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d427b66a JB |
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 | ||
20c92ac7 | 9 | Copyright (C) 1988, 1994 Free Software Foundation, Inc. |
d427b66a JB |
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 | |
20c92ac7 | 15 | the Free Software Foundation; either version 2, or (at your option) |
d427b66a JB |
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 | ||
18160b98 | 43 | #include <config.h> |
d427b66a JB |
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; | |
20c92ac7 | 69 | extern char *strerror (); |
d427b66a JB |
70 | #define EEOF -1 |
71 | ||
72 | #ifndef L_SET | |
73 | #define L_SET 0 | |
74 | #endif | |
75 | \f | |
76 | /* Should check the magic number of the old executable; | |
77 | not yet written. */ | |
78 | check_exec (x) | |
79 | struct xexec *x; | |
80 | { | |
81 | } | |
82 | ||
83 | ||
84 | unexec (new_name, a_name, data_start, bss_start, entry_address) | |
85 | char *new_name, *a_name; | |
86 | unsigned data_start, bss_start, entry_address; | |
87 | { | |
88 | char *sbrk (), *datalim = sbrk (0), *data_org; | |
89 | long segpos, textseen, textpos, textlen, datapos, datadiff, datalen; | |
90 | ||
91 | struct xexec u_xexec, /* a.out header */ | |
92 | *u_xexecp = &u_xexec; | |
93 | struct xext u_xext, /* extended header */ | |
94 | *u_xextp = &u_xext; | |
95 | struct xseg u_xseg, /* segment table entry */ | |
96 | *u_xsegp = &u_xseg; | |
97 | int i, nsegs, isdata = 0, infd, outfd; | |
98 | ||
99 | infd = open (a_name, O_RDONLY, 0); | |
100 | if (infd < 0) fatal_unexec ("opening %s", a_name); | |
101 | ||
102 | outfd = creat (new_name, 0666); | |
103 | if (outfd < 0) fatal_unexec ("creating %s", new_name); | |
104 | ||
105 | READ (infd, u_xexecp, sizeof (struct xexec), | |
106 | "error reading %s", a_name); | |
107 | check_exec (u_xexecp); | |
108 | READ (infd, u_xextp, sizeof (struct xext), | |
109 | "error reading %s", a_name); | |
110 | segpos = u_xextp->xe_segpos; | |
111 | nsegs = u_xextp->xe_segsize / sizeof (struct xseg); | |
112 | SEEK (infd, segpos, "seek error on %s", a_name); | |
113 | for (i = 0; i < nsegs; i ++) | |
114 | { | |
115 | READ (infd, u_xsegp, sizeof (struct xseg), | |
116 | "error reading %s", a_name); | |
117 | switch (u_xsegp->xs_type) | |
118 | { | |
119 | case XS_TTEXT: | |
120 | { | |
121 | if (i == 0) | |
122 | { | |
123 | textpos = u_xsegp->xs_filpos; | |
124 | textlen = u_xsegp->xs_psize; | |
125 | break; | |
126 | } | |
127 | fatal_unexec ("invalid text segment in %s", a_name); | |
128 | } | |
129 | case XS_TDATA: | |
130 | { | |
131 | if (i == 1) | |
132 | { | |
133 | datapos = u_xsegp->xs_filpos; | |
134 | datalen = datalim - (data_org = (char *)(u_xsegp->xs_rbase)); | |
135 | datadiff = datalen - u_xsegp->xs_psize; | |
136 | break; | |
137 | } | |
138 | fatal_unexec ("invalid data segment in %s", a_name); | |
139 | } | |
140 | default: | |
141 | { | |
142 | if (i > 1) break; | |
143 | fatal_unexec ("invalid segment record in %s", a_name); | |
144 | } | |
145 | } | |
146 | } | |
147 | u_xexecp->x_data = datalen; | |
148 | u_xexecp->x_bss = 0; | |
149 | WRITE (outfd, u_xexecp, sizeof (struct xexec), | |
150 | "error writing %s", new_name); | |
151 | WRITE (outfd, u_xextp, sizeof (struct xext), | |
152 | "error writing %s", new_name); | |
153 | SEEK (infd, segpos, "seek error on %s", a_name); | |
154 | SEEK (outfd, segpos, "seek error on %s", new_name); | |
155 | ||
156 | /* Copy the text segment record verbatim. */ | |
157 | ||
