#define _GNU_SOURCE
#include <link.h>
#include <stdio.h>

int callback (struct dl_phdr_info *info, size_t size, void *data) {
  printf ("\nname: %s\n", info->dlpi_name);

  ElfW(Phdr) *phdr = (ElfW(Phdr) *) info->dlpi_phdr;
  for (ElfW(Half) i = 0; i < info->dlpi_phnum; i++) {
    if (phdr->p_type == PT_NOTE) {
      ElfW(Addr) addr = info->dlpi_addr + info->dlpi_phdr[i].p_vaddr;
      ElfW(Addr) nend = addr + info->dlpi_phdr[i].p_memsz;
      //printf ("found NOTE segment at: %p to %p\n", addr, nend);

      while (addr < nend) {
	ElfW(Nhdr) *nhdr = (ElfW(Nhdr) *) addr;
	// According to the ELF spec, namesz and descsz do not include padding
	// but that's how they're laid out in memory; add the padding here.
	ElfW(Addr) nameoff = (((nhdr->n_namesz-1)>>2)+1)<<2;
	ElfW(Addr) descoff = (((nhdr->n_descsz-1)>>2)+1)<<2;

	if (nhdr->n_type == NT_GNU_BUILD_ID) {
	  const uint8_t *buf = (const uint8_t *) ((ElfW(Addr))(nhdr + 1) + nameoff);
	  printf("Build ID");
	  for (int j = 0; j < nhdr->n_descsz; j++)
	    printf(":%02X", buf[j]);
	  printf("\n");
	}

	//printf("skipping section type %02X\n", nhdr->n_type);
	addr = (ElfW(Addr))(nhdr + 1) + nameoff + descoff;
      }
    }

    phdr += 1;
  }

  return 0;
}

int main() {
  dl_iterate_phdr(callback, NULL);
}