mirror of https://github.com/python/cpython
Completely revamped the way the default path is constructed.
Idea and first three implementation rounds due to Barry -- after that I spent another day on it, hopefully it's enough for now :-) (Wait for the checkin to Setup.in.)
This commit is contained in:
Guido van Rossum
parent
ec61b77216
commit
305e5d0d4f
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@ -34,9 +34,104 @@ PERFORMANCE OF THIS SOFTWARE.
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#include "Python.h"
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#include "osdefs.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <strings.h>
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#ifndef PYTHONPATH
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#define PYTHONPATH "/usr/local/lib/python"
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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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* Two directories must be found, the platform independent directory
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* (prefix), containing the common .py and .pyc files, and the
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* platform dependent directory (exec_prefix), containing the shared
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* library modules. Note that prefix and exec_prefix can be the same
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* directory, but for some installations, they are different.
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*
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* Py_GetPath() carries out separate searches for prefix and
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* exec_prefix. Each search tries a number of different locations
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* until a ``landmark'' file or directory is found. If no prefix or
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* exec_prefix is found, a warning message is issued and the
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* preprocessor defines PREFIX and EXEC_PREFIX are used (even though
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* they will not work); python carries on as best as is possible, but
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* most imports will fail.
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*
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* Before any searches are done, the location of the executable is
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* determined. If argv[0] has a slash in it (or more), this is it;
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* otherwise, it must have been invoked from the shell's path, so we
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* 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
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* environment variable), the original argv[0] string is used.
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*
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* Next, either the executable location is examined to see if it is a
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* symbolic link. If so, the link is chased (correctly interpreting a
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* relative pathname if one is found) and the directory of the link
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* target is used as instead.
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*
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* Finally, argv0_path is set to the directory containing the
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* executable (i.e. the last component is stripped).
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*
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* With argv0_path in hand, we perform a number of steps. The same
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* steps are performed for prefix and for exec_prefix, but with a
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* different landmark.
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*
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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
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* VPATH preprocessor variable (taking into account that its value is
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* almost, but not quite, what we need). If the landmark is found,
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* we're done.
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*
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* For the remaining steps, the prefix landmark will always be
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* lib/python$VERSION/string.py and the exec_prefix will always be
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* lib/python$VERSION/sharedmodules, where $VERSION is Python's
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* version number as supplied by the Makefile. Note that this means
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* that no more build directory checking is performed; if the first
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* two steps did not find the landmarks, the assumption is that python
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* is running from an installed setup.
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*
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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,
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* then it points to prefix and exec_prefix. $PYTHONHOME can be a
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* single directory, which is used for both, or the prefix and
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* exec_prefix directories separated by a colon.
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*
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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
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* common step to succeed. Note that if prefix and exec_prefix are
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* different, exec_prefix is more likely to be found; however if
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* exec_prefix is a subdirectory of prefix, both will be found.
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*
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* Step 4. Search the directories pointed to by the preprocessor
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* variables PREFIX and EXEC_PREFIX. These are supplied by the
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* Makefile but can be passed in as options to the configure script.
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*
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* Step 5. Search some `standard' directories, namely: /usr/local,
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* /usr, then finally /.
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*
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* That's it! Well, almost. Once we have determined prefix and
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* exec_prefix, the preprocesor variable PYTHONPATH is used to
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* construct a path. Each relative path on PYTHONPATH is prefixed
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* with prefix. Then the directory containing the shared library
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* modules is appended. The environment variable $PYTHONPATH is
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* inserted in front of it all. Finally, the prefix and exec_prefix
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* globals are tweaked so the reflect the values expected by other
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* code, by stripping the "lib/python$VERSION/..." stuff off. If
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* either points to the build directory, the globals are reset to the
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* corresponding preprocessor variables (so sys.prefix will reflect
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* the installation location, even though sys.path points into the
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* build directory). This seems to make more sense given that
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* currently the only known use of sys.prefix and sys.exec_prefix is
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* for the ILU installation process to find the installed Python tree. */
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#ifndef VERSION
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#define VERSION "1.5"
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#endif
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#ifndef VPATH
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#define VPATH "."
