From a41bca3183351e84adc1694ba7643fe2656977c8 Mon Sep 17 00:00:00 2001
From: Pete Batard <pete@akeo.ie>
Date: Tue, 24 May 2016 11:48:10 +0100
Subject: [PATCH] [checksum] fix wrong checksums for content that isn't a
 multiple of 64 bytes

* Leading odd-sized chunks needs to be tested *before* updating the bytecount
* Closes #761
---
 src/checksum.c | 56 ++++++++++++++++++++++----------------------------
 src/rufus.rc   | 10 ++++-----
 2 files changed, 30 insertions(+), 36 deletions(-)

diff --git a/src/checksum.c b/src/checksum.c
index 397c59c4..c9db99cb 100644
--- a/src/checksum.c
+++ b/src/checksum.c
@@ -453,26 +453,24 @@ static void md5_transform(SUM_CONTEXT *ctx, const unsigned char *data)
 /* Update the message digest with the contents of the buffer (SHA-1) */
 static void sha1_write(SUM_CONTEXT *ctx, const unsigned char *buf, size_t len)
 {
-	size_t t;
+	size_t num = ctx->bytecount & 0x3f;
 
 	/* Update bytecount */
 	ctx->bytecount += len;
 
-	t = ctx->bytecount & 0x3f;
-
 	/* Handle any leading odd-sized chunks */
-	if (t) {
-		unsigned char *p = ctx->buf + t;
+	if (num) {
+		unsigned char *p = ctx->buf + num;
 
-		t = 64 - t;
-		if (len < t) {
+		num = 64 - num;
+		if (len < num) {
 			memcpy(p, buf, len);
 			return;
 		}
-		memcpy(p, buf, t);
+		memcpy(p, buf, num);
 		sha1_transform(ctx, ctx->buf);
-		buf += t;
-		len -= t;
+		buf += num;
+		len -= num;
 	}
 
 	/* Process data in 64-byte chunks */
@@ -490,26 +488,24 @@ static void sha1_write(SUM_CONTEXT *ctx, const unsigned char *buf, size_t len)
 /* Update the message digest with the contents of the buffer (SHA-256) */
 static void sha256_write(SUM_CONTEXT *ctx, const unsigned char *buf, size_t len)
 {
-	size_t t;
+	size_t num = ctx->bytecount & 0x3f;
 
 	/* Update bytecount */
 	ctx->bytecount += len;
 
-	t = ctx->bytecount & 0x3f;
-
 	/* Handle any leading odd-sized chunks */
-	if (t) {
-		unsigned char *p = ctx->buf + t;
+	if (num) {
+		unsigned char *p = ctx->buf + num;
 
-		t = 64 - t;
-		if (len < t) {
+		num = 64 - num;
+		if (len < num) {
 			memcpy(p, buf, len);
 			return;
 		}
-		memcpy(p, buf, t);
+		memcpy(p, buf, num);
 		sha256_transform(ctx, ctx->buf);
-		buf += t;
-		len -= t;
+		buf += num;
+		len -= num;
 	}
 
 	/* Process data in 64-byte chunks */
@@ -527,26 +523,24 @@ static void sha256_write(SUM_CONTEXT *ctx, const unsigned char *buf, size_t len)
 /* Update the message digest with the contents of the buffer (MD5) */
 static void md5_write(SUM_CONTEXT *ctx, const unsigned char *buf, size_t len)
 {
-	size_t t;
+	size_t num = ctx->bytecount & 0x3f;
 
 	/* Update bytecount */
 	ctx->bytecount += len;
 
-	t = ctx->bytecount & 0x3f;
-
 	/* Handle any leading odd-sized chunks */
-	if (t) {
-		unsigned char *p = ctx->buf + t;
+	if (num) {
+		unsigned char *p = ctx->buf + num;
 
-		t = 64 - t;
-		if (len < t) {
-			memcpy(p, buf, len);
+		num = 64 - num;
+		if (len < num) {
+			memcpy(p, buf, num);
 			return;
 		}
-		memcpy(p, buf, t);
+		memcpy(p, buf, num);
 		md5_transform(ctx, ctx->buf);
-		buf += t;
-		len -= t;
+		buf += num;
+		len -= num;
 	}
 
 	/* Process data in 64-byte chunks */
diff --git a/src/rufus.rc b/src/rufus.rc
index 172068a4..06151ebe 100644
--- a/src/rufus.rc
+++ b/src/rufus.rc
@@ -33,7 +33,7 @@ LANGUAGE LANG_NEUTRAL, SUBLANG_NEUTRAL
 IDD_DIALOG DIALOGEX 12, 12, 242, 376
 STYLE DS_SETFONT | DS_MODALFRAME | DS_CENTER | WS_MINIMIZEBOX | WS_POPUP | WS_CAPTION | WS_SYSMENU
 EXSTYLE WS_EX_ACCEPTFILES
-CAPTION "Rufus 2.10.937"
+CAPTION "Rufus 2.10.938"
 FONT 8, "Segoe UI Symbol", 400, 0, 0x0
 BEGIN
     LTEXT           "Device",IDS_DEVICE_TXT,9,6,200,8
@@ -320,8 +320,8 @@ END
 //
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 2,10,937,0
- PRODUCTVERSION 2,10,937,0
+ FILEVERSION 2,10,938,0
+ PRODUCTVERSION 2,10,938,0
  FILEFLAGSMASK 0x3fL
 #ifdef _DEBUG
  FILEFLAGS 0x1L
@@ -338,13 +338,13 @@ BEGIN
         BEGIN
             VALUE "CompanyName", "Akeo Consulting (http://akeo.ie)"
             VALUE "FileDescription", "Rufus"
-            VALUE "FileVersion", "2.10.937"
+            VALUE "FileVersion", "2.10.938"
             VALUE "InternalName", "Rufus"
             VALUE "LegalCopyright", "© 2011-2016 Pete Batard (GPL v3)"
             VALUE "LegalTrademarks", "http://www.gnu.org/copyleft/gpl.html"
             VALUE "OriginalFilename", "rufus.exe"
             VALUE "ProductName", "Rufus"
-            VALUE "ProductVersion", "2.10.937"
+            VALUE "ProductVersion", "2.10.938"
         END
     END
     BLOCK "VarFileInfo"