/* Test program for changing data in one section (but not others) with gaps.

   Copyright (C) 2017 Red Hat, Inc.

   This file is part of elfutils.

   This file is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   elfutils is distributed in the hope that it will be useful, but

   WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H

# include <config.h>

#endif

#include <errno.h>

#include <fcntl.h>

#include <inttypes.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include ELFUTILS_HEADER(elf)

#include <gelf.h>

/* Index of last string added.  Returned by add_string ().  */

static size_t stridx = 0;

/* Adds a string and returns the offset in the section.  */

static size_t

add_strtab_entry (Elf_Scn *strtab, const char *str)

{

  size_t lastidx = stridx;

  size_t size = strlen (str) + 1;

  Elf_Data *data = elf_newdata (strtab);

  if (data == NULL)

    {

      printf ("cannot create data SHSTRTAB section: %s\n", elf_errmsg (-1));

      exit (1);

    }

  data->d_buf = (char *) str; /* Discards const, but we will not change. */

  data->d_type = ELF_T_BYTE;

  data->d_size = size;

  data->d_align = 1;

  data->d_version = EV_CURRENT;

  stridx += size;

  printf ("add_string: '%s', stridx: %zd, lastidx: %zd\n",

	  str, stridx, lastidx);

  return lastidx;

}

static Elf_Scn *

create_strtab (Elf *elf)

{

  // Create strtab section.

  Elf_Scn *scn = elf_newscn (elf);

  if (scn == NULL)

    {

      printf ("cannot create strings section: %s\n", elf_errmsg (-1));

      exit (1);

    }

  // Add an empty string to the table as NUL entry for section zero.

  add_strtab_entry (scn, "");

  GElf_Shdr shdr_mem;

  GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);

  if (shdr == NULL)

    {

      printf ("cannot get header for new strtab section: %s\n",

	      elf_errmsg (-1));

      exit (1);

    }

  shdr->sh_type = SHT_STRTAB;

  shdr->sh_flags = 0;

  shdr->sh_addr = 0;

  shdr->sh_link = SHN_UNDEF;

  shdr->sh_info = SHN_UNDEF;

  shdr->sh_addralign = 1;

  shdr->sh_entsize = 0;

  shdr->sh_name = add_strtab_entry (scn, ".strtab");

  // We have to store the section strtab index in the ELF header.

  // So sections have actual names.

  GElf_Ehdr ehdr_mem;

  GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem);

  if (ehdr == NULL)

    {

      printf ("cannot get ELF header: %s\n", elf_errmsg (-1));

      exit (1);

    }

  int ndx = elf_ndxscn (scn);

  ehdr->e_shstrndx = ndx;

  if (gelf_update_ehdr (elf, ehdr) == 0)

    {

      printf ("cannot update ELF header: %s\n", elf_errmsg (-1));

      exit (1);

    }

  // Finished strtab section, update the header.

  if (gelf_update_shdr (scn, shdr) == 0)

    {

      printf ("cannot update STRTAB section header: %s\n", elf_errmsg (-1));

      exit (1);

    }

  return scn;

}

static char sec_data[] = { 1, 2, 3, 4, 5 };

static char new_data[] = { 5, 4, 3, 2, 1 };

static void

add_data_section (Elf *elf, Elf_Scn *strtab, const char *sname)

{

  printf ("Add data section %s\n", sname);

  Elf_Scn *scn = elf_newscn (elf);

  if (scn == NULL)

    {

      printf ("cannot create strings section: %s\n", elf_errmsg (-1));

      exit (1);

    }

  GElf_Shdr shdr_mem;

  GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);

  if (shdr == NULL)

    {

      printf ("cannot get header for new %s section: %s\n",

	      sname, elf_errmsg (-1));

      exit (1);

    }

  shdr->sh_type = SHT_PROGBITS;

  shdr->sh_flags = 0;

  shdr->sh_addr = 0;

  shdr->sh_link = SHN_UNDEF;

  shdr->sh_info = SHN_UNDEF;

  shdr->sh_addralign = 128;  // Large alignment to force gap between sections.

  shdr->sh_entsize = 1;

  shdr->sh_name = add_strtab_entry (strtab, sname);

  if (gelf_update_shdr (scn, shdr) == 0)

    {

      printf ("cannot update %s section header: %s\n", sname, elf_errmsg (-1));

      exit (1);

    }

  /* Add some data, but less than alignment. */

  Elf_Data *data = elf_newdata (scn);

  if (data == NULL)

