Jim Ahlstrom's contributions for DOS, OS/2, WIN3.1.
diff --git a/PC/getpathp.c b/PC/getpathp.c
new file mode 100644
index 0000000..b7d903b
--- /dev/null
+++ b/PC/getpathp.c
@@ -0,0 +1,294 @@
+/***********************************************************
+Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
+The Netherlands.
+
+ All Rights Reserved
+
+Permission to use, copy, modify, and distribute this software and its
+documentation for any purpose and without fee is hereby granted,
+provided that the above copyright notice appear in all copies and that
+both that copyright notice and this permission notice appear in
+supporting documentation, and that the names of Stichting Mathematisch
+Centrum or CWI or Corporation for National Research Initiatives or
+CNRI not be used in advertising or publicity pertaining to
+distribution of the software without specific, written prior
+permission.
+
+While CWI is the initial source for this software, a modified version
+is made available by the Corporation for National Research Initiatives
+(CNRI) at the Internet address ftp://ftp.python.org.
+
+STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
+CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
+DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.
+
+******************************************************************/
+
+/* Return the initial module search path. */
+/* Used by DOS, OS/2, Windows 3.1. Works on NT too. */
+
+#include "Python.h"
+#include "osdefs.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <string.h>
+
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif /* HAVE_UNISTD_H */
+
+/* Search in some common locations for the associated Python libraries.
+ *
+ * This version always returns "" for both prefix and exec_prefix.
+ *
+ * Py_GetPath() tries to return a sensible Python module search path.
+ *
+ * First, we look to see if the executable is in a subdirectory of
+ * the Python build directory. We calculate the full path of the
+ * directory containing the executable as progpath. We work backwards
+ * along progpath and look for $dir/Modules/Setup.in, a distinctive
+ * landmark. If found, we use $dir/Lib as $root. The returned
+ * Python path is the compiled #define PYTHONPATH with all the initial
+ * "./lib" replaced by $root.
+ *
+ * Otherwise, if there is a PYTHONPATH environment variable, we return that.
+ *
+ * Otherwise we try to find $progpath/lib/string.py, and if found, then
+ * root is $progpath/lib, and we return Python path as compiled PYTHONPATH
+ * with all "./lib" replaced by $root (as above).
+ *
+ */
+
+#ifndef LANDMARK
+#define LANDMARK "Modules\\Setup.in"
+#endif
+
+static char prefix[MAXPATHLEN+1];
+static char progpath[MAXPATHLEN+1];
+static char *module_search_path = NULL;
+
+static int
+is_sep(ch) /* determine if "ch" is a separator character */
+ char ch;
+{
+#ifdef ALTSEP
+ return ch == SEP || ch == ALTSEP;
+#else
+ return ch == SEP;
+#endif
+}
+
+static void
+reduce(dir)
+ char *dir;
+{
+ int i = strlen(dir);
+ while (i > 0 && !is_sep(dir[i]))
+ --i;
+ dir[i] = '\0';
+}
+
+
+static int
+exists(filename)
+ char *filename;
+{
+ struct stat buf;
+ return stat(filename, &buf) == 0;
+}
+
+
+static void
+join(buffer, stuff)
+ char *buffer;
+ char *stuff;
+{
+ int n, k;
+ if (is_sep(stuff[0]))
+ n = 0;
+ else {
+ n = strlen(buffer);
+ if (n > 0 && !is_sep(buffer[n-1]) && n < MAXPATHLEN)
+ buffer[n++] = SEP;
+ }
+ k = strlen(stuff);
+ if (n + k > MAXPATHLEN)
+ k = MAXPATHLEN - n;
+ strncpy(buffer+n, stuff, k);
+ buffer[n+k] = '\0';
+}
+
+
+static int
+search_for_prefix(argv0_path, landmark)
+ char *argv0_path;
+ char *landmark;
+{
+ int n;
+
+ /* Search from argv0_path, until root is found */
+ strcpy(prefix, argv0_path);
+ do {
+ n = strlen(prefix);
+ join(prefix, landmark);
+ if (exists(prefix))
+ return 1;
+ prefix[n] = '\0';
+ reduce(prefix);
+ } while (prefix[0]);
+ return 0;
+}
+
+static void
+get_progpath()
+{
+#ifdef MS_WIN32
+#include <windows.h>
+ if (!GetModuleFileName(NULL, progpath, MAXPATHLEN))
+ progpath[0] = '\0'; /* failure */
+#else
+ extern char *Py_GetProgramName();
+ char *path = getenv("PATH");
+ char *prog = Py_GetProgramName();
+
+ /* If there is no slash in the argv0 path, then we have to
+ * assume python is on the user's $PATH, since there's no
+ * other way to find a directory to start the search from. If
+ * $PATH isn't exported, you lose.
