# HG changeset patch
# User Sebastien Jodogne <s.jodogne@gmail.com>
# Date 1458575248 -3600
# Node ID ff11ba08e5d0bbea03cdebf07a575ccca75f1762
# Parent  2d46e378960d20cd90e111a29856e6ca26378cd1
Toolbox::ReadHeader

diff -r 2d46e378960d -r ff11ba08e5d0 Core/Toolbox.cpp
--- a/Core/Toolbox.cpp	Mon Mar 21 15:21:23 2016 +0100
+++ b/Core/Toolbox.cpp	Mon Mar 21 16:47:28 2016 +0100
@@ -206,6 +206,17 @@
   }
 
 
+  static std::streamsize GetStreamSize(std::istream& f)
+  {
+    // http://www.cplusplus.com/reference/iostream/istream/tellg/
+    f.seekg(0, std::ios::end);
+    std::streamsize size = f.tellg();
+    f.seekg(0, std::ios::beg);
+
+    return size;
+  }
+
+
   void Toolbox::ReadFile(std::string& content,
                          const std::string& path) 
   {
@@ -222,11 +233,7 @@
       throw OrthancException(ErrorCode_InexistentFile);
     }
 
-    // http://www.cplusplus.com/reference/iostream/istream/tellg/
-    f.seekg(0, std::ios::end);
-    std::streamsize size = f.tellg();
-    f.seekg(0, std::ios::beg);
-
+    std::streamsize size = GetStreamSize(f);
     content.resize(size);
     if (size != 0)
     {
@@ -237,6 +244,51 @@
   }
 
 
+  bool Toolbox::ReadHeader(std::string& header,
+                           const std::string& path,
+                           size_t headerSize)
+  {
+    if (!IsRegularFile(path))
+    {
+      LOG(ERROR) << std::string("The path does not point to a regular file: ") << path;
+      throw OrthancException(ErrorCode_RegularFileExpected);
+    }
+
+    boost::filesystem::ifstream f;
+    f.open(path, std::ifstream::in | std::ifstream::binary);
+    if (!f.good())
+    {
+      throw OrthancException(ErrorCode_InexistentFile);
+    }
+
+    bool full = true;
+
+    {
+      std::streamsize size = GetStreamSize(f);
+      if (size <= 0)
+      {
+        headerSize = 0;
+        full = false;
+      }
+      else if (static_cast<size_t>(size) < headerSize)
+      {
+        headerSize = size;  // Truncate to the size of the file
+        full = false;
+      }
+    }
+
+    header.resize(headerSize);
+    if (headerSize != 0)
+    {
+      f.read(reinterpret_cast<char*>(&header[0]), headerSize);
+    }
+
+    f.close();
+
+    return full;
+  }
+
+
   void Toolbox::WriteFile(const void* content,
                           size_t size,
                           const std::string& path)
diff -r 2d46e378960d -r ff11ba08e5d0 Core/Toolbox.h
--- a/Core/Toolbox.h	Mon Mar 21 15:21:23 2016 +0100
+++ b/Core/Toolbox.h	Mon Mar 21 16:47:28 2016 +0100
@@ -66,6 +66,10 @@
     void ReadFile(std::string& content,
                   const std::string& path);
 
+    bool ReadHeader(std::string& header,
+                    const std::string& path,
+                    size_t headerSize);
+
     void WriteFile(const std::string& content,
                    const std::string& path);
 
diff -r 2d46e378960d -r ff11ba08e5d0 UnitTestsSources/UnitTestsMain.cpp
--- a/UnitTestsSources/UnitTestsMain.cpp	Mon Mar 21 15:21:23 2016 +0100
+++ b/UnitTestsSources/UnitTestsMain.cpp	Mon Mar 21 16:47:28 2016 +0100
@@ -558,6 +558,16 @@
     ASSERT_EQ(11u, t.size());
     ASSERT_EQ(0, t[5]);
     ASSERT_EQ(0, memcmp(s.c_str(), t.c_str(), s.size()));
+
+    std::string h;
+    ASSERT_EQ(true, Toolbox::ReadHeader(h, path.c_str(), 1));
+    ASSERT_EQ(1, h.size());
+    ASSERT_EQ('H', h[0]);
+    ASSERT_EQ(true, Toolbox::ReadHeader(h, path.c_str(), 0));
+    ASSERT_EQ(0, h.size());
+    ASSERT_EQ(false, Toolbox::ReadHeader(h, path.c_str(), 32));
+    ASSERT_EQ(11u, h.size());
+    ASSERT_EQ(0, memcmp(s.c_str(), h.c_str(), s.size()));
   }
 
   std::string u;