4 files changed, 83 insertions, 13 deletions

diff --git a/tools/gbagfx/lz.c b/tools/gbagfx/lz.c
index 7669dab9a..c2ba3e327 100644
--- a/tools/gbagfx/lz.c
+++ b/tools/gbagfx/lz.c
@@ -8,28 +8,28 @@
 unsigned char *LZDecompress(unsigned char *src, int srcSize, int *uncompressedSize)
 {
 	if (srcSize < 4)
-		return NULL;
+		goto fail;
 
 	int destSize = (src[3] << 16) | (src[2] << 8) | src[1];
 
 	unsigned char *dest = malloc(destSize);
 
 	if (dest == NULL)
-		return NULL;
+		goto fail;
 
 	int srcPos = 4;
 	int destPos = 0;
 
 	for (;;) {
 		if (srcPos >= srcSize)
-			return NULL;
+			goto fail;
 
 		unsigned char flags = src[srcPos++];
 
 		for (int i = 0; i < 8; i++) {
 			if (flags & 0x80) {
 				if (srcPos + 1 >= srcSize)
-					return NULL;
+					goto fail;
 
 				int blockSize = (src[srcPos] >> 4) + 3;
 				int blockDistance = (((src[srcPos] & 0xF) << 8) | src[srcPos + 1]) + 1;
@@ -38,14 +38,20 @@ unsigned char *LZDecompress(unsigned char *src, int srcSize, int *uncompressedSi
 
 				int blockPos = destPos - blockDistance;
 
-				if (destPos + blockSize > destSize || blockPos < 0)
-					return NULL;
+				// Some Ruby/Sapphire tilesets overflow.
+				if (destPos + blockSize > destSize) {
+					blockSize = destSize - destPos;
+					fprintf(stderr, "Destination buffer overflow.\n");
+				}
+
+				if (blockPos < 0)
+					goto fail;
 
 				for (int j = 0; j < blockSize; j++)
 					dest[destPos++] = dest[blockPos + j];
 			} else {
 				if (srcPos >= srcSize || destPos >= destSize)
-					return NULL;
+					goto fail;
 
 				dest[destPos++] = src[srcPos++];
 			}
@@ -58,6 +64,9 @@ unsigned char *LZDecompress(unsigned char *src, int srcSize, int *uncompressedSi
 			flags <<= 1;
 		}
 	}
+
+fail:
+	FATAL_ERROR("Fatal error while decompressing LZ file.\n");
 }
 
 unsigned char *LZCompress(unsigned char *src, int srcSize, int *compressedSize)
@@ -65,7 +74,7 @@ unsigned char *LZCompress(unsigned char *src, int srcSize, int *compressedSize)
 	const int minDistance = 2; // for compatibility with LZ77UnCompVram()
 
 	if (srcSize <= 0)
-		return NULL;
+		goto fail;
 
 	int worstCaseDestSize = 4 + srcSize + ((srcSize + 7) / 8);
 
@@ -75,7 +84,7 @@ unsigned char *LZCompress(unsigned char *src, int srcSize, int *compressedSize)
 	unsigned char *dest = malloc(worstCaseDestSize);
 
 	if (dest == NULL)
-		return NULL;
+		goto fail;
 
 	// header
 	dest[0] = 0x10; // LZ compression type
@@ -140,4 +149,7 @@ unsigned char *LZCompress(unsigned char *src, int srcSize, int *compressedSize)
 			}
 		}
 	}
+
+fail:
+	FATAL_ERROR("Fatal error while compressing LZ file.\n");
 }
diff --git a/tools/gbagfx/main.c b/tools/gbagfx/main.c
index 065967a11..e33e061b2 100644
--- a/tools/gbagfx/main.c
+++ b/tools/gbagfx/main.c
@@ -228,13 +228,44 @@ void HandlePngToFullwidthJapaneseFontCommand(char *inputPath, char *outputPath,
 	FreeImage(&image);
 }
 
