xref: /freebsd/contrib/bc/src/vm.c (revision 2e4311906d8c8dc7a7c726345268253bca6d4acc)
1 /*
2  * *****************************************************************************
3  *
4  * SPDX-License-Identifier: BSD-2-Clause
5  *
6  * Copyright (c) 2018-2021 Gavin D. Howard and contributors.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions are met:
10  *
11  * * Redistributions of source code must retain the above copyright notice, this
12  *   list of conditions and the following disclaimer.
13  *
14  * * Redistributions in binary form must reproduce the above copyright notice,
15  *   this list of conditions and the following disclaimer in the documentation
16  *   and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
22  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28  * POSSIBILITY OF SUCH DAMAGE.
29  *
30  * *****************************************************************************
31  *
32  * Code common to all of bc and dc.
33  *
34  */
35 
36 #include <assert.h>
37 #include <ctype.h>
38 #include <errno.h>
39 #include <stdarg.h>
40 #include <string.h>
41 
42 #include <signal.h>
43 
44 #include <setjmp.h>
45 
46 #ifndef _WIN32
47 
48 #include <unistd.h>
49 #include <sys/types.h>
50 #include <unistd.h>
51 
52 #else // _WIN32
53 
54 #define WIN32_LEAN_AND_MEAN
55 #include <windows.h>
56 #include <io.h>
57 
58 #endif // _WIN32
59 
60 #include <status.h>
61 #include <vector.h>
62 #include <args.h>
63 #include <vm.h>
64 #include <read.h>
65 #include <bc.h>
66 
67 // The actual globals.
68 static BcDig* temps_buf[BC_VM_MAX_TEMPS];
69 char output_bufs[BC_VM_BUF_SIZE];
70 BcVm vm;
71 
72 #if BC_DEBUG_CODE
73 BC_NORETURN void bc_vm_jmp(const char* f) {
74 #else // BC_DEBUG_CODE
75 BC_NORETURN void bc_vm_jmp(void) {
76 #endif
77 
78 	assert(BC_SIG_EXC);
79 
80 	BC_SIG_MAYLOCK;
81 
82 #if BC_DEBUG_CODE
83 	bc_file_puts(&vm.ferr, bc_flush_none, "Longjmp: ");
84 	bc_file_puts(&vm.ferr, bc_flush_none, f);
85 	bc_file_putchar(&vm.ferr, bc_flush_none, '\n');
86 	bc_file_flush(&vm.ferr, bc_flush_none);
87 #endif // BC_DEBUG_CODE
88 
89 #ifndef NDEBUG
90 	assert(vm.jmp_bufs.len - (size_t) vm.sig_pop);
91 #endif // NDEBUG
92 
93 	if (vm.jmp_bufs.len == 0) abort();
94 	if (vm.sig_pop) bc_vec_pop(&vm.jmp_bufs);
95 	else vm.sig_pop = 1;
96 
97 	siglongjmp(*((sigjmp_buf*) bc_vec_top(&vm.jmp_bufs)), 1);
98 }
99 
100 #if !BC_ENABLE_LIBRARY
101 
102 /**
103  * Handles signals. This is the signal handler.
104  * @param sig  The signal to handle.
105  */
106 static void bc_vm_sig(int sig) {
107 
108 	// There is already a signal in flight.
109 	if (vm.status == (sig_atomic_t) BC_STATUS_QUIT || vm.sig) {
110 		if (!BC_I || sig != SIGINT) vm.status = BC_STATUS_QUIT;
111 		return;
112 	}
113 
114 	// Only reset under these conditions; otherwise, quit.
115 	if (sig == SIGINT && BC_SIGINT && BC_I) {
116 
117 		int err = errno;
118 
119 		// Write the message.
120 		if (write(STDOUT_FILENO, vm.sigmsg, vm.siglen) != (ssize_t) vm.siglen)
121 			vm.status = BC_STATUS_ERROR_FATAL;
122 		else vm.sig = 1;
123 
124 		errno = err;
125 	}
126 	else vm.status = BC_STATUS_QUIT;
127 
128 	assert(vm.jmp_bufs.len);
129 
130 	// Only jump if signals are not locked. The jump will happen by whoever
131 	// unlocks signals.
132 	if (!vm.sig_lock) BC_JMP;
133 }
134 
135 /**
136  * Sets up signal handling.
137  */
138 static void bc_vm_sigaction(void) {
139 #ifndef _WIN32
140 
141 	struct sigaction sa;
142 
143 	sigemptyset(&sa.sa_mask);
144 	sa.sa_handler = bc_vm_sig;
145 	sa.sa_flags = SA_NODEFER;
146 
147 	sigaction(SIGTERM, &sa, NULL);
148 	sigaction(SIGQUIT, &sa, NULL);
149 	sigaction(SIGINT, &sa, NULL);
150 
151 #if BC_ENABLE_HISTORY
152 	if (BC_TTY) sigaction(SIGHUP, &sa, NULL);
153 #endif // BC_ENABLE_HISTORY
154 
155 #else // _WIN32
156 
157 	signal(SIGTERM, bc_vm_sig);
158 	signal(SIGINT, bc_vm_sig);
159 
160 #endif // _WIN32
161 }
162 
163 void bc_vm_info(const char* const help) {
164 
165 	BC_SIG_ASSERT_LOCKED;
166 
167 	// Print the banner.
168 	bc_file_puts(&vm.fout, bc_flush_none, vm.name);
169 	bc_file_putchar(&vm.fout, bc_flush_none, ' ');
170 	bc_file_puts(&vm.fout, bc_flush_none, BC_VERSION);
171 	bc_file_putchar(&vm.fout, bc_flush_none, '\n');
172 	bc_file_puts(&vm.fout, bc_flush_none, bc_copyright);
173 
174 	// Print the help.
175 	if (help) {
176 
177 		bc_file_putchar(&vm.fout, bc_flush_none, '\n');
178 
179 #if BC_ENABLED
180 		if (BC_IS_BC) {
181 
182 			const char* const banner = BC_DEFAULT_BANNER ? "to" : "to not";
183 			const char* const sigint = BC_DEFAULT_SIGINT_RESET ? "to reset" :
184 			                           "to exit";
185 			const char* const tty = BC_DEFAULT_TTY_MODE ? "enabled" :
186 			                        "disabled";
187 			const char* const prompt = BC_DEFAULT_PROMPT ? "enabled" :
188 			                           "disabled";
189 			const char* const expr = BC_DEFAULT_EXPR_EXIT ? "to exit" :
190 			                           "to not exit";
191 
192 			bc_file_printf(&vm.fout, help, vm.name, vm.name, BC_VERSION,
193 			               BC_BUILD_TYPE, banner, sigint, tty, prompt, expr);
194 		}
195 #endif // BC_ENABLED
196 
197 #if DC_ENABLED
198 		if (BC_IS_DC)
199 		{
200 			const char* const sigint = DC_DEFAULT_SIGINT_RESET ? "to reset" :
201 			                           "to exit";
202 			const char* const tty = DC_DEFAULT_TTY_MODE ? "enabled" :
203 			                        "disabled";
204 			const char* const prompt = DC_DEFAULT_PROMPT ? "enabled" :
205 			                           "disabled";
206 			const char* const expr = DC_DEFAULT_EXPR_EXIT ? "to exit" :
207 			                           "to not exit";
208 
209 			bc_file_printf(&vm.fout, help, vm.name, vm.name, BC_VERSION,
210 			               BC_BUILD_TYPE, sigint, tty, prompt, expr);
211 		}
212 #endif // DC_ENABLED
213 	}
214 
215 	// Flush.
