Fairphone ODM | 25c12f5 | 2023-12-15 17:24:06 +0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2018 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | |
| 18 | /* |
| 19 | * WARNING: Do not include and use these directly. Use jni_macros.h instead! |
| 20 | * The "detail" namespace should be a strong hint not to depend on the internals, |
| 21 | * which could change at any time. |
| 22 | * |
| 23 | * This implements the underlying mechanism for compile-time JNI signature/ctype checking |
| 24 | * and inference. |
| 25 | * |
| 26 | * This file provides the constexpr basic blocks such as strings, arrays, vectors |
| 27 | * as well as the JNI-specific parsing functionality. |
| 28 | * |
| 29 | * Everything is implemented via generic-style (templates without metaprogramming) |
| 30 | * wherever possible. Traditional template metaprogramming is used sparingly. |
| 31 | * |
| 32 | * Everything in this file except ostream<< is constexpr. |
| 33 | */ |
| 34 | |
| 35 | #pragma once |
| 36 | |
| 37 | #include <iostream> // std::ostream |
| 38 | #include <jni.h> // jni typedefs, JniNativeMethod. |
| 39 | #include <type_traits> // std::common_type, std::remove_cv |
| 40 | |
| 41 | namespace nativehelper { |
| 42 | namespace detail { |
| 43 | |
| 44 | // If CHECK evaluates to false then X_ASSERT will halt compilation. |
| 45 | // |
| 46 | // Asserts meant to be used only within constexpr context. |
| 47 | #if defined(JNI_SIGNATURE_CHECKER_DISABLE_ASSERTS) |
| 48 | # define X_ASSERT(CHECK) do { if ((false)) { (CHECK) ? void(0) : void(0); } } while (false) |
| 49 | #else |
| 50 | # define X_ASSERT(CHECK) \ |
| 51 | ( (CHECK) ? void(0) : jni_assertion_failure(#CHECK) ) |
| 52 | #endif |
| 53 | |
| 54 | // The runtime 'jni_assert' will never get called from a constexpr context; |
| 55 | // instead compilation will abort with a stack trace. |
| 56 | // |
| 57 | // Inspect the frame above this one to see the exact nature of the failure. |
| 58 | inline void jni_assertion_failure(const char* /*msg*/) __attribute__((noreturn)); |
| 59 | inline void jni_assertion_failure(const char* /*msg*/) { |
| 60 | std::terminate(); |
| 61 | } |
| 62 | |
| 63 | // An immutable constexpr string view, similar to std::string_view but for C++14. |
| 64 | // For a mutable string see instead ConstexprVector<char>. |
| 65 | // |
| 66 | // As it is a read-only view into a string, it is not guaranteed to be zero-terminated. |
| 67 | struct ConstexprStringView { |
| 68 | // Implicit conversion from string literal: |
| 69 | // ConstexprStringView str = "hello_world"; |
| 70 | template<size_t N> |
| 71 | constexpr ConstexprStringView(const char (& lit)[N]) // NOLINT: explicit. |
| 72 | : _array(lit), _size(N - 1) { |
| 73 | // Using an array of characters is not allowed because the inferred size would be wrong. |
| 74 | // Use the other constructor instead for that. |
| 75 | X_ASSERT(lit[N - 1] == '\0'); |
| 76 | } |
| 77 | |
| 78 | constexpr ConstexprStringView(const char* ptr, size_t size) |
| 79 | : _array(ptr), _size(size) { |
| 80 | // See the below constructor instead. |
| 81 | X_ASSERT(ptr != nullptr); |
| 82 | } |
| 83 | |
| 84 | // No-arg constructor: Create empty view. |
| 85 | constexpr ConstexprStringView() : _array(""), _size(0u) {} |
| 86 | |
| 87 | constexpr size_t size() const { |
| 88 | return _size; |
| 89 | } |
| 90 | |
| 91 | constexpr bool empty() const { |
| 92 | return size() == 0u; |
| 93 | } |
| 94 | |
| 95 | constexpr char operator[](size_t i) const { |
| 96 | X_ASSERT(i <= size()); |
| 97 | return _array[i]; |
| 98 | } |
| 99 | |
| 100 | // Create substring from this[start..start+len). |
| 101 | constexpr ConstexprStringView substr(size_t start, size_t len) const { |
| 102 | X_ASSERT(start <= size()); |
| 103 | X_ASSERT(len <= size() - start); |
| 104 | |
| 105 | return ConstexprStringView(&_array[start], len); |
| 106 | } |
| 107 | |
| 108 | // Create maximum length substring that begins at 'start'. |
| 109 | constexpr ConstexprStringView substr(size_t start) const { |
| 110 | X_ASSERT(start <= size()); |
| 111 | return substr(start, size() - start); |
| 112 | } |
| 113 | |
| 114 | using const_iterator = const char*; |
| 115 | |
| 116 | constexpr const_iterator begin() const { |
| 117 | return &_array[0]; |
| 118 | } |
| 119 | |
| 120 | constexpr const_iterator end() const { |
| 121 | return &_array[size()]; |
| 122 | } |
| 123 | |
| 124 | private: |
| 125 | const char* _array; // Never-null for simplicity. |
| 126 | size_t _size; |
| 127 | }; |
| 128 | |
| 129 | constexpr bool |
| 130 | operator==(const ConstexprStringView& lhs, const ConstexprStringView& rhs) { |
| 131 | if (lhs.size() != rhs.size()) { |
| 132 | return false; |
| 133 | } |
| 134 | for (size_t i = 0; i < lhs.size(); ++i) { |
| 135 | if (lhs[i] != rhs[i]) { |
| 136 | return false; |
| 137 | } |
| 138 | } |
| 139 | return true; |
| 140 | } |
| 141 | |
| 142 | constexpr bool |
| 143 | operator!=(const ConstexprStringView& lhs, const ConstexprStringView& rhs) { |
| 144 | return !(lhs == rhs); |
| 145 | } |
| 146 | |
| 147 | inline std::ostream& operator<<(std::ostream& os, const ConstexprStringView& str) { |
| 148 | for (char c : str) { |
| 149 | os << c; |
| 150 | } |
| 151 | return os; |
| 152 | } |
| 153 | |
| 154 | constexpr bool IsValidJniDescriptorStart(char shorty) { |
| 155 | constexpr char kValidJniStarts[] = |
| 156 | {'V', 'Z', 'B', 'C', 'S', 'I', 'J', 'F', 'D', 'L', '[', '(', ')'}; |
| 157 | |
| 158 | for (char c : kValidJniStarts) { |
| 159 | if (c == shorty) { |
| 160 | return true; |
| 161 | } |
| 162 | } |
| 163 | |
| 164 | return false; |
| 165 | } |
| 166 | |
| 167 | // A constexpr "vector" that supports storing a variable amount of Ts |
| 168 | // in an array-like interface. |
| 169 | // |
| 170 | // An up-front kMaxSize must be given since constexpr does not support |
| 171 | // dynamic allocations. |
| 172 | template<typename T, size_t kMaxSize> |
| 173 | struct ConstexprVector { |
| 174 | public: |
| 175 | constexpr explicit ConstexprVector() : _size(0u), _array{} { |
| 176 | } |
| 177 | |
| 178 | private: |
| 179 | // Custom iterator to support ptr-one-past-end into the union array without |
| 180 | // undefined behavior. |
| 181 | template<typename Elem> |
| 182 | struct VectorIterator { |
| 183 | Elem* ptr; |
| 184 | |
| 185 | constexpr VectorIterator& operator++() { |
| 186 | ++ptr; |
| 187 | return *this; |
| 188 | } |
| 189 | |
| 190 | constexpr VectorIterator operator++(int) const { |
| 191 | VectorIterator tmp(*this); |
| 192 | ++tmp; |
| 193 | return tmp; |
| 194 | } |
| 195 | |
| 196 | constexpr /*T&*/ auto& operator*() { |
| 197 | // Use 'auto' here since using 'T' is incorrect with const_iterator. |
| 198 | return ptr->_value; |
| 199 | } |
| 200 | |
| 201 | constexpr const /*T&*/ auto& operator*() const { |
| 202 | // Use 'auto' here for consistency with above. |
| 203 | return ptr->_value; |
| 204 | } |
| 205 | |
| 206 | constexpr bool operator==(const VectorIterator& other) const { |
| 207 | return ptr == other.ptr; |
| 208 | } |
| 209 | |
| 210 | constexpr bool operator!=(const VectorIterator& other) const { |
| 211 | return !(*this == other); |
| 212 | } |
| 213 | }; |
| 214 | |
| 215 | // Do not require that T is default-constructible by using a union. |