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#endif
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#ifndef PREFIX
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@ -47,51 +142,453 @@ PERFORMANCE OF THIS SOFTWARE.
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#define EXEC_PREFIX PREFIX
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#endif
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#ifndef PYTHONPATH
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/* I know this isn't K&R C, but the Makefile specifies it anyway */
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#define PYTHONPATH PREFIX "/lib/python" VERSION ":" \
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PREFIX "/lib/python" VERSION "/test" ":" \
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EXEC_PREFIX "/lib/python" VERSION "/sharedmodules"
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#endif
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/* This is called once from pythonrun to initialize sys.path. The
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environment variable PYTHONPATH is fetched and the default path
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appended. The default path may be passed to the preprocessor; if
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not, a hardcoded default is used, which only makes (some) sense on
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Unix. */
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#ifndef LANDMARK
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#define LANDMARK "string.py"
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#endif
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static char *std_dirs[] = {"/usr/local/", "/usr/", "/", NULL};
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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 *module_search_path = NULL;
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static char lib_python[20]; /* Dynamically set to "lib/python" VERSION */
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static void
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reduce(dir)
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char *dir;
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{
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int i = strlen(dir);
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while (i > 0 && dir[i] != SEP)
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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(filename)
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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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static void
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join(buffer, stuff)
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char *buffer;
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char *stuff;
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{
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int n, k;
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if (stuff[0] == SEP)
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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 && buffer[n-1] != SEP && 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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/* Make sure path ends in a slash.
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* Assume path is MAXPATHLEN+1 sized buffer.
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*/
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static void
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string_addsep(path)
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char *path;
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{
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int len = strlen(path);
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if (path[len-1] != SEP) {
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path[len] = SEP;
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if (len < MAXPATHLEN)
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len++;
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path[len] = '\0';
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}
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}
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/* Append a source string onto the destination string, watching for
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* buffer overruns. Assumes dest is MAXPATHLEN+1 sized buffer.
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*/
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static void
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string_append(dest, source)
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char *dest;
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char *source;
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{
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int dlen = strlen(dest);
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int slen = strlen(source);
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int len = dlen + slen;
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strncat(dest, source, MAXPATHLEN - dlen);
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if (len < MAXPATHLEN)
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len++;
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dest[len] = '\0';
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}
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static int
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search_for_prefix(argv0_path, home)
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char *argv0_path;
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char *home;
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{
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int i, n;
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char *vpath;
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/* Check VPATH to see if argv0_path is in the build directory.
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* Complication: the VPATH passed in is relative to the
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* Modules build directory and points to the Modules source
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* directory; we need it relative to the build tree and
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* pointing to the source tree. Solution: chop off a leading
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* ".." (but only if it's there -- it could be an absolute
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* path) and chop off the final component (assuming it's
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* "Modules").
