/* Compressed section support (intended for debug sections).

   Copyright (C) 2008-2024 Free Software Foundation, Inc.

   This file is part of BFD, the Binary File Descriptor library.

   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, write to the Free Software

   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,

   MA 02110-1301, USA.  */

#include "sysdep.h"

#include <zlib.h>

#ifdef HAVE_ZSTD

#include <zstd.h>

#endif

#include "bfd.h"

#include "elf-bfd.h"

#include "libbfd.h"

#include "safe-ctype.h"

#include "libiberty.h"

#define MAX_COMPRESSION_HEADER_SIZE 24

/*

EXTERNAL

.{* Types of compressed DWARF debug sections.  *}

.enum compressed_debug_section_type

.{

.  COMPRESS_DEBUG_NONE = 0,

.  COMPRESS_DEBUG_GNU_ZLIB = 1 << 1,

.  COMPRESS_DEBUG_GABI_ZLIB = 1 << 2,

.  COMPRESS_DEBUG_ZSTD = 1 << 3,

.  COMPRESS_UNKNOWN = 1 << 4

.};

.

.{* Tuple for compressed_debug_section_type and their name.  *}

.struct compressed_type_tuple

.{

.  enum compressed_debug_section_type type;

.  const char *name;

.};

.

.{* Compression header ch_type values.  *}

.enum compression_type

.{

.  ch_none = 0,

.  ch_compress_zlib = 1 , {* Compressed with zlib.  *}

.  ch_compress_zstd = 2   {* Compressed with zstd (www.zstandard.org).  *}

.};

.

.static inline char *

.bfd_debug_name_to_zdebug (bfd *abfd, const char *name)

.{

.  size_t len = strlen (name);

.  char *new_name = (char *) bfd_alloc (abfd, len + 2);

.  if (new_name == NULL)

.    return NULL;

.  new_name[0] = '.';

.  new_name[1] = 'z';

.  memcpy (new_name + 2, name + 1, len);

.  return new_name;

.}

.

.static inline char *

.bfd_zdebug_name_to_debug (bfd *abfd, const char *name)

.{

.  size_t len = strlen (name);

.  char *new_name = (char *) bfd_alloc (abfd, len);

.  if (new_name == NULL)

.    return NULL;

.  new_name[0] = '.';

.  memcpy (new_name + 1, name + 2, len - 1);

.  return new_name;

.}

.

*/

/* Display texts for type of compressed DWARF debug sections.  */

static const struct compressed_type_tuple compressed_debug_section_names[] =

{

  { COMPRESS_DEBUG_NONE, "none" },

  { COMPRESS_DEBUG_GABI_ZLIB, "zlib" },

  { COMPRESS_DEBUG_GNU_ZLIB, "zlib-gnu" },

  { COMPRESS_DEBUG_GABI_ZLIB, "zlib-gabi" },

  { COMPRESS_DEBUG_ZSTD, "zstd" },

};

/*

FUNCTION

  bfd_get_compression_algorithm

SYNOPSIS

  enum compressed_debug_section_type

    bfd_get_compression_algorithm (const char *name);

DESCRIPTION

  Return compressed_debug_section_type from a string representation.

*/

enum compressed_debug_section_type

bfd_get_compression_algorithm (const char *name)

{

  for (unsigned i = 0; i < ARRAY_SIZE (compressed_debug_section_names); ++i)

    if (strcasecmp (compressed_debug_section_names[i].name, name) == 0)

      return compressed_debug_section_names[i].type;

  return COMPRESS_UNKNOWN;

}

/*

FUNCTION

  bfd_get_compression_algorithm_name

SYNOPSIS

  const char *bfd_get_compression_algorithm_name

    (enum compressed_debug_section_type type);

DESCRIPTION

  Return compression algorithm name based on the type.

*/

const char *

bfd_get_compression_algorithm_name (enum compressed_debug_section_type type)

{

  for (unsigned i = 0; i < ARRAY_SIZE (compressed_debug_section_names); ++i)

    if (type == compressed_debug_section_names[i].type)

      return compressed_debug_section_names[i].name;

  return NULL;

}

/*

FUNCTION

  bfd_update_compression_header

SYNOPSIS

  void bfd_update_compression_header

    (bfd *abfd, bfd_byte *contents, asection *sec);

DESCRIPTION

  Set the compression header at CONTENTS of SEC in ABFD and update

  elf_section_flags for compression.

