separated layout generation and saving

Many example elfs (hello_32, hello_64, asm ...) require that the
first section directly follows the program header table. The
section header is then placed between segments or at the end.

This change prepares the late placement of section header table.

elfio/elfio.hpp

@@ -158,9 +158,12 @@ class elfio
         fill_final_attributes();
         set_current_file_position();
 
+        is_still_good = layout_segments_and_their_sections();
+        is_still_good = is_still_good && layout_sections_without_segments();
+
         is_still_good = is_still_good && save_header( f );
-        is_still_good = is_still_good && save_segments_and_their_sections( f );
-        is_still_good = is_still_good && save_sections_without_segments( f );
+        is_still_good = is_still_good && save_sections( f );
+        is_still_good = is_still_good && save_segments( f );
 
         f.close();
 
@@ -440,6 +443,35 @@ class elfio
         return header->save( f );
     }
 
+//------------------------------------------------------------------------------
+    bool save_sections( std::ofstream& f )
+    {
+        for ( unsigned int i = 0; i < sections_.size(); ++i ) {
+            section *sec = sections_.at(i);
+
+            std::streampos headerPosition =
+                (std::streamoff)header->get_sections_offset() +
+                header->get_section_entry_size() * sec->get_index();
+
+            sec->save(f,headerPosition,sec->get_offset());
+        }
+        return true;
+    }
+
+//------------------------------------------------------------------------------
+    bool save_segments( std::ofstream& f )
+    {
+        for ( unsigned int i = 0; i < segments_.size(); ++i ) {
+            segment *seg = segments_.at(i);
+
+            std::streampos headerPosition = header->get_segments_offset()  +
+                header->get_segment_entry_size()*seg->get_index();
+
+            seg->save( f, headerPosition, seg->get_offset() );
+        }
+        return true;
+    }
+
 
 //------------------------------------------------------------------------------
     void set_current_file_position()
@@ -514,27 +546,24 @@ class elfio
 
 
 //------------------------------------------------------------------------------
-    bool save_sections_without_segments( std::ofstream& f )
+    bool layout_sections_without_segments( )
     {
         for ( unsigned int i = 0; i < sections_.size(); ++i ) {
             if ( is_section_without_segment( i ) ) {
-                Elf_Xword section_align = sections_[i]->get_addr_align();
+                section *sec = sections_[i];
+
+                Elf_Xword section_align = sec->get_addr_align();
                 if ( section_align > 1 && current_file_pos % section_align != 0 ) {
                     current_file_pos += section_align -
                                             current_file_pos % section_align;
                 }
 
-                std::streampos headerPosition =
-                    (std::streamoff)header->get_sections_offset() +
-                    header->get_section_entry_size() * sections_[i]->get_index();
-
-                sections_[i]->save( f,
-                                    headerPosition,
-                                    (std::streamoff)current_file_pos );
+                if ( 0 != sec->get_index() )
+                  sec->set_offset(current_file_pos);
 
-                if ( SHT_NOBITS != sections_[i]->get_type() &&
-                     SHT_NULL   != sections_[i]->get_type() ) {
-                    current_file_pos += sections_[i]->get_size();
+                if ( SHT_NOBITS != sec->get_type() &&
+                     SHT_NULL   != sec->get_type() ) {
+                    current_file_pos += sec->get_size();
                 }
             }
         }
@@ -544,7 +573,7 @@ class elfio
 
 
 //------------------------------------------------------------------------------
-    bool save_segments_and_their_sections( std::ofstream& f )
+    bool layout_segments_and_their_sections( )
     {
         std::vector<segment*>  worklist;
         std::vector<bool>      section_generated(sections.size(),false);
@@ -577,9 +606,6 @@ class elfio
                 Elf_Half index = seg->get_section_index_at( j );
 
                 section* sec = sections[ index ];
-                std::streampos headerPosition =
-                    (std::streamoff)header->get_sections_offset() +
-                    header->get_section_entry_size()*sec->get_index();
 
                 Elf_Xword secAlign = 0;
                 // fix up the alignment
@@ -620,19 +646,17 @@ class elfio
                     sec->set_address( seg->get_virtual_address()
                                       + current_file_pos - seg_start_pos);
 
-                sec->save( f, headerPosition, (std::streamoff)current_file_pos );
+                if ( 0 != sec->get_index() )
+                  sec->set_offset(current_file_pos);
+
                 if ( SHT_NOBITS != sec->get_type() && SHT_NULL != sec->get_type() )
                   current_file_pos += sec->get_size();
                 section_generated[index] = true;
             }
 
-            Elf64_Off segment_header_position = header->get_segments_offset()  +
-                header->get_segment_entry_size()*seg->get_index();
-
             seg->set_file_size( segment_filesize );
             seg->set_memory_size( segment_memory );
-            seg->save( f, (std::streamoff)segment_header_position,
-                (std::streamoff)seg_start_pos );
+            seg->set_offset(seg_start_pos);
         }
 
         return true;

elfio/elfio_section.hpp

@@ -53,7 +53,7 @@ class section
     virtual void        append_data( const std::string& data )          = 0;
 
   protected:
-    ELFIO_GET_ACCESS_DECL( Elf64_Off, offset );
+    ELFIO_GET_SET_ACCESS_DECL( Elf64_Off, offset );
     ELFIO_SET_ACCESS_DECL( Elf_Half,  index  );
     
     virtual void load( std::istream&  f,
@@ -196,7 +196,7 @@ class section_impl : public section
 //------------------------------------------------------------------------------
   protected:
 //------------------------------------------------------------------------------
-    ELFIO_GET_ACCESS( Elf64_Off, offset, header.sh_offset );
+    ELFIO_GET_SET_ACCESS( Elf64_Off, offset, header.sh_offset );
 
 //------------------------------------------------------------------------------
     void

elfio/elfio_segment.hpp

@@ -50,7 +50,7 @@ class segment
     virtual Elf_Half get_section_index_at( Elf_Half num )                const = 0;
 
   protected:
-    ELFIO_GET_ACCESS_DECL( Elf64_Off, offset );
+    ELFIO_GET_SET_ACCESS_DECL( Elf64_Off, offset );
     ELFIO_SET_ACCESS_DECL( Elf_Half,  index  );
     
     virtual const std::vector<Elf_Half>& get_sections() const               = 0;
@@ -136,7 +136,7 @@ class segment_impl : public segment
 //------------------------------------------------------------------------------
   protected:
 //------------------------------------------------------------------------------
-    ELFIO_GET_ACCESS( Elf64_Off, offset, ph.p_offset );
+    ELFIO_GET_SET_ACCESS( Elf64_Off, offset, ph.p_offset );
 
 //------------------------------------------------------------------------------
     const std::vector<Elf_Half>& get_sections() const