elf/readlib.c

   1 /* Copyright (C) 1999, 2000 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 Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 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   {"/lib/ld-linux.so.1", FLAG_ELF_LIBC5}
  55 };
  56
  57 static struct known_names known_libs [] =
  58 {
  59   /* Old names:  */
  60   {"libc.so.5", FLAG_ELF_LIBC5},
  61   {"libm.so.5", FLAG_ELF_LIBC5},
  62   /* Current names:  */
  63   {LIBC_SO, FLAG_ELF_LIBC6},
  64   {LIBM_SO, FLAG_ELF_LIBC6}
  65 };
  66
  67
  68
  69 /* Returns 0 if everything is ok, != 0 in case of error.  */
  70 int
  71 process_file (const char *file_name, const char *lib, int *flag,
  72               char **soname, int is_link)
  73 {
  74   FILE *file;
  75   struct stat statbuf;
  76   void *file_contents;
  77   int ret;
  78
  79   ElfW(Ehdr) *elf_header;
  80   struct exec *aout_header;
  81
  82   ret = 0;
  83   *flag = FLAG_ANY;
  84   *soname = NULL;
  85
  86   file = fopen (file_name, "rb");
  87   if (file == NULL)
  88     {
  89       /* No error for stale symlink.  */
  90       if (is_link && strstr (file_name, ".so.") != NULL)
  91         return 1;
  92       error (0, 0, _("Input file %s not found.\n"), file_name);
  93       return 1;
  94     }
  95
  96   if (fstat (fileno (file), &statbuf) < 0)
  97     {
  98       error (0, 0, _("Cannot fstat file %s.\n"), file_name);
  99       fclose (file);
 100       return 1;
 101     }
 102
 103   /* Check that the file is large enough so that we can access the
 104      information.  We're only checking the size of the headers here.  */
 105   if (statbuf.st_size < sizeof (struct exec)
 106       || statbuf.st_size < sizeof (ElfW(Ehdr)))
 107     {
 108       error (0, 0, _("File %s is too small, not checked."), file_name);
 109       fclose (file);
 110       return 1;
 111     }
 112
 113   file_contents = mmap (0, statbuf.st_size, PROT_READ, MAP_SHARED,
 114                         fileno (file), 0);
 115   if (file_contents == MAP_FAILED)
 116     {
 117       error (0, 0, _("Cannot mmap file %s.\n"), file_name);
 118       fclose (file);
 119       return 1;
 120     }
 121
 122   /* First check if this is an aout file.  */
 123   aout_header = (struct exec *) file_contents;
 124   if (N_MAGIC (*aout_header) == ZMAGIC
 125       || N_MAGIC (*aout_header) == QMAGIC)
 126     {
 127       /* Aout files don't have a soname, just return the name
 128          including the major number.  */
 129       char *copy, *major, *dot;
 130       copy = xstrdup (lib);
 131       major = strstr (copy, ".so.");
 132       if (major)
 133         {
 134           dot = strstr (major + 4, ".");
 135           if (dot)
 136             *dot = '\0';
 137         }
 138       *soname = copy;
 139       *flag = FLAG_LIBC4;
 140       goto done;
 141     }
 142
 143   elf_header = (ElfW(Ehdr) *) file_contents;
 144   if (elf_header->e_ident [EI_MAG0] != ELFMAG0
 145       || elf_header->e_ident [EI_MAG1] != ELFMAG1
 146       || elf_header->e_ident [EI_MAG2] != ELFMAG2
 147       || elf_header->e_ident [EI_MAG3] != ELFMAG3)
 148     {
 149       /* The file is neither ELF nor aout.  Check if it's a linker script,
 150          like libc.so - otherwise complain.  */
 151       int len = statbuf.st_size;
 152       /* Only search the beginning of the file.  */
 153       if (len > 512)
 154         len = 512;
 155       if (memmem (file_contents, len, "GROUP", 5) == NULL
 156           && memmem (file_contents, len, "GNU ld script", 13) == NULL)
 157         error (0, 0, _("%s is not an ELF file - it has the wrong magic bytes at the start.\n"),
 158                file_name);
 159       ret = 1;
 160       goto done;
 161     }
 162
 163   if (process_elf_file (file_name, lib, flag, soname, file_contents,
 164                         statbuf.st_size))
 165     ret = 1;
 166
 167  done:
 168   /* Clean up allocated memory and resources.  */
 169   munmap (file_contents, statbuf.st_size);
 170   fclose (file);
 171
 172   return ret;
 173 }
 174
 175 /* Get architecture specific version of process_elf_file.  */
 176 #include "readelflib.c"