Add rebuild support for VersionInfo related structures

README.md

@@ -48,6 +48,7 @@ import com.kichik.pecoff4j.constant.ResourceType;
 import com.kichik.pecoff4j.io.DataReader;
 import com.kichik.pecoff4j.io.PEParser;
 import com.kichik.pecoff4j.resources.StringFileInfo;
+import com.kichik.pecoff4j.resources.StringPair;
 import com.kichik.pecoff4j.resources.StringTable;
 import com.kichik.pecoff4j.resources.VersionInfo;
 import com.kichik.pecoff4j.util.ResourceHelper;
@@ -64,11 +65,9 @@ public class Main {
 			VersionInfo version = VersionInfo.read(new DataReader(data));
 
 			StringFileInfo strings = version.getStringFileInfo();
-			StringTable table = strings.getTable(0);
-			for (int j = 0; j < table.getCount(); j++) {
-				String key = table.getString(j).getKey();
-				String value = table.getString(j).getValue();
-				System.out.println(key + " = " + value);
+			StringTable table = strings.getTables().get(0);
+			for (List<StringPair> pair :table.getStrings()){
+				System.out.println(pair.getKey() + " = " + pair.getValue());
 			}
 		}
 	}

src/main/java/com/kichik/pecoff4j/RebuildableStructure.java

@@ -0,0 +1,27 @@
+package com.kichik.pecoff4j;
+
+import com.kichik.pecoff4j.io.IDataWriter;
+
+import java.io.IOException;
+
+/**
+ * A structure that contains values derived from its content like lengths, checksums or pointers to nested structures.
+ *
+ * Use {@link #rebuild()} to update these values prior to {@link #write(IDataWriter)}. The latter just stores the values
+ * as they are present.
+ */
+public interface RebuildableStructure {
+    /**
+     * Update derived values such as lengths, checksums, serialized layout etc.
+     *
+     * @return the updated length of this structure in bytes (might include padding)
+     */
+    int rebuild();
+
+    /**
+     * Write this structure to a data writer.
+     *
+     * @param dw the writer
+     */
+    void write(IDataWriter dw) throws IOException;
+}

src/main/java/com/kichik/pecoff4j/resources/StringFileInfo.java

@@ -14,17 +14,32 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import com.kichik.pecoff4j.RebuildableStructure;
 import com.kichik.pecoff4j.io.IDataReader;
 import com.kichik.pecoff4j.io.IDataWriter;
 import com.kichik.pecoff4j.util.Strings;
 
-public class StringFileInfo {
+import static com.kichik.pecoff4j.util.Alignment.alignDword;
+
+/**
+ * File information structure.
+ *
+ * See <a href="https://learn.microsoft.com/en-us/windows/win32/menurc/stringfileinfo">StringFileInfo structure</a> for details.
+ */
+public class StringFileInfo implements RebuildableStructure {
+	/** The length of this structure (in bytes) */
 	private int length;
+
+	/** Always 0 */
 	private int valueLength;
+
+	/** 1 for text data, 0 for binary data */
 	private int type;
+
+	/** Must be "StringFileInfo" */
 	private String key;
-	private int padding;
-	private List<StringTable> tables = new ArrayList<StringTable>();
+
+	private final List<StringTable> tables = new ArrayList<>();
 
 	public static StringFileInfo read(IDataReader dr) throws IOException {
 		int initialPos = dr.getPosition();
@@ -35,10 +50,11 @@ public static StringFileInfo read(IDataReader dr) throws IOException {
 		sfi.setValueLength(dr.readWord());
 		sfi.setType(dr.readWord());
 		sfi.setKey(dr.readUnicode());
-		sfi.setPadding(dr.align(4));
+		dr.align(4);
 
-		while (dr.getPosition() - initialPos < sfi.getLength())
+		while (dr.getPosition() - initialPos < sfi.getLength()) {
 			sfi.add(StringTable.read(dr));
+		}
 
 		return sfi;
 	}
@@ -50,24 +66,36 @@ public static StringFileInfo readPartial(IDataReader dr, int initialPos, int len
 		sfi.setValueLength(valueLength);
 		sfi.setType(type);
 		sfi.setKey(key);
-		sfi.setPadding(dr.align(4));
+		dr.align(4);
 		while (dr.getPosition() - initialPos < sfi.getLength()) {
 			sfi.add(StringTable.read(dr));
 		}
 		return sfi;
 	}
 
+	@Override
+	public int rebuild() {
+		valueLength = 0;
+
+		int sum = alignDword(6 + Strings.getUtf16Length(key));
+		for (StringTable table : tables) {
+			sum += table.rebuild();
+		}
+		length = sum;
+		return length;
+	}
+
+	@Override
 	public void write(IDataWriter dw) throws IOException {
-		dw.writeWord(getLength());
-		if (getLength() == 0) {
+		dw.writeWord(length);
+		if (length == 0) {
 			return;
 		}
-		dw.writeWord(getValueLength());
-		dw.writeWord(getType());
-		dw.writeUnicode(getKey());
+		dw.writeWord(valueLength);
+		dw.writeWord(type);
+		dw.writeUnicode(key);
 		dw.align(4);
-		for (int i = 0; i < getCount(); i++) {
-			StringTable table = getTable(i);
+		for (StringTable table : tables) {
 			table.write(dw);
 		}
 	}
@@ -84,6 +112,10 @@ public StringTable getTable(int index) {
 		return tables.get(index);
 	}
 
