From 8947db2037f366eb55650b6d2bf8c5ce5ee037b2 Mon Sep 17 00:00:00 2001
From: d0k3 <tore.anon@gmail.com>
Date: Fri, 9 Dec 2016 15:40:13 +0100
Subject: [PATCH] Fix detection of trimmed NCSD images

---
 source/filetype.c  |  2 +-
 source/game/ncsd.c | 12 ++++++++++++
 source/game/ncsd.h |  1 +
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/source/filetype.c b/source/filetype.c
index c9153fb..c224ac0 100644
--- a/source/filetype.c
+++ b/source/filetype.c
@@ -40,7 +40,7 @@ u32 IdentifyFileType(const char* path) {
             return GAME_CIA; // CIA file
     } else if (ValidateNcsdHeader((NcsdHeader*) (void*) header) == 0) {
         NcsdHeader* ncsd = (NcsdHeader*) (void*) header;
-        if (fsize >= (ncsd->size * NCSD_MEDIA_UNIT))
+        if (fsize >= GetNcsdTrimmedSize(ncsd))
             return GAME_NCSD; // NCSD (".3DS") file
     } else if (ValidateNcchHeader((NcchHeader*) (void*) header) == 0) {
         NcchHeader* ncch = (NcchHeader*) (void*) header;
diff --git a/source/game/ncsd.c b/source/game/ncsd.c
index ad7797f..bedadd2 100644
--- a/source/game/ncsd.c
+++ b/source/game/ncsd.c
@@ -20,3 +20,15 @@ u32 ValidateNcsdHeader(NcsdHeader* header) {
      
     return 0;
 }
+
+u32 GetNcsdTrimmedSize(NcsdHeader* header) {
+    u32 data_units = 0;
+    for (u32 i = 0; i < 8; i++) {
+        NcchPartition* partition = header->partitions + i;
+        u32 partition_end = partition->offset + partition->size;
+        if (!partition->size) continue;
+        data_units = (partition_end > data_units) ? partition_end : data_units;
+    }
+    
+    return data_units * NCSD_MEDIA_UNIT;
+}
diff --git a/source/game/ncsd.h b/source/game/ncsd.h
index 14ab3ea..2a08a46 100644
--- a/source/game/ncsd.h
+++ b/source/game/ncsd.h
@@ -32,3 +32,4 @@ typedef struct {
 } __attribute__((packed)) NcsdHeader;
 
 u32 ValidateNcsdHeader(NcsdHeader* header);
+u32 GetNcsdTrimmedSize(NcsdHeader* header);