usr.bin/crunch/crunchide/exec_aout.c

   1 /*      $NetBSD: exec_aout.c,v 1.6 1997/08/02 21:30:17 perry Exp $      */
   2 /*
   3  * Copyright (c) 1997 Christopher G. Demetriou.  All rights reserved.
   4  * Copyright (c) 1994 University of Maryland
   5  * All Rights Reserved.
   6  *
   7  * Permission to use, copy, modify, distribute, and sell this software and its
   8  * documentation for any purpose is hereby granted without fee, provided that
   9  * the above copyright notice appear in all copies and that both that
  10  * copyright notice and this permission notice appear in supporting
  11  * documentation, and that the name of U.M. not be used in advertising or
  12  * publicity pertaining to distribution of the software without specific,
  13  * written prior permission.  U.M. makes no representations about the
  14  * suitability of this software for any purpose.  It is provided "as is"
  15  * without express or implied warranty.
  16  *
  17  * U.M. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL U.M.
  19  * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  20  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  21  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  22  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  23  *
  24  * Author: James da Silva, Systems Design and Analysis Group
  25  *                         Computer Science Department
  26  *                         University of Maryland at College Park
  27  *
  28  * $NetBSD: exec_aout.c,v 1.6 1997/08/02 21:30:17 perry Exp $
  29  * $FreeBSD: src/usr.sbin/crunch/crunchide/exec_aout.c,v 1.1.6.1 2002/07/25 09:33:17 ru Exp $
  30  * $DragonFly: src/usr.sbin/crunch/crunchide/exec_aout.c,v 1.5 2004/02/08 10:48:30 rob Exp $
  31  */
  32 #include <sys/cdefs.h>
  33
  34 #include <unistd.h>
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <a.out.h>
  39 #include <sys/types.h>
  40 #include <sys/stat.h>
  41 #include <sys/errno.h>
  42
  43 #include "extern.h"
  44
  45 #if defined(NLIST_AOUT)
  46
  47 int nsyms, ntextrel, ndatarel;
  48 struct exec *hdrp;
  49 char *aoutdata, *strbase;
  50 struct relocation_info *textrel, *datarel;
  51 struct nlist *symbase;
  52
  53
  54 #define SYMSTR(sp)      (&strbase[(sp)->n_un.n_strx])
  55
  56 /* is the symbol a global symbol defined in the current file? */
  57 #define IS_GLOBAL_DEFINED(sp) \
  58                   (((sp)->n_type & N_EXT) && ((sp)->n_type & N_TYPE) != N_UNDF)
  59
  60 #ifdef arch_sparc
  61 /* is the relocation entry dependent on a symbol? */
  62 #define IS_SYMBOL_RELOC(rp)   \
  63         ((rp)->r_extern || \
  64         ((rp)->r_type >= RELOC_BASE10 && (rp)->r_type <= RELOC_BASE22) || \
  65         (rp)->r_type == RELOC_JMP_TBL)
  66 #else
  67 /* is the relocation entry dependent on a symbol? */
  68 #define IS_SYMBOL_RELOC(rp)   \
  69                   ((rp)->r_extern||(rp)->r_baserel||(rp)->r_jmptable)
  70 #endif
  71
  72 static void check_reloc(const char *filename, struct relocation_info *relp);
  73
  74 int
  75 check_aout(int inf, const char *filename)
  76 {
  77     struct stat infstat;
  78     struct exec eh;
  79
  80     /*
  81      * check the header to make sure it's an a.out-format file.
  82      */
  83
  84     if(fstat(inf, &infstat) == -1)
  85         return 0;
  86     if(infstat.st_size < sizeof eh)
  87         return 0;
  88     if(read(inf, &eh, sizeof eh) != sizeof eh)
  89         return 0;
  90
  91     if(N_BADMAG(eh))
  92         return 0;
  93
  94     return 1;
  95 }
  96
  97 int
  98 hide_aout(int inf, const char *filename)
  99 {
 100     struct stat infstat;
 101     struct relocation_info *relp;
 102     struct nlist *symp;
 103     int rc;
 104
 105     /*
 106      * do some error checking.
