| 1 | /* Unexec for Xenix. |
| 2 | Note that the GNU project considers support for Xenix operation |
| 3 | a peripheral activity which should not be allowed to divert effort |
| 4 | from development of the GNU system. Changes in this code will be |
| 5 | installed when Xenix users send them in, but aside from that |
| 6 | we don't plan to think about it, or about whether other Emacs |
| 7 | maintenance might break it. |
| 8 | |
| 9 | Copyright (C) 1988 Free Software Foundation, Inc. |
| 10 | |
| 11 | This file is part of GNU Emacs. |
| 12 | |
| 13 | GNU Emacs is free software; you can redistribute it and/or modify |
| 14 | it under the terms of the GNU General Public License as published by |
| 15 | the Free Software Foundation; either version 1, or (at your option) |
| 16 | any later version. |
| 17 | |
| 18 | GNU Emacs is distributed in the hope that it will be useful, |
| 19 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 20 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 21 | GNU General Public License for more details. |
| 22 | |
| 23 | You should have received a copy of the GNU General Public License |
| 24 | along with GNU Emacs; see the file COPYING. If not, write to |
| 25 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ |
| 26 | |
| 27 | \f |
| 28 | |
| 29 | /* |
| 30 | On 80386 Xenix, segmentation screws prevent us from modifying the text |
| 31 | segment at all. We basically just plug a new value for "data segment |
| 32 | size" into the countless headers and copy the other records straight |
| 33 | through. The data segment is ORG'ed at the xs_rbase value of the data |
| 34 | segment's xseg record (always @ 0x1880000, thanks to the "sophisticated |
| 35 | memory management hardware" of the chip) and extends to sbrk(0), exactly. |
| 36 | This code is afraid to malloc (should it be?), and alloca has to be the |
| 37 | wimpy, malloc-based version; consequently, data is usually copied in |
| 38 | smallish chunks. |
| 39 | |
| 40 | gb@entity.com |
| 41 | */ |
| 42 | |
| 43 | #include "config.h" |
| 44 | #include <sys/types.h> |
| 45 | #include <fcntl.h> |
| 46 | #include <sys/file.h> |
| 47 | #include <sys/stat.h> |
| 48 | #include <stdio.h> |
| 49 | #include <varargs.h> |
| 50 | #include <a.out.h> |
| 51 | |
| 52 | static void fatal_unexec (); |
| 53 | |
| 54 | #define READ(_fd, _buffer, _size, _error_message, _error_arg) \ |
| 55 | errno = EEOF; \ |
| 56 | if (read(_fd, _buffer, _size) != _size) \ |
| 57 | fatal_unexec(_error_message, _error_arg); |
| 58 | |
| 59 | #define WRITE(_fd, _buffer, _size, _error_message, _error_arg) \ |
| 60 | if (write(_fd, _buffer, _size) != _size) \ |
| 61 | fatal_unexec(_error_message, _error_arg); |
| 62 | |
| 63 | #define SEEK(_fd, _position, _error_message, _error_arg) \ |
| 64 | errno = EEOF; \ |
| 65 | if (lseek(_fd, _position, L_SET) != _position) \ |
| 66 | fatal_unexec(_error_message, _error_arg); |
| 67 | |
| 68 | extern int errno; |
| 69 | extern int sys_nerr; |
| 70 | extern char *sys_errlist[]; |
| 71 | #define EEOF -1 |
| 72 | |
| 73 | #ifndef L_SET |
| 74 | #define L_SET 0 |
| 75 | #endif |
| 76 | \f |
| 77 | /* Should check the magic number of the old executable; |
