349 lines
9.8 KiB
C
349 lines
9.8 KiB
C
/* Demangler for the Rust programming language
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Copyright (C) 2016-2017 Free Software Foundation, Inc.
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Written by David Tolnay (dtolnay@gmail.com).
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This file is part of the libiberty library.
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Libiberty is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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In addition to the permissions in the GNU Library General Public
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License, the Free Software Foundation gives you unlimited permission
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to link the compiled version of this file into combinations with other
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programs, and to distribute those combinations without any restriction
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coming from the use of this file. (The Library Public License
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restrictions do apply in other respects; for example, they cover
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modification of the file, and distribution when not linked into a
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combined executable.)
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Libiberty is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with libiberty; see the file COPYING.LIB.
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If not, see <http://www.gnu.org/licenses/>. */
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "safe-ctype.h"
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#include <sys/types.h>
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#include <string.h>
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#include <stdio.h>
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#ifdef HAVE_STRING_H
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#include <string.h>
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#else
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extern size_t strlen(const char *s);
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extern int strncmp(const char *s1, const char *s2, size_t n);
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extern void *memset(void *s, int c, size_t n);
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#endif
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#include <demangle.h>
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#include "libiberty.h"
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/* Mangled Rust symbols look like this:
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_$LT$std..sys..fd..FileDesc$u20$as$u20$core..ops..Drop$GT$::drop::hc68340e1baa4987a
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The original symbol is:
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<std::sys::fd::FileDesc as core::ops::Drop>::drop
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The last component of the path is a 64-bit hash in lowercase hex,
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prefixed with "h". Rust does not have a global namespace between
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crates, an illusion which Rust maintains by using the hash to
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distinguish things that would otherwise have the same symbol.
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Any path component not starting with a XID_Start character is
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prefixed with "_".
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The following escape sequences are used:
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"," => $C$
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"@" => $SP$
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"*" => $BP$
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"&" => $RF$
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"<" => $LT$
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">" => $GT$
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"(" => $LP$
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")" => $RP$
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" " => $u20$
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"\"" => $u22$
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"'" => $u27$
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"+" => $u2b$
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";" => $u3b$
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"[" => $u5b$
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"]" => $u5d$
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"{" => $u7b$
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"}" => $u7d$
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"~" => $u7e$
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A double ".." means "::" and a single "." means "-".
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The only characters allowed in the mangled symbol are a-zA-Z0-9 and _.:$ */
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static const char *hash_prefix = "::h";
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static const size_t hash_prefix_len = 3;
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static const size_t hash_len = 16;
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static int is_prefixed_hash (const char *start);
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static int looks_like_rust (const char *sym, size_t len);
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static int unescape (const char **in, char **out, const char *seq, char value);
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/* INPUT: sym: symbol that has been through C++ (gnu v3) demangling
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This function looks for the following indicators:
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1. The hash must consist of "h" followed by 16 lowercase hex digits.
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2. As a sanity check, the hash must use between 5 and 15 of the 16
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possible hex digits. This is true of 99.9998% of hashes so once
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in your life you may see a false negative. The point is to
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notice path components that could be Rust hashes but are
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probably not, like "haaaaaaaaaaaaaaaa". In this case a false
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positive (non-Rust symbol has an important path component
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removed because it looks like a Rust hash) is worse than a false
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negative (the rare Rust symbol is not demangled) so this sets
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the balance in favor of false negatives.
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3. There must be no characters other than a-zA-Z0-9 and _.:$
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4. There must be no unrecognized $-sign sequences.
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5. There must be no sequence of three or more dots in a row ("..."). */
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int
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rust_is_mangled (const char *sym)
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{
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size_t len, len_without_hash;
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if (!sym)
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return 0;
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len = strlen (sym);
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if (len <= hash_prefix_len + hash_len)
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/* Not long enough to contain "::h" + hash + something else */
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return 0;
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len_without_hash = len - (hash_prefix_len + hash_len);
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if (!is_prefixed_hash (sym + len_without_hash))
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return 0;
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return looks_like_rust (sym, len_without_hash);
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}
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/* A hash is the prefix "::h" followed by 16 lowercase hex digits. The
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hex digits must comprise between 5 and 15 (inclusive) distinct
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digits. */
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static int
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is_prefixed_hash (const char *str)
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{
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const char *end;
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char seen[16];
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size_t i;
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int count;
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if (strncmp (str, hash_prefix, hash_prefix_len))
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return 0;
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str += hash_prefix_len;
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memset (seen, 0, sizeof(seen));
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for (end = str + hash_len; str < end; str++)
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if (*str >= '0' && *str <= '9')
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seen[*str - '0'] = 1;
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else if (*str >= 'a' && *str <= 'f')
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seen[*str - 'a' + 10] = 1;
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else
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return 0;
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/* Count how many distinct digits seen */
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count = 0;
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for (i = 0; i < 16; i++)
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if (seen[i])
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count++;
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return count >= 5 && count <= 15;
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}
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static int
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looks_like_rust (const char *str, size_t len)
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{
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const char *end = str + len;
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while (str < end)
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switch (*str)
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{
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case '$':
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if (!strncmp (str, "$C$", 3))
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str += 3;
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else if (!strncmp (str, "$SP$", 4)
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|| !strncmp (str, "$BP$", 4)
