llvm-project/llvm/lib/Demangle/RustDemangle.cpp

393 lines
9.8 KiB
C++

//===--- RustDemangle.cpp ---------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines a demangler for Rust v0 mangled symbols as specified in
// https://rust-lang.github.io/rfcs/2603-rust-symbol-name-mangling-v0.html
//
//===----------------------------------------------------------------------===//
#include "llvm/Demangle/RustDemangle.h"
#include "llvm/Demangle/Demangle.h"
#include <algorithm>
#include <cassert>
#include <cstring>
#include <limits>
using namespace llvm;
using namespace rust_demangle;
char *llvm::rustDemangle(const char *MangledName, char *Buf, size_t *N,
int *Status) {
if (MangledName == nullptr || (Buf != nullptr && N == nullptr)) {
if (Status != nullptr)
*Status = demangle_invalid_args;
return nullptr;
}
// Return early if mangled name doesn't look like a Rust symbol.
StringView Mangled(MangledName);
if (!Mangled.startsWith("_R")) {
if (Status != nullptr)
*Status = demangle_invalid_mangled_name;
return nullptr;
}
Demangler D;
if (!initializeOutputStream(nullptr, nullptr, D.Output, 1024)) {
if (Status != nullptr)
*Status = demangle_memory_alloc_failure;
return nullptr;
}
if (!D.demangle(Mangled)) {
if (Status != nullptr)
*Status = demangle_invalid_mangled_name;
std::free(D.Output.getBuffer());
return nullptr;
}
D.Output += '\0';
char *Demangled = D.Output.getBuffer();
size_t DemangledLen = D.Output.getCurrentPosition();
if (Buf != nullptr) {
if (DemangledLen <= *N) {
std::memcpy(Buf, Demangled, DemangledLen);
std::free(Demangled);
Demangled = Buf;
} else {
std::free(Buf);
}
}
if (N != nullptr)
*N = DemangledLen;
if (Status != nullptr)
*Status = demangle_success;
return Demangled;
}
Demangler::Demangler(size_t MaxRecursionLevel)
: MaxRecursionLevel(MaxRecursionLevel) {}
static inline bool isDigit(const char C) { return '0' <= C && C <= '9'; }
static inline bool isLower(const char C) { return 'a' <= C && C <= 'z'; }
static inline bool isUpper(const char C) { return 'A' <= C && C <= 'Z'; }
/// Returns true if C is a valid mangled character: <0-9a-zA-Z_>.
static inline bool isValid(const char C) {
return isDigit(C) || isLower(C) || isUpper(C) || C == '_';
}
// Demangles Rust v0 mangled symbol. Returns true when successful, and false
// otherwise. The demangled symbol is stored in Output field. It is
// responsibility of the caller to free the memory behind the output stream.
//
// <symbol-name> = "_R" <path> [<instantiating-crate>]
bool Demangler::demangle(StringView Mangled) {
Position = 0;
Error = false;
RecursionLevel = 0;
if (!Mangled.consumeFront("_R")) {
Error = true;
return false;
}
Input = Mangled;
demanglePath();
// FIXME parse optional <instantiating-crate>.
if (Position != Input.size())
Error = true;
return !Error;
}
// <path> = "C" <identifier> // crate root
// | "M" <impl-path> <type> // <T> (inherent impl)
// | "X" <impl-path> <type> <path> // <T as Trait> (trait impl)
// | "Y" <type> <path> // <T as Trait> (trait definition)
// | "N" <ns> <path> <identifier> // ...::ident (nested path)
// | "I" <path> {<generic-arg>} "E" // ...<T, U> (generic args)
// | <backref>
// <identifier> = [<disambiguator>] <undisambiguated-identifier>
// <ns> = "C" // closure
// | "S" // shim
// | <A-Z> // other special namespaces
// | <a-z> // internal namespaces
void Demangler::demanglePath() {
if (Error || RecursionLevel >= MaxRecursionLevel) {
Error = true;
return;
}
SwapAndRestore<size_t> SaveRecursionLevel(RecursionLevel, RecursionLevel + 1);
switch (consume()) {
case 'C': {
parseOptionalBase62Number('s');
Identifier Ident = parseIdentifier();
print(Ident.Name);
break;
}
case 'N': {
char NS = consume();
if (!isLower(NS) && !isUpper(NS)) {
Error = true;
break;
}
demanglePath();
uint64_t Disambiguator = parseOptionalBase62Number('s');
Identifier Ident = parseIdentifier();
if (isUpper(NS)) {
// Special namespaces
print("::{");
if (NS == 'C')
print("closure");
else if (NS == 'S')
print("shim");
else
print(NS);
if (!Ident.empty()) {
print(":");
print(Ident.Name);
}
print('#');
printDecimalNumber(Disambiguator);
print('}');
} else {
// Implementation internal namespaces.
if (!Ident.empty()) {
print("::");
print(Ident.Name);
}
}
break;
}
case 'I': {
demanglePath();
print("::<");
for (size_t I = 0; !Error && !consumeIf('E'); ++I) {
if (I > 0)
print(", ");
demangleGenericArg();
}
print(">");
break;
}
default:
// FIXME parse remaining productions.
