/* Copyright (C) 2015 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 <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <inttypes.h>

#include <libelf.h>

#include <gelf.h>

#include <stdbool.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

int

main (int argc, char *argv[])

{

  int result = 0;

  int cnt;

  if (argc < 3

      || (strcmp (argv[1], "elf") != 0

	  && strcmp (argv[1], "gnu") != 0))

    {

      printf ("Usage: (elf|gnu) files...\n");

      return -1;

    }

  int gnu;

  if (strcmp (argv[1], "gnu") == 0)

    gnu = 1;

  else

    gnu = 0;

  elf_version (EV_CURRENT);

  for (cnt = 2; cnt < argc; ++cnt)

    {

      int fd = open (argv[cnt], O_RDONLY);

      Elf *elf = elf_begin (fd, ELF_C_READ, NULL);

      if (elf == NULL)

	{

	  printf ("%s not usable %s\n", argv[cnt], elf_errmsg (-1));

	  result = 1;

	  close (fd);

	  continue;

	}

      /* To get the section names.  */

      size_t strndx;

      elf_getshdrstrndx (elf, &strndx);

      Elf_Scn *scn = NULL;

      while ((scn = elf_nextscn (elf, scn)) != NULL)

	{

	  size_t idx = elf_ndxscn (scn);

	  GElf_Shdr mem;

	  GElf_Shdr *shdr = gelf_getshdr (scn, &mem;;

	  const char *name = elf_strptr (elf, strndx, shdr->sh_name);

	  if (shdr->sh_type == SHT_NOBITS

	      || (shdr->sh_flags & SHF_ALLOC) != 0)

	    {

	      printf ("Cannot compress %zd %s\n", idx, name);

	    }

	  else if ((shdr->sh_flags & SHF_COMPRESSED) != 0

		   || strncmp (name, ".zdebug", strlen (".zdebug")) == 0)

	    {

	      printf ("Already compressed %zd %s\n", idx, name);

	    }

	  else

	    {

	      size_t orig_size = shdr->sh_size;

	      printf ("Lets compress %zd %s, size: %" PRId64 "\n",

		      idx, name, shdr->sh_size);

	      Elf_Data *d = elf_getdata (scn, NULL);

	      if (d == NULL)

		{

		  printf ("Couldn't get orig data for section %zd\n", idx);

		  return -1;

		}

	      /* Make a copy so we can compare after

		 compression/decompression.  */

	      if (d->d_size != orig_size)

		{

		  printf ("Unexpected data size for orig section %zd\n", idx);

		  return -1;

		}

	      char *orig_buf = NULL;

	      if (orig_size > 0)

		{

		  orig_buf = malloc (d->d_size);

		  if (orig_buf == NULL)

		    {

		      printf ("No memory to copy section %zd data\n", idx);

		      return -1;

		    }

		  memcpy (orig_buf, d->d_buf, orig_size);

		}

	      bool forced = false;

	      if (gnu)

		{

		  int res = elf_compress_gnu (scn, 1, 0);

		  if (res == 0)

		    {

		      forced = true;

		      res = elf_compress_gnu (scn, 1, ELF_CHF_FORCE);

		    }

		  if (res < 0)

		    {

		      printf ("elf_compress_gnu%sfailed for section %zd: %s\n",

			      forced ? " (forced) " : " ",

			      idx, elf_errmsg (-1));

		      return -1;

		    }

		}

	      else

		{

		  int res = elf_compress (scn, ELFCOMPRESS_ZLIB, 0);

		  if (res == 0)

		    {

		      forced = true;

		      res = elf_compress (scn, ELFCOMPRESS_ZLIB, ELF_CHF_FORCE);

		    }

		  if (res < 0)

		    {

		      printf ("elf_compress%sfailed for section %zd: %s\n",

			      forced ? " (forced) " : " ",

			      idx, elf_errmsg (-1));

		      return -1;

		    }

		}

	      GElf_Shdr newmem;

	      GElf_Shdr *newshdr = gelf_getshdr (scn, &newmem);

	      size_t new_size = newshdr->sh_size;

	      d = elf_getdata (scn, NULL);

	      // Don't check this, might depend on zlib implementation.

	      // fprintf (stderr, "  new_size: %zd\n", new_size);

	      if (d->d_size != new_size)

		{

		  printf ("Unexpected data size for compressed section %zd\n",

			  idx);

		  return -1;

		}

	      if (forced && new_size < orig_size)

		{

		  printf ("section %zd forced to compress, but size smaller\n",

			  idx);

		  return -1;

		}

	      if (! forced && new_size >= orig_size)

		{

		  printf ("section %zd compressed to bigger size\n",

			  idx);

		  return -1;

		}

	      if (new_size == orig_size

		  && (orig_buf == NULL

		      || memcmp (orig_buf, d->d_buf, orig_size) == 0))

		{

		  printf ("section %zd didn't compress\n", idx);

		  return -1;

		}

	      if (gnu)

		{

		  if (elf_compress_gnu (scn, 0, 0) < 0)

		    {

		      printf ("elf_[un]compress_gnu failed for section %zd: %s\n",

			      idx, elf_errmsg (-1));

		      return -1;

		    }

		}

	      else

		{

		  if (elf_compress (scn, 0, 0) < 0)

		    {

		      printf ("elf_[un]compress failed for section %zd: %s\n",

			      idx, elf_errmsg (-1));

		      return -1;

		    }

		}

	      GElf_Shdr newermem;

	      GElf_Shdr *newershdr = gelf_getshdr (scn, &newermem);

	      size_t newer_size = newershdr->sh_size;

	      d = elf_getdata (scn, NULL);

	      // fprintf (stderr, "  newer_size: %zd\n", newer_size);

	      if (d->d_size != newer_size)

		{

		  printf ("Unexpected data size for compressed section %zd\n",

			  idx);

		  return -1;

		}

	      if (newer_size != orig_size

		  && (orig_buf == NULL

		      || memcmp (orig_buf, d->d_buf, orig_size) != 0))

		{

		  printf ("section %zd didn't correctly uncompress\n", idx);

		  return -1;

		}

	      free (orig_buf);

	      // Recompress the string table, just to make sure

	      // everything keeps working. See elf_strptr above.

	      if (! gnu && idx == strndx

		  && elf_compress (scn, ELFCOMPRESS_ZLIB, 0) < 0)

		{

		  printf ("couldn't recompress section header strings: %s\n",

			  elf_errmsg (-1));

		  return -1;

		}

	    }

	}

      elf_end (elf);

      close (fd);

    }

  return result;

}