GP-4743 - PDB - Developer stream and offset locator for file offset

Ghidra/Features/PDB/src/main/java/ghidra/app/util/bin/format/pdb2/pdbreader/AbstractPdb.java

@@ -20,8 +20,7 @@ import java.io.Writer;
 import java.util.ArrayList;
 import java.util.List;
 
-import ghidra.app.util.bin.format.pdb2.pdbreader.msf.Msf;
-import ghidra.app.util.bin.format.pdb2.pdbreader.msf.MsfStream;
+import ghidra.app.util.bin.format.pdb2.pdbreader.msf.*;
 import ghidra.app.util.bin.format.pdb2.pdbreader.symbol.AbstractMsSymbol;
 import ghidra.app.util.bin.format.pdb2.pdbreader.type.AbstractMsType;
 import ghidra.app.util.datatype.microsoft.GUID;
@@ -469,6 +468,35 @@ public abstract class AbstractPdb implements AutoCloseable {
 		return msf.getMonitor();
 	}
 
+	/**
+	 * Developer mechanism to locate stream and offset within that stream that is associated with
+	 * the given absolute file offset
+	 * @param fileOffset the absolute file offset that we are trying to locate
+	 * @return the stream and offset or {@code null} if not located
+	 */
+	public StreamAndOffset getStreamOffsetForAbsoluteFileOffset(long fileOffset) {
+		if (msf instanceof AbstractMsf myMsf) {
+			return myMsf.getStreamOffsetForAbsoluteFileOffset(fileOffset);
+		}
+		return null;
+	}
+
+	/**
+	 * Developer mechanism to get a {@code PdbByteReader} for the particular stream, offset, and
+	 * length.
+	 * @param streamNumber the stream number
+	 * @param offset the offset in the stream
+	 * @param length the number of bytes to include from the stream
+	 * @return the reader
+	 * @throws CancelledException upon user cancellation
+	 * @throws IOException upon issue getting the stream for the PDB
+	 */
+	public PdbByteReader getDeveloperBytes(int streamNumber, int offset, int length)
+			throws CancelledException, IOException {
+		PdbByteReader reader = getReaderForStreamNumber(streamNumber, offset, length);
+		return reader;
+	}
+
 	/**
 	 * Check to see if this monitor has been canceled
 	 * @throws CancelledException if monitor has been cancelled

Ghidra/Features/PDB/src/main/java/ghidra/app/util/bin/format/pdb2/pdbreader/msf/AbstractMsf.java

@@ -238,6 +238,26 @@ public abstract class AbstractMsf implements Msf {
 		}
 	}
 
+	/**
+	 * Developer mechanism to locate stream and offset within the stream that contains the
+	 * absolute file offset
+	 * @param fileOffset the absolute file offset that we are trying to locate
+	 * @return the offset in the stream of the file offset or {@code null} if not in the stream
+	 */
+	public StreamAndOffset getStreamOffsetForAbsoluteFileOffset(long fileOffset) {
+		if (fileOffset < 0L || fileOffset > (long) numPages * pageSize) {
+			return null;
+		}
+		for (int number = 0; number < streamTable.getNumStreams(); number++) {
+			MsfStream s = getStream(number);
+			Integer offset = s.getStreamOffsetForAbsoluteFileOffset(fileOffset);
+			if (offset != null) {
+				return new StreamAndOffset(number, offset);
+			}
+		}
+		return null;
+	}
+
 	//==============================================================================================
 	// Class Internals
 	//==============================================================================================

Ghidra/Features/PDB/src/main/java/ghidra/app/util/bin/format/pdb2/pdbreader/msf/MsfStream.java

@@ -72,8 +72,7 @@ public class MsfStream {
 	 *  inability to read required bytes
 	 * @throws CancelledException upon user cancellation
 	 */
-	public byte[] read(int streamOffset, int numToRead)
-			throws IOException, CancelledException {
+	public byte[] read(int streamOffset, int numToRead) throws IOException, CancelledException {
 		if (numToRead <= 0) {
 			return null;
 		}
@@ -231,12 +230,10 @@ public class MsfStream {
 	 * @throws PdbException upon not enough data left to parse
 	 * @throws CancelledException upon user cancellation
 	 */
-	void deserializePageNumbers(PdbByteReader reader)
-			throws PdbException, CancelledException {
+	void deserializePageNumbers(PdbByteReader reader) throws PdbException, CancelledException {
 		// This calculations works fine for streamLength = 0
 		//  and even streamLength = -1 (0xffffffff).
-		int numPages =
-			Msf.floorDivisionWithLog2Divisor(streamLength, msf.getLog2PageSize());
+		int numPages = Msf.floorDivisionWithLog2Divisor(streamLength, msf.getLog2PageSize());
 		if (msf.getPageNumberSize() == 2) {
 			for (int i = 0; i < numPages; i++) {
 				msf.checkCancelled();
@@ -276,4 +273,27 @@ public class MsfStream {
 		deserializePageNumbers(reader);
 	}
 
+	/**
+	 * Developer mechanism to see if the stream hold the absolute file offset and what the
+	 *  corresponding stream offset is
+	 * @param fileOffset the absolute file offset that we are trying to locate
+	 * @return the offset in the stream of the file offset or {@code null} if not in the stream
+	 */
+	Integer getStreamOffsetForAbsoluteFileOffset(long fileOffset) {
+		long pageSize = msf.getPageSize();
+		for (int pageCount = 0; pageCount < pageList.size(); pageCount++) {
+			int page = pageList.get(pageCount);
+			long pageStart = page * pageSize;
+			long pageEndExclusive = pageStart + pageSize;
+			if (pageStart <= fileOffset && fileOffset < pageEndExclusive) {
+				// We must get the offset within page, but then must use the pageCount to determine
+				// the rest of the streamOffset
+				Long pageOffset = fileOffset - pageStart;
+				Long streamOffset = pageCount * pageSize + pageOffset;
+				return streamOffset.intValue();
+			}
+		}
+		return null;
+	}
+
 }

Ghidra/Features/PDB/src/main/java/ghidra/app/util/bin/format/pdb2/pdbreader/msf/StreamAndOffset.java

@@ -0,0 +1,18 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.util.bin.format.pdb2.pdbreader.msf;
+
+public record StreamAndOffset(int number, int offset) {}