| 216 | struct MaybeElement { |
| 217 | union { |
| 218 | T _value; |
| 219 | }; |
| 220 | }; |
| 221 | |
| 222 | public: |
| 223 | using iterator = VectorIterator<MaybeElement>; |
| 224 | using const_iterator = VectorIterator<const MaybeElement>; |
| 225 | |
| 226 | constexpr iterator begin() { |
| 227 | return {&_array[0]}; |
| 228 | } |
| 229 | |
| 230 | constexpr iterator end() { |
| 231 | return {&_array[size()]}; |
| 232 | } |
| 233 | |
| 234 | constexpr const_iterator begin() const { |
| 235 | return {&_array[0]}; |
| 236 | } |
| 237 | |
| 238 | constexpr const_iterator end() const { |
| 239 | return {&_array[size()]}; |
| 240 | } |
| 241 | |
| 242 | constexpr void push_back(const T& value) { |
| 243 | X_ASSERT(_size + 1 <= kMaxSize); |
| 244 | |
| 245 | _array[_size]._value = value; |
| 246 | _size++; |
| 247 | } |
| 248 | |
| 249 | // A pop operation could also be added since constexpr T's |
| 250 | // have default destructors, it would just be _size--. |
| 251 | // We do not need a pop() here though. |
| 252 | |
| 253 | constexpr const T& operator[](size_t i) const { |
| 254 | return _array[i]._value; |
| 255 | } |
| 256 | |
| 257 | constexpr T& operator[](size_t i) { |
| 258 | return _array[i]._value; |
| 259 | } |
| 260 | |
| 261 | constexpr size_t size() const { |
| 262 | return _size; |
| 263 | } |
| 264 | private: |
| 265 | |
| 266 | size_t _size; |
| 267 | MaybeElement _array[kMaxSize]; |
| 268 | }; |
| 269 | |
| 270 | // Parsed and validated "long" form of a single JNI descriptor. |
| 271 | // e.g. one of "J", "Ljava/lang/Object;" etc. |
| 272 | struct JniDescriptorNode { |
| 273 | ConstexprStringView longy; |
| 274 | |
| 275 | constexpr JniDescriptorNode(ConstexprStringView longy) : longy(longy) { // NOLINT(google-explicit-constructor) |
| 276 | X_ASSERT(!longy.empty()); |
| 277 | } |
| 278 | constexpr JniDescriptorNode() : longy() {} |
| 279 | |
| 280 | constexpr char shorty() { |
| 281 | // Must be initialized with the non-default constructor. |
| 282 | X_ASSERT(!longy.empty()); |
| 283 | return longy[0]; |
| 284 | } |
| 285 | }; |
| 286 | |
| 287 | inline std::ostream& operator<<(std::ostream& os, const JniDescriptorNode& node) { |
| 288 | os << node.longy; |
| 289 | return os; |
| 290 | } |
| 291 | |
| 292 | // Equivalent of C++17 std::optional. |
| 293 | // |
| 294 | // An optional is essentially a type safe |
| 295 | // union { |
| 296 | // void Nothing, |
| 297 | // T Some; |
| 298 | // }; |
| 299 | // |
| 300 | template<typename T> |
| 301 | struct ConstexprOptional { |
| 302 | // Create a default optional with no value. |
| 303 | constexpr ConstexprOptional() : _has_value(false), _nothing() { |
| 304 | } |
| 305 | |
| 306 | // Create an optional with a value. |
| 307 | constexpr ConstexprOptional(const T& value) // NOLINT(google-explicit-constructor) |
| 308 | : _has_value(true), _value(value) { |
| 309 | } |
| 310 | |
| 311 | constexpr explicit operator bool() const { |
| 312 | return _has_value; |
| 313 | } |
| 314 | |
| 315 | constexpr bool has_value() const { |
| 316 | return _has_value; |
| 317 | } |
| 318 | |
| 319 | constexpr const T& value() const { |
| 320 | X_ASSERT(has_value()); |
| 321 | return _value; |
| 322 | } |
| 323 | |
| 324 | constexpr const T* operator->() const { |
| 325 | return &(value()); |
| 326 | } |
| 327 | |
| 328 | constexpr const T& operator*() const { |
| 329 | return value(); |
| 330 | } |
| 331 | |
| 332 | private: |
| 333 | bool _has_value; |
| 334 | // The "Nothing" is likely unnecessary but improves readability. |
| 335 | struct Nothing {}; |
| 336 | union { |
| 337 | Nothing _nothing; |
| 338 | T _value; |
| 339 | }; |
| 340 | }; |
| 341 | |
| 342 | template<typename T> |
| 343 | constexpr bool |
| 344 | operator==(const ConstexprOptional<T>& lhs, const ConstexprOptional<T>& rhs) { |
| 345 | if (lhs && rhs) { |
| 346 | return lhs.value() == rhs.value(); |
| 347 | } |
| 348 | return lhs.has_value() == rhs.has_value(); |
| 349 | } |
| 350 | |
| 351 | template<typename T> |
| 352 | constexpr bool |
| 353 | operator!=(const ConstexprOptional<T>& lhs, const ConstexprOptional<T>& rhs) { |
| 354 | return !(lhs == rhs); |
| 355 | } |
| 356 | |
| 357 | template<typename T> |
| 358 | inline std::ostream& operator<<(std::ostream& os, const ConstexprOptional<T>& val) { |
| 359 | if (val) { |
| 360 | os << val.value(); |
| 361 | } |
| 362 | return os; |
| 363 | } |
| 364 | |
| 365 | // Equivalent of std::nullopt |
| 366 | // Allows implicit conversion to any empty ConstexprOptional<T>. |
| 367 | // Mostly useful for macros that need to return an empty constexpr optional. |
| 368 | struct NullConstexprOptional { |
| 369 | template<typename T> |
| 370 | constexpr operator ConstexprOptional<T>() const { // NOLINT(google-explicit-constructor) |
| 371 | return ConstexprOptional<T>(); |
| 372 | } |
| 373 | }; |
| 374 | |
| 375 | inline std::ostream& operator<<(std::ostream& os, NullConstexprOptional) { |
| 376 | return os; |
| 377 | } |
| 378 | |
| 379 | #if !defined(PARSE_FAILURES_NONFATAL) |
| 380 | // Unfortunately we cannot have custom messages here, as it just prints a stack trace with the |
| 381 | // macros expanded. This is at least more flexible than static_assert which requires a string |
| 382 | // literal. |
| 383 | // NOTE: The message string literal must be on same line as the macro to be seen during a |
| 384 | // compilation error. |
| 385 | #define PARSE_FAILURE(msg) X_ASSERT(! #msg) |
| 386 | #define PARSE_ASSERT_MSG(cond, msg) X_ASSERT(#msg && (cond)) |
| 387 | #define PARSE_ASSERT(cond) X_ASSERT(cond) |
| 388 | #else |
| 389 | #define PARSE_FAILURE(msg) return NullConstexprOptional{}; |
| 390 | #define PARSE_ASSERT_MSG(cond, msg) if (!(cond)) { PARSE_FAILURE(msg); } |
| 391 | #define PARSE_ASSERT(cond) if (!(cond)) { PARSE_FAILURE(""); } |
| 392 | #endif |
| 393 | |
| 394 | // This is a placeholder function and should not be called directly. |
| 395 | constexpr void ParseFailure(const char* msg) { |
| 396 | (void) msg; // intentionally no-op. |
| 397 | } |
| 398 | |
| 399 | // Temporary parse data when parsing a function descriptor. |
| 400 | struct ParseTypeDescriptorResult { |
| 401 | // A single argument descriptor, e.g. "V" or "Ljava/lang/Object;" |
| 402 | ConstexprStringView token; |
| 403 | // The remainder of the function descriptor yet to be parsed. |
| 404 | ConstexprStringView remainder; |
| 405 | |
| 406 | constexpr bool has_token() const { |
| 407 | return token.size() > 0u; |
| 408 | } |
| 409 | |
| 410 | constexpr bool has_remainder() const { |
| 411 | return remainder.size() > 0u; |
| 412 | } |
| 413 | |
| 414 | constexpr JniDescriptorNode as_node() const { |
| 415 | X_ASSERT(has_token()); |
| 416 | return {token}; |
| 417 | } |
| 418 | }; |
| 419 | |
| 420 | // Parse a single type descriptor out of a function type descriptor substring, |
| 421 | // and return the token and the remainder string. |
| 422 | // |
| 423 | // If parsing fails (i.e. illegal syntax), then: |
| 424 | // parses are fatal -> assertion is triggered (default behavior), |
| 425 | // parses are nonfatal -> returns nullopt (test behavior). |
| 426 | constexpr ConstexprOptional<ParseTypeDescriptorResult> |
| 427 | ParseSingleTypeDescriptor(ConstexprStringView single_type, |
