From 8db3d6b700b1a8097a16ff27356d3dfed9c0f1e8 Mon Sep 17 00:00:00 2001
From: tobi <tobi.smethurst@protonmail.com>
Date: Mon, 2 Sep 2024 15:08:07 +0200
Subject: [PATCH] allow overflow in imaging

---
 internal/media/imaging.go | 108 ++++++--------------------------------
 1 file changed, 16 insertions(+), 92 deletions(-)

diff --git a/internal/media/imaging.go b/internal/media/imaging.go
index e724e22b8..23fd2f838 100644
--- a/internal/media/imaging.go
+++ b/internal/media/imaging.go
@@ -399,25 +399,9 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 					g16 := uint16(s[1])
 					b16 := uint16(s[2])
 					a16 := uint16(a)
-
-					d0 := r16 * 0xff / a16
-					if d0 > math.MaxUint8 {
-						panic("overflow d0")
-					}
-
-					d1 := g16 * 0xff / a16
-					if d1 > math.MaxUint8 {
-						panic("overflow d1")
-					}
-
-					d2 := b16 * 0xff / a16
-					if d2 > math.MaxUint8 {
-						panic("overflow d2")
-					}
-
-					d[0] = uint8(d0) // #nosec G115 -- Just checked.
-					d[1] = uint8(d1) // #nosec G115 -- Just checked.
-					d[2] = uint8(d2) // #nosec G115 -- Just checked.
+					d[0] = uint8(r16 * 0xff / a16) // #nosec G115 -- Overflow desired.
+					d[1] = uint8(g16 * 0xff / a16) // #nosec G115 -- Overflow desired.
+					d[2] = uint8(b16 * 0xff / a16) // #nosec G115 -- Overflow desired.
 					d[3] = a
 				}
 				j += 4
@@ -447,25 +431,9 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 					g32 := uint32(s[2])<<8 | uint32(s[3])
 					b32 := uint32(s[4])<<8 | uint32(s[5])
 					a32 := uint32(s[6])<<8 | uint32(s[7])
-
-					d0 := (r32 * 0xffff / a32) >> 8
-					if d0 > math.MaxUint8 {
-						panic("overflow d0")
-					}
-
-					d1 := (g32 * 0xffff / a32) >> 8
-					if d1 > math.MaxUint8 {
-						panic("overflow d1")
-					}
-
-					d2 := (b32 * 0xffff / a32) >> 8
-					if d2 > math.MaxUint8 {
-						panic("overflow d2")
-					}
-
-					d[0] = uint8(d0) // #nosec G115 -- Just checked.
-					d[1] = uint8(d1) // #nosec G115 -- Just checked.
-					d[2] = uint8(d2) // #nosec G115 -- Just checked.
+					d[0] = uint8((r32 * 0xffff / a32) >> 8) // #nosec G115 -- Overflow desired.
+					d[1] = uint8((g32 * 0xffff / a32) >> 8) // #nosec G115 -- Overflow desired.
+					d[2] = uint8((b32 * 0xffff / a32) >> 8) // #nosec G115 -- Overflow desired.
 				}
 				d[3] = a
 				j += 4
@@ -546,9 +514,6 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 				} else {
 					r = ^(r >> 31)
 				}
-				if r > math.MaxUint8 {
-					panic("overflow r")
-				}
 
 				g := yy1 - 22554*cb1 - 46802*cr1
 				if uint32(g)&0xff000000 == 0 {
@@ -556,9 +521,6 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 				} else {
 					g = ^(g >> 31)
 				}
-				if g > math.MaxUint8 {
-					panic("overflow g")
-				}
 
 				b := yy1 + 116130*cb1
 				if uint32(b)&0xff000000 == 0 {
@@ -566,14 +528,11 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 				} else {
 					b = ^(b >> 31)
 				}
-				if b > math.MaxUint8 {
-					panic("overflow b")
-				}
 
 				d := dst[j : j+4 : j+4]
-				d[0] = uint8(r) // #nosec G115 -- Just checked.
-				d[1] = uint8(g) // #nosec G115 -- Just checked.
-				d[2] = uint8(b) // #nosec G115 -- Just checked.
+				d[0] = uint8(r) // #nosec G115 -- Overflow desired.
+				d[1] = uint8(g) // #nosec G115 -- Overflow desired.
+				d[2] = uint8(b) // #nosec G115 -- Overflow desired.
 				d[3] = 0xff
 
 				iy++
@@ -610,24 +569,9 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 				d := dst[j : j+4 : j+4]
 				switch a16 {
 				case 0xffff:
-					d0 := r16 >> 8
-					if d0 > math.MaxUint8 {
-						panic("overflow d0")
-					}
-
-					d1 := g16 >> 8
-					if d1 > math.MaxUint8 {
-						panic("overflow d1")
-					}
-
-					d2 := b16 >> 8
-					if d2 > math.MaxUint8 {
-						panic("overflow d2")
-					}
-
-					d[0] = uint8(d0) // #nosec G115 -- Just checked.
-					d[1] = uint8(d1) // #nosec G115 -- Just checked.
-					d[2] = uint8(d2) // #nosec G115 -- Just checked.
+					d[0] = uint8(r16 >> 8) // #nosec G115 -- Overflow desired.
+					d[1] = uint8(g16 >> 8) // #nosec G115 -- Overflow desired.
+					d[2] = uint8(b16 >> 8) // #nosec G115 -- Overflow desired.
 					d[3] = 0xff
 				case 0:
 					d[0] = 0
@@ -635,30 +579,10 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 					d[2] = 0
 					d[3] = 0
 				default:
-					d0 := ((r16 * 0xffff) / a16) >> 8
-					if d0 > math.MaxUint8 {
-						panic("overflow d0")
-					}
-
-					d1 := ((g16 * 0xffff) / a16) >> 8
-					if d1 > math.MaxUint8 {
-						panic("overflow d1")
-					}
-
-					d2 := ((b16 * 0xffff) / a16) >> 8
-					if d2 > math.MaxUint8 {
-						panic("overflow d2")
-					}
-
-					d3 := a16 >> 8
-					if d3 > math.MaxUint8 {
-						panic("overflow d3")
-					}
-
-					d[0] = uint8(d0) // #nosec G115 -- Just checked.
-					d[1] = uint8(d1) // #nosec G115 -- Just checked.
-					d[2] = uint8(d2) // #nosec G115 -- Just checked.
-					d[3] = uint8(d3) // #nosec G115 -- Just checked.
+					d[0] = uint8(((r16 * 0xffff) / a16) >> 8) // #nosec G115 -- Overflow desired.
+					d[1] = uint8(((g16 * 0xffff) / a16) >> 8) // #nosec G115 -- Overflow desired.
+					d[2] = uint8(((b16 * 0xffff) / a16) >> 8) // #nosec G115 -- Overflow desired.
+					d[3] = uint8(a16 >> 8)                    // #nosec G115 -- Overflow desired.
 				}
 				j += 4
 			}