1/* Demangler for the Rust programming language
2 Copyright (C) 2016-2025 Free Software Foundation, Inc.
3 Written by David Tolnay (dtolnay@gmail.com).
4 Rewritten by Eduard-Mihai Burtescu (eddyb@lyken.rs) for v0 support.
5
6This file is part of the libiberty library.
7Libiberty is free software; you can redistribute it and/or
8modify it under the terms of the GNU Library General Public
9License as published by the Free Software Foundation; either
10version 2 of the License, or (at your option) any later version.
11
12In addition to the permissions in the GNU Library General Public
13License, the Free Software Foundation gives you unlimited permission
14to link the compiled version of this file into combinations with other
15programs, and to distribute those combinations without any restriction
16coming from the use of this file. (The Library Public License
17restrictions do apply in other respects; for example, they cover
18modification of the file, and distribution when not linked into a
19combined executable.)
20
21Libiberty is distributed in the hope that it will be useful,
22but WITHOUT ANY WARRANTY; without even the implied warranty of
23MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
24Library General Public License for more details.
25
26You should have received a copy of the GNU Library General Public
27License along with libiberty; see the file COPYING.LIB.
28If not, see <http://www.gnu.org/licenses/>. */
29
30
31#ifdef HAVE_CONFIG_H
32#include "config.h"
33#endif
34
35#include "safe-ctype.h"
36
37#include <inttypes.h>
38#include <sys/types.h>
39#include <string.h>
40#include <stdio.h>
41#include <stdlib.h>
42
43#ifdef HAVE_STRING_H
44#include <string.h>
45#else
46extern size_t strlen(const char *s);
47extern int strncmp(const char *s1, const char *s2, size_t n);
48extern void *memset(void *s, int c, size_t n);
49#endif
50
51#include <demangle.h>
52#include "libiberty.h"
53
54struct rust_demangler
55{
56 const char *sym;
57 size_t sym_len;
58
59 void *callback_opaque;
60 demangle_callbackref callback;
61
62 /* Position of the next character to read from the symbol. */
63 size_t next;
64
65 /* Non-zero if any error occurred. */
66 int errored;
67
68 /* Non-zero if nothing should be printed. */
69 int skipping_printing;
70
71 /* Non-zero if printing should be verbose (e.g. include hashes). */
72 int verbose;
73
74 /* Rust mangling version, with legacy mangling being -1. */
75 int version;
76
77 /* Recursion depth. */
78 unsigned int recursion;
79 /* Maximum number of times demangle_path may be called recursively. */
80#define RUST_MAX_RECURSION_COUNT 1024
81#define RUST_NO_RECURSION_LIMIT ((unsigned int) -1)
82
83 uint64_t bound_lifetime_depth;
84};
85
86/* Parsing functions. */
87
88static char
89peek (const struct rust_demangler *rdm)
90{
91 if (rdm->next < rdm->sym_len)
92 return rdm->sym[rdm->next];
93 return 0;
94}
95
96static int
97eat (struct rust_demangler *rdm, char c)
98{
99 if (peek (rdm) == c)
100 {
101 rdm->next++;
102 return 1;
103 }
104 else
105 return 0;
106}
107
108static char
109next (struct rust_demangler *rdm)
110{
111 char c = peek (rdm);
112 if (!c)
113 rdm->errored = 1;
114 else
115 rdm->next++;
116 return c;
117}
118
119static uint64_t
120parse_integer_62 (struct rust_demangler *rdm)
121{
122 char c;
123 uint64_t x;
124
125 if (eat (rdm, c: '_'))
126 return 0;
127
128 x = 0;
129 while (!eat (rdm, c: '_') && !rdm->errored)
130 {
131 c = next (rdm);
132 x *= 62;
133 if (ISDIGIT (c))
134 x += c - '0';
135 else if (ISLOWER (c))
136 x += 10 + (c - 'a');
137 else if (ISUPPER (c))
138 x += 10 + 26 + (c - 'A');
139 else
140 {
141 rdm->errored = 1;
142 return 0;
143 }
144 }
145 return x + 1;
146}
147
148static uint64_t
149parse_opt_integer_62 (struct rust_demangler *rdm, char tag)
150{
151 if (!eat (rdm, c: tag))
152 return 0;
153 return 1 + parse_integer_62 (rdm);
154}
155
156static uint64_t
157parse_disambiguator (struct rust_demangler *rdm)
158{
159 return parse_opt_integer_62 (rdm, tag: 's');
160}
161
162static size_t
163parse_hex_nibbles (struct rust_demangler *rdm, uint64_t *value)
164{
165 char c;
166 size_t hex_len;
167
168 hex_len = 0;
169 *value = 0;
170
171 while (!eat (rdm, c: '_'))
172 {
173 *value <<= 4;
174
175 c = next (rdm);
176 if (ISDIGIT (c))
177 *value |= c - '0';
178 else if (c >= 'a' && c <= 'f')
179 *value |= 10 + (c - 'a');
180 else
181 {
182 rdm->errored = 1;
183 return 0;
184 }
185 hex_len++;
186 }
187
188 return hex_len;
189}
190
191struct rust_mangled_ident
192{
193 /* ASCII part of the identifier. */
194 const char *ascii;
195 size_t ascii_len;
196
197 /* Punycode insertion codes for Unicode codepoints, if any. */
198 const char *punycode;
199 size_t punycode_len;
200};
201
202static struct rust_mangled_ident
203parse_ident (struct rust_demangler *rdm)
204{
205 char c;
206 size_t start, len;
207 int is_punycode = 0;
