r31875-comment.diff

Index: load.c
===================================================================
--- load.c	(revision 31933)
+++ load.c	(working copy)
@@ -68,41 +68,66 @@
     return GET_VM()->loading_table;
 }
 
+// If the given loaded_name looks match with the given feature, it returns
+// the loaded path in $LOAD_PATH where the loaded_name is considered to be
+// loaded from. Otherwise, it returns 0.
+//
+// ex. /usr/lib/ruby/1.9.1/logger.rb, logger
+//     => /usr/lib/ruby/1.9.1
+// ex. /usr/lib/ruby/1.9.1/rubygems/version.rb, version
+//     => generally 0 since $LOAD_PATH does not include '/usr/lib/ruby/1.9.1'
+//
+// Returned value is only used as a flag for indicating 'found' or 'not found.'
+// So it's the function for 'is this feature matches with this loaded_feature?'
+//
 static VALUE
-loaded_feature_path(const char *name, long vlen, const char *feature, long len,
+loaded_feature_path(const char *loaded_name, long nlen, const char *feature, long flen,
 		    int type, VALUE load_path)
 {
     long i;
     long plen;
     const char *e;
 
-    if(vlen < len) return 0;
-    if (!strncmp(name+(vlen-len),feature,len)){
-	plen = vlen - len - 1;
+    if(nlen < flen) return 0;
+
+    // set path length of load_name if the given loaded_name looks match with the feature.
+
+    // set plen temporarily
+    long plen = nlen - flen;
+    if (!strncmp(loaded_name + plen, feature, flen)){
+	// tail match
+	plen = plen - 1;
     } else {
-	for (e = name + vlen; name != e && *e != '.' && *e != '/'; --e);
-	if (*e!='.' ||
-	    e-name < len ||
-	    strncmp(e-len,feature,len) )
+	// scan ext part of loaded_name
+	for (e = loaded_name + nlen; loaded_name != e && *e != '.' && *e != '/'; --e);
+	if (*e != '.' || // no extension
+	    e - loaded_name < flen || // feature cannot match this loaded_name
+	    strncmp(e - flen, feature, flen) ) // basename does not match
 	    return 0;
-	plen = e - name - len - 1;
+	// basename match
+	plen = e - loaded_name - flen - 1;
     }
+
+    // search path in $LOAD_PATH
     for (i = 0; i < RARRAY_LEN(load_path); ++i) {
-	VALUE p = RARRAY_PTR(load_path)[i];
-	const char *s = StringValuePtr(p);
-	long n = RSTRING_LEN(p);
+	VALUE path = RARRAY_PTR(load_path)[i];
+	const char *cpath = StringValuePtr(path);
+	long len = RSTRING_LEN(path);
 
-	if (n != plen ) continue;
-	if (n && (strncmp(name, s, n) || name[n] != '/')) continue;
+	if (len != plen ) continue; // path length does not match
+	if (len && (strncmp(loaded_name, cpath, len) || loaded_name[len] != '/')) continue; // path part does not match
 	switch (type) {
 	  case 's':
-	    if (IS_DLEXT(&name[n+len+1])) return p;
+	    // check if it's EXT (.so) if type is specified
+	    if (IS_DLEXT(&loaded_name[len + flen + 1])) return path;
 	    break;
 	  case 'r':
-	    if (IS_RBEXT(&name[n+len+1])) return p;
+	    // check if it's Ruby (.rb) if type is specified
+	    if (IS_RBEXT(&loaded_name[len + flen + 1])) return path;
 	    break;
 	  default:
-	    return p;
+	    // type is not specified
+	    return path;
 	}
     }
     return 0;