 107      */
 108
 109     if(fstat(inf, &infstat) == -1) {
 110         perror(filename);
 111         return 1;
 112     }
 113
 114     /*
 115      * Read the entire file into memory.  XXX - Really, we only need to
 116      * read the header and from TRELOFF to the end of the file.
 117      */
 118
 119     if((aoutdata = (char *) malloc(infstat.st_size)) == NULL) {
 120         fprintf(stderr, "%s: too big to read into memory\n", filename);
 121         return 1;
 122     }
 123
 124     if((rc = read(inf, aoutdata, infstat.st_size)) < infstat.st_size) {
 125         fprintf(stderr, "%s: read error: %s\n", filename,
 126                 rc == -1? strerror(errno) : "short read");
 127         return 1;
 128     }
 129
 130     /*
 131      * Calculate offsets and sizes from the header.
 132      */
 133
 134     hdrp = (struct exec *) aoutdata;
 135
 136 #if defined  (__DragonFly__) || defined (__FreeBSD__)
 137     textrel = (struct relocation_info *) (aoutdata + N_RELOFF(*hdrp));
 138     datarel = (struct relocation_info *) (aoutdata + N_RELOFF(*hdrp) +
 139                                           hdrp->a_trsize);
 140 #else
 141     textrel = (struct relocation_info *) (aoutdata + N_TRELOFF(*hdrp));
 142     datarel = (struct relocation_info *) (aoutdata + N_DRELOFF(*hdrp));
 143 #endif
 144     symbase = (struct nlist *)           (aoutdata + N_SYMOFF(*hdrp));
 145     strbase = (char *)                   (aoutdata + N_STROFF(*hdrp));
 146
 147     ntextrel = hdrp->a_trsize / sizeof(struct relocation_info);
 148     ndatarel = hdrp->a_drsize / sizeof(struct relocation_info);
 149     nsyms    = hdrp->a_syms   / sizeof(struct nlist);
 150
 151     /*
 152      * Zap the type field of all globally-defined symbols.  The linker will
 153      * subsequently ignore these entries.  Don't zap any symbols in the
 154      * keep list.
 155      */
 156
 157     for(symp = symbase; symp < symbase + nsyms; symp++) {
 158         if(!IS_GLOBAL_DEFINED(symp))            /* keep undefined syms */
 159             continue;
 160
 161         /* keep (C) symbols which are on the keep list */
 162         if(SYMSTR(symp)[0] == '_' && in_keep_list(SYMSTR(symp) + 1))
 163             continue;
 164
 165         symp->n_type = 0;
 166     }
 167
 168     /*
 169      * Check whether the relocation entries reference any symbols that we
 170      * just zapped.  I don't know whether ld can handle this case, but I
 171      * haven't encountered it yet.  These checks are here so that the program
 172      * doesn't fail silently should such symbols be encountered.
 173      */
 174
 175     for(relp = textrel; relp < textrel + ntextrel; relp++)
 176         check_reloc(filename, relp);
 177     for(relp = datarel; relp < datarel + ndatarel; relp++)
 178         check_reloc(filename, relp);
 179
 180     /*
 181      * Write the .o file back out to disk.  XXX - Really, we only need to
 182      * write the symbol table entries back out.
 183      */
 184     lseek(inf, 0, SEEK_SET);
 185     if((rc = write(inf, aoutdata, infstat.st_size)) < infstat.st_size) {
 186         fprintf(stderr, "%s: write error: %s\n", filename,
 187                 rc == -1? strerror(errno) : "short write");
 188         return 1;
 189     }
 190
 191     return 0;
 192 }
 193
 194
 195 static void
 196 check_reloc(const char *filename, struct relocation_info *relp)
 197 {
 198     /* bail out if we zapped a symbol that is needed */
 199     if(IS_SYMBOL_RELOC(relp) && symbase[relp->r_symbolnum].n_type == 0) {
 200         fprintf(stderr,
 201                 "%s: oops, have hanging relocation for %s: bailing out!\n",
 202                 filename, SYMSTR(&symbase[relp->r_symbolnum]));
 203         exit(1);
 204     }
 205 }
 206
 207 #endif /* defined(NLIST_AOUT) */