208 struct rust_mangled_ident ident;
209
210 ident.ascii = NULL;
211 ident.ascii_len = 0;
212 ident.punycode = NULL;
213 ident.punycode_len = 0;
214
215 if (rdm->version != -1)
216 is_punycode = eat (rdm, c: 'u');
217
218 c = next (rdm);
219 if (!ISDIGIT (c))
220 {
221 rdm->errored = 1;
222 return ident;
223 }
224 len = c - '0';
225
226 if (c != '0')
227 while (ISDIGIT (peek (rdm)))
228 len = len * 10 + (next (rdm) - '0');
229
230 /* Skip past the optional `_` separator (v0). */
231 if (rdm->version != -1)
232 eat (rdm, c: '_');
233
234 start = rdm->next;
235 rdm->next += len;
236 /* Check for overflows. */
237 if ((start > rdm->next) || (rdm->next > rdm->sym_len))
238 {
239 rdm->errored = 1;
240 return ident;
241 }
242
243 ident.ascii = rdm->sym + start;
244 ident.ascii_len = len;
245
246 if (is_punycode)
247 {
248 ident.punycode_len = 0;
249 while (ident.ascii_len > 0)
250 {
251 ident.ascii_len--;
252
253 /* The last '_' is a separator between ascii & punycode. */
254 if (ident.ascii[ident.ascii_len] == '_')
255 break;
256
257 ident.punycode_len++;
258 }
259 if (!ident.punycode_len)
260 {
261 rdm->errored = 1;
262 return ident;
263 }
264 ident.punycode = ident.ascii + (len - ident.punycode_len);
265 }
266
267 if (ident.ascii_len == 0)
268 ident.ascii = NULL;
269
270 return ident;
271}
272
273/* Printing functions. */
274
275static void
276print_str (struct rust_demangler *rdm, const char *data, size_t len)
277{
278 if (!rdm->errored && !rdm->skipping_printing)
279 rdm->callback (data, len, rdm->callback_opaque);
280}
281
282#define PRINT(s) print_str (rdm, s, strlen (s))
283
284static void
285print_uint64 (struct rust_demangler *rdm, uint64_t x)
286{
287 char s[21];
288 snprintf (s: s, maxlen: 21, format: "%" PRIu64, x);
289 PRINT (s);
290}
291
292static void
293print_uint64_hex (struct rust_demangler *rdm, uint64_t x)
294{
295 char s[17];
296 snprintf (s: s, maxlen: 17, format: "%" PRIx64, x);
297 PRINT (s);
298}
299
300/* Return a 0x0-0xf value if the char is 0-9a-f, and -1 otherwise. */
301static int
302decode_lower_hex_nibble (char nibble)
303{
304 if ('0' <= nibble && nibble <= '9')
305 return nibble - '0';
306 if ('a' <= nibble && nibble <= 'f')
307 return 0xa + (nibble - 'a');
308 return -1;
309}
310
311/* Return the unescaped character for a "$...$" escape, or 0 if invalid. */
312static char
313decode_legacy_escape (const char *e, size_t len, size_t *out_len)
314{
315 char c = 0;
316 size_t escape_len = 0;
317 int lo_nibble = -1, hi_nibble = -1;
318
319 if (len < 3 || e[0] != '$')
320 return 0;
321
322 e++;
323 len--;
324
325 if (e[0] == 'C')
326 {
327 escape_len = 1;
328
329 c = ',';
330 }
331 else if (len > 2)
332 {
333 escape_len = 2;
334
335 if (e[0] == 'S' && e[1] == 'P')
336 c = '@';
337 else if (e[0] == 'B' && e[1] == 'P')
338 c = '*';
339 else if (e[0] == 'R' && e[1] == 'F')
340 c = '&';
341 else if (e[0] == 'L' && e[1] == 'T')
342 c = '<';
343 else if (e[0] == 'G' && e[1] == 'T')
344 c = '>';
345 else if (e[0] == 'L' && e[1] == 'P')
346 c = '(';
347 else if (e[0] == 'R' && e[1] == 'P')
348 c = ')';
349 else if (e[0] == 'u' && len > 3)
350 {
351 escape_len = 3;
352
353 hi_nibble = decode_lower_hex_nibble (nibble: e[1]);
354 if (hi_nibble < 0)
355 return 0;
356 lo_nibble = decode_lower_hex_nibble (nibble: e[2]);
357 if (lo_nibble < 0)
358 return 0;
359
360 /* Only allow non-control ASCII characters. */
361 if (hi_nibble > 7)
362 return 0;
363 c = (hi_nibble << 4) | lo_nibble;
364 if (c < 0x20)
365 return 0;
366 }
367 }
368
369 if (!c || len <= escape_len || e[escape_len] != '$')
370 return 0;
371
372 *out_len = 2 + escape_len;
373 return c;
374}
375
376static void
377print_ident (struct rust_demangler *rdm, struct rust_mangled_ident ident)
378{
379 char unescaped;
380 uint8_t *out, *p, d;
381 size_t len, cap, punycode_pos, j;
382 /* Punycode parameters and state. */
383 uint32_t c;
384 size_t base, t_min, t_max, skew, damp, bias, i;
385 size_t delta, w, k, t;
386
387 if (rdm->errored || rdm->skipping_printing)
388 return;
389
390 if (rdm->version == -1)
391 {
392 /* Ignore leading underscores preceding escape sequences.
393 The mangler inserts an underscore to make sure the
394 identifier begins with a XID_Start character. */
395 if (ident.ascii_len >= 2 && ident.ascii[0] == '_'
396 && ident.ascii[1] == '$')
397 {
398 ident.ascii++;
399 ident.ascii_len--;
400 }
401
402 while (ident.ascii_len > 0)
403 {
404 /* Handle legacy escape sequences ("$...$", ".." or "."). */
405 if (ident.ascii[0] == '$')
406 {
407 unescaped
408 = decode_legacy_escape (e: ident.ascii, len: ident.ascii_len, out_len: &len);
409 if (unescaped)
410 print_str (rdm, data: &unescaped, len: 1);
411 else
412 {
413 /* Unexpected escape sequence, print the rest verbatim. */
414 print_str (rdm, data: ident.ascii, len: ident.ascii_len);
415 return;
416 }
417 }
418 else if (ident.ascii[0] == '.')
