Bugfix: Terminate called on full buffer.

A full non-auto-growing buffer could lead to the program terminating
instead of a thrown exception. Reason was that the number of bytes
written to the buffer was not tracked properly when appending tag keys
and values to the buffer. The destructor on the TagListBuilder would
then throw another exception which terminates the program. This should
fix this problem by keeping the number of bytes written to the buffer
correctly.

See #189.

include/osmium/builder/builder.hpp

@@ -167,6 +167,20 @@ namespace osmium {
                 return length;
             }
 
+            /**
+             * Append data to buffer and append an additional \0.
+             *
+             * @param data Pointer to data.
+             * @param length Length of data in bytes.
+             * @returns The number of bytes appended (length + 1).
+             */
+            osmium::memory::item_size_type append_with_zero(const char* data, const osmium::memory::item_size_type length) {
+                unsigned char* target = reserve_space(length + 1);
+                std::copy_n(reinterpret_cast<const unsigned char*>(data), length, target);
+                target[length] = '\0';
+                return length + 1;
+            }
+
             /**
              * Append \0-terminated string to buffer.
              *
@@ -180,9 +194,11 @@ namespace osmium {
             /**
              * Append '\0' to the buffer.
              *
+             * @deprecated Use append_with_zero() instead.
+             *
              * @returns The number of bytes appended (always 1).
              */
-            osmium::memory::item_size_type append_zero() {
+            OSMIUM_DEPRECATED osmium::memory::item_size_type append_zero() {
                 *reserve_space(1) = '\0';
                 return 1;
             }

include/osmium/builder/osm_object_builder.hpp

@@ -99,7 +99,8 @@ namespace osmium {
                 if (std::strlen(value) > osmium::max_osm_string_length) {
                     throw std::length_error("OSM tag value is too long");
                 }
-                add_size(append(key) + append(value));
+                add_size(append(key));
+                add_size(append(value));
             }
 
             /**
@@ -117,8 +118,8 @@ namespace osmium {
                 if (value_length > osmium::max_osm_string_length) {
                     throw std::length_error("OSM tag value is too long");
                 }
-                add_size(append(key,   osmium::memory::item_size_type(key_length))   + append_zero() +
-                         append(value, osmium::memory::item_size_type(value_length)) + append_zero());
+                add_size(append_with_zero(key,   osmium::memory::item_size_type(key_length)));
+                add_size(append_with_zero(value, osmium::memory::item_size_type(value_length)));
             }
 
             /**
@@ -134,8 +135,8 @@ namespace osmium {
                 if (value.size() > osmium::max_osm_string_length) {
                     throw std::length_error("OSM tag value is too long");
                 }
-                add_size(append(key.data(),   osmium::memory::item_size_type(key.size())   + 1) +
-                         append(value.data(), osmium::memory::item_size_type(value.size()) + 1));
+                add_size(append(key.data(),   osmium::memory::item_size_type(key.size())   + 1));
+                add_size(append(value.data(), osmium::memory::item_size_type(value.size()) + 1));
             }
 
             /**
@@ -144,7 +145,8 @@ namespace osmium {
              * @param tag Tag.
              */
             void add_tag(const osmium::Tag& tag) {
-                add_size(append(tag.key()) + append(tag.value()));
+                add_size(append(tag.key()));
+                add_size(append(tag.value()));
             }
 
             /**
@@ -226,7 +228,7 @@ namespace osmium {
                     throw std::length_error("OSM relation member role is too long");
                 }
                 member.set_role_size(osmium::string_size_type(length) + 1);
-                add_size(append(role, osmium::memory::item_size_type(length)) + append_zero());
+                add_size(append_with_zero(role, osmium::memory::item_size_type(length)));
                 add_padding(true);
             }
 
@@ -310,7 +312,7 @@ namespace osmium {
                     throw std::length_error("OSM user name is too long");
                 }
                 comment.set_user_size(osmium::string_size_type(length) + 1);
-                add_size(append(user, osmium::memory::item_size_type(length)) + append_zero());
+                add_size(append_with_zero(user, osmium::memory::item_size_type(length)));
             }
 
             void add_text(osmium::ChangesetComment& comment, const char* text, const size_t length) {
@@ -322,7 +324,7 @@ namespace osmium {
                     throw std::length_error("OSM changeset comment is too long");
                 }
                 comment.set_text_size(osmium::string_size_type(length) + 1);
-                add_size(append(text, osmium::memory::item_size_type(length)) + append_zero());
+                add_size(append_with_zero(text, osmium::memory::item_size_type(length)));
                 add_padding(true);
             }