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dcfdbac7 JB |
1 | /* Unexec for HP 9000 Series 800 machines. |
2 | Bob Desinger <hpsemc!bd@hplabs.hp.com> | |
3 | ||
4 | Note that the GNU project considers support for HP operation a | |
5 | peripheral activity which should not be allowed to divert effort | |
6 | from development of the GNU system. Changes in this code will be | |
7 | installed when users send them in, but aside from that we don't | |
8 | plan to think about it, or about whether other Emacs maintenance | |
9 | might break it. | |
10 | ||
11 | ||
12 | Unexec creates a copy of the old a.out file, and replaces the old data | |
13 | area with the current data area. When the new file is executed, the | |
14 | process will see the same data structures and data values that the | |
15 | original process had when unexec was called. | |
16 | ||
17 | Unlike other versions of unexec, this one copies symbol table and | |
18 | debug information to the new a.out file. Thus, the new a.out file | |
19 | may be debugged with symbolic debuggers. | |
20 | ||
21 | If you fix any bugs in this, I'd like to incorporate your fixes. | |
22 | Send them to uunet!hpda!hpsemc!jmorris or jmorris%hpsemc@hplabs.HP.COM. | |
23 | ||
24 | CAVEATS: | |
25 | This routine saves the current value of all static and external | |
26 | variables. This means that any data structure that needs to be | |
27 | initialized must be explicitly reset. Variables will not have their | |
28 | expected default values. | |
29 | ||
30 | Unfortunately, the HP-UX signal handler has internal initialization | |
31 | flags which are not explicitly reset. Thus, for signals to work in | |
32 | conjunction with this routine, the following code must executed when | |
33 | the new process starts up. | |
34 | ||
35 | void _sigreturn(); | |
36 | ... | |
37 | sigsetreturn(_sigreturn); | |
38 | */ | |
39 | \f | |
40 | #include <stdio.h> | |
41 | #include <fcntl.h> | |
42 | #include <errno.h> | |
43 | ||
44 | #include <a.out.h> | |
45 | ||
46 | #define NBPG 2048 | |
47 | #define roundup(x,n) ( ( (x)+(n-1) ) & ~(n-1) ) /* n is power of 2 */ | |
48 | #define min(x,y) ( ((x)<(y))?(x):(y) ) | |
49 | ||
50 | ||
51 | /* Create a new a.out file, same as old but with current data space */ | |
52 | ||
53 | unexec(new_name, old_name, new_end_of_text, dummy1, dummy2) | |
54 | char new_name[]; /* name of the new a.out file to be created */ | |
55 | char old_name[]; /* name of the old a.out file */ | |
56 | char *new_end_of_text; /* ptr to new edata/etext; NOT USED YET */ | |
57 | int dummy1, dummy2; /* not used by emacs */ | |
58 | { | |
59 | int old, new; | |
60 | int old_size, new_size; | |
61 | struct header hdr; | |
62 | struct som_exec_auxhdr auxhdr; | |
d427b66a | 63 | long i; |
dcfdbac7 JB |
64 | |
65 | /* For the greatest flexibility, should create a temporary file in | |
66 | the same directory as the new file. When everything is complete, | |
67 | rename the temp file to the new name. | |
68 | This way, a program could update its own a.out file even while | |
69 | it is still executing. If problems occur, everything is still | |
70 | intact. NOT implemented. */ | |
71 | ||
72 | /* Open the input and output a.out files */ | |
73 | old = open(old_name, O_RDONLY); | |
74 | if (old < 0) | |
75 | { perror(old_name); exit(1); } | |
76 | new = open(new_name, O_CREAT|O_RDWR|O_TRUNC, 0777); | |
77 | if (new < 0) | |
78 | { perror(new_name); exit(1); } | |
79 | ||
80 | /* Read the old headers */ | |
81 | read_header(old, &hdr, &auxhdr); | |
82 | ||
83 | /* Decide how large the new and old data areas are */ | |
84 | old_size = auxhdr.exec_dsize; | |
d427b66a JB |
85 | /* I suspect these two statements are separate |
86 | to avoid a compiler bug in hpux version 8. */ | |