Error = true;
break;
}
}
// <generic-arg> = <lifetime>
// | <type>
// | "K" <const>
// <lifetime> = "L" <base-62-number>
void Demangler::demangleGenericArg() {
// FIXME parse remaining productions
demangleType();
}
static const char *const BasicTypes[] = {
"i8", // a
"bool", // b
"char", // c
"f64", // d
"str", // e
"f32", // f
nullptr, // g
"u8", // h
"isize", // i
"usize", // j
nullptr, // k
"i32", // l
"u32", // m
"i128", // n
"u128", // o
"_", // p
nullptr, // q
nullptr, // r
"i16", // s
"u16", // t
"()", // u
"...", // v
nullptr, // w
"i64", // x
"u64", // y
"!", // z
};
// <basic-type> = "a" // i8
// | "b" // bool
// | "c" // char
// | "d" // f64
// | "e" // str
// | "f" // f32
// | "h" // u8
// | "i" // isize
// | "j" // usize
// | "l" // i32
// | "m" // u32
// | "n" // i128
// | "o" // u128
// | "s" // i16
// | "t" // u16
// | "u" // ()
// | "v" // ...
// | "x" // i64
// | "y" // u64
// | "z" // !
// | "p" // placeholder (e.g. for generic params), shown as _
static const char *parseBasicType(char C) {
if (isLower(C))
return BasicTypes[C - 'a'];
return nullptr;
}
// <type> = | <basic-type>
// | <path> // named type
// | "A" <type> <const> // [T; N]
// | "S" <type> // [T]
// | "T" {<type>} "E" // (T1, T2, T3, ...)
// | "R" [<lifetime>] <type> // &T
// | "Q" [<lifetime>] <type> // &mut T
// | "P" <type> // *const T
// | "O" <type> // *mut T
// | "F" <fn-sig> // fn(...) -> ...
// | "D" <dyn-bounds> <lifetime> // dyn Trait<Assoc = X> + Send + 'a
// | <backref> // backref
void Demangler::demangleType() {
if (const char *BasicType = parseBasicType(consume())) {
print(BasicType);
} else {
// FIXME parse remaining productions.
Error = true;
}
}
// <undisambiguated-identifier> = ["u"] <decimal-number> ["_"] <bytes>
Identifier Demangler::parseIdentifier() {
bool Punycode = consumeIf('u');
uint64_t Bytes = parseDecimalNumber();
// Underscore resolves the ambiguity when identifier starts with a decimal
// digit or another underscore.
consumeIf('_');
if (Error || Bytes > Input.size() - Position) {
Error = true;
return {};
}
StringView S = Input.substr(Position, Bytes);
Position += Bytes;
if (!std::all_of(S.begin(), S.end(), isValid)) {
Error = true;
return {};
}
return {S, Punycode};
}
// Parses optional base 62 number. The presence of a number is determined using
// Tag. Returns 0 when tag is absent and parsed value + 1 otherwise.
uint64_t Demangler::parseOptionalBase62Number(char Tag) {
if (!consumeIf(Tag))
return 0;
uint64_t N = parseBase62Number();
if (Error || !addAssign(N, 1))
return 0;
return N;
}
// Parses base 62 number with <0-9a-zA-Z> as digits. Number is terminated by
// "_". All values are offset by 1, so that "_" encodes 0, "0_" encodes 1,
// "1_" encodes 2, etc.
//
// <base-62-number> = {<0-9a-zA-Z>} "_"
uint64_t Demangler::parseBase62Number() {
if (consumeIf('_'))
return 0;
uint64_t Value = 0;
while (true) {
uint64_t Digit;
char C = consume();
if (C == '_') {
break;
} else if (isDigit(C)) {
Digit = C - '0';
} else if (isLower(C)) {
Digit = 10 + (C - 'a');
} else if (isUpper(C)) {
Digit = 10 + 26 + (C - 'A');
} else {
Error = true;
return 0;
}
if (!mulAssign(Value, 62))
return 0;
if (!addAssign(Value, Digit))
return 0;
}
if (!addAssign(Value, 1))
return 0;
return Value;
}
// Parses a decimal number that had been encoded without any leading zeros.
//
// <decimal-number> = "0"
// | <1-9> {<0-9>}
uint64_t Demangler::parseDecimalNumber() {
char C = look();
if (!isDigit(C)) {
Error = true;
return 0;
}
if (C == '0') {
consume();
return 0;
}
uint64_t Value = 0;
while (isDigit(look())) {
if (!mulAssign(Value, 10)) {
Error = true;
return 0;
}
uint64_t D = consume() - '0';
if (!addAssign(Value, D))
return 0;
}
return Value;
}