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Use constants for segment locations

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Serge Lamikhov-Center 2021-03-29 09:38:28 +03:00
parent 7409369fc0
commit 06097d962c
1 changed files with 30 additions and 8 deletions
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38
examples/writer/writer.cpp
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@ -20,10 +20,28 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
/*
* This example shows how to create ELF object file for Linux on x86
*
* Instructions:
* 1. Compile and link this file with ELFIO library
* g++ writer.cpp -o writer
* 2. Execute result file write_obj
* ./writer
* 3. Add executable flag to the output file
* chmod +x hello_x86_64
* 4. Run the result file:
* ./hello_x86_64
*/
#include <elfio/elfio.hpp>
using namespace ELFIO;
const Elf64_Addr CODE_ADDR = 0x00401000;
const Elf_Xword PAGE_SIZE = 0x1000;
const Elf64_Addr DATA_ADDR = CODE_ADDR + PAGE_SIZE;
int main( void )
{
elfio writer;
@ -45,21 +63,24 @@ int main( void )
char text[] = {
'\xB8', '\x04', '\x00', '\x00', '\x00', // mov eax, 4
'\xBB', '\x01', '\x00', '\x00', '\x00', // mov ebx, 1
'\xB9', '\x00', '\x20', '\x40', '\x00', // mov ecx, msg
'\xB9', '\x00', '\x00', '\x00', '\x00', // mov ecx, msg
'\xBA', '\x0E', '\x00', '\x00', '\x00', // mov edx, 14
'\xCD', '\x80', // int 0x80
'\xB8', '\x01', '\x00', '\x00', '\x00', // mov eax, 1
'\xCD', '\x80' // int 0x80
};
// Adjust data address for 'msg'
*(uint32_t*)( text + 11 ) = DATA_ADDR;
text_sec->set_data( text, sizeof( text ) );
// Create a loadable segment
segment* text_seg = writer.segments.add();
text_seg->set_type( PT_LOAD );
text_seg->set_virtual_address( 0x00401000 );
text_seg->set_physical_address( 0x00401000 );
text_seg->set_virtual_address( CODE_ADDR );
text_seg->set_physical_address( CODE_ADDR );
text_seg->set_flags( PF_X | PF_R );
text_seg->set_align( 0x1000 );
text_seg->set_align( PAGE_SIZE );
// Add code section into program segment
text_seg->add_section_index( text_sec->get_index(),
@ -80,10 +101,10 @@ int main( void )
// Create a read/write segment
segment* data_seg = writer.segments.add();
data_seg->set_type( PT_LOAD );
data_seg->set_virtual_address( 0x00402000 );
data_seg->set_physical_address( 0x00402000 );
data_seg->set_virtual_address( DATA_ADDR );
data_seg->set_physical_address( DATA_ADDR );
data_seg->set_flags( PF_W | PF_R );
data_seg->set_align( 0x1000 );
data_seg->set_align( PAGE_SIZE );
// Add code section into program segment
data_seg->add_section_index( data_sec->get_index(),
@ -93,6 +114,7 @@ int main( void )
section* note_sec = writer.sections.add( ".note" );
note_sec->set_type( SHT_NOTE );
note_sec->set_addr_align( 1 );
note_section_accessor note_writer( writer, note_sec );
note_writer.add_note( 0x01, "Created by ELFIO", 0, 0 );
char descr[6] = { 0x31, 0x32, 0x33, 0x34, 0x35, 0x36 };
@ -103,7 +125,7 @@ int main( void )
// In this example, the code starts at the first address of the
// 'text_seg' segment. Therefore, the start address is set
// to be equal to the segment location
writer.set_entry( 0x00401000 );
writer.set_entry( CODE_ADDR );
// Create ELF file
writer.save( "hello_x86_64" );