Exercise #7

Complete the dl.c and elf.c programs.

dl.c

• It should use dlopen(3) and dlsym(3) to open the /lib64/libm.so.6 library and get the addresses for the sin() and cos() functions and compute and print the result of sin(cos(M_PI)) where M_PI is the constant:

#define M_PI 3.14159265358979323846 /* pi */

Your completed program should not in any way be linked against the math library, but should be equivalent to:

#include <stdio.h>
#include <math.h>

int main(void)
{
  printf("sin(cos(pi)) = %lf\n", sin(cos(M_PI)));
  return 0;
}

elf.c

• This program should print the header information for an ELF object ala: 'readelf -h <file>'. To do this it should mmap the ELF file into the processes address space (i.e. the mapfile() function) and then the map the Elf64_Ehdr structure onto it and print out the information in the same format as the readelf program outputs.