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d427b66a JB |
1 | /* Modified version of unexec for convex machines. |
2 | Note that the GNU project considers support for the peculiarities | |
3 | of the Convex operating system a peripheral activity which should | |
4 | not be allowed to divert effort from development of the GNU system. | |
5 | Changes in this code will be installed when Convex system | |
6 | maintainers send them in, but aside from that we don't plan to | |
7 | think about it, or about whether other Emacs maintenance might | |
8 | break it. | |
9 | ||
10 | Copyright (C) 1985, 1986, 1988 Free Software Foundation, Inc. | |
11 | ||
12 | This file is part of GNU Emacs. | |
13 | ||
14 | GNU Emacs is free software; you can redistribute it and/or modify | |
15 | it under the terms of the GNU General Public License as published by | |
7c938215 | 16 | the Free Software Foundation; either version 2, or (at your option) |
d427b66a JB |
17 | any later version. |
18 | ||
19 | GNU Emacs is distributed in the hope that it will be useful, | |
20 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
21 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
22 | GNU General Public License for more details. | |
23 | ||
24 | You should have received a copy of the GNU General Public License | |
25 | along with GNU Emacs; see the file COPYING. If not, write to | |
3b7ad313 EN |
26 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
27 | Boston, MA 02111-1307, USA. */ | |
d427b66a JB |
28 | |
29 | ||
30 | /* modified for C-1 arch by jthomp@convex 871103 */ | |
31 | /* Corrected to support convex SOFF object file formats and thread specific | |
32 | * regions. streepy@convex 890302 | |
33 | */ | |
34 | ||
35 | /* | |
36 | * unexec.c - Convert a running program into an a.out file. | |
37 | * | |
38 | * Author: Spencer W. Thomas | |
39 | * Computer Science Dept. | |
40 | * University of Utah | |
41 | * Date: Tue Mar 2 1982 | |
42 | * Modified heavily since then. | |
43 | * | |
44 | * Synopsis: | |
45 | * unexec (new_name, a_name, data_start, bss_start, entry_address) | |
46 | * char *new_name, *a_name; | |
47 | * unsigned data_start, bss_start, entry_address; | |
48 | * | |
49 | * Takes a snapshot of the program and makes an a.out format file in the | |
50 | * file named by the string argument new_name. | |
51 | * If a_name is non-NULL, the symbol table will be taken from the given file. | |
52 | * On some machines, an existing a_name file is required. | |
53 | * | |
54 | * The boundaries within the a.out file may be adjusted with the data_start | |
55 | * and bss_start arguments. Either or both may be given as 0 for defaults. | |
56 | * | |
57 | * Data_start gives the boundary between the text segment and the data | |
58 | * segment of the program. The text segment can contain shared, read-only | |
59 | * program code and literal data, while the data segment is always unshared | |
60 | * and unprotected. Data_start gives the lowest unprotected address. | |
61 | * The value you specify may be rounded down to a suitable boundary | |
62 | * as required by the machine you are using. | |
63 | * | |
64 | * Specifying zero for data_start means the boundary between text and data | |
65 | * should not be the same as when the program was loaded. | |
66 | * If NO_REMAP is defined, the argument data_start is ignored and the | |
67 | * segment boundaries are never changed. | |
68 | * | |
69 | * Bss_start indicates how much of the data segment is to be saved in the | |
70 | * a.out file and restored when the program is executed. It gives the lowest | |
71 | * unsaved address, and is rounded up to a page boundary. The default when 0 | |
