3 files changed, 26 insertions, 11 deletions
diff --git a/generic/tclLoad.c b/generic/tclLoad.c
index 7ea1ebd..ee1862d 100644
--- a/generic/tclLoad.c
+++ b/generic/tclLoad.c
@@ -544,7 +544,7 @@ Tcl_LoadObjCmd(
  *
  * Tcl_UnloadObjCmd --
  *
- *	This function is invoked to process the "unload" Tcl command. See the
+ *	Implements the the "unload" Tcl command. See the
  *	user documentation for details on what it does.
  *
  * Results:
@@ -764,6 +764,23 @@ Tcl_UnloadObjCmd(
     return code;
 }
 
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * UnloadLibrary --
+ *
+ *	Unloads a library from an interpreter, and also from the process if it
+ *	is unloadable, i.e. if it provides an "unload" function.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	See description.
+ *
+ *----------------------------------------------------------------------
+ */
 static int
 UnloadLibrary(
 	Tcl_Interp *interp,
@@ -884,11 +901,9 @@ UnloadLibrary(
     }
 
     /*
-     * The unload function executed fine. Examine the reference count to see
-     * if we unload the DLL.
+     * The unload function was called succesfully.
      */
 
-
     Tcl_MutexLock(&libraryMutex);
     if (Tcl_IsSafe(target)) {
 	libraryPtr->safeInterpRefCount--;
@@ -917,7 +932,7 @@ UnloadLibrary(
 
     code = TCL_OK;
     if (libraryPtr->safeInterpRefCount <= 0 && libraryPtr->interpRefCount <= 0
-	    && !keepLibrary) {
+	    && (unloadProc != NULL) && !keepLibrary) {
 	/*
 	 * Unload the shared library from the application memory...
 	 */
diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c
index 2b11877..d43c507 100644
--- a/generic/tclStringObj.c
+++ b/generic/tclStringObj.c
@@ -145,14 +145,14 @@ typedef struct {
 } UniCharString;
 
 #define UNICHAR_STRING_MAXCHARS \
-    (int)(((size_t)UINT_MAX - 1 - offsetof(UniCharString, unicode))/sizeof(Tcl_UniChar))
+    (int)(((size_t)UINT_MAX  - offsetof(UniCharString, unicode))/sizeof(Tcl_UniChar) - 1)
 #define UNICHAR_STRING_SIZE(numChars) \
-    (offsetof(UniCharString, unicode) + (((numChars) + 1U) * sizeof(Tcl_UniChar)))
+    (offsetof(UniCharString, unicode) + sizeof(Tcl_UniChar) + ((numChars) * sizeof(Tcl_UniChar)))
 #define uniCharStringCheckLimits(numChars) \
     do {								\
 	if ((numChars) < 0 || (numChars) > UNICHAR_STRING_MAXCHARS) {		\
 	    Tcl_Panic("max length for a Tcl unicode value (%d chars) exceeded", \
-		      (int)UNICHAR_STRING_MAXCHARS);					\
+		      UNICHAR_STRING_MAXCHARS);					\
 	}								\
     } while (0)
 #define uniCharStringAttemptAlloc(numChars) \
diff --git a/generic/tclStringRep.h b/generic/tclStringRep.h
index cac4d0b..faa2c2c 100644
--- a/generic/tclStringRep.h
+++ b/generic/tclStringRep.h
@@ -60,14 +60,14 @@ typedef struct {
 } String;
 
 #define STRING_MAXCHARS \
-    (int)(((size_t)UINT_MAX - 1 - offsetof(String, unicode))/sizeof(unsigned short))
+    (int)(((size_t)UINT_MAX - offsetof(String, unicode))/sizeof(unsigned short) - 1)
 #define STRING_SIZE(numChars) \
-    (offsetof(String, unicode) + (((numChars) + 1U) * sizeof(unsigned short)))
+    (offsetof(String, unicode) + sizeof(unsigned short) + ((numChars) * sizeof(unsigned short)))
 #define stringCheckLimits(numChars) \
     do {								\
 	if ((numChars) < 0 || (numChars) > STRING_MAXCHARS) {		\
 	    Tcl_Panic("max length for a Tcl unicode value (%d chars) exceeded", \
-		      (int)STRING_MAXCHARS);					\
+		      STRING_MAXCHARS);					\
 	}								\
     } while (0)
 #define stringAttemptAlloc(numChars) \