#include <stdio.h>

#include <libelf.h>
#include <gelf.h>

#include <libelfu/libelfu.h>



void elfu_copySegments1(Elf *eo, Elf *ei)
{
  size_t i, n;

  if (elf_getphdrnum(ei, &n)) {
    fprintf(stderr, "elf_getphdrnum() failed: %s\n", elf_errmsg(-1));
  }

  if (!gelf_newphdr(eo, n)) {
    fprintf(stderr, "gelf_newphdr() failed: %s\n", elf_errmsg(-1));
  }

  for (i = 0; i < n; i++) {
    GElf_Phdr phdr, phdrOut;

    if (gelf_getphdr(ei, i, &phdr) != &phdr) {
      fprintf(stderr, "gelf_getphdr() failed for #%d: %s\n", i, elf_errmsg(-1));
      break;
    }

    if (gelf_getphdr(eo, i, &phdrOut) != &phdrOut) {
      fprintf(stderr, "gelf_getphdr() failed for #%d: %s\n", i, elf_errmsg(-1));
      break;
    }

    phdrOut.p_type = phdr.p_type;
    /* p_offset */
    phdrOut.p_vaddr = phdr.p_vaddr;
    phdrOut.p_paddr = phdr.p_paddr;
    /* p_filesz */
    /* p_memsz */
    phdrOut.p_flags = phdr.p_flags;
    phdrOut.p_align = phdr.p_align;

    if (!gelf_update_phdr (eo, i, &phdrOut)) {
      fprintf(stderr, "gelf_update_ehdr() failed: %s\n", elf_errmsg(-1));
    }
  }

  /* Tell libelf that phdrs have changed */
  elf_flagphdr(eo, ELF_C_SET, ELF_F_DIRTY);
}


void elfu_copySegments2(Elf *eo, Elf *ei)
{
  size_t i, n;

  if (elf_getphdrnum(ei, &n)) {
    fprintf(stderr, "elf_getphdrnum() failed: %s\n", elf_errmsg(-1));
  }

  for (i = 0; i < n; i++) {
    GElf_Phdr phdr, phdrOut;

    if (gelf_getphdr(ei, i, &phdr) != &phdr) {
      fprintf(stderr, "gelf_getphdr() failed for #%d: %s\n", i, elf_errmsg(-1));
      break;
    }

    if (gelf_getphdr(eo, i, &phdrOut) != &phdrOut) {
      fprintf(stderr, "gelf_getphdr() failed for #%d: %s\n", i, elf_errmsg(-1));
      break;
    }

    /* Start of segment */
    if (phdr.p_type == PT_PHDR) {
      /* Skip PHDR entries and fix them up later */
    }
    else if (phdr.p_offset == 0) {
      /* The text segment usually loads the whole ELF header */
      phdrOut.p_offset = 0;
    } else {
      /* Try to guess the start of the segment */
      Elf_Scn *scn, *scnOut;
      GElf_Shdr shdr, shdrOut;

      scn = elfu_firstSectionInSegment(ei, &phdr);
      if (!scn) {
        fprintf(stderr, "elfu_firstSectionInSegment() failed for segment #%d\n", i);
        continue;
      }

      if (gelf_getshdr(scn, &shdr) != &shdr) {
        fprintf(stderr, "gelf_getshdr() failed: %s\n", elf_errmsg(-1));
      }

      if (phdr.p_offset < shdr.sh_offset) {
        fprintf(stderr, "elfu_copySegments2: Segment #%d starts before first contained section.\n", i);
      }

      scnOut = elf_getscn(eo, elf_ndxscn(scn));
      if (!scnOut) {
        fprintf(stderr, "elf_getscn() failed: %s\n", elf_errmsg(-1));
      }

      if (gelf_getshdr(scnOut, &shdrOut) != &shdrOut) {
        fprintf(stderr, "gelf_getshdr() failed: %s\n", elf_errmsg(-1));
      }

      phdrOut.p_offset = shdrOut.sh_offset;
    }

    /* File length of segment */
    if (phdr.p_type == PT_PHDR) {
      /* Skip PHDR entries and fix them up later */
    }
    else if (phdr.p_memsz == 0) {
      phdrOut.p_filesz = 0;
      phdrOut.p_memsz = 0;
    } else {
      /* Try to guess the end of the segment */
      Elf_Scn *scn, *scnOut;
      GElf_Shdr shdr, shdrOut;

      scn = elfu_lastSectionInSegment(ei, &phdr);
      if (!scn) {
        fprintf(stderr, "elfu_lastSectionInSegment() failed for segment #%d\n", i);
        continue;
      }

      if (gelf_getshdr(scn, &shdr) != &shdr) {
        fprintf(stderr, "gelf_getshdr() failed: %s\n", elf_errmsg(-1));
      }

      if (phdr.p_offset + phdr.p_filesz > shdr.sh_offset + shdr.sh_size) {
        fprintf(stderr, "elfu_copySegments2: Segment #%d ends after last contained section.\n", i);
      }

      scnOut = elf_getscn(eo, elf_ndxscn(scn));
      if (!scnOut) {
        fprintf(stderr, "elf_getscn() failed: %s\n", elf_errmsg(-1));
      }

      if (gelf_getshdr(scnOut, &shdrOut) != &shdrOut) {
        fprintf(stderr, "gelf_getshdr() failed: %s\n", elf_errmsg(-1));
      }

      phdrOut.p_filesz = shdrOut.sh_offset - phdrOut.p_offset;
      if (shdrOut.sh_type != SHT_NOBITS) {
        phdrOut.p_filesz += shdrOut.sh_size;
      }

      phdrOut.p_memsz = shdrOut.sh_offset - phdrOut.p_offset + shdrOut.sh_size;
    }

    if (!gelf_update_phdr (eo, i, &phdrOut)) {
      fprintf(stderr, "gelf_update_ehdr() failed: %s\n", elf_errmsg(-1));
    }
  }

  /* Tell libelf that phdrs have changed */
  elf_flagphdr(eo, ELF_C_SET, ELF_F_DIRTY);
}