+ */
+#ifdef ALTSEP
+ if (strchr(prog, SEP) || strchr(prog, ALTSEP))
+#else
+ if (strchr(prog, SEP))
+#endif
+ strcpy(progpath, prog);
+ else if (path) {
+ while (1) {
+ char *delim = strchr(path, DELIM);
+
+ if (delim) {
+ int len = delim - path;
+ strncpy(progpath, path, len);
+ *(progpath + len) = '\0';
+ }
+ else
+ strcpy(progpath, path);
+
+ join(progpath, prog);
+ if (exists(progpath))
+ break;
+
+ if (!delim) {
+ progpath[0] = '\0';
+ break;
+ }
+ path = delim + 1;
+ }
+ }
+ else
+ progpath[0] = '\0';
+#endif
+}
+
+static void
+calculate_path()
+{
+ char ch, *pt, *pt2;
+ char argv0_path[MAXPATHLEN+1];
+ char *buf;
+ int bufsz;
+
+ get_progpath();
+ strcpy(argv0_path, progpath);
+ reduce(argv0_path);
+
+ if (search_for_prefix(argv0_path, LANDMARK)) {
+ reduce(prefix);
+ reduce(prefix);
+ join(prefix, "lib");
+ }
+ else if ((module_search_path = getenv("PYTHONPATH")) != 0) {
+ return; /* if PYTHONPATH environment variable exists, we are done */
+ }
+ else { /* Try the executable_directory/lib */
+ strcpy(prefix, progpath);
+ reduce(prefix);
+ join(prefix, "lib");
+ join(prefix, "string.py"); /* Look for lib/string.py */
+ if (exists(prefix)) {
+ reduce(prefix);
+ }
+ else { /* No module search path!!! */
+ module_search_path = PYTHONPATH;
+ return;
+ }
+ }
+
+
+ /* If we get here, we need to return a path equal to the compiled
+ PYTHONPATH with ".\lib" replaced by our "prefix" directory */
+
+ bufsz = 1; /* Calculate size of return buffer. */
+ for (pt = PYTHONPATH; *pt; pt++)
+ if (*pt == DELIM)
+ bufsz++; /* number of DELIM plus one */
+ bufsz *= strlen(PYTHONPATH) + strlen(prefix); /* high estimate */
+
+ module_search_path = buf = malloc(bufsz);
+
+ if (buf == NULL) {
+ /* We can't exit, so print a warning and limp along */
+ fprintf(stderr, "Not enough memory for dynamic PYTHONPATH.\n");
+ fprintf(stderr, "Using default static PYTHONPATH.\n");
+ module_search_path = PYTHONPATH;
+ return;
+ }
+ for (pt = PYTHONPATH; *pt; pt++) {
+ if (!strncmp(pt, ".\\lib", 5) &&
+ ((ch = *(pt + 5)) == '\\' || ch == DELIM || !ch)){
+ pt += 4;
+ for (pt2 = prefix; *pt2; pt2++)
+ *buf++ = *pt2;
+ }
+ else
+ *buf++ = *pt;
+ }
+ *buf = '\0';
+}
+
+
+/* External interface */
+
+char *
+Py_GetPath()
+{
+ if (!module_search_path)
+ calculate_path();
+ return module_search_path;
+}
+
+char *
+Py_GetPrefix()
+{
+ return "";
+}
+
+char *
+Py_GetExecPrefix()
+{
+ return "";
+}
+
+char *
+Py_GetProgramFullPath() /* Full path to Python executable */
+{
+ if (!module_search_path)
+ calculate_path();
+ return progpath;
+}