- Finish implementing RtlFindUnicodePrefix. The Windows NPFS driver should load now...
[reactos.git] / reactos / lib / rtl / unicodeprefix.c
index 1ee569f..a9079d2 100644 (file)
@@ -2,8 +2,8 @@
  * COPYRIGHT:         See COPYING in the top level directory
  * PROJECT:           ReactOS system libraries
  * PURPOSE:           Unicode Prefix implementation
- * FILE:              lib/rtl/unicodeprfx.c
- * PROGRAMMER:        
+ * FILE:              lib/rtl/unicodeprefix.c
+ * PROGRAMMER:        Alex Ionescu (alex@relsoft.net) 
  */
 
 /* INCLUDES *****************************************************************/
 #define NDEBUG
 #include <debug.h>
 
+/*
+ * FIXME: Try to find the official names and add to NDK
+ * Definitions come from fastfat driver.
+ */
+typedef USHORT NODE_TYPE_CODE;
+#define PFX_NTC_TABLE       ((NODE_TYPE_CODE)0x0800)
+#define PFX_NTC_ROOT        ((NODE_TYPE_CODE)0x0801)
+#define PFX_NTC_CHILD       ((NODE_TYPE_CODE)0x0802)
+#define PFX_NTC_CASE_MATCH  ((NODE_TYPE_CODE)0x0803)
+
 /* FUNCTIONS ***************************************************************/
 
+STATIC
+ULONG
+NTAPI
+ComputeUnicodeNameLength(IN PUNICODE_STRING UnicodeName)
+{
+    ULONG Chars = UnicodeName->Length / sizeof(WCHAR);
+    ULONG i, NamesFound = 1;
+
+    /* Loop the string */
+    for (i = 0; i < (Chars - 1); i++)
+    {
+        /* Check if we found a backslash, meaning another name */
+        if (UnicodeName->Buffer[i] == '\\') NamesFound++;
+    }
+
+    /* Return the number of names found */
+    return NamesFound;
+}
+
+
+STATIC
+RTL_GENERIC_COMPARE_RESULTS
+NTAPI
+CompareUnicodeStrings(IN PUNICODE_STRING String,
+                      IN PUNICODE_STRING Prefix,
+                      IN ULONG CaseCheckChar)
+{
+    ULONG StringLength = String->Length / sizeof(WCHAR);
+    ULONG PrefixLength = Prefix->Length / sizeof(WCHAR);
+    ULONG ScanLength = min(StringLength, PrefixLength);
+    ULONG i;
+    WCHAR FoundPrefix, FoundString;
+    PWCHAR p, p1;
+
+    /* Validate the Case Check Character Position */
+    if (CaseCheckChar > ScanLength) CaseCheckChar = ScanLength;
+
+    /* Do the case sensitive comparison first */
+    for (i = 0; i < CaseCheckChar; i++)
+    {
+        /* Compare the two characters */
+        if (Prefix->Buffer[i] != String->Buffer[i]) break;
+    }
+
+    /* Save the characters we found */
+    FoundPrefix = Prefix->Buffer[i];
+    FoundString = String->Buffer[i];
+
+    /* Check if we exausted the search above */
+    if (i == CaseCheckChar)
+    {
+        /* Do a case-insensitive search */
+        p = &Prefix->Buffer[i];
+        p1 = &String->Buffer[i];
+        do
+        {
+            /* Move to the next character */
+            FoundPrefix = *p++;
+            FoundString = *p1++;
+
+            /* Compare it */
+            if (FoundPrefix != FoundString)
+            {
+                /* Upcase the characters */
+                FoundPrefix = RtlUpcaseUnicodeChar(FoundPrefix);
+                FoundString = RtlUpcaseUnicodeChar(FoundString);
+
+                /* Compare them again */
+                if (FoundPrefix != FoundString) break;
+            }
+
+            /* Move to the next char */
+            i++;
+        } while (i < ScanLength);
+    }
+
+    /* Check if we weren't able to find a match in the loops */
+    if (i < ScanLength)
+    {
+        /* If the prefix character found was a backslash, this is a less */
+        if (FoundPrefix == '\\') return GenericLessThan;
+
+        /* If the string character found was a backslack, then this is a more */
+        if (FoundString == '\\') return GenericGreaterThan;
+
+        /* None of those two special cases, do a normal check */
+        if (FoundPrefix < FoundString) return GenericLessThan;
+
+        /* The only choice left is that Prefix > String */