| 428 | bool allow_void = false) { |
| 429 | constexpr NullConstexprOptional kUnreachable = {}; |
| 430 | |
| 431 | // Nothing else left. |
| 432 | if (single_type.size() == 0) { |
| 433 | return ParseTypeDescriptorResult{}; |
| 434 | } |
| 435 | |
| 436 | ConstexprStringView token; |
| 437 | ConstexprStringView remainder = single_type.substr(/*start*/1u); |
| 438 | |
| 439 | char c = single_type[0]; |
| 440 | PARSE_ASSERT(IsValidJniDescriptorStart(c)); |
| 441 | |
| 442 | enum State { |
| 443 | kSingleCharacter, |
| 444 | kArray, |
| 445 | kObject |
| 446 | }; |
| 447 | |
| 448 | State state = kSingleCharacter; |
| 449 | |
| 450 | // Parse the first character to figure out if we should parse the rest. |
| 451 | switch (c) { |
| 452 | case '!': { |
| 453 | constexpr bool fast_jni_is_deprecated = false; |
| 454 | PARSE_ASSERT(fast_jni_is_deprecated); |
| 455 | break; |
| 456 | } |
| 457 | case 'V': |
| 458 | if (!allow_void) { |
| 459 | constexpr bool void_type_descriptor_only_allowed_in_return_type = false; |
| 460 | PARSE_ASSERT(void_type_descriptor_only_allowed_in_return_type); |
| 461 | } |
| 462 | [[clang::fallthrough]]; |
| 463 | case 'Z': |
| 464 | case 'B': |
| 465 | case 'C': |
| 466 | case 'S': |
| 467 | case 'I': |
| 468 | case 'J': |
| 469 | case 'F': |
| 470 | case 'D': |
| 471 | token = single_type.substr(/*start*/0u, /*len*/1u); |
| 472 | break; |
| 473 | case 'L': |
| 474 | state = kObject; |
| 475 | break; |
| 476 | case '[': |
| 477 | state = kArray; |
| 478 | break; |
| 479 | default: { |
| 480 | // See JNI Chapter 3: Type Signatures. |
| 481 | PARSE_FAILURE("Expected a valid type descriptor character."); |
| 482 | return kUnreachable; |
| 483 | } |
| 484 | } |
| 485 | |
| 486 | // Possibly parse an arbitary-long remainder substring. |
| 487 | switch (state) { |
| 488 | case kSingleCharacter: |
| 489 | return {{token, remainder}}; |
| 490 | case kArray: { |
| 491 | // Recursively parse the array component, as it's just any non-void type descriptor. |
| 492 | ConstexprOptional<ParseTypeDescriptorResult> |
| 493 | maybe_res = ParseSingleTypeDescriptor(remainder, /*allow_void*/false); |
| 494 | PARSE_ASSERT(maybe_res); // Downstream parsing has asserted, bail out. |
| 495 | |
| 496 | ParseTypeDescriptorResult res = maybe_res.value(); |
| 497 | |
| 498 | // Reject illegal array type descriptors such as "]". |
| 499 | PARSE_ASSERT_MSG(res.has_token(), "All array types must follow by their component type (e.g. ']I', ']]Z', etc. "); |
| 500 | |
| 501 | token = single_type.substr(/*start*/0u, res.token.size() + 1u); |
| 502 | |
| 503 | return {{token, res.remainder}}; |
| 504 | } |
| 505 | case kObject: { |
| 506 | // Parse the fully qualified class, e.g. Lfoo/bar/baz; |
| 507 | // Note checking that each part of the class name is a valid class identifier |
| 508 | // is too complicated (JLS 3.8). |
| 509 | // This simple check simply scans until the next ';'. |
| 510 | bool found_semicolon = false; |
| 511 | size_t semicolon_len = 0; |
| 512 | for (size_t i = 0; i < single_type.size(); ++i) { |
| 513 | switch (single_type[i]) { |
| 514 | case ')': |
| 515 | case '(': |
| 516 | case '[': |
| 517 | PARSE_FAILURE("Object identifiers cannot have ()[ in them."); |
| 518 | break; |
| 519 | } |
| 520 | if (single_type[i] == ';') { |
| 521 | semicolon_len = i + 1; |
| 522 | found_semicolon = true; |
| 523 | break; |
| 524 | } |
| 525 | } |
| 526 | |
| 527 | PARSE_ASSERT(found_semicolon); |
| 528 | |
| 529 | token = single_type.substr(/*start*/0u, semicolon_len); |
| 530 | remainder = single_type.substr(/*start*/semicolon_len); |
| 531 | |
| 532 | bool class_name_is_empty = token.size() <= 2u; // e.g. "L;" |
| 533 | PARSE_ASSERT(!class_name_is_empty); |
| 534 | |
| 535 | return {{token, remainder}}; |
| 536 | } |
| 537 | default: |
| 538 | X_ASSERT(false); |
| 539 | } |
| 540 | |
| 541 | X_ASSERT(false); |
| 542 | return kUnreachable; |
| 543 | } |
| 544 | |
| 545 | // Abstract data type to represent container for Ret(Args,...). |
| 546 | template<typename T, size_t kMaxSize> |
| 547 | struct FunctionSignatureDescriptor { |
| 548 | ConstexprVector<T, kMaxSize> args; |
| 549 | T ret; |
| 550 | |
| 551 | static constexpr size_t max_size = kMaxSize; |
| 552 | }; |
| 553 | |
| 554 | |
| 555 | template<typename T, size_t kMaxSize> |
| 556 | inline std::ostream& operator<<( |
| 557 | std::ostream& os, |
| 558 | const FunctionSignatureDescriptor<T, kMaxSize>& signature) { |
| 559 | size_t count = 0; |
| 560 | os << "args={"; |
| 561 | for (auto& arg : signature.args) { |
| 562 | os << arg; |
| 563 | |
| 564 | if (count != signature.args.size() - 1) { |
| 565 | os << ","; |
| 566 | } |
| 567 | |
| 568 | ++count; |
| 569 | } |
| 570 | os << "}, ret="; |
| 571 | os << signature.ret; |
| 572 | return os; |
| 573 | } |
| 574 | |
| 575 | // Ret(Args...) of JniDescriptorNode. |
| 576 | template<size_t kMaxSize> |
| 577 | using JniSignatureDescriptor = FunctionSignatureDescriptor<JniDescriptorNode, |
| 578 | kMaxSize>; |
| 579 | |
| 580 | // Parse a JNI function signature descriptor into a JniSignatureDescriptor. |
| 581 | // |
| 582 | // If parsing fails (i.e. illegal syntax), then: |
| 583 | // parses are fatal -> assertion is triggered (default behavior), |
| 584 | // parses are nonfatal -> returns nullopt (test behavior). |
| 585 | template<size_t kMaxSize> |
| 586 | constexpr ConstexprOptional<JniSignatureDescriptor<kMaxSize>> |
| 587 | ParseSignatureAsList(ConstexprStringView signature) { |
| 588 | // The list of JNI descriptors cannot possibly exceed the number of characters |
| 589 | // in the JNI string literal. We leverage this to give an upper bound of the strlen. |
| 590 | // This is a bit wasteful but in constexpr there *must* be a fixed upper size for data structures. |
| 591 | ConstexprVector<JniDescriptorNode, kMaxSize> jni_desc_node_list; |
| 592 | JniDescriptorNode return_jni_desc; |
| 593 | |
| 594 | enum State { |
| 595 | kInitial = 0, |
| 596 | kParsingParameters = 1, |
| 597 | kParsingReturnType = 2, |
| 598 | kCompleted = 3, |
| 599 | }; |
| 600 | |
| 601 | State state = kInitial; |
| 602 | |
| 603 | while (!signature.empty()) { |
| 604 | switch (state) { |
| 605 | case kInitial: { |
| 606 | char c = signature[0]; |
| 607 | PARSE_ASSERT_MSG(c == '(', |
| 608 | "First character of a JNI signature must be a '('"); |
| 609 | state = kParsingParameters; |
| 610 | signature = signature.substr(/*start*/1u); |
| 611 | break; |
| 612 | } |
| 613 | case kParsingParameters: { |
| 614 | char c = signature[0]; |
| 615 | if (c == ')') { |
| 616 | state = kParsingReturnType; |
| 617 | signature = signature.substr(/*start*/1u); |
| 618 | break; |
| 619 | } |
| 620 | |
| 621 | ConstexprOptional<ParseTypeDescriptorResult> |
| 622 | res = ParseSingleTypeDescriptor(signature, /*allow_void*/false); |
| 623 | PARSE_ASSERT(res); |
| 624 | |
| 625 | jni_desc_node_list.push_back(res->as_node()); |
| 626 | |
| 627 | signature = res->remainder; |
| 628 | break; |
| 629 | } |
| 630 | case kParsingReturnType: { |
| 631 | ConstexprOptional<ParseTypeDescriptorResult> |
| 632 | res = ParseSingleTypeDescriptor(signature, /*allow_void*/true); |
| 633 | PARSE_ASSERT(res); |
| 634 | |
| 635 | return_jni_desc = res->as_node(); |
| 636 | signature = res->remainder; |
