glibc/sysdeps/unix/nlist.c

/* Copyright (C) 1991, 1996, 1997 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 Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <errno.h>
#include <a.out.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>


/* Search the executable FILE for symbols matching those in NL,
   which is terminated by an element with a NULL `n_un.n_name' member,
   and fill in the elements of NL.  */
int
nlist (const char *file, struct nlist *nl)
{
  FILE *f;
  struct exec header;
  size_t nsymbols;
  struct nlist *symbols;
  unsigned long int string_table_size;
  char *string_table;
  register size_t i;

  if (nl == NULL)
    {
      __set_errno (EINVAL);
      return -1;
    }

  f = fopen (file, "r");
  if (f == NULL)
    return -1;

  if (fread ((void *) &header, sizeof (header), 1, f) != 1)
    goto lose;

  if (fseek (f, N_SYMOFF (header), SEEK_SET) != 0)
    goto lose;

  symbols = (struct nlist *) __alloca (header.a_syms);
  nsymbols = header.a_syms / sizeof (symbols[0]);

  if (fread ((void *) symbols, sizeof (symbols[0]), nsymbols, f) != nsymbols)
    goto lose;

  if (fread ((void *) &string_table_size, sizeof (string_table_size), 1, f)
      != 1)
    goto lose;
  string_table_size -= sizeof (string_table_size);

  string_table = (char *) __alloca (string_table_size);
  if (fread ((void *) string_table, string_table_size, 1, f) != 1)
    goto lose;

  for (i = 0; i < nsymbols; ++i)
    {
      register struct nlist *nlp;
      for (nlp = nl; nlp->n_un.n_name != NULL; ++nlp)
	if (!strcmp (nlp->n_un.n_name,
		     &string_table[symbols[i].n_un.n_strx -
				  sizeof (string_table_size)]))
	  {
	    char *const name = nlp->n_un.n_name;
	    *nlp = symbols[i];
	    nlp->n_un.n_name = name;
	  }
    }

  (void) fclose (f);
  return 0;

 lose:;
  (void) fclose (f);
  return -1;
}