diff options
Diffstat (limited to 'libc/bionic/execinfo.cpp')
| -rw-r--r-- | libc/bionic/execinfo.cpp | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/libc/bionic/execinfo.cpp b/libc/bionic/execinfo.cpp new file mode 100644 index 000000000..d129f7cae --- /dev/null +++ b/libc/bionic/execinfo.cpp @@ -0,0 +1,187 @@ +/* + * Copyright (C) 2012 The Android Open Source Project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <dlfcn.h> +#include <execinfo.h> +#include <inttypes.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/mman.h> +#include <unistd.h> +#include <unwind.h> + +#include "private/ScopedFd.h" + +struct StackState { + void** frames; + int frame_count; + int cur_frame = 0; + + StackState(void** frames, int frame_count) : frames(frames), frame_count(frame_count) {} +}; + +static _Unwind_Reason_Code TraceFunction(_Unwind_Context* context, void* arg) { + // The instruction pointer is pointing at the instruction after the return + // call on all architectures. + // Modify the pc to point at the real function. + uintptr_t ip = _Unwind_GetIP(context); + if (ip != 0) { +#if defined(__arm__) + // If the ip is suspiciously low, do nothing to avoid a segfault trying + // to access this memory. + if (ip >= 4096) { + // Check bits [15:11] of the first halfword assuming the instruction + // is 32 bits long. If the bits are any of these values, then our + // assumption was correct: + // b11101 + // b11110 + // b11111 + // Otherwise, this is a 16 bit instruction. + uint16_t value = (*reinterpret_cast<uint16_t*>(ip - 2)) >> 11; + if (value == 0x1f || value == 0x1e || value == 0x1d) { + ip -= 4; + } else { + ip -= 2; + } + } +#elif defined(__aarch64__) + // All instructions are 4 bytes long, skip back one instruction. + ip -= 4; +#elif defined(__i386__) || defined(__x86_64__) + // It's difficult to decode exactly where the previous instruction is, + // so subtract 1 to estimate where the instruction lives. + ip--; +#endif + } + + StackState* state = static_cast<StackState*>(arg); + state->frames[state->cur_frame++] = reinterpret_cast<void*>(ip); + return (state->cur_frame >= state->frame_count) ? _URC_END_OF_STACK : _URC_NO_REASON; +} + +int backtrace(void** buffer, int size) { + if (size <= 0) { + return 0; + } + + StackState state(buffer, size); + _Unwind_Backtrace(TraceFunction, &state); + return state.cur_frame; +} + +char** backtrace_symbols(void* const* buffer, int size) { + if (size <= 0) { + return nullptr; + } + // Do this calculation first in case the user passes in a bad value. + size_t ptr_size; + if (__builtin_mul_overflow(sizeof(char*), size, &ptr_size)) { + return nullptr; + } + + ScopedFd fd(memfd_create("backtrace_symbols_fd", MFD_CLOEXEC)); + if (fd.get() == -1) { + return nullptr; + } + backtrace_symbols_fd(buffer, size, fd.get()); + + // Get the size of the file. + off_t file_size = lseek(fd.get(), 0, SEEK_END); + if (file_size <= 0) { + return nullptr; + } + + // The interface for backtrace_symbols indicates that only the single + // returned pointer must be freed by the caller. Therefore, allocate a + // buffer that includes the memory for the strings and all of the pointers. + // Add one byte at the end just in case the file didn't end with a '\n'. + size_t symbol_data_size; + if (__builtin_add_overflow(ptr_size, file_size, &symbol_data_size) || + __builtin_add_overflow(symbol_data_size, 1, &symbol_data_size)) { + return nullptr; + } + + uint8_t* symbol_data = reinterpret_cast<uint8_t*>(malloc(symbol_data_size)); + if (symbol_data == nullptr) { + return nullptr; + } + + // Copy the string data into the buffer. + char* cur_string = reinterpret_cast<char*>(&symbol_data[ptr_size]); + // If this fails, the read won't read back the correct number of bytes. + lseek(fd.get(), 0, SEEK_SET); + ssize_t num_read = read(fd.get(), cur_string, file_size); + fd.reset(-1); + if (num_read != file_size) { + free(symbol_data); + return nullptr; + } + + // Make sure the last character in the file is '\n'. + if (cur_string[file_size] != '\n') { + cur_string[file_size++] = '\n'; + } + + for (int i = 0; i < size; i++) { + (reinterpret_cast<char**>(symbol_data))[i] = cur_string; + cur_string = strchr(cur_string, '\n'); + if (cur_string == nullptr) { + free(symbol_data); + return nullptr; + } + cur_string[0] = '\0'; + cur_string++; + } + return reinterpret_cast<char**>(symbol_data); +} + +// This function should do no allocations if possible. +void backtrace_symbols_fd(void* const* buffer, int size, int fd) { + if (size <= 0 || fd < 0) { + return; + } + + for (int frame_num = 0; frame_num < size; frame_num++) { + void* address = buffer[frame_num]; + Dl_info info; + if (dladdr(address, &info) != 0) { + if (info.dli_fname != nullptr) { + write(fd, info.dli_fname, strlen(info.dli_fname)); + } + if (info.dli_sname != nullptr) { + dprintf(fd, "(%s+0x%" PRIxPTR ") ", info.dli_sname, + reinterpret_cast<uintptr_t>(address) - reinterpret_cast<uintptr_t>(info.dli_saddr)); + } else { + dprintf(fd, "(+%p) ", info.dli_saddr); + } + } + + dprintf(fd, "[%p]\n", address); + } +} |