elf/readlib.c

   1 /* Copyright (C) 1999-2003, 2005, 2007 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    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published
   8    by the Free Software Foundation; version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program 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
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 /* The code in this file and in readelflib is a heavily simplified
  21    version of the readelf program that's part of the current binutils
  22    development version.  Besides the simplification, it has also been
  23    modified to read some other file formats.  */
  24
  25 #include <a.out.h>
  26 #include <elf.h>
  27 #include <error.h>
  28 #include <libintl.h>
  29 #include <link.h>
  30 #include <stdio.h>
  31 #include <string.h>
  32 #include <unistd.h>
  33 #include <sys/mman.h>
  34 #include <sys/param.h>
  35 #include <sys/stat.h>
  36 #include <gnu/lib-names.h>
  37
  38 #include <ldconfig.h>
  39
  40 #define Elf32_CLASS ELFCLASS32
  41 #define Elf64_CLASS ELFCLASS64
  42
  43 struct known_names
  44 {
  45   const char *soname;
  46   int flag;
  47 };
  48
  49 static struct known_names interpreters[] =
  50 {
  51   { "/lib/" LD_SO, FLAG_ELF_LIBC6 },
  52 #ifdef SYSDEP_KNOWN_INTERPRETER_NAMES
  53   SYSDEP_KNOWN_INTERPRETER_NAMES
  54 #endif
  55 };
  56
  57 static struct known_names known_libs[] =
  58 {
  59   { LIBC_SO, FLAG_ELF_LIBC6 },
  60   { LIBM_SO, FLAG_ELF_LIBC6 },
  61 #ifdef SYSDEP_KNOWN_LIBRARY_NAMES
  62   SYSDEP_KNOWN_LIBRARY_NAMES
  63 #endif
  64 };
  65
  66
  67
  68 /* Returns 0 if everything is ok, != 0 in case of error.  */
  69 int
  70 process_file (const char *real_file_name, const char *file_name,
  71               const char *lib, int *flag, unsigned int *osversion,
  72               char **soname, int is_link, struct stat64 *stat_buf)
  73 {
  74   FILE *file;
  75   struct stat64 statbuf;
  76   void *file_contents;
  77   int ret;
  78   ElfW(Ehdr) *elf_header;
  79   struct exec *aout_header;
  80
  81   ret = 0;
  82   *flag = FLAG_ANY;
  83   *soname = NULL;
  84
  85   file = fopen (real_file_name, "rb");
  86   if (file == NULL)
  87     {
  88       /* No error for stale symlink.  */
  89       if (is_link && strstr (file_name, ".so") != NULL)
  90         return 1;
  91       error (0, 0, _("Input file %s not found.\n"), file_name);
  92       return 1;
  93     }
  94
  95   if (fstat64 (fileno (file), &statbuf) < 0)
  96     {
  97       error (0, 0, _("Cannot fstat file %s.\n"), file_name);
  98       fclose (file);
  99       return 1;
 100     }
 101
 102   /* Check that the file is large enough so that we can access the
 103      information.  We're only checking the size of the headers here.  */
 104   if ((size_t) statbuf.st_size < sizeof (struct exec)
 105       || (size_t) statbuf.st_size < sizeof (ElfW(Ehdr)))
 106     {
 107       if (statbuf.st_size == 0)
 108         error (0, 0, _("File %s is empty, not checked."), file_name);
 109       else
 110         {
 111           char buf[SELFMAG];
 112           size_t n = MIN (statbuf.st_size, SELFMAG);
 113           if (fread (buf, n, 1, file) == 1 && memcmp (buf, ELFMAG, n) == 0)
 114             error (0, 0, _("File %s is too small, not checked."), file_name);
 115         }
 116       fclose (file);
 117       return 1;
 118     }
 119
 120   file_contents = mmap (0, statbuf.st_size, PROT_READ, MAP_SHARED,
 121                         fileno (file), 0);
 122   if (file_contents == MAP_FAILED)
 123     {
 124       error (0, 0, _("Cannot mmap file %s.\n"), file_name);
 125       fclose (file);
 126       return 1;
 127     }
 128
 129   /* First check if this is an aout file.  */
 130   aout_header = (struct exec *) file_contents;
 131   if (N_MAGIC (*aout_header) == ZMAGIC
 132 #ifdef QMAGIC                   /* Linuxism.  */
 133       || N_MAGIC (*aout_header) == QMAGIC
 134 #endif
 135       )
 136     {
 137       /* Aout files don't have a soname, just return the name
 138          including the major number.  */
 139       char *copy, *major, *dot;
 140       copy = xstrdup (lib);
 141       major = strstr (copy, ".so.");
 142       if (major)
 143         {
 144           dot = strstr (major + 4, ".");
 145           if (dot)
 146             *dot = '\0';
 147         }
 148       *soname = copy;
 149       *flag = FLAG_LIBC4;
 150       goto done;
 151     }
 152
 153   elf_header = (ElfW(Ehdr) *) file_contents;
 154   if (memcmp (elf_header->e_ident, ELFMAG, SELFMAG) != 0)
 155     {
 156       /* The file is neither ELF nor aout.  Check if it's a linker
 157          script, like libc.so - otherwise complain.  Only search the
 158          beginning of the file.  */
 159       size_t len = MIN (statbuf.st_size, 512);
 160       if (memmem (file_contents, len, "GROUP", 5) == NULL
 161           && memmem (file_contents, len, "GNU ld script", 13) == NULL)
 162         error (0, 0, _("%s is not an ELF file - it has the wrong magic bytes at the start.\n"),
 163                file_name);
 164       ret = 1;
 165     }
 166   /* Libraries have to be shared object files.  */
 167   else if (elf_header->e_type != ET_DYN)
 168     ret = 1;
 169   else if (process_elf_file (file_name, lib, flag, osversion, soname,
 170                              file_contents, statbuf.st_size))
 171     ret = 1;
 172
 173  done:
 174   /* Clean up allocated memory and resources.  */
 175   munmap (file_contents, statbuf.st_size);
 176   fclose (file);
 177
 178   *stat_buf = statbuf;
 179   return ret;
 180 }
 181
 182 /* Returns made up soname if lib doesn't have explicit DT_SONAME.  */
 183
 184 char *
 185 implicit_soname (const char *lib, int flag)
 186 {
 187   char *soname = xstrdup (lib);
 188
 189   if ((flag & FLAG_TYPE_MASK) != FLAG_LIBC4)
 190     return soname;
 191
 192   /* Aout files don't have a soname, just return the name
 193      including the major number.  */
 194   char *major = strstr (soname, ".so.");
 195   if (major)
 196     {
 197       char *dot = strstr (major + 4, ".");
 198       if (dot)
 199         *dot = '\0';
 200     }
 201   return soname;
 202 }
 203
 204 /* Get architecture specific version of process_elf_file.  */
 205 #include <readelflib.c>