216 	bc_file_flush(&vm.fout, bc_flush_none);
217 }
218 #endif // !BC_ENABLE_LIBRARY
219 
220 #if !BC_ENABLE_LIBRARY && !BC_ENABLE_MEMCHECK
221 BC_NORETURN
222 #endif // !BC_ENABLE_LIBRARY && !BC_ENABLE_MEMCHECK
223 void bc_vm_fatalError(BcErr e) {
224 	bc_err(e);
225 #if !BC_ENABLE_LIBRARY && !BC_ENABLE_MEMCHECK
226 	BC_UNREACHABLE
227 	abort();
228 #endif // !BC_ENABLE_LIBRARY && !BC_ENABLE_MEMCHECK
229 }
230 
231 #if BC_ENABLE_LIBRARY
232 void bc_vm_handleError(BcErr e) {
233 
234 	assert(e < BC_ERR_NELEMS);
235 	assert(!vm.sig_pop);
236 
237 	BC_SIG_LOCK;
238 
239 	// If we have a normal error...
240 	if (e <= BC_ERR_MATH_DIVIDE_BY_ZERO) {
241 
242 		// Set the error.
243 		vm.err = (BclError) (e - BC_ERR_MATH_NEGATIVE +
244 		                     BCL_ERROR_MATH_NEGATIVE);
245 	}
246 	// Abort if we should.
247 	else if (vm.abrt) abort();
248 	else if (e == BC_ERR_FATAL_ALLOC_ERR) vm.err = BCL_ERROR_FATAL_ALLOC_ERR;
249 	else vm.err = BCL_ERROR_FATAL_UNKNOWN_ERR;
250 
251 	BC_JMP;
252 }
253 #else // BC_ENABLE_LIBRARY
254 void bc_vm_handleError(BcErr e, size_t line, ...) {
255 
256 	BcStatus s;
257 	va_list args;
258 	uchar id = bc_err_ids[e];
259 	const char* err_type = vm.err_ids[id];
260 	sig_atomic_t lock;
261 
262 	assert(e < BC_ERR_NELEMS);
263 	assert(!vm.sig_pop);
264 
265 #if BC_ENABLED
266 	// Figure out if the POSIX error should be an error, a warning, or nothing.
267 	if (!BC_S && e >= BC_ERR_POSIX_START) {
268 		if (BC_W) {
269 			// Make sure to not return an error.
270 			id = UCHAR_MAX;
271 			err_type = vm.err_ids[BC_ERR_IDX_WARN];
272 		}
273 		else return;
274 	}
275 #endif // BC_ENABLED
276 
277 	BC_SIG_TRYLOCK(lock);
278 
279 	// Make sure all of stdout is written first.
280 	s = bc_file_flushErr(&vm.fout, bc_flush_err);
281 
282 	// Just jump out if the flush failed; there's nothing we can do.
283 	if (BC_ERR(s == BC_STATUS_ERROR_FATAL)) {
284 		vm.status = (sig_atomic_t) s;
285 		BC_JMP;
286 	}
287 
288 	// Print the error message.
289 	va_start(args, line);
290 	bc_file_putchar(&vm.ferr, bc_flush_none, '\n');
291 	bc_file_puts(&vm.ferr, bc_flush_none, err_type);
292 	bc_file_putchar(&vm.ferr, bc_flush_none, ' ');
293 	bc_file_vprintf(&vm.ferr, vm.err_msgs[e], args);
294 	va_end(args);
295 
296 	// Print the extra information if we have it.
297 	if (BC_NO_ERR(vm.file != NULL)) {
298 
299 		// This is the condition for parsing vs runtime.
300 		// If line is not 0, it is parsing.
301 		if (line) {
302 			bc_file_puts(&vm.ferr, bc_flush_none, "\n    ");
303 			bc_file_puts(&vm.ferr, bc_flush_none, vm.file);
304 			bc_file_printf(&vm.ferr, bc_err_line, line);
305 		}
306 		else {
307 
308 			BcInstPtr *ip = bc_vec_item_rev(&vm.prog.stack, 0);
309 			BcFunc *f = bc_vec_item(&vm.prog.fns, ip->func);
310 
311 			bc_file_puts(&vm.ferr, bc_flush_none, "\n    ");
312 			bc_file_puts(&vm.ferr, bc_flush_none, vm.func_header);
313 			bc_file_putchar(&vm.ferr, bc_flush_none, ' ');
314 			bc_file_puts(&vm.ferr, bc_flush_none, f->name);
315 
316 #if BC_ENABLED
317 			if (BC_IS_BC && ip->func != BC_PROG_MAIN &&
318 			    ip->func != BC_PROG_READ)
319 			{
320 				bc_file_puts(&vm.ferr, bc_flush_none, "()");
321 			}
322 #endif // BC_ENABLED
323 		}
324 	}
325 
326 	bc_file_puts(&vm.ferr, bc_flush_none, "\n\n");
327 
328 	s = bc_file_flushErr(&vm.ferr, bc_flush_err);
329 
330 #if !BC_ENABLE_MEMCHECK
331 	// Because this function is called by a BC_NORETURN function when fatal
332 	// errors happen, we need to make sure to exit on fatal errors. This will
333 	// be faster anyway. This function *cannot jump when a fatal error occurs!*
334 	if (BC_ERR(id == BC_ERR_IDX_FATAL || s == BC_STATUS_ERROR_FATAL))
335 		exit(bc_vm_atexit((int) BC_STATUS_ERROR_FATAL));
336 #else // !BC_ENABLE_MEMCHECK
337 	if (BC_ERR(s == BC_STATUS_ERROR_FATAL)) vm.status = (sig_atomic_t) s;
338 	else
339 #endif // !BC_ENABLE_MEMCHECK
340 	{
341 		vm.status = (sig_atomic_t) (uchar) (id + 1);
342 	}
343 
344 	// Only jump if there is an error.
345 	if (BC_ERR(vm.status)) BC_JMP;
346 
347 	BC_SIG_TRYUNLOCK(lock);
348 }
349 
350 char* bc_vm_getenv(const char* var) {
351 
352 	char* ret;
353 
354 #ifndef _WIN32
355 	ret = getenv(var);
356 #else // _WIN32
357 	_dupenv_s(&ret, NULL, var);
358 #endif // _WIN32
359 
360 	return ret;
361 }
362 
363 void bc_vm_getenvFree(char* val) {
364 	BC_UNUSED(val);
365 #ifdef _WIN32
366 	free(val);
367 #endif // _WIN32
368 }
369 
370 /**
371  * Sets a flag from an environment variable and the default.
