Be more rigorous about making pathnames absolute, to address SF bug

#424002.

Refactor init_path_from_argv0() and rename to copy_absolute(); add
absolutize() which does the same in-place.

Clean up whitespace (leading tabs -> spaces, delete trailing
spaces/tabs).

Modules/getpath.c

@@ -213,28 +213,33 @@ joinpath(char *buffer, char *stuff)
     buffer[n+k] = '\0';
 }
 
-/* init_path_from_argv0 requires that path be allocated at least
-   MAXPATHLEN + 1 bytes and that argv0_path be no more than MAXPATHLEN
-   bytes. 
-*/
+/* copy_absolute requires that path be allocated at least
+   MAXPATHLEN + 1 bytes and that p be no more than MAXPATHLEN bytes. */
 static void
-init_path_from_argv0(char *path, char *argv0_path)
+copy_absolute(char *path, char *p)
 {
-    if (argv0_path[0] == '/')
-	strcpy(path, argv0_path);
-    else if (argv0_path[0] == '.') {
-	getcwd(path, MAXPATHLEN);
-	if (argv0_path[1] == '/') 
-	    joinpath(path, argv0_path + 2);
-	else
-	    joinpath(path, argv0_path);
-    }
+    if (p[0] == SEP)
+        strcpy(path, p);
     else {
         getcwd(path, MAXPATHLEN);
-	joinpath(path, argv0_path);
+        if (p[0] == '.' && p[1] == SEP)
+            p += 2;
+        joinpath(path, p);
     }
 }
 
+/* absolutize() requires that path be allocated at least MAXPATHLEN+1 bytes. */
+static void
+absolutize(char *path)
+{
+    char buffer[MAXPATHLEN + 1];
+
+    if (path[0] == SEP)
+        return;
+    copy_absolute(buffer, path);
+    strcpy(path, buffer);
+}
+
 /* search_for_prefix requires that argv0_path be no more than MAXPATHLEN
    bytes long.
 */
@@ -271,7 +276,7 @@ search_for_prefix(char *argv0_path, char *home)
     }
 
     /* Search from argv0_path, until root is found */
-    init_path_from_argv0(prefix, argv0_path);
+    copy_absolute(prefix, argv0_path);
     do {
         n = strlen(prefix);
         joinpath(prefix, lib_python);
@@ -324,7 +329,7 @@ search_for_exec_prefix(char *argv0_path, char *home)
     }
 
     /* Search from argv0_path, until root is found */
-    init_path_from_argv0(exec_prefix, argv0_path);
+    copy_absolute(exec_prefix, argv0_path);
     do {
         n = strlen(exec_prefix);
         joinpath(exec_prefix, lib_python);
@@ -409,20 +414,18 @@ calculate_path(void)
         if (strchr(prog, SEP))
             strncpy(progpath, prog, MAXPATHLEN);
         else if (path) {
-	    int bufspace = MAXPATHLEN;
             while (1) {
                 char *delim = strchr(path, DELIM);
 
                 if (delim) {
                     size_t len = delim - path;
-		    if (len > bufspace)
-			len = bufspace;
+                    if (len > MAXPATHLEN)
+                        len = MAXPATHLEN;
                     strncpy(progpath, path, len);
                     *(progpath + len) = '\0';
-		    bufspace -= len;
                 }
                 else
-                    strncpy(progpath, path, bufspace);
+                    strncpy(progpath, path, MAXPATHLEN);
 
                 joinpath(progpath, prog);
                 if (isxfile(progpath))
@@ -437,6 +440,8 @@ calculate_path(void)
         }
         else
             progpath[0] = '\0';
+        if (progpath[0] != SEP)
+            absolutize(progpath);
 #ifdef WITH_NEXT_FRAMEWORK
     }
 #endif