/* Unexec for Xenix. Copyright (C) 1988, 1994 Free Software Foundation, Inc. This file is part of XEmacs. XEmacs is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. XEmacs is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with XEmacs; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* Synched up with: FSF 19.31. */ /* On 80386 Xenix, segmentation screws prevent us from modifying the text segment at all. We basically just plug a new value for "data segment size" into the countless headers and copy the other records straight through. The data segment is ORG'ed at the xs_rbase value of the data segment's xseg record (always @ 0x1880000, thanks to the "sophisticated memory management hardware" of the chip) and extends to sbrk(0), exactly. This code is afraid to malloc (should it be?), and alloca has to be the wimpy, malloc-based version; consequently, data is usually copied in smallish chunks. gb@entity.com */ #include #include #include #include #include #include #include #include static void fatal_unexec (); #define READ(_fd, _buffer, _size, _error_message, _error_arg) \ errno = EEOF; \ if (read(_fd, _buffer, _size) != _size) \ fatal_unexec(_error_message, _error_arg); #define WRITE(_fd, _buffer, _size, _error_message, _error_arg) \ if (write(_fd, _buffer, _size) != _size) \ fatal_unexec(_error_message, _error_arg); #define SEEK(_fd, _position, _error_message, _error_arg) \ errno = EEOF; \ if (lseek(_fd, _position, L_SET) != _position) \ fatal_unexec(_error_message, _error_arg); extern int errno; extern char *strerror (); #define EEOF -1 #ifndef L_SET #define L_SET 0 #endif /* Should check the magic number of the old executable; not yet written. */ check_exec (x) struct xexec *x; { } unexec (new_name, a_name, data_start, bss_start, entry_address) char *new_name, *a_name; unsigned data_start, bss_start, entry_address; { char *sbrk (), *datalim = sbrk (0), *data_org; long segpos, textseen, textpos, textlen, datapos, datadiff, datalen; struct xexec u_xexec, /* a.out header */ *u_xexecp = &u_xexec; struct xext u_xext, /* extended header */ *u_xextp = &u_xext; struct xseg u_xseg, /* segment table entry */ *u_xsegp = &u_xseg; int i, nsegs, isdata = 0, infd, outfd; infd = open (a_name, O_RDONLY, 0); if (infd < 0) fatal_unexec ("opening %s", a_name); outfd = creat (new_name, 0666); if (outfd < 0) fatal_unexec ("creating %s", new_name); READ (infd, u_xexecp, sizeof (struct xexec), "error reading %s", a_name); check_exec (u_xexecp); READ (infd, u_xextp, sizeof (struct xext), "error reading %s", a_name); segpos = u_xextp->xe_segpos; nsegs = u_xextp->xe_segsize / sizeof (struct xseg); SEEK (infd, segpos, "seek error on %s", a_name); for (i = 0; i < nsegs; i ++) { READ (infd, u_xsegp, sizeof (struct xseg), "error reading %s", a_name); switch (u_xsegp->xs_type) { case XS_TTEXT: { if (i == 0) { textpos = u_xsegp->xs_filpos; textlen = u_xsegp->xs_psize; break; } fatal_unexec ("invalid text segment in %s", a_name); } case XS_TDATA: { if (i == 1) { datapos = u_xsegp->xs_filpos; datalen = datalim - (data_org = (char *)(u_xsegp->xs_rbase)); datadiff = datalen - u_xsegp->xs_psize; break; } fatal_unexec ("invalid data segment in %s", a_name); } default: { if (i > 1) break; fatal_unexec ("invalid segment record in %s", a_name); } } } u_xexecp->x_data = datalen; u_xexecp->x_bss = 0; WRITE (outfd, u_xexecp, sizeof (struct xexec), "error writing %s", new_name); WRITE (outfd, u_xextp, sizeof (struct xext), "error writing %s", new_name); SEEK (infd, segpos, "seek error on %s", a_name); SEEK (outfd, segpos, "seek error on %s", new_name); /* Copy the text segment record verbatim. */ copyrec (infd, outfd, sizeof (struct xseg), a_name, new_name); /* Read, modify, write the data segment record. */ READ (infd, u_xsegp, sizeof (struct xseg), "error reading %s", a_name); u_xsegp->xs_psize = u_xsegp->xs_vsize = datalen; u_xsegp->xs_attr &= (~XS_AITER & ~XS_ABSS); WRITE (outfd, u_xsegp, sizeof (struct xseg), "error writing %s", new_name); /* Now copy any additional segment records, adjusting their file position field */ for (i = 2; i < nsegs; i++) { READ (infd, u_xsegp, sizeof (struct xseg), "error reading %s", a_name); u_xsegp->xs_filpos += datadiff; WRITE (outfd, u_xsegp, sizeof (struct xseg), "error writing %s", new_name); } SEEK (infd, textpos, "seek error on %s", a_name); SEEK (outfd, textpos, "seek error on %s", new_name); copyrec (infd, outfd, textlen, a_name, new_name); SEEK (outfd, datapos, "seek error on %s", new_name); WRITE (outfd, data_org, datalen, "write error on %s", new_name); for (i = 2, segpos += (2 * sizeof (struct xseg)); i < nsegs; i++, segpos += sizeof (struct xseg)) { SEEK (infd, segpos, "seek error on %s", a_name); READ (infd, u_xsegp, sizeof (struct xseg), "read error on %s", a_name); SEEK (infd, u_xsegp->xs_filpos, "seek error on %s", a_name); /* We should be at eof in the output file here, but we must seek because the xs_filpos and xs_psize fields in symbol table segments are inconsistent. */ SEEK (outfd, u_xsegp->xs_filpos + datadiff, "seek error on %s", new_name); copyrec (infd, outfd, u_xsegp->xs_psize, a_name, new_name); } close (infd); close (outfd); mark_x (new_name); return 0; } copyrec (infd, outfd, len, in_name, out_name) int infd, outfd, len; char *in_name, *out_name; { char buf[BUFSIZ]; int chunk; while (len) { chunk = BUFSIZ; if (chunk > len) chunk = len; READ (infd, buf, chunk, "error reading %s", in_name); WRITE (outfd, buf, chunk, "error writing %s", out_name); len -= chunk; } } /* * mark_x * * After successfully building the new a.out, mark it executable */ static mark_x (name) char *name; { struct stat sbuf; int um = umask (777); umask (um); if (stat (name, &sbuf) < 0) fatal_unexec ("getting protection on %s", name); sbuf.st_mode |= 0111 & ~um; if (chmod (name, sbuf.st_mode) < 0) fatal_unexec ("setting protection on %s", name); } static void fatal_unexec (s, va_alist) va_dcl { va_list ap; if (errno == EEOF) fputs ("unexec: unexpected end of file, ", stderr); else fprintf (stderr, "unexec: %s, ", strerror (errno)); va_start (ap); _doprnt (s, ap, stderr); fputs (".\n", stderr); exit (1); }