72 | * is given assumes that the entire data segment is to be stored, including | |
73 | * the previous data and bss as well as any additional storage allocated with | |
74 | * break (2). | |
75 | * | |
76 | * The new file is set up to start at entry_address. | |
77 | * | |
78 | * If you make improvements I'd like to get them too. | |
79 | * harpo!utah-cs!thomas, thomas@Utah-20 | |
80 | * | |
81 | */ | |
82 | ||
83 | /* There are several compilation parameters affecting unexec: | |
84 | ||
85 | * COFF | |
86 | ||
87 | Define this if your system uses COFF for executables. | |
88 | Otherwise we assume you use Berkeley format. | |
89 | ||
90 | * NO_REMAP | |
91 | ||
92 | Define this if you do not want to try to save Emacs's pure data areas | |
93 | as part of the text segment. | |
94 | ||
95 | Saving them as text is good because it allows users to share more. | |
96 | ||
97 | However, on machines that locate the text area far from the data area, | |
98 | the boundary cannot feasibly be moved. Such machines require | |
99 | NO_REMAP. | |
100 | ||
101 | Also, remapping can cause trouble with the built-in startup routine | |
102 | /lib/crt0.o, which defines `environ' as an initialized variable. | |
103 | Dumping `environ' as pure does not work! So, to use remapping, | |
104 | you must write a startup routine for your machine in Emacs's crt0.c. | |
105 | If NO_REMAP is defined, Emacs uses the system's crt0.o. | |
106 | ||
107 | * SECTION_ALIGNMENT | |
108 | ||
109 | Some machines that use COFF executables require that each section | |
110 | start on a certain boundary *in the COFF file*. Such machines should | |
111 | define SECTION_ALIGNMENT to a mask of the low-order bits that must be | |
112 | zero on such a boundary. This mask is used to control padding between | |
113 | segments in the COFF file. | |
114 | ||
115 | If SECTION_ALIGNMENT is not defined, the segments are written | |
116 | consecutively with no attempt at alignment. This is right for | |
117 | unmodified system V. | |
118 | ||
119 | * SEGMENT_MASK | |
120 | ||
121 | Some machines require that the beginnings and ends of segments | |
122 | *in core* be on certain boundaries. For most machines, a page | |
123 | boundary is sufficient. That is the default. When a larger | |
124 | boundary is needed, define SEGMENT_MASK to a mask of | |
125 | the bits that must be zero on such a boundary. | |
126 | ||
127 | * A_TEXT_OFFSET(HDR) | |
128 | ||
129 | Some machines count the a.out header as part of the size of the text | |
130 | segment (a_text); they may actually load the header into core as the | |
131 | first data in the text segment. Some have additional padding between | |
132 | the header and the real text of the program that is counted in a_text. | |
133 | ||
134 | For these machines, define A_TEXT_OFFSET(HDR) to examine the header | |
135 | structure HDR and return the number of bytes to add to `a_text' | |
136 | before writing it (above and beyond the number of bytes of actual | |
137 | program text). HDR's standard fields are already correct, except that | |
138 | this adjustment to the `a_text' field has not yet been made; | |
139 | thus, the amount of offset can depend on the data in the file. | |
177c0ea7 | 140 | |
d427b66a JB |
141 | * A_TEXT_SEEK(HDR) |
142 | ||
143 | If defined, this macro specifies the number of bytes to seek into the | |
144 | a.out file before starting to write the text segment.a | |
145 | ||
146 | * EXEC_MAGIC | |
147 | ||
148 | For machines using COFF, this macro, if defined, is a value stored | |
149 | into the magic number field of the output file. | |
150 | ||