87 | i = sbrk (0); | |
88 | new_size = i - auxhdr.exec_dmem; | |
dcfdbac7 JB |
89 | |
90 | /* Copy the old file to the new, up to the data space */ | |
91 | lseek(old, 0, 0); | |
92 | copy_file(old, new, auxhdr.exec_dfile); | |
93 | ||
94 | /* Skip the old data segment and write a new one */ | |
95 | lseek(old, old_size, 1); | |
96 | save_data_space(new, &hdr, &auxhdr, new_size); | |
97 | ||
98 | /* Copy the rest of the file */ | |
99 | copy_rest(old, new); | |
100 | ||
101 | /* Update file pointers since we probably changed size of data area */ | |
102 | update_file_ptrs(new, &hdr, &auxhdr, auxhdr.exec_dfile, new_size-old_size); | |
103 | ||
104 | /* Save the modified header */ | |
105 | write_header(new, &hdr, &auxhdr); | |
106 | ||
107 | /* Close the binary file */ | |
108 | close(old); | |
109 | close(new); | |
f3bca33c | 110 | return 0; |
dcfdbac7 JB |
111 | } |
112 | ||
113 | /* Save current data space in the file, update header. */ | |
114 | ||
115 | save_data_space(file, hdr, auxhdr, size) | |
116 | int file; | |
117 | struct header *hdr; | |
118 | struct som_exec_auxhdr *auxhdr; | |
119 | int size; | |
120 | { | |
121 | /* Write the entire data space out to the file */ | |
122 | if (write(file, auxhdr->exec_dmem, size) != size) | |
123 | { perror("Can't save new data space"); exit(1); } | |
124 | ||
125 | /* Update the header to reflect the new data size */ | |
126 | auxhdr->exec_dsize = size; | |
127 | auxhdr->exec_bsize = 0; | |
128 | } | |
129 | ||
130 | /* Update the values of file pointers when something is inserted. */ | |
131 | ||
132 | update_file_ptrs(file, hdr, auxhdr, location, offset) | |
133 | int file; | |
134 | struct header *hdr; | |
135 | struct som_exec_auxhdr *auxhdr; | |
136 | unsigned int location; | |
137 | int offset; | |
138 | { | |
139 | struct subspace_dictionary_record subspace; | |
140 | int i; | |
141 | ||
142 | /* Increase the overall size of the module */ | |
143 | hdr->som_length += offset; | |
144 | ||
145 | /* Update the various file pointers in the header */ | |
146 | #define update(ptr) if (ptr > location) ptr = ptr + offset | |
147 | update(hdr->aux_header_location); | |
148 | update(hdr->space_strings_location); | |
149 | update(hdr->init_array_location); | |
150 | update(hdr->compiler_location); | |
151 | update(hdr->symbol_location); | |
152 | update(hdr->fixup_request_location); | |
153 | update(hdr->symbol_strings_location); | |
154 | update(hdr->unloadable_sp_location); | |
155 | update(auxhdr->exec_tfile); | |
156 | update(auxhdr->exec_dfile); | |
157 | ||
158 | /* Do for each subspace dictionary entry */ | |
159 | lseek(file, hdr->subspace_location, 0); | |
160 | for (i = 0; i < hdr->subspace_total; i++) | |
161 | { | |
162 | if (read(file, &subspace, sizeof(subspace)) != sizeof(subspace)) | |
163 | { perror("Can't read subspace record"); exit(1); } | |
164 | ||
165 | /* If subspace has a file location, update it */ | |
166 | if (subspace.initialization_length > 0 | |
167 | && subspace.file_loc_init_value > location) | |
168 | { | |
169 | subspace.file_loc_init_value += offset; | |
170 | lseek(file, -sizeof(subspace), 1); | |
171 | if (write(file, &subspace, sizeof(subspace)) != sizeof(subspace)) | |
172 | { perror("Can't update subspace record"); exit(1); } | |
173 | } | |
174 | } | |
175 | ||
176 | /* Do for each initialization pointer record */ | |
177 | /* (I don't think it applies to executable files, only relocatables) */ | |
178 | #undef update | |
179 | } | |
180 | ||
181 | /* Read in the header records from an a.out file. */ | |
182 | ||
183 | read_header(file, hdr, auxhdr) | |
184 | int file; | |
185 | struct header *hdr; | |
186 | struct som_exec_auxhdr *auxhdr; | |
187 | { | |
188 | ||
189 | /* Read the header in */ | |
190 | lseek(file, 0, 0); | |
