--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/PostgreSQL/PostgreSQLLargeObject.cpp	Wed Jul 04 08:16:29 2018 +0200
@@ -0,0 +1,226 @@
+/**
+ * Orthanc - A Lightweight, RESTful DICOM Store
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2018 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Affero General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Affero General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+// http://www.postgresql.org/docs/9.1/static/lo-interfaces.html#AEN33102
+
+#include "PostgreSQLLargeObject.h"
+
+#include <Core/Logging.h>
+#include <Core/OrthancException.h>
+
+#include <boost/lexical_cast.hpp>
+#include <libpq/libpq-fs.h>
+
+
+namespace OrthancDatabases
+{  
+  void PostgreSQLLargeObject::Create()
+  {
+    PGconn* pg = reinterpret_cast<PGconn*>(database_.pg_);
+
+    oid_ = lo_creat(pg, INV_WRITE);
+    if (oid_ == 0)
+    {
+      LOG(ERROR) << "PostgreSQL: Cannot create a large object";
+      database_.ThrowException(false);
+    }
+  }
+
+
+  void PostgreSQLLargeObject::Write(const void* data, 
+                                    size_t size)
+  {
+    static int MAX_CHUNK_SIZE = 16 * 1024 * 1024;
+
+    PGconn* pg = reinterpret_cast<PGconn*>(database_.pg_);
+
+    int fd = lo_open(pg, oid_, INV_WRITE);
+    if (fd < 0)
+    {
+      database_.ThrowException(true);
+    }
+
+    const char* position = reinterpret_cast<const char*>(data);
+    while (size > 0)
+    {
+      int chunk = (size > static_cast<size_t>(MAX_CHUNK_SIZE) ?
+                   MAX_CHUNK_SIZE : static_cast<int>(size));
+      int nbytes = lo_write(pg, fd, position, chunk);
+      if (nbytes <= 0)
+      {
+        lo_close(pg, fd);
+        database_.ThrowException(true);
+      }
+
+      size -= nbytes;
+      position += nbytes;
+    }
+
+    lo_close(pg, fd);
+  }
+
+
+  PostgreSQLLargeObject::PostgreSQLLargeObject(PostgreSQLDatabase& database,
+                                               const void* data,
+                                               size_t size) : 
+    database_(database)
+  {
+    Create();
+    Write(data, size);
+  }
+
+
+  PostgreSQLLargeObject::PostgreSQLLargeObject(PostgreSQLDatabase& database,
+                                               const std::string& s) : 
+    database_(database)
+  {
+    Create();
+
+    if (s.size() != 0)
+    {
+      Write(s.c_str(), s.size());
+    }
+    else
+    {
+      Write(NULL, 0);
+    }
+  }
+
+
+  class PostgreSQLLargeObject::Reader
+  {
+  private: 
+    PostgreSQLDatabase& database_;
+    int fd_;
+    size_t size_;
+
+  public:
+    Reader(PostgreSQLDatabase& database,
+           const std::string& oid) : 
+      database_(database)
+    {
+      PGconn* pg = reinterpret_cast<PGconn*>(database.pg_);
+      Oid id = boost::lexical_cast<Oid>(oid);
+
+      fd_ = lo_open(pg, id, INV_READ);
+
+      if (fd_ < 0 ||
+          lo_lseek(pg, fd_, 0, SEEK_END) < 0)
+      {
+        LOG(ERROR) << "PostgreSQL: No such large object in the database; "
+                   << "Make sure you use a transaction";
+        database.ThrowException(false);
+      }
+
+      // Get the size of the large object
+      int size = lo_tell(pg, fd_);
+      if (size < 0)
+      {
+        database.ThrowException(true);
+      }
+      size_ = static_cast<size_t>(size);
+
+      // Go to the first byte of the object
+      lo_lseek(pg, fd_, 0, SEEK_SET);
+    }
+
+    ~Reader()
+    {
+      lo_close(reinterpret_cast<PGconn*>(database_.pg_), fd_);
+    }
+
+    size_t GetSize() const
+    {
+      return size_;
+    }
+
+    void Read(char* target)
+    {
+      for (size_t position = 0; position < size_; )
+      {
+        size_t remaining = size_ - position;
+
+        int nbytes = lo_read(reinterpret_cast<PGconn*>(database_.pg_), fd_, target + position, remaining);
+        if (nbytes < 0)
+        {
+          LOG(ERROR) << "PostgreSQL: Unable to read the large object in the database";
+          database_.ThrowException(false);
+        }
+
+        position += static_cast<size_t>(nbytes);
+      }
+    }
+  };
+  
+
+  void PostgreSQLLargeObject::Read(std::string& target,
+                                   PostgreSQLDatabase& database,
+                                   const std::string& oid)
+  {
+    Reader reader(database, oid);
+    target.resize(reader.GetSize());    
+
+    if (target.size() > 0)
+    {
+      reader.Read(&target[0]);
+    }
+  }
+
+
+  void PostgreSQLLargeObject::Read(void*& target,
+                                   size_t& size,
+                                   PostgreSQLDatabase& database,
+                                   const std::string& oid)
+  {
+    Reader reader(database, oid);
+    size = reader.GetSize();
+
+    if (size == 0)
+    {
+      target = NULL;
+    }
+    else
+    {
+      target = malloc(size);
+      reader.Read(reinterpret_cast<char*>(target));
+    }
+  }
+
+
+  std::string PostgreSQLLargeObject::GetOid() const
+  {
+    return boost::lexical_cast<std::string>(oid_);
+  }
+
+
+  void PostgreSQLLargeObject::Delete(PostgreSQLDatabase& database,
+                                     const std::string& oid)
+  {
+    PGconn* pg = reinterpret_cast<PGconn*>(database.pg_);
+    Oid id = boost::lexical_cast<Oid>(oid);
+
+    if (lo_unlink(pg, id) < 0)
+    {
+      LOG(ERROR) << "PostgreSQL: Unable to delete the large object from the database";
+      database.ThrowException(false);
+    }
+  }
+}