419 {
420 if (ident.ascii_len >= 2 && ident.ascii[1] == '.')
421 {
422 /* ".." becomes "::" */
423 PRINT ("::");
424 len = 2;
425 }
426 else
427 {
428 PRINT (".");
429 len = 1;
430 }
431 }
432 else
433 {
434 /* Print everything before the next escape sequence, at once. */
435 for (len = 0; len < ident.ascii_len; len++)
436 if (ident.ascii[len] == '$' || ident.ascii[len] == '.')
437 break;
438
439 print_str (rdm, data: ident.ascii, len);
440 }
441
442 ident.ascii += len;
443 ident.ascii_len -= len;
444 }
445
446 return;
447 }
448
449 if (!ident.punycode)
450 {
451 print_str (rdm, data: ident.ascii, len: ident.ascii_len);
452 return;
453 }
454
455 len = 0;
456 cap = 4;
457 while (cap < ident.ascii_len)
458 {
459 cap *= 2;
460 /* Check for overflows. */
461 if ((cap * 4) / 4 != cap)
462 {
463 rdm->errored = 1;
464 return;
465 }
466 }
467
468 /* Store the output codepoints as groups of 4 UTF-8 bytes. */
469 out = (uint8_t *)malloc (size: cap * 4);
470 if (!out)
471 {
472 rdm->errored = 1;
473 return;
474 }
475
476 /* Populate initial output from ASCII fragment. */
477 for (len = 0; len < ident.ascii_len; len++)
478 {
479 p = out + 4 * len;
480 p[0] = 0;
481 p[1] = 0;
482 p[2] = 0;
483 p[3] = ident.ascii[len];
484 }
485
486 /* Punycode parameters and initial state. */
487 base = 36;
488 t_min = 1;
489 t_max = 26;
490 skew = 38;
491 damp = 700;
492 bias = 72;
493 i = 0;
494 c = 0x80;
495
496 punycode_pos = 0;
497 while (punycode_pos < ident.punycode_len)
498 {
499 /* Read one delta value. */
500 delta = 0;
501 w = 1;
502 k = 0;
503 do
504 {
505 k += base;
506 t = k < bias ? 0 : (k - bias);
507 if (t < t_min)
508 t = t_min;
509 if (t > t_max)
510 t = t_max;
511
512 if (punycode_pos >= ident.punycode_len)
513 goto cleanup;
514 d = ident.punycode[punycode_pos++];
515
516 if (ISLOWER (d))
517 d = d - 'a';
518 else if (ISDIGIT (d))
519 d = 26 + (d - '0');
520 else
521 {
522 rdm->errored = 1;
523 goto cleanup;
524 }
525
526 delta += d * w;
527 w *= base - t;
528 }
529 while (d >= t);
530
531 /* Compute the new insert position and character. */
532 len++;
533 i += delta;
534 c += i / len;
535 i %= len;
536
537 /* Ensure enough space is available. */
538 if (cap < len)
539 {
540 cap *= 2;
541 /* Check for overflows. */
542 if ((cap * 4) / 4 != cap || cap < len)
543 {
544 rdm->errored = 1;
545 goto cleanup;
546 }
547 }
548 p = (uint8_t *)realloc (ptr: out, size: cap * 4);
549 if (!p)
550 {
551 rdm->errored = 1;
552 goto cleanup;
553 }
554 out = p;
555
556 /* Move the characters after the insert position. */
557 p = out + i * 4;
558 memmove (dest: p + 4, src: p, n: (len - i - 1) * 4);
559
560 /* Insert the new character, as UTF-8 bytes. */
561 p[0] = c >= 0x10000 ? 0xf0 | (c >> 18) : 0;
562 p[1] = c >= 0x800 ? (c < 0x10000 ? 0xe0 : 0x80) | ((c >> 12) & 0x3f) : 0;
563 p[2] = (c < 0x800 ? 0xc0 : 0x80) | ((c >> 6) & 0x3f);
564 p[3] = 0x80 | (c & 0x3f);
565
566 /* If there are no more deltas, decoding is complete. */
567 if (punycode_pos == ident.punycode_len)
568 break;
569
570 i++;
571
572 /* Perform bias adaptation. */
573 delta /= damp;
574 damp = 2;
575
576 delta += delta / len;
577 k = 0;
578 while (delta > ((base - t_min) * t_max) / 2)
579 {
580 delta /= base - t_min;
581 k += base;
582 }
583 bias = k + ((base - t_min + 1) * delta) / (delta + skew);
584 }
585
586 /* Remove all the 0 bytes to leave behind an UTF-8 string. */
587 for (i = 0, j = 0; i < len * 4; i++)
588 if (out[i] != 0)
589 out[j++] = out[i];
590
591 print_str (rdm, data: (const char *)out, len: j);
592
593cleanup:
594 free (ptr: out);
595}
596
597/* Print the lifetime according to the previously decoded index.
