DELIM;
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}
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if (zip_path[0]) {
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strcpy(buf, zip_path);
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buf = strchr(buf, '\0');
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*buf++ = DELIM;
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}
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if (pythonhome == NULL) {
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strcpy(buf, PYTHONPATH);
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buf = strchr(buf, '\0');
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}
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else {
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char *p = PYTHONPATH;
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char *q;
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size_t n;
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for (;;) {
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q = strchr(p, DELIM);
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if (q == NULL)
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n = strlen(p);
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else
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n = q-p;
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if (p[0] == '.' && is_sep(p[1])) {
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strcpy(buf, pythonhome);
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buf = strchr(buf, '\0');
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p++;
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n--;
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}
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strncpy(buf, p, n);
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buf += n;
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if (q == NULL)
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break;
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*buf++ = DELIM;
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p = q+1;
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}
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}
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if (argv0_path) {
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*buf++ = DELIM;
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strcpy(buf, argv0_path);
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buf = strchr(buf, '\0');
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}
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*buf = '\0';
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}
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/* External interface */
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char *
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Py_GetPath(void)
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{
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if (!module_search_path)
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calculate_path();
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return module_search_path;
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}
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char *
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Py_GetPrefix(void)
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{
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if (!module_search_path)
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calculate_path();
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return prefix;
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}
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char *
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Py_GetExecPrefix(void)
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{
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return Py_GetPrefix();
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}
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char *
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Py_GetProgramFullPath(void)
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{
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if (!module_search_path)
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calculate_path();
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return progpath;
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}
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