-void HandleLZCompressCommand(char *inputPath, char *outputPath, int argc UNUSED, char **argv UNUSED)
+void HandleLZCompressCommand(char *inputPath, char *outputPath, int argc, char **argv)
 {
+	int overflowSize = 0;
+
+	for (int i = 3; i < argc; i++) {
+		char *option = argv[i];
+
+		if (strcmp(option, "-overflow") == 0) {
+			if (i + 1 >= argc)
+				FATAL_ERROR("No size following \"-overflow\".\n");
+
+			i++;
+
+			if (!ParseNumber(argv[i], NULL, 10, &overflowSize))
+				FATAL_ERROR("Failed to parse overflow size.\n");
+
+			if (overflowSize < 1)
+				FATAL_ERROR("Overflow size must be positive.\n");
+		} else {
+			FATAL_ERROR("Unrecognized option \"%s\".\n", option);
+		}
+	}
+
+	// The overflow option allows a quirk in some of Ruby/Sapphire's tilesets
+	// to be reproduced. It works by appending a number of zeros to the data
+	// before compressing it and then amending the LZ header's size field to
+	// reflect the expected size. This will cause an overflow when decompressing
+	// the data.
+
 	int fileSize;
-	unsigned char *buffer = ReadWholeFile(inputPath, &fileSize);
+	unsigned char *buffer = ReadWholeFileZeroPadded(inputPath, &fileSize, overflowSize);
 
 	int compressedSize;
-	unsigned char *compressedData = LZCompress(buffer, fileSize, &compressedSize);
+	unsigned char *compressedData = LZCompress(buffer, fileSize + overflowSize, &compressedSize);
+
+	compressedData[1] = (unsigned char)fileSize;
+	compressedData[2] = (unsigned char)(fileSize >> 8);
+	compressedData[3] = (unsigned char)(fileSize >> 16);
 
 	free(buffer);
 
@@ -297,7 +328,7 @@ int main(int argc, char **argv)
 
 	for (int i = 0; handlers[i].function != NULL; i++) {
 		if ((handlers[i].inputFileExtension == NULL || strcmp(handlers[i].inputFileExtension, inputFileExtension) == 0)
-			&& (handlers[i].outputFileExtension == NULL || strcmp(handlers[i].outputFileExtension, outputFileExtension) == 0)) {
+		 && (handlers[i].outputFileExtension == NULL || strcmp(handlers[i].outputFileExtension, outputFileExtension) == 0)) {
 			handlers[i].function(inputPath, outputPath, argc, argv);
 			return 0;
 		}
diff --git a/tools/gbagfx/util.c b/tools/gbagfx/util.c
index 5af380184..87abeb31c 100644
--- a/tools/gbagfx/util.c
+++ b/tools/gbagfx/util.c
@@ -84,6 +84,32 @@ unsigned char *ReadWholeFile(char *path, int *size)
 	return buffer;
 }
 
+unsigned char *ReadWholeFileZeroPadded(char *path, int *size, int padAmount)
+{
+	FILE *fp = fopen(path, "rb");
+
+	if (fp == NULL)
+		FATAL_ERROR("Failed to open \"%s\" for reading.\n", path);
+
+	fseek(fp, 0, SEEK_END);
+
+	*size = ftell(fp);
+
+	unsigned char *buffer = calloc(*size + padAmount, 1);
+
+	if (buffer == NULL)
+		FATAL_ERROR("Failed to allocate memory for reading \"%s\".\n", path);
+
+	rewind(fp);
+
+	if (fread(buffer, *size, 1, fp) != 1)
+		FATAL_ERROR("Failed to read \"%s\".\n", path);
+
+	fclose(fp);
+
+	return buffer;
+}
+
 void WriteWholeFile(char *path, void *buffer, int bufferSize)
 {
 	FILE *fp = fopen(path, "wb");
diff --git a/tools/gbagfx/util.h b/tools/gbagfx/util.h
index cb26a31ef..6d7a9c21e 100644
--- a/tools/gbagfx/util.h
+++ b/tools/gbagfx/util.h
@@ -8,6 +8,7 @@
 bool ParseNumber(char *s, char **end, int radix, int *intValue);
 char *GetFileExtension(char *path);
 unsigned char *ReadWholeFile(char *path, int *size);
+unsigned char *ReadWholeFileZeroPadded(char *path, int *size, int padAmount);
 void WriteWholeFile(char *path, void *buffer, int bufferSize);
 
 #endif // UTIL_H