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       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 #ifdef QMAGIC                   /* Linuxism.  */
 126       || N_MAGIC (*aout_header) == QMAGIC
 127 #endif
 128       )
 129     {
 130       /* Aout files don't have a soname, just return the name
 131          including the major number.  */
 132       char *copy, *major, *dot;
 133       copy = xstrdup (lib);
 134       major = strstr (copy, ".so.");
 135       if (major)
 136         {
 137           dot = strstr (major + 4, ".");
 138           if (dot)
 139             *dot = '\0';
 140         }
 141       *soname = copy;
 142       *flag = FLAG_LIBC4;
 143       goto done;
 144     }
 145
 146   elf_header = (ElfW(Ehdr) *) file_contents;
 147   if (memcmp (elf_header->e_ident, ELFMAG, SELFMAG) != 0)
 148     {
 149       /* The file is neither ELF nor aout.  Check if it's a linker
 150          script, like libc.so - otherwise complain.  Only search the
 151          beginning of the file.  */
 152       size_t len = MIN (statbuf.st_size, 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     }
 159   /* Libraries have to be shared object files.  */
 160   else if (elf_header->e_type != ET_DYN)
 161     ret = 1;
 162   else if (process_elf_file (file_name, lib, flag, osversion, soname,
 163                              file_contents, statbuf.st_size))
 164     ret = 1;
 165
 166  done:
 167   /* Clean up allocated memory and resources.  */
 168   munmap (file_contents, statbuf.st_size);
 169   fclose (file);
 170
 171   return ret;
 172 }
 173
 174 /* Get architecture specific version of process_elf_file.  */
 175 #include "readelflib.c"