*/

void

bfd_update_compression_header (bfd *abfd, bfd_byte *contents,

             asection *sec)

{

  if ((abfd->flags & BFD_COMPRESS) == 0)

    abort ();

  switch (bfd_get_flavour (abfd))

    {

    case bfd_target_elf_flavour:

      if ((abfd->flags & BFD_COMPRESS_GABI) != 0)

  {

    const struct elf_backend_data *bed = get_elf_backend_data (abfd);

    struct bfd_elf_section_data * esd = elf_section_data (sec);

    enum compression_type ch_type = (abfd->flags & BFD_COMPRESS_ZSTD

             ? ch_compress_zstd

             : ch_compress_zlib);

    /* Set the SHF_COMPRESSED bit.  */

    elf_section_flags (sec) |= SHF_COMPRESSED;

    if (bed->s->elfclass == ELFCLASS32)

      {

        Elf32_External_Chdr *echdr = (Elf32_External_Chdr *) contents;

        bfd_put_32 (abfd, ch_type, &echdr->ch_type);

        bfd_put_32 (abfd, sec->size, &echdr->ch_size);

        bfd_put_32 (abfd, 1u << sec->alignment_power,

        &echdr->ch_addralign);

        /* bfd_log2 (alignof (Elf32_Chdr)) */

        bfd_set_section_alignment (sec, 2);

        esd->this_hdr.sh_addralign = 4;

      }

    else

      {

        Elf64_External_Chdr *echdr = (Elf64_External_Chdr *) contents;

        bfd_put_32 (abfd, ch_type, &echdr->ch_type);

        bfd_put_32 (abfd, 0, &echdr->ch_reserved);

        bfd_put_64 (abfd, sec->size, &echdr->ch_size);

        bfd_put_64 (abfd, UINT64_C (1) << sec->alignment_power,

        &echdr->ch_addralign);

        /* bfd_log2 (alignof (Elf64_Chdr)) */

        bfd_set_section_alignment (sec, 3);

        esd->this_hdr.sh_addralign = 8;

      }

    break;

  }

      /* Clear the SHF_COMPRESSED bit.  */

      elf_section_flags (sec) &= ~SHF_COMPRESSED;

      /* Fall through.  */

    default:

      /* Write the zlib header.  It should be "ZLIB" followed by

   the uncompressed section size, 8 bytes in big-endian

   order.  */

      memcpy (contents, "ZLIB", 4);

      bfd_putb64 (sec->size, contents + 4);

      /* No way to keep the original alignment, just use 1 always. */

      bfd_set_section_alignment (sec, 0);

      break;

    }

}

/* Check the compression header at CONTENTS of SEC in ABFD and store the

   ch_type in CH_TYPE, uncompressed size in UNCOMPRESSED_SIZE, and the

   uncompressed data alignment in UNCOMPRESSED_ALIGNMENT_POWER if the

   compression header is valid.  */

static bool

bfd_check_compression_header (bfd *abfd, bfd_byte *contents,

            asection *sec,

            enum compression_type *ch_type,

            bfd_size_type *uncompressed_size,

            unsigned int *uncompressed_alignment_power)

{

  if (bfd_get_flavour (abfd) == bfd_target_elf_flavour

      && (elf_section_flags (sec) & SHF_COMPRESSED) != 0)

    {

      Elf_Internal_Chdr chdr;

      const struct elf_backend_data *bed = get_elf_backend_data (abfd);

      if (bed->s->elfclass == ELFCLASS32)

  {

    Elf32_External_Chdr *echdr = (Elf32_External_Chdr *) contents;

    chdr.ch_type = bfd_get_32 (abfd, &echdr->ch_type);

    chdr.ch_size = bfd_get_32 (abfd, &echdr->ch_size);

    chdr.ch_addralign = bfd_get_32 (abfd, &echdr->ch_addralign);

  }

      else

  {

    Elf64_External_Chdr *echdr = (Elf64_External_Chdr *) contents;

    chdr.ch_type = bfd_get_32 (abfd, &echdr->ch_type);

    chdr.ch_size = bfd_get_64 (abfd, &echdr->ch_size);

    chdr.ch_addralign = bfd_get_64 (abfd, &echdr->ch_addralign);