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*/
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vpath = VPATH;
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if (vpath[0] == '.' && vpath[1] == '.' && vpath[2] == '/')
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vpath += 3;
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strcpy(prefix, argv0_path);
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join(prefix, vpath);
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reduce(prefix);
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join(prefix, "Lib");
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join(prefix, LANDMARK);
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if (exists(prefix))
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return -1;
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if (home) {
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/* Check $PYTHONHOME */
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char *delim;
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strcpy(prefix, home);
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delim = strchr(prefix, DELIM);
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if (delim)
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*delim = '\0';
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join(prefix, lib_python);
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join(prefix, LANDMARK);
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if (exists(prefix))
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return 1;
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}
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/* Search from argv0_path, until root is found */
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strcpy(prefix, argv0_path);
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do {
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n = strlen(prefix);
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join(prefix, lib_python);
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join(prefix, LANDMARK);
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if (exists(prefix))
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return 1;
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prefix[n] = '\0';
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reduce(prefix);
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} while (prefix[0]);
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/* Look at configure's PREFIX */
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strcpy(prefix, PREFIX);
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join(prefix, lib_python);
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join(prefix, LANDMARK);
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if (exists(prefix))
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return 1;
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/* Look at `standard' directories */
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for (i = 0; std_dirs[i]; i++) {
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strcpy(prefix, std_dirs[i]);
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join(prefix, lib_python);
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join(prefix, LANDMARK);
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if (exists(prefix))
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return 1;
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}
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return 0;
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}
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static int
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search_for_exec_prefix(argv0_path, home)
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char *argv0_path;
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char *home;
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{
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int i, n;
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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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join(exec_prefix, "Modules/Setup");
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if (exists(exec_prefix)) {
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reduce(exec_prefix);
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return -1;
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}
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if (home) {
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/* Check $PYTHONHOME */
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char *delim;
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delim = strchr(home, DELIM);
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if (delim)
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strcpy(exec_prefix, delim+1);
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else
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strcpy(exec_prefix, home);
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join(exec_prefix, lib_python);
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join(exec_prefix, "sharedmodules");
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if (exists(exec_prefix))
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return 1;
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}
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/* Search from argv0_path, until root is found */
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strcpy(exec_prefix, argv0_path);
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do {
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n = strlen(exec_prefix);
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join(exec_prefix, lib_python);
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join(exec_prefix, "sharedmodules");
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if (exists(exec_prefix))
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return 1;
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exec_prefix[n] = '\0';
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reduce(exec_prefix);
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} while (exec_prefix[0]);
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/* Look at configure's EXEC_PREFIX */
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strcpy(exec_prefix, EXEC_PREFIX);
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join(exec_prefix, lib_python);
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join(exec_prefix, "sharedmodules");
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if (exists(exec_prefix))
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return 1;
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/* Look at `standard' directories */
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for (i = 0; std_dirs[i]; i++) {
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strcpy(exec_prefix, std_dirs[i]);
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join(exec_prefix, lib_python);
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join(exec_prefix, "sharedmodules");
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if (exists(exec_prefix))
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return 1;
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}
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return 0;
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}
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static void
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calculate_path()
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{
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extern char *Py_GetProgramName();
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char delimiter[2] = {DELIM, '\0'};
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char separator[2] = {SEP, '\0'};
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char *pythonpath = PYTHONPATH;
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char *rtpypath = getenv("PYTHONPATH");
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char *home = getenv("PYTHONHOME");
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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 progpath[MAXPATHLEN+1];
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int pfound, efound; /* 1 if found; -1 if found build directory */
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char *buf;
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int bufsz;
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int prefixsz;
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char *defpath = pythonpath;
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/* Initialize this dynamically for K&R C */
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sprintf(lib_python, "lib/python%s", VERSION);
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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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if (strchr(prog, SEP))
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strcpy(progpath, prog);
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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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int len = delim - path;
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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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strcpy(progpath, path);
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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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strcpy(argv0_path, progpath);
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#if HAVE_READLINK
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{
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char tmpbuffer[MAXPATHLEN+1];
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int linklen = readlink(progpath, tmpbuffer, MAXPATHLEN);
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if (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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strcpy(argv0_path, tmpbuffer);
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else {
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/* Interpret relative to progpath */
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reduce(argv0_path);
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join(argv0_path, tmpbuffer);
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}
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}
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}
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#endif /* HAVE_READLINK */
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reduce(argv0_path);
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if (!(pfound = search_for_prefix(argv0_path, home))) {
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fprintf(stderr,
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"Could not find platform independent libraries <prefix>\n");
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strcpy(prefix, PREFIX);
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join(prefix, lib_python);
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}
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else
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reduce(prefix);
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if (!(efound = search_for_exec_prefix(argv0_path, home))) {
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fprintf(stderr,
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"Could not find platform dependent libraries <exec_prefix>\n");
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strcpy(exec_prefix, EXEC_PREFIX);
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join(exec_prefix, "lib/sharedmodules");
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}
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/* If we found EXEC_PREFIX do *not* reduce it! (Yet.) */
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if (!pfound || !efound)
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fprintf(stderr,
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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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*/
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bufsz = 0;
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if (rtpypath)
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bufsz += strlen(rtpypath) + 1;
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prefixsz = strlen(prefix) + 1;
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while (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 += prefixsz;
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if (delim)
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bufsz += delim - defpath + 1;
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else {
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bufsz += strlen(defpath) + 1;
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break;
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}
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defpath = delim + 1;
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}
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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 = 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, "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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}
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else {
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/* Run-time value of $PYTHONPATH goes first */
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if (rtpypath) {
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strcpy(buf, rtpypath);
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strcat(buf, delimiter);
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}
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/* Next goes merge of compile-time $PYTHONPATH with
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* dynamically located prefix.