| 637 | state = kCompleted; |
| 638 | break; |
| 639 | } |
| 640 | default: { |
| 641 | // e.g. "()VI" is illegal because the V terminates the signature. |
| 642 | PARSE_FAILURE("Signature had left over tokens after parsing return type"); |
| 643 | break; |
| 644 | } |
| 645 | } |
| 646 | } |
| 647 | |
| 648 | switch (state) { |
| 649 | case kCompleted: |
| 650 | // Everything is ok. |
| 651 | break; |
| 652 | case kParsingParameters: |
| 653 | PARSE_FAILURE("Signature was missing ')'"); |
| 654 | break; |
| 655 | case kParsingReturnType: |
| 656 | PARSE_FAILURE("Missing return type"); |
| 657 | case kInitial: |
| 658 | PARSE_FAILURE("Cannot have an empty signature"); |
| 659 | default: |
| 660 | X_ASSERT(false); |
| 661 | } |
| 662 | |
| 663 | return {{jni_desc_node_list, return_jni_desc}}; |
| 664 | } |
| 665 | |
| 666 | // What kind of JNI does this type belong to? |
| 667 | enum NativeKind { |
| 668 | kNotJni, // Illegal parameter used inside of a function type. |
| 669 | kNormalJniCallingConventionParameter, |
| 670 | kNormalNative, |
| 671 | kFastNative, // Also valid in normal. |
| 672 | kCriticalNative, // Also valid in fast/normal. |
| 673 | }; |
| 674 | |
| 675 | // Is this type final, i.e. it cannot be subtyped? |
| 676 | enum TypeFinal { |
| 677 | kNotFinal, |
| 678 | kFinal // e.g. any primitive or any "final" class such as String. |
| 679 | }; |
| 680 | |
| 681 | // What position is the JNI type allowed to be in? |
| 682 | // Ignored when in a CriticalNative context. |
| 683 | enum NativePositionAllowed { |
| 684 | kNotAnyPosition, |
| 685 | kReturnPosition, |
| 686 | kZerothPosition, |
| 687 | kFirstOrLaterPosition, |
| 688 | kSecondOrLaterPosition, |
| 689 | }; |
| 690 | |
| 691 | constexpr NativePositionAllowed ConvertPositionToAllowed(size_t position) { |
| 692 | switch (position) { |
| 693 | case 0: |
| 694 | return kZerothPosition; |
| 695 | case 1: |
| 696 | return kFirstOrLaterPosition; |
| 697 | default: |
| 698 | return kSecondOrLaterPosition; |
| 699 | } |
| 700 | } |
| 701 | |
| 702 | // Type traits for a JNI parameter type. See below for specializations. |
| 703 | template<typename T> |
| 704 | struct jni_type_trait { |
| 705 | static constexpr NativeKind native_kind = kNotJni; |
| 706 | static constexpr const char type_descriptor[] = "(illegal)"; |
| 707 | static constexpr NativePositionAllowed position_allowed = kNotAnyPosition; |
| 708 | static constexpr TypeFinal type_finality = kNotFinal; |
| 709 | static constexpr const char type_name[] = "(illegal)"; |
| 710 | }; |
| 711 | |
| 712 | // Access the jni_type_trait<T> from a non-templated constexpr function. |
| 713 | // Identical non-static fields to jni_type_trait, see Reify(). |
| 714 | struct ReifiedJniTypeTrait { |
| 715 | NativeKind native_kind; |
| 716 | ConstexprStringView type_descriptor; |
| 717 | NativePositionAllowed position_allowed; |
| 718 | TypeFinal type_finality; |
| 719 | ConstexprStringView type_name; |
| 720 | |
| 721 | template<typename T> |
| 722 | static constexpr ReifiedJniTypeTrait Reify() { |
| 723 | // This should perhaps be called 'Type Erasure' except we don't use virtuals, |
| 724 | // so it's not quite the same idiom. |
| 725 | using TR = jni_type_trait<T>; |
| 726 | return {TR::native_kind, |
| 727 | TR::type_descriptor, |
| 728 | TR::position_allowed, |
| 729 | TR::type_finality, |
| 730 | TR::type_name}; |
| 731 | } |
| 732 | |
| 733 | // Find the most similar ReifiedJniTypeTrait corresponding to the type descriptor. |
| 734 | // |
| 735 | // Any type can be found by using the exact canonical type descriptor as listed |
| 736 | // in the jni type traits definitions. |
| 737 | // |
| 738 | // Non-final JNI types have limited support for inexact similarity: |
| 739 | // [[* | [L* -> jobjectArray |
| 740 | // L* -> jobject |
| 741 | // |
| 742 | // Otherwise return a nullopt. |
| 743 | static constexpr ConstexprOptional<ReifiedJniTypeTrait> |
| 744 | MostSimilarTypeDescriptor(ConstexprStringView type_descriptor); |
| 745 | }; |
| 746 | |
| 747 | constexpr bool |
| 748 | operator==(const ReifiedJniTypeTrait& lhs, const ReifiedJniTypeTrait& rhs) { |
| 749 | return lhs.native_kind == rhs.native_kind |
| 750 | && rhs.type_descriptor == lhs.type_descriptor && |
| 751 | lhs.position_allowed == rhs.position_allowed |
| 752 | && rhs.type_finality == lhs.type_finality && |
| 753 | lhs.type_name == rhs.type_name; |
| 754 | } |
| 755 | |
| 756 | inline std::ostream& operator<<(std::ostream& os, const ReifiedJniTypeTrait& rjtt) { |
| 757 | // os << "ReifiedJniTypeTrait<" << rjft.type_name << ">"; |
| 758 | os << rjtt.type_name; |
| 759 | return os; |
| 760 | } |
| 761 | |
| 762 | // Template specialization for any JNI typedefs. |
| 763 | #define JNI_TYPE_TRAIT(jtype, the_type_descriptor, the_native_kind, the_type_finality, the_position) \ |
| 764 | template <> \ |
| 765 | struct jni_type_trait< jtype > { \ |
| 766 | static constexpr NativeKind native_kind = the_native_kind; \ |
| 767 | static constexpr const char type_descriptor[] = the_type_descriptor; \ |
| 768 | static constexpr NativePositionAllowed position_allowed = the_position; \ |
| 769 | static constexpr TypeFinal type_finality = the_type_finality; \ |
| 770 | static constexpr const char type_name[] = #jtype; \ |
| 771 | }; |
| 772 | |
| 773 | #define DEFINE_JNI_TYPE_TRAIT(TYPE_TRAIT_FN) \ |
| 774 | TYPE_TRAIT_FN(jboolean, "Z", kCriticalNative, kFinal, kSecondOrLaterPosition) \ |
| 775 | TYPE_TRAIT_FN(jbyte, "B", kCriticalNative, kFinal, kSecondOrLaterPosition) \ |
| 776 | TYPE_TRAIT_FN(jchar, "C", kCriticalNative, kFinal, kSecondOrLaterPosition) \ |
| 777 | TYPE_TRAIT_FN(jshort, "S", kCriticalNative, kFinal, kSecondOrLaterPosition) \ |
| 778 | TYPE_TRAIT_FN(jint, "I", kCriticalNative, kFinal, kSecondOrLaterPosition) \ |
| 779 | TYPE_TRAIT_FN(jlong, "J", kCriticalNative, kFinal, kSecondOrLaterPosition) \ |
| 780 | TYPE_TRAIT_FN(jfloat, "F", kCriticalNative, kFinal, kSecondOrLaterPosition) \ |
| 781 | TYPE_TRAIT_FN(jdouble, "D", kCriticalNative, kFinal, kSecondOrLaterPosition) \ |
| 782 | TYPE_TRAIT_FN(jobject, "Ljava/lang/Object;", kFastNative, kNotFinal, kFirstOrLaterPosition) \ |
| 783 | TYPE_TRAIT_FN(jclass, "Ljava/lang/Class;", kFastNative, kFinal, kFirstOrLaterPosition) \ |
| 784 | TYPE_TRAIT_FN(jstring, "Ljava/lang/String;", kFastNative, kFinal, kSecondOrLaterPosition) \ |
| 785 | TYPE_TRAIT_FN(jarray, "Ljava/lang/Object;", kFastNative, kNotFinal, kSecondOrLaterPosition) \ |
| 786 | TYPE_TRAIT_FN(jobjectArray, "[Ljava/lang/Object;", kFastNative, kNotFinal, kSecondOrLaterPosition) \ |
| 787 | TYPE_TRAIT_FN(jbooleanArray, "[Z", kFastNative, kFinal, kSecondOrLaterPosition) \ |
| 788 | TYPE_TRAIT_FN(jbyteArray, "[B", kFastNative, kFinal, kSecondOrLaterPosition) \ |
| 789 | TYPE_TRAIT_FN(jcharArray, "[C", kFastNative, kFinal, kSecondOrLaterPosition) \ |
| 790 | TYPE_TRAIT_FN(jshortArray, "[S", kFastNative, kFinal, kSecondOrLaterPosition) \ |
| 791 | TYPE_TRAIT_FN(jintArray, "[I", kFastNative, kFinal, kSecondOrLaterPosition) \ |
| 792 | TYPE_TRAIT_FN(jlongArray, "[J", kFastNative, kFinal, kSecondOrLaterPosition) \ |
| 793 | TYPE_TRAIT_FN(jfloatArray, "[F", kFastNative, kFinal, kSecondOrLaterPosition) \ |
| 794 | TYPE_TRAIT_FN(jdoubleArray, "[D", kFastNative, kFinal, kSecondOrLaterPosition) \ |