598 An index of `0` always refers to `'_`, but starting with `1`,
599 indices refer to late-bound lifetimes introduced by a binder. */
600static void
601print_lifetime_from_index (struct rust_demangler *rdm, uint64_t lt)
602{
603 char c;
604 uint64_t depth;
605
606 PRINT ("'");
607 if (lt == 0)
608 {
609 PRINT ("_");
610 return;
611 }
612
613 depth = rdm->bound_lifetime_depth - lt;
614 /* Try to print lifetimes alphabetically first. */
615 if (depth < 26)
616 {
617 c = 'a' + depth;
618 print_str (rdm, data: &c, len: 1);
619 }
620 else
621 {
622 /* Use `'_123` after running out of letters. */
623 PRINT ("_");
624 print_uint64 (rdm, x: depth);
625 }
626}
627
628/* Demangling functions. */
629
630static void demangle_binder (struct rust_demangler *rdm);
631static void demangle_path (struct rust_demangler *rdm, int in_value);
632static void demangle_generic_arg (struct rust_demangler *rdm);
633static void demangle_type (struct rust_demangler *rdm);
634static int demangle_path_maybe_open_generics (struct rust_demangler *rdm);
635static void demangle_dyn_trait (struct rust_demangler *rdm);
636static void demangle_const (struct rust_demangler *rdm);
637static void demangle_const_uint (struct rust_demangler *rdm);
638static void demangle_const_int (struct rust_demangler *rdm);
639static void demangle_const_bool (struct rust_demangler *rdm);
640static void demangle_const_char (struct rust_demangler *rdm);
641
642/* Optionally enter a binder ('G') for late-bound lifetimes,
643 printing e.g. `for<'a, 'b> `, and make those lifetimes visible
644 to the caller (via depth level, which the caller should reset). */
645static void
646demangle_binder (struct rust_demangler *rdm)
647{
648 uint64_t i, bound_lifetimes;
649
650 if (rdm->errored)
651 return;
652
653 bound_lifetimes = parse_opt_integer_62 (rdm, tag: 'G');
654 if (bound_lifetimes > 0)
655 {
656 PRINT ("for<");
657 for (i = 0; i < bound_lifetimes; i++)
658 {
659 if (i > 0)
660 PRINT (", ");
661 rdm->bound_lifetime_depth++;
662 print_lifetime_from_index (rdm, lt: 1);
663 }
664 PRINT ("> ");
665 }
666}
667
668static void
669demangle_path (struct rust_demangler *rdm, int in_value)
670{
671 char tag, ns;
672 int was_skipping_printing;
673 size_t i, backref, old_next;
674 uint64_t dis;
675 struct rust_mangled_ident name;
676
677 if (rdm->errored)
678 return;
679
680 if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
681 {
682 ++ rdm->recursion;
683 if (rdm->recursion > RUST_MAX_RECURSION_COUNT)
684 /* FIXME: There ought to be a way to report
685 that the recursion limit has been reached. */
686 goto fail_return;
687 }
688
689 switch (tag = next (rdm))
690 {
691 case 'C':
692 dis = parse_disambiguator (rdm);
693 name = parse_ident (rdm);
694
695 print_ident (rdm, ident: name);
696 if (rdm->verbose)
697 {
698 PRINT ("[");
699 print_uint64_hex (rdm, x: dis);
700 PRINT ("]");
701 }
702 break;
703 case 'N':
704 ns = next (rdm);
705 if (!ISLOWER (ns) && !ISUPPER (ns))
706 goto fail_return;
707
708 demangle_path (rdm, in_value);
709
710 dis = parse_disambiguator (rdm);
711 name = parse_ident (rdm);
712
713 if (ISUPPER (ns))
714 {
715 /* Special namespaces, like closures and shims. */
716 PRINT ("::{");
717 switch (ns)
718 {
719 case 'C':
720 PRINT ("closure");
721 break;
722 case 'S':
723 PRINT ("shim");
724 break;
725 default:
726 print_str (rdm, data: &ns, len: 1);
727 }
728 if (name.ascii || name.punycode)
729 {
730 PRINT (":");
731 print_ident (rdm, ident: name);
732 }
733 PRINT ("#");
734 print_uint64 (rdm, x: dis);
735 PRINT ("}");
736 }
737 else
738 {
739 /* Implementation-specific/unspecified namespaces. */
740
741 if (name.ascii || name.punycode)
742 {
743 PRINT ("::");
744 print_ident (rdm, ident: name);
745 }
746 }
747 break;
748 case 'M':
749 case 'X':
750 /* Ignore the `impl`'s own path.*/
751 parse_disambiguator (rdm);
752 was_skipping_printing = rdm->skipping_printing;
753 rdm->skipping_printing = 1;
754 demangle_path (rdm, in_value);
755 rdm->skipping_printing = was_skipping_printing;
756 /* fallthrough */
757 case 'Y':
758 PRINT ("<");
759 demangle_type (rdm);
760 if (tag != 'M')
761 {
762 PRINT (" as ");
763 demangle_path (rdm, in_value: 0);
764 }
765 PRINT (">");
766 break;
767 case 'I':
768 demangle_path (rdm, in_value);
769 if (in_value)
770 PRINT ("::");
771 PRINT ("<");
772 for (i = 0; !rdm->errored && !eat (rdm, c: 'E'); i++)
773 {
774 if (i > 0)
775 PRINT (", ");
776 demangle_generic_arg (rdm);
777 }
778 PRINT (">");
779 break;
780 case 'B':
781 backref = parse_integer_62 (rdm);
782 if (!rdm->skipping_printing)
783 {
784 old_next = rdm->next;
785 rdm->next = backref;
786 demangle_path (rdm, in_value);
787 rdm->next = old_next;
788 }
789 break;
790 default:
791 goto fail_return;
792 }
793 goto pass_return;
794
795 fail_return:
796 rdm->errored = 1;
797 pass_return:
798 if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
799 -- rdm->recursion;
800}
801
802static void
803demangle_generic_arg (struct rust_demangler *rdm)
804{
805 uint64_t lt;
806 if (eat (rdm, c: 'L'))
807 {
808 lt = parse_integer_62 (rdm);
809 print_lifetime_from_index (rdm, lt);
810 }
