mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-25 11:37:56 +00:00
315 lines
8.8 KiB
C
315 lines
8.8 KiB
C
/*
|
|
* 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 <a.out.h>
|
|
#include <err.h>
|
|
#include <fcntl.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/errno.h>
|
|
|
|
void usage(void);
|
|
|
|
void add_to_keep_list(char *symbol);
|
|
void add_file_to_keep_list(char *filename);
|
|
|
|
void hide_syms(char *filename);
|
|
|
|
|
|
int main(argc, argv)
|
|
int argc;
|
|
char **argv;
|
|
{
|
|
int ch;
|
|
|
|
while ((ch = getopt(argc, argv, "k:f:")) != -1)
|
|
switch(ch) {
|
|
case 'k':
|
|
add_to_keep_list(optarg);
|
|
break;
|
|
case 'f':
|
|
add_file_to_keep_list(optarg);
|
|
break;
|
|
default:
|
|
usage();
|
|
}
|
|
|
|
argc -= optind;
|
|
argv += optind;
|
|
|
|
if(argc == 0) usage();
|
|
|
|
while(argc) {
|
|
hide_syms(*argv);
|
|
argc--, argv++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void usage(void)
|
|
{
|
|
fprintf(stderr,
|
|
"usage: crunchide [-k <symbol-name>] [-f <keep-list-file>] <files> ...\n");
|
|
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;
|
|
|
|
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) {
|
|
errx(1, "out of memory for keep list");
|
|
}
|
|
|
|
newp->next = curp;
|
|
if(prevp) prevp->next = newp;
|
|
else keep_list = newp;
|
|
}
|
|
|
|
int in_keep_list(char *symbol)
|
|
{
|
|
struct keep *curp;
|
|
int cmp;
|
|
|
|
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) {
|
|
warn("%s", 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);
|
|
}
|
|
|
|
/* ---------------------- */
|
|
|
|
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)
|
|
|
|
void check_reloc(char *filename, struct relocation_info *relp);
|
|
|
|
void hide_syms(char *filename)
|
|
{
|
|
int inf, rc;
|
|
struct stat infstat;
|
|
struct relocation_info *relp;
|
|
struct nlist *symp;
|
|
|
|
/*
|
|
* Open the file and do some error checking.
|
|
*/
|
|
|
|
if((inf = open(filename, O_RDWR)) == -1) {
|
|
warn("%s", filename);
|
|
return;
|
|
}
|
|
|
|
if(fstat(inf, &infstat) == -1) {
|
|
warn("%s", filename);
|
|
close(inf);
|
|
return;
|
|
}
|
|
|
|
if(infstat.st_size < sizeof(struct exec)) {
|
|
warnx("%s: short file", filename);
|
|
close(inf);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* 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) {
|
|
warnx("%s: too big to read into memory", filename);
|
|
close(inf);
|
|
return;
|
|
}
|
|
|
|
if((rc = read(inf, aoutdata, infstat.st_size)) < infstat.st_size) {
|
|
warnx("%s: read error: %s", filename,
|
|
rc == -1? strerror(errno) : "short read");
|
|
close(inf);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Check the header and calculate offsets and sizes from it.
|
|
*/
|
|
|
|
hdrp = (struct exec *) aoutdata;
|
|
|
|
if(N_BADMAG(*hdrp)) {
|
|
warnx("%s: bad magic: not an a.out file", filename);
|
|
close(inf);
|
|
return;
|
|
}
|
|
|
|
#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) && !in_keep_list(SYMSTR(symp)))
|
|
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) {
|
|
warnx("%s: write error: %s", filename,
|
|
rc == -1? strerror(errno) : "short write");
|
|
}
|
|
|
|
close(inf);
|
|
}
|
|
|
|
|
|
void check_reloc(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) {
|
|
errx(1, "%s: oops, have hanging relocation for %s: bailing out!",
|
|
filename, SYMSTR(&symbase[relp->r_symbolnum]));
|
|
}
|
|
}
|