+        return GenericGreaterThan;
+    }
+
+    /* If we got here, a match was found. Check if the prefix is smaller */
+    if (PrefixLength < StringLength)
+    {
+        /* Check if the string is actually a prefix */
+        if (String->Buffer[PrefixLength] == '\\') return -1;
+
+        /* It's not a prefix, and it's shorter, so it's a less */
+        return GenericLessThan;
+    }
+    
+    /* Check if the prefix is longer */
+    if (PrefixLength > StringLength) return GenericGreaterThan;
+
+    /* If we got here, then they are 100% equal */
+    return GenericEqual;
+}
+
 /*
-* @unimplemented
-*/
+ * @implemented
+ */
 PUNICODE_PREFIX_TABLE_ENTRY
-STDCALL
-RtlFindUnicodePrefix (
-       PUNICODE_PREFIX_TABLE PrefixTable,
-       PUNICODE_STRING FullName,
-       ULONG CaseInsensitiveIndex
-       )
+NTAPI
+RtlFindUnicodePrefix(PUNICODE_PREFIX_TABLE PrefixTable,
+                     PUNICODE_STRING FullName,
+                     ULONG CaseInsensitiveIndex)
 {
-       UNIMPLEMENTED;
-       return 0;
+    ULONG NameCount;
+    PUNICODE_PREFIX_TABLE_ENTRY CurrentEntry, PreviousEntry, Entry, NextEntry;
+    PRTL_SPLAY_LINKS SplayLinks;
+    RTL_GENERIC_COMPARE_RESULTS Result;
+
+    /* Find out how many names there are */
+    NameCount = ComputeUnicodeNameLength(FullName);
+
+    /* Find the right spot where to start looking for this entry */
+    PreviousEntry = (PUNICODE_PREFIX_TABLE_ENTRY)PrefixTable;
+    CurrentEntry = PreviousEntry->NextPrefixTree;
+    while (CurrentEntry->NameLength > NameCount)
+    {
+        /* Not a match, move to the next entry */
+        PreviousEntry = CurrentEntry;
+        CurrentEntry = CurrentEntry->NextPrefixTree;
+    }
+
+    /* Loop every entry which has valid entries */
+    while (CurrentEntry->NameLength)
+    {
+        /* Get the splay links and loop */
+        while ((SplayLinks = &CurrentEntry->Links))
+        {
+            /*
+             * Implementation notes:
+             *  - get the entry
+             *  - compare the entry's prefix with the fullname:
+             *    if greater: restart on the left child
+             *    if lesser: restart on the right child
+             *  - else if equal:
+             *    for caseinsensitive, just return the entry and
+             *        splay it and set it as root if it's a child
+             *    for casesensitive, loop the circular case match list and
+             *        keep comparing for each entry
+             */
+            Entry = CONTAINING_RECORD(SplayLinks,
+                                      UNICODE_PREFIX_TABLE_ENTRY,
+                                      Links);
+
+            /* Do the comparison */
+            Result = CompareUnicodeStrings(Entry->Prefix, FullName, 0);
+            if (Result == GenericGreaterThan)
+            {
+                /* Prefix is greater, so restart on the left child */
+                SplayLinks = RtlLeftChild(SplayLinks);
+                continue;
+            }
+            else if (Result == GenericLessThan)
+            {
+                /* Prefix is smaller, so restart on the right child */
+                SplayLinks = RtlRightChild(SplayLinks);
+                continue;
+            }
+
+            /*
+             * We have a match, check if this was a case-sensitive search
+             * NOTE: An index of 0 means case-insensitive(ie, we'll be case
+             * insensitive since index 0, ie, all the time)
+             */
+            if (!CaseInsensitiveIndex)
+            {
+                /* 
+                 * Check if this entry was a child. We need to return the root,
+                 * so if this entry was a child, we'll splay the tree and get
+                 * the root, and set the current entry as a child.