372  * @param var   The environment variable.
373  * @param def   The default.
374  * @param flag  The flag to set.
375  */
376 static void bc_vm_setenvFlag(const char* const var, int def, uint16_t flag) {
377 
378 	// Get the value.
379 	char* val = bc_vm_getenv(var);
380 
381 	// If there is no value...
382 	if (val == NULL) {
383 
384 		// Set the default.
385 		if (def) vm.flags |= flag;
386 		else vm.flags &= ~(flag);
387 	}
388 	// Parse the value.
389 	else if (strtoul(val, NULL, 0)) vm.flags |= flag;
390 	else vm.flags &= ~(flag);
391 
392 	bc_vm_getenvFree(val);
393 }
394 
395 /**
396  * Parses the arguments in {B,D]C_ENV_ARGS.
397  * @param env_args_name  The environment variable to use.
398  */
399 static void bc_vm_envArgs(const char* const env_args_name) {
400 
401 	char *env_args = bc_vm_getenv(env_args_name), *buf, *start;
402 	char instr = '\0';
403 
404 	BC_SIG_ASSERT_LOCKED;
405 
406 	if (env_args == NULL) return;
407 
408 	// Windows already allocates, so we don't need to.
409 #ifndef _WIN32
410 	start = buf = vm.env_args_buffer = bc_vm_strdup(env_args);
411 #else // _WIN32
412 	start = buf = vm.env_args_buffer = env_args;
413 #endif // _WIN32
414 
415 	assert(buf != NULL);
416 
417 	// Create two buffers for parsing. These need to stay throughout the entire
418 	// execution of bc, unfortunately, because of filenames that might be in
419 	// there.
420 	bc_vec_init(&vm.env_args, sizeof(char*), BC_DTOR_NONE);
421 	bc_vec_push(&vm.env_args, &env_args_name);
422 
423 	// While we haven't reached the end of the args...
424 	while (*buf) {
425 
426 		// If we don't have whitespace...
427 		if (!isspace(*buf)) {
428 
429 			// If we have the start of a string...
430 			if (*buf == '"' || *buf == '\'') {
431 
432 				// Set stuff appropriately.
433 				instr = *buf;
434 				buf += 1;
435 
436 				// Check for the empty string.
437 				if (*buf == instr) {
438 					instr = '\0';
439 					buf += 1;
440 					continue;
441 				}
442 			}
443 
444 			// Push the pointer to the args buffer.
445 			bc_vec_push(&vm.env_args, &buf);
446 
447 			// Parse the string.
448 			while (*buf && ((!instr && !isspace(*buf)) ||
449 			                (instr && *buf != instr)))
450 			{
451 				buf += 1;
452 			}
453 
454 			// If we did find the end of the string...
455 			if (*buf) {
456 
457 				if (instr) instr = '\0';
458 
459 				// Reset stuff.
460 				*buf = '\0';
461 				buf += 1;
462 				start = buf;
463 			}
464 			else if (instr) bc_error(BC_ERR_FATAL_OPTION, 0, start);
465 		}
466 		// If we have whitespace, eat it.
467 		else buf += 1;
468 	}
469 
470 	// Make sure to push a NULL pointer at the end.
471 	buf = NULL;
472 	bc_vec_push(&vm.env_args, &buf);
473 
474 	// Parse the arguments.
475 	bc_args((int) vm.env_args.len - 1, bc_vec_item(&vm.env_args, 0), false);
476 }
477 
478 /**
479  * Gets the {B,D}C_LINE_LENGTH.
480  * @param var  The environment variable to pull it from.
481  * @return     The line length.
482  */
483 static size_t bc_vm_envLen(const char *var) {
484 
485 	char *lenv = bc_vm_getenv(var);
486 	size_t i, len = BC_NUM_PRINT_WIDTH;
487 	int num;
488 
489 	// Return the default with none.
490 	if (lenv == NULL) return len;
491 
492 	len = strlen(lenv);
493 
494 	// Figure out if it's a number.
495 	for (num = 1, i = 0; num && i < len; ++i) num = isdigit(lenv[i]);
496 
497 	// If it is a number...
498 	if (num) {
499 
500 		// Parse it and clamp it if needed.
501 		len = (size_t) atoi(lenv) - 1;
502 		if (len == 1 || len >= UINT16_MAX) len = BC_NUM_PRINT_WIDTH;
503 	}
504 	// Set the default.
505 	else len = BC_NUM_PRINT_WIDTH;
506 
507 	bc_vm_getenvFree(lenv);
508 
509 	return len;
510 }
511 #endif // BC_ENABLE_LIBRARY
512 
513 void bc_vm_shutdown(void) {
514 
515 	BC_SIG_ASSERT_LOCKED;
516 
517 #if BC_ENABLE_NLS
518 	if (vm.catalog != BC_VM_INVALID_CATALOG) catclose(vm.catalog);
519 #endif // BC_ENABLE_NLS
520 
521 #if BC_ENABLE_HISTORY
522 	// This must always run to ensure that the terminal is back to normal, i.e.,
523 	// has raw mode disabled.
524 	if (BC_TTY) bc_history_free(&vm.history);
525 #endif // BC_ENABLE_HISTORY
526 
527 #ifndef NDEBUG
528 #if !BC_ENABLE_LIBRARY
529 	bc_vec_free(&vm.env_args);
530 	free(vm.env_args_buffer);
531 	bc_vec_free(&vm.files);
532 	bc_vec_free(&vm.exprs);
533 
534 	if (BC_PARSE_IS_INITED(&vm.read_prs, &vm.prog)) {
535 		bc_vec_free(&vm.read_buf);
536 		bc_parse_free(&vm.read_prs);
537 	}
538 
539 	bc_parse_free(&vm.prs);
540 	bc_program_free(&vm.prog);
541 
542 	bc_slabvec_free(&vm.other_slabs);
543 	bc_slabvec_free(&vm.main_slabs);
544 	bc_slabvec_free(&vm.main_const_slab);
545 #endif // !BC_ENABLE_LIBRARY
546 
547 	bc_vm_freeTemps();
548 #endif // NDEBUG
549 
550 #if !BC_ENABLE_LIBRARY
551 	// We always want to flush.
552 	bc_file_free(&vm.fout);
553 	bc_file_free(&vm.ferr);
554 #endif // !BC_ENABLE_LIBRARY
555 }
556 
557 void bc_vm_addTemp(BcDig *num) {
558 
559 	BC_SIG_ASSERT_LOCKED;
560 
561 	// If we don't have room, just free.
562 	if (vm.temps_len == BC_VM_MAX_TEMPS) free(num);
563 	else {
564 
565 		// Add to the buffer and length.
