Only dump the RSA key on trimmed ROMs when it exists (#215)

* Only dump the RSA key on trimmed ROMs when it exists * Check for 'ac' magic number instead of 0xFF Thanks @bWFpbA
DS-Homebrew · Dec 31, 2023 · d588ac0 · d588ac0
1 parent 088fd0d
commit d588ac0
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Showing 2 changed files with 33 additions and 5 deletions.
diff --git a/arm9/source/dumpOperations.cpp b/arm9/source/dumpOperations.cpp
@@ -867,7 +867,7 @@ void ndsCardDump(void) {
 		u32 romSize;
 		if (dumpOption & DumpOption::romTrimmed) {
 			romSize = (isDSiMode() && (ndsCardHeader.unitCode != 0) && (ndsCardHeader.twlRomSize > 0))
-						? ndsCardHeader.twlRomSize : ndsCardHeader.romSize+0x88;
+						? ndsCardHeader.twlRomSize : ndsCardHeader.romSize + 0x88;
 		} else {
 			romSize = 0x20000 << ndsCardHeader.deviceSize;
 		}
@@ -892,10 +892,23 @@ void ndsCardDump(void) {
 				for (u32 i = 0; i < 0x8000; i += 0x200) {
 					cardRead (src+i, copyBuf+i, false);
 				}
-				if (fwrite(copyBuf, 1, (currentSize>=0x8000 ? 0x8000 : currentSize), destinationFile) < 1) {
+
+				if (currentSize < 0x8000) {
+					if (romSize == ndsCardHeader.romSize + 0x88) {
+						// Trimming, check for RSA key
+						// 'ac', auth code -- magic number
+						if (*(u16 *)(copyBuf + (ndsCardHeader.romSize % 0x8000)) != 0x6361) {
+							romSize -= 0x88;
+							currentSize -= 0x88;
+						}
+					}
+
+					fwrite(copyBuf, 1, currentSize, destinationFile);
+				} else if (fwrite(copyBuf, 1, 0x8000, destinationFile) < 1) {
 					dumpFailMsg(STR_FAILED_TO_DUMP_ROM);
 					break;
 				}
+
 				currentSize -= 0x8000;
 			}
 			fclose(destinationFile);

diff --git a/arm9/source/fileOperations.cpp b/arm9/source/fileOperations.cpp
@@ -136,11 +136,26 @@ int trimNds(const char *fileName) {
 
 		fseek(file, 0, SEEK_END);
 		u32 fileSize = ftell(file);
+		fseek(file, 0, SEEK_SET);
 
-		fclose(file);
+		u32 romSize;
+		if((ndsCardHeader.unitCode != 0) && (ndsCardHeader.twlRomSize > 0)) {
+			romSize = ndsCardHeader.twlRomSize;
+		} else {
+			romSize = ndsCardHeader.romSize;
+
+			// Check if it has an RSA key or not
+			fseek(file, romSize, SEEK_SET);
+			u16 magic;
+			if(fread(&magic, sizeof(u16), 1, file) == 1) {
+				// 'ac', auth code -- magic number
+				if(magic == 0x6361)
+					romSize += 0x88;
+			}
 
-		u32 romSize = ((ndsCardHeader.unitCode != 0) && (ndsCardHeader.twlRomSize > 0))
-						? ndsCardHeader.twlRomSize : ndsCardHeader.romSize + 0x88;
+		}
+
+		fclose(file);
 
 		if(fileSize == romSize) {
 			font->clear(false);