From 1b5c1431973d85acd36a68709063ac18241d5bde Mon Sep 17 00:00:00 2001
From: Michal Simon <michal.simon@cern.ch>
Date: Tue, 22 Dec 2020 00:05:11 +0100
Subject: [PATCH] [XrdEc] Parse metadata file, part 1.

---
 src/XrdEc/XrdEcReader.hh | 52 +++++++++++++++++++++++++++++++++++-----
 src/XrdZip/XrdZipLFH.hh  |  4 ++++
 2 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/src/XrdEc/XrdEcReader.hh b/src/XrdEc/XrdEcReader.hh
index 35b92e972f3..c28da0b5b5b 100644
--- a/src/XrdEc/XrdEcReader.hh
+++ b/src/XrdEc/XrdEcReader.hh
@@ -12,7 +12,14 @@
 
 #include "XrdCl/XrdClFileOperations.hh"
 
+#include "XrdZip/XrdZipLFH.hh"
+#include "XrdZip/XrdZipCDFH.hh"
+#include "XrdZip/XrdZipUtils.hh"
+
+#include "XrdOuc/XrdOucCRC32C.hh"
+
 #include <string>
+#include <iostream>
 
 namespace XrdEc
 {
@@ -40,7 +47,7 @@ namespace XrdEc
           opens.emplace_back( XrdCl::Open( *dataarchs[i], url, XrdCl::OpenFlags::Read ) );
         }
         // in parallel open the data files and read the metadata
-        XrdCl::Pipeline p = XrdCl::Parallel( ReadMetadata( 0 ), XrdCl::Parallel( opens ) );
+        XrdCl::Pipeline p = XrdCl::Parallel( ReadMetadata( 0 ), XrdCl::Parallel( opens ) ) >> handler;
         XrdCl::Async( std::move( p ) );
       }
 
@@ -54,8 +61,8 @@ namespace XrdEc
         // prepare the URL for Open operation
         std::string url = objcfg.plgr[index] + objcfg.obj + ".metadata.zip";
         // arguments for the Read operation
-        XrdCl::Fwd<uint32_t> rdsize( 0 );
-        XrdCl::Fwd<void*>    rdbuff( nullptr );
+        XrdCl::Fwd<uint32_t> rdsize;
+        XrdCl::Fwd<void*>    rdbuff;
 
         return XrdCl::Open( *file, url, XrdCl::OpenFlags::Read ) >>
                  [=]( XrdCl::XRootDStatus &st, XrdCl::StatInfo &info )
@@ -100,13 +107,46 @@ namespace XrdEc
 
       bool ParseMetadata( XrdCl::ChunkInfo &ch )
       {
-        // TODO
-        return false;
+        std::cout << __func__ << std::endl;
+        const size_t mincnt = objcfg.nbdata + objcfg.nbparity;
+        const size_t maxcnt = objcfg.plgr.size();
+
+        char    *buffer = reinterpret_cast<char*>( ch.buffer );
+        size_t  length = ch.length;
+
+        for( size_t i = 0; i < maxcnt; ++i )
+        {
+          uint32_t signature = XrdZip::to<uint32_t>( buffer );
+          if( signature != XrdZip::LFH::lfhSign )
+          {
+            if( i + 1 < mincnt ) return false;
+            break;
+          }
+          XrdZip::LFH lfh( buffer );
+          // check if we are not reading passed the end of the buffer
+          if( lfh.lfhSize + lfh.uncompressedSize > length ) return false;
+          buffer += lfh.lfhSize;
+          length -= lfh.lfhSize;
+          // verify the checksum
+          uint32_t crc32val = crc32c( 0, buffer, lfh.uncompressedSize );
+          if( crc32val != lfh.ZCRC32 ) return false;
+          XrdZip::CDFH::Parse( buffer, lfh.uncompressedSize, cdrecs );
+          buffer += lfh.uncompressedSize;
+          length -= lfh.uncompressedSize;
+        }
+
+        auto itr = cdrecs.begin();
+        for( ; itr != cdrecs.end() ; ++itr )
+        {
+          std::cout << itr->first << " : " << itr->second.get()->filename << std::endl;
+        }
+
+        return true;
       }
 
       ObjCfg &objcfg;
       std::vector<std::shared_ptr<XrdCl::File>>  dataarchs;
-
+      XrdZip::cdrecs_t cdrecs;
   };
 
 } /* namespace XrdEc */
diff --git a/src/XrdZip/XrdZipLFH.hh b/src/XrdZip/XrdZipLFH.hh
index 5e7c49f16ce..268595bd670 100644
--- a/src/XrdZip/XrdZipLFH.hh
+++ b/src/XrdZip/XrdZipLFH.hh
@@ -70,6 +70,10 @@ namespace XrdZip
     //-------------------------------------------------------------------------
     LFH( const char *buffer )
     {
+      // check if the buffer contains a LFH record
+      uint32_t signature = 0;
+      from_buffer( signature, buffer );
+      if( signature != lfhSign ) throw bad_data();
       // parse LFH filds
       from_buffer( minZipVersion, buffer );
       from_buffer( generalBitFlag, buffer );