/* Copyright (C) 2013 Free Software Foundation, Inc.

   This program 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.

   This program 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/>.  */

/* Version 2013-06-24.  */

#define _GNU_SOURCE

#include "system.h"

#include <string.h>

#include <fcntl.h>

#include <errno.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

#include <sys/mman.h>

#include <endian.h>

#include <stdio.h>

#include <stdlib.h>

#include <error.h>

#include <libelf.h>

#include <gelf.h>

#ifndef _

#define _(x) x

#endif

#define static_assert(expr) \

  extern int never_defined_just_used_for_checking[(expr) ? 1 : -1]

#ifndef min

# define min(a, b) ((a) < (b) ? (a) : (b))

#endif

static_assert (sizeof (unsigned long) >= sizeof (uint32_t));

typedef int bool;

static const bool false = 0, true = 1;

/* This is bfd_calc_gnu_debuglink_crc32 from bfd/opncls.c.  */

static unsigned long

    calc_gnu_debuglink_crc32 (unsigned long crc,

			      const unsigned char *buf,

			      size_t len)

{

  static const unsigned long crc32_table[256] =

    {

      0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,

      0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,

      0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,

      0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,

      0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,

      0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,

      0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,

      0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,

      0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,

      0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,

      0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,

      0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,

      0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,

      0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,

      0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,

      0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,

      0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,

      0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,

      0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,

      0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,

      0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,

      0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,

      0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,

      0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,

      0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,

      0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,

      0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,

      0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,

      0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,

      0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,

      0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,

      0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,

      0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,

      0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,

      0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,

      0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,

      0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,

      0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,

      0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,

      0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,

      0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,

      0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,

      0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,

      0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,

      0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,

      0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,

      0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,

      0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,

      0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,

      0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,

      0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,

      0x2d02ef8d

    };

  const unsigned char *end;

  crc = ~crc & 0xffffffff;

  for (end = buf + len; buf < end; ++ buf)

    crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);

  return ~crc & 0xffffffff;

}

static size_t updated_count, matched_count, failed_count;

static const char *usr_lib_debug;

static bool

crc32 (const char *fname, const char *base_fname, uint32_t *crcp)

{

  char *reldir = strdup (base_fname);

  if (reldir == NULL)

    error (1, 0, _("out of memory"));

  char *s = reldir + strlen (reldir);

  while (s > reldir && s[-1] != '/')

    *--s = '\0';

  char *debugname;

  if (asprintf (&debugname, "%s/%s/%s", usr_lib_debug, reldir, fname) <= 0)

    error (1, 0, _("out of memory"));

  free (reldir);

  int fd = open (debugname, O_RDONLY);

  if (fd == -1)

    {

      error (0, errno, _("cannot open \"%s\""), debugname);

      return false;

    }

  off64_t size = lseek64 (fd, 0, SEEK_END);

  if (size == -1)

    {

      error (0, errno, _("cannot get size of \"%s\""), debugname);

      return false;

    }

  off_t offset = 0;

  uint32_t crc = 0;

  void *buf = NULL;

  while (offset < size)

    {

      const size_t maplen = min (0x10000, size - offset);

      void *map = NULL;

      if (buf == NULL)

	{

	  map = mmap (NULL, maplen, PROT_READ, MAP_PRIVATE | MAP_POPULATE,

		      fd, offset);

	  if (map == MAP_FAILED)

	    {

	      error (0, errno, _("cannot map 0x%llx bytes at offset 0x%llx "

				 "of file \"%s\""),

		     (unsigned long long) maplen, (unsigned long long) offset,

		     debugname);

	      map = NULL;

	    }

	}

      if (map == NULL)

	{

	  if (buf == NULL)

	    {

	      buf = malloc (maplen);

	      if (buf == NULL)

		error (1, 0, _("out of memory"));

	    }

	  ssize_t got = pread (fd, buf, maplen, offset);

	  if (got != maplen)

	    {

	      error (0, errno, _("cannot read 0x%llx bytes at offset 0x%llx "

				 "of file \"%s\""),

		     (unsigned long long) maplen, (unsigned long long) offset,

		     debugname);

	      free (buf);

	      free (debugname);

	      return false;

	    }

	}

      crc = calc_gnu_debuglink_crc32 (crc, map ?: buf, maplen);

      if (map && munmap (map, maplen) != 0)

	error (1, errno, _("cannot unmap 0x%llx bytes at offset 0x%llx "

			   "of file \"%s\""),

	       (unsigned long long) maplen, (unsigned long long) offset,

	       debugname);

      offset += maplen;

    }

  free (buf);

  if (close (fd) != 0)

    {

      error (0, errno, _("cannot close \"%s\""), debugname);

      free (debugname);

      return false;

    }

  free (debugname);

  *crcp = crc;

  return true;

}

static bool

process (Elf *elf, int fd, const char *fname)

{

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

  if (ehdr == NULL)

    {

      error (0, 0, _("cannot get ELF header of \"%s\""), fname);

      return false;

    }

  if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB

      && ehdr->e_ident[EI_DATA] != ELFDATA2MSB)

