1 /* $NetBSD: exec_aout.c,v 1.6 1997/08/02 21:30:17 perry Exp $ */
3 * Copyright (c) 1997 Christopher G. Demetriou. All rights reserved.
4 * Copyright (c) 1994 University of Maryland
7 * Permission to use, copy, modify, distribute, and sell this software and its
8 * documentation for any purpose is hereby granted without fee, provided that
9 * the above copyright notice appear in all copies and that both that
10 * copyright notice and this permission notice appear in supporting
11 * documentation, and that the name of U.M. not be used in advertising or
12 * publicity pertaining to distribution of the software without specific,
13 * written prior permission. U.M. makes no representations about the
14 * suitability of this software for any purpose. It is provided "as is"
15 * without express or implied warranty.
17 * U.M. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL U.M.
19 * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
20 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
21 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
22 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
24 * Author: James da Silva, Systems Design and Analysis Group
25 * Computer Science Department
26 * University of Maryland at College Park
28 #include <sys/cdefs.h>
30 __RCSID("$NetBSD: exec_aout.c,v 1.6 1997/08/02 21:30:17 perry Exp $");
31 __FBSDID("$FreeBSD: src/usr.sbin/crunch/crunchide/exec_aout.c,v 1.1.6.1 2002/07/25 09:33:17 ru Exp $");
39 #include <sys/types.h>
41 #include <sys/errno.h>
45 #if defined(NLIST_AOUT)
47 int nsyms, ntextrel, ndatarel;
49 char *aoutdata, *strbase;
50 struct relocation_info *textrel, *datarel;
51 struct nlist *symbase;
54 #define SYMSTR(sp) (&strbase[(sp)->n_un.n_strx])
56 /* is the symbol a global symbol defined in the current file? */
57 #define IS_GLOBAL_DEFINED(sp) \
58 (((sp)->n_type & N_EXT) && ((sp)->n_type & N_TYPE) != N_UNDF)
61 /* is the relocation entry dependent on a symbol? */
62 #define IS_SYMBOL_RELOC(rp) \
64 ((rp)->r_type >= RELOC_BASE10 && (rp)->r_type <= RELOC_BASE22) || \
65 (rp)->r_type == RELOC_JMP_TBL)
67 /* is the relocation entry dependent on a symbol? */
68 #define IS_SYMBOL_RELOC(rp) \
69 ((rp)->r_extern||(rp)->r_baserel||(rp)->r_jmptable)
72 static void check_reloc(const char *filename, struct relocation_info *relp);
74 int check_aout(int inf, const char *filename)
80 * check the header to make sure it's an a.out-format file.
83 if(fstat(inf, &infstat) == -1)
85 if(infstat.st_size < sizeof eh)
87 if(read(inf, &eh, sizeof eh) != sizeof eh)
96 int hide_aout(int inf, const char *filename)
99 struct relocation_info *relp;
104 * do some error checking.
107 if(fstat(inf, &infstat) == -1) {
113 * Read the entire file into memory. XXX - Really, we only need to
114 * read the header and from TRELOFF to the end of the file.
117 if((aoutdata = (char *) malloc(infstat.st_size)) == NULL) {
118 fprintf(stderr, "%s: too big to read into memory\n", filename);
122 if((rc = read(inf, aoutdata, infstat.st_size)) < infstat.st_size) {
123 fprintf(stderr, "%s: read error: %s\n", filename,
124 rc == -1? strerror(errno) : "short read");
129 * Calculate offsets and sizes from the header.
132 hdrp = (struct exec *) aoutdata;
135 textrel = (struct relocation_info *) (aoutdata + N_RELOFF(*hdrp));
136 datarel = (struct relocation_info *) (aoutdata + N_RELOFF(*hdrp) +
139 textrel = (struct relocation_info *) (aoutdata + N_TRELOFF(*hdrp));
140 datarel = (struct relocation_info *) (aoutdata + N_DRELOFF(*hdrp));
142 symbase = (struct nlist *) (aoutdata + N_SYMOFF(*hdrp));
143 strbase = (char *) (aoutdata + N_STROFF(*hdrp));
145 ntextrel = hdrp->a_trsize / sizeof(struct relocation_info);
146 ndatarel = hdrp->a_drsize / sizeof(struct relocation_info);
147 nsyms = hdrp->a_syms / sizeof(struct nlist);
150 * Zap the type field of all globally-defined symbols. The linker will
151 * subsequently ignore these entries. Don't zap any symbols in the
155 for(symp = symbase; symp < symbase + nsyms; symp++) {
156 if(!IS_GLOBAL_DEFINED(symp)) /* keep undefined syms */
159 /* keep (C) symbols which are on the keep list */
160 if(SYMSTR(symp)[0] == '_' && in_keep_list(SYMSTR(symp) + 1))
167 * Check whether the relocation entries reference any symbols that we
168 * just zapped. I don't know whether ld can handle this case, but I
169 * haven't encountered it yet. These checks are here so that the program
170 * doesn't fail silently should such symbols be encountered.
173 for(relp = textrel; relp < textrel + ntextrel; relp++)
174 check_reloc(filename, relp);
175 for(relp = datarel; relp < datarel + ndatarel; relp++)
176 check_reloc(filename, relp);
179 * Write the .o file back out to disk. XXX - Really, we only need to
180 * write the symbol table entries back out.
182 lseek(inf, 0, SEEK_SET);
183 if((rc = write(inf, aoutdata, infstat.st_size)) < infstat.st_size) {
184 fprintf(stderr, "%s: write error: %s\n", filename,
185 rc == -1? strerror(errno) : "short write");
193 static void check_reloc(const char *filename, struct relocation_info *relp)
195 /* bail out if we zapped a symbol that is needed */
196 if(IS_SYMBOL_RELOC(relp) && symbase[relp->r_symbolnum].n_type == 0) {
198 "%s: oops, have hanging relocation for %s: bailing out!\n",
199 filename, SYMSTR(&symbase[relp->r_symbolnum]));
204 #endif /* defined(NLIST_AOUT) */