+                 */
+                if (Entry->NodeTypeCode == PFX_NTC_CHILD)
+                {
+                    /* Get the next entry */
+                    NextEntry = CurrentEntry->NextPrefixTree;
+
+                    /* Make the current entry become a child */
+                    CurrentEntry->NodeTypeCode = PFX_NTC_CHILD;
+                    CurrentEntry->NextPrefixTree = NULL;
+
+                    /* Splay the tree */
+                    SplayLinks = RtlSplay(&Entry->Links);
+
+                    /* Get the new root entry */
+                    Entry = CONTAINING_RECORD(SplayLinks,
+                                              UNICODE_PREFIX_TABLE_ENTRY,
+                                              Links);
+
+                    /* Set it as a root entry */
+                    Entry->NodeTypeCode = PFX_NTC_ROOT;
+
+                    /* Add it to the root entries list */
+                    PreviousEntry->NextPrefixTree = Entry;
+                    Entry->NextPrefixTree = NextEntry;
+                }
+
+                /* Return the entry */
+                return Entry;
+            }
+
+            /* We'll do a case-sensitive search if we've reached this point */
+            NextEntry = Entry;
+            do
+            {
+                /* Do the case-sensitive search */
+                Result = CompareUnicodeStrings(NextEntry->Prefix,
+                                               FullName,
+                                               CaseInsensitiveIndex);
+                if ((Result != GenericLessThan) &&
+                    (Result != GenericGreaterThan))
+                {
+                    /* This is a positive match, return it */
+                    return NextEntry;
+                }
+
+                /* No match yet, continue looping the circular list */
+                NextEntry = NextEntry->CaseMatch;
+            } while (NextEntry != Entry);
+
+            /*
+             * If we got here, then we found a non-case-sensitive match, but
+             * we need to find a case-sensitive match, so we'll just keep 
+             * searching the next tree (NOTE: we need to break out for this).
+             */
+            break;
+        }
+
+        /* Splay links exausted, move to next entry */
+        PreviousEntry = CurrentEntry;
+        CurrentEntry = CurrentEntry->NextPrefixTree;
+    }
+
+       /* If we got here, nothing was found */
+       return NULL;
 }
 
 /*
-* @unimplemented
-*/
+ * @implemented
+ */
 VOID
-STDCALL
-RtlInitializeUnicodePrefix (
-       PUNICODE_PREFIX_TABLE PrefixTable
-       )
+NTAPI
+RtlInitializeUnicodePrefix(PUNICODE_PREFIX_TABLE PrefixTable)
 {
-       UNIMPLEMENTED;
+       /* Setup the table */
+    PrefixTable->NameLength = 0;
+    PrefixTable->LastNextEntry = NULL;
+    PrefixTable->NodeTypeCode = PFX_NTC_TABLE;
+    PrefixTable->NextPrefixTree = (PUNICODE_PREFIX_TABLE_ENTRY)PrefixTable;
 }
 
 /*
-* @unimplemented
-*/
+ * @implemented
+ */
 BOOLEAN
-STDCALL
-RtlInsertUnicodePrefix (
-       PUNICODE_PREFIX_TABLE PrefixTable,
-       PUNICODE_STRING Prefix,
-       PUNICODE_PREFIX_TABLE_ENTRY PrefixTableEntry
-       )
+NTAPI
+RtlInsertUnicodePrefix(PUNICODE_PREFIX_TABLE PrefixTable,
+                       PUNICODE_STRING Prefix,
+                       PUNICODE_PREFIX_TABLE_ENTRY PrefixTableEntry)
 {
-       UNIMPLEMENTED;
-       return FALSE;
+    PUNICODE_PREFIX_TABLE_ENTRY CurrentEntry, PreviousEntry, Entry, NextEntry;
+    ULONG NameCount;
+    RTL_GENERIC_COMPARE_RESULTS Result;
+    PRTL_SPLAY_LINKS SplayLinks;
+
+    /* Find out how many names there are */
+    NameCount = ComputeUnicodeNameLength(Prefix);
+
+    /* Set up the initial entry data */
+    PrefixTableEntry->NameLength = NameCount;
+    PrefixTableEntry->Prefix = Prefix;
+    RtlInitializeSplayLinks(&PrefixTableEntry->Links);
+
+    /* Find the right spot where to insert this entry */
+    PreviousEntry = (PUNICODE_PREFIX_TABLE_ENTRY)PrefixTable;
+    CurrentEntry = PreviousEntry->NextPrefixTree;
+    while (CurrentEntry->NameLength > NameCount)
+    {
+        /* Not a match, move to the next entry */
+        PreviousEntry = CurrentEntry;
+        CurrentEntry = CurrentEntry->NextPrefixTree;
+    }
+
+    /* Check if we did find a tree by now */
+    if (CurrentEntry->NameLength != NameCount)
+    {
+        /* We didn't, so insert a new entry in the list */
+        PreviousEntry->NextPrefixTree = PrefixTableEntry;
+        PrefixTableEntry->NextPrefixTree = CurrentEntry;
+
+        /* This is now a root entry with case match */
+        PrefixTableEntry->NodeTypeCode = PFX_NTC_ROOT;
+        PrefixTableEntry->CaseMatch = PrefixTableEntry;
+
+        /* Quick return */
+        return TRUE;
+    }
+
+    /* We found a tree, so star thte search loop */
+    Entry = CurrentEntry;
+    while (TRUE)
+    {
+        /* Do a case-insensitive comparison to find out the match level */
+        Result = CompareUnicodeStrings(Entry->Prefix, Prefix, 0);
+        if (Result == GenericEqual)
+        {
+            /* We have a match, start doing a case-sensitive search */
+            NextEntry = Entry;
+
+            /* Search the circular case-match list */
+            do
+            {
+                /* Check if we found a match */
+                if (CompareUnicodeStrings(NextEntry->Prefix, Prefix, -1) ==
+                    (GenericEqual))
+                {
+                    /* We must fail the insert: it already exists */
+                    return FALSE;
+                }
+
+                /* Move to the next entry in the circular list */
+                NextEntry = NextEntry->CaseMatch;
+            }
+            while (NextEntry != Entry);
+
+            /*
+             * No match found, so we can safely insert it. Remember that a
+             * case insensitive match was found, so this is not a ROOT NTC
+             * but a Case Match NTC instead.