+	public List<StringTable> getTables() {
+		return tables;
+	}
+
 	public int getLength() {
 		return length;
 	}
@@ -116,18 +148,11 @@ public void setKey(String key) {
 		this.key = key;
 	}
 
-	public int getPadding() {
-		return padding;
-	}
-
-	public void setPadding(int padding) {
-		this.padding = padding;
-	}
-
 	public int sizeOf() {
-		int actualLength = 6 + padding + Strings.getUtf16Length(key);
-		for (StringTable t : tables)
+		int actualLength = alignDword(6 + Strings.getUtf16Length(key));
+		for (StringTable t : tables) {
 			actualLength += t.sizeOf();
+		}
 		return actualLength;
 	}
 }

src/main/java/com/kichik/pecoff4j/resources/StringPair.java

@@ -10,20 +10,32 @@
  *******************************************************************************/
 package com.kichik.pecoff4j.resources;
 
+import com.kichik.pecoff4j.RebuildableStructure;
 import com.kichik.pecoff4j.io.IDataReader;
 import com.kichik.pecoff4j.io.IDataWriter;
 import com.kichik.pecoff4j.util.Reflection;
 import com.kichik.pecoff4j.util.Strings;
 
 import java.io.IOException;
 
-public class StringPair {
+import static com.kichik.pecoff4j.util.Alignment.*;
+
+/**
+ * A string pair.
+ *
+ * See <a href="https://learn.microsoft.com/en-us/windows/win32/menurc/string-str">String structure</a> for details.
+ */
+public class StringPair implements RebuildableStructure {
+	/** The length of this structure (in bytes) */
 	private int length;
+
+	/** The length of this value String (in words) */
 	private int valueLength;
+
+	/** 1 for text data, 0 for binary data */
 	private int type;
 	private String key;
 	private String value;
-	private int padding;
 
 	public static StringPair read(IDataReader dr) throws IOException {
 		int initialPos = dr.getPosition();
@@ -33,40 +45,60 @@ public static StringPair read(IDataReader dr) throws IOException {
 		sp.setValueLength(dr.readWord());
 		sp.setType(dr.readWord());
 		sp.setKey(dr.readUnicode());
-		sp.setPadding(dr.align(4));
+		dr.align(4);
 
 		int remainingWords = (sp.getLength() - (dr.getPosition() - initialPos)) / 2;
 		int valueLength = sp.getValueLength();
-		if (sp.getType() == 0) // wType == 0 => binary; wLength is in bytes
+		if (sp.getType() == 0) { // wType == 0 => binary; wLength is in bytes
 			valueLength /= 2;
-		if (valueLength > remainingWords)
+		}
+		if (valueLength > remainingWords) {
 			valueLength = remainingWords;
-		sp.setValue(dr.readUnicode(valueLength).trim());
+		}
+		sp.setValue(dr.readUnicode(valueLength - 1));
 
 		int remainingBytes = (sp.getLength() - (dr.getPosition() - initialPos));
 		dr.skipBytes(remainingBytes);
 		dr.align(4);
 		return sp;
 	}
 
+	@Override
+	public int rebuild() {
+		if (value.isEmpty()) {
+			// sometimes single null-byte is stored, so valueLength could also be 1 or 2 (depending on type)
+			valueLength = 0;
+		}
+		else if (type == 0) { // wType == 0 => binary; wLength is in bytes
+			valueLength = Strings.getUtf16Length(value);
+		} else {
+			valueLength = Strings.getUtf16Length(value) / 2;
+		}
+		length = sizeOf();
+		return length;
+	}
+
+	@Override
 	public void write(IDataWriter dw) throws IOException {
 		int initialPos = dw.getPosition();
 
-		dw.writeWord(getLength());
-		dw.writeWord(getValueLength());
-		dw.writeWord(getType());
-		dw.writeUnicode(getKey());
+		dw.writeWord(length);
+		dw.writeWord(valueLength);
+		dw.writeWord(type);
+		dw.writeUnicode(key);
 		dw.align(4);
 
-		int remainingWords = (getLength() - (dw.getPosition() - initialPos)) / 2;
-		int valueLength = getValueLength();
-		if (getType() == 0) // wType == 0 => binary; wLength is in bytes
-			valueLength /= 2;
-		if (valueLength > remainingWords)
-			valueLength = remainingWords;
-		dw.writeUnicode(getValue(), valueLength);
-
-		int remainingBytes = (getLength() - (dw.getPosition() - initialPos));
+		int remainingWords = (length - (dw.getPosition() - initialPos)) / 2;
+		int valueLengthInBytes = valueLength;
+		if (getType() == 0) {// wType == 0 => binary; wLength is in bytes
+			valueLengthInBytes /= 2;
+		}
+		if (valueLengthInBytes > remainingWords) {
+			valueLengthInBytes = remainingWords;
+		}
+		dw.writeUnicode(value, valueLengthInBytes);
+
+		int remainingBytes = (length - (dw.getPosition() - initialPos));
 		dw.writeByte(0, remainingBytes);
 		dw.align(4);
 	}
@@ -117,15 +149,8 @@ public String toString() {
 	}
 
 	public int sizeOf() {
-		return 6 + padding + Strings.getUtf16Length(key)
-				+ Strings.getUtf16Length(value);
+		return alignDword(6 + Strings.getUtf16Length(key))
+				+ (value.isEmpty() ? 0 : Strings.getUtf16Length(value));
 	}
 
-	public int getPadding() {
-		return padding;
-	}
-
-	public void setPadding(int padding) {
-		this.padding = padding;
-	}
 }