566 		temps_buf[vm.temps_len] = num;
567 		vm.temps_len += 1;
568 	}
569 }
570 
571 BcDig* bc_vm_takeTemp(void) {
572 
573 	BC_SIG_ASSERT_LOCKED;
574 
575 	if (!vm.temps_len) return NULL;
576 
577 	vm.temps_len -= 1;
578 
579 	return temps_buf[vm.temps_len];
580 }
581 
582 void bc_vm_freeTemps(void) {
583 
584 	size_t i;
585 
586 	BC_SIG_ASSERT_LOCKED;
587 
588 	if (!vm.temps_len) return;
589 
590 	// Free them all...
591 	for (i = 0; i < vm.temps_len; ++i) free(temps_buf[i]);
592 
593 	vm.temps_len = 0;
594 }
595 
596 inline size_t bc_vm_arraySize(size_t n, size_t size) {
597 	size_t res = n * size;
598 	if (BC_ERR(BC_VM_MUL_OVERFLOW(n, size, res)))
599 		bc_vm_fatalError(BC_ERR_FATAL_ALLOC_ERR);
600 	return res;
601 }
602 
603 inline size_t bc_vm_growSize(size_t a, size_t b) {
604 	size_t res = a + b;
605 	if (BC_ERR(res >= SIZE_MAX || res < a))
606 		bc_vm_fatalError(BC_ERR_FATAL_ALLOC_ERR);
607 	return res;
608 }
609 
610 void* bc_vm_malloc(size_t n) {
611 
612 	void* ptr;
613 
614 	BC_SIG_ASSERT_LOCKED;
615 
616 	ptr = malloc(n);
617 
618 	if (BC_ERR(ptr == NULL)) {
619 
620 		bc_vm_freeTemps();
621 
622 		ptr = malloc(n);
623 
624 		if (BC_ERR(ptr == NULL)) bc_vm_fatalError(BC_ERR_FATAL_ALLOC_ERR);
625 	}
626 
627 	return ptr;
628 }
629 
630 void* bc_vm_realloc(void *ptr, size_t n) {
631 
632 	void* temp;
633 
634 	BC_SIG_ASSERT_LOCKED;
635 
636 	temp = realloc(ptr, n);
637 
638 	if (BC_ERR(temp == NULL)) {
639 
640 		bc_vm_freeTemps();
641 
642 		temp = realloc(ptr, n);
643 
644 		if (BC_ERR(temp == NULL)) bc_vm_fatalError(BC_ERR_FATAL_ALLOC_ERR);
645 	}
646 
647 	return temp;
648 }
649 
650 char* bc_vm_strdup(const char *str) {
651 
652 	char *s;
653 
654 	BC_SIG_ASSERT_LOCKED;
655 
656 	s = strdup(str);
657 
658 	if (BC_ERR(s == NULL)) {
659 
660 		bc_vm_freeTemps();
661 
662 		s = strdup(str);
663 
664 		if (BC_ERR(s == NULL)) bc_vm_fatalError(BC_ERR_FATAL_ALLOC_ERR);
665 	}
666 
667 	return s;
668 }
669 
670 #if !BC_ENABLE_LIBRARY
671 void bc_vm_printf(const char *fmt, ...) {
672 
673 	va_list args;
674 	sig_atomic_t lock;
675 
676 	BC_SIG_TRYLOCK(lock);
677 
678 	va_start(args, fmt);
679 	bc_file_vprintf(&vm.fout, fmt, args);
680 	va_end(args);
681 
682 	vm.nchars = 0;
683 
684 	BC_SIG_TRYUNLOCK(lock);
685 }
686 #endif // !BC_ENABLE_LIBRARY
687 
688 void bc_vm_putchar(int c, BcFlushType type) {
689 #if BC_ENABLE_LIBRARY
690 	bc_vec_pushByte(&vm.out, (uchar) c);
691 #else // BC_ENABLE_LIBRARY
692 	bc_file_putchar(&vm.fout, type, (uchar) c);
693 	vm.nchars = (c == '\n' ? 0 : vm.nchars + 1);
694 #endif // BC_ENABLE_LIBRARY
695 }
696 
697 #if !BC_ENABLE_LIBRARY
698 
699 #ifdef __OpenBSD__
700 
701 /**
702  * Aborts with a message. This should never be called because I have carefully
703  * made sure that the calls to pledge() and unveil() are correct, but it's here
704  * just in case.
705  * @param msg  The message to print.
706  */
707 BC_NORETURN static void bc_abortm(const char* msg) {
708 	bc_file_puts(&vm.ferr, bc_flush_none, msg);
709 	bc_file_puts(&vm.ferr, bc_flush_none, "; this is a bug");
710 	bc_file_flush(&vm.ferr, bc_flush_none);
711 	abort();
712 }
713 
714 void bc_pledge(const char *promises, const char* execpromises) {
715 	int r = pledge(promises, execpromises);
716 	if (r) bc_abortm("pledge() failed");
717 }
718 
719 #if BC_ENABLE_EXTRA_MATH
720 
721 /**
722  * A convenience and portability function for OpenBSD's unveil().
723  * @param path         The path.
724  * @param permissions  The permissions for the path.
725  */
726 static void bc_unveil(const char *path, const char *permissions) {
727 	int r = unveil(path, permissions);
728 	if (r) bc_abortm("unveil() failed");
729 }
730 #endif // BC_ENABLE_EXTRA_MATH
731 
732 #else // __OpenBSD__
733 
734 void bc_pledge(const char *promises, const char *execpromises) {
735 	BC_UNUSED(promises);
736 	BC_UNUSED(execpromises);
737 }
738 
739 #if BC_ENABLE_EXTRA_MATH
740 static void bc_unveil(const char *path, const char *permissions) {
741 	BC_UNUSED(path);
742 	BC_UNUSED(permissions);
743 }
744 #endif // BC_ENABLE_EXTRA_MATH
745 
746 #endif // __OpenBSD__
747 
748 /**
749  * Cleans unneeded variables, arrays, functions, strings, and constants when
750  * done executing a line of stdin. This is to prevent memory usage growing
751  * without bound. This is an idea from busybox.
752  */
753 static void bc_vm_clean(void) {
754 
755 	BcVec *fns = &vm.prog.fns;
756 	BcFunc *f = bc_vec_item(fns, BC_PROG_MAIN);
757 	BcInstPtr *ip = bc_vec_item(&vm.prog.stack, 0);
758 	bool good = ((vm.status && vm.status != BC_STATUS_QUIT) || vm.sig);
759 
760 	BC_SIG_ASSERT_LOCKED;
761 
762 	// If all is good, go ahead and reset.
763 	if (good) bc_program_reset(&vm.prog);
764 
765 #if BC_ENABLED
766 	// bc has this extra condition. If it not satisfied, it is in the middle of
767 	// a parse.
768 	if (good && BC_IS_BC) good = !BC_PARSE_NO_EXEC(&vm.prs);
769 #endif // BC_ENABLED
770 
771 #if DC_ENABLED
772 	// For dc, it is safe only when all of the results on the results stack are
773 	// safe, which means that they are temporaries or other things that don't
774 	// need strings or constants.
