/* ld.so error exception allocation and deallocation.

   Copyright (C) 1995-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   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/>.  */

#include <ldsodefs.h>

#include <limits.h>

#include <stdarg.h>

#include <stdbool.h>

#include <stdint.h>

#include <string.h>

#include <unistd.h>

/* This message we return as a last resort.  We define the string in a

   variable since we have to avoid freeing it and so have to enable

   a pointer comparison.  See below and in dlfcn/dlerror.c.  */

static const char _dl_out_of_memory[] = "out of memory";

/* Dummy allocation object used if allocating the message buffer

   fails.  */

static void

oom_exception (struct dl_exception *exception)

{

  exception->objname = "";

  exception->errstring = _dl_out_of_memory;

  exception->message_buffer = NULL;

}

static void

__attribute__ ((noreturn))

length_mismatch (void)

{

  _dl_fatal_printf ("Fatal error: "

                    "length accounting in _dl_exception_create_format\n");

}

/* Adjust the message buffer to indicate whether it is possible to

   free it.  EXCEPTION->errstring must be a potentially deallocatable

   pointer.  */

static void

adjust_message_buffer (struct dl_exception *exception)

{

  /* If the main executable is relocated it means the libc's malloc

     is used.  */

  bool malloced = true;

#ifdef SHARED

  malloced = (GL(dl_ns)[LM_ID_BASE]._ns_loaded != NULL

              && (GL(dl_ns)[LM_ID_BASE]._ns_loaded->l_relocated != 0));

#endif

  if (malloced)

    exception->message_buffer = (char *) exception->errstring;

  else

    exception->message_buffer = NULL;

}

void

_dl_exception_create (struct dl_exception *exception, const char *objname,

                      const char *errstring)

{

  if (objname == NULL)

    objname = "";

  size_t len_objname = strlen (objname) + 1;

  size_t len_errstring = strlen (errstring) + 1;

  char *errstring_copy = malloc (len_objname + len_errstring);

  if (errstring_copy != NULL)

    {

      /* Make a copy of the object file name and the error string.  */

      exception->objname = memcpy (__mempcpy (errstring_copy,

                                              errstring, len_errstring),

                                   objname, len_objname);

      exception->errstring = errstring_copy;

      adjust_message_buffer (exception);

    }

  else

    oom_exception (exception);

}

rtld_hidden_def (_dl_exception_create)

void

_dl_exception_create_format (struct dl_exception *exception, const char *objname,

                             const char *fmt, ...)

{

  if (objname == NULL)

    objname = "";

  size_t len_objname = strlen (objname) + 1;

  /* Compute the length of the result.  Include room for two NUL

     bytes.  */

  size_t length = len_objname + 1;

  {

    va_list ap;

    va_start (ap, fmt);

    for (const char *p = fmt; *p != '\0'; ++p)

      if (*p == '%')

        {

          ++p;

          switch (*p)

            {

            case 's':

              length += strlen (va_arg (ap, const char *));

              break;

            default:

              /* Assumed to be '%'.  */

              ++length;

              break;

            }

        }

      else

        ++length;

    va_end (ap);

  }

  if (length > PTRDIFF_MAX)

    {

      oom_exception (exception);

      return;

    }

  char *errstring = malloc (length);

  if (errstring == NULL)

    {

      oom_exception (exception);

      return;

    }

  exception->errstring = errstring;

  adjust_message_buffer (exception);

  /* Copy the error message to errstring.  */

  {

    /* Next byte to be written in errstring.  */

    char *wptr = errstring;

    /* End of the allocated string.  */

    char *const end = errstring + length;

    va_list ap;

    va_start (ap, fmt);

    for (const char *p = fmt; *p != '\0'; ++p)

      if (*p == '%')

        {

          ++p;

          switch (*p)

            {

            case 's':

              {

                const char *ptr = va_arg (ap, const char *);

                size_t len_ptr = strlen (ptr);

                if (len_ptr > end - wptr)

                  length_mismatch ();

                wptr = __mempcpy (wptr, ptr, len_ptr);

              }

              break;

            case '%':

              if (wptr == end)

                length_mismatch ();

              *wptr = '%';

              ++wptr;

              break;

            default:

              _dl_fatal_printf ("Fatal error:"

                                " invalid format in exception string\n");

            }

        }

      else

        {

          if (wptr == end)

            length_mismatch ();

          *wptr = *p;

          ++wptr;

        }

    if (wptr == end)

      length_mismatch ();

    *wptr = '\0';

    ++wptr;

    if (len_objname != end - wptr)

      length_mismatch ();

    exception->objname = memcpy (wptr, objname, len_objname);

  }

}

rtld_hidden_def (_dl_exception_create_format)

void

_dl_exception_free (struct dl_exception *exception)

{

  free (exception->message_buffer);

  exception->objname = NULL;

  exception->errstring = NULL;

  exception->message_buffer = NULL;

}

rtld_hidden_def (_dl_exception_free)