[added read-library and validate-catalog procedures
atsmyles@earthlink.net**20100429035636
 Ignore-this: ad6aa0683b6c34b0c80a4de23037d655
] hunk ./catalog.scm 182
-	       
-	
+; given a uri or a version, returns the library form. 
+(define (read-library version-or-uri)
+ (cond
+    ((version? version-or-uri) (read-library (version-uri version-or-uri)))
+    ((string? version-or-uri) (read-library (uri version-or-uri)))
+    ((uri? version-or-uri)
+     (let* ((fragment (uri-fragment version-or-uri))
+	    (path (uri-part version-or-uri 'path))
+	    (reader (if fragment 
+		     (lambda () 
+		      (let loop ((i (string->number fragment))) 
+		       (if (= i 0) (read) (begin (read) (loop (- i 1)))))) 
+		     read)))
+
+      (with-input-from-file path reader)))
+    (else (assertion-violation 'read-library "argument must be a version or a uri" version-or-uri))))
+
+;validate a catalog. Checks that all the files are reachable and that the name and version of the library matches what is registered in the catalog.
+(define (validate-catalog base-dir catalog)
+   (define (check-library library)
+	(for-each (lambda (v)
+	    (cond
+ 		((or (not (uri-scheme (version-uri v))) (not (eq? 'file (uri-scheme (version-uri v))))) 
+			(assertion-violation 'ex:validate-catalog "We only support file based uris" library v))
+		((not (file-exists? (uri-part (version-uri v) 'path))) 
+			(assertion-violation 'ex:validate-catalog "file not found!" library v))
+		(else (call-with-values (lambda () (name&version (cadr (read-library v))))
+			(lambda (name version)
+			    (cond
+				((not (equal? (library-name library) name))
+					(assertion-violation 'validate-catalog "library name in catalog is not the same as library name in version!" name library))
+				((not (equal? (version-number v) version))
+					(assertion-violation 'validate-catalog "library version in catalog does not have the same number as the library form" version v))))))
+			))
+	   (library-versions library)))
+   
+   (let ((libraries (catalog->libraries base-dir catalog)))
+	(for-each check-library libraries)
+        catalog))