elf/readlib.c

   1 /* Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Andreas Jaeger <aj@suse.de>, 1999 and
   4                   Jakub Jelinek <jakub@redhat.com>, 1999.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 /* The code in this file and in readelflib is a heavily simplified
  22    version of the readelf program that's part of the current binutils
  23    development version.  Besides the simplification, it has also been
  24    modified to read some other file formats.  */
  25
  26
  27 #include <elf.h>
  28 #include <error.h>
  29 #include <link.h>
  30 #include <libintl.h>
  31 #include <stdio.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34 #include <a.out.h>
  35
  36 #include <sys/mman.h>
  37 #include <sys/stat.h>
  38 #include <gnu/lib-names.h>
  39
  40 #include "ldconfig.h"
  41
  42 #define Elf32_CLASS ELFCLASS32
  43 #define Elf64_CLASS ELFCLASS64
  44
  45 struct known_names
  46 {
  47   const char *soname;
  48   int flag;
  49 };
  50
  51 static struct known_names interpreters[] =
  52 {
  53   { "/lib/" LD_SO, FLAG_ELF_LIBC6 },
  54 #ifdef SYSDEP_KNOWN_INTERPRETER_NAMES
  55   SYSDEP_KNOWN_INTERPRETER_NAMES
  56 #endif
  57 };
  58
  59 static struct known_names known_libs[] =
  60 {
  61   { LIBC_SO, FLAG_ELF_LIBC6 },
  62   { LIBM_SO, FLAG_ELF_LIBC6 },
  63 #ifdef SYSDEP_KNOWN_LIBRARY_NAMES
  64   SYSDEP_KNOWN_LIBRARY_NAMES
  65 #endif
  66 };
  67
  68
  69
  70 /* Returns 0 if everything is ok, != 0 in case of error.  */
  71 int
  72 process_file (const char *real_file_name, const char *file_name,
  73               const char *lib, int *flag, unsigned int *osversion,
  74               char **soname, int is_link)
  75 {
  76   FILE *file;
  77   struct stat64 statbuf;
  78   void *file_contents;
  79   int ret;
  80   ElfW(Ehdr) *elf_header;
  81   struct exec *aout_header;
  82
  83   ret = 0;
  84   *flag = FLAG_ANY;
  85   *soname = NULL;
  86
  87   file = fopen (real_file_name, "rb");
  88   if (file == NULL)
  89     {
  90       /* No error for stale symlink.  */
  91       if (is_link && strstr (file_name, ".so") != NULL)
  92         return 1;
  93       error (0, 0, _("Input file %s not found.\n"), file_name);
  94       return 1;
  95     }
  96
  97   if (fstat64 (fileno (file), &statbuf) < 0)
  98     {
  99       error (0, 0, _("Cannot fstat file %s.\n"), file_name);
 100       fclose (file);
 101       return 1;
 102     }
 103
 104   /* Check that the file is large enough so that we can access the
 105      information.  We're only checking the size of the headers here.  */
 106   if (statbuf.st_size < sizeof (struct exec)
 107       || statbuf.st_size < sizeof (ElfW(Ehdr)))
 108     {
 109       error (0, 0, _("File %s is too small, not checked."), file_name);
 110       fclose (file);
 111       return 1;
 112     }
 113
 114   file_contents = mmap (0, statbuf.st_size, PROT_READ, MAP_SHARED,
 115                         fileno (file), 0);
 116   if (file_contents == MAP_FAILED)
 117     {
 118       error (0, 0, _("Cannot mmap file %s.\n"), file_name);
 119       fclose (file);
 120       return 1;
 121     }
 122
 123   /* First check if this is an aout file.  */
 124   aout_header = (struct exec *) file_contents;
 125   if (N_MAGIC (*aout_header) == ZMAGIC
 126       || N_MAGIC (*aout_header) == QMAGIC)
 127     {
 128       /* Aout files don't have a soname, just return the name
 129          including the major number.  */
 130       char *copy, *major, *dot;
 131       copy = xstrdup (lib);
 132       major = strstr (copy, ".so.");
 133       if (major)
 134         {
 135           dot = strstr (major + 4, ".");
 136           if (dot)
 137             *dot = '\0';
 138         }
 139       *soname = copy;
 140       *flag = FLAG_LIBC4;
 141       goto done;
 142     }
 143
 144   elf_header = (ElfW(Ehdr) *) file_contents;
 145   if (memcmp (elf_header->e_ident, ELFMAG, SELFMAG) != 0)
 146     {
 147       /* The file is neither ELF nor aout.  Check if it's a linker script,
 148          like libc.so - otherwise complain.  */
 149       int len = statbuf.st_size;
 150       /* Only search the beginning of the file.  */
 151       if (len > 512)
 152         len = 512;
 153       if (memmem (file_contents, len, "GROUP", 5) == NULL
 154           && memmem (file_contents, len, "GNU ld script", 13) == NULL)
 155         error (0, 0, _("%s is not an ELF file - it has the wrong magic bytes at the start.\n"),
 156                file_name);
 157       ret = 1;
 158       goto done;
 159     }
 160
 161   if (process_elf_file (file_name, lib, flag, osversion, soname,
 162                         file_contents, statbuf.st_size))
 163     ret = 1;
 164
 165  done:
 166   /* Clean up allocated memory and resources.  */
 167   munmap (file_contents, statbuf.st_size);
 168   fclose (file);
 169
 170   return ret;
 171 }
 172
 173 /* Get architecture specific version of process_elf_file.  */
 174 #include "readelflib.c"