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dll: FspFileSystem*DirectoryBuffer API's
This commit is contained in:
Bill Zissimopoulos
392
src/dll/dirbuf.c
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392
src/dll/dirbuf.c
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/**
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* @file dll/dirbuf.c
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*
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* @copyright 2015-2017 Bill Zissimopoulos
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*/
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/*
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* This file is part of WinFsp.
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*
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* You can redistribute it and/or modify it under the terms of the GNU
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* General Public License version 3 as published by the Free Software
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* Foundation.
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*
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* Licensees holding a valid commercial license may use this file in
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* accordance with the commercial license agreement provided with the
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* software.
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*/
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#include <dll/library.h>
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#define RETURN(R, B) \
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do \
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{ \
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if (0 != PResult) \
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*PResult = R; \
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return B; \
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} while (0,0)
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typedef struct
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{
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SRWLOCK Lock;
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ULONG Capacity, LoMark, HiMark;
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PUINT8 Buffer;
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} FSP_FILE_SYSTEM_DIRECTORY_BUFFER;
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static int FspFileSystemDirectoryBufferFileNameCmp(PWSTR a, int alen, PWSTR b, int blen)
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{
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int len, res;
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if (-1 == alen)
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alen = (int)lstrlenW(a);
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if (-1 == blen)
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blen = (int)lstrlenW(b);
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len = alen < blen ? alen : blen;
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/* order "." and ".." first */
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switch (alen)
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{
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case 1:
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if (L'.' == a[0])
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a = L"\1";
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break;
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case 2:
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if (L'.' == a[0] && L'.' == a[1])
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a = L"\1\1";
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break;
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}
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/* order "." and ".." first */
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switch (blen)
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{
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case 1:
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if (L'.' == b[0])
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b = L"\1";
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break;
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case 2:
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if (L'.' == b[0] && L'.' == b[1])
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b = L"\1\1";
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break;
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}
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res = invariant_wcsncmp(a, b, len);
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if (0 == res)
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res = alen - blen;
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return res;
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}
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/*
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* Binary search
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* "I wish I had the standard library!"
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*/
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static BOOLEAN FspFileSystemSearchDirectoryBuffer(FSP_FILE_SYSTEM_DIRECTORY_BUFFER *DirBuffer,
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PWSTR Marker, int MarkerLen, PULONG PIndexNum)
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{
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PULONG Index = (PULONG)(DirBuffer->Buffer + DirBuffer->HiMark);
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ULONG Count = (DirBuffer->Capacity - DirBuffer->HiMark) / sizeof(ULONG);
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FSP_FSCTL_DIR_INFO *DirInfo;
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int Lo = 0, Hi = Count - 1, Mi;
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int CmpResult;
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while (Lo <= Hi)
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{
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Mi = (unsigned)(Lo + Hi) >> 1;
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DirInfo = (PVOID)(DirBuffer->Buffer + Index[Mi]);
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CmpResult = FspFileSystemDirectoryBufferFileNameCmp(
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DirInfo->FileNameBuf, (DirInfo->Size - sizeof *DirInfo) / sizeof(WCHAR),
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Marker, MarkerLen);
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if (0 > CmpResult)
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Lo = Mi + 1;
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else if (0 < CmpResult)
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Hi = Mi - 1;
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else
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{
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*PIndexNum = Mi;
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return TRUE;
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}
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}
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*PIndexNum = Lo;
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return FALSE;
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}
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/*
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* Quick sort
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* "I wish I had the standard library!"
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*
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* Based on Sedgewick's Algorithms in C++; multiple editions.
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*
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* Implements a non-recursive quicksort with tail-end recursion eliminated
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* and median-of-three partitioning.
