Fix zero-length Sha256 hash

diff --git a/libctru/source/services/fs.c b/libctru/source/services/fs.c
index 35f36068ca81a4e34937af4eb9cc8e8f0920dad6..db1a75f39f94a83879cc6bdd2f2976613f8b50e4 100644 (file)
--- a/libctru/source/services/fs.c
+++ b/libctru/source/services/fs.c
@@ -1203,6 +1203,30 @@ Result FSUSER_GetLegacySubBannerData(u32 bannerSize, FS_MediaType mediaType, u64
 
 Result FSUSER_UpdateSha256Context(const void* data, u32 inputSize, u8* hash)
 {
+       if(!inputSize)
+       {
+               // For some reason a zero-size input outputs a garbage hash,
+               // so bypass the service call and just output it here.
+               if(hash)
+               {
+                       static const u8 sha256_empty[32] =
+                       {
+                               0xE3, 0xB0, 0xC4, 0x42,
+                               0x98, 0xFC, 0x1C, 0x14,
+                               0x9A, 0xFB, 0xF4, 0xC8,
+                               0x99, 0x6F, 0xB9, 0x24,
+                               0x27, 0xAE, 0x41, 0xE4,
+                               0x64, 0x9B, 0x93, 0x4C,
+                               0xA4, 0x95, 0x99, 0x1B,
+                               0x78, 0x52, 0xB8, 0x55,
+                       };
+
+                       memcpy(hash, sha256_empty, 0x20);
+               }
+
+               return 0;
+       }
+
        u32 *cmdbuf = getThreadCommandBuffer();
 
        cmdbuf[0] = IPC_MakeHeader(0x84E, 13, 2); // 0x84E0342