Implement zip::read_file() – Read file in archive; add test.

Also added zip::open_file() and zip::close_file() to deduplicate code.

src/main.cpp

@@ -80,7 +80,10 @@ int main(int argc, char *argv[])
             {
                 for (const auto &entry : epubgrep::zip::list(file))
                 {
-                    cout << "    " << entry << '\n';
+                    cout << "    " << entry;
+                    cout << "\n      CONTENT:\n";
+                    cout << "START" << epubgrep::zip::read_file(file, entry)
+                         << "END\n";
                 }
             }
             catch (const epubgrep::zip::exception &e)

src/zip.cpp

@@ -24,6 +24,8 @@
 #include <fmt/format.h>
 #include <fmt/ostream.h> // For compatibility with fmt 4.
 
+#include <cstdlib>
+#include <cstring>
 #include <string>
 #include <vector>
 
@@ -35,16 +37,7 @@ using fmt::format;
 
 std::vector<std::string> list(const fs::path &filepath)
 {
-    auto *zipfile{archive_read_new()};
-    archive_read_support_filter_all(zipfile);
-    archive_read_support_format_all(zipfile);
-
-    auto result{archive_read_open_filename(zipfile, filepath.c_str(), 10240)};
-    if (result != ARCHIVE_OK)
-    {
-        throw exception{format(translate("Could not open {0:s}.").str(),
-                               filepath.string())};
-    }
+    auto *zipfile{open_file(filepath)};
 
     struct archive_entry *entry{};
     std::vector<std::string> toc;
@@ -53,15 +46,69 @@ std::vector<std::string> list(const fs::path &filepath)
         toc.emplace_back(archive_entry_pathname_utf8(entry));
         archive_read_data_skip(zipfile);
     }
+    close_file(zipfile, filepath);
 
-    result = archive_read_free(zipfile);
+    return toc;
+}
+
+std::string read_file(const fs::path &filepath, std::string_view entry_path)
+{
+    auto *zipfile{open_file(filepath)};
+
+    struct archive_entry *entry{};
+    while (archive_read_next_header(zipfile, &entry) == ARCHIVE_OK)
+    {
+        const auto *path{archive_entry_pathname_utf8(entry)};
+        if (std::strcmp(path, entry_path.data()) == 0)
+        {
+            const auto length{static_cast<size_t>(archive_entry_size(entry))};
+            std::string filecontents;
+            filecontents.resize(length);
+            auto result_length{static_cast<size_t>(
+                archive_read_data(zipfile, &filecontents[0], length))};
+
+            if (result_length != length)
+            {
+                throw exception{
+                    format(translate("Could not read {0:s} in {1:s}.").str(),
+                           entry_path, filepath.string())};
+            }
+
+            return filecontents;
+        }
+        archive_read_data_skip(zipfile);
+    }
+
+    close_file(zipfile, filepath);
+
+    throw exception{format(translate("{0:s} not found in {1:s}.").str(),
+                           entry_path, filepath.string())};
+}
+
+struct archive *open_file(const fs::path &filepath)
+{
+    auto *zipfile{archive_read_new()};
+    archive_read_support_filter_all(zipfile);
+    archive_read_support_format_zip(zipfile);
+
+    auto result{archive_read_open_filename(zipfile, filepath.c_str(), 10240)};
+    if (result != ARCHIVE_OK)
+    {
+        throw exception{format(translate("Could not open {0:s}.").str(),
+                               filepath.string())};
+    }
+
+    return zipfile;
+}
+
+void close_file(struct archive *zipfile, const fs::path &filepath)
+{
+    auto result{archive_read_free(zipfile)};
     if (result != ARCHIVE_OK)
     {
         throw exception{format(translate("Could not close {0:s}.").str(),
                                filepath.string())};
     }
-
-    return toc;
 }
 
 } // namespace epubgrep::zip

src/zip.hpp

@@ -19,8 +19,11 @@
 
 #include "fs-compat.hpp"
 