151 | * ADJUST_EXEC_HEADER | |
152 | ||
153 | This macro can be used to generate statements to adjust or | |
154 | initialize nonstandard fields in the file header | |
155 | ||
156 | * ADDR_CORRECT(ADDR) | |
157 | ||
158 | Macro to correct an int which is the bit pattern of a pointer to a byte | |
159 | into an int which is the number of a byte. | |
160 | ||
161 | This macro has a default definition which is usually right. | |
162 | This default definition is a no-op on most machines (where a | |
163 | pointer looks like an int) but not on all machines. | |
164 | ||
165 | */ | |
166 | ||
18160b98 | 167 | #include <config.h> |
d427b66a JB |
168 | #define PERROR(file) report_error (file, new) |
169 | ||
170 | #include <a.out.h> | |
171 | /* Define getpagesize () if the system does not. | |
172 | Note that this may depend on symbols defined in a.out.h | |
173 | */ | |
174 | #include "getpagesize.h" | |
175 | ||
176 | #include <sys/types.h> | |
177 | #include <stdio.h> | |
178 | #include <sys/stat.h> | |
179 | #include <errno.h> | |
180 | ||
181 | extern char *start_of_text (); /* Start of text */ | |
182 | extern char *start_of_data (); /* Start of initialized data */ | |
183 | ||
184 | #include <machine/filehdr.h> | |
185 | #include <machine/opthdr.h> | |
186 | #include <machine/scnhdr.h> | |
187 | #include <machine/pte.h> | |
188 | ||
189 | static long block_copy_start; /* Old executable start point */ | |
190 | static struct filehdr f_hdr; /* File header */ | |
191 | static struct opthdr f_ohdr; /* Optional file header (a.out) */ | |
192 | long bias; /* Bias to add for growth */ | |
193 | #define SYMS_START block_copy_start | |
194 | ||
195 | static long text_scnptr; | |
196 | static long data_scnptr; | |
197 | ||
198 | static int pagemask; | |
199 | static int pagesz; | |
200 | ||
201 | static | |
202 | report_error (file, fd) | |
203 | char *file; | |
204 | int fd; | |
205 | { | |
206 | if (fd) | |
207 | close (fd); | |
208 | error ("Failure operating on %s", file); | |
209 | } | |
210 | ||
211 | #define ERROR0(msg) report_error_1 (new, msg, 0, 0); return -1 | |
212 | #define ERROR1(msg,x) report_error_1 (new, msg, x, 0); return -1 | |
213 | #define ERROR2(msg,x,y) report_error_1 (new, msg, x, y); return -1 | |
214 | ||
215 | static | |
216 | report_error_1 (fd, msg, a1, a2) | |
217 | int fd; | |
218 | char *msg; | |
219 | int a1, a2; | |
220 | { | |
221 | close (fd); | |
222 | error (msg, a1, a2); | |
223 | } | |
224 | \f | |
225 | /* **************************************************************** | |
226 | * unexec | |
227 | * | |
228 | * driving logic. | |
229 | */ | |
230 | unexec (new_name, a_name, data_start, bss_start, entry_address) | |
231 | char *new_name, *a_name; | |
232 | unsigned data_start, bss_start, entry_address; | |
233 | { | |
234 | int new, a_out = -1; | |
235 | ||
236 | if (a_name && (a_out = open (a_name, 0)) < 0) { | |
237 | PERROR (a_name); | |
238 | } | |
239 | if ((new = creat (new_name, 0666)) < 0) { | |
240 | PERROR (new_name); | |
241 | } | |
242 | ||
243 | if (make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name) < 0 | |
244 | || copy_text_and_data (new) < 0 | |
245 | || copy_sym (new, a_out, a_name, new_name) < 0 ) { | |
246 | close (new); | |
177c0ea7 | 247 | return -1; |
d427b66a JB |
248 | } |
249 | ||
250 | close (new); | |
251 | if (a_out >= 0) | |
252 | close (a_out); | |
253 | mark_x (new_name); | |
254 | return 0; | |
255 | } | |
256 | ||
257 | /* **************************************************************** | |
258 | * make_hdr | |
259 | * | |
260 | * Make the header in the new a.out from the header in core. | |
261 | * Modify the text and data sizes. | |