  }

      *ch_type = chdr.ch_type;

      if ((chdr.ch_type == ch_compress_zlib

     || chdr.ch_type == ch_compress_zstd)

    && chdr.ch_addralign == (chdr.ch_addralign & -chdr.ch_addralign))

  {

    *uncompressed_size = chdr.ch_size;

    *uncompressed_alignment_power = bfd_log2 (chdr.ch_addralign);

    return true;

  }

    }

  return false;

}

/*

FUNCTION

  bfd_get_compression_header_size

SYNOPSIS

  int bfd_get_compression_header_size (bfd *abfd, asection *sec);

DESCRIPTION

  Return the size of the compression header of SEC in ABFD.

*/

int

bfd_get_compression_header_size (bfd *abfd, asection *sec)

{

  if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)

    {

      if (sec == NULL)

  {

    if (!(abfd->flags & BFD_COMPRESS_GABI))

      return 0;

  }

      else if (!(elf_section_flags (sec) & SHF_COMPRESSED))

  return 0;

      if (get_elf_backend_data (abfd)->s->elfclass == ELFCLASS32)

  return sizeof (Elf32_External_Chdr);

      else

  return sizeof (Elf64_External_Chdr);

    }

  return 0;

}

/*

FUNCTION

  bfd_convert_section_setup

SYNOPSIS

  bool bfd_convert_section_setup

    (bfd *ibfd, asection *isec, bfd *obfd,

     const char **new_name, bfd_size_type *new_size);

DESCRIPTION

  Do early setup for objcopy, when copying @var{isec} in input

  BFD @var{ibfd} to output BFD @var{obfd}.  Returns the name and

  size of the output section.

*/

bool

bfd_convert_section_setup (bfd *ibfd, asection *isec, bfd *obfd,

         const char **new_name, bfd_size_type *new_size)

{

  bfd_size_type hdr_size;

  if ((isec->flags & SEC_DEBUGGING) != 0

      && (isec->flags & SEC_HAS_CONTENTS) != 0)

    {

      const char *name = *new_name;

      if ((obfd->flags & (BFD_DECOMPRESS | BFD_COMPRESS_GABI)) != 0)

  {

    /* When we decompress or compress with SHF_COMPRESSED,

       convert section name from .zdebug_* to .debug_*.  */

    if (startswith (name, ".zdebug_"))

      {

        name = bfd_zdebug_name_to_debug (obfd, name);

        if (name == NULL)

    return false;

      }

  }

      /* PR binutils/18087: Compression does not always make a

   section smaller.  So only rename the section when

   compression has actually taken place.  If input section

   name is .zdebug_*, we should never compress it again.  */

      else if (isec->compress_status == COMPRESS_SECTION_DONE

         && startswith (name, ".debug_"))

  {

    name = bfd_debug_name_to_zdebug (obfd, name);

    if (name == NULL)

      return false;

  }

      *new_name = name;

    }

  *new_size = bfd_section_size (isec);

  /* Do nothing if either input or output aren't ELF.  */

  if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour

      || bfd_get_flavour (obfd) != bfd_target_elf_flavour)

    return true;

  /* Do nothing if ELF classes of input and output are the same. */

  if (get_elf_backend_data (ibfd)->s->elfclass

      == get_elf_backend_data (obfd)->s->elfclass)

    return true;

  /* Convert GNU property size.  */

  if (startswith (isec->name, NOTE_GNU_PROPERTY_SECTION_NAME))

    {

      *new_size = _bfd_elf_convert_gnu_property_size (ibfd, obfd);

      return true;

    }

  /* Do nothing if input file will be decompressed.  */

  if ((ibfd->flags & BFD_DECOMPRESS))

    return true;

  /* Do nothing if the input section isn't a SHF_COMPRESSED section. */

  hdr_size = bfd_get_compression_header_size (ibfd, isec);

  if (hdr_size == 0)

    return true;

  /* Adjust the size of the output SHF_COMPRESSED section.  */

  if (hdr_size == sizeof (Elf32_External_Chdr))

