libtiff 4.7 now returns -1 for some warnings

jcupitt · jcupitt · commit 140d14f482be · 2024-12-13T15:28:00.000Z
Don't bail out if TIFFReadScanline() and TIFFReadEncodedStrip() return -1. libtiff 4.7.0 and maybe earlier have started returning error values for truncated strips. Maybe other API points now return error codes for warnings too? see #4317
diff --git a/ChangeLog b/ChangeLog
@@ -10,6 +10,7 @@
 - heifsave: prevent use of AV1 intra block copy feature [lovell]
 - threadpool: improve cooperative downsizing [kleisauke]
 - fix alpha shift during colourspace conversions [frederikrosenberg]
+- improve error handling with libtiff 4.7 [CrispinStichartFNSB]
 
 10/10/24 8.16.0
 
diff --git a/libvips/foreign/tiff2vips.c b/libvips/foreign/tiff2vips.c
@@ -686,11 +686,10 @@ rtiff_strip_read(Rtiff *rtiff, int strip, tdata_t buf)
 		length = TIFFReadEncodedStrip(rtiff->tiff,
 			strip, buf, (tsize_t) -1);
 
-	if (length == -1) {
-		vips_foreign_load_invalidate(rtiff->out);
-		vips_error("tiff2vips", "%s", _("read error"));
-		return -1;
-	}
+	/* We get a length == -1 return for warnings with libtiff 4.7.0, we need
+	 * to ignore it.
+	 */
+	(void) length;
 
 	return 0;
 }