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*/
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#define less(a, b) FspFileSystemDirectoryBufferLess(Buffer, a, b)
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#define exch(a, b) { ULONG t = a; a = b; b = t; }
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#define compexch(a, b) if (less(b, a)) exch(a, b)
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#define push(i) (stack[stackpos++] = (i))
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#define pop() (stack[--stackpos])
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static __forceinline
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int FspFileSystemDirectoryBufferLess(PUINT8 Buffer, int a, int b)
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{
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FSP_FSCTL_DIR_INFO *DirInfoA = (FSP_FSCTL_DIR_INFO *)(Buffer + a);
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FSP_FSCTL_DIR_INFO *DirInfoB = (FSP_FSCTL_DIR_INFO *)(Buffer + b);
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return 0 > FspFileSystemDirectoryBufferFileNameCmp(
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DirInfoA->FileNameBuf, (DirInfoA->Size - sizeof *DirInfoA) / sizeof(WCHAR),
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DirInfoB->FileNameBuf, (DirInfoB->Size - sizeof *DirInfoB) / sizeof(WCHAR));
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}
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static __forceinline
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int FspFileSystemPartitionDirectoryBuffer(PUINT8 Buffer, PULONG Index, int l, int r)
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{
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int i = l - 1, j = r;
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ULONG v = Index[r];
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for (;;)
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{
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while (less(Index[++i], v))
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;
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while (less(v, Index[--j]))
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if (j == l)
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break;
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if (i >= j)
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break;
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exch(Index[i], Index[j]);
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}
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exch(Index[i], Index[r]);
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return i;
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}
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static VOID FspFileSystemQSortDirectoryBuffer(PUINT8 Buffer, PULONG Index, int l, int r)
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{
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int stack[64], stackpos = 0;
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int i;
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for (;;)
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{
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while (r > l)
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{
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#if 0
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exch(Index[(l + r) / 2], Index[r - 1]);
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compexch(Index[l], Index[r - 1]);
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compexch(Index[l], Index[r]);
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compexch(Index[r - 1], Index[r]);
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i = FspFileSystemPartitionDirectoryBuffer(Buffer, Index, l + 1, r - 1);
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#else
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i = FspFileSystemPartitionDirectoryBuffer(Buffer, Index, l, r);
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#endif
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if (i - l > r - i)
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{
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push(l); push(i - 1);
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l = i + 1;
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}
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else
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{
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push(i + 1); push(r);
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r = i - 1;
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}
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}
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if (0 == stackpos)
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break;
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r = pop(); l = pop();
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}
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}
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#undef push
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#undef pop
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#undef less
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#undef compexch
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#undef exch
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static inline VOID FspFileSystemSortDirectoryBuffer(FSP_FILE_SYSTEM_DIRECTORY_BUFFER *DirBuffer)
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{
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PUINT8 Buffer = DirBuffer->Buffer;
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PULONG Index = (PULONG)(DirBuffer->Buffer + DirBuffer->HiMark);
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ULONG Count = (DirBuffer->Capacity - DirBuffer->HiMark) / sizeof(ULONG);
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FspFileSystemQSortDirectoryBuffer(Buffer, Index, 0, Count - 1);
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}
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FSP_API BOOLEAN FspFileSystemAcquireDirectoryBuffer(PVOID *PDirBuffer,
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BOOLEAN Reset, PNTSTATUS PResult)
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{
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FSP_FILE_SYSTEM_DIRECTORY_BUFFER *DirBuffer = *PDirBuffer;
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MemoryBarrier();
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if (0 == DirBuffer)
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{
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static SRWLOCK CreateLock = SRWLOCK_INIT;
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FSP_FILE_SYSTEM_DIRECTORY_BUFFER *NewDirBuffer;
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NewDirBuffer = MemAlloc(sizeof *NewDirBuffer);
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if (0 == NewDirBuffer)
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RETURN(STATUS_INSUFFICIENT_RESOURCES, FALSE);
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memset(NewDirBuffer, 0, sizeof *NewDirBuffer);
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InitializeSRWLock(&NewDirBuffer->Lock);
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AcquireSRWLockExclusive(&NewDirBuffer->Lock);
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AcquireSRWLockExclusive(&CreateLock);
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DirBuffer = *PDirBuffer;
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MemoryBarrier();
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if (0 == DirBuffer)
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*PDirBuffer = DirBuffer = NewDirBuffer;
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ReleaseSRWLockExclusive(&CreateLock);
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if (DirBuffer == NewDirBuffer)
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RETURN(STATUS_SUCCESS, TRUE);
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ReleaseSRWLockExclusive(&NewDirBuffer->Lock);
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MemFree(NewDirBuffer);
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}
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if (Reset)
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{
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AcquireSRWLockExclusive(&DirBuffer->Lock);
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DirBuffer->LoMark = 0;
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DirBuffer->HiMark = DirBuffer->Capacity;
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RETURN(STATUS_SUCCESS, TRUE);
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}
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RETURN(STATUS_SUCCESS, FALSE);
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}
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FSP_API BOOLEAN FspFileSystemFillDirectoryBuffer(PVOID *PDirBuffer,
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FSP_FSCTL_DIR_INFO *DirInfo, PNTSTATUS PResult)
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{
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/* assume that FspFileSystemAcquireDirectoryBuffer has been called */
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FSP_FILE_SYSTEM_DIRECTORY_BUFFER *DirBuffer = *PDirBuffer;
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ULONG Capacity, LoMark, HiMark;
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PUINT8 Buffer;
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if (0 == DirInfo)
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RETURN(STATUS_INVALID_PARAMETER, FALSE);
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for (;;)
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{
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LoMark = DirBuffer->LoMark;
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HiMark = DirBuffer->HiMark;
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Buffer = DirBuffer->Buffer;
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if (FspFileSystemAddDirInfo(DirInfo,
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Buffer,
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HiMark > sizeof(ULONG) ? HiMark - sizeof(ULONG)/*space for new index entry*/ : HiMark,
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&LoMark))
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{
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HiMark -= sizeof(ULONG);
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*(PULONG)(Buffer + HiMark) = DirBuffer->LoMark;
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DirBuffer->LoMark = LoMark;
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DirBuffer->HiMark = HiMark;
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RETURN (STATUS_SUCCESS, TRUE);
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}
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if (0 == Buffer)
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{
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Buffer = MemAlloc(Capacity = 512);
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if (0 == Buffer)
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RETURN(STATUS_INSUFFICIENT_RESOURCES, FALSE);
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HiMark = Capacity;
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}
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else
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{
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Buffer = MemRealloc(Buffer, Capacity = DirBuffer->Capacity * 2);
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if (0 == Buffer)
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RETURN(STATUS_INSUFFICIENT_RESOURCES, FALSE);
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ULONG IndexSize = DirBuffer->Capacity - HiMark;
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ULONG NewHiMark = Capacity - IndexSize;
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memmove(Buffer + NewHiMark, Buffer + HiMark, IndexSize);
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HiMark = NewHiMark;
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}
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DirBuffer->Capacity = Capacity;
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DirBuffer->LoMark = LoMark;
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DirBuffer->HiMark = HiMark;
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DirBuffer->Buffer = Buffer;
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}
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}
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FSP_API VOID FspFileSystemReleaseDirectoryBuffer(PVOID *PDirBuffer)
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{
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/* assume that FspFileSystemAcquireDirectoryBuffer has been called */
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FSP_FILE_SYSTEM_DIRECTORY_BUFFER *DirBuffer = *PDirBuffer;
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FspFileSystemSortDirectoryBuffer(DirBuffer);
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ReleaseSRWLockExclusive(&DirBuffer->Lock);
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}
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FSP_API VOID FspFileSystemReadDirectoryBuffer(PVOID *PDirBuffer,
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PWSTR Marker,
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PVOID Buffer, ULONG Length, PULONG PBytesTransferred)
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{
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FSP_FILE_SYSTEM_DIRECTORY_BUFFER *DirBuffer = *PDirBuffer;
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MemoryBarrier();
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if (0 != DirBuffer)
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{
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AcquireSRWLockShared(&DirBuffer->Lock);
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PULONG Index = (PULONG)(DirBuffer->Buffer + DirBuffer->HiMark);
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ULONG Count = (DirBuffer->Capacity - DirBuffer->HiMark) / sizeof(ULONG);
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ULONG IndexNum;
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FSP_FSCTL_DIR_INFO *DirInfo;
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if (0 == Marker)
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IndexNum = 0;
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else
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{
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FspFileSystemSearchDirectoryBuffer(DirBuffer,
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Marker, lstrlenW(Marker),
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&IndexNum);
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IndexNum++;
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}
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for (; IndexNum < Count; IndexNum++)
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{
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DirInfo = (PVOID)(DirBuffer->Buffer + Index[IndexNum]);
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if (!FspFileSystemAddDirInfo(DirInfo, Buffer, Length, PBytesTransferred))
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{
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ReleaseSRWLockShared(&DirBuffer->Lock);
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return;
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}
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}
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ReleaseSRWLockShared(&DirBuffer->Lock);
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}
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FspFileSystemAddDirInfo(0, Buffer, Length, PBytesTransferred);
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}
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FSP_API VOID FspFileSystemDeleteDirectoryBuffer(PVOID *PDirBuffer)
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{
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FSP_FILE_SYSTEM_DIRECTORY_BUFFER *DirBuffer = *PDirBuffer;
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MemoryBarrier();
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if (0 != DirBuffer)
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{
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MemFree(DirBuffer->Buffer);
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MemFree(DirBuffer);
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*PDirBuffer = 0;
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}
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}
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