| 78 | not yet written. */ |
| 79 | check_exec (x) |
| 80 | struct xexec *x; |
| 81 | { |
| 82 | } |
| 83 | |
| 84 | |
| 85 | unexec (new_name, a_name, data_start, bss_start, entry_address) |
| 86 | char *new_name, *a_name; |
| 87 | unsigned data_start, bss_start, entry_address; |
| 88 | { |
| 89 | char *sbrk (), *datalim = sbrk (0), *data_org; |
| 90 | long segpos, textseen, textpos, textlen, datapos, datadiff, datalen; |
| 91 | |
| 92 | struct xexec u_xexec, /* a.out header */ |
| 93 | *u_xexecp = &u_xexec; |
| 94 | struct xext u_xext, /* extended header */ |
| 95 | *u_xextp = &u_xext; |
| 96 | struct xseg u_xseg, /* segment table entry */ |
| 97 | *u_xsegp = &u_xseg; |
| 98 | int i, nsegs, isdata = 0, infd, outfd; |
| 99 | |
| 100 | infd = open (a_name, O_RDONLY, 0); |
| 101 | if (infd < 0) fatal_unexec ("opening %s", a_name); |
| 102 | |
| 103 | outfd = creat (new_name, 0666); |
| 104 | if (outfd < 0) fatal_unexec ("creating %s", new_name); |
| 105 | |
| 106 | READ (infd, u_xexecp, sizeof (struct xexec), |
| 107 | "error reading %s", a_name); |
| 108 | check_exec (u_xexecp); |
| 109 | READ (infd, u_xextp, sizeof (struct xext), |
| 110 | "error reading %s", a_name); |
| 111 | segpos = u_xextp->xe_segpos; |
| 112 | nsegs = u_xextp->xe_segsize / sizeof (struct xseg); |
| 113 | SEEK (infd, segpos, "seek error on %s", a_name); |
| 114 | for (i = 0; i < nsegs; i ++) |
| 115 | { |
| 116 | READ (infd, u_xsegp, sizeof (struct xseg), |
| 117 | "error reading %s", a_name); |
| 118 | switch (u_xsegp->xs_type) |
| 119 | { |
| 120 | case XS_TTEXT: |
| 121 | { |
| 122 | if (i == 0) |
| 123 | { |
| 124 | textpos = u_xsegp->xs_filpos; |
| 125 | textlen = u_xsegp->xs_psize; |
| 126 | break; |
| 127 | } |
| 128 | fatal_unexec ("invalid text segment in %s", a_name); |
| 129 | } |
| 130 | case XS_TDATA: |
| 131 | { |
| 132 | if (i == 1) |
| 133 | { |
| 134 | datapos = u_xsegp->xs_filpos; |
| 135 | datalen = datalim - (data_org = (char *)(u_xsegp->xs_rbase)); |
| 136 | datadiff = datalen - u_xsegp->xs_psize; |
| 137 | break; |
| 138 | } |
| 139 | fatal_unexec ("invalid data segment in %s", a_name); |
| 140 | } |
| 141 | default: |
| 142 | { |
| 143 | if (i > 1) break; |
| 144 | fatal_unexec ("invalid segment record in %s", a_name); |
| 145 | } |
| 146 | } |
| 147 | } |
| 148 | u_xexecp->x_data = datalen; |
| 149 | u_xexecp->x_bss = 0; |
| 150 | WRITE (outfd, u_xexecp, sizeof (struct xexec), |
| 151 | "error writing %s", new_name); |
| 152 | WRITE (outfd, u_xextp, sizeof (struct xext), |
| 153 | "error writing %s", new_name); |
| 154 | SEEK (infd, segpos, "seek error on %s", a_name); |
| 155 | SEEK (outfd, segpos, "seek error on %s", new_name); |
| 156 | |
| 157 | /* Copy the text segment record verbatim. */ |
| 158 | |
| 159 | copyrec (infd, outfd, sizeof (struct xseg), a_name, new_name); |
| 160 | |
| 161 | /* Read, modify, write the data segment record. */ |
| 162 | |
| 163 | READ (infd, u_xsegp, sizeof (struct xseg), |
| 164 | "error reading %s", a_name); |
| 165 | u_xsegp->xs_psize = u_xsegp->xs_vsize = datalen; |
| 166 | u_xsegp->xs_attr &= (~XS_AITER & ~XS_ABSS); |
| 167 | WRITE (outfd, u_xsegp, sizeof (struct xseg), |