811 else if (eat (rdm, c: 'K'))
812 demangle_const (rdm);
813 else
814 demangle_type (rdm);
815}
816
817static const char *
818basic_type (char tag)
819{
820 switch (tag)
821 {
822 case 'b':
823 return "bool";
824 case 'c':
825 return "char";
826 case 'e':
827 return "str";
828 case 'u':
829 return "()";
830 case 'a':
831 return "i8";
832 case 's':
833 return "i16";
834 case 'l':
835 return "i32";
836 case 'x':
837 return "i64";
838 case 'n':
839 return "i128";
840 case 'i':
841 return "isize";
842 case 'h':
843 return "u8";
844 case 't':
845 return "u16";
846 case 'm':
847 return "u32";
848 case 'y':
849 return "u64";
850 case 'o':
851 return "u128";
852 case 'j':
853 return "usize";
854 case 'f':
855 return "f32";
856 case 'd':
857 return "f64";
858 case 'z':
859 return "!";
860 case 'p':
861 return "_";
862 case 'v':
863 return "...";
864
865 default:
866 return NULL;
867 }
868}
869
870static void
871demangle_type (struct rust_demangler *rdm)
872{
873 char tag;
874 size_t i, old_next, backref;
875 uint64_t lt, old_bound_lifetime_depth;
876 const char *basic;
877 struct rust_mangled_ident abi;
878
879 if (rdm->errored)
880 return;
881
882 tag = next (rdm);
883
884 basic = basic_type (tag);
885 if (basic)
886 {
887 PRINT (basic);
888 return;
889 }
890
891 if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
892 {
893 ++ rdm->recursion;
894 if (rdm->recursion > RUST_MAX_RECURSION_COUNT)
895 /* FIXME: There ought to be a way to report
896 that the recursion limit has been reached. */
897 {
898 rdm->errored = 1;
899 -- rdm->recursion;
900 return;
901 }
902 }
903
904 switch (tag)
905 {
906 case 'R':
907 case 'Q':
908 PRINT ("&");
909 if (eat (rdm, c: 'L'))
910 {
911 lt = parse_integer_62 (rdm);
912 if (lt)
913 {
914 print_lifetime_from_index (rdm, lt);
915 PRINT (" ");
916 }
917 }
918 if (tag != 'R')
919 PRINT ("mut ");
920 demangle_type (rdm);
921 break;
922 case 'P':
923 case 'O':
924 PRINT ("*");
925 if (tag != 'P')
926 PRINT ("mut ");
927 else
928 PRINT ("const ");
929 demangle_type (rdm);
930 break;
931 case 'A':
932 case 'S':
933 PRINT ("[");
934 demangle_type (rdm);
935 if (tag == 'A')
936 {
937 PRINT ("; ");
938 demangle_const (rdm);
939 }
940 PRINT ("]");
941 break;
942 case 'T':
943 PRINT ("(");
944 for (i = 0; !rdm->errored && !eat (rdm, c: 'E'); i++)
945 {
946 if (i > 0)
947 PRINT (", ");
948 demangle_type (rdm);
949 }
950 if (i == 1)
951 PRINT (",");
952 PRINT (")");
953 break;
954 case 'F':
955 old_bound_lifetime_depth = rdm->bound_lifetime_depth;
956 demangle_binder (rdm);
957
958 if (eat (rdm, c: 'U'))
959 PRINT ("unsafe ");
960
961 if (eat (rdm, c: 'K'))
962 {
963 if (eat (rdm, c: 'C'))
964 {
965 abi.ascii = "C";
966 abi.ascii_len = 1;
967 }
968 else
969 {
970 abi = parse_ident (rdm);
971 if (!abi.ascii || abi.punycode)
972 {
973 rdm->errored = 1;
974 goto restore;
975 }
976 }
977
978 PRINT ("extern \"");
979
980 /* If the ABI had any `-`, they were replaced with `_`,
981 so the parts between `_` have to be re-joined with `-`. */
982 for (i = 0; i < abi.ascii_len; i++)
983 {
984 if (abi.ascii[i] == '_')
985 {
986 print_str (rdm, data: abi.ascii, len: i);
987 PRINT ("-");
988 abi.ascii += i + 1;
989 abi.ascii_len -= i + 1;
990 i = 0;
991 }
992 }
993 print_str (rdm, data: abi.ascii, len: abi.ascii_len);
994
995 PRINT ("\" ");
996 }
997
998 PRINT ("fn(");
999 for (i = 0; !rdm->errored && !eat (rdm, c: 'E'); i++)
1000 {
1001 if (i > 0)
1002 PRINT (", ");
1003 demangle_type (rdm);
1004 }
1005 PRINT (")");
1006
1007 if (eat (rdm, c: 'u'))
1008 {
1009 /* Skip printing the return type if it's 'u', i.e. `()`. */
1010 }
1011 else
1012 {
1013 PRINT (" -> ");
1014 demangle_type (rdm);
1015 }
1016
1017 /* Restore `bound_lifetime_depth` to outside the binder. */
1018 restore:
1019 rdm->bound_lifetime_depth = old_bound_lifetime_depth;
1020 break;
1021 case 'D':
1022 PRINT ("dyn ");
1023
1024 old_bound_lifetime_depth = rdm->bound_lifetime_depth;
1025 demangle_binder (rdm);
1026
1027 for (i = 0; !rdm->errored && !eat (rdm, c: 'E'); i++)
1028 {
1029 if (i > 0)
1030 PRINT (" + ");
1031 demangle_dyn_trait (rdm);
1032 }
1033
1034 /* Restore `bound_lifetime_depth` to outside the binder. */
1035 rdm->bound_lifetime_depth = old_bound_lifetime_depth;
1036
1037 if (!eat (rdm, c: 'L'))
1038 {
1039 rdm->errored = 1;
1040 return;
1041 }
1042 lt = parse_integer_62 (rdm);
1043 if (lt)
1044 {
1045 PRINT (" + ");
1046 print_lifetime_from_index (rdm, lt);
1047 }
1048 break;
1049 case 'B':
1050 backref = parse_integer_62 (rdm);
1051 if (!rdm->skipping_printing)
1052 {
1053 old_next = rdm->next;
1054 rdm->next = backref;
1055 demangle_type (rdm);
1056 rdm->next = old_next;
1057 }
1058 break;
1059 default:
1060 /* Go back to the tag, so `demangle_path` also sees it. */
1061 rdm->next--;
1062 demangle_path (rdm, in_value: 0);
1063 }
1064
1065 if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
1066 -- rdm->recursion;
1067}
1068
1069/* A trait in a trait object may have some "existential projections"
1070 (i.e. associated type bindings) after it, which should be printed
1071 in the `<...>` of the trait, e.g. `dyn Trait<T, U, Assoc=X>`.
