+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0
-#include <string.h>
-#include "debug.h"
-
-#include "demangle-rust.h"
-
-/*
- * Mangled Rust symbols look like this:
- *
- * _$LT$std..sys..fd..FileDesc$u20$as$u20$core..ops..Drop$GT$::drop::hc68340e1baa4987a
- *
- * The original symbol is:
- *
- * <std::sys::fd::FileDesc as core::ops::Drop>::drop
- *
- * The last component of the path is a 64-bit hash in lowercase hex, prefixed
- * with "h". Rust does not have a global namespace between crates, an illusion
- * which Rust maintains by using the hash to distinguish things that would
- * otherwise have the same symbol.
- *
- * Any path component not starting with a XID_Start character is prefixed with
- * "_".
- *
- * The following escape sequences are used:
- *
- * "," => $C$
- * "@" => $SP$
- * "*" => $BP$
- * "&" => $RF$
- * "<" => $LT$
- * ">" => $GT$
- * "(" => $LP$
- * ")" => $RP$
- * " " => $u20$
- * "'" => $u27$
- * "[" => $u5b$
- * "]" => $u5d$
- * "~" => $u7e$
- *
- * A double ".." means "::" and a single "." means "-".
- *
- * The only characters allowed in the mangled symbol are a-zA-Z0-9 and _.:$
- */
-
-static const char *hash_prefix = "::h";
-static const size_t hash_prefix_len = 3;
-static const size_t hash_len = 16;
-
-static bool is_prefixed_hash(const char *start);
-static bool looks_like_rust(const char *sym, size_t len);
-static bool unescape(const char **in, char **out, const char *seq, char value);
-
-/*
- * INPUT:
- * sym: symbol that has been through BFD-demangling
- *
- * This function looks for the following indicators:
- *
- * 1. The hash must consist of "h" followed by 16 lowercase hex digits.
- *
- * 2. As a sanity check, the hash must use between 5 and 15 of the 16 possible
- * hex digits. This is true of 99.9998% of hashes so once in your life you
- * may see a false negative. The point is to notice path components that
- * could be Rust hashes but are probably not, like "haaaaaaaaaaaaaaaa". In
- * this case a false positive (non-Rust symbol has an important path
- * component removed because it looks like a Rust hash) is worse than a
- * false negative (the rare Rust symbol is not demangled) so this sets the
- * balance in favor of false negatives.
- *
- * 3. There must be no characters other than a-zA-Z0-9 and _.:$
- *
- * 4. There must be no unrecognized $-sign sequences.
- *
- * 5. There must be no sequence of three or more dots in a row ("...").
- */
-bool
-rust_is_mangled(const char *sym)
-{
- size_t len, len_without_hash;
-
- if (!sym)
- return false;
-
- len = strlen(sym);
- if (len <= hash_prefix_len + hash_len)
- /* Not long enough to contain "::h" + hash + something else */
- return false;
-
- len_without_hash = len - (hash_prefix_len + hash_len);
- if (!is_prefixed_hash(sym + len_without_hash))
- return false;
-
- return looks_like_rust(sym, len_without_hash);
-}
-
-/*
- * A hash is the prefix "::h" followed by 16 lowercase hex digits. The hex
- * digits must comprise between 5 and 15 (inclusive) distinct digits.