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|| !strncmp (str, "$RF$", 4)
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|| !strncmp (str, "$LT$", 4)
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|| !strncmp (str, "$GT$", 4)
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|| !strncmp (str, "$LP$", 4)
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|| !strncmp (str, "$RP$", 4))
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str += 4;
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else if (!strncmp (str, "$u20$", 5)
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|| !strncmp (str, "$u22$", 5)
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|| !strncmp (str, "$u27$", 5)
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|| !strncmp (str, "$u2b$", 5)
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|| !strncmp (str, "$u3b$", 5)
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|| !strncmp (str, "$u5b$", 5)
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|| !strncmp (str, "$u5d$", 5)
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|| !strncmp (str, "$u7b$", 5)
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|| !strncmp (str, "$u7d$", 5)
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|| !strncmp (str, "$u7e$", 5))
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str += 5;
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else
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return 0;
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break;
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case '.':
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/* Do not allow three or more consecutive dots */
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if (!strncmp (str, "...", 3))
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return 0;
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/* Fall through */
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case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
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case 'g': case 'h': case 'i': case 'j': case 'k': case 'l':
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case 'm': case 'n': case 'o': case 'p': case 'q': case 'r':
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case 's': case 't': case 'u': case 'v': case 'w': case 'x':
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case 'y': case 'z':
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case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
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case 'G': case 'H': case 'I': case 'J': case 'K': case 'L':
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case 'M': case 'N': case 'O': case 'P': case 'Q': case 'R':
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case 'S': case 'T': case 'U': case 'V': case 'W': case 'X':
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case 'Y': case 'Z':
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case '0': case '1': case '2': case '3': case '4': case '5':
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case '6': case '7': case '8': case '9':
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case '_':
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case ':':
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str++;
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break;
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default:
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return 0;
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}
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return 1;
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}
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/*
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INPUT: sym: symbol for which rust_is_mangled(sym) returned 1.
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The input is demangled in-place because the mangled name is always
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longer than the demangled one. */
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void
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rust_demangle_sym (char *sym)
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{
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const char *in;
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char *out;
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const char *end;
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if (!sym)
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return;
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in = sym;
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out = sym;
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end = sym + strlen (sym) - (hash_prefix_len + hash_len);
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while (in < end)
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switch (*in)
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{
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case '$':
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if (!(unescape (&in, &out, "$C$", ',')
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|| unescape (&in, &out, "$SP$", '@')
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|| unescape (&in, &out, "$BP$", '*')
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|| unescape (&in, &out, "$RF$", '&')
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|| unescape (&in, &out, "$LT$", '<')
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|| unescape (&in, &out, "$GT$", '>')
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|| unescape (&in, &out, "$LP$", '(')
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|| unescape (&in, &out, "$RP$", ')')
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|| unescape (&in, &out, "$u20$", ' ')
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|| unescape (&in, &out, "$u22$", '\"')
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|| unescape (&in, &out, "$u27$", '\'')
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|| unescape (&in, &out, "$u2b$", '+')
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|| unescape (&in, &out, "$u3b$", ';')
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|| unescape (&in, &out, "$u5b$", '[')
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|| unescape (&in, &out, "$u5d$", ']')
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|| unescape (&in, &out, "$u7b$", '{')
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|| unescape (&in, &out, "$u7d$", '}')
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|| unescape (&in, &out, "$u7e$", '~'))) {
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/* unexpected escape sequence, not looks_like_rust. */
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goto fail;
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}
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break;
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case '_':
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/* If this is the start of a path component and the next
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character is an escape sequence, ignore the underscore. The
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mangler inserts an underscore to make sure the path
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component begins with a XID_Start character. */
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if ((in == sym || in[-1] == ':') && in[1] == '$')
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in++;
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else
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*out++ = *in++;
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break;
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case '.':
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if (in[1] == '.')
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{
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/* ".." becomes "::" */
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*out++ = ':';
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*out++ = ':';
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in += 2;
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}
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else
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{
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/* "." becomes "-" */
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*out++ = '-';
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in++;
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}
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break;
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case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
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case 'g': case 'h': case 'i': case 'j': case 'k': case 'l':
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case 'm': case 'n': case 'o': case 'p': case 'q': case 'r':
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case 's': case 't': case 'u': case 'v': case 'w': case 'x':
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case 'y': case 'z':
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case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
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case 'G': case 'H': case 'I': case 'J': case 'K': case 'L':
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case 'M': case 'N': case 'O': case 'P': case 'Q': case 'R':
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case 'S': case 'T': case 'U': case 'V': case 'W': case 'X':
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case 'Y': case 'Z':
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case '0': case '1': case '2': case '3': case '4': case '5':
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case '6': case '7': case '8': case '9':
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case ':':
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*out++ = *in++;
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break;
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default:
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/* unexpected character in symbol, not looks_like_rust. */
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goto fail;
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}
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goto done;
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fail:
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*out++ = '?'; /* This is pretty lame, but it's hard to do better. */
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done:
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*out = '\0';
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}
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static int
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unescape (const char **in, char **out, const char *seq, char value)
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{
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size_t len = strlen (seq);
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if (strncmp (*in, seq, len))
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return 0;
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**out = value;
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*in += len;
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*out += 1;
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return 1;
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}
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