Fix OOM for too-small overlay files in 32K mode (rgblink -t)

src/link/output.cpp

@@ -126,7 +126,8 @@ static uint32_t checkOverlaySize() {
 		warnx("Overlay file does not have a size multiple of 0x4000");
 	} else if (options.is32kMode && overlaySize != 0x8000) {
 		warnx("Overlay is not exactly 0x8000 bytes large");
-	} else if (overlaySize < 0x8000) {
+	}
+	if (overlaySize < 0x8000) {
 		warnx("Overlay is less than 0x8000 bytes large");
 	}
 
@@ -140,9 +141,11 @@ static void coverOverlayBanks(uint32_t nbOverlayBanks) {
 	// 2 if options.is32kMode, 1 otherwise
 	uint32_t nbRom0Banks = sectionTypeInfo[SECTTYPE_ROM0].size / BANK_SIZE;
 	// Discount ROM0 banks to avoid outputting too much
-	uint32_t nbUncoveredBanks = nbOverlayBanks - nbRom0Banks > sections[SECTTYPE_ROMX].size()
-	                                ? nbOverlayBanks - nbRom0Banks
-	                                : 0;
+	uint32_t nbUncoveredBanks =
+	    nbOverlayBanks >= nbRom0Banks
+	            && nbOverlayBanks - nbRom0Banks > sections[SECTTYPE_ROMX].size()
+	        ? nbOverlayBanks - nbRom0Banks
+	        : 0;
 
 	if (nbUncoveredBanks > sections[SECTTYPE_ROMX].size()) {
 		for (uint32_t i = sections[SECTTYPE_ROMX].size(); i < nbUncoveredBanks; ++i) {

test/link/overlay/smaller-32k/a.asm

@@ -0,0 +1,2 @@
+SECTION "test", ROM0[$42]
+Label:: dw Label

test/link/overlay/smaller-32k/out.err

@@ -0,0 +1,3 @@
+warning: Overlay file does not have a size multiple of 0x4000
+warning: Overlay is less than 0x8000 bytes large
+warning: Output is larger than overlay file, but no padding value was specified

test/link/overlay/smaller/out.err

@@ -1 +1,2 @@
 warning: Overlay file does not have a size multiple of 0x4000
+warning: Overlay is less than 0x8000 bytes large

test/link/test.sh

@@ -260,6 +260,16 @@ tryDiff "$test"/out.err "$outtemp"
 tryCmp "$test"/out.gb "$gbtemp"
 evaluateTest
 
+test="overlay/smaller-32k"
+startTest
+"$RGBASM" -o "$otemp" "$test"/a.asm
+continueTest
+rgblinkQuiet -o "$gbtemp" -t -O "$test"/overlay.gb "$otemp" 2>"$outtemp"
+tryDiff "$test"/out.err "$outtemp"
+# This test does not trim its output with 'dd' because it needs to verify the correct output size
+tryCmp "$test"/out.gb "$gbtemp"
+evaluateTest
+
 test="overlay/unfixed"
 startTest
 "$RGBASM" -o "$otemp" "$test"/a.asm