262 | */ | |
263 | ||
264 | struct scnhdr *stbl; /* Table of all scnhdr's */ | |
265 | struct scnhdr *f_thdr; /* Text section header */ | |
266 | struct scnhdr *f_dhdr; /* Data section header */ | |
267 | struct scnhdr *f_tdhdr; /* Thread Data section header */ | |
268 | struct scnhdr *f_bhdr; /* Bss section header */ | |
269 | struct scnhdr *f_tbhdr; /* Thread Bss section header */ | |
270 | ||
271 | static int | |
272 | make_hdr (new, a_out, data_start, bss_start, entry_address, a_name, new_name) | |
273 | int new, a_out; | |
274 | unsigned data_start, bss_start, entry_address; | |
275 | char *a_name; | |
276 | char *new_name; | |
277 | { | |
278 | register int scns; | |
279 | unsigned int bss_end; | |
280 | unsigned int eo_data; /* End of initialized data in new exec file */ | |
281 | int scntype; /* Section type */ | |
282 | int i; /* Var for sorting by vaddr */ | |
283 | struct scnhdr scntemp; /* For swapping entries in sort */ | |
284 | extern char *start_of_data(); | |
285 | ||
286 | pagemask = (pagesz = getpagesize()) - 1; | |
287 | ||
288 | /* Adjust text/data boundary. */ | |
289 | if (!data_start) | |
290 | data_start = (unsigned) start_of_data (); | |
291 | ||
292 | data_start = data_start & ~pagemask; /* (Down) to page boundary. */ | |
293 | ||
294 | bss_end = (sbrk(0) + pagemask) & ~pagemask; | |
295 | ||
296 | /* Adjust data/bss boundary. */ | |
297 | if (bss_start != 0) { | |
298 | bss_start = (bss_start + pagemask) & ~pagemask;/* (Up) to page bdry. */ | |
299 | if (bss_start > bss_end) { | |
300 | ERROR1 ("unexec: Specified bss_start (%x) is past end of program", | |
301 | bss_start); | |
302 | } | |
303 | } else | |
304 | bss_start = bss_end; | |
305 | ||
306 | if (data_start > bss_start) { /* Can't have negative data size. */ | |
307 | ERROR2 ("unexec: data_start (%x) can't be greater than bss_start (%x)", | |
308 | data_start, bss_start); | |
309 | } | |
310 | ||
311 | /* Salvage as much info from the existing file as possible */ | |
312 | if (a_out < 0) { | |
313 | ERROR0 ("can't build a COFF file from scratch yet"); | |
314 | /*NOTREACHED*/ | |
315 | } | |
316 | ||
317 | if (read (a_out, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr)) { | |
318 | PERROR (a_name); | |
319 | } | |
320 | block_copy_start += sizeof (f_hdr); | |
321 | if (f_hdr.h_opthdr > 0) { | |
322 | if (read (a_out, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr)) { | |
323 | PERROR (a_name); | |
324 | } | |
325 | block_copy_start += sizeof (f_ohdr); | |
326 | } | |
327 | ||
328 | /* Allocate room for scn headers */ | |
329 | stbl = (struct scnhdr *)malloc( sizeof(struct scnhdr) * f_hdr.h_nscns ); | |
330 | if( stbl == NULL ) { | |
331 | ERROR0( "unexec: malloc of stbl failed" ); | |
332 | } | |
333 | ||
334 | f_tdhdr = f_tbhdr = NULL; | |
335 | ||
336 | /* Loop through section headers, copying them in */ | |
337 | for (scns = 0; scns < f_hdr.h_nscns; scns++) { | |
338 | ||
339 | if( read( a_out, &stbl[scns], sizeof(*stbl)) != sizeof(*stbl)) { | |
340 | PERROR (a_name); | |
341 | } | |
342 | ||
343 | scntype = stbl[scns].s_flags & S_TYPMASK; /* What type of section */ | |
344 | ||
345 | if( stbl[scns].s_scnptr > 0L) { | |
346 | if( block_copy_start < stbl[scns].s_scnptr + stbl[scns].s_size ) | |
347 | block_copy_start = stbl[scns].s_scnptr + stbl[scns].s_size; | |
348 | } | |
349 | ||
350 | if( scntype == S_TEXT) { | |
351 | f_thdr = &stbl[scns]; | |
352 | } else if( scntype == S_DATA) { | |
353 | f_dhdr = &stbl[scns]; | |
354 | #ifdef S_TDATA | |
355 | } else if( scntype == S_TDATA ) { | |
356 | f_tdhdr = &stbl[scns]; | |
357 | } else if( scntype == S_TBSS ) { | |