    *new_size += sizeof (Elf64_External_Chdr) - sizeof (Elf32_External_Chdr);

  else

    *new_size -= sizeof (Elf64_External_Chdr) - sizeof (Elf32_External_Chdr);

  return true;

}

/*

FUNCTION

  bfd_convert_section_contents

SYNOPSIS

  bool bfd_convert_section_contents

    (bfd *ibfd, asection *isec, bfd *obfd,

     bfd_byte **ptr, bfd_size_type *ptr_size);

DESCRIPTION

  Convert the contents, stored in @var{*ptr}, of the section

  @var{isec} in input BFD @var{ibfd} to output BFD @var{obfd}

  if needed.  The original buffer pointed to by @var{*ptr} may

  be freed and @var{*ptr} is returned with memory malloc'd by this

  function, and the new size written to @var{ptr_size}.

*/

bool

bfd_convert_section_contents (bfd *ibfd, sec_ptr isec, bfd *obfd,

            bfd_byte **ptr, bfd_size_type *ptr_size)

{

  bfd_byte *contents;

  bfd_size_type ihdr_size, ohdr_size, size;

  Elf_Internal_Chdr chdr;

  bool use_memmove;

  /* Do nothing if either input or output aren't ELF.  */

  if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour

      || bfd_get_flavour (obfd) != bfd_target_elf_flavour)

    return true;

  /* Do nothing if ELF classes of input and output are the same.  */

  if (get_elf_backend_data (ibfd)->s->elfclass

      == get_elf_backend_data (obfd)->s->elfclass)

    return true;

  /* Convert GNU properties.  */

  if (startswith (isec->name, NOTE_GNU_PROPERTY_SECTION_NAME))

    return _bfd_elf_convert_gnu_properties (ibfd, isec, obfd, ptr,

              ptr_size);

  /* Do nothing if input file will be decompressed.  */

  if ((ibfd->flags & BFD_DECOMPRESS))

    return true;

  /* Do nothing if the input section isn't a SHF_COMPRESSED section.  */

  ihdr_size = bfd_get_compression_header_size (ibfd, isec);

  if (ihdr_size == 0)

    return true;

  /* PR 25221.  Check for corrupt input sections.  */

  if (ihdr_size > bfd_get_section_limit (ibfd, isec))

    /* FIXME: Issue a warning about a corrupt

       compression header size field ?  */

    return false;

  contents = *ptr;

  /* Convert the contents of the input SHF_COMPRESSED section to

     output.  Get the input compression header and the size of the

     output compression header.  */

  if (ihdr_size == sizeof (Elf32_External_Chdr))

    {

      Elf32_External_Chdr *echdr = (Elf32_External_Chdr *) contents;

      chdr.ch_type = bfd_get_32 (ibfd, &echdr->ch_type);

      chdr.ch_size = bfd_get_32 (ibfd, &echdr->ch_size);

      chdr.ch_addralign = bfd_get_32 (ibfd, &echdr->ch_addralign);

      ohdr_size = sizeof (Elf64_External_Chdr);

      use_memmove = false;

    }

  else if (ihdr_size != sizeof (Elf64_External_Chdr))

    {

      /* FIXME: Issue a warning about a corrupt

   compression header size field ?  */

      return false;

    }

  else

    {

      Elf64_External_Chdr *echdr = (Elf64_External_Chdr *) contents;

      chdr.ch_type = bfd_get_32 (ibfd, &echdr->ch_type);

      chdr.ch_size = bfd_get_64 (ibfd, &echdr->ch_size);

      chdr.ch_addralign = bfd_get_64 (ibfd, &echdr->ch_addralign);

      ohdr_size = sizeof (Elf32_External_Chdr);

      use_memmove = true;

    }

  size = bfd_section_size (isec) - ihdr_size + ohdr_size;

  if (!use_memmove)

    {

      contents = (bfd_byte *) bfd_malloc (size);

      if (contents == NULL)

  return false;

    }

  /* Write out the output compression header.  */

  if (ohdr_size == sizeof (Elf32_External_Chdr))

    {

      Elf32_External_Chdr *echdr = (Elf32_External_Chdr *) contents;

      bfd_put_32 (obfd, chdr.ch_type, &echdr->ch_type);

      bfd_put_32 (obfd, chdr.ch_size, &echdr->ch_size);

      bfd_put_32 (obfd, chdr.ch_addralign, &echdr->ch_addralign);

