From 6e19466dc618a6fc916a58cd3efdb1c08b32bd36 Mon Sep 17 00:00:00 2001
From: Ryan Kurtz <ryanmkurtz@users.noreply.github.com>
Date: Fri, 19 Mar 2021 10:43:34 -0400
Subject: [PATCH] GP-786: Some improvements and docs for the PE and ELF
 exporters

---
 .../help/topics/ExporterPlugin/exporter.htm   |  30 +++-
 .../exporter/AbstractExecutableExporter.java  | 107 ------------
 .../util/exporter/AbstractLoaderExporter.java | 161 ++++++++++++++++++
 .../ghidra/app/util/exporter/ElfExporter.java |  18 +-
 .../ghidra/app/util/exporter/PeExporter.java  |  14 +-
 5 files changed, 216 insertions(+), 114 deletions(-)
 delete mode 100644 Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/AbstractExecutableExporter.java
 create mode 100644 Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/AbstractLoaderExporter.java

diff --git a/Ghidra/Features/Base/src/main/help/help/topics/ExporterPlugin/exporter.htm b/Ghidra/Features/Base/src/main/help/help/topics/ExporterPlugin/exporter.htm
index 1509a09ba1..4a8ff89bdd 100644
--- a/Ghidra/Features/Base/src/main/help/help/topics/ExporterPlugin/exporter.htm
+++ b/Ghidra/Features/Base/src/main/help/help/topics/ExporterPlugin/exporter.htm
@@ -284,6 +284,20 @@
             </LI>
           </UL>
         </BLOCKQUOTE>
+        
+        <H3><A name="elf"></A>ELF</H3>
+
+        <BLOCKQUOTE>
+          <P>Writes an ELF program that was imported with the ELF loader back to its original file 
+          layout. Any file-backed bytes that were modified by the user in the program database will 
+          be reflected in the new file.</P>
+
+          <P><IMG alt="" border="0" src="../../shared/note.png"> <I>Writing back a modified Memory 
+          Map is not supported. </I></P>
+          
+          <P><IMG alt="" border="0" src="../../shared/note.png"> <I>Relocation bytes are always
+          restored to their original values, even if the user modifies them.</I></P>
+        </BLOCKQUOTE>
 
         <H3><A name="gzf"></A>Ghidra Zip File (.gzf)</H3>
 
@@ -320,7 +334,7 @@
 
           <UL>
             <LI><B>Address Space</B> - Specifies which address space to export as Intel Hex format
-            only supports one address space. This option will be intialized to the "default"
+            only supports one address space. This option will be initialized to the "default"
             address space.</LI>
             <LI><B>Record Size</B> - Specifies the size (in bytes) of each record in the
             output file. The default 16.</LI>
@@ -330,6 +344,20 @@
             2 bytes will be dropped.</LI>
           </UL>
         </BLOCKQUOTE>
+        
+        <H3><A name="pe"></A>PE</H3>
+
+        <BLOCKQUOTE>
+          <P>Writes a PE program that was imported with the PE loader back to its original file 
+          layout. Any file-backed bytes that were modified by the user in the program database will 
+          be reflected in the new file.</P>
+
+          <P><IMG alt="" border="0" src="../../shared/note.png"> <I>Writing back a modified Memory 
+          Map is not supported. </I></P>
+          
+          <P><IMG alt="" border="0" src="../../shared/note.png"> <I>Relocation bytes are always
+          restored to their original values, even if the user modifies them.</I></P>
+        </BLOCKQUOTE>
 
