967 lines
32 KiB
C++
967 lines
32 KiB
C++
// Copyright (c) 2006, Google Inc.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// Author: Satoru Takabayashi
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// Stack-footprint reduction work done by Raksit Ashok
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//
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// Implementation note:
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//
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// We don't use heaps but only use stacks. We want to reduce the
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// stack consumption so that the symbolizer can run on small stacks.
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//
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// Here are some numbers collected with GCC 4.1.0 on x86:
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// - sizeof(Elf32_Sym) = 16
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// - sizeof(Elf32_Shdr) = 40
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// - sizeof(Elf64_Sym) = 24
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// - sizeof(Elf64_Shdr) = 64
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//
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// This implementation is intended to be async-signal-safe but uses
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// some functions which are not guaranteed to be so, such as memchr()
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// and memmove(). We assume they are async-signal-safe.
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//
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// Additional header can be specified by the GLOG_BUILD_CONFIG_INCLUDE
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// macro to add platform specific defines (e.g. OS_OPENBSD).
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#ifdef GLOG_BUILD_CONFIG_INCLUDE
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#include GLOG_BUILD_CONFIG_INCLUDE
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#endif // GLOG_BUILD_CONFIG_INCLUDE
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#include "utilities.h"
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#if defined(HAVE_SYMBOLIZE)
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#include <string.h>
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#include <algorithm>
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#include <limits>
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#include "symbolize.h"
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#include "demangle.h"
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_START_GOOGLE_NAMESPACE_
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// We don't use assert() since it's not guaranteed to be
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// async-signal-safe. Instead we define a minimal assertion
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// macro. So far, we don't need pretty printing for __FILE__, etc.
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// A wrapper for abort() to make it callable in ? :.
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static int AssertFail() {
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abort();
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return 0; // Should not reach.
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}
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#define SAFE_ASSERT(expr) ((expr) ? 0 : AssertFail())
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static SymbolizeCallback g_symbolize_callback = NULL;
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void InstallSymbolizeCallback(SymbolizeCallback callback) {
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g_symbolize_callback = callback;
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}
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static SymbolizeOpenObjectFileCallback g_symbolize_open_object_file_callback =
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NULL;
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void InstallSymbolizeOpenObjectFileCallback(
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SymbolizeOpenObjectFileCallback callback) {
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g_symbolize_open_object_file_callback = callback;
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}
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// This function wraps the Demangle function to provide an interface
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// where the input symbol is demangled in-place.
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// To keep stack consumption low, we would like this function to not
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// get inlined.
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static ATTRIBUTE_NOINLINE void DemangleInplace(char *out, int out_size) {
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char demangled[256]; // Big enough for sane demangled symbols.
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if (Demangle(out, demangled, sizeof(demangled))) {
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// Demangling succeeded. Copy to out if the space allows.
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size_t len = strlen(demangled);
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if (len + 1 <= (size_t)out_size) { // +1 for '\0'.
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SAFE_ASSERT(len < sizeof(demangled));
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memmove(out, demangled, len + 1);
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}
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}
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}
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_END_GOOGLE_NAMESPACE_
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#if defined(__ELF__)
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#if defined(HAVE_DLFCN_H)
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#include <dlfcn.h>
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#endif
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#if defined(OS_OPENBSD)
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#include <sys/exec_elf.h>
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#else
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#include <elf.h>
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#endif
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stddef.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "symbolize.h"
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#include "config.h"
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#include "glog/raw_logging.h"
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// Re-runs fn until it doesn't cause EINTR.
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#define NO_INTR(fn) do {} while ((fn) < 0 && errno == EINTR)
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_START_GOOGLE_NAMESPACE_
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// Read up to "count" bytes from "offset" in the file pointed by file
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// descriptor "fd" into the buffer starting at "buf" while handling short reads
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// and EINTR. On success, return the number of bytes read. Otherwise, return
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// -1.
