NetBSD-5.0.2/usr.bin/crunch/crunchide/crunchide.c
/* $NetBSD: crunchide.c,v 1.12 2004/08/24 12:25:26 wiz 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
*/
/*
* crunchide.c - tiptoes through an a.out symbol table, hiding all defined
* global symbols. Allows the user to supply a "keep list" of symbols
* that are not to be hidden. This program relies on the use of the
* linker's -dc flag to actually put global bss data into the file's
* bss segment (rather than leaving it as undefined "common" data).
*
* The point of all this is to allow multiple programs to be linked
* together without getting multiple-defined errors.
*
* For example, consider a program "foo.c". It can be linked with a
* small stub routine, called "foostub.c", eg:
* int foo_main(int argc, char **argv){ return main(argc, argv); }
* like so:
* cc -c foo.c foostub.c
* ld -dc -r foo.o foostub.o -o foo.combined.o
* crunchide -k _foo_main foo.combined.o
* at this point, foo.combined.o can be linked with another program
* and invoked with "foo_main(argc, argv)". foo's main() and any
* other globals are hidden and will not conflict with other symbols.
*
* TODO:
* - resolve the theoretical hanging reloc problem (see check_reloc()
* below). I have yet to see this problem actually occur in any real
* program. In what cases will gcc/gas generate code that needs a
* relative reloc from a global symbol, other than PIC? The
* solution is to not hide the symbol from the linker in this case,
* but to generate some random name for it so that it doesn't link
* with anything but holds the place for the reloc.
* - arrange that all the BSS segments start at the same address, so
* that the final crunched binary BSS size is the max of all the
* component programs' BSS sizes, rather than their sum.
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: crunchide.c,v 1.12 2004/08/24 12:25:26 wiz Exp $");
#endif
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <a.out.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "extern.h"
void usage(void);
void add_to_keep_list(char *symbol);
void add_file_to_keep_list(char *filename);
int hide_syms(const char *filename);
int verbose;
int
main(int argc, char *argv[])
{
int ch, errors;
setprogname(argv[0]);
while ((ch = getopt(argc, argv, "k:f:v")) != -1)
switch(ch) {
case 'k':
add_to_keep_list(optarg);
break;
case 'f':
add_file_to_keep_list(optarg);
break;
case 'v':
verbose = 1;
break;
default:
usage();
}
argc -= optind;
argv += optind;
if (argc == 0)
usage();
errors = 0;
while (argc) {
if (hide_syms(*argv))
errors = 1;
argc--, argv++;
}
return errors;
}
void
usage(void)
{
fprintf(stderr,
"Usage: %s [-k keep-symbol] [-f keep-list-file] object-file\n"
"\t\t [object-file ...]\n",
getprogname());
exit(1);
}
/* ---------------------------- */
struct keep {
struct keep *next;
char *sym;
} *keep_list;
void
add_to_keep_list(char *symbol)
{
struct keep *newp, *prevp, *curp;
int cmp;
cmp = 0;
for (curp = keep_list, prevp = NULL; curp; prevp = curp, curp = curp->next)
if ((cmp = strcmp(symbol, curp->sym)) <= 0)
break;
if (curp && cmp == 0)
return; /* already in table */
newp = (struct keep *) malloc(sizeof(struct keep));
if (newp)
newp->sym = strdup(symbol);
if (newp == NULL || newp->sym == NULL) {
fprintf(stderr, "%s: out of memory for keep list\n", getprogname());
exit(1);
}
newp->next = curp;
if (prevp)
prevp->next = newp;
else
keep_list = newp;
}
int
in_keep_list(const char *symbol)
{
struct keep *curp;
int cmp;
cmp = 0;
for (curp = keep_list; curp; curp = curp->next)
if((cmp = strcmp(symbol, curp->sym)) <= 0)
break;
return curp && cmp == 0;
}
void
add_file_to_keep_list(char *filename)
{
FILE *keepf;
char symbol[1024];
int len;
if ((keepf = fopen(filename, "r")) == NULL) {
perror(filename);
usage();
}
while (fgets(symbol, 1024, keepf)) {
len = strlen(symbol);
if (len && symbol[len-1] == '\n')
symbol[len-1] = '\0';
add_to_keep_list(symbol);
}
fclose(keepf);
}
/* ---------------------------- */
struct {
const char *name;
int (*check)(int, const char *); /* 1 if match, zero if not */
int (*hide)(int, const char *); /* non-zero if error */
} exec_formats[] = {
#ifdef NLIST_AOUT
{ "a.out", check_aout, hide_aout, },
#endif
#ifdef NLIST_COFF
{ "COFF", check_coff, hide_coff, },
#endif
#ifdef NLIST_ECOFF
{ "ECOFF", check_ecoff, hide_ecoff, },
#endif
#ifdef NLIST_ELF32
{ "ELF32", check_elf32, hide_elf32, },
#endif
#ifdef NLIST_ELF64
{ "ELF64", check_elf64, hide_elf64, },
#endif
};
int
hide_syms(const char *filename)
{
int fd, i, n, rv;
fd = open(filename, O_RDWR, 0);
if (fd == -1) {
perror(filename);
return 1;
}
rv = 0;
n = sizeof exec_formats / sizeof exec_formats[0];
for (i = 0; i < n; i++) {
if (lseek(fd, 0, SEEK_SET) != 0) {
perror(filename);
goto err;
}
if ((*exec_formats[i].check)(fd, filename) != 0)
break;
}
if (i == n) {
fprintf(stderr, "%s: unknown executable format\n", filename);
goto err;
}
if (verbose)
fprintf(stderr, "%s is an %s binary\n", filename,
exec_formats[i].name);
if (lseek(fd, 0, SEEK_SET) != 0) {
perror(filename);
goto err;
}
rv = (*exec_formats[i].hide)(fd, filename);
out:
close(fd);
return rv;
err:
rv = 1;
goto out;
}