         <H3><A name="xml"/><A name="Options_XML"/>XML</H3>
 
diff --git a/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/AbstractExecutableExporter.java b/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/AbstractExecutableExporter.java
deleted file mode 100644
index 490bfda798..0000000000
--- a/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/AbstractExecutableExporter.java
+++ /dev/null
@@ -1,107 +0,0 @@
-/* ###
- * 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.exporter;
-
-import java.io.*;
-import java.util.List;
-import java.util.Optional;
-
-import ghidra.app.script.GhidraScript;
-import ghidra.app.util.DomainObjectService;
-import ghidra.app.util.Option;
-import ghidra.framework.model.DomainObject;
-import ghidra.program.database.mem.AddressSourceInfo;
-import ghidra.program.database.mem.FileBytes;
-import ghidra.program.model.address.*;
-import ghidra.program.model.listing.Program;
-import ghidra.program.model.mem.*;
-import ghidra.program.model.reloc.Relocation;
-import ghidra.util.HelpLocation;
-import ghidra.util.task.TaskMonitor;
-import utilities.util.FileUtilities;
-
-abstract class AbstractExecutableExporter extends Exporter {
-
-	protected AbstractExecutableExporter(String name, String extension, HelpLocation help) {
-		super(name, extension, help);
-	}
-
-	@Override
-	public boolean export(File file, DomainObject domainObj, AddressSetView addrSet,
-			TaskMonitor monitor) throws IOException, ExporterException {
-
-		if (!(domainObj instanceof Program)) {
-			log.appendMsg("Unsupported type: " + domainObj.getClass().getName());
-			return false;
-		}
-		Program program = (Program) domainObj;
-		Memory memory = program.getMemory();
-
-		try (OutputStream out = new FileOutputStream(file, false)) {
-			FileBytes[] fileBytes = memory.getAllFileBytes()
-				.stream()
-				.filter((fb) -> fb.getFilename().equals(program.getName()))
-				.toArray(FileBytes[]::new);
-			for (FileBytes bytes : fileBytes) {
-				FileBytesInputStream byteStream = new FileBytesInputStream(bytes);
-				FileUtilities.copyStreamToStream(byteStream, out, monitor);
-			}
-		}
-		try (RandomAccessFile fout = new RandomAccessFile(file, "rw")) {
-				Iterable<Relocation> relocs =
-					() -> program.getRelocationTable().getRelocations();
-				for (Relocation reloc : relocs) {
-					AddressSourceInfo info = memory.getAddressSourceInfo(reloc.getAddress());
-					// some relocations report negative offsets
-					if (info.getFileOffset() >= 0) {
-						// seek incase we are larger than an int
-						fout.seek(info.getFileOffset());
-						fout.write(reloc.getBytes());
-					}
-				}
-			}
-
-		return true;
-	}
-
-	@Override
-	public List<Option> getOptions(DomainObjectService domainObjectService) {
-		return EMPTY_OPTIONS;
-	}
-
-	@Override
-	public void setOptions(List<Option> options) {
-	}
-
-	private static class FileBytesInputStream extends InputStream {
-
-		private long pos = 0;
-		private final FileBytes bytes;
-
-		FileBytesInputStream(FileBytes bytes) {
-			this.bytes = bytes;
-		}
-
-		@Override
-		public int read() throws IOException {
-			if (pos < bytes.getSize()) {
-				return bytes.getModifiedByte(pos++) & 0xff;
-			}
-			return -1;
-		}
-
-	}
-}
diff --git a/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/AbstractLoaderExporter.java b/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/AbstractLoaderExporter.java
new file mode 100644
index 0000000000..d2ac9c6187
--- /dev/null
+++ b/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/AbstractLoaderExporter.java
@@ -0,0 +1,161 @@
+/* ###
+ * 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.exporter;
+
+import java.io.*;
+import java.util.List;
+
+import ghidra.app.util.DomainObjectService;
+import ghidra.app.util.Option;
+import ghidra.app.util.opinion.Loader;
+import ghidra.framework.model.DomainObject;
+import ghidra.program.database.mem.AddressSourceInfo;
+import ghidra.program.database.mem.FileBytes;
+import ghidra.program.model.address.AddressSetView;
+import ghidra.program.model.listing.Program;
+import ghidra.program.model.mem.Memory;
+import ghidra.program.model.reloc.Relocation;
+import ghidra.util.Conv;
+import ghidra.util.HelpLocation;
+import ghidra.util.task.TaskMonitor;
+import utilities.util.FileUtilities;
+
+/**
+ * An {@link Exporter} that can export programs imported with a particular {@link Loader}
+ */
+abstract class AbstractLoaderExporter extends Exporter {
+
+	/**
+	 * Creates a new {@link AbstractLoaderExporter}
+	 * 
+	 * @param name The display name of this exporter
+	 * @param extension The default extension for this exporter
+	 * @param help The {@link HelpLocation} for this exporter
+	 */
+	protected AbstractLoaderExporter(String name, String extension, HelpLocation help) {
+		super(name, extension, help);
+	}
+	
+	/**
+	 * Checks to see if the given file format is supported by this exporter
+	 * 
+	 * @param fileFormat The file format (loader name) of the program to export
+	 * @return True if the given file format is supported by this exporter; otherwise, false
+	 */
+	protected abstract boolean supportsFileFormat(String fileFormat); 
+
+	@Override
+	public boolean export(File file, DomainObject domainObj, AddressSetView addrSet,
+			TaskMonitor monitor) throws IOException, ExporterException {
+
+		if (!(domainObj instanceof Program)) {
+			log.appendMsg("Unsupported type: " + domainObj.getClass().getSimpleName());
+			return false;
+		}
+		
+		Program program = (Program) domainObj;
+		Memory memory = program.getMemory();
+		
+		String fileFormat = program.getExecutableFormat();
+		if (!supportsFileFormat(fileFormat)) {
+			log.appendMsg("Unsupported file format: " + fileFormat);
+			return false;
+		}
+
+		// Write source program's file bytes to the file 
+		try (OutputStream out = new FileOutputStream(file, false)) {
+			FileBytes[] fileBytes = memory.getAllFileBytes()
+					.stream()
+					.filter(fb -> program.getExecutablePath().endsWith(fb.getFilename()))
+					.toArray(FileBytes[]::new);
+			for (FileBytes bytes : fileBytes) {
+				FileUtilities.copyStreamToStream(new FileBytesInputStream(bytes), out, monitor);
+			}
+		}
+		
+		// Undo relocations in the file
+		String error = null;
+		try (RandomAccessFile fout = new RandomAccessFile(file, "rw")) {
+			Iterable<Relocation> relocs = () -> program.getRelocationTable().getRelocations();
+			for (Relocation reloc : relocs) {
+				AddressSourceInfo info = memory.getAddressSourceInfo(reloc.getAddress());
+				if (info == null) {
+					error = "Failed to get relocation address source";
+					break;
+				}
+				if (info.getFileOffset() < 0) {
+					error = "Failed to get relocation file offset";
+					break;
+				}
+				if (info.getFileOffset() >= fout.length()) {
+					error = "Relocation file offset exceeds file length";
+					break;
+				}
+				fout.seek(info.getFileOffset());
+				fout.write(reloc.getBytes());
+			}
+		}
+		
+		// If errors occurred, log them and clean up the corrupted file
+		if (error != null) {
+			log.appendMsg(error);
+			if (!file.delete()) {
+				log.appendMsg("Failed to delete corrupted file: " + file);
+			}
+			return false;
+		}
+
+		return true;
+	}
+
+	@Override
+	public List<Option> getOptions(DomainObjectService domainObjectService) {
+		return EMPTY_OPTIONS;
+	}
+
+	@Override
+	public void setOptions(List<Option> options) {
+		// No options
+	}
+
+	/**
+	 * An {@link InputStream} that reads a {@link FileBytes} modified bytes
+	 */
+	private static class FileBytesInputStream extends InputStream {
+
+		private final FileBytes fileBytes;
+		private long size;
+		private long pos;
+
+		/**
+		 * Creates a new {@link InputStream} that can read over the modified bytes of the given
+		 * {@link FileBytes} object
+		 * 
+		 * @param fileBytes The {@link FileBytes} to use for the {@link InputStream}
+		 */
+		FileBytesInputStream(FileBytes fileBytes) {
+			this.fileBytes = fileBytes;
+			this.size = fileBytes.getSize();
+			this.pos = 0;
+		}
+
+		@Override
+		public int read() throws IOException {
+			return pos < size ? Conv.byteToInt(fileBytes.getModifiedByte(pos++)) : -1;
+		}
+
+	}
+}
diff --git a/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/ElfExporter.java b/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/ElfExporter.java
index 2b0a060cf1..93ed5b541e 100644
--- a/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/ElfExporter.java
+++ b/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/ElfExporter.java
@@ -15,13 +15,23 @@
  */
 package ghidra.app.util.exporter;
 
