- Added feature to ensure include files come from the right place. The

order in which Scyther searches for files is now.
   1. From the prefix of the previously found file.
   2. Current directory.
   3. Anything in SPDLDIRS
  Here, 1 is new.
- When using -E (--expert), scyther shows any files it reads on stderr.

src/switches.c

@@ -23,6 +23,8 @@ extern struct tacnode *spdltac;
 const char *progname = "scyther";
 const char *releasetag = SVNVERSION;
 
+char *lastfoundprefix = NULL;
+
 // Forward declarations
 void process_environment (void);
 void process_switches (int commandline);
@@ -93,12 +95,19 @@ switchesInit (int argc, char **argv)
 void
 switchesDone (void)
 {
+  if (lastfoundprefix != NULL)
+    free (lastfoundprefix);
 }
 
 //! Open a (protocol) file.
 /**
  * Uses the environment variable SCYTHERDIR to also search for files
  *
+ * If a file was opened before, this is stored in the static char* (initially
+ * NULL) lastfoundprefix. This prefix can override any other: the point of it is that
+ * if you find a file in a non-standard location, which then does an include,
+ * you want this to refer to the directory where you found that last file.
+ *
  * If reopener == NULL then we open a new file pointer, otherwise reopen this one.
  */
 FILE *
@@ -108,6 +117,9 @@ openFileSearch (char *filename, FILE * reopener)
   char *dirs;
 
   //! try a filename and a prefix.
+  /**
+   * Prefixes don't have to end with "/"; this will be added automatically.
+   */
   int try (char *prefix)
   {
     char *buffer = NULL;
@@ -125,7 +137,7 @@ openFileSearch (char *filename, FILE * reopener)
     buflen = prefixlen + namelen + 1;
 
     // Does the prefix end with a slash? (it should)
-    if (nameindex > 0 && prefix[nameindex - 1] != '/')
+    if (prefixlen > 0 && prefix[prefixlen - 1] != '/')
       {
 	addslash = true;
 	buflen++;
@@ -139,38 +151,65 @@ openFileSearch (char *filename, FILE * reopener)
 
     // Add the slash in the center
     if (addslash)
-      {
+      buffer[nameindex - 1] = '/';
-	buffer[nameindex - 1] = '/';
-      }
 
     // Now try to open it
     if (reopener != NULL)
       {
 	if (freopen (buffer, "r", reopener) != NULL)
-	  {
+	  result = true;
-	    result = true;
-	  }
       }
     else
       {
 	reopener = fopen (buffer, "r");
 	if (reopener != NULL)
-	  {
+	  result = true;
-	    result = true;
-	  }
       }
 
+    if (result)
+      {
+	// There is a result. Does it have a prefix?
+	char *ls;
+
+	// Non-standard location, maybe we should warn for that
+	if (switches.expert)
+	  {
+	    globalError++;
+	    eprintf ("Reading file %s.\n", buffer);
+	    globalError--;
+	  }
+
+	// Compute the prefix (simply scan for the last slash, if any)
+	ls = strrchr (buffer, '/');
+	if (ls != NULL)
+	  {
+	    // Store it for any next includes or something like that
+	    // Clear the old one
+	    if (lastfoundprefix != NULL)
+	      free (lastfoundprefix);
+	    ls[0] = '\0';
+	    lastfoundprefix = buffer;
+	    return true;
+	  }
+      }
     free (buffer);
     return result;
   }
 
   // main code.
 
-  if (try (""))
+  // Try last file prefix (if it exists!)
+  if (lastfoundprefix != NULL)
     {
-      return reopener;
+      if (try (lastfoundprefix))
+	return reopener;
     }
 
+  // Try current directory
+
+  if (try (""))
+    return reopener;
+
   // Now try the environment variable
   dirs = getenv ("SCYTHERDIR");
   while (dirs != NULL)
@@ -179,9 +218,7 @@ openFileSearch (char *filename, FILE * reopener)
 	{
 	  // try this one
 	  if (try (dirs))
-	    {
+	    return reopener;
-	      return reopener;
-	    }
 	  // skip to next
 	  dirs = strpbrk (dirs, separators);
 	  if (dirs != NULL)