1072 To this end, this method will keep the `<...>` of an 'I' path
1073 open, by omitting the `>`, and return `Ok(true)` in that case. */
1074static int
1075demangle_path_maybe_open_generics (struct rust_demangler *rdm)
1076{
1077 int open;
1078 size_t i, old_next, backref;
1079
1080 open = 0;
1081
1082 if (rdm->errored)
1083 return open;
1084
1085 if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
1086 {
1087 ++ rdm->recursion;
1088 if (rdm->recursion > RUST_MAX_RECURSION_COUNT)
1089 {
1090 /* FIXME: There ought to be a way to report
1091 that the recursion limit has been reached. */
1092 rdm->errored = 1;
1093 goto end_of_func;
1094 }
1095 }
1096
1097 if (eat (rdm, c: 'B'))
1098 {
1099 backref = parse_integer_62 (rdm);
1100 if (!rdm->skipping_printing)
1101 {
1102 old_next = rdm->next;
1103 rdm->next = backref;
1104 open = demangle_path_maybe_open_generics (rdm);
1105 rdm->next = old_next;
1106 }
1107 }
1108 else if (eat (rdm, c: 'I'))
1109 {
1110 demangle_path (rdm, in_value: 0);
1111 PRINT ("<");
1112 open = 1;
1113 for (i = 0; !rdm->errored && !eat (rdm, c: 'E'); i++)
1114 {
1115 if (i > 0)
1116 PRINT (", ");
1117 demangle_generic_arg (rdm);
1118 }
1119 }
1120 else
1121 demangle_path (rdm, in_value: 0);
1122
1123 end_of_func:
1124 if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
1125 -- rdm->recursion;
1126
1127 return open;
1128}
1129
1130static void
1131demangle_dyn_trait (struct rust_demangler *rdm)
1132{
1133 int open;
1134 struct rust_mangled_ident name;
1135
1136 if (rdm->errored)
1137 return;
1138
1139 open = demangle_path_maybe_open_generics (rdm);
1140
1141 while (eat (rdm, c: 'p'))
1142 {
1143 if (!open)
1144 PRINT ("<");
1145 else
1146 PRINT (", ");
1147 open = 1;
1148
1149 name = parse_ident (rdm);
1150 print_ident (rdm, ident: name);
1151 PRINT (" = ");
1152 demangle_type (rdm);
1153 }
1154
1155 if (open)
1156 PRINT (">");
1157}
1158
1159static void
1160demangle_const (struct rust_demangler *rdm)
1161{
1162 char ty_tag;
1163 size_t old_next, backref;
1164
1165 if (rdm->errored)
1166 return;
1167
1168 if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
1169 {
1170 ++ rdm->recursion;
1171 if (rdm->recursion > RUST_MAX_RECURSION_COUNT)
1172 /* FIXME: There ought to be a way to report
1173 that the recursion limit has been reached. */
1174 goto fail_return;
1175 }
1176
1177 if (eat (rdm, c: 'B'))
1178 {
1179 backref = parse_integer_62 (rdm);
1180 if (!rdm->skipping_printing)
1181 {
1182 old_next = rdm->next;
1183 rdm->next = backref;
1184 demangle_const (rdm);
1185 rdm->next = old_next;
1186 }
1187 goto pass_return;
1188 }
1189
1190 ty_tag = next (rdm);
1191 switch (ty_tag)
1192 {
1193 /* Placeholder. */
1194 case 'p':
1195 PRINT ("_");
1196 goto pass_return;
1197
1198 /* Unsigned integer types. */
1199 case 'h':
1200 case 't':
1201 case 'm':
1202 case 'y':
1203 case 'o':
1204 case 'j':
1205 demangle_const_uint (rdm);
1206 break;
1207
1208 /* Signed integer types. */
1209 case 'a':
1210 case 's':
1211 case 'l':
1212 case 'x':
1213 case 'n':
1214 case 'i':
1215 demangle_const_int (rdm);
1216 break;
1217
1218 /* Boolean. */
1219 case 'b':
1220 demangle_const_bool (rdm);
1221 break;
1222
1223 /* Character. */
1224 case 'c':
1225 demangle_const_char (rdm);
1226 break;
1227
1228 default:
1229 goto fail_return;
1230 }
1231
1232 if (!rdm->errored && rdm->verbose)
1233 {
1234 PRINT (": ");
1235 PRINT (basic_type (ty_tag));
1236 }
1237 goto pass_return;
1238
1239 fail_return:
1240 rdm->errored = 1;
1241 pass_return:
1242 if (rdm->recursion != RUST_NO_RECURSION_LIMIT)
1243 -- rdm->recursion;
1244}
1245
1246static void
1247demangle_const_uint (struct rust_demangler *rdm)
1248{
1249 size_t hex_len;
1250 uint64_t value;
1251
1252 if (rdm->errored)
1253 return;
1254
1255 hex_len = parse_hex_nibbles (rdm, value: &value);
1256
1257 if (hex_len > 16)
