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/* Return the initial module search path. */
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#include <mach-o/dyld.h>
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/* Search in some common locations for the associated Python libraries.
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* Two directories must be found, the platform independent directory
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* (prefix), containing the common .py and .pyc files, and the platform
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* dependent directory (exec_prefix), containing the shared library
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* modules. Note that prefix and exec_prefix can be the same directory,
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* but for some installations, they are different.
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* Py_GetPath() carries out separate searches for prefix and exec_prefix.
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* Each search tries a number of different locations until a ``landmark''
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* file or directory is found. If no prefix or exec_prefix is found, a
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* warning message is issued and the preprocessor defined PREFIX and
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* EXEC_PREFIX are used (even though they will not work); python carries on
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* as best as is possible, but most imports will fail.
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* Before any searches are done, the location of the executable is
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* determined. If argv[0] has one or more slashes in it, it is used
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* unchanged. Otherwise, it must have been invoked from the shell's path,
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* so we search $PATH for the named executable and use that. If the
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* executable was not found on $PATH (or there was no $PATH environment
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* variable), the original argv[0] string is used.
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* Next, the executable location is examined to see if it is a symbolic
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* link. If so, the link is chased (correctly interpreting a relative
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* pathname if one is found) and the directory of the link target is used.
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* Finally, argv0_path is set to the directory containing the executable
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* (i.e. the last component is stripped).
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* With argv0_path in hand, we perform a number of steps. The same steps
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* are performed for prefix and for exec_prefix, but with a different
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* Step 1. Are we running python out of the build directory? This is
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* checked by looking for a different kind of landmark relative to
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* argv0_path. For prefix, the landmark's path is derived from the VPATH
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* preprocessor variable (taking into account that its value is almost, but
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* not quite, what we need). For exec_prefix, the landmark is
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* Modules/Setup. If the landmark is found, we're done.
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* For the remaining steps, the prefix landmark will always be
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* lib/python$VERSION/os.py and the exec_prefix will always be
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* lib/python$VERSION/lib-dynload, where $VERSION is Python's version
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* number as supplied by the Makefile. Note that this means that no more
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* build directory checking is performed; if the first step did not find
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* the landmarks, the assumption is that python is running from an
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* Step 2. See if the $PYTHONHOME environment variable points to the
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* installed location of the Python libraries. If $PYTHONHOME is set, then
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* it points to prefix and exec_prefix. $PYTHONHOME can be a single
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* directory, which is used for both, or the prefix and exec_prefix
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* directories separated by a colon.
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* Step 3. Try to find prefix and exec_prefix relative to argv0_path,
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* backtracking up the path until it is exhausted. This is the most common
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* step to succeed. Note that if prefix and exec_prefix are different,
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* exec_prefix is more likely to be found; however if exec_prefix is a
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* subdirectory of prefix, both will be found.
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* Step 4. Search the directories pointed to by the preprocessor variables
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* PREFIX and EXEC_PREFIX. These are supplied by the Makefile but can be
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* passed in as options to the configure script.
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* Well, almost. Once we have determined prefix and exec_prefix, the
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* preprocessor variable PYTHONPATH is used to construct a path. Each
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* relative path on PYTHONPATH is prefixed with prefix. Then the directory
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* containing the shared library modules is appended. The environment
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* variable $PYTHONPATH is inserted in front of it all. Finally, the
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* prefix and exec_prefix globals are tweaked so they reflect the values
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* expected by other code, by stripping the "lib/python$VERSION/..." stuff
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* off. If either points to the build directory, the globals are reset to
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* the corresponding preprocessor variables (so sys.prefix will reflect the
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* installation location, even though sys.path points into the build
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* directory). This seems to make more sense given that currently the only
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* known use of sys.prefix and sys.exec_prefix is for the ILU installation
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* process to find the installed Python tree.
