hfs-522.100.5.tar.gz

[apple/hfs.git] / core / BTreeScanner.h

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+/*
+ * Copyright (c) 1996-2004 Apple Inc. All rights reserved.
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ * 
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
+ *
+ *     @(#)BTreeScanner.h
+ */
+
+#ifndef        _BTREESCANNER_H_
+#define _BTREESCANNER_H_
+
+#include <sys/appleapiopts.h>
+
+#ifdef KERNEL
+#ifdef __APPLE_API_PRIVATE
+#include <sys/time.h>
+
+#include "FileMgrInternal.h"
+#include "BTreesPrivate.h"
+
+// amount of time we are allowed to process a catalog search (in µ secs)
+// NOTE - code assumes kMaxMicroSecsInKernel is less than 1,000,000
+enum { kMaxMicroSecsInKernel = (1000 * 100) }; // 1 tenth of a second
+
+// btree node scanner buffer size.  at 32K we get 8 nodes.  this is the size used
+// in Mac OS 9
+enum { kCatSearchBufferSize = (32 * 1024) };
+
+
+/*
+ * ============ W A R N I N G ! ============
+ * DO NOT INCREASE THE SIZE OF THIS STRUCT!
+ * It must be less than or equal to the size of 
+ * the opaque searchstate struct (in sys/attr.h).
+ */
+/* Private description used in hfs_search */
+struct CatPosition 
+{
+  u_int32_t            writeCount;     /* The BTree's write count (to see if the catalog writeCount */
+                               /* changed since the last search).  If 0, the rest */
+                               /* of the record is invalid, start from beginning. */
+  u_int32_t     nextNode;      /* node number to resume search */
+  u_int32_t    nextRecord;     /* record number to resume search */
+  u_int32_t    recordsFound;   /* number of leaf records seen so far */
+};
+typedef struct CatPosition              CatPosition;
+
+
+/*
+       BTScanState - This structure is used to keep track of the current state
+       of a BTree scan.  It contains both the dynamic state information (like
+       the current node number and record number) and information that is static
+       for the duration of a scan (such as buffer pointers).
+       
+       NOTE: recordNum may equal or exceed the number of records in the node
+       number nodeNum.  If so, then the next attempt to get a record will move
+       to a new node number.
+*/
+struct BTScanState 
+{
+       //      The following fields are set up once at initialization time.
+       //      They are not changed during a scan.
+       u_int32_t                       bufferSize;
+       struct buf *            bufferPtr;
+       BTreeControlBlock *     btcb;
+       
+       //      The following fields are the dynamic state of the current scan.
+       u_int32_t                       nodeNum;                        // zero is first node
+       u_int32_t                       recordNum;                      // zero is first record
+       BTNodeDescriptor *      currentNodePtr;         // points to current node within buffer
+       u_int32_t                       nodesLeftInBuffer;      // number of valid nodes still in the buffer
+       u_int32_t                       recordsFound;           // number of leaf records seen so far
+       struct timeval          startTime;                      // time we started catalog search
+};
+typedef struct BTScanState BTScanState;
+
+
+/* *********************** PROTOTYPES *********************** */
+
+int    BTScanInitialize(       const FCB *             btreeFile,
+                                               u_int32_t               startingNode,
+                                               u_int32_t               startingRecord,
+                                               u_int32_t               recordsFound,
+                                               u_int32_t               bufferSize,
+                                               BTScanState     *       scanState     );
+                                                       
+int BTScanNextRecord(  BTScanState *   scanState,
+                                               Boolean                 avoidIO,
+                                               void * *                key,
+                                               void * *                data,
+                                               u_int32_t *             dataSize  );
+
+int    BTScanTerminate(        BTScanState *   scanState,
+                                               u_int32_t *             startingNode,
+                                               u_int32_t *             startingRecord,
+                                               u_int32_t *             recordsFound    );
+
+#endif /* __APPLE_API_PRIVATE */
+#endif /* KERNEL */
+#endif /* !_BTREESCANNER_H_ */