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