775 	if (BC_IS_DC) {
776 
777 		size_t i;
778 
779 		good = true;
780 
781 		for (i = 0; good && i < vm.prog.results.len; ++i) {
782 			BcResult *r = (BcResult*) bc_vec_item(&vm.prog.results, i);
783 			good = BC_VM_SAFE_RESULT(r);
784 		}
785 	}
786 #endif // DC_ENABLED
787 
788 	// If this condition is true, we can get rid of strings,
789 	// constants, and code.
790 	if (good && vm.prog.stack.len == 1 && ip->idx == f->code.len) {
791 
792 #if BC_ENABLED
793 		if (BC_IS_BC) {
794 
795 			bc_vec_popAll(&f->labels);
796 			bc_vec_popAll(&f->strs);
797 			bc_vec_popAll(&f->consts);
798 
799 			// I can't clear out the other_slabs because it has functions,
800 			// consts, strings, vars, and arrays. It has strings from *other*
801 			// functions, specifically.
802 			bc_slabvec_clear(&vm.main_const_slab);
803 			bc_slabvec_clear(&vm.main_slabs);
804 		}
805 #endif // BC_ENABLED
806 
807 #if DC_ENABLED
808 		// Note to self: you cannot delete strings and functions. Deal with it.
809 		if (BC_IS_DC) {
810 			bc_vec_popAll(vm.prog.consts);
811 			bc_slabvec_clear(&vm.main_const_slab);
812 		}
813 #endif // DC_ENABLED
814 
815 		bc_vec_popAll(&f->code);
816 
817 		ip->idx = 0;
818 	}
819 }
820 
821 /**
822  * Process a bunch of text.
823  * @param text      The text to process.
824  * @param is_stdin  True if the text came from stdin, false otherwise.
825  */
826 static void bc_vm_process(const char *text, bool is_stdin) {
827 
828 	// Set up the parser.
829 	bc_parse_text(&vm.prs, text, is_stdin);
830 
831 	do {
832 
833 		BC_SIG_LOCK;
834 
835 #if BC_ENABLED
836 		// If the first token is the keyword define, then we need to do this
837 		// specially because bc thinks it may not be able to parse.
838 		if (vm.prs.l.t == BC_LEX_KW_DEFINE) vm.parse(&vm.prs);
839 #endif // BC_ENABLED
840 
841 		// Parse it all.
842 		while (BC_PARSE_CAN_PARSE(vm.prs)) vm.parse(&vm.prs);
843 
844 		BC_SIG_UNLOCK;
845 
846 		// Execute if possible.
847 		if(BC_IS_DC || !BC_PARSE_NO_EXEC(&vm.prs)) bc_program_exec(&vm.prog);
848 
849 		assert(BC_IS_DC || vm.prog.results.len == 0);
850 
851 		// Flush in interactive mode.
852 		if (BC_I) bc_file_flush(&vm.fout, bc_flush_save);
853 
854 	} while (vm.prs.l.t != BC_LEX_EOF);
855 }
856 
857 #if BC_ENABLED
858 
859 /**
860  * Ends a series of if statements. This is to ensure that full parses happen
861  * when a file finishes or stdin has no more data. Without this, bc thinks that
862  * it cannot parse any further. But if we reach the end of a file or stdin has
863  * no more data, we know we can add an empty else clause.
864  */
865 static void bc_vm_endif(void) {
866 	bc_parse_endif(&vm.prs);
867 	bc_program_exec(&vm.prog);
868 }
869 #endif // BC_ENABLED
870 
871 /**
872  * Processes a file.
873  * @param file  The filename.
874  */
875 static void bc_vm_file(const char *file) {
876 
877 	char *data = NULL;
878 
879 	assert(!vm.sig_pop);
880 
881 	// Set up the lexer.
882 	bc_lex_file(&vm.prs.l, file);
883 
884 	BC_SIG_LOCK;
885 
886 	// Read the file.
887 	data = bc_read_file(file);
888 
889 	assert(data != NULL);
890 
891 	BC_SETJMP_LOCKED(err);
892 
893 	BC_SIG_UNLOCK;
894 
895 	// Process it.
896 	bc_vm_process(data, false);
897 
898 #if BC_ENABLED
899 	// Make sure to end any open if statements.
900 	if (BC_IS_BC) bc_vm_endif();
901 #endif // BC_ENABLED
902 
903 err:
904 	BC_SIG_MAYLOCK;
905 
906 	// Cleanup.
907 	free(data);
908 	bc_vm_clean();
909 
910 	// bc_program_reset(), called by bc_vm_clean(), resets the status.
911 	// We want it to clear the sig_pop variable in case it was set.
912 	if (vm.status == (sig_atomic_t) BC_STATUS_SUCCESS) BC_LONGJMP_STOP;
913 
914 	BC_LONGJMP_CONT;
915 }
916 
917 bool bc_vm_readLine(bool clear) {
918 
919 	BcStatus s;
920 	bool good;
921 
922 	BC_SIG_ASSERT_NOT_LOCKED;
923 
924 	// Clear the buffer if desired.
925 	if (clear) bc_vec_empty(&vm.buffer);
926 
927 	// Empty the line buffer.
928 	bc_vec_empty(&vm.line_buf);
929 
930 	if (vm.eof) return false;
931 
932 	do {
933 		// bc_read_line() must always return either BC_STATUS_SUCCESS or
934 		// BC_STATUS_EOF. Everything else, it and whatever it calls, must jump
935 		// out instead.
936 		s = bc_read_line(&vm.line_buf, ">>> ");
937 		vm.eof = (s == BC_STATUS_EOF);
938 	} while (!(s) && !vm.eof && vm.line_buf.len < 1);
939 
940 	good = (vm.line_buf.len > 1);
941 
942 	// Concat if we found something.
943 	if (good) bc_vec_concat(&vm.buffer, vm.line_buf.v);
944 
945 	return good;
946 }
947 
948 /**
949  * Processes text from stdin.
950  */
951 static void bc_vm_stdin(void) {
952 
953 	bool clear = true;
954 
955 	vm.is_stdin = true;
956 
957 	// Set up the lexer.
958 	bc_lex_file(&vm.prs.l, bc_program_stdin_name);
959 
960 	// These are global so that the dc lexer can access them, but they are tied
961 	// to this function, really. Well, this and bc_vm_readLine(). These are the
962 	// reason that we have vm.is_stdin to tell the dc lexer if we are reading
963 	// from stdin. Well, both lexers care. And the reason they care is so that
964 	// if a comment or a string goes across multiple lines, the lexer can
965 	// request more data from stdin until the comment or string is ended.
966 	BC_SIG_LOCK;
967 	bc_vec_init(&vm.buffer, sizeof(uchar), BC_DTOR_NONE);
968 	bc_vec_init(&vm.line_buf, sizeof(uchar), BC_DTOR_NONE);
969 	BC_SETJMP_LOCKED(err);
970 	BC_SIG_UNLOCK;
971 
972 // This label exists because errors can cause jumps to end up at the err label
973 // below. If that happens, and the error should be cleared and execution
974 // continue, then we need to jump back.
975 restart:
976 
977 	// While we still read data from stdin.