1258 {
1259 /* Print anything that doesn't fit in `uint64_t` verbatim. */
1260 PRINT ("0x");
1261 print_str (rdm, data: rdm->sym + (rdm->next - hex_len), len: hex_len);
1262 }
1263 else if (hex_len > 0)
1264 print_uint64 (rdm, x: value);
1265 else
1266 rdm->errored = 1;
1267}
1268
1269static void
1270demangle_const_int (struct rust_demangler *rdm)
1271{
1272 if (eat (rdm, c: 'n'))
1273 PRINT ("-");
1274 demangle_const_uint (rdm);
1275}
1276
1277static void
1278demangle_const_bool (struct rust_demangler *rdm)
1279{
1280 uint64_t value;
1281
1282 if (parse_hex_nibbles (rdm, value: &value) != 1)
1283 {
1284 rdm->errored = 1;
1285 return;
1286 }
1287
1288 if (value == 0)
1289 PRINT ("false");
1290 else if (value == 1)
1291 PRINT ("true");
1292 else
1293 rdm->errored = 1;
1294}
1295
1296static void
1297demangle_const_char (struct rust_demangler *rdm)
1298{
1299 size_t hex_len;
1300 uint64_t value;
1301
1302 hex_len = parse_hex_nibbles (rdm, value: &value);
1303
1304 if (hex_len == 0 || hex_len > 8)
1305 {
1306 rdm->errored = 1;
1307 return;
1308 }
1309
1310 /* Match Rust's character "debug" output as best as we can. */
1311 PRINT ("'");
1312 if (value == '\t')
1313 PRINT ("\\t");
1314 else if (value == '\r')
1315 PRINT ("\\r");
1316 else if (value == '\n')
1317 PRINT ("\\n");
1318 else if (value > ' ' && value < '~')
1319 {
1320 /* Rust also considers many non-ASCII codepoints to be printable, but
1321 that logic is not easily ported to C. */
1322 char c = value;
1323 print_str (rdm, data: &c, len: 1);
1324 }
1325 else
1326 {
1327 PRINT ("\\u{");
1328 print_uint64_hex (rdm, x: value);
1329 PRINT ("}");
1330 }
1331 PRINT ("'");
1332}
1333
1334/* A legacy hash is the prefix "h" followed by 16 lowercase hex digits.
1335 The hex digits must contain at least 5 distinct digits. */
1336static int
1337is_legacy_prefixed_hash (struct rust_mangled_ident ident)
1338{
1339 uint16_t seen;
1340 int nibble;
1341 size_t i, count;
1342
1343 if (ident.ascii_len != 17 || ident.ascii[0] != 'h')
1344 return 0;
1345
1346 seen = 0;
1347 for (i = 0; i < 16; i++)
1348 {
1349 nibble = decode_lower_hex_nibble (nibble: ident.ascii[1 + i]);
1350 if (nibble < 0)
1351 return 0;
1352 seen |= (uint16_t)1 << nibble;
1353 }
1354
1355 /* Count how many distinct digits were seen. */
1356 count = 0;
1357 while (seen)
1358 {
1359 if (seen & 1)
1360 count++;
1361 seen >>= 1;
1362 }
1363
1364 return count >= 5;
1365}
1366
1367int
1368rust_demangle_callback (const char *mangled, int options,
1369 demangle_callbackref callback, void *opaque)
1370{
1371 const char *p;
1372 struct rust_demangler rdm;
1373 struct rust_mangled_ident ident;
1374
1375 rdm.sym = mangled;
1376 rdm.sym_len = 0;
1377
1378 rdm.callback_opaque = opaque;
1379 rdm.callback = callback;
1380
1381 rdm.next = 0;
1382 rdm.errored = 0;
1383 rdm.skipping_printing = 0;
1384 rdm.verbose = (options & DMGL_VERBOSE) != 0;
1385 rdm.version = 0;
1386 rdm.recursion = (options & DMGL_NO_RECURSE_LIMIT) ? RUST_NO_RECURSION_LIMIT : 0;
1387 rdm.bound_lifetime_depth = 0;
1388
1389 /* Rust symbols always start with _R (v0) or _ZN (legacy). */
1390 if (rdm.sym[0] == '_' && rdm.sym[1] == 'R')
1391 rdm.sym += 2;
1392 else if (rdm.sym[0] == '_' && rdm.sym[1] == 'Z' && rdm.sym[2] == 'N')
1393 {
1394 rdm.sym += 3;
1395 rdm.version = -1;
1396 }
1397 else
1398 return 0;
1399
1400 /* Paths (v0) always start with uppercase characters. */
1401 if (rdm.version != -1 && !ISUPPER (rdm.sym[0]))
1402 return 0;
1403
1404 /* Rust symbols (v0) use only [_0-9a-zA-Z] characters. */
1405 for (p = rdm.sym; *p; p++)
1406 {
1407 /* Rust v0 symbols can have '.' suffixes, ignore those. */
1408 if (rdm.version == 0 && *p == '.')
1409 break;
1410
1411 rdm.sym_len++;
1412
1413 if (*p == '_' || ISALNUM (*p))
1414 continue;
1415
1416 /* Legacy Rust symbols can also contain [.:$] characters.