+import ghidra.app.util.opinion.ElfLoader;
 import ghidra.util.HelpLocation;
 
-// TODO export labels and other useful analysis information
-public class ElfExporter extends AbstractExecutableExporter {
+/**
+ * An {@link Exporter} that can export programs imported with the {@link ElfLoader}
+ */
+public class ElfExporter extends AbstractLoaderExporter {
 
+	/**
+	 * Create a new {@link ElfExporter}
+	 */
 	public ElfExporter() {
-		super("Elf", "", new HelpLocation("ExporterPlugin", "elf"));
+		super("ELF", "", new HelpLocation("ExporterPlugin", "elf"));
+	}
+	
+	@Override
+	protected boolean supportsFileFormat(String fileFormat) {
+		return ElfLoader.ELF_NAME.equals(fileFormat);
 	}
-
 }
diff --git a/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/PeExporter.java b/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/PeExporter.java
index be1c78b28b..8d4c299132 100644
--- a/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/PeExporter.java
+++ b/Ghidra/Features/Base/src/main/java/ghidra/app/util/exporter/PeExporter.java
@@ -15,13 +15,23 @@
  */
 package ghidra.app.util.exporter;
 
+import ghidra.app.util.opinion.PeLoader;
 import ghidra.util.HelpLocation;
 
-// TODO export labels and other useful analysis information
-public class PeExporter extends AbstractExecutableExporter {
+/**
+ * An {@link Exporter} that can export programs imported with the {@link PeLoader}
+ */
+public class PeExporter extends AbstractLoaderExporter {
 
+	/**
+	 * Creates a new {@link PeExporter}
+	 */
 	public PeExporter() {
 		super("PE", "exe", new HelpLocation("ExporterPlugin", "pe"));
 	}
 
+	@Override
+	protected boolean supportsFileFormat(String fileFormat) {
+		return PeLoader.PE_NAME.equals(fileFormat);
+	}
 }