204 lines
6.1 KiB
C
204 lines
6.1 KiB
C
/* $NetBSD: exec_aout.c,v 1.6 1997/08/02 21:30:17 perry Exp $ */
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/*
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* Copyright (c) 1997 Christopher G. Demetriou. All rights reserved.
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* Copyright (c) 1994 University of Maryland
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* All Rights Reserved.
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*
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* Permission to use, copy, modify, distribute, and sell this software and its
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* documentation for any purpose is hereby granted without fee, provided that
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* the above copyright notice appear in all copies and that both that
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* copyright notice and this permission notice appear in supporting
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* documentation, and that the name of U.M. not be used in advertising or
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* publicity pertaining to distribution of the software without specific,
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* written prior permission. U.M. makes no representations about the
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* suitability of this software for any purpose. It is provided "as is"
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* without express or implied warranty.
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*
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* U.M. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL U.M.
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* BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* Author: James da Silva, Systems Design and Analysis Group
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* Computer Science Department
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* University of Maryland at College Park
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__RCSID("$NetBSD: exec_aout.c,v 1.6 1997/08/02 21:30:17 perry Exp $");
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#endif
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <a.out.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/errno.h>
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#include "extern.h"
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#if defined(NLIST_AOUT)
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int nsyms, ntextrel, ndatarel;
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struct exec *hdrp;
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char *aoutdata, *strbase;
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struct relocation_info *textrel, *datarel;
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struct nlist *symbase;
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#define SYMSTR(sp) (&strbase[(sp)->n_un.n_strx])
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/* is the symbol a global symbol defined in the current file? */
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#define IS_GLOBAL_DEFINED(sp) \
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(((sp)->n_type & N_EXT) && ((sp)->n_type & N_TYPE) != N_UNDF)
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#ifdef __sparc
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/* is the relocation entry dependent on a symbol? */
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#define IS_SYMBOL_RELOC(rp) \
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((rp)->r_extern || \
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((rp)->r_type >= RELOC_BASE10 && (rp)->r_type <= RELOC_BASE22) || \
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(rp)->r_type == RELOC_JMP_TBL)
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#else
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/* is the relocation entry dependent on a symbol? */
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#define IS_SYMBOL_RELOC(rp) \
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((rp)->r_extern||(rp)->r_baserel||(rp)->r_jmptable)
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#endif
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static void check_reloc(const char *filename, struct relocation_info *relp);
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int check_aout(int inf, const char *filename)
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{
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struct stat infstat;
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struct exec eh;
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/*
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* check the header to make sure it's an a.out-format file.
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*/
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if(fstat(inf, &infstat) == -1)
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return 0;
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if(infstat.st_size < sizeof eh)
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return 0;
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if(read(inf, &eh, sizeof eh) != sizeof eh)
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return 0;
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if(N_BADMAG(eh))
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return 0;
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return 1;
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}
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int hide_aout(int inf, const char *filename)
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{
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struct stat infstat;
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struct relocation_info *relp;
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struct nlist *symp;
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int rc;
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/*
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* do some error checking.
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*/
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if(fstat(inf, &infstat) == -1) {
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perror(filename);
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return 1;
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}
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/*
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* Read the entire file into memory. XXX - Really, we only need to
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* read the header and from TRELOFF to the end of the file.
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*/
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if((aoutdata = (char *) malloc(infstat.st_size)) == NULL) {
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fprintf(stderr, "%s: too big to read into memory\n", filename);
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return 1;
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}
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if((rc = read(inf, aoutdata, infstat.st_size)) < infstat.st_size) {
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fprintf(stderr, "%s: read error: %s\n", filename,
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rc == -1? strerror(errno) : "short read");
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return 1;
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}
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/*
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* Calculate offsets and sizes from the header.
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*/
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hdrp = (struct exec *) aoutdata;
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#ifdef __FreeBSD__
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textrel = (struct relocation_info *) (aoutdata + N_RELOFF(*hdrp));
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datarel = (struct relocation_info *) (aoutdata + N_RELOFF(*hdrp) +
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hdrp->a_trsize);
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#else
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textrel = (struct relocation_info *) (aoutdata + N_TRELOFF(*hdrp));
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datarel = (struct relocation_info *) (aoutdata + N_DRELOFF(*hdrp));
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#endif
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symbase = (struct nlist *) (aoutdata + N_SYMOFF(*hdrp));
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strbase = (char *) (aoutdata + N_STROFF(*hdrp));
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ntextrel = hdrp->a_trsize / sizeof(struct relocation_info);
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ndatarel = hdrp->a_drsize / sizeof(struct relocation_info);
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nsyms = hdrp->a_syms / sizeof(struct nlist);
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/*
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* Zap the type field of all globally-defined symbols. The linker will
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* subsequently ignore these entries. Don't zap any symbols in the
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* keep list.
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*/
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for(symp = symbase; symp < symbase + nsyms; symp++) {
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if(!IS_GLOBAL_DEFINED(symp)) /* keep undefined syms */
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continue;
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/* keep (C) symbols which are on the keep list */
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if(SYMSTR(symp)[0] == '_' && in_keep_list(SYMSTR(symp) + 1))
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continue;
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symp->n_type = 0;
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}
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/*
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* Check whether the relocation entries reference any symbols that we
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* just zapped. I don't know whether ld can handle this case, but I
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* haven't encountered it yet. These checks are here so that the program
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* doesn't fail silently should such symbols be encountered.
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*/
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for(relp = textrel; relp < textrel + ntextrel; relp++)
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check_reloc(filename, relp);
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for(relp = datarel; relp < datarel + ndatarel; relp++)
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check_reloc(filename, relp);
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/*
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* Write the .o file back out to disk. XXX - Really, we only need to
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* write the symbol table entries back out.
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*/
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lseek(inf, 0, SEEK_SET);
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if((rc = write(inf, aoutdata, infstat.st_size)) < infstat.st_size) {
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fprintf(stderr, "%s: write error: %s\n", filename,
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rc == -1? strerror(errno) : "short write");
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return 1;
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}
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return 0;
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}
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static void check_reloc(const char *filename, struct relocation_info *relp)
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{
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/* bail out if we zapped a symbol that is needed */
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if(IS_SYMBOL_RELOC(relp) && symbase[relp->r_symbolnum].n_type == 0) {
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fprintf(stderr,
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"%s: oops, have hanging relocation for %s: bailing out!\n",
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filename, SYMSTR(&symbase[relp->r_symbolnum]));
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exit(1);
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}
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}
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#endif /* defined(NLIST_AOUT) */
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