358 | f_tbhdr = &stbl[scns]; | |
359 | #endif /* S_TDATA (thread stuff) */ | |
360 | ||
361 | } else if( scntype == S_BSS) { | |
362 | f_bhdr = &stbl[scns]; | |
363 | } | |
364 | ||
365 | } | |
366 | ||
367 | /* We will now convert TEXT and DATA into TEXT, BSS into DATA, and leave | |
368 | * all thread stuff alone. | |
369 | */ | |
370 | ||
371 | /* Now we alter the contents of all the f_*hdr variables | |
372 | to correspond to what we want to dump. */ | |
373 | ||
374 | f_thdr->s_vaddr = (long) start_of_text (); | |
375 | f_thdr->s_size = data_start - f_thdr->s_vaddr; | |
376 | f_thdr->s_scnptr = pagesz; | |
377 | f_thdr->s_relptr = 0; | |
378 | f_thdr->s_nrel = 0; | |
379 | ||
380 | eo_data = f_thdr->s_scnptr + f_thdr->s_size; | |
381 | ||
382 | if( f_tdhdr ) { /* Process thread data */ | |
383 | ||
384 | f_tdhdr->s_vaddr = data_start; | |
385 | f_tdhdr->s_size += f_dhdr->s_size - (data_start - f_dhdr->s_vaddr); | |
386 | f_tdhdr->s_scnptr = eo_data; | |
387 | f_tdhdr->s_relptr = 0; | |
388 | f_tdhdr->s_nrel = 0; | |
389 | ||
390 | eo_data += f_tdhdr->s_size; | |
391 | ||
392 | /* And now for DATA */ | |
393 | ||
394 | f_dhdr->s_vaddr = f_bhdr->s_vaddr; /* Take BSS start address */ | |
395 | f_dhdr->s_size = bss_end - f_bhdr->s_vaddr; | |
396 | f_dhdr->s_scnptr = eo_data; | |
397 | f_dhdr->s_relptr = 0; | |
398 | f_dhdr->s_nrel = 0; | |
399 | ||
400 | eo_data += f_dhdr->s_size; | |
401 | ||
402 | } else { | |
403 | ||
404 | f_dhdr->s_vaddr = data_start; | |
405 | f_dhdr->s_size = bss_start - data_start; | |
406 | f_dhdr->s_scnptr = eo_data; | |
407 | f_dhdr->s_relptr = 0; | |
408 | f_dhdr->s_nrel = 0; | |
409 | ||
410 | eo_data += f_dhdr->s_size; | |
411 | ||
412 | } | |
413 | ||
414 | f_bhdr->s_vaddr = bss_start; | |
415 | f_bhdr->s_size = bss_end - bss_start + pagesz /* fudge */; | |
416 | f_bhdr->s_scnptr = 0; | |
417 | f_bhdr->s_relptr = 0; | |
418 | f_bhdr->s_nrel = 0; | |
419 | ||
420 | text_scnptr = f_thdr->s_scnptr; | |
421 | data_scnptr = f_dhdr->s_scnptr; | |
422 | bias = eo_data - block_copy_start; | |
423 | ||
424 | if (f_ohdr.o_symptr > 0L) { | |
425 | f_ohdr.o_symptr += bias; | |
426 | } | |
427 | ||
428 | if (f_hdr.h_strptr > 0) { | |
429 | f_hdr.h_strptr += bias; | |
430 | } | |
431 | ||
432 | if (write (new, &f_hdr, sizeof (f_hdr)) != sizeof (f_hdr)) { | |
433 | PERROR (new_name); | |
434 | } | |
435 | ||
436 | if (write (new, &f_ohdr, sizeof (f_ohdr)) != sizeof (f_ohdr)) { | |
437 | PERROR (new_name); | |
438 | } | |
439 | ||
440 | for( scns = 0; scns < f_hdr.h_nscns; scns++ ) { | |
441 | ||
eb8c3be9 | 442 | /* This is a cheesy little loop to write out the section headers |
d427b66a JB |
443 | * in order of increasing virtual address. Dull but effective. |
444 | */ | |
445 | ||
446 | for( i = scns+1; i < f_hdr.h_nscns; i++ ) { | |
447 | if( stbl[i].s_vaddr < stbl[scns].s_vaddr ) { /* Swap */ | |
448 | scntemp = stbl[i]; | |
449 | stbl[i] = stbl[scns]; | |
450 | stbl[scns] = scntemp; | |
451 | } | |
452 | } | |
453 | ||
454 | } | |
455 | ||
456 | for( scns = 0; scns < f_hdr.h_nscns; scns++ ) { | |
457 | ||
458 | if( write( new, &stbl[scns], sizeof(*stbl)) != sizeof(*stbl)) { | |
459 | PERROR (new_name); | |
460 | } | |
461 | ||
462 | } | |
463 | ||
464 | return (0); | |
465 | ||
466 | } | |
467 | \f | |
468 | /* **************************************************************** | |
469 | * copy_text_and_data | |
470 | * | |
471 | * Copy the text and data segments from memory to the new a.out | |
472 | */ | |
473 | static int | |
474 | copy_text_and_data (new) | |
475 | int new; | |
476 | { | |
477 | register int scns; | |
478 | ||
479 | for( scns = 0; scns < f_hdr.h_nscns; scns++ ) | |
