Merge pull request #175 from scratchcpp/zip_api

Add internal API for reading ZIP files

Author: adazem009

src/internal/CMakeLists.txt

@@ -4,4 +4,6 @@ target_sources(scratchcpp
     scratch3reader.cpp
     scratch3reader.h
     reader_common.h
+    zipreader.cpp
+    zipreader.h
 )

src/internal/iprojectreader.h

@@ -34,6 +34,7 @@ class IProjectReader
         virtual std::vector<std::string> extensions() = 0;
 
     protected:
+        virtual void printErr(const std::string &errStr) final { std::cerr << "Failed to read project: " << errStr << std::endl; }
         virtual void printErr(const std::string &errStr, const char *what) final { std::cerr << "Failed to read project: " << errStr << std::endl << what << std::endl; }
 
     private:

src/internal/scratch3reader.cpp

@@ -14,6 +14,7 @@
 
 #include "scratch3reader.h"
 #include "reader_common.h"
+#include "zipreader.h"
 
 using namespace libscratchcpp;
 using json = nlohmann::json;
@@ -299,14 +300,9 @@ bool Scratch3Reader::load()
         else
             printErr(std::string("could not parse ") + step, e.what());
 
-        // Close the zip file
-        zip_close(m_zip);
-
         return false;
     }
 
-    // Close the zip file
-    zip_close(m_zip);
     return true;
 }
 
@@ -352,37 +348,15 @@ std::vector<std::string> Scratch3Reader::extensions()
 
 void Scratch3Reader::read()
 {
-    // Open the zip file
-    unsigned char *buf;
-    size_t bufsize;
-    m_zip = zip_open(fileName().c_str(), 0, 'r');
-    if (!m_zip) {
-        std::cerr << "Failed to open project file" << std::endl;
-        return;
-    }
-
-    // Extract project.json
-    zip_entry_open(m_zip, "project.json");
-    bufsize = zip_entry_size(m_zip);
-    buf = (unsigned char *)calloc(sizeof(unsigned char), bufsize);
-    zip_entry_noallocread(m_zip, (void *)buf, bufsize);
-    zip_entry_close(m_zip);
-    std::string str(reinterpret_cast<char const *>(buf));
-    free(buf);
-
-    // Remove garbage after the JSON
-    int end;
-    for (end = str.size(); end >= 0; end--) {
-        char ch = str[end];
-        if (ch == '}')
-            break;
-    }
-    std::string out = str.substr(0, end + 1);
-
-    // Parse the JSON
-    try {
-        m_json = json::parse(out);
-    } catch (std::exception &e) {
-        printErr("invalid JSON file", e.what());
-    }
+    // Read project.json
+    ZipReader reader(fileName());
+    if (reader.open()) {
+        // Parse the JSON
+        try {
+            m_json = json::parse(reader.readFileToString("project.json"));
+        } catch (std::exception &e) {
+            printErr("invalid JSON file", e.what());
+        }
+    } else
+        printErr("could not read " + fileName());
 }

src/internal/scratch3reader.h

@@ -4,7 +4,6 @@
 
 #include "iprojectreader.h"
 #include <nlohmann/json.hpp>
-#include <zip.h>
 
 namespace libscratchcpp
 {
@@ -21,7 +20,6 @@ class Scratch3Reader : public IProjectReader
 
     private:
         void read();
-        struct zip_t *m_zip = nullptr;
         nlohmann::json m_json = "";
         std::vector<std::shared_ptr<Target>> m_targets;
         std::vector<std::shared_ptr<Broadcast>> m_broadcasts;

src/internal/zipreader.cpp

@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: Apache-2.0
+
+#include "zipreader.h"
+
+using namespace libscratchcpp;
+
+ZipReader::ZipReader(const std::string &fileName) :
+    m_fileName(fileName)
+{
+}
+
+ZipReader::ZipReader(const char *fileName) :
+    ZipReader(std::string(fileName))
+{
+}
+
+ZipReader::~ZipReader()
+{
+    close();
+}
+
+bool ZipReader::open()
+{
+    m_zip = zip_open(m_fileName.c_str(), 0, 'r');
+    return m_zip;
+}
+
+void ZipReader::close()
+{
+    if (m_zip)
+        zip_close(m_zip);
+
+    m_zip = nullptr;
+}
+
+size_t ZipReader::readFile(const std::string &fileName, void **buf)
+{
+    if (!m_zip) {
+        buf = nullptr;
+        return 0;
+    }
+
+    size_t bufsize = 0;
+    zip_entry_open(m_zip, fileName.c_str());
+    zip_entry_read(m_zip, buf, &bufsize);
+    zip_entry_close(m_zip);
+
+    return bufsize;
+}
+
+std::string ZipReader::readFileToString(const std::string &fileName)
+{
+    void *buf = nullptr;
+    size_t bufsize = readFile(fileName, &buf);
+
+    if (buf) {
+        std::string ret(reinterpret_cast<char *>(buf), bufsize);
+        free(buf);
+
+        return ret;
+    }
+
+    return "";
+}

src/internal/zipreader.h

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include <string>
+#include <zip.h>
+
+namespace libscratchcpp
+{
+
+class ZipReader
+{
+    public:
+        ZipReader(const std::string &fileName);
+        ZipReader(const char *fileName);
+        ZipReader(const ZipReader &) = delete;
+        ~ZipReader();
+
+        bool open();
+        void close();
+
+        size_t readFile(const std::string &fileName, void **buf);
+        std::string readFileToString(const std::string &fileName);
+
+    private:
+        std::string m_fileName;
+        struct zip_t *m_zip = nullptr;
+};
+
+} // namespace libscratchcpp

test/zip/CMakeLists.txt

@@ -5,6 +5,7 @@ add_executable(
 
 target_link_libraries(
   zip_test
+  scratchcpp
   GTest::gtest_main
   zip
 )

test/zip/zip_test.cpp

@@ -1,34 +1,19 @@
-#include <gtest/gtest.h>
-#include <zip.h>
-#include <filesystem>
+#include <internal/zipreader.h>
 #include "../common.h"
 
-std::string readSb3Json(const std::string &fileName)
+using namespace libscratchcpp;
+
+inline std::string readSb3Json(const std::string &fileName)
+{
+    ZipReader reader(fileName);
+    reader.open();
+
+    return reader.readFileToString("project.json");
+}
+
+TEST(ZipTest, NonexistentProject)
 {
-    // TODO: Move this to a class and use it in Scratch3Reader
-    // Open the zip file
-    unsigned char *buf;
-    size_t bufsize;
-    struct zip_t *zip = zip_open(fileName.c_str(), 0, 'r');
-
-    // Extract project.json
-    zip_entry_open(zip, "project.json");
-    bufsize = zip_entry_size(zip);
-    buf = (unsigned char *)calloc(sizeof(unsigned char), bufsize);
-    zip_entry_noallocread(zip, (void *)buf, bufsize);
-    zip_entry_close(zip);
-    std::string str(reinterpret_cast<char const *>(buf));
-    free(buf);
-
-    // Remove garbage after the JSON
-    int end;
-    for (end = str.size(); end >= 0; end--) {
-        char ch = str[end];
-        if (ch == '}') {
-            break;
-        }
-    }
-    return str.substr(0, end + 1);
+    ASSERT_TRUE(readSb3Json("idontexist.sb3").empty());
 }
 
 TEST(ZipTest, EmptyProject)