From c8ead48e3384bd6c9f80eb1dc78c77ae680a7d3b Mon Sep 17 00:00:00 2001
From: Rupert <bmplibinfo@gmail.com>
Date: Sat, 21 Jun 2025 11:01:53 +0200
Subject: [PATCH] add icon/pointer settings-sanity check

---
 bmp-read-loadimage.c | 33 ++++++++++++++++++++++++++++++---
 bmp-read.c           |  5 ++++-
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/bmp-read-loadimage.c b/bmp-read-loadimage.c
index f32acdd..15d28d3 100644
--- a/bmp-read-loadimage.c
+++ b/bmp-read-loadimage.c
@@ -74,6 +74,7 @@ static void s_read_indexed_line(BMPREAD_R rp, unsigned char *restrict line);
 static void s_read_rle_line(BMPREAD_R rp, unsigned char *restrict line,
                                int *restrict x, int *restrict yoff);
 static void s_read_huffman_line(BMPREAD_R rp, unsigned char *restrict line);
+static bool s_are_settings_icon_compatible(BMPREAD_R rp);
 
 static_assert(sizeof(float) == 4, "sizeof(float) must be 4. Cannot build bmplib.");
 static_assert(sizeof(int) * CHAR_BIT >= 32, "int must be at least 32bit. Cannot build bmplib.");
@@ -156,6 +157,15 @@ static BMPRESULT s_load_image_or_line(BMPREAD_R rp, unsigned char **restrict buf
 		return BMP_RESULT_INSANE;
 	}
 
+	if (rp->read_state < RS_LOAD_STARTED && rp->is_icon) {
+		if (!s_are_settings_icon_compatible(rp)) {
+			logerr(rp->c.log, "Panic! Trying to load icon/pointer with incompatibele settings.\n");
+			rp->read_state = RS_FATAL;
+			rp->lasterr = BMP_ERR_INTERNAL;
+			return BMP_RESULT_ERROR;
+		}
+	}
+
 	if (!buffer) {
 		logerr(rp->c.log, "Buffer pointer is NULL. (It may point to a NULL pointer, but must not itself be NULL)");
 		return BMP_RESULT_ERROR;
@@ -217,7 +227,27 @@ abort:
 	return BMP_RESULT_ERROR;
 }
 
+static bool s_are_settings_icon_compatible(BMPREAD_R rp)
+{
+	/* some catch-all sanity checks for icons/pointers. Strictly, these
+	 * shouldn't be necessary, as they should have been caught already.
+	 * If any of these fail, there is a bug somewhere else.
+	 */
 
+	if (rp->result_channels != 4 || rp->result_bitsperchannel != 8)
+		return false;
+
+	if (rp->result_format != BMP_FORMAT_INT)
+		return false;
+
+	if (rp->rle && (rp->undefined_mode != BMP_UNDEFINED_LEAVE))
+		return false;
+
+	if (!(rp->rle || (rp->ih->compression == BI_RGB)))
+		return false;
+
+	return true;
+}
 
 /********************************************************
  * 	apply_icon_alpha
@@ -225,9 +255,6 @@ abort:
 
 static void apply_icon_alpha(BMPREAD_R rp, int y, unsigned char *restrict line)
 {
-	if (!(rp->result_channels == 4 && rp->result_bitsperchannel == 8))
-		return;
-
 	for (int x = 0; x < rp->width; x++) {
 		line[x * 4 + 3] = rp->icon_mono_and[(rp->height - y - 1) * rp->width + x];
 	}
diff --git a/bmp-read.c b/bmp-read.c
index faa6f11..c6ed1e8 100644
--- a/bmp-read.c
+++ b/bmp-read.c
@@ -815,7 +815,10 @@ static bool s_is_bmptype_supported(BMPREAD_R rp)
 	}
 
 	if (rp->is_icon) {
-		if (rp->ih->compression != BI_RGB) {
+		if (rp->ih->compression != BI_RGB &&
+		    rp->ih->compression != BI_RLE4 &&
+		    rp->ih->compression != BI_RLE8 &&
+		    rp->ih->compression != BI_OS2_RLE24) {
 			logerr(rp->c.log, "Unsupported compression %s for icon/pointer",
 			                                         s_compression_name(rp->ih->compression));
 			rp->lasterr = BMP_ERR_UNSUPPORTED;