+             */
+            PrefixTableEntry->NodeTypeCode = PFX_NTC_CASE_MATCH;
+            PrefixTableEntry->NextPrefixTree = NULL;
+            
+            /* Insert it into the circular list */
+            PrefixTableEntry->CaseMatch = Entry->CaseMatch;
+            Entry->CaseMatch = PrefixTableEntry;
+        }
+        else if (Result == GenericGreaterThan)
+        {
+            /* Check out if we have a left child */
+            if (RtlLeftChild(&Entry->Links))
+            {
+                /* We do, enter it and restart the loop */
+                SplayLinks = RtlLeftChild(&Entry->Links);
+                Entry = CONTAINING_RECORD(SplayLinks,
+                                          UNICODE_PREFIX_TABLE_ENTRY,
+                                          Links);
+            }
+            else
+            {
+                /* We don't, set this entry as a child */
+                PrefixTableEntry->NodeTypeCode = PFX_NTC_CHILD;
+                PrefixTableEntry->NextPrefixTree = NULL;
+                PrefixTableEntry->CaseMatch = PrefixTableEntry;
+
+                /* Insert us into the tree */
+                RtlInsertAsLeftChild(&Entry->Links, &PrefixTableEntry->Links);
+                break;
+            }
+        }
+        else
+        {
+            /* Check out if we have a right child */
+            if (RtlRightChild(&Entry->Links))
+            {
+                /* We do, enter it and restart the loop */
+                SplayLinks = RtlLeftChild(&Entry->Links);
+                Entry = CONTAINING_RECORD(SplayLinks,
+                                          UNICODE_PREFIX_TABLE_ENTRY,
+                                          Links);
+            }
+            else
+            {
+                /* We don't, set this entry as a child */
+                PrefixTableEntry->NodeTypeCode = PFX_NTC_CHILD;
+                PrefixTableEntry->NextPrefixTree = NULL;
+                PrefixTableEntry->CaseMatch = PrefixTableEntry;
+
+                /* Insert us into the tree */
+                RtlInsertAsRightChild(&Entry->Links, &PrefixTableEntry->Links);
+                break;
+            }
+        }
+    }
+
+    /* Get the next tree entry */
+    NextEntry = CurrentEntry->NextPrefixTree;
+
+    /* Set what was the current entry to a child entry */
+    CurrentEntry->NodeTypeCode = PFX_NTC_CHILD;
+    CurrentEntry->NextPrefixTree = NULL;
+
+    /* Splay the tree */
+    SplayLinks = RtlSplay(&Entry->Links);
+
+    /* The link points to the root, get it */
+    Entry = CONTAINING_RECORD(SplayLinks, UNICODE_PREFIX_TABLE_ENTRY, Links);
+
+    /* Mark the root as a root entry */
+    Entry->NodeTypeCode = PFX_NTC_ROOT;
+
+    /* Add it to the tree list */
+    PreviousEntry->NextPrefixTree = Entry;
+    Entry->NextPrefixTree = NextEntry;
+
+    /* Return success */
+       return TRUE;
 }
 
 /*
-* @unimplemented
+* @implemented
 */
 PUNICODE_PREFIX_TABLE_ENTRY
-STDCALL
-RtlNextUnicodePrefix (
-       PUNICODE_PREFIX_TABLE PrefixTable,
-       BOOLEAN Restart
-       )
+NTAPI
+RtlNextUnicodePrefix(PUNICODE_PREFIX_TABLE PrefixTable,
+                     BOOLEAN Restart)
 {
-       UNIMPLEMENTED;
-       return 0;
+    PRTL_SPLAY_LINKS SplayLinks;
+    PUNICODE_PREFIX_TABLE_ENTRY Entry, CaseMatchEntry;
+
+    /* We might need this entry 2/3rd of the time, so cache it now */
+    CaseMatchEntry = PrefixTable->LastNextEntry->CaseMatch;
+
+    /* Check if this is a restart or if we don't have a last entry */
+    if ((Restart) || !(PrefixTable->LastNextEntry))
+    {
+        /* Get the next entry and validate it */
+        Entry = PrefixTable->NextPrefixTree;
+        if (Entry->NodeTypeCode == PFX_NTC_TABLE) return NULL;
+
+        /* Now get the Splay Tree Links */
+        SplayLinks = &Entry->Links;
+
