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268 lines
6.7 KiB
C
268 lines
6.7 KiB
C
/* $NetBSD: crunchide.c,v 1.8 1997/11/01 06:51:45 lukem 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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/*
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* crunchide.c - tiptoes through an a.out symbol table, hiding all defined
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* global symbols. Allows the user to supply a "keep list" of symbols
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* that are not to be hidden. This program relies on the use of the
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* linker's -dc flag to actually put global bss data into the file's
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* bss segment (rather than leaving it as undefined "common" data).
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*
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* The point of all this is to allow multiple programs to be linked
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* together without getting multiple-defined errors.
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*
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* For example, consider a program "foo.c". It can be linked with a
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* small stub routine, called "foostub.c", eg:
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* int foo_main(int argc, char **argv){ return main(argc, argv); }
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* like so:
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* cc -c foo.c foostub.c
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* ld -dc -r foo.o foostub.o -o foo.combined.o
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* crunchide -k _foo_main foo.combined.o
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* at this point, foo.combined.o can be linked with another program
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* and invoked with "foo_main(argc, argv)". foo's main() and any
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* other globals are hidden and will not conflict with other symbols.
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*
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* TODO:
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* - resolve the theoretical hanging reloc problem (see check_reloc()
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* below). I have yet to see this problem actually occur in any real
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* program. In what cases will gcc/gas generate code that needs a
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* relative reloc from a global symbol, other than PIC? The
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* solution is to not hide the symbol from the linker in this case,
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* but to generate some random name for it so that it doesn't link
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* with anything but holds the place for the reloc.
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* - arrange that all the BSS segments start at the same address, so
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* that the final crunched binary BSS size is the max of all the
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* component programs' BSS sizes, rather than their sum.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__RCSID("$NetBSD: crunchide.c,v 1.8 1997/11/01 06:51:45 lukem 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 <fcntl.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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char *pname = "crunchide";
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void usage(void);
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void add_to_keep_list(char *symbol);
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void add_file_to_keep_list(char *filename);
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int hide_syms(const char *filename);
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int verbose;
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int main __P((int, char *[]));
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int main(argc, argv)
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int argc;
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char **argv;
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{
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int ch, errors;
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if(argc > 0) pname = argv[0];
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while ((ch = getopt(argc, argv, "k:f:v")) != -1)
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switch(ch) {
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case 'k':
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add_to_keep_list(optarg);
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break;
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case 'f':
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add_file_to_keep_list(optarg);
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break;
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case 'v':
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verbose = 1;
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break;
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default:
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usage();
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}
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argc -= optind;
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argv += optind;
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if(argc == 0) usage();
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errors = 0;
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while(argc) {
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if (hide_syms(*argv))
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errors = 1;
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argc--, argv++;
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}
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return errors;
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}
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void usage(void)
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{
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fprintf(stderr,
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"Usage: %s [-k <symbol-name>] [-f <keep-list-file>] <files> ...\n",
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pname);
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exit(1);
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}
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/* ---------------------------- */
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struct keep {
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struct keep *next;
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char *sym;
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} *keep_list;
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void add_to_keep_list(char *symbol)
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{
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struct keep *newp, *prevp, *curp;
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int cmp;
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cmp = 0;
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for(curp = keep_list, prevp = NULL; curp; prevp = curp, curp = curp->next)
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if((cmp = strcmp(symbol, curp->sym)) <= 0) break;
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if(curp && cmp == 0)
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return; /* already in table */
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newp = (struct keep *) malloc(sizeof(struct keep));
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if(newp) newp->sym = strdup(symbol);
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if(newp == NULL || newp->sym == NULL) {
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fprintf(stderr, "%s: out of memory for keep list\n", pname);
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exit(1);
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}
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newp->next = curp;
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if(prevp) prevp->next = newp;
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else keep_list = newp;
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}
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int in_keep_list(const char *symbol)
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{
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struct keep *curp;
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int cmp;
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cmp = 0;
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for(curp = keep_list; curp; curp = curp->next)
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if((cmp = strcmp(symbol, curp->sym)) <= 0) break;
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return curp && cmp == 0;
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}
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void add_file_to_keep_list(char *filename)
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{
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FILE *keepf;
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char symbol[1024];
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int len;
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if((keepf = fopen(filename, "r")) == NULL) {
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perror(filename);
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usage();
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}
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while(fgets(symbol, 1024, keepf)) {
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len = strlen(symbol);
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if(len && symbol[len-1] == '\n')
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symbol[len-1] = '\0';
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add_to_keep_list(symbol);
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}
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fclose(keepf);
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}
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/* ---------------------------- */
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struct {
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const char *name;
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int (*check)(int, const char *); /* 1 if match, zero if not */
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int (*hide)(int, const char *); /* non-zero if error */
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} exec_formats[] = {
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#ifdef NLIST_AOUT
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{ "a.out", check_aout, hide_aout, },
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#endif
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#ifdef NLIST_ECOFF
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{ "ECOFF", check_elf64, hide_elf64, },
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#endif
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#ifdef NLIST_ELF32
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{ "ELF32", check_elf32, hide_elf32, },
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#endif
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#ifdef NLIST_ELF64
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{ "ELF64", check_elf64, hide_elf64, },
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#endif
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};
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int hide_syms(const char *filename)
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{
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int fd, i, n, rv;
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fd = open(filename, O_RDWR, 0);
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if (fd == -1) {
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perror(filename);
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return 1;
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}
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rv = 0;
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n = sizeof exec_formats / sizeof exec_formats[0];
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for (i = 0; i < n; i++) {
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if (lseek(fd, 0, SEEK_SET) != 0) {
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perror(filename);
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goto err;
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}
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if ((*exec_formats[i].check)(fd, filename) != 0)
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break;
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}
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if (i == n) {
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fprintf(stderr, "%s: unknown executable format\n", filename);
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goto err;
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}
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if (verbose)
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fprintf(stderr, "%s is an %s binary\n", filename,
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exec_formats[i].name);
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if (lseek(fd, 0, SEEK_SET) != 0) {
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perror(filename);
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goto err;
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}
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rv = (*exec_formats[i].hide)(fd, filename);
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out:
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close (fd);
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return (rv);
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err:
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rv = 1;
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goto out;
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}
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