elf/readlib.c

   1 /* Copyright (C) 1999, 2000, 2001, 2002, 2003 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 #include <a.out.h>
  27 #include <elf.h>
  28 #include <error.h>
  29 #include <libintl.h>
  30 #include <link.h>
  31 #include <stdio.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34 #include <sys/mman.h>
  35 #include <sys/param.h>
  36 #include <sys/stat.h>
  37 #include <gnu/lib-names.h>
  38
  39 #include "ldconfig.h"
  40
  41 #define Elf32_CLASS ELFCLASS32
  42 #define Elf64_CLASS ELFCLASS64
  43
  44 struct known_names
  45 {
  46   const char *soname;
  47   int flag;
  48 };
  49
  50 static struct known_names interpreters[] =
  51 {
  52   { "/lib/" LD_SO, FLAG_ELF_LIBC6 },
  53 #ifdef SYSDEP_KNOWN_INTERPRETER_NAMES
  54   SYSDEP_KNOWN_INTERPRETER_NAMES
  55 #endif
  56 };
  57
  58 static struct known_names known_libs[] =
  59 {
  60   { LIBC_SO, FLAG_ELF_LIBC6 },
  61   { LIBM_SO, FLAG_ELF_LIBC6 },
  62 #ifdef SYSDEP_KNOWN_LIBRARY_NAMES
  63   SYSDEP_KNOWN_LIBRARY_NAMES
  64 #endif
  65 };
  66
  67
  68
  69 /* Returns 0 if everything is ok, != 0 in case of error.  */
  70 int
  71 process_file (const char *real_file_name, const char *file_name,
  72               const char *lib, int *flag, unsigned int *osversion,
  73               char **soname, int is_link)
  74 {
  75   FILE *file;
  76   struct stat64 statbuf;
  77   void *file_contents;
  78   int ret;
  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 (real_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 (fstat64 (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 ((size_t) statbuf.st_size < sizeof (struct exec)
 106       || (size_t) statbuf.st_size < sizeof (ElfW(Ehdr)))
 107     {
 108       if (statbuf.st_size == 0)
 109         error (0, 0, _("File %s is empty, not checked."), file_name);
 110       else
 111         {
 112           char buf[SELFMAG];
 113           size_t n = MIN (statbuf.st_size, SELFMAG);
 114           if (fread (buf, n, 1, file) == 1 && memcmp (buf, ELFMAG, n) == 0)
 115             error (0, 0, _("File %s is too small, not checked."), file_name);
 116         }
 117       fclose (file);
 118       return 1;
 119     }
 120
 121   file_contents = mmap (0, statbuf.st_size, PROT_READ, MAP_SHARED,
 122                         fileno (file), 0);
 123   if (file_contents == MAP_FAILED)
 124     {
 125       error (0, 0, _("Cannot mmap file %s.\n"), file_name);
 126       fclose (file);
 127       return 1;
 128     }
 129
 130   /* First check if this is an aout file.  */
 131   aout_header = (struct exec *) file_contents;
 132   if (N_MAGIC (*aout_header) == ZMAGIC
 133 #ifdef QMAGIC                   /* Linuxism.  */
 134       || N_MAGIC (*aout_header) == QMAGIC
 135 #endif
 136       )
 137     {
 138       /* Aout files don't have a soname, just return the name
 139          including the major number.  */
 140       char *copy, *major, *dot;
 141       copy = xstrdup (lib);
 142       major = strstr (copy, ".so.");
 143       if (major)
 144         {
 145           dot = strstr (major + 4, ".");
 146           if (dot)
 147             *dot = '\0';
 148         }
 149       *soname = copy;
 150       *flag = FLAG_LIBC4;
 151       goto done;
 152     }
 153
 154   elf_header = (ElfW(Ehdr) *) file_contents;
 155   if (memcmp (elf_header->e_ident, ELFMAG, SELFMAG) != 0)
 156     {
 157       /* The file is neither ELF nor aout.  Check if it's a linker
 158          script, like libc.so - otherwise complain.  Only search the
 159          beginning of the file.  */
 160       size_t len = MIN (statbuf.st_size, 512);
 161       if (memmem (file_contents, len, "GROUP", 5) == NULL
 162           && memmem (file_contents, len, "GNU ld script", 13) == NULL)
 163         error (0, 0, _("%s is not an ELF file - it has the wrong magic bytes at the start.\n"),
 164                file_name);
 165       ret = 1;
 166     }
 167   /* Libraries have to be shared object files.  */
 168   else if (elf_header->e_type != ET_DYN)
 169     ret = 1;
 170   else if (process_elf_file (file_name, lib, flag, osversion, soname,
 171                              file_contents, statbuf.st_size))
 172     ret = 1;
 173
 174  done:
 175   /* Clean up allocated memory and resources.  */
 176   munmap (file_contents, statbuf.st_size);
 177   fclose (file);
 178
 179   return ret;
 180 }
 181
 182 /* Get architecture specific version of process_elf_file.  */
 183 #include "readelflib.c"