[core] Simplify asset:// implementation

* Move asset:// URL handling to DefaultFileSource.
* AssetFileSource implements FileSource interface and follows familiar implementation patterns.
* Move default implementation to platform/default, zip implementation to platform/android.
* Don't bother with modified / expires / etag -- assets are not cached so it doesn't matter.
* Don't bother with interleaving individual IO calls on the implementation thread. That adds a lot of complexity for very little benefit.

1 files changed, 79 insertions, 0 deletions

diff --git a/platform/default/asset_file_source.cpp b/platform/default/asset_file_source.cpp
new file mode 100644
index 0000000000..5aa5730c94
--- /dev/null
+++ b/platform/default/asset_file_source.cpp
@@ -0,0 +1,79 @@
+#include <mbgl/storage/asset_file_source.hpp>
+#include <mbgl/storage/response.hpp>
+#include <mbgl/util/string.hpp>
+#include <mbgl/util/thread.hpp>
+#include <mbgl/util/url.hpp>
+#include <mbgl/util/util.hpp>
+#include <mbgl/util/io.hpp>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+namespace mbgl {
+
+class AssetFileRequest : public FileRequest {
+public:
+    AssetFileRequest(std::unique_ptr<WorkRequest> workRequest_)
+        : workRequest(std::move(workRequest_)) {
+    }
+
+    std::unique_ptr<WorkRequest> workRequest;
+};
+
+class AssetFileSource::Impl {
+public:
+    Impl(const std::string& root_)
+        : root(root_) {
+    }
+
+    void request(const std::string& url, FileSource::Callback callback) {
+        std::string path;
+
+        if (url.size() <= 8 || url[8] == '/') {
+            // This is an empty or absolute path.
+            path = mbgl::util::percentDecode(url.substr(8));
+        } else {
+            // This is a relative path. Prefix with the application root.
+            path = root + "/" + mbgl::util::percentDecode(url.substr(8));
+        }
+
+        Response response;
+
+        struct stat buf;
+        int result = stat(path.c_str(), &buf);
+
+        if (result == 0 && S_ISDIR(buf.st_mode)) {
+            response.error = std::make_unique<Response::Error>(Response::Error::Reason::NotFound);
+        } else if (result == -1 && errno == ENOENT) {
+            response.error = std::make_unique<Response::Error>(Response::Error::Reason::NotFound);
+        } else {
+            try {
+                response.data = std::make_shared<std::string>(util::read_file(path));
+            } catch (...) {
+                response.error = std::make_unique<Response::Error>(
+                    Response::Error::Reason::Other,
+                    util::toString(std::current_exception()));
+            }
+        }
+
+        callback(response);
+    }
+
+private:
+    std::string root;
+};
+
+AssetFileSource::AssetFileSource(const std::string& root)
+    : thread(std::make_unique<util::Thread<Impl>>(
+        util::ThreadContext{"AssetFileSource", util::ThreadType::Worker, util::ThreadPriority::Regular},
+        root.empty() ? platform::assetRoot() : root)) {
+}
+
+AssetFileSource::~AssetFileSource() = default;
+
+std::unique_ptr<FileRequest> AssetFileSource::request(const Resource& resource, Callback callback) {
+    return std::make_unique<AssetFileRequest>(thread->invokeWithCallback(&Impl::request, callback, resource.url));
+}
+
+} // namespace mbgl