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;
}
void
hide_syms(char *filename)
{
int inf, outf, rc;
struct stat infstat;
struct relocation_info *relp;
struct nlist *symp;
char *buf;
u_char zero = 0;
/*
* Open the file and do some error checking.
*/
if ((inf = open(filename, O_RDWR)) == -1) {
perror(filename);
return;
}
if (fstat(inf, &infstat) == -1) {
perror(filename);
close(inf);
return;
}
if (infstat.st_size < sizeof(struct exec)) {
fprintf(stderr, "%s: short file\n", filename);
close(inf);
return;
}
if ((buf = mmap(NULL, infstat.st_size, PROT_READ | PROT_WRITE,
MAP_FILE | MAP_SHARED, inf, 0)) == MAP_FAILED) {
fprintf(stderr, "%s: cannot map\n", filename);
close(inf);
return;
}
#ifdef _NLIST_DO_ELF
if (buf[0] == 0x7f && (buf[1] == 'E' || buf[1] == 'O') &&
buf[2] == 'L' && buf[3] == 'F') {
elf_hide(inf, buf);
return;
}
#endif /* _NLIST_DO_ELF */
#ifdef _NLIST_DO_ECOFF
if (!ECOFF_BADMAG((struct ecoff_exechdr *) buf)) {
ecoff_hide(inf, buf);
return;
}
#endif /* _NLIST_DO_ECOFF */
#ifdef DO_AOUT
aoutdata = buf;
/*
* Check the header and calculate offsets and sizes from it.
*/
hdrp = (struct exec *) aoutdata;
if (N_BADMAG(*hdrp)) {
fprintf(stderr, "%s: bad magic: not an a.out, ecoff or elf file\n",
filename);
close(inf);
return;
}
textrel = (struct relocation_info *) (aoutdata + N_TRELOFF(*hdrp));
datarel = (struct relocation_info *) (aoutdata + N_DRELOFF(*hdrp));
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))) {
/*
* XXX Our VM system has some problems, so
* avoid the VM system....
*/
lseek(inf, (off_t) ((void *) &symp->n_type -
(void *) buf), SEEK_SET);
write(inf, &zero, sizeof zero);
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);
msync(buf, infstat.st_size, MS_SYNC);
munmap(buf, infstat.st_size);
close(inf);
#endif /* DO_AOUT */
}