    }

  else

    {

      Elf64_External_Chdr *echdr = (Elf64_External_Chdr *) contents;

      bfd_put_32 (obfd, chdr.ch_type, &echdr->ch_type);

      bfd_put_32 (obfd, 0, &echdr->ch_reserved);

      bfd_put_64 (obfd, chdr.ch_size, &echdr->ch_size);

      bfd_put_64 (obfd, chdr.ch_addralign, &echdr->ch_addralign);

    }

  /* Copy the compressed contents.  */

  if (use_memmove)

    memmove (contents + ohdr_size, *ptr + ihdr_size, size - ohdr_size);

  else

    {

      memcpy (contents + ohdr_size, *ptr + ihdr_size, size - ohdr_size);

      free (*ptr);

      *ptr = contents;

    }

  *ptr_size = size;

  return true;

}

static bool

decompress_contents (bool is_zstd, bfd_byte *compressed_buffer,

         bfd_size_type compressed_size,

         bfd_byte *uncompressed_buffer,

         bfd_size_type uncompressed_size)

{

  if (is_zstd)

    {

#ifdef HAVE_ZSTD

      size_t ret = ZSTD_decompress (uncompressed_buffer, uncompressed_size,

            compressed_buffer, compressed_size);

      return !ZSTD_isError (ret);

#endif

    }

  z_stream strm;

  int rc;

  /* It is possible the section consists of several compressed

     buffers concatenated together, so we uncompress in a loop.  */

  /* PR 18313: The state field in the z_stream structure is supposed

     to be invisible to the user (ie us), but some compilers will

     still complain about it being used without initialisation.  So

     we first zero the entire z_stream structure and then set the fields

     that we need.  */

  memset (& strm, 0, sizeof strm);

  strm.avail_in = compressed_size;

  strm.next_in = (Bytef*) compressed_buffer;

  strm.avail_out = uncompressed_size;

  /* FIXME: strm.avail_in and strm.avail_out are typically unsigned

     int.  Supporting sizes that don't fit in an unsigned int is

     possible but will require some rewriting of this function.  */

  if (strm.avail_in != compressed_size || strm.avail_out != uncompressed_size)

    return false;

  BFD_ASSERT (Z_OK == 0);

  rc = inflateInit (&strm);

  while (strm.avail_in > 0 && strm.avail_out > 0)

    {

      if (rc != Z_OK)

  break;

      strm.next_out = ((Bytef*) uncompressed_buffer

           + (uncompressed_size - strm.avail_out));

      rc = inflate (&strm, Z_FINISH);

      if (rc != Z_STREAM_END)

  break;

      rc = inflateReset (&strm);

    }

  return inflateEnd (&strm) == Z_OK && rc == Z_OK && strm.avail_out == 0;

}

/* Compress section contents using zlib/zstd and store

   as the contents field.  This function assumes the contents

   field was allocated using bfd_malloc() or equivalent.

   Return the uncompressed size if the full section contents is

   compressed successfully.  Otherwise return (bfd_size_type) -1.  */

static bfd_size_type

bfd_compress_section_contents (bfd *abfd, sec_ptr sec)

{

  bfd_byte *input_buffer;

  uLong compressed_size;

  bfd_byte *buffer;

  bfd_size_type buffer_size;

  int zlib_size = 0;

  int orig_header_size;

  bfd_size_type uncompressed_size;

  unsigned int uncompressed_alignment_pow;

  enum compression_type ch_type = ch_none;

  int new_header_size = bfd_get_compression_header_size (abfd, NULL);

  bool compressed

    = bfd_is_section_compressed_info (abfd, sec,

              &orig_header_size,

              &uncompressed_size,

              &uncompressed_alignment_pow,

              &ch_type);

  bool update = false;

  /* We shouldn't be trying to decompress unsupported compressed sections.  */

  if (compressed && orig_header_size < 0)

    abort ();

  /* PR 31455: Check for a corrupt uncompressed size.  */

  if (uncompressed_size == (bfd_size_type) -1)

    return uncompressed_size;

