/*      $NetBSD: crunchide.c,v 1.8 1997/11/01 06:51:45 lukem 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 a symbol table, hiding all defined
 *      global symbols.  Allows the user to supply a "keep list" of symbols
 *      that are not to be hidden.
 *
 *      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 -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 1.8 1997/11/01 06:51:45 lukem Exp $");
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/errno.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>

#include "extern.h"

static const char *pname = "crunchide";

static void usage(void) __dead2;

static void add_to_keep_list(char *symbol);
static void add_file_to_keep_list(char *filename);

static int hide_syms(const char *filename);

static int verbose;

int main(int, char *[]);

int
main(int argc, char **argv)
{
    int ch, errors;

    if(argc > 0) pname = 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;
}

static void
usage(void)
{
    fprintf(stderr,
            "usage: %s [-k <symbol-name>] [-f <keep-list-file>] <files> ...\n",
            pname);
    exit(1);
}

/* ---------------------------- */

static struct keep {
    struct keep *next;
    char *sym;
} *keep_list;

static 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", pname);
        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;
}

static 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, sizeof(symbol), keepf)) {
        len = strlen(symbol);
        if(len && symbol[len-1] == '\n')
            symbol[len-1] = '\0';

        add_to_keep_list(symbol);
    }
    fclose(keepf);
}

/* ---------------------------- */

static 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_ELF32
        {       "ELF32",        check_elf32,    hide_elf32,     },
#endif
#ifdef NLIST_ELF64
        {       "ELF64",        check_elf64,    hide_elf64,     },
#endif
};

static 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;
}