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static ssize_t ReadFromOffset(const int fd, void *buf, const size_t count,
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const off_t offset) {
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SAFE_ASSERT(fd >= 0);
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SAFE_ASSERT(count <= std::numeric_limits<ssize_t>::max());
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char *buf0 = reinterpret_cast<char *>(buf);
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ssize_t num_bytes = 0;
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while (num_bytes < count) {
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ssize_t len;
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NO_INTR(len = pread(fd, buf0 + num_bytes, count - num_bytes,
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offset + num_bytes));
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if (len < 0) { // There was an error other than EINTR.
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return -1;
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}
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if (len == 0) { // Reached EOF.
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break;
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}
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num_bytes += len;
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}
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SAFE_ASSERT(num_bytes <= count);
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return num_bytes;
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}
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// Try reading exactly "count" bytes from "offset" bytes in a file
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// pointed by "fd" into the buffer starting at "buf" while handling
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// short reads and EINTR. On success, return true. Otherwise, return
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// false.
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static bool ReadFromOffsetExact(const int fd, void *buf,
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const size_t count, const off_t offset) {
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ssize_t len = ReadFromOffset(fd, buf, count, offset);
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return len == count;
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}
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// Returns elf_header.e_type if the file pointed by fd is an ELF binary.
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static int FileGetElfType(const int fd) {
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ElfW(Ehdr) elf_header;
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if (!ReadFromOffsetExact(fd, &elf_header, sizeof(elf_header), 0)) {
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return -1;
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}
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if (memcmp(elf_header.e_ident, ELFMAG, SELFMAG) != 0) {
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return -1;
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}
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return elf_header.e_type;
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}
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// Read the section headers in the given ELF binary, and if a section
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// of the specified type is found, set the output to this section header
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// and return true. Otherwise, return false.
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// To keep stack consumption low, we would like this function to not get
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// inlined.
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static ATTRIBUTE_NOINLINE bool
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GetSectionHeaderByType(const int fd, ElfW(Half) sh_num, const off_t sh_offset,
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ElfW(Word) type, ElfW(Shdr) *out) {
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// Read at most 16 section headers at a time to save read calls.
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ElfW(Shdr) buf[16];
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for (int i = 0; i < sh_num;) {
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const ssize_t num_bytes_left = (sh_num - i) * sizeof(buf[0]);
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const ssize_t num_bytes_to_read =
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(sizeof(buf) > num_bytes_left) ? num_bytes_left : sizeof(buf);
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const ssize_t len = ReadFromOffset(fd, buf, num_bytes_to_read,
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sh_offset + i * sizeof(buf[0]));
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if (len == -1) {
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return false;
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}
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SAFE_ASSERT(len % sizeof(buf[0]) == 0);
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const ssize_t num_headers_in_buf = len / sizeof(buf[0]);
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SAFE_ASSERT(num_headers_in_buf <= sizeof(buf) / sizeof(buf[0]));
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for (int j = 0; j < num_headers_in_buf; ++j) {
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if (buf[j].sh_type == type) {
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*out = buf[j];
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return true;
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}
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}
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i += num_headers_in_buf;
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}
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return false;
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}
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// There is no particular reason to limit section name to 63 characters,
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// but there has (as yet) been no need for anything longer either.
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const int kMaxSectionNameLen = 64;
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// name_len should include terminating '\0'.
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bool GetSectionHeaderByName(int fd, const char *name, size_t name_len,
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ElfW(Shdr) *out) {
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ElfW(Ehdr) elf_header;
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if (!ReadFromOffsetExact(fd, &elf_header, sizeof(elf_header), 0)) {
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return false;
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}
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ElfW(Shdr) shstrtab;
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off_t shstrtab_offset = (elf_header.e_shoff +
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elf_header.e_shentsize * elf_header.e_shstrndx);
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if (!ReadFromOffsetExact(fd, &shstrtab, sizeof(shstrtab), shstrtab_offset)) {
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return false;
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}
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for (int i = 0; i < elf_header.e_shnum; ++i) {
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off_t section_header_offset = (elf_header.e_shoff +
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elf_header.e_shentsize * i);
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if (!ReadFromOffsetExact(fd, out, sizeof(*out), section_header_offset)) {
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return false;
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}
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char header_name[kMaxSectionNameLen];
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if (sizeof(header_name) < name_len) {
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RAW_LOG(WARNING, "Section name '%s' is too long (%" PRIuS "); "
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"section will not be found (even if present).", name, name_len);
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// No point in even trying.