  /* Either ELF compression header or the 12-byte, "ZLIB" + 8-byte size,

     overhead in .zdebug* section.  */

  if (!new_header_size)

    new_header_size = 12;

  if (ch_type == ch_none)

    orig_header_size = 12;

  input_buffer = sec->contents;

  if (compressed)

    {

      zlib_size = sec->size - orig_header_size;

      compressed_size = zlib_size + new_header_size;

      /* If we are converting between zlib-gnu and zlib-gabi then the

   compressed contents just need to be moved.  */

      update = (ch_type < ch_compress_zstd

    && (abfd->flags & BFD_COMPRESS_ZSTD) == 0);

      /* Uncompress when not just moving contents or when compressed

   is not smaller than uncompressed.  */

      if (!update || compressed_size >= uncompressed_size)

  {

    buffer_size = uncompressed_size;

    buffer = bfd_malloc (buffer_size);

    if (buffer == NULL)

      return (bfd_size_type) -1;

    if (!decompress_contents (ch_type == ch_compress_zstd,

            input_buffer + orig_header_size,

            zlib_size, buffer, buffer_size))

      {

        bfd_set_error (bfd_error_bad_value);

        free (buffer);

        return (bfd_size_type) -1;

      }

    free (input_buffer);

    bfd_set_section_alignment (sec, uncompressed_alignment_pow);

    sec->contents = buffer;

    sec->flags |= SEC_IN_MEMORY;

    sec->compress_status = COMPRESS_SECTION_NONE;

    sec->size = uncompressed_size;

    input_buffer = buffer;

  }

    }

  if (!update)

    compressed_size = compressBound (uncompressed_size) + new_header_size;

  buffer_size = compressed_size;

  buffer = bfd_alloc (abfd, buffer_size);

  if (buffer == NULL)

    return (bfd_size_type) -1;

  if (update)

    {

      if (compressed_size < uncompressed_size)

  memcpy (buffer + new_header_size,

    input_buffer + orig_header_size,

    zlib_size);

    }

  else

    {

      if (abfd->flags & BFD_COMPRESS_ZSTD)

  {

#if HAVE_ZSTD

    compressed_size = ZSTD_compress (buffer + new_header_size,

             compressed_size,

             input_buffer,

             uncompressed_size,

             ZSTD_CLEVEL_DEFAULT);

    if (ZSTD_isError (compressed_size))

      {

        bfd_release (abfd, buffer);

        bfd_set_error (bfd_error_bad_value);

        return (bfd_size_type) -1;

      }

#endif

  }

      else if (compress ((Bytef *) buffer + new_header_size, &compressed_size,

       (const Bytef *) input_buffer, uncompressed_size)

         != Z_OK)

  {

    bfd_release (abfd, buffer);

    bfd_set_error (bfd_error_bad_value);

    return (bfd_size_type) -1;

  }

      compressed_size += new_header_size;

    }

  /* If compression didn't make the section smaller, keep it uncompressed.  */

  if (compressed_size >= uncompressed_size)

    {

      memcpy (buffer, input_buffer, uncompressed_size);

      if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)

  elf_section_flags (sec) &= ~SHF_COMPRESSED;

      sec->compress_status = COMPRESS_SECTION_NONE;

    }

  else

    {

      sec->size = uncompressed_size;

      bfd_update_compression_header (abfd, buffer, sec);

      sec->size = compressed_size;

      sec->compress_status = COMPRESS_SECTION_DONE;

    }

  sec->contents = buffer;

  sec->flags |= SEC_IN_MEMORY;

  free (input_buffer);

  return uncompressed_size;

}

/*

FUNCTION

  bfd_get_full_section_contents

SYNOPSIS

  bool bfd_get_full_section_contents

    (bfd *abfd, asection *section, bfd_byte **ptr);

DESCRIPTION

  Read all data from @var{section} in BFD @var{abfd}, decompress

  if needed, and store in @var{*ptr}.  If @var{*ptr} is NULL,

  return @var{*ptr} with memory malloc'd by this function.

  Return @code{TRUE} if the full section contents is retrieved

  successfully.  If the section has no contents then this function

  returns @code{TRUE} but @var{*ptr} is set to NULL.