978 	while (bc_vm_readLine(clear)) {
979 
980 		size_t len = vm.buffer.len - 1;
981 		const char *str = vm.buffer.v;
982 
983 		// We don't want to clear the buffer when the line ends with a backslash
984 		// because a backslash newline is special in bc.
985 		clear = (len < 2 || str[len - 2] != '\\' || str[len - 1] != '\n');
986 		if (!clear) continue;
987 
988 		// Process the data.
989 		bc_vm_process(vm.buffer.v, true);
990 
991 		if (vm.eof) break;
992 		else {
993 			BC_SIG_LOCK;
994 			bc_vm_clean();
995 			BC_SIG_UNLOCK;
996 		}
997 	}
998 
999 #if BC_ENABLED
1000 	// End the if statements.
1001 	if (BC_IS_BC) bc_vm_endif();
1002 #endif // BC_ENABLED
1003 
1004 err:
1005 	BC_SIG_MAYLOCK;
1006 
1007 	// Cleanup.
1008 	bc_vm_clean();
1009 
1010 #if !BC_ENABLE_MEMCHECK
1011 	assert(vm.status != BC_STATUS_ERROR_FATAL);
1012 
1013 	vm.status = vm.status == BC_STATUS_QUIT || !BC_I ?
1014 	            vm.status : BC_STATUS_SUCCESS;
1015 #else // !BC_ENABLE_MEMCHECK
1016 	vm.status = vm.status == BC_STATUS_ERROR_FATAL ||
1017 	            vm.status == BC_STATUS_QUIT || !BC_I ?
1018 	            vm.status : BC_STATUS_SUCCESS;
1019 #endif // !BC_ENABLE_MEMCHECK
1020 
1021 	if (!vm.status && !vm.eof) {
1022 		bc_vec_empty(&vm.buffer);
1023 		BC_LONGJMP_STOP;
1024 		BC_SIG_UNLOCK;
1025 		goto restart;
1026 	}
1027 
1028 #ifndef NDEBUG
1029 	// Since these are tied to this function, free them here.
1030 	bc_vec_free(&vm.line_buf);
1031 	bc_vec_free(&vm.buffer);
1032 #endif // NDEBUG
1033 
1034 	BC_LONGJMP_CONT;
1035 }
1036 
1037 #if BC_ENABLED
1038 
1039 /**
1040  * Loads a math library.
1041  * @param name  The name of the library.
1042  * @param text  The text of the source code.
1043  */
1044 static void bc_vm_load(const char *name, const char *text) {
1045 
1046 	bc_lex_file(&vm.prs.l, name);
1047 	bc_parse_text(&vm.prs, text, false);
1048 
1049 	BC_SIG_LOCK;
1050 
1051 	while (vm.prs.l.t != BC_LEX_EOF) vm.parse(&vm.prs);
1052 
1053 	BC_SIG_UNLOCK;
1054 }
1055 
1056 #endif // BC_ENABLED
1057 
1058 /**
1059  * Loads the default error messages.
1060  */
1061 static void bc_vm_defaultMsgs(void) {
1062 
1063 	size_t i;
1064 
1065 	vm.func_header = bc_err_func_header;
1066 
1067 	// Load the error categories.
1068 	for (i = 0; i < BC_ERR_IDX_NELEMS + BC_ENABLED; ++i)
1069 		vm.err_ids[i] = bc_errs[i];
1070 
1071 	// Load the error messages.
1072 	for (i = 0; i < BC_ERR_NELEMS; ++i) vm.err_msgs[i] = bc_err_msgs[i];
1073 }
1074 
1075 /**
1076  * Loads the error messages for the locale. If NLS is disabled, this just loads
1077  * the default messages.
1078  */
1079 static void bc_vm_gettext(void) {
1080 
1081 #if BC_ENABLE_NLS
1082 	uchar id = 0;
1083 	int set = 1, msg = 1;
1084 	size_t i;
1085 
1086 	// If no locale, load the defaults.
1087 	if (vm.locale == NULL) {
1088 		vm.catalog = BC_VM_INVALID_CATALOG;
1089 		bc_vm_defaultMsgs();
1090 		return;
1091 	}
1092 
1093 	vm.catalog = catopen(BC_MAINEXEC, NL_CAT_LOCALE);
1094 
1095 	// If no catalog, load the defaults.
1096 	if (vm.catalog == BC_VM_INVALID_CATALOG) {
1097 		bc_vm_defaultMsgs();
1098 		return;
1099 	}
1100 
1101 	// Load the function header.
1102 	vm.func_header = catgets(vm.catalog, set, msg, bc_err_func_header);
1103 
1104 	// Load the error categories.
1105 	for (set += 1; msg <= BC_ERR_IDX_NELEMS + BC_ENABLED; ++msg)
1106 		vm.err_ids[msg - 1] = catgets(vm.catalog, set, msg, bc_errs[msg - 1]);
1107 
1108 	i = 0;
1109 	id = bc_err_ids[i];
1110 
1111 	// Load the error messages. In order to understand this loop, you must know
1112 	// the order of messages and categories in the enum and in the locale files.
1113 	for (set = id + 3, msg = 1; i < BC_ERR_NELEMS; ++i, ++msg) {
1114 
1115 		if (id != bc_err_ids[i]) {
1116 			msg = 1;
1117 			id = bc_err_ids[i];
1118 			set = id + 3;
1119 		}
1120 
1121 		vm.err_msgs[i] = catgets(vm.catalog, set, msg, bc_err_msgs[i]);
1122 	}
1123 #else // BC_ENABLE_NLS
1124 	bc_vm_defaultMsgs();
1125 #endif // BC_ENABLE_NLS
1126 }
1127 
1128 /**
1129  * Starts execution. Really, this is a function of historical accident; it could
1130  * probably be combined with bc_vm_boot(), but I don't care enough. Really, this
1131  * function starts when execution of bc or dc source code starts.
1132  */
1133 static void bc_vm_exec(void) {
1134 
1135 	size_t i;
1136 	bool has_file = false;
1137 	BcVec buf;
1138 
1139 #if BC_ENABLED
1140 	// Load the math libraries.
1141 	if (BC_IS_BC && (vm.flags & BC_FLAG_L)) {
1142 
1143 		// Can't allow redefinitions in the builtin library.
1144 		vm.no_redefine = true;
1145 
1146 		bc_vm_load(bc_lib_name, bc_lib);
1147 
1148 #if BC_ENABLE_EXTRA_MATH
1149 		if (!BC_IS_POSIX) bc_vm_load(bc_lib2_name, bc_lib2);
1150 #endif // BC_ENABLE_EXTRA_MATH
1151 
1152 		// Make sure to clear this.
1153 		vm.no_redefine = false;
1154 
1155 		// Execute to ensure that all is hunky dory. Without this, scale can be
1156 		// set improperly.
1157 		bc_program_exec(&vm.prog);
1158 	}
1159 #endif // BC_ENABLED
1160 
1161 	// If there are expressions to execute...
1162 	if (vm.exprs.len) {
1163 
1164 		size_t len = vm.exprs.len - 1;
1165 		bool more;
1166 
1167 		BC_SIG_LOCK;
1168 
1169 		// Create this as a buffer for reading into.
