/* $NetBSD: exec_aout.c,v 1.12 2009/08/20 17:40:26 he 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 */ #include #ifndef lint __RCSID("$NetBSD: exec_aout.c,v 1.12 2009/08/20 17:40:26 he Exp $"); #endif #include #include #include #include #include #include #include #include "extern.h" #if defined(NLIST_AOUT) #include #include 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) #ifdef __sparc__ /* is the relocation entry dependent on a symbol? */ #define IS_SYMBOL_RELOC(rp) \ ((rp)->r_extern || \ ((rp)->r_type >= RELOC_BASE10 && (rp)->r_type <= RELOC_BASE22) || \ (rp)->r_type == RELOC_JMP_TBL) #else /* is the relocation entry dependent on a symbol? */ #define IS_SYMBOL_RELOC(rp) \ ((rp)->r_extern||(rp)->r_baserel||(rp)->r_jmptable) #endif static void check_reloc(const char *filename, struct relocation_info *relp); int check_aout(int inf, const char *filename) { struct stat infstat; struct exec eh; /* * check the header to make sure it's an a.out-format file. */ if(fstat(inf, &infstat) == -1) return 0; if(infstat.st_size < (ssize_t)sizeof eh) return 0; if(read(inf, &eh, sizeof eh) != sizeof eh) return 0; if(N_BADMAG(eh)) return 0; return 1; } 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; } static void check_reloc(const 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) { fprintf(stderr, "%s: oops, have hanging relocation for %s: bailing out!\n", filename, SYMSTR(&symbase[relp->r_symbolnum])); exit(1); } } #endif /* defined(NLIST_AOUT) */