1417 Or @ in the .suffix (which will be skipped, see below). */
1418 if (rdm.version == -1 && (*p == '$' || *p == '.' || *p == ':'
1419 || *p == '@'))
1420 continue;
1421
1422 return 0;
1423 }
1424
1425 /* Legacy Rust symbols need to be handled separately. */
1426 if (rdm.version == -1)
1427 {
1428 /* Legacy Rust symbols always end with E. But can be followed by a
1429 .suffix (which we want to ignore). */
1430 int dot_suffix = 1;
1431 while (rdm.sym_len > 0 &&
1432 !(dot_suffix && rdm.sym[rdm.sym_len - 1] == 'E'))
1433 {
1434 dot_suffix = rdm.sym[rdm.sym_len - 1] == '.';
1435 rdm.sym_len--;
1436 }
1437
1438 if (!(rdm.sym_len > 0 && rdm.sym[rdm.sym_len - 1] == 'E'))
1439 return 0;
1440 rdm.sym_len--;
1441
1442 /* Legacy Rust symbols also always end with a path segment
1443 that encodes a 16 hex digit hash, i.e. '17h[a-f0-9]{16}'.
1444 This early check, before any parse_ident calls, should
1445 quickly filter out most C++ symbols unrelated to Rust. */
1446 if (!(rdm.sym_len > 19
1447 && !memcmp (s1: &rdm.sym[rdm.sym_len - 19], s2: "17h", n: 3)))
1448 return 0;
1449
1450 do
1451 {
1452 ident = parse_ident (rdm: &rdm);
1453 if (rdm.errored || !ident.ascii)
1454 return 0;
1455 }
1456 while (rdm.next < rdm.sym_len);
1457
1458 /* The last path segment should be the hash. */
1459 if (!is_legacy_prefixed_hash (ident))
1460 return 0;
1461
1462 /* Reset the state for a second pass, to print the symbol. */
1463 rdm.next = 0;
1464 if (!rdm.verbose && rdm.sym_len > 19)
1465 {
1466 /* Hide the last segment, containing the hash, if not verbose. */
1467 rdm.sym_len -= 19;
1468 }
1469
1470 do
1471 {
1472 if (rdm.next > 0)
1473 print_str (rdm: &rdm, data: "::", len: 2);
1474
1475 ident = parse_ident (rdm: &rdm);
1476 print_ident (rdm: &rdm, ident);
1477 }
1478 while (rdm.next < rdm.sym_len);
1479 }
1480 else
1481 {
1482 demangle_path (rdm: &rdm, in_value: 1);
1483
1484 /* Skip instantiating crate. */
1485 if (!rdm.errored && rdm.next < rdm.sym_len)
1486 {
1487 rdm.skipping_printing = 1;
1488 demangle_path (rdm: &rdm, in_value: 0);
1489 }
1490
1491 /* It's an error to not reach the end. */
1492 rdm.errored |= rdm.next != rdm.sym_len;
1493 }
1494
1495 return !rdm.errored;
1496}
1497
1498/* Growable string buffers. */
1499struct str_buf
1500{
1501 char *ptr;
1502 size_t len;
1503 size_t cap;
1504 int errored;
1505};
1506
1507static void
1508str_buf_reserve (struct str_buf *buf, size_t extra)
1509{
1510 size_t available, min_new_cap, new_cap;
1511 char *new_ptr;
1512
1513 /* Allocation failed before. */
1514 if (buf->errored)
1515 return;
1516
1517 available = buf->cap - buf->len;
1518
1519 if (extra <= available)
1520 return;
1521
1522 min_new_cap = buf->cap + (extra - available);
1523
1524 /* Check for overflows. */
1525 if (min_new_cap < buf->cap)
1526 {
1527 buf->errored = 1;
1528 return;
1529 }
1530
1531 new_cap = buf->cap;
1532
1533 if (new_cap == 0)
1534 new_cap = 4;
1535
1536 /* Double capacity until sufficiently large. */
1537 while (new_cap < min_new_cap)
1538 {
1539 new_cap *= 2;
1540
1541 /* Check for overflows. */
1542 if (new_cap < buf->cap)
1543 {
1544 buf->errored = 1;
1545 return;
1546 }
1547 }
1548
1549 new_ptr = (char *)realloc (ptr: buf->ptr, size: new_cap);
1550 if (new_ptr == NULL)
1551 {
1552 free (ptr: buf->ptr);
1553 buf->ptr = NULL;
1554 buf->len = 0;
1555 buf->cap = 0;
1556 buf->errored = 1;
1557 }
1558 else
1559 {
1560 buf->ptr = new_ptr;
1561 buf->cap = new_cap;
1562 }
1563}
1564
1565static void
1566str_buf_append (struct str_buf *buf, const char *data, size_t len)
1567{
1568 str_buf_reserve (buf, extra: len);
1569 if (buf->errored)
1570 return;
1571
1572 memcpy (dest: buf->ptr + buf->len, src: data, n: len);
1573 buf->len += len;
1574}
1575
1576static void
1577str_buf_demangle_callback (const char *data, size_t len, void *opaque)
1578{
1579 str_buf_append (buf: (struct str_buf *)opaque, data, len);
1580}
1581
1582char *
1583rust_demangle (const char *mangled, int options)
1584{
1585 struct str_buf out;
1586 int success;
1587
1588 out.ptr = NULL;
1589 out.len = 0;
1590 out.cap = 0;
1591 out.errored = 0;
1592
1593 success = rust_demangle_callback (mangled, options,
1594 callback: str_buf_demangle_callback, opaque: &out);
1595
1596 if (!success)
1597 {
1598 free (ptr: out.ptr);
1599 return NULL;
1600 }
1601
1602 str_buf_append (buf: &out, data: "\0", len: 1);
1603 return out.ptr;
1604}
1605

source code of libiberty/rust-demangle.c