fix(zip): read an entry name with a leading slash as relative

CHANGELOG.md

@@ -16,6 +16,10 @@ The release run heads these entries with the version and opens a fresh
 
 ## Unreleased
 
+- **Fix**: a zip entry name with a leading slash is read relative to the
+  archive root rather than throwing, and one named `/` alone is dropped. An
+  `.odt` carrying such an entry now opens; LibreOffice still refuses it.
+
 - The rendered sheet exposes `odr.editing`: `enable()` / `disable()` turn the
   mode on, `lockAt()` answers for a cell, and a refusal reaches the host as
   `odr.onEditRefused` / `odr.onEditModeChange`, whose codes share the space

src/odr/internal/zip/zip_archive.cpp

@@ -44,6 +44,10 @@ ZipArchive::ZipArchive() = default;
 ZipArchive::ZipArchive(const std::shared_ptr<util::Archive> &archive) {
   for (auto &&entry : *archive) {
     RelPath path(entry.path());
+    // an entry named "/" addresses nothing
+    if (path.empty()) {
+      continue;
+    }
     if (entry.is_file()) {
       std::uint8_t compression_level = 6;
       if (entry.method() == util::Method::STORED) {

src/odr/internal/zip/zip_util.cpp

@@ -132,7 +132,8 @@ RelPath Archive::Entry::path() const {
   std::array<char, MZ_ZIP_MAX_ARCHIVE_FILENAME_SIZE> filename{};
   mz_zip_reader_get_filename(m_archive->zip(), m_index, filename.data(),
                              static_cast<mz_uint>(filename.size()));
-  return RelPath(filename.data());
+  // a leading slash is malformed (APPNOTE.TXT 4.4.17.1) and read away
+  return Path(filename.data()).make_relative();
 }
 
 Method Archive::Entry::method() const {

test/data.cmake

@@ -12,7 +12,7 @@ odr_test_data(
 odr_test_data(
         PATH "input/odr-private"
         URL "https://github.com/opendocument-app/OpenDocument.test-private.git"
-        REVISION "d0bedc89b67e73a2e4113f96f27d1d1cdf30c69f")
+        REVISION "c4efe97d67c9a12aa08965d696a0cb7a3dc4d025")
 
 odr_test_data(
         PATH "reference-output/odr-public"
@@ -22,4 +22,4 @@ odr_test_data(
 odr_test_data(
         PATH "reference-output/odr-private"
         URL "https://github.com/opendocument-app/OpenDocument.test-private.output.git"
-        REVISION "c43ef03e9ca239489141a8d91c0187ed9602436a")
+        REVISION "666ce5a24a1a2d4f74b1abf0f004c0778e9ebddd")

test/src/internal/zip/zip_archive_test.cpp

@@ -1,5 +1,6 @@
 #include <odr/exceptions.hpp>
 
+#include <odr/internal/abstract/filesystem.hpp>
 #include <odr/internal/common/file.hpp>
 #include <odr/internal/zip/zip_archive.hpp>
 #include <odr/internal/zip/zip_file.hpp>
@@ -9,9 +10,11 @@
 
 #include <gtest/gtest.h>
 
+#include <algorithm>
 #include <cstdint>
 #include <filesystem>
 #include <fstream>
+#include <iterator>
 #include <memory>
 #include <string>
 #include <thread>
@@ -130,6 +133,41 @@ TEST(ZipArchive, create_order) {
   }
 }
 
+/// A leading slash, forbidden by APPNOTE.TXT 4.4.17.1, is read away; a name
+/// that is nothing but the root addresses no entry.
+TEST(ZipArchive, absolute_entry_name) {
+  const std::string path =
+      (std::filesystem::current_path() / "absolute-name.zip").string();
+
+  {
+    // miniz refuses the name, so a placeholder goes in and is patched out
+    mz_zip_archive archive{};
+    ASSERT_TRUE(mz_zip_writer_init_file(&archive, path.c_str(), 0));
+    ASSERT_TRUE(mz_zip_writer_add_mem(&archive, "@", nullptr, 0, 0));
+    ASSERT_TRUE(mz_zip_writer_add_mem(&archive, "@one.txt", "abc", 3, 0));
+    ASSERT_TRUE(mz_zip_writer_finalize_archive(&archive));
+    ASSERT_TRUE(mz_zip_writer_end(&archive));
+
+    std::string data;
+    {
+      std::ifstream in(path, std::ios::binary);
+      data.assign(std::istreambuf_iterator<char>(in),
+                  std::istreambuf_iterator<char>());
+    }
+    std::ranges::replace(data, '@', '/');
+    std::ofstream out(path, std::ios::binary);
+    out.write(data.data(), static_cast<std::streamsize>(data.size()));
+  }
+
+  const auto zip =
+      std::make_shared<util::Archive>(std::make_shared<DiskFile>(path));
+  EXPECT_EQ(3, zip->find(RelPath("one.txt"))->file()->size());
+
+  const ZipArchive read(zip);
+  EXPECT_EQ(1, std::distance(read.begin(), read.end()));
+  EXPECT_TRUE(read.as_filesystem()->is_file(AbsPath("/one.txt")));
+}
+
 /// The read callback has to be re-entrant, for a memory and a stream source.
 TEST(ZipArchive, concurrent_entry_reads) {
   const std::string path =