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#define VERSION "2.1"
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# define PREFIX "/usr/local"
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#define EXEC_PREFIX PREFIX
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#define PYTHONPATH PREFIX "/lib/python" VERSION ":" \
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EXEC_PREFIX "/lib/python" VERSION "/lib-dynload"
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#define LANDMARK "os.py"
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static char prefix[MAXPATHLEN+1];
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static char exec_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 char lib_python[] = "lib/python" VERSION;
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size_t i = strlen(dir);
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while (i > 0 && dir[i] != SEP)
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isfile(char *filename) /* Is file, not directory */
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if (stat(filename, &buf) != 0)
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if (!S_ISREG(buf.st_mode))
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ismodule(char *filename) /* Is module -- check for .pyc/.pyo too */
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if (isfile(filename))
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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 (isfile(filename))
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isxfile(char *filename) /* Is executable file */
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if (stat(filename, &buf) != 0)
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if (!S_ISREG(buf.st_mode))
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if ((buf.st_mode & 0111) == 0)
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isdir(char *filename) /* Is directory */
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if (stat(filename, &buf) != 0)
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if (!S_ISDIR(buf.st_mode))
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/* Add a path component, by appending stuff to buffer.
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buffer must have at least MAXPATHLEN + 1 bytes allocated, and contain a
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NUL-terminated string with no more than MAXPATHLEN characters (not counting
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the trailing NUL). It's a fatal error if it contains a string longer than
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that (callers must be careful!). If these requirements are met, it's
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guaranteed that buffer will still be a NUL-terminated string with no more
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than MAXPATHLEN characters at exit. If stuff is too long, only as much of
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stuff as fits will be appended.
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joinpath(char *buffer, char *stuff)
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if (n > 0 && buffer[n-1] != SEP && n < MAXPATHLEN)
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Py_FatalError("buffer overflow in getpath.c's joinpath()");
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if (n + k > MAXPATHLEN)
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strncpy(buffer+n, stuff, k);
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/* copy_absolute requires that path be allocated at least
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MAXPATHLEN + 1 bytes and that p be no more than MAXPATHLEN bytes. */
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copy_absolute(char *path, char *p)
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getcwd(path, MAXPATHLEN);
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if (p[0] == '.' && p[1] == SEP)
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/* absolutize() requires that path be allocated at least MAXPATHLEN+1 bytes. */
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absolutize(char *path)
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char buffer[MAXPATHLEN + 1];
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copy_absolute(buffer, path);
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strcpy(path, buffer);
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/* search_for_prefix requires that argv0_path be no more than MAXPATHLEN
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search_for_prefix(char *argv0_path, char *home)
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/* If PYTHONHOME is set, we believe it unconditionally */
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strncpy(prefix, home, MAXPATHLEN);
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delim = strchr(prefix, DELIM);
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joinpath(prefix, lib_python);
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joinpath(prefix, LANDMARK);
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/* Check to see if argv[0] is in the build directory */
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strcpy(prefix, argv0_path);
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joinpath(prefix, "Modules/Setup");
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if (isfile(prefix)) {
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/* Check VPATH to see if argv0_path is in the build directory. */
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strcpy(prefix, argv0_path);
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joinpath(prefix, vpath);
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joinpath(prefix, "Lib");
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joinpath(prefix, LANDMARK);
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if (ismodule(prefix))
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/* Search from argv0_path, until root is found */
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copy_absolute(prefix, argv0_path);
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joinpath(prefix, lib_python);
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joinpath(prefix, LANDMARK);
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if (ismodule(prefix))
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/* Look at configure's PREFIX */
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strncpy(prefix, PREFIX, MAXPATHLEN);
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joinpath(prefix, lib_python);
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joinpath(prefix, LANDMARK);
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if (ismodule(prefix))
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/* search_for_exec_prefix requires that argv0_path be no more than
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MAXPATHLEN bytes long.
