tiffcp doesn't have any code to copy subsampled images.  It can handle
JPEG-compressed input anyway by the expedient of telling the codec to
convert to RGB (and thereby upsample), but otherwise we have to punt to
avoid buffer overruns.  Per bug #588784, bug #460653, and upstream bug
http://bugzilla.maptools.org/show_bug.cgi?id=2097

This patch is a bit more than minimally sized because it rearranges
some of the existing code for simplicity.


diff -Naur tiff-3.8.2.orig/tools/tiffcp.c tiff-3.8.2/tools/tiffcp.c
--- tiff-3.8.2.orig/tools/tiffcp.c	2006-03-21 11:42:51.000000000 -0500
+++ tiff-3.8.2/tools/tiffcp.c	2010-06-13 16:08:21.000000000 -0400
@@ -540,6 +540,7 @@
 tiffcp(TIFF* in, TIFF* out)
 {
 	uint16 bitspersample, samplesperpixel;
+	uint16 input_compression, input_photometric;
 	copyFunc cf;
 	uint32 width, length;
 	struct cpTag* p;
@@ -552,26 +553,30 @@
 		TIFFSetField(out, TIFFTAG_COMPRESSION, compression);
 	else
 		CopyField(TIFFTAG_COMPRESSION, compression);
+	TIFFGetFieldDefaulted(in, TIFFTAG_COMPRESSION, &input_compression);
+	TIFFGetFieldDefaulted(in, TIFFTAG_PHOTOMETRIC, &input_photometric);
+	if (input_compression == COMPRESSION_JPEG) {
+		/* Force conversion to RGB */
+		TIFFSetField(in, TIFFTAG_JPEGCOLORMODE, JPEGCOLORMODE_RGB);
+	} else if (input_photometric == PHOTOMETRIC_YCBCR) {
+		/* Otherwise, can't handle subsampled input */
+		uint16 subsamplinghor,subsamplingver;
+
+		TIFFGetFieldDefaulted(in, TIFFTAG_YCBCRSUBSAMPLING,
+				      &subsamplinghor, &subsamplingver);
+		if (subsamplinghor!=1 || subsamplingver!=1) {
+			fprintf(stderr, "tiffcp: %s: Can't copy/convert subsampled image.\n",
+				TIFFFileName(in));
+			return FALSE;
+		}
+	}
 	if (compression == COMPRESSION_JPEG) {
-	    uint16 input_compression, input_photometric;
-
-            if (TIFFGetField(in, TIFFTAG_COMPRESSION, &input_compression)
-                 && input_compression == COMPRESSION_JPEG) {
-                TIFFSetField(in, TIFFTAG_JPEGCOLORMODE, JPEGCOLORMODE_RGB);
-            }
-	    if (TIFFGetField(in, TIFFTAG_PHOTOMETRIC, &input_photometric)) {
-		if(input_photometric == PHOTOMETRIC_RGB) {
-			if (jpegcolormode == JPEGCOLORMODE_RGB)
-		    		TIFFSetField(out, TIFFTAG_PHOTOMETRIC,
-					     PHOTOMETRIC_YCBCR);
-			else
-		    		TIFFSetField(out, TIFFTAG_PHOTOMETRIC,
-					     PHOTOMETRIC_RGB);
-		} else
-			TIFFSetField(out, TIFFTAG_PHOTOMETRIC,
-				     input_photometric);
-	    }
-        }
+		if (input_photometric == PHOTOMETRIC_RGB &&
+		    jpegcolormode == JPEGCOLORMODE_RGB)
+		  TIFFSetField(out, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_YCBCR);
+		else
+		  TIFFSetField(out, TIFFTAG_PHOTOMETRIC, input_photometric);
+	}
 	else if (compression == COMPRESSION_SGILOG
 		 || compression == COMPRESSION_SGILOG24)
 		TIFFSetField(out, TIFFTAG_PHOTOMETRIC,