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return false;
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}
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off_t name_offset = shstrtab.sh_offset + out->sh_name;
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ssize_t n_read = ReadFromOffset(fd, &header_name, name_len, name_offset);
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if (n_read == -1) {
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return false;
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} else if (n_read != name_len) {
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// Short read -- name could be at end of file.
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continue;
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}
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if (memcmp(header_name, name, name_len) == 0) {
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return true;
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}
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}
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return false;
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}
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// Read a symbol table and look for the symbol containing the
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// pc. Iterate over symbols in a symbol table and look for the symbol
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// containing "pc". On success, return true and write the symbol name
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// to out. Otherwise, return false.
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// To keep stack consumption low, we would like this function to not get
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// inlined.
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static ATTRIBUTE_NOINLINE bool
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FindSymbol(uint64_t pc, const int fd, char *out, int out_size,
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uint64_t symbol_offset, const ElfW(Shdr) *strtab,
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const ElfW(Shdr) *symtab) {
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if (symtab == NULL) {
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return false;
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}
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const int num_symbols = symtab->sh_size / symtab->sh_entsize;
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for (int i = 0; i < num_symbols;) {
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off_t offset = symtab->sh_offset + i * symtab->sh_entsize;
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// If we are reading Elf64_Sym's, we want to limit this array to
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// 32 elements (to keep stack consumption low), otherwise we can
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// have a 64 element Elf32_Sym array.
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#if __WORDSIZE == 64
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#define NUM_SYMBOLS 32
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#else
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#define NUM_SYMBOLS 64
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#endif
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// Read at most NUM_SYMBOLS symbols at once to save read() calls.
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ElfW(Sym) buf[NUM_SYMBOLS];
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int num_symbols_to_read = std::min(NUM_SYMBOLS, num_symbols - i);
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const ssize_t len =
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ReadFromOffset(fd, &buf, sizeof(buf[0]) * num_symbols_to_read, offset);
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SAFE_ASSERT(len % sizeof(buf[0]) == 0);
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const ssize_t num_symbols_in_buf = len / sizeof(buf[0]);
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SAFE_ASSERT(num_symbols_in_buf <= num_symbols_to_read);
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for (int j = 0; j < num_symbols_in_buf; ++j) {
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const ElfW(Sym)& symbol = buf[j];
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uint64_t start_address = symbol.st_value;
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start_address += symbol_offset;
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uint64_t end_address = start_address + symbol.st_size;
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if (symbol.st_value != 0 && // Skip null value symbols.
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symbol.st_shndx != 0 && // Skip undefined symbols.
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start_address <= pc && pc < end_address) {
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ssize_t len1 = ReadFromOffset(fd, out, out_size,
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strtab->sh_offset + symbol.st_name);
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if (len1 <= 0 || memchr(out, '\0', out_size) == NULL) {
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memset(out, 0, out_size);
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return false;
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}
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return true; // Obtained the symbol name.
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}
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}
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i += num_symbols_in_buf;
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}
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return false;
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}
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// Get the symbol name of "pc" from the file pointed by "fd". Process
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// both regular and dynamic symbol tables if necessary. On success,
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// write the symbol name to "out" and return true. Otherwise, return
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// false.
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static bool GetSymbolFromObjectFile(const int fd,
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uint64_t pc,
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char* out,
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int out_size,
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uint64_t base_address) {
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// Read the ELF header.
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ElfW(Ehdr) elf_header;
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if (!ReadFromOffsetExact(fd, &elf_header, sizeof(elf_header), 0)) {
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return false;
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}
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ElfW(Shdr) symtab, strtab;
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// Consult a regular symbol table first.