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search_for_exec_prefix(char *argv0_path, char *home)
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/* If PYTHONHOME is set, we believe it unconditionally */
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delim = strchr(home, DELIM);
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strncpy(exec_prefix, delim+1, MAXPATHLEN);
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strncpy(exec_prefix, home, MAXPATHLEN);
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joinpath(exec_prefix, lib_python);
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joinpath(exec_prefix, "lib-dynload");
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/* Check to see if argv[0] is in the build directory */
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strcpy(exec_prefix, argv0_path);
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joinpath(exec_prefix, "Modules/Setup");
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if (isfile(exec_prefix)) {
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/* Search from argv0_path, until root is found */
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copy_absolute(exec_prefix, argv0_path);
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n = strlen(exec_prefix);
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joinpath(exec_prefix, lib_python);
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joinpath(exec_prefix, "lib-dynload");
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if (isdir(exec_prefix))
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exec_prefix[n] = '\0';
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} while (exec_prefix[0]);
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/* Look at configure's EXEC_PREFIX */
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strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
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joinpath(exec_prefix, lib_python);
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joinpath(exec_prefix, "lib-dynload");
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if (isdir(exec_prefix))
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extern char *Py_GetProgramName(void);
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static char delimiter[2] = {DELIM, '\0'};
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static char separator[2] = {SEP, '\0'};
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char *pythonpath = PYTHONPATH;
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char *rtpypath = Py_GETENV("PYTHONPATH");
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char *home = Py_GetPythonHome();
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char *path = getenv("PATH");
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char *prog = Py_GetProgramName();
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char argv0_path[MAXPATHLEN+1];
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char zip_path[MAXPATHLEN+1];
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int pfound, efound; /* 1 if found; -1 if found build directory */
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char *defpath = pythonpath;
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#ifdef WITH_NEXT_FRAMEWORK
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NSModule pythonModule;
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#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_4
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uint32_t nsexeclength = MAXPATHLEN;
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unsigned long nsexeclength = MAXPATHLEN;
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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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if (strchr(prog, SEP))
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strncpy(progpath, prog, MAXPATHLEN);
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/* On Mac OS X, if a script uses an interpreter of the form
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* "#!/opt/python2.3/bin/python", the kernel only passes "python"
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* as argv[0], which falls through to the $PATH search below.
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* If /opt/python2.3/bin isn't in your path, or is near the end,
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* this algorithm may incorrectly find /usr/bin/python. To work
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* around this, we can use _NSGetExecutablePath to get a better
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* hint of what the intended interpreter was, although this
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* will fail if a relative path was used. but in that case,
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* absolutize() should help us out below
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else if(0 == _NSGetExecutablePath(progpath, &nsexeclength) && progpath[0] == SEP)
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#endif /* __APPLE__ */
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char *delim = strchr(path, DELIM);
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size_t len = delim - path;
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if (len > MAXPATHLEN)
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strncpy(progpath, path, len);
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*(progpath + len) = '\0';
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strncpy(progpath, path, MAXPATHLEN);
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joinpath(progpath, prog);
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if (isxfile(progpath))
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if (progpath[0] != SEP)
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absolutize(progpath);
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strncpy(argv0_path, progpath, MAXPATHLEN);
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argv0_path[MAXPATHLEN] = '\0';
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#ifdef WITH_NEXT_FRAMEWORK
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/* On Mac OS X we have a special case if we're running from a framework.
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** This is because the python home should be set relative to the library,
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** which is in the framework, not relative to the executable, which may
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** be outside of the framework. Except when we're in the build directory...
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pythonModule = NSModuleForSymbol(NSLookupAndBindSymbol("_Py_Initialize"));
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/* Use dylib functions to find out where the framework was loaded from */
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buf = (char *)NSLibraryNameForModule(pythonModule);
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/* We're in a framework. */
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/* See if we might be in the build directory. The framework in the
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** build directory is incomplete, it only has the .dylib and a few
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** needed symlinks, it doesn't have the Lib directories and such.
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** If we're running with the framework from the build directory we must
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** be running the interpreter in the build directory, so we use the
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** build-directory-specific logic to find Lib and such.
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strncpy(argv0_path, buf, MAXPATHLEN);
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joinpath(argv0_path, lib_python);
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joinpath(argv0_path, LANDMARK);
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if (!ismodule(argv0_path)) {
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/* We are in the build directory so use the name of the
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executable - we know that the absolute path is passed */
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strncpy(argv0_path, prog, MAXPATHLEN);
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/* Use the location of the library as the progpath */
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strncpy(argv0_path, buf, MAXPATHLEN);
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char tmpbuffer[MAXPATHLEN+1];
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int linklen = readlink(progpath, tmpbuffer, MAXPATHLEN);
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while (linklen != -1) {
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/* It's not null terminated! */
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tmpbuffer[linklen] = '\0';
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if (tmpbuffer[0] == SEP)
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/* tmpbuffer should never be longer than MAXPATHLEN,
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but extra check does not hurt */
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strncpy(argv0_path, tmpbuffer, MAXPATHLEN);
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/* Interpret relative to progpath */
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joinpath(argv0_path, tmpbuffer);
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linklen = readlink(argv0_path, tmpbuffer, MAXPATHLEN);
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#endif /* HAVE_READLINK */
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/* At this point, argv0_path is guaranteed to be less than
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MAXPATHLEN bytes long.