+#include <archive.h>
+
 #include <stdexcept>
 #include <string>
+#include <string_view>
 #include <vector>
 
 namespace epubgrep::zip
@@ -29,6 +32,15 @@ namespace epubgrep::zip
 //! List the contents of a zip file.
 std::vector<std::string> list(const fs::path &filepath);
 
+//! Read a file from a zip archive.
+std::string read_file(const fs::path &filepath, std::string_view entry_path);
+
+//! Open zip file and return handle.
+struct archive *open_file(const fs::path &filepath);
+
+//! Close zip file.
+void close_file(struct archive *zipfile, const fs::path &filepath);
+
 // It's std::runtime_error, but with another name.
 class exception : public std::runtime_error
 {

tests/test_zip.cpp

@@ -0,0 +1,72 @@
+#include "fs-compat.hpp"
+#include "zip.hpp"
+
+#include <catch.hpp>
+
+#include <clocale>
+#include <exception>
+#include <string>
+#include <vector>
+
+SCENARIO("Zip file handling works")
+{
+    GIVEN("Our test zip file")
+    {
+        fs::path zipfile{"test.zip"};
+        std::setlocale(LC_CTYPE, ""); // Needed for utf-8 support in libarchive.
+        bool exception{false};
+
+        REQUIRE(fs::exists(zipfile));
+
+        SECTION("list() doesn't fail and returns the right file list")
+        {
+            std::vector<std::string> filelist;
+
+            WHEN("We list the file contents")
+            {
+                try
+                {
+                    filelist = epubgrep::zip::list(zipfile);
+                }
+                catch (const std::exception &)
+                {
+                    exception = true;
+                }
+
+                THEN("No exception is thrown")
+                AND_THEN("It returns the TOC correctly")
+                {
+                    REQUIRE_FALSE(exception);
+                    REQUIRE(filelist.at(0) == "test folder/");
+                    REQUIRE(filelist.at(1) == "test folder/test file");
+                    REQUIRE(filelist.at(2) == "test folder/😊");
+                }
+            }
+        }
+
+        SECTION("read_file() doesn't fail and returns the right file contents")
+        {
+            std::string filecontents;
+
+            WHEN("We list the file contents")
+            {
+                try
+                {
+                    filecontents = epubgrep::zip::read_file(zipfile,
+                                                            "test folder/😊");
+                }
+                catch (const std::exception &)
+                {
+                    exception = true;
+                }
+
+                THEN("No exception is thrown")
+                AND_THEN("It returns the file contents correctly")
+                {
+                    REQUIRE_FALSE(exception);
+                    REQUIRE(filecontents == "📖\n\n📘📗📙\n");
+                }
+            }
+        }
+    }
+}

tests/test_zip_list.cpp

@@ -1,44 +0,0 @@
-#include "fs-compat.hpp"
-#include "zip.hpp"
-
-#include <catch.hpp>
-
-#include <clocale>
-#include <exception>
-#include <string>
-#include <vector>
-
-SCENARIO("epubgrep::zip::list() doesn't fail and returns the right file list")
-{
-    std::setlocale(LC_CTYPE, ""); // Needed for utf-8 support in libarchive.
-    bool exception{false};
-    std::vector<std::string> filelist;
-
-    GIVEN("Our test zip file")
-    {
-        fs::path zipfile{"test.zip"};
-
-        REQUIRE(fs::exists(zipfile));
-
-        WHEN("We list the file contents")
-        {
-            try
-            {
-                filelist = epubgrep::zip::list(zipfile);
-            }
-            catch (const std::exception &)
-            {
-                exception = true;
-            }
-
-            THEN("No exception is thrown")
-            AND_THEN("It returns the file contents correctly")
-            {
-                REQUIRE_FALSE(exception);
-                REQUIRE(filelist.at(0) == "test folder/");
-                REQUIRE(filelist.at(1) == "test folder/test file");
-                REQUIRE(filelist.at(2) == "test folder/😊");
-            }
-        }
-    }
-}