- */
-static bool is_prefixed_hash(const char *str)
-{
- const char *end;
- bool seen[16];
- size_t i;
- int count;
-
- if (strncmp(str, hash_prefix, hash_prefix_len))
- return false;
- str += hash_prefix_len;
-
- memset(seen, false, sizeof(seen));
- for (end = str + hash_len; str < end; str++)
- if (*str >= '0' && *str <= '9')
- seen[*str - '0'] = true;
- else if (*str >= 'a' && *str <= 'f')
- seen[*str - 'a' + 10] = true;
- else
- return false;
-
- /* Count how many distinct digits seen */
- count = 0;
- for (i = 0; i < 16; i++)
- if (seen[i])
- count++;
-
- return count >= 5 && count <= 15;
-}
-
-static bool looks_like_rust(const char *str, size_t len)
-{
- const char *end = str + len;
-
- while (str < end)
- switch (*str) {
- case '$':
- if (!strncmp(str, "$C$", 3))
- str += 3;
- else if (!strncmp(str, "$SP$", 4)
- || !strncmp(str, "$BP$", 4)
- || !strncmp(str, "$RF$", 4)
- || !strncmp(str, "$LT$", 4)
- || !strncmp(str, "$GT$", 4)
- || !strncmp(str, "$LP$", 4)
- || !strncmp(str, "$RP$", 4))
- str += 4;
- else if (!strncmp(str, "$u20$", 5)
- || !strncmp(str, "$u27$", 5)
- || !strncmp(str, "$u5b$", 5)
- || !strncmp(str, "$u5d$", 5)
- || !strncmp(str, "$u7e$", 5))
- str += 5;
- else
- return false;
- break;
- case '.':
- /* Do not allow three or more consecutive dots */
- if (!strncmp(str, "...", 3))
- return false;
- /* Fall through */
- case 'a' ... 'z':
- case 'A' ... 'Z':
- case '0' ... '9':
- case '_':
- case ':':
- str++;
- break;
- default:
- return false;
- }
-
- return true;
-}
-
-/*
- * INPUT:
- * sym: symbol for which rust_is_mangled(sym) returns true
- *
- * The input is demangled in-place because the mangled name is always longer
- * than the demangled one.
- */
-void
-rust_demangle_sym(char *sym)
-{
- const char *in;
- char *out;
- const char *end;
-
- if (!sym)
- return;
-
- in = sym;
- out = sym;
- end = sym + strlen(sym) - (hash_prefix_len + hash_len);
-
- while (in < end)
- switch (*in) {
- case '$':
- if (!(unescape(&in, &out, "$C$", ',')
- || unescape(&in, &out, "$SP$", '@')
- || unescape(&in, &out, "$BP$", '*')
- || unescape(&in, &out, "$RF$", '&')
- || unescape(&in, &out, "$LT$", '<')
- || unescape(&in, &out, "$GT$", '>')
- || unescape(&in, &out, "$LP$", '(')
- || unescape(&in, &out, "$RP$", ')')
- || unescape(&in, &out, "$u20$", ' ')
- || unescape(&in, &out, "$u27$", '\'')
- || unescape(&in, &out, "$u5b$", '[')
- || unescape(&in, &out, "$u5d$", ']')
- || unescape(&in, &out, "$u7e$", '~'))) {
- pr_err("demangle-rust: unexpected escape sequence");
- goto done;
- }
- break;
- case '_':
- /*
- * If this is the start of a path component and the next
- * character is an escape sequence, ignore the
- * underscore. The mangler inserts an underscore to make
- * sure the path component begins with a XID_Start
- * character.
- */
- if ((in == sym || in[-1] == ':') && in[1] == '$')
- in++;
- else
- *out++ = *in++;
- break;
- case '.':
- if (in[1] == '.') {
- /* ".." becomes "::" */
- *out++ = ':';
- *out++ = ':';
- in += 2;
- } else {
- /* "." becomes "-" */
- *out++ = '-';
- in++;
- }
- break;
- case 'a' ... 'z':
- case 'A' ... 'Z':
- case '0' ... '9':
- case ':':
- *out++ = *in++;
- break;
- default:
- pr_err("demangle-rust: unexpected character '%c' in symbol\n",
- *in);
- goto done;
- }
-
-done:
- *out = '\0';
-}
-
-static bool unescape(const char **in, char **out, const char *seq, char value)
-{
- size_t len = strlen(seq);
-
- if (strncmp(*in, seq, len))
- return false;
-
- **out = value;
-
- *in += len;
- *out += 1;
-
- return true;
-}
projects / linux-block.git / commitdiff