fixup! Ensure cluster cache is properly clean in case of exception in…

… constructor.

Calling non static member from constructor try block handler is UB.
Accessing this (witohut dereferencing it) is kind of gray area as
(See https://stackoverflow.com/questions/79463018/can-i-access-this-from-contructor-try-block-handler)

So the try/catch has been moved to a more classic try/catch block as
only a specific part of the contructor can create (and cache) clusters.

src/fileimpl.cpp

@@ -188,7 +188,7 @@ class Grouping
   {}
 #endif
 
-  FileImpl::FileImpl(std::shared_ptr<FileCompound> _zimFile) try
+  FileImpl::FileImpl(std::shared_ptr<FileCompound> _zimFile)
     : zimFile(_zimFile),
       zimReader(makeFileReader(zimFile)),
       direntReader(new DirentReader(zimReader)),
@@ -248,33 +248,42 @@ class Grouping
       const_cast<entry_index_t&>(m_endUserEntry) = getCountArticles();
     }
 
-    auto result = tmp_direntLookup.find('X', "listing/titleOrdered/v1");
-    if (result.first) {
-      mp_titleDirentAccessor = getTitleAccessorV1(result.second);
-    }
 
-    if (!mp_titleDirentAccessor) {
-      if (!header.hasTitleListingV0()) {
-        throw ZimFileFormatError("Zim file doesn't contain a title ordered index");
+    // Following code will may create cluster and
+    try {
+      auto result = tmp_direntLookup.find('X', "listing/titleOrdered/v1");
+      if (result.first) {
+        mp_titleDirentAccessor = getTitleAccessorV1(result.second);
       }
-      offset_t titleOffset(header.getTitleIdxPos());
-      zsize_t  titleSize(sizeof(entry_index_type)*header.getArticleCount());
-      mp_titleDirentAccessor = getTitleAccessor(titleOffset, titleSize, "Title index table");
-      const_cast<bool&>(m_hasFrontArticlesIndex) = false;
-    }
-    m_byTitleDirentLookup.reset(new ByTitleDirentLookup(mp_titleDirentAccessor.get()));
 
-    readMimeTypes();
-  } catch (...) {
-    getClusterCache().drop_all([=](const std::tuple<FileImpl*, cluster_index_type>& key) {return std::get<0>(key) == this;});
-    throw;
+      if (!mp_titleDirentAccessor) {
+        if (!header.hasTitleListingV0()) {
+          throw ZimFileFormatError("Zim file doesn't contain a title ordered index");
+        }
+        offset_t titleOffset(header.getTitleIdxPos());
+        zsize_t  titleSize(sizeof(entry_index_type)*header.getArticleCount());
+        mp_titleDirentAccessor = getTitleAccessor(titleOffset, titleSize, "Title index table");
+        const_cast<bool&>(m_hasFrontArticlesIndex) = false;
+      }
+      m_byTitleDirentLookup.reset(new ByTitleDirentLookup(mp_titleDirentAccessor.get()));
+
+      readMimeTypes();
+    } catch (...) {
+      dropCachedCluster();
+      throw;
+    }
   }
 
   FileImpl::~FileImpl() {
     // We have to clean the global cache for our clusters.
+    dropCachedCluster();
+  }
+
+  void FileImpl::dropCachedCluster() const {
     getClusterCache().drop_all([=](const std::tuple<FileImpl*, cluster_index_type>& key) {return std::get<0>(key) == this;});
   }
 
+
   std::unique_ptr<IndirectDirentAccessor> FileImpl::getTitleAccessorV1(const entry_index_t idx)
   {
     auto dirent = mp_pathDirentAccessor->getDirent(idx);

src/fileimpl.h

@@ -166,6 +166,8 @@ namespace zim
       explicit FileImpl(std::shared_ptr<FileCompound> zimFile);
       FileImpl(std::shared_ptr<FileCompound> zimFile, offset_t offset, zsize_t size);
 
+      void dropCachedCluster() const;
+
       std::unique_ptr<IndirectDirentAccessor> getTitleAccessorV1(const entry_index_t idx);
       std::unique_ptr<IndirectDirentAccessor> getTitleAccessor(const offset_t offset, const zsize_t size, const std::string& name);