1170 		bc_vec_init(&buf, sizeof(uchar), BC_DTOR_NONE);
1171 
1172 #ifndef NDEBUG
1173 		BC_SETJMP_LOCKED(err);
1174 #endif // NDEBUG
1175 
1176 		BC_SIG_UNLOCK;
1177 
1178 		// Prepare the lexer.
1179 		bc_lex_file(&vm.prs.l, bc_program_exprs_name);
1180 
1181 		// Process the expressions one at a time.
1182 		do {
1183 
1184 			more = bc_read_buf(&buf, vm.exprs.v, &len);
1185 			bc_vec_pushByte(&buf, '\0');
1186 			bc_vm_process(buf.v, false);
1187 
1188 			bc_vec_popAll(&buf);
1189 
1190 		} while (more);
1191 
1192 		BC_SIG_LOCK;
1193 
1194 		bc_vec_free(&buf);
1195 
1196 #ifndef NDEBUG
1197 		BC_UNSETJMP;
1198 #endif // NDEBUG
1199 
1200 		BC_SIG_UNLOCK;
1201 
1202 		// Sometimes, executing expressions means we need to quit.
1203 		if (!vm.no_exprs && vm.exit_exprs && BC_EXPR_EXIT) return;
1204 	}
1205 
1206 	// Process files.
1207 	for (i = 0; i < vm.files.len; ++i) {
1208 		char *path = *((char**) bc_vec_item(&vm.files, i));
1209 		if (!strcmp(path, "")) continue;
1210 		has_file = true;
1211 		bc_vm_file(path);
1212 	}
1213 
1214 #if BC_ENABLE_EXTRA_MATH
1215 	// These are needed for the pseudo-random number generator.
1216 	bc_unveil("/dev/urandom", "r");
1217 	bc_unveil("/dev/random", "r");
1218 	bc_unveil(NULL, NULL);
1219 #endif // BC_ENABLE_EXTRA_MATH
1220 
1221 #if BC_ENABLE_HISTORY
1222 
1223 	// We need to keep tty if history is enabled, and we need to keep rpath for
1224 	// the times when we read from /dev/urandom.
1225 	if (BC_TTY && !vm.history.badTerm) bc_pledge(bc_pledge_end_history, NULL);
1226 	else
1227 #endif // BC_ENABLE_HISTORY
1228 	{
1229 		bc_pledge(bc_pledge_end, NULL);
1230 	}
1231 
1232 #if BC_ENABLE_AFL
1233 	// This is the thing that makes fuzzing with AFL++ so fast. If you move this
1234 	// back, you won't cause any problems, but fuzzing will slow down. If you
1235 	// move this forward, you won't fuzz anything because you will be skipping
1236 	// the reading from stdin.
1237 	__AFL_INIT();
1238 #endif // BC_ENABLE_AFL
1239 
1240 	// Execute from stdin. bc always does.
1241 	if (BC_IS_BC || !has_file) bc_vm_stdin();
1242 
1243 // These are all protected by ifndef NDEBUG because if these are needed, bc is
1244 // going to exit anyway, and I see no reason to include this code in a release
1245 // build when the OS is going to free all of the resources anyway.
1246 #ifndef NDEBUG
1247 	return;
1248 
1249 err:
1250 	BC_SIG_MAYLOCK;
1251 	bc_vec_free(&buf);
1252 	BC_LONGJMP_CONT;
1253 #endif // NDEBUG
1254 }
1255 
1256 void bc_vm_boot(int argc, char *argv[]) {
1257 
1258 	int ttyin, ttyout, ttyerr;
1259 	bool tty;
1260 	const char* const env_len = BC_IS_BC ? "BC_LINE_LENGTH" : "DC_LINE_LENGTH";
1261 	const char* const env_args = BC_IS_BC ? "BC_ENV_ARGS" : "DC_ENV_ARGS";
1262 	const char* const env_exit = BC_IS_BC ? "BC_EXPR_EXIT" : "DC_EXPR_EXIT";
1263 	int env_exit_def = BC_IS_BC ? BC_DEFAULT_EXPR_EXIT : DC_DEFAULT_EXPR_EXIT;
1264 
1265 	// We need to know which of stdin, stdout, and stderr are tty's.
1266 	ttyin = isatty(STDIN_FILENO);
1267 	ttyout = isatty(STDOUT_FILENO);
1268 	ttyerr = isatty(STDERR_FILENO);
1269 	tty = (ttyin != 0 && ttyout != 0 && ttyerr != 0);
1270 
1271 	vm.flags |= ttyin ? BC_FLAG_TTYIN : 0;
1272 	vm.flags |= tty ? BC_FLAG_TTY : 0;
1273 	vm.flags |= ttyin && ttyout ? BC_FLAG_I : 0;
1274 
1275 	// Set up signals.
1276 	bc_vm_sigaction();
1277 
1278 	// Initialize some vm stuff. This is separate to make things easier for the
1279 	// library.
1280 	bc_vm_init();
1281 
1282 	// Explicitly set this in case NULL isn't all zeroes.
1283 	vm.file = NULL;
1284 
1285 	// Set the error messages.
1286 	bc_vm_gettext();
1287 
1288 	// Initialize the output file buffers. They each take portions of the global
1289 	// buffer. stdout gets more because it will probably have more data.
1290 	bc_file_init(&vm.ferr, STDERR_FILENO, output_bufs + BC_VM_STDOUT_BUF_SIZE,
1291 	             BC_VM_STDERR_BUF_SIZE);
1292 	bc_file_init(&vm.fout, STDOUT_FILENO, output_bufs, BC_VM_STDOUT_BUF_SIZE);
1293 
1294 	// Set the input buffer to the rest of the global buffer.
1295 	vm.buf = output_bufs + BC_VM_STDOUT_BUF_SIZE + BC_VM_STDERR_BUF_SIZE;
1296 
1297 	// Set the line length by environment variable.
1298 	vm.line_len = (uint16_t) bc_vm_envLen(env_len);
1299 
1300 	bc_vm_setenvFlag(env_exit, env_exit_def, BC_FLAG_EXPR_EXIT);
1301 
1302 	// Clear the files and expressions vectors, just in case. This marks them as
1303 	// *not* allocated.
1304 	bc_vec_clear(&vm.files);
1305 	bc_vec_clear(&vm.exprs);
1306 
1307 #if !BC_ENABLE_LIBRARY
1308 
1309 	// Initialize the slab vectors.
1310 	bc_slabvec_init(&vm.main_const_slab);
1311 	bc_slabvec_init(&vm.main_slabs);
1312 	bc_slabvec_init(&vm.other_slabs);
1313 
1314 #endif // !BC_ENABLE_LIBRARY
1315 
1316 	// Initialize the program and main parser. These have to be in this order
1317 	// because the program has to be initialized first, since a pointer to it is
1318 	// passed to the parser.
1319 	bc_program_init(&vm.prog);
1320 	bc_parse_init(&vm.prs, &vm.prog, BC_PROG_MAIN);
1321 
1322 	// Set defaults.
