/* Copyright (C) 2011-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

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

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#define E(name) E_(name, CLASS)

#define E_(name, cl) E__(name, cl)

#define E__(name, cl) name##cl

#define EW(type) EW_(Elf, CLASS, type)

#define EW_(e, w, t) EW__(e, w, _##t)

#define EW__(e, w, t) e##w##t

#define pldd_assert(name, exp) \

  typedef int __assert_##name[((exp) != 0) - 1]

struct E(link_map)

{

  EW(Addr) l_addr;

  EW(Addr) l_name;

  EW(Addr) l_ld;

  EW(Addr) l_next;

  EW(Addr) l_prev;

  EW(Addr) l_real;

  Lmid_t l_ns;

  EW(Addr) l_libname;

};

#if CLASS == __ELF_NATIVE_CLASS

pldd_assert (l_addr, (offsetof (struct link_map, l_addr)

			== offsetof (struct E(link_map), l_addr)));

pldd_assert (l_name, (offsetof (struct link_map, l_name)

			== offsetof (struct E(link_map), l_name)));

pldd_assert (l_next, (offsetof (struct link_map, l_next)

			== offsetof (struct E(link_map), l_next)));

#endif

struct E(libname_list)

{

  EW(Addr) name;

  EW(Addr) next;

};

#if CLASS == __ELF_NATIVE_CLASS

pldd_assert (name, (offsetof (struct libname_list, name)

		      == offsetof (struct E(libname_list), name)));

pldd_assert (next, (offsetof (struct libname_list, next)

		      == offsetof (struct E(libname_list), next)));

#endif

struct E(r_debug)

{

  int r_version;

#if CLASS == 64

  int pad;

#endif

  EW(Addr) r_map;

};

#if CLASS == __ELF_NATIVE_CLASS

pldd_assert (r_version, (offsetof (struct r_debug, r_version)

			   == offsetof (struct E(r_debug), r_version)));

pldd_assert (r_map, (offsetof (struct r_debug, r_map)

		       == offsetof (struct E(r_debug), r_map)));

#endif

static int

E(find_maps) (pid_t pid, void *auxv, size_t auxv_size)

{

  EW(Addr) phdr = 0;

  unsigned int phnum = 0;

  unsigned int phent = 0;

  EW(auxv_t) *auxvXX = (EW(auxv_t) *) auxv;

  for (int i = 0; i < auxv_size / sizeof (EW(auxv_t)); ++i)

    switch (auxvXX[i].a_type)

      {

      case AT_PHDR:

	phdr = auxvXX[i].a_un.a_val;

	break;

      case AT_PHNUM:

	phnum = auxvXX[i].a_un.a_val;

	break;

      case AT_PHENT:

	phent = auxvXX[i].a_un.a_val;

	break;

      default:

	break;

      }

  if (phdr == 0 || phnum == 0 || phent == 0)

    error (EXIT_FAILURE, 0, gettext ("cannot find program header of process"));

  EW(Phdr) *p = alloca (phnum * phent);

  if (pread64 (memfd, p, phnum * phent, phdr) != phnum * phent)

    {

      error (0, 0, gettext ("cannot read program header"));

      return EXIT_FAILURE;

    }

  /* Determine the load offset.  We need this for interpreting the

     other program header entries so we do this in a separate loop.

     Fortunately it is the first time unless someone does something

     stupid when linking the application.  */

  EW(Addr) offset = 0;

  for (unsigned int i = 0; i < phnum; ++i)

    if (p[i].p_type == PT_PHDR)

      {

	offset = phdr - p[i].p_vaddr;

	break;

      }

  EW(Addr) list = 0;

  char *interp = NULL;

  for (unsigned int i = 0; i < phnum; ++i)

    if (p[i].p_type == PT_DYNAMIC)

      {

	EW(Dyn) *dyn = xmalloc (p[i].p_filesz);

	if (pread64 (memfd, dyn, p[i].p_filesz, offset + p[i].p_vaddr)

	    != p[i].p_filesz)

	  {

	    error (0, 0, gettext ("cannot read dynamic section"));

	    return EXIT_FAILURE;

	  }

	/* Search for the DT_DEBUG entry.  */

	for (unsigned int j = 0; j < p[i].p_filesz / sizeof (EW(Dyn)); ++j)

	  if (dyn[j].d_tag == DT_DEBUG && dyn[j].d_un.d_ptr != 0)

	    {

	      struct E(r_debug) r;

	      if (pread64 (memfd, &r, sizeof (r), dyn[j].d_un.d_ptr)

		  != sizeof (r))

		{

		  error (0, 0, gettext ("cannot read r_debug"));

		  return EXIT_FAILURE;

		}

	      if (r.r_map != 0)

		{

		  list = r.r_map;

		  break;

		}

	    }

	free (dyn);

	break;

      }

    else if (p[i].p_type == PT_INTERP)

      {

	interp = alloca (p[i].p_filesz);

	if (pread64 (memfd, interp, p[i].p_filesz, offset + p[i].p_vaddr)

	    != p[i].p_filesz)

	  {

	    error (0, 0, gettext ("cannot read program interpreter"));

	    return EXIT_FAILURE;

	  }

      }

  if (list == 0)

    {

      if (interp == NULL)

	{

	  // XXX check whether the executable itself is the loader

	  return EXIT_FAILURE;

	}

      // XXX perhaps try finding ld.so and _r_debug in it

      return EXIT_FAILURE;

    }

  /* Print the PID and program name first.  */

  printf ("%lu:\t%s\n", (unsigned long int) pid, exe);

  /* Iterate over the list of objects and print the information.  */

  struct scratch_buffer tmpbuf;

  scratch_buffer_init (&tmpbuf);

  int status = 0;

  do

    {

      struct E(link_map) m;

      if (pread64 (memfd, &m, sizeof (m), list) != sizeof (m))

	{

	  error (0, 0, gettext ("cannot read link map"));

	  status = EXIT_FAILURE;

	  goto out;

	}

      EW(Addr) name_offset = m.l_name;

    again:

      while (1)

	{

	  ssize_t n = pread64 (memfd, tmpbuf.data, tmpbuf.length, name_offset);

	  if (n == -1)

	    {

	      error (0, 0, gettext ("cannot read object name"));

	      status = EXIT_FAILURE;

	      goto out;

	    }

	  if (memchr (tmpbuf.data, '\0', n) != NULL)

	    break;

	  if (!scratch_buffer_grow (&tmpbuf))

	    {

	      error (0, 0, gettext ("cannot allocate buffer for object name"));

	      status = EXIT_FAILURE;

	      goto out;

	    }

	}

      if (((char *)tmpbuf.data)[0] == '\0' && name_offset == m.l_name

	  && m.l_libname != 0)

	{

	  /* Try the l_libname element.  */

	  struct E(libname_list) ln;

	  if (pread64 (memfd, &ln, sizeof (ln), m.l_libname) == sizeof (ln))

	    {

	      name_offset = ln.name;

	      goto again;

	    }

	}

      /* Skip over the executable.  */

      if (((char *)tmpbuf.data)[0] != '\0')

	printf ("%s\n", (char *)tmpbuf.data);

      list = m.l_next;

    }

  while (list != 0);

 out:

  scratch_buffer_free (&tmpbuf);

  return status;

}

#undef CLASS