| 795 | TYPE_TRAIT_FN(jthrowable, "Ljava/lang/Throwable;", kFastNative, kNotFinal, kSecondOrLaterPosition) \ |
| 796 | TYPE_TRAIT_FN(JNIEnv*, "", kNormalJniCallingConventionParameter, kFinal, kZerothPosition) \ |
| 797 | TYPE_TRAIT_FN(void, "V", kCriticalNative, kFinal, kReturnPosition) \ |
| 798 | |
| 799 | DEFINE_JNI_TYPE_TRAIT(JNI_TYPE_TRAIT) |
| 800 | |
| 801 | // See ReifiedJniTypeTrait for documentation. |
| 802 | constexpr ConstexprOptional<ReifiedJniTypeTrait> |
| 803 | ReifiedJniTypeTrait::MostSimilarTypeDescriptor(ConstexprStringView type_descriptor) { |
| 804 | #define MATCH_EXACT_TYPE_DESCRIPTOR_FN(type, type_desc, native_kind, ...) \ |
| 805 | if (type_descriptor == type_desc && native_kind >= kNormalNative) { \ |
| 806 | return { Reify<type>() }; \ |
| 807 | } |
| 808 | |
| 809 | // Attempt to look up by the precise type match first. |
| 810 | DEFINE_JNI_TYPE_TRAIT(MATCH_EXACT_TYPE_DESCRIPTOR_FN); |
| 811 | |
| 812 | // Otherwise, we need to do an imprecise match: |
| 813 | char shorty = type_descriptor.size() >= 1 ? type_descriptor[0] : '\0'; |
| 814 | if (shorty == 'L') { |
| 815 | // Something more specific like Ljava/lang/Throwable, string, etc |
| 816 | // is already matched by the macro-expanded conditions above. |
| 817 | return {Reify<jobject>()}; |
| 818 | } else if (type_descriptor.size() >= 2) { |
| 819 | auto shorty_shorty = type_descriptor.substr(/*start*/0, /*size*/2u); |
| 820 | if (shorty_shorty == "[[" || shorty_shorty == "[L") { |
| 821 | // JNI arrays are covariant, so any type T[] (T!=primitive) is castable to Object[]. |
| 822 | return {Reify<jobjectArray>()}; |
| 823 | } |
| 824 | } |
| 825 | |
| 826 | // To handle completely invalid values. |
| 827 | return NullConstexprOptional{}; |
| 828 | } |
| 829 | |
| 830 | // Is this actual JNI position consistent with the expected position? |
| 831 | constexpr bool IsValidJniParameterPosition(NativeKind native_kind, |
| 832 | NativePositionAllowed position, |
| 833 | NativePositionAllowed expected_position) { |
| 834 | X_ASSERT(expected_position != kNotAnyPosition); |
| 835 | |
| 836 | if (native_kind == kCriticalNative) { |
| 837 | // CriticalNatives ignore positions since the first 2 special |
| 838 | // parameters are stripped. |
| 839 | return true; |
| 840 | } |
| 841 | |
| 842 | // Is this a return-only position? |
| 843 | if (expected_position == kReturnPosition) { |
| 844 | if (position != kReturnPosition) { |
| 845 | // void can only be in the return position. |
| 846 | return false; |
| 847 | } |
| 848 | // Don't do the other non-return position checks for a return-only position. |
| 849 | return true; |
| 850 | } |
| 851 | |
| 852 | // JNIEnv* can only be in the first spot. |
| 853 | if (position == kZerothPosition && expected_position != kZerothPosition) { |
| 854 | return false; |
| 855 | // jobject, jclass can be 1st or anywhere afterwards. |
| 856 | } else if (position == kFirstOrLaterPosition && expected_position != kFirstOrLaterPosition) { |
| 857 | return false; |
| 858 | // All other parameters must be in 2nd+ spot, or in the return type. |
| 859 | } else if (position == kSecondOrLaterPosition || position == kReturnPosition) { |
| 860 | if (expected_position != kFirstOrLaterPosition && expected_position != kSecondOrLaterPosition) { |
| 861 | return false; |
| 862 | } |
| 863 | } |
| 864 | |
| 865 | return true; |
| 866 | } |
| 867 | |
| 868 | // Check if a jni parameter type is valid given its position and native_kind. |
| 869 | template <typename T> |
| 870 | constexpr bool IsValidJniParameter(NativeKind native_kind, NativePositionAllowed position) { |
| 871 | // const,volatile does not affect JNI compatibility since it does not change ABI. |
| 872 | using expected_trait = jni_type_trait<typename std::remove_cv<T>::type>; |
| 873 | NativeKind expected_native_kind = expected_trait::native_kind; |
| 874 | |
| 875 | // Most types 'T' are not valid for JNI. |
| 876 | if (expected_native_kind == NativeKind::kNotJni) { |
| 877 | return false; |
| 878 | } |
| 879 | |
| 880 | // The rest of the types might be valid, but it depends on the context (native_kind) |
| 881 | // and also on their position within the parameters. |
| 882 | |
| 883 | // Position-check first. |
| 884 | NativePositionAllowed expected_position = expected_trait::position_allowed; |
| 885 | if (!IsValidJniParameterPosition(native_kind, position, expected_position)) { |
| 886 | return false; |
| 887 | } |
| 888 | |
| 889 | // Ensure the type appropriate is for the native kind. |
| 890 | if (expected_native_kind == kNormalJniCallingConventionParameter) { |
| 891 | // It's always wrong to use a JNIEnv* anywhere but the 0th spot. |
| 892 | if (native_kind == kCriticalNative) { |
| 893 | // CriticalNative does not allow using a JNIEnv*. |
| 894 | return false; |
| 895 | } |
| 896 | |
| 897 | return true; // OK: JniEnv* used in 0th position. |
| 898 | } else if (expected_native_kind == kCriticalNative) { |
| 899 | // CriticalNative arguments are always valid JNI types anywhere used. |
| 900 | return true; |
| 901 | } else if (native_kind == kCriticalNative) { |
| 902 | // The expected_native_kind was non-critical but we are in a critical context. |
| 903 | // Illegal type. |
| 904 | return false; |
| 905 | } |
| 906 | |
| 907 | // Everything else is fine, e.g. fast/normal native + fast/normal native parameters. |
| 908 | return true; |
| 909 | } |
| 910 | |
| 911 | // Is there sufficient number of parameters given the kind of JNI that it is? |
| 912 | constexpr bool IsJniParameterCountValid(NativeKind native_kind, size_t count) { |
| 913 | if (native_kind == kNormalNative || native_kind == kFastNative) { |
| 914 | return count >= 2u; |
| 915 | } else if (native_kind == kCriticalNative) { |
| 916 | return true; |
| 917 | } |
| 918 | |
| 919 | constexpr bool invalid_parameter = false; |
| 920 | X_ASSERT(invalid_parameter); |
| 921 | return false; |
| 922 | } |
| 923 | |
| 924 | // Basic template interface. See below for partial specializations. |
| 925 | // |
| 926 | // Each instantiation will have a 'value' field that determines whether or not |
| 927 | // all of the Args are valid JNI arguments given their native_kind. |
| 928 | template<NativeKind native_kind, size_t position, typename ... Args> |
| 929 | struct is_valid_jni_argument_type { |
| 930 | // static constexpr bool value = ?; |
| 931 | }; |
| 932 | |
| 933 | template<NativeKind native_kind, size_t position> |
| 934 | struct is_valid_jni_argument_type<native_kind, position> { |
| 935 | static constexpr bool value = true; |
| 936 | }; |
| 937 | |
| 938 | template<NativeKind native_kind, size_t position, typename T> |
| 939 | struct is_valid_jni_argument_type<native_kind, position, T> { |
| 940 | static constexpr bool value = |
| 941 | IsValidJniParameter<T>(native_kind, ConvertPositionToAllowed(position)); |
| 942 | }; |
| 943 | |
| 944 | template<NativeKind native_kind, size_t position, typename T, typename ... Args> |
| 945 | struct is_valid_jni_argument_type<native_kind, position, T, Args...> { |
| 946 | static constexpr bool value = |
| 947 | IsValidJniParameter<T>(native_kind, ConvertPositionToAllowed(position)) |
| 948 | && is_valid_jni_argument_type<native_kind, |
| 949 | position + 1, |