+        /* Loop until we get the first node in the tree */
+        while (RtlLeftChild(SplayLinks)) SplayLinks = RtlLeftChild(SplayLinks);
+
+        /* Get the entry from it */
+        Entry = CONTAINING_RECORD(SplayLinks,
+                                  UNICODE_PREFIX_TABLE_ENTRY,
+                                  Links);
+    }
+    else if (CaseMatchEntry->NodeTypeCode == PFX_NTC_CASE_MATCH)
+    {
+        /* If the last entry was a Case Match, then return it */
+        Entry = CaseMatchEntry;
+    }
+    else
+    {
+        /* Find the successor */
+        SplayLinks = RtlRealSuccessor(&CaseMatchEntry->Links);
+        if (!SplayLinks)
+        {
+            /* Didn't find one, we'll have to search the tree */
+            SplayLinks = &PrefixTable->LastNextEntry->Links;
+
+            /* Get the topmost node (root) */
+            while (!RtlIsRoot(SplayLinks)) SplayLinks = RtlParent(SplayLinks);
+            Entry = CONTAINING_RECORD(SplayLinks,
+                                      UNICODE_PREFIX_TABLE_ENTRY,
+                                      Links);
+
+            /* Get its tree and make sure somethign is in it */
+            Entry = Entry->NextPrefixTree;
+            if (Entry->NameLength <= 0) return NULL;
+
+            /* Select these new links and find the first node */
+            while (RtlLeftChild(SplayLinks)) SplayLinks = RtlLeftChild(SplayLinks);
+        }
+
+        /* Get the entry from it */
+        Entry = CONTAINING_RECORD(SplayLinks,
+                                  UNICODE_PREFIX_TABLE_ENTRY,
+                                  Links);
+    }
+
+    /* Save this entry as the last one returned, and return it */
+    PrefixTable->LastNextEntry = Entry;
+    return Entry;
 }
 
 /*
-* @unimplemented
-*/
+ * @implemented
+ */
 VOID
-STDCALL
-RtlRemoveUnicodePrefix (
-       PUNICODE_PREFIX_TABLE PrefixTable,
-       PUNICODE_PREFIX_TABLE_ENTRY PrefixTableEntry
-       )
+NTAPI
+RtlRemoveUnicodePrefix(PUNICODE_PREFIX_TABLE PrefixTable,
+                       PUNICODE_PREFIX_TABLE_ENTRY PrefixTableEntry)
 {
-       UNIMPLEMENTED;
+    PUNICODE_PREFIX_TABLE_ENTRY Entry, RefEntry, NewEntry;
+    PRTL_SPLAY_LINKS SplayLinks;
+
+    /* Erase the last entry */
+    PrefixTable->LastNextEntry = NULL;
+
+    /* Check if this was a Case Match Entry */
+    if (PrefixTableEntry->NodeTypeCode == PFX_NTC_CASE_MATCH)
+    {
+        /* Get the case match entry */
+        Entry = PrefixTableEntry->CaseMatch;
+
+        /* Now loop until we find one referencing what the caller sent */
+        while (Entry->CaseMatch != PrefixTableEntry) Entry = Entry->CaseMatch;
+
+        /* We found the entry that was sent, link them to delete this entry */
+        Entry->CaseMatch = PrefixTableEntry->CaseMatch;
+    }
+    else if ((PrefixTableEntry->NodeTypeCode == PFX_NTC_ROOT) ||
+            (PrefixTableEntry->NodeTypeCode == PFX_NTC_CHILD))
+    {
+        /* Check if this entry is a case match */
+        if (PrefixTableEntry->CaseMatch != PrefixTableEntry)
+        {
+            /* Get the case match entry */
+            Entry = PrefixTableEntry->CaseMatch;
+
+            /* Now loop until we find one referencing what the caller sent */
+            while (Entry->CaseMatch != PrefixTableEntry) Entry = Entry->CaseMatch;
+
+            /* We found the entry that was sent, link them to delete this entry */
+            Entry->CaseMatch = PrefixTableEntry->CaseMatch;
+
+            /* Copy the data */
+            Entry->NodeTypeCode = PrefixTableEntry->NodeTypeCode;
+            Entry->NextPrefixTree = PrefixTableEntry->NextPrefixTree;
+            Entry->Links = PrefixTableEntry->Links;
+
+            /* Now check if we are a root entry */
+            if (RtlIsRoot(&PrefixTableEntry->Links))
+            {