    {

      error (0, 0, _("invalid ELF endianity of \"%s\""), fname);

      return false;

    }

  Elf_Scn *scn = NULL;

  const char scnname[] = ".gnu_debuglink";

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

    {

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

      if (shdr == NULL)

	{

	  error (0, 0, _("cannot get section # %zu in \"%s\""),

		 elf_ndxscn (scn), fname);

	  continue;

	}

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

      if (sname == NULL)

	{

	  error (0, 0, _("cannot get name of section # %zu in \"%s\""),

		 elf_ndxscn (scn), fname);

	  continue;

	}

      if (strcmp (sname, scnname) != 0)

	continue;

      Elf_Data *data = elf_getdata (scn, NULL);

      if (data == NULL)

	{

	  error (0, 0, _("cannot get data of section \"%s\" # %zu in \"%s\""),

		 scnname, elf_ndxscn (scn), fname);

	  continue;

	}

      if ((data->d_size & 3) != 0)

	{

	  error (0, 0, _("invalid size of section \"%s\" # %zu in \"%s\""),

		 scnname, elf_ndxscn (scn), fname);

	  continue;

	}

      const uint8_t *zerop = memchr (data->d_buf, '\0', data->d_size);

      const uint8_t *crcp = (zerop == NULL

			     ? NULL

			     : (const uint8_t *) ((uintptr_t) (zerop + 1 + 3)

						  & -4));

      if (crcp + 4 != (uint8_t *) data->d_buf + data->d_size)

	{

	  error (0, 0, _("invalid format of section \"%s\" # %zu in \"%s\""),

		 scnname, elf_ndxscn (scn), fname);

	  continue;

	}

      uint32_t had_crc_targetendian = *(const uint32_t *) crcp;

      uint32_t had_crc = (ehdr->e_ident[EI_DATA] == ELFDATA2LSB

			  ? le32toh (had_crc_targetendian)

			  : be32toh (had_crc_targetendian));

      uint32_t crc;

      if (! crc32 (data->d_buf, fname, &crc))

	return false;

      if (crc == had_crc)

	{

	  matched_count++;

	  return true;

	}

      updated_count++;

      off64_t seekto = (shdr->sh_offset + data->d_off

			+ (crcp - (const uint8_t *) data->d_buf));

      uint32_t crc_targetendian = (ehdr->e_ident[EI_DATA] == ELFDATA2LSB

				   ? htole32 (crc) : htobe32 (crc));

      ssize_t wrote = pwrite (fd, &crc_targetendian, sizeof (crc_targetendian),

			      seekto);

      if (wrote != sizeof (crc_targetendian))

	{

	  error (0, 0, _("cannot write new CRC to 0x%llx "

			 "inside section \"%s\" # %zu in \"%s\""),

		 (unsigned long long) seekto, scnname, elf_ndxscn (scn), fname);

	  return false;

	}

      return true;

    }

  error (0, 0, _("cannot find section \"%s\" in \"%s\""), scnname, fname);

  return false;

}

int

main (int argc, char **argv)

{

  if (argc < 2)

    error (1, 0, _("usr/lib/debug [<relative filenames>...]"));

  usr_lib_debug = argv[1];

  if (elf_version (EV_CURRENT) == EV_NONE)

    error (1, 0, _("error initializing libelf: %s"), elf_errmsg (-1));

  for (int argi = 2; argi < argc; argi++)

    {

      const char *fname = argv[argi];

      struct stat stat_buf;

      if (stat(fname, &stat_buf) < 0)

	{

	  error (0, errno, _("cannot stat input \"%s\""), fname);

	  failed_count++;

	  continue;

	}

      /* Make sure we can read and write */

      chmod (fname, stat_buf.st_mode | S_IRUSR | S_IWUSR);

      bool failed = false;

      int fd = open64 (fname, O_RDWR);

      if (fd == -1)

	{

	  error (0, errno, _("cannot open \"%s\""), fname);

	  failed = true;

	}

      else

	{

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

	  if (elf == NULL)

	    {

	      error (0, 0, _("cannot open \"%s\" as ELF: %s"), fname,

		     elf_errmsg (-1));

	      failed = true;

	    }

	  else

	    {

	      if (! process (elf, fd, fname))

		failed = true;

	      if (elf_end (elf) != 0)

		{

		  error (0, 0, _("cannot close \"%s\" as ELF: %s"), fname,

			 elf_errmsg (-1));

		  failed = true;

		}

	    }

	  if (close (fd) != 0)

	    {

	      error (0, errno, _("cannot close \"%s\""), fname);

	      failed = true;

	    }

	}

      /* Restore old access rights. Including any suid bits reset. */

      chmod (fname, stat_buf.st_mode);

      if (failed)

	failed_count++;

    }

  printf ("%s: Updated %zu CRC32s, %zu CRC32s did match.\n", argv[0],

	  updated_count, matched_count);

  if (failed_count)

    printf ("%s: Failed for %zu files.\n", argv[0], failed_count);

  return failed_count == 0 ? EXIT_SUCCESS : EXIT_FAILURE;

}