191 | if (read(file, hdr, sizeof(*hdr)) != sizeof(*hdr)) | |
192 | { perror("Couldn't read header from a.out file"); exit(1); } | |
193 | ||
194 | if (hdr->a_magic != EXEC_MAGIC && hdr->a_magic != SHARE_MAGIC | |
195 | && hdr->a_magic != DEMAND_MAGIC) | |
196 | { | |
197 | fprintf(stderr, "a.out file doesn't have legal magic number\n"); | |
198 | exit(1); | |
199 | } | |
200 | ||
201 | lseek(file, hdr->aux_header_location, 0); | |
202 | if (read(file, auxhdr, sizeof(*auxhdr)) != sizeof(*auxhdr)) | |
203 | { | |
204 | perror("Couldn't read auxiliary header from a.out file"); | |
205 | exit(1); | |
206 | } | |
207 | } | |
208 | ||
209 | /* Write out the header records into an a.out file. */ | |
210 | ||
211 | write_header(file, hdr, auxhdr) | |
212 | int file; | |
213 | struct header *hdr; | |
214 | struct som_exec_auxhdr *auxhdr; | |
215 | { | |
216 | /* Update the checksum */ | |
217 | hdr->checksum = calculate_checksum(hdr); | |
218 | ||
219 | /* Write the header back into the a.out file */ | |
220 | lseek(file, 0, 0); | |
221 | if (write(file, hdr, sizeof(*hdr)) != sizeof(*hdr)) | |
222 | { perror("Couldn't write header to a.out file"); exit(1); } | |
223 | lseek(file, hdr->aux_header_location, 0); | |
224 | if (write(file, auxhdr, sizeof(*auxhdr)) != sizeof(*auxhdr)) | |
225 | { perror("Couldn't write auxiliary header to a.out file"); exit(1); } | |
226 | } | |
227 | ||
228 | /* Calculate the checksum of a SOM header record. */ | |
229 | ||
230 | calculate_checksum(hdr) | |
231 | struct header *hdr; | |
232 | { | |
233 | int checksum, i, *ptr; | |
234 | ||
235 | checksum = 0; ptr = (int *) hdr; | |
236 | ||
237 | for (i=0; i<sizeof(*hdr)/sizeof(int)-1; i++) | |
238 | checksum ^= ptr[i]; | |
239 | ||
240 | return(checksum); | |
241 | } | |
242 | ||
243 | /* Copy size bytes from the old file to the new one. */ | |
244 | ||
245 | copy_file(old, new, size) | |
246 | int new, old; | |
247 | int size; | |
248 | { | |
249 | int len; | |
250 | int buffer[8196]; /* word aligned will be faster */ | |
251 | ||
252 | for (; size > 0; size -= len) | |
253 | { | |
254 | len = min(size, sizeof(buffer)); | |
255 | if (read(old, buffer, len) != len) | |
256 | { perror("Read failure on a.out file"); exit(1); } | |
257 | if (write(new, buffer, len) != len) | |
258 | { perror("Write failure in a.out file"); exit(1); } | |
259 | } | |
260 | } | |
261 | ||
262 | /* Copy the rest of the file, up to EOF. */ | |
263 | ||
264 | copy_rest(old, new) | |
265 | int new, old; | |
266 | { | |
267 | int buffer[4096]; | |
268 | int len; | |
269 | ||
270 | /* Copy bytes until end of file or error */ | |
271 | while ( (len = read(old, buffer, sizeof(buffer))) > 0) | |
272 | if (write(new, buffer, len) != len) break; | |
273 | ||
274 | if (len != 0) | |
275 | { perror("Unable to copy the rest of the file"); exit(1); } | |
276 | } | |
277 | ||
278 | #ifdef DEBUG | |
279 | display_header(hdr, auxhdr) | |
280 | struct header *hdr; | |
281 | struct som_exec_auxhdr *auxhdr; | |
282 | { | |
283 | /* Display the header information (debug) */ | |
284 | printf("\n\nFILE HEADER\n"); | |
285 | printf("magic number %d \n", hdr->a_magic); | |
286 | printf("text loc %.8x size %d \n", auxhdr->exec_tmem, auxhdr->exec_tsize); | |
287 | printf("data loc %.8x size %d \n", auxhdr->exec_dmem, auxhdr->exec_dsize); | |
288 | printf("entry %x \n", auxhdr->exec_entry); | |
289 | printf("Bss segment size %u\n", auxhdr->exec_bsize); | |
290 | printf("\n"); | |
291 | printf("data file loc %d size %d\n", | |
292 | auxhdr->exec_dfile, auxhdr->exec_dsize); | |
293 | printf("som_length %d\n", hdr->som_length); | |
294 | printf("unloadable sploc %d size %d\n", | |
295 | hdr->unloadable_sp_location, hdr->unloadable_sp_size); | |
296 | } | |
297 | #endif /* DEBUG */ |