+                /* We are, so make this entry root as well */
+                Entry->Links.Parent = &Entry->Links;
+
+                /* Find the entry referencing us */
+                RefEntry = Entry->NextPrefixTree;
+                while (RefEntry->NextPrefixTree != Entry)
+                {
+                    /* Not this one, move to the next entry */
+                    RefEntry = RefEntry->NextPrefixTree;
+                }
+
+                /* Link them to us now */
+                RefEntry->NextPrefixTree = Entry;
+            }
+            else if (RtlIsLeftChild(&PrefixTableEntry->Links))
+            {
+                /* We were the left child, so make us as well */
+                RtlParent(&PrefixTableEntry->Links)->LeftChild = &Entry->Links;
+            }
+            else
+            {
+                /* We were the right child, so make us as well */
+                RtlParent(&PrefixTableEntry->Links)->RightChild = &Entry->Links;
+            }
+
+            /* Check if we have a left child */
+            if (RtlLeftChild(&Entry->Links))
+            {
+                /* Update its parent link */
+                RtlLeftChild(&Entry->Links)->Parent = &Entry->Links;
+            }
+            /* Check if we have a right child */
+            if (RtlRightChild(&Entry->Links))
+            {
+                /* Update its parent link */
+                RtlRightChild(&Entry->Links)->Parent = &Entry->Links;
+            }
+        }
+        else
+        {
+            /* It's not a case match, so we'll delete the actual entry */
+            SplayLinks = &PrefixTableEntry->Links;
+
+            /* Find the root entry */
+            while (!RtlIsRoot(SplayLinks)) SplayLinks = RtlParent(SplayLinks);
+            Entry = CONTAINING_RECORD(SplayLinks,
+                                      UNICODE_PREFIX_TABLE_ENTRY,
+                                      Links);
+
+            /* Delete the entry and check if the whole tree is gone */
+            SplayLinks = RtlDelete(&PrefixTableEntry->Links);
+            if (!SplayLinks)
+            {
+                /* The tree is also gone now, find the entry referencing us */
+                RefEntry = Entry->NextPrefixTree;
+                while (RefEntry->NextPrefixTree != Entry)
+                {
+                    /* Not this one, move to the next entry */
+                    RefEntry = RefEntry->NextPrefixTree;
+                }
+
+                /* Link them so this entry stops being referenced */
+                RefEntry->NextPrefixTree = Entry->NextPrefixTree;
+            }
+            else if (&Entry->Links != SplayLinks)
+            {
+                /* The tree is still here, but we got moved to a new one */
+                NewEntry = CONTAINING_RECORD(SplayLinks,
+                                             UNICODE_PREFIX_TABLE_ENTRY,
+                                             Links);
+
+                /* Find the entry referencing us */
+                RefEntry = Entry->NextPrefixTree;
+                while (RefEntry->NextPrefixTree != Entry)
+                {
+                    /* Not this one, move to the next entry */
+                    RefEntry = RefEntry->NextPrefixTree;
+                }
+
+                /* Since we got moved, make us the new root entry */
+                NewEntry->NodeTypeCode = PFX_NTC_ROOT;
+
+                /* Link us with the entry referencing the old root */
+                RefEntry->NextPrefixTree = NewEntry;
+
+                /* And link us with the old tree */
+                NewEntry->NextPrefixTree = Entry->NextPrefixTree;
+
+                /* Set the old tree as a child */
+                Entry->NodeTypeCode = PFX_NTC_CHILD;
+                Entry->NextPrefixTree = NULL;
+            }
+        }
+    }
 }
 
 /* EOF */