| 950 | Args...>::value; |
| 951 | }; |
| 952 | |
| 953 | // This helper is required to decompose the function type into a list of arg types. |
| 954 | template<NativeKind native_kind, typename T, T* fn> |
| 955 | struct is_valid_jni_function_type_helper; |
| 956 | |
| 957 | template<NativeKind native_kind, typename R, typename ... Args, R (*fn)(Args...)> |
| 958 | struct is_valid_jni_function_type_helper<native_kind, R(Args...), fn> { |
| 959 | static constexpr bool value = |
| 960 | IsJniParameterCountValid(native_kind, sizeof...(Args)) |
| 961 | && IsValidJniParameter<R>(native_kind, kReturnPosition) |
| 962 | && is_valid_jni_argument_type<native_kind, /*position*/ |
| 963 | 0, |
| 964 | Args...>::value; |
| 965 | }; |
| 966 | |
| 967 | // Is this function type 'T' a valid C++ function type given the native_kind? |
| 968 | template<NativeKind native_kind, typename T, T* fn> |
| 969 | constexpr bool IsValidJniFunctionType() { |
| 970 | return is_valid_jni_function_type_helper<native_kind, T, fn>::value; |
| 971 | // TODO: we could replace template metaprogramming with constexpr by |
| 972 | // using FunctionTypeMetafunction. |
| 973 | } |
| 974 | |
| 975 | // Many parts of std::array is not constexpr until C++17. |
| 976 | template<typename T, size_t N> |
| 977 | struct ConstexprArray { |
| 978 | // Intentionally public to conform to std::array. |
| 979 | // This means all constructors are implicit. |
| 980 | // *NOT* meant to be used directly, use the below functions instead. |
| 981 | // |
| 982 | // The reason std::array has it is to support direct-list-initialization, |
| 983 | // e.g. "ConstexprArray<T, sz>{T{...}, T{...}, T{...}, ...};" |
| 984 | // |
| 985 | // Note that otherwise this would need a very complicated variadic |
| 986 | // argument constructor to only support list of Ts. |
| 987 | T _array[N]; |
| 988 | |
| 989 | constexpr size_t size() const { |
| 990 | return N; |
| 991 | } |
| 992 | |
| 993 | using iterator = T*; |
| 994 | using const_iterator = const T*; |
| 995 | |
| 996 | constexpr iterator begin() { |
| 997 | return &_array[0]; |
| 998 | } |
| 999 | |
| 1000 | constexpr iterator end() { |
| 1001 | return &_array[N]; |
| 1002 | } |
| 1003 | |
| 1004 | constexpr const_iterator begin() const { |
| 1005 | return &_array[0]; |
| 1006 | } |
| 1007 | |
| 1008 | constexpr const_iterator end() const { |
| 1009 | return &_array[N]; |
| 1010 | } |
| 1011 | |
| 1012 | constexpr T& operator[](size_t i) { |
| 1013 | return _array[i]; |
| 1014 | } |
| 1015 | |
| 1016 | constexpr const T& operator[](size_t i) const { |
| 1017 | return _array[i]; |
| 1018 | } |
| 1019 | }; |
| 1020 | |
| 1021 | // Why do we need this? |
| 1022 | // auto x = {1,2,3} creates an initializer_list, |
| 1023 | // but they can't be returned because it contains pointers to temporaries. |
| 1024 | // auto x[] = {1,2,3} doesn't even work because auto for arrays is not supported. |
| 1025 | // |
| 1026 | // an alternative would be to pull up std::common_t directly into the call site |
| 1027 | // std::common_type_t<Args...> array[] = {1,2,3} |
| 1028 | // but that's even more cludgier. |
| 1029 | // |
| 1030 | // As the other "stdlib-wannabe" functions, it's weaker than the library |
| 1031 | // fundamentals std::make_array but good enough for our use. |
| 1032 | template<typename... Args> |
| 1033 | constexpr auto MakeArray(Args&& ... args) { |
| 1034 | return ConstexprArray<typename std::common_type<Args...>::type, |
| 1035 | sizeof...(Args)>{args...}; |
| 1036 | } |
| 1037 | |
| 1038 | // See below. |
| 1039 | template<typename T, T* fn> |
| 1040 | struct FunctionTypeMetafunction { |
| 1041 | }; |
| 1042 | |
| 1043 | // Enables the "map" operation over the function component types. |
| 1044 | template<typename R, typename ... Args, R (*fn)(Args...)> |
| 1045 | struct FunctionTypeMetafunction<R(Args...), fn> { |
| 1046 | // Count how many arguments there are, and add 1 for the return type. |
| 1047 | static constexpr size_t |
| 1048 | count = sizeof...(Args) + 1u; // args and return type. |
| 1049 | |
| 1050 | // Return an array where the metafunction 'Func' has been applied |
| 1051 | // to every argument type. The metafunction must be returning a common type. |
| 1052 | template<template<typename Arg> class Func> |
| 1053 | static constexpr auto map_args() { |
| 1054 | return map_args_impl<Func>(holder < Args > {}...); |
| 1055 | } |
| 1056 | |
| 1057 | // Apply the metafunction 'Func' over the return type. |
| 1058 | template<template<typename Ret> class Func> |
| 1059 | static constexpr auto map_return() { |
| 1060 | return Func<R>{}(); |
| 1061 | } |
| 1062 | |
| 1063 | private: |
| 1064 | template<typename T> |
| 1065 | struct holder { |
| 1066 | }; |
| 1067 | |
| 1068 | template<template<typename Arg> class Func, typename Arg0, typename... ArgsRest> |
| 1069 | static constexpr auto map_args_impl(holder<Arg0>, holder<ArgsRest>...) { |
| 1070 | // One does not simply call MakeArray with 0 template arguments... |
| 1071 | auto array = MakeArray( |
| 1072 | Func<Args>{}()... |
| 1073 | ); |
| 1074 | |
| 1075 | return array; |
| 1076 | } |
| 1077 | |
| 1078 | template<template<typename Arg> class Func> |
| 1079 | static constexpr auto map_args_impl() { |
| 1080 | // This overload provides support for MakeArray() with 0 arguments. |
| 1081 | using ComponentType = decltype(Func<void>{}()); |
| 1082 | |
| 1083 | return ConstexprArray<ComponentType, /*size*/0u>{}; |
| 1084 | } |
| 1085 | }; |
| 1086 | |
| 1087 | // Apply ReifiedJniTypeTrait::Reify<T> for every function component type. |
| 1088 | template<typename T> |
| 1089 | struct ReifyJniTypeMetafunction { |
| 1090 | constexpr ReifiedJniTypeTrait operator()() const { |
| 1091 | auto res = ReifiedJniTypeTrait::Reify<T>(); |
| 1092 | X_ASSERT(res.native_kind != kNotJni); |
| 1093 | return res; |
| 1094 | } |
| 1095 | }; |
| 1096 | |
| 1097 | // Ret(Args...) where every component is a ReifiedJniTypeTrait. |
| 1098 | template<size_t kMaxSize> |
| 1099 | using ReifiedJniSignature = FunctionSignatureDescriptor<ReifiedJniTypeTrait, |
| 1100 | kMaxSize>; |
| 1101 | |
| 1102 | // Attempts to convert the function type T into a list of ReifiedJniTypeTraits |
| 1103 | // that correspond to the function components. |
| 1104 | // |
| 1105 | // If conversion fails (i.e. non-jni compatible types), then: |
| 1106 | // parses are fatal -> assertion is triggered (default behavior), |
| 1107 | // parses are nonfatal -> returns nullopt (test behavior). |
| 1108 | template <NativeKind native_kind, |
| 1109 | typename T, |
| 1110 | T* fn, |
| 1111 | size_t kMaxSize = FunctionTypeMetafunction<T, fn>::count> |
| 1112 | constexpr ConstexprOptional<ReifiedJniSignature<kMaxSize>> |
| 1113 | MaybeMakeReifiedJniSignature() { |
| 1114 | if (!IsValidJniFunctionType<native_kind, T, fn>()) { |
| 1115 | PARSE_FAILURE("The function signature has one or more types incompatible with JNI."); |
| 1116 | } |
| 1117 | |
| 1118 | ReifiedJniTypeTrait return_jni_trait = |
| 1119 | FunctionTypeMetafunction<T, |
| 1120 | fn>::template map_return<ReifyJniTypeMetafunction>(); |
| 1121 | |
| 1122 | constexpr size_t |
| 1123 | kSkipArgumentPrefix = (native_kind != kCriticalNative) ? 2u : 0u; |
| 1124 | ConstexprVector<ReifiedJniTypeTrait, kMaxSize> args; |
