Fix for wrong integer conversion

Fixes #405

Author: joto

include/osmium/io/detail/pbf_input_format.hpp

@@ -100,13 +100,6 @@ namespace osmium {
                     m_input_buffer.erase(0, size);
                 }
 
-                static uint32_t get_size_in_network_byte_order(const char* d) noexcept {
-                    return (static_cast<uint32_t>(d[3])) |
-                           (static_cast<uint32_t>(d[2]) <<  8U) |
-                           (static_cast<uint32_t>(d[1]) << 16U) |
-                           (static_cast<uint32_t>(d[0]) << 24U);
-                }
-
                 static uint32_t check_size(uint32_t size) {
                     if (size > static_cast<uint32_t>(max_blob_header_size)) {
                         throw osmium::pbf_error{"invalid BlobHeader size (> max_blob_header_size)"};
@@ -256,6 +249,13 @@ namespace osmium {
 
             public:
 
+                static uint32_t get_size_in_network_byte_order(const char* d) noexcept {
+                    return (static_cast<uint32_t>(static_cast<uint8_t>(d[3]))) |
+                           (static_cast<uint32_t>(static_cast<uint8_t>(d[2])) <<  8U) |
+                           (static_cast<uint32_t>(static_cast<uint8_t>(d[1])) << 16U) |
+                           (static_cast<uint32_t>(static_cast<uint8_t>(d[0])) << 24U);
+                }
+
                 explicit PBFParser(parser_arguments& args) :
                     Parser(args),
                     m_offset_ptr(args.offset_ptr),

test/t/io/test_pbf.cpp

@@ -3,9 +3,12 @@
 #include "utils.hpp"
 
 #include <osmium/io/pbf_input.hpp>
+#include <osmium/io/detail/pbf_input_format.hpp>
 #include <osmium/io/reader.hpp>
 #include <osmium/osm/object.hpp>
 
+#include <array>
+
 TEST_CASE("Get supported PBF compression types") {
     const auto types = osmium::io::supported_pbf_compression_types();
     REQUIRE(types.size() >= 2);
@@ -50,3 +53,17 @@ TEST_CASE("Read PBF file with version=-1 and changeset=-1 and DenseNodes (writte
     REQUIRE(object.version() == 0);
     REQUIRE(object.changeset() == 0);
 }
+
+TEST_CASE("get size in network byte order") {
+    const std::array<char, 4> data1 = { 0, 0, 0, 1 };
+    REQUIRE(osmium::io::detail::PBFParser::get_size_in_network_byte_order(data1.data()) == 1);
+
+    const std::array<char, 4> data127 = { 0, 0, 0, 127 };
+    REQUIRE(osmium::io::detail::PBFParser::get_size_in_network_byte_order(data127.data()) == 127);
+
+    const std::array<char, 4> data128 = { 0, 0, 0, static_cast<char>(128) };
+    REQUIRE(osmium::io::detail::PBFParser::get_size_in_network_byte_order(data128.data()) == 128);
+
+    const std::array<char, 4> data65535 = { 0, 0, static_cast<char>(255), static_cast<char>(255) };
+    REQUIRE(osmium::io::detail::PBFParser::get_size_in_network_byte_order(data65535.data()) == 65535);
+}