158 | copyrec (infd, outfd, sizeof (struct xseg), a_name, new_name); | |
159 | ||
160 | /* Read, modify, write the data segment record. */ | |
161 | ||
162 | READ (infd, u_xsegp, sizeof (struct xseg), | |
163 | "error reading %s", a_name); | |
164 | u_xsegp->xs_psize = u_xsegp->xs_vsize = datalen; | |
165 | u_xsegp->xs_attr &= (~XS_AITER & ~XS_ABSS); | |
166 | WRITE (outfd, u_xsegp, sizeof (struct xseg), | |
167 | "error writing %s", new_name); | |
168 | ||
169 | /* Now copy any additional segment records, adjusting their | |
170 | file position field */ | |
171 | ||
172 | for (i = 2; i < nsegs; i++) | |
173 | { | |
174 | READ (infd, u_xsegp, sizeof (struct xseg), | |
175 | "error reading %s", a_name); | |
176 | u_xsegp->xs_filpos += datadiff; | |
177 | WRITE (outfd, u_xsegp, sizeof (struct xseg), | |
178 | "error writing %s", new_name); | |
179 | } | |
180 | ||
181 | SEEK (infd, textpos, "seek error on %s", a_name); | |
182 | SEEK (outfd, textpos, "seek error on %s", new_name); | |
183 | copyrec (infd, outfd, textlen, a_name, new_name); | |
184 | ||
185 | SEEK (outfd, datapos, "seek error on %s", new_name); | |
186 | WRITE (outfd, data_org, datalen, | |
187 | "write error on %s", new_name); | |
188 | ||
189 | for (i = 2, segpos += (2 * sizeof (struct xseg)); | |
190 | i < nsegs; | |
191 | i++, segpos += sizeof (struct xseg)) | |
192 | { | |
193 | SEEK (infd, segpos, "seek error on %s", a_name); | |
194 | READ (infd, u_xsegp, sizeof (struct xseg), | |
195 | "read error on %s", a_name); | |
196 | SEEK (infd, u_xsegp->xs_filpos, "seek error on %s", a_name); | |
197 | /* We should be at eof in the output file here, but we must seek | |
198 | because the xs_filpos and xs_psize fields in symbol table | |
199 | segments are inconsistent. */ | |
200 | SEEK (outfd, u_xsegp->xs_filpos + datadiff, "seek error on %s", new_name); | |
201 | copyrec (infd, outfd, u_xsegp->xs_psize, a_name, new_name); | |
202 | } | |
203 | close (infd); | |
204 | close (outfd); | |
205 | mark_x (new_name); | |
206 | return 0; | |
207 | } | |
208 | ||
209 | copyrec (infd, outfd, len, in_name, out_name) | |
210 | int infd, outfd, len; | |
211 | char *in_name, *out_name; | |
212 | { | |
213 | char buf[BUFSIZ]; | |
214 | int chunk; | |
215 | ||
216 | while (len) | |
217 | { | |
218 | chunk = BUFSIZ; | |
219 | if (chunk > len) | |
220 | chunk = len; | |
221 | READ (infd, buf, chunk, "error reading %s", in_name); | |
222 | WRITE (outfd, buf, chunk, "error writing %s", out_name); | |
223 | len -= chunk; | |
224 | } | |
225 | } | |
226 | ||
227 | /* | |
228 | * mark_x | |
229 | * | |
eb8c3be9 | 230 | * After successfully building the new a.out, mark it executable |
d427b66a JB |
231 | */ |
232 | static | |
233 | mark_x (name) | |
234 | char *name; | |
235 | { | |
236 | struct stat sbuf; | |
237 | int um = umask (777); | |
238 | umask (um); | |
239 | if (stat (name, &sbuf) < 0) | |
240 | fatal_unexec ("getting protection on %s", name); | |
241 | sbuf.st_mode |= 0111 & ~um; | |
242 | if (chmod (name, sbuf.st_mode) < 0) | |
243 | fatal_unexec ("setting protection on %s", name); | |
244 | } | |
245 | ||
246 | static void | |
247 | fatal_unexec (s, va_alist) | |
248 | va_dcl | |
249 | { | |
250 | va_list ap; | |
251 | if (errno == EEOF) | |
252 | fputs ("unexec: unexpected end of file, ", stderr); | |
d427b66a | 253 | else |
20c92ac7 | 254 | fprintf (stderr, "unexec: %s, ", strerror (errno)); |
d427b66a JB |
255 | va_start (ap); |
256 | _doprnt (s, ap, stderr); | |
257 | fputs (".\n", stderr); | |
258 | exit (1); | |
259 | } |