From 07ab90039380344a308d0a9446564e5474697a02 Mon Sep 17 00:00:00 2001
From: Eric Fischer <enf@pobox.com>
Date: Fri, 13 Jul 2018 17:02:49 -0700
Subject: [PATCH] Report decompression errors in tippecanoe-decode

---
 mvt.cpp | 52 +++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 39 insertions(+), 13 deletions(-)

diff --git a/mvt.cpp b/mvt.cpp
index f5028e7..b069302 100644
--- a/mvt.cpp
+++ b/mvt.cpp
@@ -34,25 +34,49 @@ int decompress(std::string const &input, std::string &output) {
 	inflate_s.avail_in = 0;
 	inflate_s.next_in = Z_NULL;
 	if (inflateInit2(&inflate_s, 32 + 15) != Z_OK) {
-		fprintf(stderr, "error: %s\n", inflate_s.msg);
+		fprintf(stderr, "Decompression error: %s\n", inflate_s.msg);
 	}
 	inflate_s.next_in = (Bytef *) input.data();
 	inflate_s.avail_in = input.size();
-	size_t length = 0;
-	do {
-		output.resize(length + 2 * input.size());
-		inflate_s.avail_out = 2 * input.size();
-		inflate_s.next_out = (Bytef *) (output.data() + length);
-		int ret = inflate(&inflate_s, Z_FINISH);
-		if (ret != Z_STREAM_END && ret != Z_OK && ret != Z_BUF_ERROR) {
-			fprintf(stderr, "error: %s\n", inflate_s.msg);
+	inflate_s.next_out = (Bytef *) output.data();
+	inflate_s.avail_out = output.size();
+
+	while (true) {
+		size_t existing_output = inflate_s.next_out - (Bytef *) output.data();
+
+		output.resize(existing_output + 2 * inflate_s.avail_in + 100);
+		inflate_s.next_out = (Bytef *) output.data() + existing_output;
+		inflate_s.avail_out = output.size() - existing_output;
+
+		int ret = inflate(&inflate_s, 0);
+		if (ret < 0) {
+			fprintf(stderr, "Decompression error: ");
+			if (ret == Z_DATA_ERROR) {
+				fprintf(stderr, "data error");
+			}
+			if (ret == Z_STREAM_ERROR) {
+				fprintf(stderr, "stream error");
+			}
+			if (ret == Z_MEM_ERROR) {
+				fprintf(stderr, "out of memory");
+			}
+			if (ret == Z_BUF_ERROR) {
+				fprintf(stderr, "no data in buffer");
+			}
+			fprintf(stderr, "\n");
 			return 0;
 		}
 
-		length += (2 * input.size() - inflate_s.avail_out);
-	} while (inflate_s.avail_out == 0);
+		if (ret == Z_STREAM_END) {
+			break;
+		}
+
+		// ret must be Z_OK or Z_NEED_DICT;
+		// continue decompresing
+	}
+
+	output.resize(inflate_s.next_out - (Bytef *) output.data());
 	inflateEnd(&inflate_s);
-	output.resize(length);
 	return 1;
 }
 
@@ -90,7 +114,9 @@ bool mvt_tile::decode(std::string &message, bool &was_compressed) {
 
 	if (is_compressed(message)) {
 		std::string uncompressed;
-		decompress(message, uncompressed);
+		if (decompress(message, uncompressed) == 0) {
+			exit(EXIT_FAILURE);
+		}
 		src = uncompressed;
 		was_compressed = true;
 	} else {