    {

      printf ("cannot update %s section header: %s\n", sname, elf_errmsg (-1));

      exit (1);

    }

  data->d_buf = sec_data;

  data->d_size = 5;

}

static void

check_data (const char *sname, Elf_Data *data, char *buf)

{

  printf ("check data %s [", sname);

  for (int i = 0; i < 5; i++)

    printf ("%d%s", buf[i], i < 4 ? "," : "");

  printf ("]\n");

  if (data == NULL || data->d_buf == NULL)

    {

      printf ("No data in section %s\n", sname);

      exit (1);

    }

  if (data->d_size != 5 || memcmp (data->d_buf, buf, 5) != 0)

    {

      printf ("Wrong data in section %s [", sname);

      for (size_t i = 0; i < data->d_size; i++)

	printf ("%d%s", ((char *)data->d_buf)[i],

		i < data->d_size - 1 ? "," : "");

      printf ("]\n");

      exit(1);

    }

}

static void

check_elf (const char *fname, int class, int use_mmap)

{

  printf ("\nfname: %s\n", fname);

  stridx = 0; // Reset strtab strings index

  int fd = open (fname, O_RDWR | O_CREAT | O_TRUNC, 0666);

  if (fd == -1)

    {

      printf ("cannot open `%s': %s\n", fname, strerror (errno));

      exit (1);

    }

  Elf *elf = elf_begin (fd, use_mmap ? ELF_C_WRITE_MMAP : ELF_C_WRITE, NULL);

  if (elf == NULL)

    {

      printf ("cannot create ELF descriptor: %s\n", elf_errmsg (-1));

      exit (1);

    }

  // Create an ELF header.

  if (gelf_newehdr (elf, class) == 0)

    {

      printf ("cannot create ELF header: %s\n", elf_errmsg (-1));

      exit (1);

    }

  GElf_Ehdr ehdr_mem;

  GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem);

  if (ehdr == NULL)

    {

      printf ("cannot get ELF header: %s\n", elf_errmsg (-1));

      exit (1);

    }

  // Initialize header.

  ehdr->e_ident[EI_DATA] = class == ELFCLASS64 ? ELFDATA2LSB : ELFDATA2MSB;

  ehdr->e_ident[EI_OSABI] = ELFOSABI_GNU;

  ehdr->e_type = ET_NONE;

  ehdr->e_machine = EM_X86_64;

  ehdr->e_version = EV_CURRENT;

  if (gelf_update_ehdr (elf, ehdr) == 0)

    {

      printf ("cannot update ELF header: %s\n", elf_errmsg (-1));

      exit (1);

    }

  Elf_Scn *strtab = create_strtab (elf);

  add_data_section (elf, strtab, ".data1");

  add_data_section (elf, strtab, ".data2");

  add_data_section (elf, strtab, ".data3");

  add_data_section (elf, strtab, ".data4");

  // Write everything to disk.

  if (elf_update (elf, ELF_C_WRITE) < 0)

    {

      printf ("failure in elf_update(WRITE): %s\n", elf_errmsg (-1));

      exit (1);

    }

  if (elf_end (elf) != 0)

    {

      printf ("failure in elf_end: %s\n", elf_errmsg (-1));

      exit (1);

    }

  close (fd);

  /* Reread the ELF from disk now.  */

  printf ("Rereading %s\n", fname);

  fd = open (fname, O_RDWR, 0666);

  if (fd == -1)

    {

      printf ("cannot (re)open `%s': %s\n", fname, strerror (errno));

      exit (1);

    }

  elf = elf_begin (fd, use_mmap ? ELF_C_RDWR_MMAP : ELF_C_RDWR, NULL);

  if (elf == NULL)

    {

      printf ("cannot create ELF descriptor read-only: %s\n", elf_errmsg (-1));

      exit (1);

    }

  /* We are going to change some data (in-place), but want the layout

     to stay exactly the same. */

  elf_flagelf (elf, ELF_C_SET, ELF_F_LAYOUT);

  size_t shdrstrndx;

  if (elf_getshdrstrndx (elf, &shdrstrndx) != 0)

    {

      printf ("cannot get shdr str ndx\n");

      exit (1);

    }

  printf ("shdrstrndx: %zd\n", shdrstrndx);

  // Get third data section and change it.