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if (!(pfound = search_for_prefix(argv0_path, home))) {
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"Could not find platform independent libraries <prefix>\n");
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strncpy(prefix, PREFIX, MAXPATHLEN);
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joinpath(prefix, lib_python);
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strncpy(zip_path, prefix, MAXPATHLEN);
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zip_path[MAXPATHLEN] = '\0';
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if (pfound > 0) { /* Use the reduced prefix returned by Py_GetPrefix() */
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strncpy(zip_path, PREFIX, MAXPATHLEN);
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joinpath(zip_path, "lib/python00.zip");
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bufsz = strlen(zip_path); /* Replace "00" with version */
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zip_path[bufsz - 6] = VERSION[0];
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zip_path[bufsz - 5] = VERSION[2];
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if (!(efound = search_for_exec_prefix(argv0_path, home))) {
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"Could not find platform dependent libraries <exec_prefix>\n");
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strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
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joinpath(exec_prefix, "lib/lib-dynload");
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/* If we found EXEC_PREFIX do *not* reduce it! (Yet.) */
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if ((!pfound || !efound) && !Py_FrozenFlag)
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"Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]\n");
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/* Calculate size of return buffer.
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bufsz += strlen(rtpypath) + 1;
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prefixsz = strlen(prefix) + 1;
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char *delim = strchr(defpath, DELIM);
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if (defpath[0] != SEP)
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/* Paths are relative to prefix */
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bufsz += delim - defpath + 1;
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bufsz += strlen(defpath) + 1;
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bufsz += strlen(zip_path) + 1;
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bufsz += strlen(exec_prefix) + 1;
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/* This is the only malloc call in this file */
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buf = (char *)PyMem_Malloc(bufsz);
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/* We can't exit, so print a warning and limp along */
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fprintf(stderr, "Not enough memory for dynamic PYTHONPATH.\n");
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fprintf(stderr, "Using default static PYTHONPATH.\n");
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module_search_path = PYTHONPATH;
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/* Run-time value of $PYTHONPATH goes first */
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strcpy(buf, rtpypath);
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strcat(buf, delimiter);
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/* Next is the default zip path */
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strcat(buf, zip_path);
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strcat(buf, delimiter);
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/* Next goes merge of compile-time $PYTHONPATH with
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* dynamically located prefix.
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defpath = pythonpath;
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char *delim = strchr(defpath, DELIM);
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if (defpath[0] != SEP) {
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strcat(buf, separator);
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size_t len = delim - defpath + 1;
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size_t end = strlen(buf) + len;
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strncat(buf, defpath, len);
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strcat(buf, defpath);
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strcat(buf, delimiter);
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/* Finally, on goes the directory for dynamic-load modules */
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strcat(buf, exec_prefix);
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/* And publish the results */
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module_search_path = buf;
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/* Reduce prefix and exec_prefix to their essence,
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* e.g. /usr/local/lib/python1.5 is reduced to /usr/local.
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* If we're loading relative to the build directory,
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* return the compiled-in defaults instead.
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/* The prefix is the root directory, but reduce() chopped
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strcpy(prefix, separator);
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strncpy(prefix, PREFIX, MAXPATHLEN);
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strcpy(exec_prefix, separator);
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strncpy(exec_prefix, EXEC_PREFIX, MAXPATHLEN);
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/* External interface */
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if (!module_search_path)
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return module_search_path;
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if (!module_search_path)
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Py_GetExecPrefix(void)
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if (!module_search_path)
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Py_GetProgramFullPath(void)
685
if (!module_search_path)
added
removed
Modules/getpath.c