*/

bool

bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)

{

  bfd_size_type readsz = bfd_get_section_limit_octets (abfd, sec);

  bfd_size_type allocsz = bfd_get_section_alloc_size (abfd, sec);

  bfd_byte *p = *ptr;

  bool ret;

  bfd_size_type save_size;

  bfd_size_type save_rawsize;

  bfd_byte *compressed_buffer;

  unsigned int compression_header_size;

  const unsigned int compress_status = sec->compress_status;

  if (allocsz == 0)

    {

      *ptr = NULL;

      return true;

    }

  if (p == NULL

      && compress_status != COMPRESS_SECTION_DONE

      && bfd_section_size_insane (abfd, sec))

    {

      /* PR 24708: Avoid attempts to allocate a ridiculous amount

   of memory.  */

      _bfd_error_handler

  /* xgettext:c-format */

  (_("error: %pB(%pA) is too large (%#" PRIx64 " bytes)"),

   abfd, sec, (uint64_t) readsz);

      return false;

    }

  switch (compress_status)

    {

    case COMPRESS_SECTION_NONE:

      if (p == NULL && !sec->mmapped_p)

  {

    p = (bfd_byte *) bfd_malloc (allocsz);

    if (p == NULL)

      {

        /* PR 20801: Provide a more helpful error message.  */

        if (bfd_get_error () == bfd_error_no_memory)

    _bfd_error_handler

      /* xgettext:c-format */

      (_("error: %pB(%pA) is too large (%#" PRIx64 " bytes)"),

      abfd, sec, (uint64_t) allocsz);

        return false;

      }

  }

      if (!bfd_get_section_contents (abfd, sec, p, 0, readsz))

  {

    if (*ptr != p)

      free (p);

    return false;

  }

      *ptr = p;

      return true;

    case DECOMPRESS_SECTION_ZLIB:

    case DECOMPRESS_SECTION_ZSTD:

      /* Read in the full compressed section contents.  */

      compressed_buffer = (bfd_byte *) bfd_malloc (sec->compressed_size);

      if (compressed_buffer == NULL)

  return false;

      save_rawsize = sec->rawsize;

      save_size = sec->size;

      /* Clear rawsize, set size to compressed size and set compress_status

   to COMPRESS_SECTION_NONE.  If the compressed size is bigger than

   the uncompressed size, bfd_get_section_contents will fail.  */

      sec->rawsize = 0;

      sec->size = sec->compressed_size;

      sec->compress_status = COMPRESS_SECTION_NONE;

      ret = bfd_get_section_contents (abfd, sec, compressed_buffer,

              0, sec->compressed_size);

      /* Restore rawsize and size.  */

      sec->rawsize = save_rawsize;

      sec->size = save_size;

      sec->compress_status = compress_status;

      if (!ret)

  goto fail_compressed;

      if (p == NULL)

  p = (bfd_byte *) bfd_malloc (allocsz);

      if (p == NULL)

  goto fail_compressed;

      compression_header_size = bfd_get_compression_header_size (abfd, sec);

      if (compression_header_size == 0)

  /* Set header size to the zlib header size if it is a

     SHF_COMPRESSED section.  */

  compression_header_size = 12;

      bool is_zstd = compress_status == DECOMPRESS_SECTION_ZSTD;

      if (!decompress_contents (

        is_zstd, compressed_buffer + compression_header_size,

        sec->compressed_size - compression_header_size, p, readsz))

  {

    bfd_set_error (bfd_error_bad_value);

    if (p != *ptr)

      free (p);

  fail_compressed:

    free (compressed_buffer);

    return false;

  }

      free (compressed_buffer);

      *ptr = p;

      return true;

    case COMPRESS_SECTION_DONE:

      if (sec->contents == NULL)

  return false;

      if (p == NULL)

  {

    p = (bfd_byte *) bfd_malloc (allocsz);

    if (p == NULL)

      return false;

    *ptr = p;

  }

      /* PR 17512; file: 5bc29788.  */

      if (p != sec->contents)

  memcpy (p, sec->contents, readsz);

      return true;

    default:

      abort ();

    }

}

/*

FUNCTION

  bfd_is_section_compressed_info

SYNOPSIS

  bool bfd_is_section_compressed_info

    (bfd *abfd, asection *section,

     int *compression_header_size_p,

     bfd_size_type *uncompressed_size_p,

     unsigned int *uncompressed_alignment_power_p,

     enum compression_type *ch_type);

DESCRIPTION

  Return @code{TRUE} if @var{section} is compressed.  Compression

  header size is returned in @var{compression_header_size_p},

  uncompressed size is returned in @var{uncompressed_size_p}

  and the uncompressed data alignement power is returned in

  @var{uncompressed_align_pow_p}.  If compression is

  unsupported, compression header size is returned with -1

  and uncompressed size is returned with 0.

