[fireball] 38808: - RtlUnicodeStringToCountedOemString improvements: * Fix zero-sized input string handling, result would be error instead of success and zero output string. * If destination string's MaximumLength and Length are equal, it's not an erroneous situation (in fact, a very common situation). * Add comments.

Author: fireball
Date: Sat Jan 17 01:44:28 2009
New Revision: 38808

URL: http://svn.reactos.org/svn/reactos?rev=38808&view=rev
Log:
- RtlUnicodeStringToCountedOemString improvements:
 * Fix zero-sized input string handling, result would be error instead of success and zero
output string.
 * If destination string's MaximumLength and Length are equal, it's not an
erroneous situation (in fact, a very common situation).
 * Add comments.

Modified:
    trunk/reactos/lib/rtl/unicode.c

Modified: trunk/reactos/lib/rtl/unicode.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/rtl/unicode.c?rev=3880…
==============================================================================
--- trunk/reactos/lib/rtl/unicode.c [iso-8859-1] (original)
+++ trunk/reactos/lib/rtl/unicode.c [iso-8859-1] Sat Jan 17 01:44:28 2009
@@ -1492,38 +1492,47 @@
 
     PAGED_CODE_RTL();
 
+    /* Calculate size of the string */
     Length = RtlUnicodeStringToCountedOemSize(UniSource);
 
+    /* If it's 0 then zero out dest string and return */
     if (!Length)
     {
         RtlZeroMemory(OemDest, sizeof(OEM_STRING));
-    }
-
+        return STATUS_SUCCESS;
+    }
+
+    /* Check if length is a sane value */
     if (Length > MAXUSHORT) return STATUS_INVALID_PARAMETER_2;
 
+    /* Store it in dest string */
     OemDest->Length = (USHORT)Length;
 
+    /* If we're asked to alloc the string - do so */
     if (AllocateDestinationString)
     {
         OemDest->Buffer = RtlpAllocateStringMemory(Length, TAG_OSTR);
         OemDest->MaximumLength = Length;
         if (!OemDest->Buffer) return STATUS_NO_MEMORY;
     }
-    else if (OemDest->Length >= OemDest->MaximumLength)
+    else if (OemDest->Length > OemDest->MaximumLength)
     {
         return STATUS_BUFFER_OVERFLOW;
     }
 
+    /* Do the conversion */
     Status = RtlUnicodeToOemN(OemDest->Buffer,
                               OemDest->Length,
                               &Index,
                               UniSource->Buffer,
                               UniSource->Length);
 
-    /* FIXME: Special check needed and return STATUS_UNMAPPABLE_CHARACTER */
+    /* FIXME: Check if everything mapped correctly and
+     * return STATUS_UNMAPPABLE_CHARACTER */
 
     if (!NT_SUCCESS(Status) && AllocateDestinationString)
     {
+        /* Conversion failed, free dest string and return status code */
         RtlpFreeStringMemory(OemDest->Buffer, TAG_OSTR);
         OemDest->Buffer = NULL;
         return Status;