| 1125 | auto args_list = |
| 1126 | FunctionTypeMetafunction<T, fn>::template map_args<ReifyJniTypeMetafunction>(); |
| 1127 | size_t args_index = 0; |
| 1128 | for (auto& arg : args_list) { |
| 1129 | // Ignore the 'JNIEnv*, jobject' / 'JNIEnv*, jclass' prefix, |
| 1130 | // as its not part of the function descriptor string. |
| 1131 | if (args_index >= kSkipArgumentPrefix) { |
| 1132 | args.push_back(arg); |
| 1133 | } |
| 1134 | |
| 1135 | ++args_index; |
| 1136 | } |
| 1137 | |
| 1138 | return {{args, return_jni_trait}}; |
| 1139 | } |
| 1140 | |
| 1141 | #define COMPARE_DESCRIPTOR_CHECK(expr) if (!(expr)) return false |
| 1142 | #define COMPARE_DESCRIPTOR_FAILURE_MSG(msg) if ((true)) return false |
| 1143 | |
| 1144 | // Compares a user-defined JNI descriptor (of a single argument or return value) |
| 1145 | // to a reified jni type trait that was derived from the C++ function type. |
| 1146 | // |
| 1147 | // If comparison fails (i.e. non-jni compatible types), then: |
| 1148 | // parses are fatal -> assertion is triggered (default behavior), |
| 1149 | // parses are nonfatal -> returns false (test behavior). |
| 1150 | constexpr bool |
| 1151 | CompareJniDescriptorNodeErased(JniDescriptorNode user_defined_descriptor, |
| 1152 | ReifiedJniTypeTrait derived) { |
| 1153 | |
| 1154 | ConstexprOptional<ReifiedJniTypeTrait> user_reified_opt = |
| 1155 | ReifiedJniTypeTrait::MostSimilarTypeDescriptor(user_defined_descriptor.longy); |
| 1156 | |
| 1157 | if (!user_reified_opt.has_value()) { |
| 1158 | COMPARE_DESCRIPTOR_FAILURE_MSG( |
| 1159 | "Could not find any JNI C++ type corresponding to the type descriptor"); |
| 1160 | } |
| 1161 | |
| 1162 | char user_shorty = user_defined_descriptor.longy.size() > 0 ? |
| 1163 | user_defined_descriptor.longy[0] : |
| 1164 | '\0'; |
| 1165 | |
| 1166 | ReifiedJniTypeTrait user = user_reified_opt.value(); |
| 1167 | if (user == derived) { |
| 1168 | // If we had a similar match, immediately return success. |
| 1169 | return true; |
| 1170 | } else if (derived.type_name == "jthrowable") { |
| 1171 | if (user_shorty == 'L') { |
| 1172 | // Weakly allow any objects to correspond to a jthrowable. |
| 1173 | // We do not know the managed type system so we have to be permissive here. |
| 1174 | return true; |
| 1175 | } else { |
| 1176 | COMPARE_DESCRIPTOR_FAILURE_MSG( |
| 1177 | "jthrowable must correspond to an object type descriptor"); |
| 1178 | } |
| 1179 | } else if (derived.type_name == "jarray") { |
| 1180 | if (user_shorty == '[') { |
| 1181 | // a jarray is the base type for all other array types. Allow. |
| 1182 | return true; |
| 1183 | } else { |
| 1184 | // Ljava/lang/Object; is the root for all array types. |
| 1185 | // Already handled above in 'if user == derived'. |
| 1186 | COMPARE_DESCRIPTOR_FAILURE_MSG( |
| 1187 | "jarray must correspond to array type descriptor"); |
| 1188 | } |
| 1189 | } |
| 1190 | // Otherwise, the comparison has failed and the rest of this is only to |
| 1191 | // pick the most appropriate error message. |
| 1192 | // |
| 1193 | // Note: A weaker form of comparison would allow matching 'Ljava/lang/String;' |
| 1194 | // against 'jobject', etc. However the policy choice here is to enforce the strictest |
| 1195 | // comparison that we can to utilize the type system to its fullest. |
| 1196 | |
| 1197 | if (derived.type_finality == kFinal || user.type_finality == kFinal) { |
| 1198 | // Final types, e.g. "I", "Ljava/lang/String;" etc must match exactly |
| 1199 | // the C++ jni descriptor string ('I' -> jint, 'Ljava/lang/String;' -> jstring). |
| 1200 | COMPARE_DESCRIPTOR_FAILURE_MSG( |
| 1201 | "The JNI descriptor string must be the exact type equivalent of the " |
| 1202 | "C++ function signature."); |
| 1203 | } else if (user_shorty == '[') { |
| 1204 | COMPARE_DESCRIPTOR_FAILURE_MSG( |
| 1205 | "The array JNI descriptor must correspond to j${type}Array or jarray"); |
| 1206 | } else if (user_shorty == 'L') { |
| 1207 | COMPARE_DESCRIPTOR_FAILURE_MSG( |
| 1208 | "The object JNI descriptor must correspond to jobject."); |
| 1209 | } else { |
| 1210 | X_ASSERT(false); // We should never get here, but either way this means the types did not match |
| 1211 | COMPARE_DESCRIPTOR_FAILURE_MSG( |
| 1212 | "The JNI type descriptor string does not correspond to the C++ JNI type."); |
| 1213 | } |
| 1214 | } |
| 1215 | |
| 1216 | // Matches a user-defined JNI function descriptor against the C++ function type. |
| 1217 | // |
| 1218 | // If matches fails, then: |
| 1219 | // parses are fatal -> assertion is triggered (default behavior), |
| 1220 | // parses are nonfatal -> returns false (test behavior). |
| 1221 | template<NativeKind native_kind, typename T, T* fn, size_t kMaxSize> |
| 1222 | constexpr bool |
| 1223 | MatchJniDescriptorWithFunctionType(ConstexprStringView user_function_descriptor) { |
| 1224 | constexpr size_t kReifiedMaxSize = FunctionTypeMetafunction<T, fn>::count; |
| 1225 | |
| 1226 | ConstexprOptional<ReifiedJniSignature<kReifiedMaxSize>> |
| 1227 | reified_signature_opt = |
| 1228 | MaybeMakeReifiedJniSignature<native_kind, T, fn>(); |
| 1229 | if (!reified_signature_opt) { |
| 1230 | // Assertion handling done by MaybeMakeReifiedJniSignature. |
| 1231 | return false; |
| 1232 | } |
| 1233 | |
| 1234 | ConstexprOptional<JniSignatureDescriptor<kMaxSize>> user_jni_sig_desc_opt = |
| 1235 | ParseSignatureAsList<kMaxSize>(user_function_descriptor); |
| 1236 | |
| 1237 | if (!user_jni_sig_desc_opt) { |
| 1238 | // Assertion handling done by ParseSignatureAsList. |
| 1239 | return false; |
| 1240 | } |
| 1241 | |
| 1242 | ReifiedJniSignature<kReifiedMaxSize> |
| 1243 | reified_signature = reified_signature_opt.value(); |
| 1244 | JniSignatureDescriptor<kMaxSize> |
| 1245 | user_jni_sig_desc = user_jni_sig_desc_opt.value(); |
| 1246 | |
| 1247 | if (reified_signature.args.size() != user_jni_sig_desc.args.size()) { |
| 1248 | COMPARE_DESCRIPTOR_FAILURE_MSG( |
| 1249 | "Number of parameters in JNI descriptor string" |
| 1250 | "did not match number of parameters in C++ function type"); |
| 1251 | } else if (!CompareJniDescriptorNodeErased(user_jni_sig_desc.ret, |
| 1252 | reified_signature.ret)) { |
| 1253 | // Assertion handling done by CompareJniDescriptorNodeErased. |
| 1254 | return false; |
| 1255 | } else { |
| 1256 | for (size_t i = 0; i < user_jni_sig_desc.args.size(); ++i) { |
| 1257 | if (!CompareJniDescriptorNodeErased(user_jni_sig_desc.args[i], |
| 1258 | reified_signature.args[i])) { |
| 1259 | // Assertion handling done by CompareJniDescriptorNodeErased. |
| 1260 | return false; |
| 1261 | } |
| 1262 | } |
| 1263 | } |
| 1264 | |
| 1265 | return true; |
| 1266 | } |
| 1267 | |
| 1268 | // Supports inferring the JNI function descriptor string from the C++ |
| 1269 | // function type when all type components are final. |
| 1270 | template<NativeKind native_kind, typename T, T* fn> |
| 1271 | struct InferJniDescriptor { |
| 1272 | static constexpr size_t kMaxSize = FunctionTypeMetafunction<T, fn>::count; |
| 1273 | |
| 1274 | // Convert the C++ function type into a JniSignatureDescriptor which holds |
| 1275 | // the canonical (according to jni_traits) descriptors for each component. |
| 1276 | // The C++ type -> JNI mapping must be nonambiguous (see jni_macros.h for exact rules). |
| 1277 | // |
| 1278 | // If conversion fails (i.e. C++ signatures is illegal for JNI, or the types are ambiguous): |
| 1279 | // if parsing is fatal -> assertion failure (default behavior) |
| 1280 | // if parsing is nonfatal -> returns nullopt (test behavior). |
| 1281 | static constexpr ConstexprOptional<JniSignatureDescriptor<kMaxSize>> FromFunctionType() { |
| 1282 | constexpr size_t kReifiedMaxSize = kMaxSize; |
| 1283 | ConstexprOptional<ReifiedJniSignature<kReifiedMaxSize>> |
| 1284 | reified_signature_opt = |
| 1285 | MaybeMakeReifiedJniSignature<native_kind, T, fn>(); |
| 1286 | if (!reified_signature_opt) { |
| 1287 | // Assertion handling done by MaybeMakeReifiedJniSignature. |
| 1288 | return NullConstexprOptional{}; |
| 1289 | } |
| 1290 | |
| 1291 | ReifiedJniSignature<kReifiedMaxSize> |
| 1292 | reified_signature = reified_signature_opt.value(); |
| 1293 | |
| 1294 | JniSignatureDescriptor<kReifiedMaxSize> signature_descriptor; |
| 1295 | |
| 1296 | if (reified_signature.ret.type_finality != kFinal) { |
| 1297 | // e.g. jint, jfloatArray, jstring, jclass are ok. jobject, jthrowable, jarray are not. |
| 1298 | PARSE_FAILURE("Bad return type. Only unambigous (final) types can be used to infer a signature."); // NOLINT |
| 1299 | } |
| 1300 | signature_descriptor.ret = |
| 1301 | JniDescriptorNode{reified_signature.ret.type_descriptor}; |
| 1302 | |
| 1303 | for (size_t i = 0; i < reified_signature.args.size(); ++i) { |
| 1304 | const ReifiedJniTypeTrait& arg_trait = reified_signature.args[i]; |
| 1305 | if (arg_trait.type_finality != kFinal) { |
| 1306 | PARSE_FAILURE("Bad parameter type. Only unambigous (final) types can be used to infer a signature."); // NOLINT |
| 1307 | } |
| 1308 | signature_descriptor.args.push_back(JniDescriptorNode{ |
| 1309 | arg_trait.type_descriptor}); |
| 1310 | } |
| 1311 | |
| 1312 | return {signature_descriptor}; |
| 1313 | } |
| 1314 | |
| 1315 | // Calculate the exact string size that the JNI descriptor will be |
| 1316 | // at runtime. |
| 1317 | // |
| 1318 | // Without this we cannot allocate enough space within static storage |
| 1319 | // to fit the compile-time evaluated string. |
| 1320 | static constexpr size_t CalculateStringSize() { |
| 1321 | ConstexprOptional<JniSignatureDescriptor<kMaxSize>> |
| 1322 | signature_descriptor_opt = |
| 1323 | FromFunctionType(); |
| 1324 | if (!signature_descriptor_opt) { |
| 1325 | // Assertion handling done by FromFunctionType. |
| 1326 | return 0u; |
| 1327 | } |
| 1328 | |
| 1329 | JniSignatureDescriptor<kMaxSize> signature_descriptor = |
| 1330 | signature_descriptor_opt.value(); |
| 1331 | |
| 1332 | size_t acc_size = 1u; // All sigs start with '('. |
| 1333 | |
| 1334 | // Now add every parameter. |
| 1335 | for (size_t j = 0; j < signature_descriptor.args.size(); ++j) { |
| 1336 | const JniDescriptorNode& arg_descriptor = signature_descriptor.args[j]; |
| 1337 | // for (const JniDescriptorNode& arg_descriptor : signature_descriptor.args) { |
| 1338 | acc_size += arg_descriptor.longy.size(); |
| 1339 | } |
| 1340 | |
| 1341 | acc_size += 1u; // Add space for ')'. |
| 1342 | |
| 1343 | // Add space for the return value. |
| 1344 | acc_size += signature_descriptor.ret.longy.size(); |
| 1345 | |
| 1346 | return acc_size; |
| 1347 | } |
| 1348 | |
| 1349 | static constexpr size_t kMaxStringSize = CalculateStringSize(); |
| 1350 | using ConstexprStringDescriptorType = ConstexprArray<char, |
| 1351 | kMaxStringSize + 1>; |
| 1352 | |
| 1353 | // Convert the JniSignatureDescriptor we get in FromFunctionType() |
| 1354 | // into a flat constexpr char array. |
| 1355 | // |
| 1356 | // This is done by repeated string concatenation at compile-time. |
| 1357 | static constexpr ConstexprStringDescriptorType GetString() { |
| 1358 | ConstexprStringDescriptorType c_str{}; |
| 1359 | |
| 1360 | ConstexprOptional<JniSignatureDescriptor<kMaxSize>> |
| 1361 | signature_descriptor_opt = |
| 1362 | FromFunctionType(); |
| 1363 | if (!signature_descriptor_opt.has_value()) { |
| 1364 | // Assertion handling done by FromFunctionType. |
| 1365 | c_str[0] = '\0'; |
| 1366 | return c_str; |
| 1367 | } |
| 1368 | |
| 1369 | JniSignatureDescriptor<kMaxSize> signature_descriptor = |
| 1370 | signature_descriptor_opt.value(); |
| 1371 | |
| 1372 | size_t pos = 0u; |
| 1373 | c_str[pos++] = '('; |
| 1374 | |
| 1375 | // Copy all parameter descriptors. |
| 1376 | for (size_t j = 0; j < signature_descriptor.args.size(); ++j) { |
| 1377 | const JniDescriptorNode& arg_descriptor = signature_descriptor.args[j]; |
| 1378 | ConstexprStringView longy = arg_descriptor.longy; |
| 1379 | for (size_t i = 0; i < longy.size(); ++i) { |
| 1380 | c_str[pos++] = longy[i]; |
| 1381 | } |
| 1382 | } |
| 1383 | |
| 1384 | c_str[pos++] = ')'; |
| 1385 | |
| 1386 | // Copy return descriptor. |
| 1387 | ConstexprStringView longy = signature_descriptor.ret.longy; |
| 1388 | for (size_t i = 0; i < longy.size(); ++i) { |
| 1389 | c_str[pos++] = longy[i]; |
| 1390 | } |
| 1391 | |
| 1392 | X_ASSERT(pos == kMaxStringSize); |
| 1393 | |
| 1394 | c_str[pos] = '\0'; |
| 1395 | |
| 1396 | return c_str; |
| 1397 | } |
| 1398 | |
| 1399 | // Turn a pure constexpr string into one that can be accessed at non-constexpr |
| 1400 | // time. Note that the 'static constexpr' storage must be in the scope of a |
| 1401 | // function (prior to C++17) to avoid linking errors. |
| 1402 | static const char* GetStringAtRuntime() { |
| 1403 | static constexpr ConstexprStringDescriptorType str = GetString(); |
| 1404 | return &str[0]; |
| 1405 | } |
| 1406 | }; |
| 1407 | |
| 1408 | // Expression to return JNINativeMethod, performs checking on signature+fn. |
| 1409 | #define MAKE_CHECKED_JNI_NATIVE_METHOD(native_kind, name_, signature_, fn) \ |
| 1410 | ([]() { \ |
| 1411 | using namespace nativehelper::detail; /* NOLINT(google-build-using-namespace) */ \ |
| 1412 | static_assert( \ |
| 1413 | MatchJniDescriptorWithFunctionType<native_kind, \ |
| 1414 | decltype(fn), \ |
| 1415 | fn, \ |
| 1416 | sizeof(signature_)>(signature_),\ |
| 1417 | "JNI signature doesn't match C++ function type."); \ |
| 1418 | /* Suppress implicit cast warnings by explicitly casting. */ \ |
| 1419 | return JNINativeMethod { \ |
| 1420 | const_cast<decltype(JNINativeMethod::name)>(name_), \ |
| 1421 | const_cast<decltype(JNINativeMethod::signature)>(signature_), \ |
| 1422 | reinterpret_cast<void*>(&(fn))}; \ |
| 1423 | })() |
| 1424 | |
| 1425 | // Expression to return JNINativeMethod, infers signature from fn. |
| 1426 | #define MAKE_INFERRED_JNI_NATIVE_METHOD(native_kind, name_, fn) \ |
| 1427 | ([]() { \ |
| 1428 | using namespace nativehelper::detail; /* NOLINT(google-build-using-namespace) */ \ |
| 1429 | /* Suppress implicit cast warnings by explicitly casting. */ \ |
| 1430 | return JNINativeMethod { \ |
| 1431 | const_cast<decltype(JNINativeMethod::name)>(name_), \ |
| 1432 | const_cast<decltype(JNINativeMethod::signature)>( \ |
| 1433 | InferJniDescriptor<native_kind, \ |
| 1434 | decltype(fn), \ |
| 1435 | fn>::GetStringAtRuntime()), \ |
| 1436 | reinterpret_cast<void*>(&(fn))}; \ |
| 1437 | })() |
| 1438 | |
| 1439 | } // namespace detail |
| 1440 | } // namespace nativehelper |
| 1441 | |