2002-07-17  Alan Modra  <amodra@bigpond.net.au>

	* prefix.c (update_path): Strip ".." components when prior dir
	doesn't exist.  Pass correct var to UPDATE_PATH_HOST_CANONICALIZE.
	
--- gcc-3.2/gcc/prefix.c.strip-dotdot	2001-10-11 05:15:55.000000000 +0200
+++ gcc-3.2/gcc/prefix.c	2002-08-17 09:37:01.000000000 +0200
@@ -251,7 +252,7 @@ update_path (path, key)
   const char *path;
   const char *key;
 {
-  char *result;
+  char *result, *p;
 
   if (! strncmp (path, std_prefix, strlen (std_prefix)) && key != 0)
     {
@@ -271,9 +272,66 @@ update_path (path, key)
   else
     result = xstrdup (path);
 
+#ifndef ALWAYS_STRIP_DOTDOT
+#define ALWAYS_STRIP_DOTDOT 0
+#endif
+
+  p = result;
+  while (1)
+    {
+      char *src, *dest;
+
+      p = strchr (p, '.');
+      if (p == NULL)
+	break;
+      /* Look for `/../'  */
+      if (p[1] == '.'
+	  && IS_DIR_SEPARATOR (p[2])
+	  && (p != result && IS_DIR_SEPARATOR (p[-1])))
+	{
+	  *p = 0;
+	  if (!ALWAYS_STRIP_DOTDOT && access (result, X_OK) == 0)
+	    {
+	      *p = '.';
+	      break;
+	    }
+	  else
+	    {
+	      /* We can't access the dir, so we won't be able to
+		 access dir/.. either.  Strip out `dir/../'.  If `dir'
+		 turns out to be `.', strip one more path component.  */
+	      dest = p;
+	      do
+		{
+		  --dest;
+		  while (dest != result && IS_DIR_SEPARATOR (*dest))
+		    --dest;
+		  while (dest != result && !IS_DIR_SEPARATOR (dest[-1]))
+		    --dest;
+		}
+	      while (dest != result && *dest == '.');
+	      /* If we have something like `./..' or `/..', don't
+		 strip anything more.  */
+	      if (*dest == '.' || IS_DIR_SEPARATOR (*dest))
+		{
+		  *p = '.';
+		  break;
+		}
+	      src = p + 3;
+	      while (IS_DIR_SEPARATOR (*src))
+		++src;
+	      p = dest;
+	      while ((*dest++ = *src++) != 0)
+		;
+	    }
+	}
+      else
+	++p;
+    }
+
 #ifdef UPDATE_PATH_HOST_CANONICALIZE
   /* Perform host dependent canonicalization when needed.  */
-  UPDATE_PATH_HOST_CANONICALIZE (path);
+  UPDATE_PATH_HOST_CANONICALIZE (result);
 #endif
 
 #ifdef DIR_SEPARATOR_2