elf/readlib.c

   1 /* Copyright (C) 1999 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 <a.out.h>
  28 #include <elf.h>
  29 #include <error.h>
  30 #include <link.h>
  31 #include <libintl.h>
  32 #include <stdio.h>
  33 #include <string.h>
  34 #include <unistd.h>
  35
  36 #include <sys/mman.h>
  37 #include <sys/stat.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-linux.so.2", FLAG_ELF_LIBC6},
  53   {"/lib/ld-linux.so.1", FLAG_ELF_LIBC5}
  54 };
  55
  56 static struct known_names known_libs [] =
  57 {
  58   {"libc.so.6", FLAG_ELF_LIBC6},
  59   {"libc.so.5", FLAG_ELF_LIBC5},
  60   {"libm.so.6", FLAG_ELF_LIBC6},
  61   {"libm.so.5", FLAG_ELF_LIBC5}
  62 };
  63
  64
  65
  66 /* Returns 0 if everything is ok, != 0 in case of error.  */
  67 int
  68 process_file (const char *file_name, const char *lib, int *flag, char **soname, int is_link)
  69 {
  70   FILE *file;
  71   struct stat statbuf;
  72   void *file_contents;
  73   int ret;
  74
  75   ElfW(Ehdr) *elf_header;
  76   struct exec *aout_header;
  77
  78   ret = 0;
  79   *flag = FLAG_ANY;
  80   *soname = NULL;
  81
  82   file = fopen (file_name, "rb");
  83   if (file == NULL)
  84     {
  85       /* No error for stale symlink.  */
  86       if (is_link && strstr (file_name, ".so.") != NULL)
  87         return 1;
  88       error (0, 0, _("Input file %s not found.\n"), file_name);
  89       return 1;
  90     }
  91
  92   if (fstat (fileno (file), &statbuf) < 0)
  93     {
  94       error (0, 0, _("Cannot fstat file %s.\n"), file_name);
  95       return 1;
  96     }
  97
  98   file_contents = mmap (0, statbuf.st_size, PROT_READ, MAP_SHARED, fileno (file), 0);
  99   if (file_contents == MAP_FAILED)
 100     {
 101       error (0, 0, _("Cannot mmap file %s.\n"), file_name);
 102       fclose (file);
 103       return 1;
 104     }
 105
 106   /* First check if this is an aout file.  */
 107   aout_header = (struct exec *) file_contents;
 108   if (N_MAGIC (*aout_header) == ZMAGIC
 109       || N_MAGIC (*aout_header) == QMAGIC)
 110     {
 111       /* Aout files don't have a soname, just return the the name
 112          including the major number.  */
 113       char *copy, *major, *dot;
 114       copy = xstrdup (lib);
 115       major = strstr (copy, ".so.");
 116       if (major)
 117         {
 118           dot = strstr (major + 4, ".");
 119           if (dot)
 120             *dot = '\0';
 121         }
 122       *soname = copy;
 123       *flag = FLAG_LIBC4;
 124       goto done;
 125     }
 126
 127   elf_header = (ElfW(Ehdr) *) file_contents;
 128   if (elf_header->e_ident [EI_MAG0] != ELFMAG0
 129       || elf_header->e_ident [EI_MAG1] != ELFMAG1
 130       || elf_header->e_ident [EI_MAG2] != ELFMAG2
 131       || elf_header->e_ident [EI_MAG3] != ELFMAG3)
 132     {
 133       /* The file is neither ELF nor aout.  Check if it's a linker script,
 134          like libc.so - otherwise complain.  */
 135       int len = statbuf.st_size;
 136       /* Only search the beginning of the file.  */
 137       if (len > 512)
 138         len = 512;
 139       if (memmem (file_contents, len, "GROUP", 5) == NULL
 140           && memmem (file_contents, len, "GNU ld script", 13) == NULL)
 141         error (0, 0, _("%s is not an ELF file - it has the wrong magic bytes at the start.\n"),
 142                file_name);
 143       ret = 1;
 144       goto done;
 145     }
 146
 147   if (process_elf_file (file_name, lib, flag, soname, file_contents))
 148     ret = 1;
 149
 150  done:
 151   /* Clean up allocated memory and resources.  */
 152   munmap (file_contents, statbuf.st_size);
 153   fclose (file);
 154
 155   return ret;
 156 }
 157
 158 /* Get architecture specific version of process_elf_file.  */
 159 #include "readelflib.c"
 160