*/

bool

bfd_is_section_compressed_info (bfd *abfd, sec_ptr sec,

        int *compression_header_size_p,

        bfd_size_type *uncompressed_size_p,

        unsigned int *uncompressed_align_pow_p,

        enum compression_type *ch_type)

{

  bfd_byte header[MAX_COMPRESSION_HEADER_SIZE];

  int compression_header_size;

  int header_size;

  unsigned int saved = sec->compress_status;

  bool compressed;

  *uncompressed_align_pow_p = 0;

  compression_header_size = bfd_get_compression_header_size (abfd, sec);

  if (compression_header_size > MAX_COMPRESSION_HEADER_SIZE)

    abort ();

  header_size = compression_header_size ? compression_header_size : 12;

  /* Don't decompress the section.  */

  sec->compress_status = COMPRESS_SECTION_NONE;

  /* Read the header.  */

  if (bfd_get_section_contents (abfd, sec, header, 0, header_size))

    {

      if (compression_header_size == 0)

  /* In this case, it should be "ZLIB" followed by the uncompressed

     section size, 8 bytes in big-endian order.  */

  compressed = startswith ((char*) header , "ZLIB");

      else

  compressed = true;

    }

  else

    compressed = false;

  *uncompressed_size_p = sec->size;

  if (compressed)

    {

      if (compression_header_size != 0)

  {

    if (!bfd_check_compression_header (abfd, header, sec, ch_type,

               uncompressed_size_p,

               uncompressed_align_pow_p))

      compression_header_size = -1;

  }

      /* Check for the pathalogical case of a debug string section that

   contains the string ZLIB.... as the first entry.  We assume that

   no uncompressed .debug_str section would ever be big enough to

   have the first byte of its (big-endian) size be non-zero.  */

      else if (strcmp (sec->name, ".debug_str") == 0

         && ISPRINT (header[4]))

  compressed = false;

      else

  *uncompressed_size_p = bfd_getb64 (header + 4);

    }

  /* Restore compress_status.  */

  sec->compress_status = saved;

  *compression_header_size_p = compression_header_size;

  return compressed;

}

/*

FUNCTION

  bfd_is_section_compressed

SYNOPSIS

  bool bfd_is_section_compressed

    (bfd *abfd, asection *section);

DESCRIPTION

  Return @code{TRUE} if @var{section} is compressed.

*/

bool

bfd_is_section_compressed (bfd *abfd, sec_ptr sec)

{

  int compression_header_size;

  bfd_size_type uncompressed_size;

  unsigned int uncompressed_align_power;

  enum compression_type ch_type;

  return (bfd_is_section_compressed_info (abfd, sec,

            &compression_header_size,

            &uncompressed_size,

            &uncompressed_align_power,

            &ch_type)

    && compression_header_size >= 0

    && uncompressed_size > 0);

}

/*

FUNCTION

  bfd_init_section_decompress_status

SYNOPSIS

  bool bfd_init_section_decompress_status

    (bfd *abfd, asection *section);

DESCRIPTION

  Record compressed section size, update section size with

  decompressed size and set compress_status to

  DECOMPRESS_SECTION_{ZLIB,ZSTD}.

  Return @code{FALSE} if the section is not a valid compressed

  section.  Otherwise, return @code{TRUE}.

*/

bool

bfd_init_section_decompress_status (bfd *abfd, sec_ptr sec)

{

  bfd_byte header[MAX_COMPRESSION_HEADER_SIZE];

  int compression_header_size;

  int header_size;

  bfd_size_type uncompressed_size;

  unsigned int uncompressed_alignment_power = 0;

  enum compression_type ch_type;

  z_stream strm;

  compression_header_size = bfd_get_compression_header_size (abfd, sec);

  if (compression_header_size > MAX_COMPRESSION_HEADER_SIZE)

    abort ();