From 439a7a1828d377994f69cbc4b625a401856e915f Mon Sep 17 00:00:00 2001
From: Rangi <sylvie.oukaour+rangi42@gmail.com>
Date: Sat, 12 Sep 2026 11:50:47 -0400
Subject: [PATCH] Fix reversing multiple palettes with fewer than 4 colors per
 palette

Fixes #2073
---
 src/gfx/reverse.cpp                    |  13 +++++++------
 test/gfx/reverse_multi_palette.2bpp    | Bin 0 -> 32 bytes
 test/gfx/reverse_multi_palette.attrmap | Bin 0 -> 3 bytes
 test/gfx/reverse_multi_palette.flags   |   5 +++++
 test/gfx/reverse_multi_palette.pal     | Bin 0 -> 8 bytes
 test/gfx/reverse_multi_palette.tilemap | Bin 0 -> 3 bytes
 6 files changed, 12 insertions(+), 6 deletions(-)
 create mode 100644 test/gfx/reverse_multi_palette.2bpp
 create mode 100644 test/gfx/reverse_multi_palette.attrmap
 create mode 100644 test/gfx/reverse_multi_palette.flags
 create mode 100644 test/gfx/reverse_multi_palette.pal
 create mode 100644 test/gfx/reverse_multi_palette.tilemap

diff --git a/src/gfx/reverse.cpp b/src/gfx/reverse.cpp
index f0e3e7d6..9d6a6c35 100644
--- a/src/gfx/reverse.cpp
+++ b/src/gfx/reverse.cpp
@@ -217,16 +217,17 @@ void reverse() {
 
 		palettes.clear();
 		std::array<uint8_t, sizeof(uint16_t) * 4> buf; // max 4 colors
-		assume(buf.size() >= sizeof(uint16_t) * options.nbColorsPerPal);
+		size_t const palSize = sizeof(uint16_t) * options.nbColorsPerPal;
+		assume(buf.size() >= palSize);
 		for (;;) {
-			if (size_t nbRead = file->sgetn(reinterpret_cast<char *>(buf.data()), buf.size());
+			if (size_t nbRead = file->sgetn(reinterpret_cast<char *>(buf.data()), palSize);
 			    nbRead == 0) {
 				break;
-			} else if (nbRead != sizeof(uint16_t) * options.nbColorsPerPal) {
+			} else if (nbRead != palSize) {
 				fatal(
-				    "Palette data size (%zu) is not a multiple of %zu bytes\n",
-				    palettes.size() * buf.size() + nbRead,
-				    buf.size()
+				    "Palette data size (%zu) is not a multiple of %zu bytes",
+				    palettes.size() * palSize + nbRead,
+				    palSize
 				);
 			}
 			// Expand the colors
diff --git a/test/gfx/reverse_multi_palette.2bpp b/test/gfx/reverse_multi_palette.2bpp
new file mode 100644
index 0000000000000000000000000000000000000000..c4b4f6c428512c5e3b3d96289bff51fd07206a0b
GIT binary patch
literal 32
OcmZQzKn4F9P$2+E*a!Il

literal 0
HcmV?d00001

diff --git a/test/gfx/reverse_multi_palette.attrmap b/test/gfx/reverse_multi_palette.attrmap
new file mode 100644
index 0000000000000000000000000000000000000000..180cf4bf96a427be11dc33679b684a52de644751
GIT binary patch
literal 3
KcmZQzWB>pF1pop7

literal 0
HcmV?d00001

diff --git a/test/gfx/reverse_multi_palette.flags b/test/gfx/reverse_multi_palette.flags
new file mode 100644
index 00000000..fb08b10f
--- /dev/null
+++ b/test/gfx/reverse_multi_palette.flags
@@ -0,0 +1,5 @@
+-s 2
+-u
+-t reverse_multi_palette.tilemap
+-a reverse_multi_palette.attrmap
+-p reverse_multi_palette.pal
diff --git a/test/gfx/reverse_multi_palette.pal b/test/gfx/reverse_multi_palette.pal
new file mode 100644
index 0000000000000000000000000000000000000000..ce75044dfd85549aed7c3c6157e3dcb330939177
GIT binary patch
literal 8
Pcmb1VV5oV({Qo}y3GxGd

literal 0
HcmV?d00001

diff --git a/test/gfx/reverse_multi_palette.tilemap b/test/gfx/reverse_multi_palette.tilemap
new file mode 100644
index 0000000000000000000000000000000000000000..fa37ca9bf9d6b25c9ce0d8fd77695970b595e6fb
GIT binary patch
literal 3
KcmZQzU<3dF1ONg6

literal 0
HcmV?d00001