  Elf_Scn *checkscn = NULL;

  Elf_Scn *scn = elf_nextscn (elf, NULL);

  while (scn != NULL)

    {

      GElf_Shdr shdr_mem;

      GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);

      if (shdr == NULL)

	{

	  printf ("cannot get header for section: %s\n", elf_errmsg (-1));

	  exit (1);

	}

      const char *sname = elf_strptr (elf, shdrstrndx, shdr->sh_name);

      if (sname != NULL && strcmp (".data3", sname) == 0)

	checkscn = scn;

      // Get all data, but don't really use it

      // (this triggered the original bug).

      Elf_Data *data = elf_getdata (scn, NULL);

      if (data != NULL && data->d_buf != NULL && data->d_size == 0)

	{

	  printf ("Bad data...n");

	  exit (1);

	}

      scn = elf_nextscn (elf, scn);

    }

  if (checkscn == NULL)

    {

      printf ("ELF file doesn't have a .data3 section\n");

      exit (1);

    }

  Elf_Data *data = elf_getdata (checkscn, NULL);

  check_data (".data3", data, sec_data);

  memcpy (data->d_buf, new_data, 5);

  elf_flagdata (data, ELF_C_SET, ELF_F_DIRTY);

  // Write everything to disk.

  if (elf_update (elf, ELF_C_WRITE) < 0)

    {

      printf ("failure in elf_update(WRITE): %s\n", elf_errmsg (-1));

      exit (1);

    }

  if (elf_end (elf) != 0)

    {

      printf ("failure in elf_end: %s\n", elf_errmsg (-1));

      exit (1);

    }

  close (fd);

  // And read it in one last time.

  printf ("Rereading %s again\n", fname);

  fd = open (fname, O_RDONLY, 0666);

  if (fd == -1)

    {

      printf ("cannot open `%s' read-only: %s\n", fname, strerror (errno));

      exit (1);

    }

  elf = elf_begin (fd, use_mmap ? ELF_C_READ_MMAP : ELF_C_READ, NULL);

  if (elf == NULL)

    {

      printf ("cannot create ELF descriptor read-only: %s\n", elf_errmsg (-1));

      exit (1);

    }

  // Get all .data sections and check them.

  Elf_Scn *scn1 = NULL;

  Elf_Scn *scn2 = NULL;

  Elf_Scn *scn3 = NULL;

  Elf_Scn *scn4 = NULL;

  scn = elf_nextscn (elf, NULL);

  while (scn != NULL)

    {

      GElf_Shdr shdr_mem;

      GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);

      if (shdr == NULL)

	{

	  printf ("cannot get header for section: %s\n", elf_errmsg (-1));

	  exit (1);

	}

      const char *sname = elf_strptr (elf, shdrstrndx, shdr->sh_name);

      if (sname != NULL && strcmp (".data1", sname) == 0)

	scn1 = scn;

      else if (sname != NULL && strcmp (".data2", sname) == 0)

	scn2 = scn;

      else if (sname != NULL && strcmp (".data3", sname) == 0)

	scn3 = scn;

      else if (sname != NULL && strcmp (".data4", sname) == 0)

	scn4 = scn;

      scn = elf_nextscn (elf, scn);

    }

  if (scn1 == NULL)

    {

      printf ("ELF file doesn't have a .data1 section\n");

      exit (1);

    }

  data = elf_getdata (scn1, NULL);

  check_data (".data1", data, sec_data);

  if (scn2 == NULL)

    {

      printf ("ELF file doesn't have a .data2 section\n");

      exit (1);

    }

  data = elf_getdata (scn2, NULL);

  check_data (".data2", data, sec_data);

  if (scn3 == NULL)

    {

      printf ("ELF file doesn't have a .data3 section\n");

      exit (1);

    }

  data = elf_getdata (scn3, NULL);

  check_data (".data3", data, new_data);

  if (scn4 == NULL)

    {

      printf ("ELF file doesn't have a .data4 section\n");

      exit (1);

    }

  data = elf_getdata (scn4, NULL);

  check_data (".data4", data, sec_data);

  if (elf_end (elf) != 0)

    {

      printf ("failure in elf_end: %s\n", elf_errmsg (-1));

      exit (1);

    }

  close (fd);

  unlink (fname);

}

int

main (int argc __attribute__ ((unused)),

      char *argv[] __attribute__ ((unused)))

{

  elf_version (EV_CURRENT);

  elf_fill (0xA);

  check_elf ("fill.elf.32", ELFCLASS32, 0);

  check_elf ("fill.elf.32.mmap", ELFCLASS32, 1);

  check_elf ("fill.elf.64", ELFCLASS64, 0);

  check_elf ("fill.elf.64.mmap", ELFCLASS64, 1);

  return 0;

}