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if (GetSectionHeaderByType(fd, elf_header.e_shnum, elf_header.e_shoff,
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SHT_SYMTAB, &symtab)) {
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if (!ReadFromOffsetExact(fd, &strtab, sizeof(strtab), elf_header.e_shoff +
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symtab.sh_link * sizeof(symtab))) {
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return false;
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}
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if (FindSymbol(pc, fd, out, out_size, base_address, &strtab, &symtab)) {
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return true; // Found the symbol in a regular symbol table.
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}
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}
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// If the symbol is not found, then consult a dynamic symbol table.
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if (GetSectionHeaderByType(fd, elf_header.e_shnum, elf_header.e_shoff,
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SHT_DYNSYM, &symtab)) {
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if (!ReadFromOffsetExact(fd, &strtab, sizeof(strtab), elf_header.e_shoff +
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symtab.sh_link * sizeof(symtab))) {
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return false;
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}
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if (FindSymbol(pc, fd, out, out_size, base_address, &strtab, &symtab)) {
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return true; // Found the symbol in a dynamic symbol table.
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}
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}
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return false;
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}
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namespace {
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// Thin wrapper around a file descriptor so that the file descriptor
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// gets closed for sure.
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struct FileDescriptor {
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const int fd_;
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explicit FileDescriptor(int fd) : fd_(fd) {}
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~FileDescriptor() {
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if (fd_ >= 0) {
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close(fd_);
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}
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}
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int get() { return fd_; }
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private:
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explicit FileDescriptor(const FileDescriptor&);
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void operator=(const FileDescriptor&);
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};
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// Helper class for reading lines from file.
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//
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// Note: we don't use ProcMapsIterator since the object is big (it has
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// a 5k array member) and uses async-unsafe functions such as sscanf()
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// and snprintf().
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class LineReader {
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public:
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explicit LineReader(int fd, char *buf, int buf_len, off_t offset)
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: fd_(fd),
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buf_(buf),
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buf_len_(buf_len),
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offset_(offset),
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bol_(buf),
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eol_(buf),
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eod_(buf) {}
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// Read '\n'-terminated line from file. On success, modify "bol"
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// and "eol", then return true. Otherwise, return false.
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//
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// Note: if the last line doesn't end with '\n', the line will be
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// dropped. It's an intentional behavior to make the code simple.
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bool ReadLine(const char **bol, const char **eol) {
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if (BufferIsEmpty()) { // First time.
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const ssize_t num_bytes = ReadFromOffset(fd_, buf_, buf_len_, offset_);
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if (num_bytes <= 0) { // EOF or error.
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return false;
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}
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offset_ += num_bytes;
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eod_ = buf_ + num_bytes;
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bol_ = buf_;
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} else {
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bol_ = eol_ + 1; // Advance to the next line in the buffer.
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SAFE_ASSERT(bol_ <= eod_); // "bol_" can point to "eod_".
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if (!HasCompleteLine()) {
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const int incomplete_line_length = eod_ - bol_;
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// Move the trailing incomplete line to the beginning.
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memmove(buf_, bol_, incomplete_line_length);
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// Read text from file and append it.
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char * const append_pos = buf_ + incomplete_line_length;
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const int capacity_left = buf_len_ - incomplete_line_length;
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const ssize_t num_bytes =
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ReadFromOffset(fd_, append_pos, capacity_left, offset_);
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if (num_bytes <= 0) { // EOF or error.
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return false;
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}
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offset_ += num_bytes;
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eod_ = append_pos + num_bytes;
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bol_ = buf_;
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}
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}
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eol_ = FindLineFeed();
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if (eol_ == NULL) { // '\n' not found. Malformed line.
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return false;
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}
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*eol_ = '\0'; // Replace '\n' with '\0'.
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*bol = bol_;
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*eol = eol_;
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return true;
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}
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// Beginning of line.
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const char *bol() {
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return bol_;
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}
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// End of line.
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const char *eol() {
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return eol_;
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}
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private:
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explicit LineReader(const LineReader&);
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void operator=(const LineReader&);
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char *FindLineFeed() {
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return reinterpret_cast<char *>(memchr(bol_, '\n', eod_ - bol_));
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}
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bool BufferIsEmpty() {
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return buf_ == eod_;
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}
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bool HasCompleteLine() {
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return !BufferIsEmpty() && FindLineFeed() != NULL;
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}
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const int fd_;
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char * const buf_;
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const int buf_len_;
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off_t offset_;
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char *bol_;
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char *eol_;
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const char *eod_; // End of data in "buf_".
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|
};
|
|
} // namespace
|
|
|
|
// Place the hex number read from "start" into "*hex". The pointer to
|
|
// the first non-hex character or "end" is returned.
|
|
static char *GetHex(const char *start, const char *end, uint64_t *hex) {
|
|
*hex = 0;
|
|
const char *p;
|
|
for (p = start; p < end; ++p) {
|
|
int ch = *p;
|
|
if ((ch >= '0' && ch <= '9') ||
|
|
(ch >= 'A' && ch <= 'F') || (ch >= 'a' && ch <= 'f')) {
|
|
*hex = (*hex << 4) | (ch < 'A' ? ch - '0' : (ch & 0xF) + 9);
|
|
} else { // Encountered the first non-hex character.
|
|
break;
|
|
}
|
|
}
|
|
SAFE_ASSERT(p <= end);
|
|
return const_cast<char *>(p);
|
|
}
|
|
|
|
// Searches for the object file (from /proc/self/maps) that contains
|
|
// the specified pc. If found, sets |start_address| to the start address
|
|
// of where this object file is mapped in memory, sets the module base
|
|
// address into |base_address|, copies the object file name into
|
|
// |out_file_name|, and attempts to open the object file. If the object
|
|
// file is opened successfully, returns the file descriptor. Otherwise,
|
|
// returns -1. |out_file_name_size| is the size of the file name buffer
|
|
// (including the null-terminator).
|
|
static ATTRIBUTE_NOINLINE int
|
|
OpenObjectFileContainingPcAndGetStartAddress(uint64_t pc,
|
|
uint64_t &start_address,
|
|
uint64_t &base_address,
|
|
char *out_file_name,
|
|
int out_file_name_size) {
|
|
int object_fd;
|
|
|
|
int maps_fd;
|
|
NO_INTR(maps_fd = open("/proc/self/maps", O_RDONLY));
|
|
FileDescriptor wrapped_maps_fd(maps_fd);
|
|
if (wrapped_maps_fd.get() < 0) {
|
|
return -1;
|
|
}
|
|
|
|
int mem_fd;
|
|
NO_INTR(mem_fd = open("/proc/self/mem", O_RDONLY));
|
|
FileDescriptor wrapped_mem_fd(mem_fd);
|
|
if (wrapped_mem_fd.get() < 0) {
|
|
return -1;
|
|
}
|
|
|
|
// Iterate over maps and look for the map containing the pc. Then
|
|
// look into the symbol tables inside.
|
|
char buf[1024]; // Big enough for line of sane /proc/self/maps
|
|
int num_maps = 0;
|
|
LineReader reader(wrapped_maps_fd.get(), buf, sizeof(buf), 0);
|
|
while (true) {
|
|
num_maps++;
|
|
const char *cursor;
|
|
const char *eol;
|
|
if (!reader.ReadLine(&cursor, &eol)) { // EOF or malformed line.
|
|
return -1;
|
|
}
|
|
|
|
// Start parsing line in /proc/self/maps. Here is an example:
|
|
//
|
|
// 08048000-0804c000 r-xp 00000000 08:01 2142121 /bin/cat
|
|
//
|
|
// We want start address (08048000), end address (0804c000), flags
|
|
// (r-xp) and file name (/bin/cat).
|
|
|
|
// Read start address.
|
|
cursor = GetHex(cursor, eol, &start_address);
|
|
if (cursor == eol || *cursor != '-') {
|
|
return -1; // Malformed line.
|
|
}
|
|
++cursor; // Skip '-'.
|
|
|
|
// Read end address.
|
|
uint64_t end_address;
|
|
cursor = GetHex(cursor, eol, &end_address);
|
|
if (cursor == eol || *cursor != ' ') {
|
|
return -1; // Malformed line.
|
|
}
|
|
++cursor; // Skip ' '.
|
|
|
|
// Read flags. Skip flags until we encounter a space or eol.
|
|
const char * const flags_start = cursor;
|
|
while (cursor < eol && *cursor != ' ') {
|
|
++cursor;
|
|
}
|
|
// We expect at least four letters for flags (ex. "r-xp").
|
|
if (cursor == eol || cursor < flags_start + 4) {
|
|
return -1; // Malformed line.
|
|
}
|
|
|
|
// Determine the base address by reading ELF headers in process memory.
|
|
ElfW(Ehdr) ehdr;
|
|
// Skip non-readable maps.
|
|
if (flags_start[0] == 'r' &&
|
|
ReadFromOffsetExact(mem_fd, &ehdr, sizeof(ElfW(Ehdr)), start_address) &&
|
|
memcmp(ehdr.e_ident, ELFMAG, SELFMAG) == 0) {
|
|
switch (ehdr.e_type) {
|
|
case ET_EXEC:
|
|
base_address = 0;
|
|
break;
|
|
case ET_DYN:
|
|
// Find the segment containing file offset 0. This will correspond
|
|
// to the ELF header that we just read. Normally this will have
|
|
// virtual address 0, but this is not guaranteed. We must subtract
|
|
// the virtual address from the address where the ELF header was
|
|
// mapped to get the base address.
|
|
//
|
|
// If we fail to find a segment for file offset 0, use the address
|
|
// of the ELF header as the base address.
|
|
base_address = start_address;
|
|
for (unsigned i = 0; i != ehdr.e_phnum; ++i) {
|
|
ElfW(Phdr) phdr;
|
|
if (ReadFromOffsetExact(
|
|
mem_fd, &phdr, sizeof(phdr),
|
|
start_address + ehdr.e_phoff + i * sizeof(phdr)) &&
|
|
phdr.p_type == PT_LOAD && phdr.p_offset == 0) {
|
|
base_address = start_address - phdr.p_vaddr;
|
|
break;
|
|
}
|
|
}
|
|
break;
|
|
default:
|
|
// ET_REL or ET_CORE. These aren't directly executable, so they don't
|
|
// affect the base address.
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Check start and end addresses.
|
|
if (!(start_address <= pc && pc < end_address)) {
|
|
continue; // We skip this map. PC isn't in this map.
|
|
}
|
|
|
|
// Check flags. We are only interested in "r*x" maps.
|
|
if (flags_start[0] != 'r' || flags_start[2] != 'x') {
|
|
continue; // We skip this map.
|
|
}
|
|
++cursor; // Skip ' '.
|
|
|
|
// Read file offset.
|
|
uint64_t file_offset;
|
|
cursor = GetHex(cursor, eol, &file_offset);
|
|
if (cursor == eol || *cursor != ' ') {
|
|
return -1; // Malformed line.
|
|
}
|
|
++cursor; // Skip ' '.
|
|
|
|
// Skip to file name. "cursor" now points to dev. We need to
|
|
// skip at least two spaces for dev and inode.
|
|
int num_spaces = 0;
|
|
while (cursor < eol) {
|
|
if (*cursor == ' ') {
|
|
++num_spaces;
|
|
} else if (num_spaces >= 2) {
|
|
// The first non-space character after skipping two spaces
|
|
// is the beginning of the file name.
|
|
break;
|
|
}
|
|
++cursor;
|
|
}
|
|
if (cursor == eol) {
|
|
return -1; // Malformed line.
|
|
}
|
|
|
|
// Finally, "cursor" now points to file name of our interest.
|
|
NO_INTR(object_fd = open(cursor, O_RDONLY));
|
|
if (object_fd < 0) {
|
|
// Failed to open object file. