175 lines
3.9 KiB
C
175 lines
3.9 KiB
C
/*++
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Copyright (c) 1985 - 1999, Microsoft Corporation
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Module Name:
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share.c
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Abstract:
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Implements sharing for input and output handles
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Author:
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Therese Stowell (thereses) 11-Nov-1990
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Revision History:
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--*/
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#include "precomp.h"
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#pragma hdrstop
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NTSTATUS
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ConsoleAddShare(
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IN ACCESS_MASK DesiredAccess,
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IN ULONG DesiredShareAccess,
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IN OUT PCONSOLE_SHARE_ACCESS ShareAccess,
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IN OUT PHANDLE_DATA HandleData
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)
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{
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ULONG Ocount;
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ULONG ReadAccess;
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ULONG WriteAccess;
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ULONG SharedRead;
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ULONG SharedWrite;
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// Set the access type in the file object for the current accessor.
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ReadAccess = (DesiredAccess & GENERIC_READ) != 0;
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WriteAccess = (DesiredAccess & GENERIC_WRITE) != 0;
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SharedRead = (DesiredShareAccess & FILE_SHARE_READ) != 0;
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SharedWrite = (DesiredShareAccess & FILE_SHARE_WRITE) != 0;
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// Now check to see whether or not the desired accesses are compatible
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// with the way that the file is currently open.
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Ocount = ShareAccess->OpenCount;
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if ( (ReadAccess && (ShareAccess->SharedRead < Ocount))
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(WriteAccess && (ShareAccess->SharedWrite < Ocount))
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((ShareAccess->Readers != 0) && !SharedRead)
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((ShareAccess->Writers != 0) && !SharedWrite)
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) {
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// The check failed. Simply return to the caller indicating that the
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// current open cannot access the file.
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return STATUS_SHARING_VIOLATION;
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} else {
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// The check was successful. Update the counter information in the
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// shared access structure for this open request if the caller
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// specified that it should be updated.
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ShareAccess->OpenCount++;
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ShareAccess->Readers += ReadAccess;
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ShareAccess->Writers += WriteAccess;
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ShareAccess->SharedRead += SharedRead;
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ShareAccess->SharedWrite += SharedWrite;
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HandleData->Access = DesiredAccess;
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HandleData->ShareAccess = DesiredShareAccess;
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return STATUS_SUCCESS;
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}
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}
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NTSTATUS
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ConsoleDupShare(
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IN ACCESS_MASK DesiredAccess,
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IN ULONG DesiredShareAccess,
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IN OUT PCONSOLE_SHARE_ACCESS ShareAccess,
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IN OUT PHANDLE_DATA TargetHandleData
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)
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{
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ULONG ReadAccess;
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ULONG WriteAccess;
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ULONG SharedRead;
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ULONG SharedWrite;
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// Set the access type in the file object for the current accessor.
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ReadAccess = (DesiredAccess & GENERIC_READ) != 0;
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WriteAccess = (DesiredAccess & GENERIC_WRITE) != 0;
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SharedRead = (DesiredShareAccess & FILE_SHARE_READ) != 0;
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SharedWrite = (DesiredShareAccess & FILE_SHARE_WRITE) != 0;
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if (ShareAccess->OpenCount == 0) {
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ASSERT (FALSE);
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return STATUS_SHARING_VIOLATION;
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}
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ShareAccess->OpenCount++;
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ShareAccess->Readers += ReadAccess;
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ShareAccess->Writers += WriteAccess;
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ShareAccess->SharedRead += SharedRead;
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ShareAccess->SharedWrite += SharedWrite;
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TargetHandleData->Access = DesiredAccess;
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TargetHandleData->ShareAccess = DesiredShareAccess;
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return STATUS_SUCCESS;
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}
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NTSTATUS
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ConsoleRemoveShare(
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IN ULONG DesiredAccess,
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IN ULONG DesiredShareAccess,
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IN OUT PCONSOLE_SHARE_ACCESS ShareAccess
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)
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{
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ULONG ReadAccess;
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ULONG WriteAccess;
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ULONG SharedRead;
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ULONG SharedWrite;
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// Set the access type in the file object for the current accessor.
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ReadAccess = (DesiredAccess & GENERIC_READ) != 0;
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WriteAccess = (DesiredAccess & GENERIC_WRITE) != 0;
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SharedRead = (DesiredShareAccess & FILE_SHARE_READ) != 0;
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SharedWrite = (DesiredShareAccess & FILE_SHARE_WRITE) != 0;
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if (ShareAccess->OpenCount == 0) {
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ASSERT (FALSE);
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return STATUS_UNSUCCESSFUL;
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}
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ShareAccess->OpenCount--;
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ShareAccess->Readers -= ReadAccess;
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ShareAccess->Writers -= WriteAccess;
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ShareAccess->SharedRead -= SharedRead;
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ShareAccess->SharedWrite -= SharedWrite;
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return STATUS_SUCCESS;
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}
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