GP-5728 improve go pcheader and moduledata searching

These code paths are mainly hit with stripped PE binaries, and together
with the missing 1.20+ pcheader magic value would cause failure to find
the firstmoduledata struct, which is the root of everything.

Ghidra/Features/Base/src/main/java/ghidra/app/util/bin/format/golang/rtti/GoModuledata.java

@@ -472,17 +472,21 @@ public class GoModuledata implements StructureMarkup<GoModuledata> {
 		int ptrSize = context.getPtrSize();
 		byte[] searchBytes = new byte[ptrSize];
 		context.getDataConverter().putValue(pcHeaderAddress.getOffset(), ptrSize, searchBytes, 0);
-		Address moduleAddr = memory.findBytes(range.getMinAddress(), range.getMaxAddress(),
-			searchBytes, null, true, monitor);
-		if (moduleAddr == null) {
-			return null;
+
+		Address moduleAddr;
+		while ((moduleAddr = memory.findBytes(range.getMinAddress(), range.getMaxAddress(),
+			searchBytes, null, true, monitor)) != null) {
+
+			GoModuledata moduleData = context.readStructure(GoModuledata.class, moduleAddr);
+
+			// Verify that we read a good GoModuledata struct by comparing some of its values to
+			// the pclntab structure.
+			if (moduleData.matchesPcHeader(pcHeader)) {
+				return moduleData;
+			}
+			range = new AddressRangeImpl(moduleAddr.next(), range.getMaxAddress());
 		}
-
-		GoModuledata moduleData = context.readStructure(GoModuledata.class, moduleAddr);
-
-		// Verify that we read a good GoModuledata struct by comparing some of its values to
-		// the pclntab structure.
-		return moduleData.matchesPcHeader(pcHeader) ? moduleData : null;
+		return null;
 	}
 
 }

Ghidra/Features/Base/src/main/java/ghidra/app/util/bin/format/golang/rtti/GoPcHeader.java

@@ -20,8 +20,7 @@ import java.io.IOException;
 import ghidra.app.util.bin.*;
 import ghidra.app.util.bin.format.golang.GoVer;
 import ghidra.app.util.bin.format.golang.structmapping.*;
-import ghidra.program.model.address.Address;
-import ghidra.program.model.address.AddressRange;
+import ghidra.program.model.address.*;
 import ghidra.program.model.data.*;
 import ghidra.program.model.lang.Endian;
 import ghidra.program.model.listing.Program;
@@ -113,15 +112,18 @@ public class GoPcHeader {
 			(byte) 0xff // ptrSize 
 		};
 		Memory memory = programContext.getProgram().getMemory();
-		Address pcHeaderAddr = memory.findBytes(range.getMinAddress(), range.getMaxAddress(),
-			searchBytes, searchMask, true, monitor);
-		if (pcHeaderAddr == null) {
-			return null;
-		}
-		try (MemoryByteProvider bp =
-			new MemoryByteProvider(memory, pcHeaderAddr, range.getMaxAddress())) {
-			return isPcHeader(bp) ? pcHeaderAddr : null;
+		Address pcHeaderAddr;
+		while ((pcHeaderAddr = memory.findBytes(range.getMinAddress(), range.getMaxAddress(),
+			searchBytes, searchMask, true, monitor)) != null) {
+			try (MemoryByteProvider bp =
+				new MemoryByteProvider(memory, pcHeaderAddr, range.getMaxAddress())) {
+				if (isPcHeader(bp)) {
+					return pcHeaderAddr;
+				}
+			}
+			range = new AddressRangeImpl(pcHeaderAddr.next(), range.getMaxAddress());
 		}
+		return null;
 	}
 
 	/**
@@ -287,6 +289,10 @@ public class GoPcHeader {
 		return ptrSize;
 	}
 
+	public int getMagic() {
+		return magic;
+	}
+
 	//--------------------------------------------------------------------------------------------
 	record GoVerEndian(GoVer goVer, Endian endian) {
 		GoVerEndian(GoVer goVer, boolean isLittleEndian) {

Ghidra/Features/Base/src/main/java/ghidra/app/util/bin/format/golang/rtti/GoRttiMapper.java

@@ -507,6 +507,12 @@ public class GoRttiMapper extends DataTypeMapper implements DataTypeMapperContex
 					throw new IOException(
 						"Mismatched ptrSize: %d vs %d".formatted(pcHeader.getPtrSize(), ptrSize));
 				}
+				if (pcHeader.getGoVersion().isInvalid()) {
+					// we can get here if the firstmoduledata was located via symbolname instead of
+					// relying on bootstraping via the pcheader
+					Msg.warn(this,
+						"Unknown golang pcheader magic value: 0x%x".formatted(pcHeader.getMagic()));
+				}
 			}
 			addModule(firstModule);
 		}