| 168 | "error writing %s", new_name); |
| 169 | |
| 170 | /* Now copy any additional segment records, adjusting their |
| 171 | file position field */ |
| 172 | |
| 173 | for (i = 2; i < nsegs; i++) |
| 174 | { |
| 175 | READ (infd, u_xsegp, sizeof (struct xseg), |
| 176 | "error reading %s", a_name); |
| 177 | u_xsegp->xs_filpos += datadiff; |
| 178 | WRITE (outfd, u_xsegp, sizeof (struct xseg), |
| 179 | "error writing %s", new_name); |
| 180 | } |
| 181 | |
| 182 | SEEK (infd, textpos, "seek error on %s", a_name); |
| 183 | SEEK (outfd, textpos, "seek error on %s", new_name); |
| 184 | copyrec (infd, outfd, textlen, a_name, new_name); |
| 185 | |
| 186 | SEEK (outfd, datapos, "seek error on %s", new_name); |
| 187 | WRITE (outfd, data_org, datalen, |
| 188 | "write error on %s", new_name); |
| 189 | |
| 190 | for (i = 2, segpos += (2 * sizeof (struct xseg)); |
| 191 | i < nsegs; |
| 192 | i++, segpos += sizeof (struct xseg)) |
| 193 | { |
| 194 | SEEK (infd, segpos, "seek error on %s", a_name); |
| 195 | READ (infd, u_xsegp, sizeof (struct xseg), |
| 196 | "read error on %s", a_name); |
| 197 | SEEK (infd, u_xsegp->xs_filpos, "seek error on %s", a_name); |
| 198 | /* We should be at eof in the output file here, but we must seek |
| 199 | because the xs_filpos and xs_psize fields in symbol table |
| 200 | segments are inconsistent. */ |
| 201 | SEEK (outfd, u_xsegp->xs_filpos + datadiff, "seek error on %s", new_name); |
| 202 | copyrec (infd, outfd, u_xsegp->xs_psize, a_name, new_name); |
| 203 | } |
| 204 | close (infd); |
| 205 | close (outfd); |
| 206 | mark_x (new_name); |
| 207 | return 0; |
| 208 | } |
| 209 | |
| 210 | copyrec (infd, outfd, len, in_name, out_name) |
| 211 | int infd, outfd, len; |
| 212 | char *in_name, *out_name; |
| 213 | { |
| 214 | char buf[BUFSIZ]; |
| 215 | int chunk; |
| 216 | |
| 217 | while (len) |
| 218 | { |
| 219 | chunk = BUFSIZ; |
| 220 | if (chunk > len) |
| 221 | chunk = len; |
| 222 | READ (infd, buf, chunk, "error reading %s", in_name); |
| 223 | WRITE (outfd, buf, chunk, "error writing %s", out_name); |
| 224 | len -= chunk; |
| 225 | } |
| 226 | } |
| 227 | |
| 228 | /* |
| 229 | * mark_x |
| 230 | * |
| 231 | * After succesfully building the new a.out, mark it executable |
| 232 | */ |
| 233 | static |
| 234 | mark_x (name) |
| 235 | char *name; |
| 236 | { |
| 237 | struct stat sbuf; |
| 238 | int um = umask (777); |
| 239 | umask (um); |
| 240 | if (stat (name, &sbuf) < 0) |
| 241 | fatal_unexec ("getting protection on %s", name); |
| 242 | sbuf.st_mode |= 0111 & ~um; |
| 243 | if (chmod (name, sbuf.st_mode) < 0) |
| 244 | fatal_unexec ("setting protection on %s", name); |
| 245 | } |
| 246 | |
| 247 | static void |
| 248 | fatal_unexec (s, va_alist) |
| 249 | va_dcl |
| 250 | { |
| 251 | va_list ap; |
| 252 | if (errno == EEOF) |
| 253 | fputs ("unexec: unexpected end of file, ", stderr); |
| 254 | else if (errno < sys_nerr) |
| 255 | fprintf (stderr, "unexec: %s, ", sys_errlist[errno]); |
| 256 | else |
| 257 | fprintf (stderr, "unexec: error code %d, ", errno); |
| 258 | va_start (ap); |
| 259 | _doprnt (s, ap, stderr); |
| 260 | fputs (".\n", stderr); |
| 261 | exit (1); |
| 262 | } |