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*/
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defpath = pythonpath;
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while (1) {
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char *delim = strchr(defpath, DELIM);
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if (defpath[0] != SEP) {
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strcat(buf, prefix);
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strcat(buf, separator);
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}
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||||
|
||||
if (delim) {
|
||||
int len = delim - defpath + 1;
|
||||
int end = strlen(buf) + len;
|
||||
strncat(buf, defpath, len);
|
||||
*(buf + end) = '\0';
|
||||
}
|
||||
else {
|
||||
strcat(buf, defpath);
|
||||
break;
|
||||
}
|
||||
defpath = delim + 1;
|
||||
}
|
||||
strcat(buf, delimiter);
|
||||
|
||||
/* Finally, on goes the directory for dynamic-load modules */
|
||||
strcat(buf, exec_prefix);
|
||||
|
||||
/* And publish the results */
|
||||
module_search_path = buf;
|
||||
}
|
||||
|
||||
/* Reduce prefix and exec_prefix to their essence,
|
||||
* e.g. /usr/local/lib/python1.5 is reduced to /usr/local.
|
||||
* If we're loading relative to the build directory,
|
||||
* return the compiled-in defaults instead.
|
||||
*/
|
||||
if (pfound > 0) {
|
||||
reduce(prefix);
|
||||
reduce(prefix);
|
||||
}
|
||||
else
|
||||
strcpy(prefix, PREFIX);
|
||||
|
||||
if (efound > 0) {
|
||||
reduce(exec_prefix);
|
||||
reduce(exec_prefix);
|
||||
reduce(exec_prefix);
|
||||
}
|
||||
else
|
||||
strcpy(exec_prefix, EXEC_PREFIX);
|
||||
}
|
||||
|
||||
|
||||
/* External interface */
|
||||
|
||||
char *
|
||||
Py_GetPath()
|
||||
{
|
||||
char *path = getenv("PYTHONPATH");
|
||||
char *defpath = PYTHONPATH;
|
||||
static char *buf = NULL;
|
||||
char *p;
|
||||
int n;
|
||||
|
||||
if (path == NULL)
|
||||
path = "";
|
||||
n = strlen(path) + strlen(defpath) + 2;
|
||||
if (buf != NULL) {
|
||||
free(buf);
|
||||
buf = NULL;
|
||||
}
|
||||
buf = malloc(n);
|
||||
if (buf == NULL)
|
||||
Py_FatalError("not enough memory to copy module search path");
|
||||
strcpy(buf, path);
|
||||
p = buf + strlen(buf);
|
||||
if (p != buf)
|
||||
*p++ = DELIM;
|
||||
strcpy(p, defpath);
|
||||
return buf;
|
||||
if (!module_search_path)
|
||||
calculate_path();
|
||||
return module_search_path;
|
||||
}
|
||||
|
||||
|
||||
/* Similar for Makefile variables $prefix and $exec_prefix */
|
||||
|
||||
char *
|
||||
Py_GetPrefix()
|
||||
{
|
||||
return PREFIX;
|
||||
if (!module_search_path)
|
||||
calculate_path();
|
||||
return prefix;
|
||||
}
|
||||
|
||||
char *
|
||||
Py_GetExecPrefix()
|
||||
{
|
||||
return EXEC_PREFIX;
|
||||
if (!module_search_path)
|
||||
calculate_path();
|
||||
return exec_prefix;
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue