BacktraceOffline.cpp revision 02092b36da261c1a411dcf76c00b188e78e21b68
1/* 2 * Copyright (C) 2015 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#include "BacktraceOffline.h" 18 19extern "C" { 20#define UNW_REMOTE_ONLY 21#include <dwarf.h> 22} 23 24#include <stdint.h> 25#include <stdio.h> 26#include <string.h> 27#include <sys/stat.h> 28#include <sys/types.h> 29#include <ucontext.h> 30#include <unistd.h> 31 32#include <memory> 33#include <string> 34#include <vector> 35 36#include <android-base/file.h> 37#include <backtrace/Backtrace.h> 38#include <backtrace/BacktraceMap.h> 39#include <ziparchive/zip_archive.h> 40 41#pragma clang diagnostic push 42#pragma clang diagnostic ignored "-Wunused-parameter" 43 44#include <llvm/ADT/StringRef.h> 45#include <llvm/Object/Binary.h> 46#include <llvm/Object/ELFObjectFile.h> 47#include <llvm/Object/ObjectFile.h> 48 49#pragma clang diagnostic pop 50 51#include "BacktraceLog.h" 52 53void Space::Clear() { 54 start = 0; 55 end = 0; 56 data = nullptr; 57} 58 59size_t Space::Read(uint64_t addr, uint8_t* buffer, size_t size) { 60 if (addr >= start && addr < end) { 61 size_t read_size = std::min(size, static_cast<size_t>(end - addr)); 62 memcpy(buffer, data + (addr - start), read_size); 63 return read_size; 64 } 65 return 0; 66} 67 68static int FindProcInfo(unw_addr_space_t addr_space, unw_word_t ip, unw_proc_info* proc_info, 69 int need_unwind_info, void* arg) { 70 BacktraceOffline* backtrace = reinterpret_cast<BacktraceOffline*>(arg); 71 bool result = backtrace->FindProcInfo(addr_space, ip, proc_info, need_unwind_info); 72 return result ? 0 : -UNW_EINVAL; 73} 74 75static void PutUnwindInfo(unw_addr_space_t, unw_proc_info_t*, void*) { 76} 77 78static int GetDynInfoListAddr(unw_addr_space_t, unw_word_t*, void*) { 79 return -UNW_ENOINFO; 80} 81 82static int AccessMem(unw_addr_space_t, unw_word_t addr, unw_word_t* value, int write, void* arg) { 83 if (write == 1) { 84 return -UNW_EINVAL; 85 } 86 BacktraceOffline* backtrace = reinterpret_cast<BacktraceOffline*>(arg); 87 *value = 0; 88 size_t read_size = backtrace->Read(addr, reinterpret_cast<uint8_t*>(value), sizeof(unw_word_t)); 89 // Strictly we should check if read_size matches sizeof(unw_word_t), but it is possible in 90 // .eh_frame_hdr that the section can end at a position not aligned in sizeof(unw_word_t), and 91 // we should permit the read at the end of the section. 92 return (read_size > 0u ? 0 : -UNW_EINVAL); 93} 94 95static int AccessReg(unw_addr_space_t, unw_regnum_t unwind_reg, unw_word_t* value, int write, 96 void* arg) { 97 if (write == 1) { 98 return -UNW_EINVAL; 99 } 100 BacktraceOffline* backtrace = reinterpret_cast<BacktraceOffline*>(arg); 101 uint64_t reg_value; 102 bool result = backtrace->ReadReg(unwind_reg, ®_value); 103 if (result) { 104 *value = static_cast<unw_word_t>(reg_value); 105 } 106 return result ? 0 : -UNW_EINVAL; 107} 108 109static int AccessFpReg(unw_addr_space_t, unw_regnum_t, unw_fpreg_t*, int, void*) { 110 return -UNW_EINVAL; 111} 112 113static int Resume(unw_addr_space_t, unw_cursor_t*, void*) { 114 return -UNW_EINVAL; 115} 116 117static int GetProcName(unw_addr_space_t, unw_word_t, char*, size_t, unw_word_t*, void*) { 118 return -UNW_EINVAL; 119} 120 121static unw_accessors_t accessors = { 122 .find_proc_info = FindProcInfo, 123 .put_unwind_info = PutUnwindInfo, 124 .get_dyn_info_list_addr = GetDynInfoListAddr, 125 .access_mem = AccessMem, 126 .access_reg = AccessReg, 127 .access_fpreg = AccessFpReg, 128 .resume = Resume, 129 .get_proc_name = GetProcName, 130}; 131 132bool BacktraceOffline::Unwind(size_t num_ignore_frames, ucontext_t* context) { 133 if (context == nullptr) { 134 BACK_LOGW("The context is needed for offline backtracing."); 135 error_ = BACKTRACE_UNWIND_ERROR_NO_CONTEXT; 136 return false; 137 } 138 context_ = context; 139 error_ = BACKTRACE_UNWIND_NO_ERROR; 140 141 unw_addr_space_t addr_space = unw_create_addr_space(&accessors, 0); 142 unw_cursor_t cursor; 143 int ret = unw_init_remote(&cursor, addr_space, this); 144 if (ret != 0) { 145 BACK_LOGW("unw_init_remote failed %d", ret); 146 unw_destroy_addr_space(addr_space); 147 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED; 148 return false; 149 } 150 size_t num_frames = 0; 151 do { 152 unw_word_t pc; 153 ret = unw_get_reg(&cursor, UNW_REG_IP, &pc); 154 if (ret < 0) { 155 BACK_LOGW("Failed to read IP %d", ret); 156 break; 157 } 158 unw_word_t sp; 159 ret = unw_get_reg(&cursor, UNW_REG_SP, &sp); 160 if (ret < 0) { 161 BACK_LOGW("Failed to read SP %d", ret); 162 break; 163 } 164 165 if (num_ignore_frames == 0) { 166 frames_.resize(num_frames + 1); 167 backtrace_frame_data_t* frame = &frames_[num_frames]; 168 frame->num = num_frames; 169 frame->pc = static_cast<uintptr_t>(pc); 170 frame->sp = static_cast<uintptr_t>(sp); 171 frame->stack_size = 0; 172 173 if (num_frames > 0) { 174 backtrace_frame_data_t* prev = &frames_[num_frames - 1]; 175 prev->stack_size = frame->sp - prev->sp; 176 } 177 frame->func_name = GetFunctionName(frame->pc, &frame->func_offset); 178 FillInMap(frame->pc, &frame->map); 179 num_frames++; 180 } else { 181 num_ignore_frames--; 182 } 183 ret = unw_step(&cursor); 184 } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES); 185 186 unw_destroy_addr_space(addr_space); 187 context_ = nullptr; 188 return true; 189} 190 191bool BacktraceOffline::ReadWord(uintptr_t ptr, word_t* out_value) { 192 size_t bytes_read = Read(ptr, reinterpret_cast<uint8_t*>(out_value), sizeof(word_t)); 193 return bytes_read == sizeof(word_t); 194} 195 196size_t BacktraceOffline::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) { 197 // Normally, libunwind needs stack information and call frame information to do remote unwinding. 198 // If call frame information is stored in .debug_frame, libunwind can read it from file 199 // by itself. If call frame information is stored in .eh_frame, we need to provide data in 200 // .eh_frame/.eh_frame_hdr sections. 201 // The order of readings below doesn't matter, as the spaces don't overlap with each other. 202 size_t read_size = eh_frame_hdr_space_.Read(addr, buffer, bytes); 203 if (read_size != 0) { 204 return read_size; 205 } 206 read_size = eh_frame_space_.Read(addr, buffer, bytes); 207 if (read_size != 0) { 208 return read_size; 209 } 210 read_size = stack_space_.Read(addr, buffer, bytes); 211 return read_size; 212} 213 214static bool FileOffsetToVaddr( 215 const std::vector<DebugFrameInfo::EhFrame::ProgramHeader>& program_headers, 216 uint64_t file_offset, uint64_t* vaddr) { 217 for (auto& header : program_headers) { 218 if (file_offset >= header.file_offset && file_offset < header.file_offset + header.file_size) { 219 // TODO: Consider load_bias? 220 *vaddr = file_offset - header.file_offset + header.vaddr; 221 return true; 222 } 223 } 224 return false; 225} 226 227bool BacktraceOffline::FindProcInfo(unw_addr_space_t addr_space, uint64_t ip, 228 unw_proc_info_t* proc_info, int need_unwind_info) { 229 backtrace_map_t map; 230 FillInMap(ip, &map); 231 if (!BacktraceMap::IsValid(map)) { 232 return false; 233 } 234 const std::string& filename = map.name; 235 DebugFrameInfo* debug_frame = GetDebugFrameInFile(filename); 236 if (debug_frame == nullptr) { 237 return false; 238 } 239 if (debug_frame->is_eh_frame) { 240 uint64_t ip_offset = ip - map.start + map.offset; 241 uint64_t ip_vaddr; // vaddr in the elf file. 242 bool result = FileOffsetToVaddr(debug_frame->eh_frame.program_headers, ip_offset, &ip_vaddr); 243 if (!result) { 244 return false; 245 } 246 // Calculate the addresses where .eh_frame_hdr and .eh_frame stay when the process was running. 247 eh_frame_hdr_space_.start = (ip - ip_vaddr) + debug_frame->eh_frame.eh_frame_hdr_vaddr; 248 eh_frame_hdr_space_.end = 249 eh_frame_hdr_space_.start + debug_frame->eh_frame.eh_frame_hdr_data.size(); 250 eh_frame_hdr_space_.data = debug_frame->eh_frame.eh_frame_hdr_data.data(); 251 252 eh_frame_space_.start = (ip - ip_vaddr) + debug_frame->eh_frame.eh_frame_vaddr; 253 eh_frame_space_.end = eh_frame_space_.start + debug_frame->eh_frame.eh_frame_data.size(); 254 eh_frame_space_.data = debug_frame->eh_frame.eh_frame_data.data(); 255 256 unw_dyn_info di; 257 memset(&di, '\0', sizeof(di)); 258 di.start_ip = map.start; 259 di.end_ip = map.end; 260 di.format = UNW_INFO_FORMAT_REMOTE_TABLE; 261 di.u.rti.name_ptr = 0; 262 di.u.rti.segbase = eh_frame_hdr_space_.start; 263 di.u.rti.table_data = 264 eh_frame_hdr_space_.start + debug_frame->eh_frame.fde_table_offset_in_eh_frame_hdr; 265 di.u.rti.table_len = (eh_frame_hdr_space_.end - di.u.rti.table_data) / sizeof(unw_word_t); 266 int ret = dwarf_search_unwind_table(addr_space, ip, &di, proc_info, need_unwind_info, this); 267 return ret == 0; 268 } 269 270 eh_frame_hdr_space_.Clear(); 271 eh_frame_space_.Clear(); 272 unw_dyn_info_t di; 273 unw_word_t segbase = map.start - map.offset; 274 int found = dwarf_find_debug_frame(0, &di, ip, segbase, filename.c_str(), map.start, map.end); 275 if (found == 1) { 276 int ret = dwarf_search_unwind_table(addr_space, ip, &di, proc_info, need_unwind_info, this); 277 return ret == 0; 278 } 279 return false; 280} 281 282bool BacktraceOffline::ReadReg(size_t reg, uint64_t* value) { 283 bool result = true; 284#if defined(__arm__) 285 switch (reg) { 286 case UNW_ARM_R0: 287 *value = context_->uc_mcontext.arm_r0; 288 break; 289 case UNW_ARM_R1: 290 *value = context_->uc_mcontext.arm_r1; 291 break; 292 case UNW_ARM_R2: 293 *value = context_->uc_mcontext.arm_r2; 294 break; 295 case UNW_ARM_R3: 296 *value = context_->uc_mcontext.arm_r3; 297 break; 298 case UNW_ARM_R4: 299 *value = context_->uc_mcontext.arm_r4; 300 break; 301 case UNW_ARM_R5: 302 *value = context_->uc_mcontext.arm_r5; 303 break; 304 case UNW_ARM_R6: 305 *value = context_->uc_mcontext.arm_r6; 306 break; 307 case UNW_ARM_R7: 308 *value = context_->uc_mcontext.arm_r7; 309 break; 310 case UNW_ARM_R8: 311 *value = context_->uc_mcontext.arm_r8; 312 break; 313 case UNW_ARM_R9: 314 *value = context_->uc_mcontext.arm_r9; 315 break; 316 case UNW_ARM_R10: 317 *value = context_->uc_mcontext.arm_r10; 318 break; 319 case UNW_ARM_R11: 320 *value = context_->uc_mcontext.arm_fp; 321 break; 322 case UNW_ARM_R12: 323 *value = context_->uc_mcontext.arm_ip; 324 break; 325 case UNW_ARM_R13: 326 *value = context_->uc_mcontext.arm_sp; 327 break; 328 case UNW_ARM_R14: 329 *value = context_->uc_mcontext.arm_lr; 330 break; 331 case UNW_ARM_R15: 332 *value = context_->uc_mcontext.arm_pc; 333 break; 334 default: 335 result = false; 336 } 337#elif defined(__aarch64__) 338 if (reg <= UNW_AARCH64_PC) { 339 *value = context_->uc_mcontext.regs[reg]; 340 } else { 341 result = false; 342 } 343#elif defined(__x86_64__) 344 switch (reg) { 345 case UNW_X86_64_R8: 346 *value = context_->uc_mcontext.gregs[REG_R8]; 347 break; 348 case UNW_X86_64_R9: 349 *value = context_->uc_mcontext.gregs[REG_R9]; 350 break; 351 case UNW_X86_64_R10: 352 *value = context_->uc_mcontext.gregs[REG_R10]; 353 break; 354 case UNW_X86_64_R11: 355 *value = context_->uc_mcontext.gregs[REG_R11]; 356 break; 357 case UNW_X86_64_R12: 358 *value = context_->uc_mcontext.gregs[REG_R12]; 359 break; 360 case UNW_X86_64_R13: 361 *value = context_->uc_mcontext.gregs[REG_R13]; 362 break; 363 case UNW_X86_64_R14: 364 *value = context_->uc_mcontext.gregs[REG_R14]; 365 break; 366 case UNW_X86_64_R15: 367 *value = context_->uc_mcontext.gregs[REG_R15]; 368 break; 369 case UNW_X86_64_RDI: 370 *value = context_->uc_mcontext.gregs[REG_RDI]; 371 break; 372 case UNW_X86_64_RSI: 373 *value = context_->uc_mcontext.gregs[REG_RSI]; 374 break; 375 case UNW_X86_64_RBP: 376 *value = context_->uc_mcontext.gregs[REG_RBP]; 377 break; 378 case UNW_X86_64_RBX: 379 *value = context_->uc_mcontext.gregs[REG_RBX]; 380 break; 381 case UNW_X86_64_RDX: 382 *value = context_->uc_mcontext.gregs[REG_RDX]; 383 break; 384 case UNW_X86_64_RAX: 385 *value = context_->uc_mcontext.gregs[REG_RAX]; 386 break; 387 case UNW_X86_64_RCX: 388 *value = context_->uc_mcontext.gregs[REG_RCX]; 389 break; 390 case UNW_X86_64_RSP: 391 *value = context_->uc_mcontext.gregs[REG_RSP]; 392 break; 393 case UNW_X86_64_RIP: 394 *value = context_->uc_mcontext.gregs[REG_RIP]; 395 break; 396 default: 397 result = false; 398 } 399#elif defined(__i386__) 400 switch (reg) { 401 case UNW_X86_GS: 402 *value = context_->uc_mcontext.gregs[REG_GS]; 403 break; 404 case UNW_X86_FS: 405 *value = context_->uc_mcontext.gregs[REG_FS]; 406 break; 407 case UNW_X86_ES: 408 *value = context_->uc_mcontext.gregs[REG_ES]; 409 break; 410 case UNW_X86_DS: 411 *value = context_->uc_mcontext.gregs[REG_DS]; 412 break; 413 case UNW_X86_EAX: 414 *value = context_->uc_mcontext.gregs[REG_EAX]; 415 break; 416 case UNW_X86_EBX: 417 *value = context_->uc_mcontext.gregs[REG_EBX]; 418 break; 419 case UNW_X86_ECX: 420 *value = context_->uc_mcontext.gregs[REG_ECX]; 421 break; 422 case UNW_X86_EDX: 423 *value = context_->uc_mcontext.gregs[REG_EDX]; 424 break; 425 case UNW_X86_ESI: 426 *value = context_->uc_mcontext.gregs[REG_ESI]; 427 break; 428 case UNW_X86_EDI: 429 *value = context_->uc_mcontext.gregs[REG_EDI]; 430 break; 431 case UNW_X86_EBP: 432 *value = context_->uc_mcontext.gregs[REG_EBP]; 433 break; 434 case UNW_X86_EIP: 435 *value = context_->uc_mcontext.gregs[REG_EIP]; 436 break; 437 case UNW_X86_ESP: 438 *value = context_->uc_mcontext.gregs[REG_ESP]; 439 break; 440 case UNW_X86_TRAPNO: 441 *value = context_->uc_mcontext.gregs[REG_TRAPNO]; 442 break; 443 case UNW_X86_CS: 444 *value = context_->uc_mcontext.gregs[REG_CS]; 445 break; 446 case UNW_X86_EFLAGS: 447 *value = context_->uc_mcontext.gregs[REG_EFL]; 448 break; 449 case UNW_X86_SS: 450 *value = context_->uc_mcontext.gregs[REG_SS]; 451 break; 452 default: 453 result = false; 454 } 455#endif 456 return result; 457} 458 459std::string BacktraceOffline::GetFunctionNameRaw(uintptr_t, uintptr_t* offset) { 460 // We don't have enough information to support this. And it is expensive. 461 *offset = 0; 462 return ""; 463} 464 465std::unordered_map<std::string, std::unique_ptr<DebugFrameInfo>> BacktraceOffline::debug_frames_; 466std::unordered_set<std::string> BacktraceOffline::debug_frame_missing_files_; 467 468static DebugFrameInfo* ReadDebugFrameFromFile(const std::string& filename); 469 470DebugFrameInfo* BacktraceOffline::GetDebugFrameInFile(const std::string& filename) { 471 if (cache_file_) { 472 auto it = debug_frames_.find(filename); 473 if (it != debug_frames_.end()) { 474 return it->second.get(); 475 } 476 if (debug_frame_missing_files_.find(filename) != debug_frame_missing_files_.end()) { 477 return nullptr; 478 } 479 } 480 DebugFrameInfo* debug_frame = ReadDebugFrameFromFile(filename); 481 if (cache_file_) { 482 if (debug_frame != nullptr) { 483 debug_frames_.emplace(filename, std::unique_ptr<DebugFrameInfo>(debug_frame)); 484 } else { 485 debug_frame_missing_files_.insert(filename); 486 } 487 } else { 488 if (last_debug_frame_ != nullptr) { 489 delete last_debug_frame_; 490 } 491 last_debug_frame_ = debug_frame; 492 } 493 return debug_frame; 494} 495 496static bool OmitEncodedValue(uint8_t encode, const uint8_t*& p) { 497 if (encode == DW_EH_PE_omit) { 498 return 0; 499 } 500 uint8_t format = encode & 0x0f; 501 switch (format) { 502 case DW_EH_PE_ptr: 503 p += sizeof(unw_word_t); 504 break; 505 case DW_EH_PE_uleb128: 506 case DW_EH_PE_sleb128: 507 while ((*p & 0x80) != 0) { 508 ++p; 509 } 510 ++p; 511 break; 512 case DW_EH_PE_udata2: 513 case DW_EH_PE_sdata2: 514 p += 2; 515 break; 516 case DW_EH_PE_udata4: 517 case DW_EH_PE_sdata4: 518 p += 4; 519 break; 520 case DW_EH_PE_udata8: 521 case DW_EH_PE_sdata8: 522 p += 8; 523 break; 524 default: 525 return false; 526 } 527 return true; 528} 529 530static bool GetFdeTableOffsetInEhFrameHdr(const std::vector<uint8_t>& data, 531 uint64_t* table_offset_in_eh_frame_hdr) { 532 const uint8_t* p = data.data(); 533 const uint8_t* end = p + data.size(); 534 if (p + 4 > end) { 535 return false; 536 } 537 uint8_t version = *p++; 538 if (version != 1) { 539 return false; 540 } 541 uint8_t eh_frame_ptr_encode = *p++; 542 uint8_t fde_count_encode = *p++; 543 uint8_t fde_table_encode = *p++; 544 545 if (fde_table_encode != (DW_EH_PE_datarel | DW_EH_PE_sdata4)) { 546 return false; 547 } 548 549 if (!OmitEncodedValue(eh_frame_ptr_encode, p) || !OmitEncodedValue(fde_count_encode, p)) { 550 return false; 551 } 552 if (p >= end) { 553 return false; 554 } 555 *table_offset_in_eh_frame_hdr = p - data.data(); 556 return true; 557} 558 559using ProgramHeader = DebugFrameInfo::EhFrame::ProgramHeader; 560 561template <class ELFT> 562DebugFrameInfo* ReadDebugFrameFromELFFile(const llvm::object::ELFFile<ELFT>* elf) { 563 bool has_eh_frame_hdr = false; 564 uint64_t eh_frame_hdr_vaddr = 0; 565 std::vector<uint8_t> eh_frame_hdr_data; 566 bool has_eh_frame = false; 567 uint64_t eh_frame_vaddr = 0; 568 std::vector<uint8_t> eh_frame_data; 569 570 for (auto it = elf->section_begin(); it != elf->section_end(); ++it) { 571 llvm::ErrorOr<llvm::StringRef> name = elf->getSectionName(&*it); 572 if (name) { 573 if (name.get() == ".debug_frame") { 574 DebugFrameInfo* debug_frame = new DebugFrameInfo; 575 debug_frame->is_eh_frame = false; 576 return debug_frame; 577 } 578 if (name.get() == ".eh_frame_hdr") { 579 has_eh_frame_hdr = true; 580 eh_frame_hdr_vaddr = it->sh_addr; 581 llvm::ErrorOr<llvm::ArrayRef<uint8_t>> data = elf->getSectionContents(&*it); 582 if (data) { 583 eh_frame_hdr_data.insert(eh_frame_hdr_data.begin(), data->data(), 584 data->data() + data->size()); 585 } else { 586 return nullptr; 587 } 588 } else if (name.get() == ".eh_frame") { 589 has_eh_frame = true; 590 eh_frame_vaddr = it->sh_addr; 591 llvm::ErrorOr<llvm::ArrayRef<uint8_t>> data = elf->getSectionContents(&*it); 592 if (data) { 593 eh_frame_data.insert(eh_frame_data.begin(), data->data(), data->data() + data->size()); 594 } else { 595 return nullptr; 596 } 597 } 598 } 599 } 600 if (!(has_eh_frame_hdr && has_eh_frame)) { 601 return nullptr; 602 } 603 uint64_t fde_table_offset; 604 if (!GetFdeTableOffsetInEhFrameHdr(eh_frame_hdr_data, &fde_table_offset)) { 605 return nullptr; 606 } 607 608 std::vector<ProgramHeader> program_headers; 609 for (auto it = elf->program_header_begin(); it != elf->program_header_end(); ++it) { 610 ProgramHeader header; 611 header.vaddr = it->p_vaddr; 612 header.file_offset = it->p_offset; 613 header.file_size = it->p_filesz; 614 program_headers.push_back(header); 615 } 616 DebugFrameInfo* debug_frame = new DebugFrameInfo; 617 debug_frame->is_eh_frame = true; 618 debug_frame->eh_frame.eh_frame_hdr_vaddr = eh_frame_hdr_vaddr; 619 debug_frame->eh_frame.eh_frame_vaddr = eh_frame_vaddr; 620 debug_frame->eh_frame.fde_table_offset_in_eh_frame_hdr = fde_table_offset; 621 debug_frame->eh_frame.eh_frame_hdr_data = std::move(eh_frame_hdr_data); 622 debug_frame->eh_frame.eh_frame_data = std::move(eh_frame_data); 623 debug_frame->eh_frame.program_headers = program_headers; 624 return debug_frame; 625} 626 627static bool IsValidElfPath(const std::string& filename) { 628 static const char elf_magic[] = {0x7f, 'E', 'L', 'F'}; 629 630 struct stat st; 631 if (stat(filename.c_str(), &st) != 0 || !S_ISREG(st.st_mode)) { 632 return false; 633 } 634 FILE* fp = fopen(filename.c_str(), "reb"); 635 if (fp == nullptr) { 636 return false; 637 } 638 char buf[4]; 639 if (fread(buf, 4, 1, fp) != 1) { 640 fclose(fp); 641 return false; 642 } 643 fclose(fp); 644 return memcmp(buf, elf_magic, 4) == 0; 645} 646 647static bool IsValidApkPath(const std::string& apk_path) { 648 static const char zip_preamble[] = {0x50, 0x4b, 0x03, 0x04}; 649 struct stat st; 650 if (stat(apk_path.c_str(), &st) != 0 || !S_ISREG(st.st_mode)) { 651 return false; 652 } 653 FILE* fp = fopen(apk_path.c_str(), "reb"); 654 if (fp == nullptr) { 655 return false; 656 } 657 char buf[4]; 658 if (fread(buf, 4, 1, fp) != 1) { 659 fclose(fp); 660 return false; 661 } 662 fclose(fp); 663 return memcmp(buf, zip_preamble, 4) == 0; 664} 665 666class ScopedZiparchiveHandle { 667 public: 668 ScopedZiparchiveHandle(ZipArchiveHandle handle) : handle_(handle) { 669 } 670 671 ~ScopedZiparchiveHandle() { 672 CloseArchive(handle_); 673 } 674 675 private: 676 ZipArchiveHandle handle_; 677}; 678 679llvm::object::OwningBinary<llvm::object::Binary> OpenEmbeddedElfFile(const std::string& filename) { 680 llvm::object::OwningBinary<llvm::object::Binary> nothing; 681 size_t pos = filename.find("!/"); 682 if (pos == std::string::npos) { 683 return nothing; 684 } 685 std::string apk_file = filename.substr(0, pos); 686 std::string elf_file = filename.substr(pos + 2); 687 if (!IsValidApkPath(apk_file)) { 688 BACK_LOGW("%s is not a valid apk file", apk_file.c_str()); 689 return nothing; 690 } 691 ZipArchiveHandle handle; 692 int32_t ret_code = OpenArchive(apk_file.c_str(), &handle); 693 if (ret_code != 0) { 694 CloseArchive(handle); 695 BACK_LOGW("failed to open archive %s: %s", apk_file.c_str(), ErrorCodeString(ret_code)); 696 return nothing; 697 } 698 ScopedZiparchiveHandle scoped_handle(handle); 699 ZipEntry zentry; 700 ret_code = FindEntry(handle, ZipString(elf_file.c_str()), &zentry); 701 if (ret_code != 0) { 702 BACK_LOGW("failed to find %s in %s: %s", elf_file.c_str(), apk_file.c_str(), 703 ErrorCodeString(ret_code)); 704 return nothing; 705 } 706 if (zentry.method != kCompressStored || zentry.compressed_length != zentry.uncompressed_length) { 707 BACK_LOGW("%s is compressed in %s, which doesn't support running directly", elf_file.c_str(), 708 apk_file.c_str()); 709 return nothing; 710 } 711 auto buffer_or_err = llvm::MemoryBuffer::getOpenFileSlice(GetFileDescriptor(handle), apk_file, 712 zentry.uncompressed_length, 713 zentry.offset); 714 if (!buffer_or_err) { 715 BACK_LOGW("failed to read %s in %s: %s", elf_file.c_str(), apk_file.c_str(), 716 buffer_or_err.getError().message().c_str()); 717 return nothing; 718 } 719 auto binary_or_err = llvm::object::createBinary(buffer_or_err.get()->getMemBufferRef()); 720 if (!binary_or_err) { 721 BACK_LOGW("failed to create binary for %s in %s: %s", elf_file.c_str(), apk_file.c_str(), 722 binary_or_err.getError().message().c_str()); 723 return nothing; 724 } 725 return llvm::object::OwningBinary<llvm::object::Binary>(std::move(binary_or_err.get()), 726 std::move(buffer_or_err.get())); 727} 728 729static DebugFrameInfo* ReadDebugFrameFromFile(const std::string& filename) { 730 llvm::object::OwningBinary<llvm::object::Binary> owning_binary; 731 if (filename.find("!/") != std::string::npos) { 732 owning_binary = OpenEmbeddedElfFile(filename); 733 } else { 734 if (!IsValidElfPath(filename)) { 735 return nullptr; 736 } 737 auto binary_or_err = llvm::object::createBinary(llvm::StringRef(filename)); 738 if (!binary_or_err) { 739 return nullptr; 740 } 741 owning_binary = std::move(binary_or_err.get()); 742 } 743 llvm::object::Binary* binary = owning_binary.getBinary(); 744 auto obj = llvm::dyn_cast<llvm::object::ObjectFile>(binary); 745 if (obj == nullptr) { 746 return nullptr; 747 } 748 if (auto elf = llvm::dyn_cast<llvm::object::ELF32LEObjectFile>(obj)) { 749 return ReadDebugFrameFromELFFile(elf->getELFFile()); 750 } 751 if (auto elf = llvm::dyn_cast<llvm::object::ELF64LEObjectFile>(obj)) { 752 return ReadDebugFrameFromELFFile(elf->getELFFile()); 753 } 754 return nullptr; 755} 756 757Backtrace* Backtrace::CreateOffline(pid_t pid, pid_t tid, BacktraceMap* map, 758 const backtrace_stackinfo_t& stack, bool cache_file) { 759 return new BacktraceOffline(pid, tid, map, stack, cache_file); 760} 761