1323 	vm.flags |= BC_TTY ? BC_FLAG_P | BC_FLAG_R : 0;
1324 	vm.flags |= BC_I ? BC_FLAG_Q : 0;
1325 
1326 #if BC_ENABLED
1327 	if (BC_IS_BC) {
1328 
1329 		// bc checks this environment variable to see if it should run in
1330 		// standard mode.
1331 		char* var = bc_vm_getenv("POSIXLY_CORRECT");
1332 
1333 		vm.flags |= BC_FLAG_S * (var != NULL);
1334 		bc_vm_getenvFree(var);
1335 
1336 		// Set whether we print the banner or not.
1337 		if (BC_I) bc_vm_setenvFlag("BC_BANNER", BC_DEFAULT_BANNER, BC_FLAG_Q);
1338 	}
1339 #endif // BC_ENABLED
1340 
1341 	// Are we in TTY mode?
1342 	if (BC_TTY) {
1343 
1344 		const char* const env_tty = BC_IS_BC ? "BC_TTY_MODE" : "DC_TTY_MODE";
1345 		int env_tty_def = BC_IS_BC ? BC_DEFAULT_TTY_MODE : DC_DEFAULT_TTY_MODE;
1346 		const char* const env_prompt = BC_IS_BC ? "BC_PROMPT" : "DC_PROMPT";
1347 		int env_prompt_def = BC_IS_BC ? BC_DEFAULT_PROMPT : DC_DEFAULT_PROMPT;
1348 
1349 		// Set flags for TTY mode and prompt.
1350 		bc_vm_setenvFlag(env_tty, env_tty_def, BC_FLAG_TTY);
1351 		bc_vm_setenvFlag(env_prompt, tty ? env_prompt_def : 0, BC_FLAG_P);
1352 
1353 #if BC_ENABLE_HISTORY
1354 		// If TTY mode is used, activate history.
1355 		if (BC_TTY) bc_history_init(&vm.history);
1356 #endif // BC_ENABLE_HISTORY
1357 	}
1358 
1359 	// Process environment and command-line arguments.
1360 	bc_vm_envArgs(env_args);
1361 	bc_args(argc, argv, true);
1362 
1363 	// If we are in interactive mode...
1364 	if (BC_I) {
1365 
1366 		const char* const env_sigint = BC_IS_BC ? "BC_SIGINT_RESET" :
1367 		                                          "DC_SIGINT_RESET";
1368 		int env_sigint_def = BC_IS_BC ? BC_DEFAULT_SIGINT_RESET :
1369 		                                DC_DEFAULT_SIGINT_RESET;
1370 
1371 		// Set whether we reset on SIGINT or not.
1372 		bc_vm_setenvFlag(env_sigint, env_sigint_def, BC_FLAG_SIGINT);
1373 	}
1374 
1375 #if BC_ENABLED
1376 	// Disable global stacks in POSIX mode.
1377 	if (BC_IS_POSIX) vm.flags &= ~(BC_FLAG_G);
1378 
1379 	// Print the banner if allowed. We have to be in bc, in interactive mode,
1380 	// and not be quieted by command-line option or environment variable.
1381 	if (BC_IS_BC && BC_I && (vm.flags & BC_FLAG_Q)) {
1382 		bc_vm_info(NULL);
1383 		bc_file_putchar(&vm.fout, bc_flush_none, '\n');
1384 		bc_file_flush(&vm.fout, bc_flush_none);
1385 	}
1386 #endif // BC_ENABLED
1387 
1388 	BC_SIG_UNLOCK;
1389 
1390 	// Start executing.
1391 	bc_vm_exec();
1392 }
1393 #endif // !BC_ENABLE_LIBRARY
1394 
1395 void bc_vm_init(void) {
1396 
1397 	BC_SIG_ASSERT_LOCKED;
1398 
1399 #if !BC_ENABLE_LIBRARY
1400 	// Set up the constant zero.
1401 	bc_num_setup(&vm.zero, vm.zero_num, BC_VM_ONE_CAP);
1402 #endif // !BC_ENABLE_LIBRARY
1403 
1404 	// Set up more constant BcNum's.
1405 	bc_num_setup(&vm.one, vm.one_num, BC_VM_ONE_CAP);
1406 	bc_num_one(&vm.one);
1407 
1408 	// Set up more constant BcNum's.
1409 	memcpy(vm.max_num, bc_num_bigdigMax,
1410 	       bc_num_bigdigMax_size * sizeof(BcDig));
1411 	memcpy(vm.max2_num, bc_num_bigdigMax2,
1412 	       bc_num_bigdigMax2_size * sizeof(BcDig));
1413 	bc_num_setup(&vm.max, vm.max_num, BC_NUM_BIGDIG_LOG10);
1414 	bc_num_setup(&vm.max2, vm.max2_num, BC_NUM_BIGDIG_LOG10);
1415 	vm.max.len = bc_num_bigdigMax_size;
1416 	vm.max2.len = bc_num_bigdigMax2_size;
1417 
1418 	// Set up the maxes for the globals.
1419 	vm.maxes[BC_PROG_GLOBALS_IBASE] = BC_NUM_MAX_POSIX_IBASE;
1420 	vm.maxes[BC_PROG_GLOBALS_OBASE] = BC_MAX_OBASE;
1421 	vm.maxes[BC_PROG_GLOBALS_SCALE] = BC_MAX_SCALE;
1422 
1423 #if BC_ENABLE_EXTRA_MATH
1424 	vm.maxes[BC_PROG_MAX_RAND] = ((BcRand) 0) - 1;
1425 #endif // BC_ENABLE_EXTRA_MATH
1426 
1427 #if BC_ENABLED
1428 #if !BC_ENABLE_LIBRARY
1429 	// bc has a higher max ibase when it's not in POSIX mode.
1430 	if (BC_IS_BC && !BC_IS_POSIX)
1431 #endif // !BC_ENABLE_LIBRARY
1432 	{
1433 		vm.maxes[BC_PROG_GLOBALS_IBASE] = BC_NUM_MAX_IBASE;
1434 	}
1435 #endif // BC_ENABLED
1436 }
1437 
1438 #if BC_ENABLE_LIBRARY
1439 void bc_vm_atexit(void) {
1440 
1441 	bc_vm_shutdown();
1442 
1443 #ifndef NDEBUG
1444 	bc_vec_free(&vm.jmp_bufs);
1445 #endif // NDEBUG
1446 }
1447 #else // BC_ENABLE_LIBRARY
1448 int bc_vm_atexit(int status) {
1449 
1450 	// Set the status correctly.
1451 	int s = BC_STATUS_IS_ERROR(status) ? status : BC_STATUS_SUCCESS;
1452 
1453 	bc_vm_shutdown();
1454 
1455 #ifndef NDEBUG
1456 	bc_vec_free(&vm.jmp_bufs);
1457 #endif // NDEBUG
1458 
1459 	return s;
1460 }
1461 #endif // BC_ENABLE_LIBRARY
1462