From 9e00e5394e6965e01624df1aa92c5c2855d68928 Mon Sep 17 00:00:00 2001
From: urmum-69 <urmum69@snopyta.org>
Date: Sat, 20 Mar 2021 18:54:21 +0000
Subject: [PATCH] Implement calculating SHA1 hash of files (#86)

* implement calculating SHA1 hash of a file

* fix bug where incorrect SHA1 hash would be calculated
---
 arm9/source/fileOperations.cpp | 34 ++++++++++++++++++++++++++++++++++
 arm9/source/fileOperations.h   |  1 +
 arm9/source/file_browse.cpp    | 31 +++++++++++++++++++++++++++++--
 arm9/source/file_browse.h      |  1 +
 4 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/arm9/source/fileOperations.cpp b/arm9/source/fileOperations.cpp
index 14e1d81..5c1b33e 100644
--- a/arm9/source/fileOperations.cpp
+++ b/arm9/source/fileOperations.cpp
@@ -9,6 +9,7 @@
 #include "file_browse.h"
 
 #define copyBufSize 0x8000
+#define shaChunkSize 0x10000
 
 u32 copyBuf[copyBufSize];
 
@@ -68,6 +69,39 @@ off_t getFileSize(const char *fileName)
 	return fsize;
 }
 
+bool calculateSHA1(const char *fileName, u8 *sha1)
+{
+	off_t fsize = getFileSize(fileName);
+	u8 *buf = (u8*) malloc(shaChunkSize);
+	if (!buf) {
+		iprintf("Could not allocate buffer\n");
+		return false;
+	}
+	FILE* fp = fopen(fileName, "rb");
+	if (!fp) {
+		iprintf("Could not open file for reading\n");
+		free(buf);
+		return false;
+	}
+	memset(sha1, 0, 20);
+	swiSHA1context_t ctx;
+	ctx.sha_block=0; //this is weird but it has to be done
+	swiSHA1Init(&ctx);
+	while (true) {
+		size_t ret = fread(buf, 1, shaChunkSize, fp);
+		if (!ret) break;
+		swiSHA1Update(&ctx, buf, ret);
+		scanKeys();
+		int keys = keysHeld();
+		if (keys & KEY_START) return false;
+		iprintf("\x1b[1;A");
+		iprintf("%ld/%lld bytes\n", ftell(fp), fsize);
+	}
+	swiSHA1Final(sha1, &ctx);
+	free(buf);
+	return true;
+}
+
 void dirCopy(DirEntry* entry, int i, const char *destinationPath, const char *sourcePath) {
 	std::vector<DirEntry> dirContents;
 	dirContents.clear();
diff --git a/arm9/source/fileOperations.h b/arm9/source/fileOperations.h
index 795ebed..a7e0931 100644
--- a/arm9/source/fileOperations.h
+++ b/arm9/source/fileOperations.h
@@ -23,6 +23,7 @@ extern void printBytes(int bytes);
 extern void printBytesAlign(int bytes);
 
 extern off_t getFileSize(const char *fileName);
+extern bool calculateSHA1(const char *fileName, u8 *sha1);
 extern int fcopy(const char *sourcePath, const char *destinationPath);
 void changeFileAttribs(DirEntry* entry);
 
diff --git a/arm9/source/file_browse.cpp b/arm9/source/file_browse.cpp
index 052fa6a..fc73e01 100644
--- a/arm9/source/file_browse.cpp
+++ b/arm9/source/file_browse.cpp
@@ -242,8 +242,12 @@ FileOperation fileBrowse_A(DirEntry* entry, char path[PATH_MAX]) {
 		assignedOp[++maxCursors] = FileOperation::copyFatOut;
 		printf("   Copy to fat:/gm9i/out\n");
 	}
-	printf("\n");
-	printf("(<A> select, <B> cancel)");
+	// The bios SHA1 functions are only availible on the DSi
+	// https://problemkaputt.de/gbatek.htm#biossha1functionsdsionly
+	if (isDSiMode()) {
+		assignedOp[++maxCursors] = FileOperation::calculateSHA1;
+		printf("   Calculate SHA1 hash\n");
+	}
 	consoleSelect(&bottomConsole);
 	printf ("\x1B[47m");		// Print foreground white color
 	while (true) {
@@ -375,6 +379,29 @@ FileOperation fileBrowse_A(DirEntry* entry, char path[PATH_MAX]) {
 						currentDrive = 6;
 					}
 					break;
+				} case FileOperation::calculateSHA1: {
+					iprintf("\x1b[2J");
+					iprintf("Calculating SHA1 hash of:\n%s\n", entry->name.c_str());
+					iprintf("Press <START> to cancel\n\n");
+					u8 sha1[20] = {0};
+					bool ret = calculateSHA1(strcat(getcwd(path, PATH_MAX), entry->name.c_str()), sha1);
+					if (!ret) break;
+					iprintf("SHA1 hash is: ");
+					for (int i = 0; i < 19; ++i) iprintf("%02X", sha1[i]);
+					consoleSelect(&topConsole);
+					iprintf ("\x1B[30m");           // Print black color
+					// Power saving loop. Only poll the keys once per frame and sleep the CPU if there is nothing else to do
+					int pressed;
+					do {
+						// Move to right side of screen
+						iprintf ("\x1b[0;26H");
+						// Print time
+						iprintf (" %s" ,RetTime().c_str());
+						scanKeys();
+						pressed = keysDownRepeat();
+						swiWaitForVBlank();
+					} while (!(pressed & (KEY_A | KEY_Y | KEY_B | KEY_X)));
+					break;
 				} case FileOperation::none: {
 					break;
 				}
diff --git a/arm9/source/file_browse.h b/arm9/source/file_browse.h
index 0255590..367543e 100644
--- a/arm9/source/file_browse.h
+++ b/arm9/source/file_browse.h
@@ -43,6 +43,7 @@ enum class FileOperation {
 	showInfo,
 	copySdOut,
 	copyFatOut,
+	calculateSHA1,
 };
 
 bool extension(const std::string &filename, const std::vector<std::string> &extensions);