480 | write_segment( new, &stbl[scns] ); | |
481 | ||
482 | return 0; | |
483 | } | |
484 | ||
485 | write_segment( new, sptr ) | |
486 | int new; | |
487 | struct scnhdr *sptr; | |
488 | { | |
489 | register char *ptr, *end; | |
490 | register int nwrite, ret; | |
491 | char buf[80]; | |
492 | extern int errno; | |
493 | char zeros[128]; | |
494 | ||
495 | if( sptr->s_scnptr == 0 ) | |
496 | return; /* Nothing to do */ | |
497 | ||
498 | if( lseek( new, (long) sptr->s_scnptr, 0 ) == -1 ) | |
499 | PERROR( "unexecing" ); | |
500 | ||
501 | bzero (zeros, sizeof zeros); | |
502 | ||
503 | ptr = (char *) sptr->s_vaddr; | |
504 | end = ptr + sptr->s_size; | |
505 | ||
506 | while( ptr < end ) { | |
507 | ||
508 | /* distance to next multiple of 128. */ | |
509 | nwrite = (((int) ptr + 128) & -128) - (int) ptr; | |
510 | /* But not beyond specified end. */ | |
511 | if (nwrite > end - ptr) nwrite = end - ptr; | |
512 | ret = write (new, ptr, nwrite); | |
513 | /* If write gets a page fault, it means we reached | |
514 | a gap between the old text segment and the old data segment. | |
515 | This gap has probably been remapped into part of the text segment. | |
516 | So write zeros for it. */ | |
517 | if (ret == -1 && errno == EFAULT) | |
518 | write (new, zeros, nwrite); | |
519 | else if (nwrite != ret) { | |
520 | sprintf (buf, | |
521 | "unexec write failure: addr 0x%x, fileno %d, size 0x%x, wrote 0x%x, errno %d", | |
522 | ptr, new, nwrite, ret, errno); | |
523 | PERROR (buf); | |
524 | } | |
525 | ptr += nwrite; | |
526 | } | |
527 | } | |
528 | \f | |
529 | /* **************************************************************** | |
530 | * copy_sym | |
531 | * | |
532 | * Copy the relocation information and symbol table from the a.out to the new | |
533 | */ | |
534 | static int | |
535 | copy_sym (new, a_out, a_name, new_name) | |
536 | int new, a_out; | |
537 | char *a_name, *new_name; | |
538 | { | |
539 | char page[1024]; | |
540 | int n; | |
541 | ||
542 | if (a_out < 0) | |
543 | return 0; | |
544 | ||
545 | if (SYMS_START == 0L) | |
546 | return 0; | |
547 | ||
548 | lseek (a_out, SYMS_START, 0); /* Position a.out to symtab. */ | |
549 | lseek( new, (long)f_ohdr.o_symptr, 0 ); | |
550 | ||
551 | while ((n = read (a_out, page, sizeof page)) > 0) { | |
552 | if (write (new, page, n) != n) { | |
553 | PERROR (new_name); | |
554 | } | |
555 | } | |
556 | if (n < 0) { | |
557 | PERROR (a_name); | |
558 | } | |
559 | return 0; | |
560 | } | |
561 | \f | |
562 | /* **************************************************************** | |
563 | * mark_x | |
564 | * | |
eb8c3be9 | 565 | * After successfully building the new a.out, mark it executable |
d427b66a JB |
566 | */ |
567 | static | |
568 | mark_x (name) | |
569 | char *name; | |
570 | { | |
571 | struct stat sbuf; | |
572 | int um; | |
573 | int new = 0; /* for PERROR */ | |
574 | ||
575 | um = umask (777); | |
576 | umask (um); | |
577 | if (stat (name, &sbuf) == -1) { | |
578 | PERROR (name); | |
579 | } | |
580 | sbuf.st_mode |= 0111 & ~um; | |
581 | if (chmod (name, sbuf.st_mode) == -1) | |
582 | PERROR (name); | |
583 | } | |
584 | \f | |
585 | /* Find the first pty letter. This is usually 'p', as in ptyp0, but | |
586 | is sometimes configured down to 'm', 'n', or 'o' for some reason. */ | |
587 | ||
588 | first_pty_letter () | |
589 | { | |
590 | struct stat buf; | |
591 | char pty_name[16]; | |
592 | char c; | |
593 | ||
594 | for (c = 'o'; c >= 'a'; c--) | |
595 | { | |
596 | sprintf (pty_name, "/dev/pty%c0", c); | |
597 | if (stat (pty_name, &buf) < 0) | |
598 | return c + 1; | |
599 | } | |
600 | return 'a'; | |
601 | } | |
602 |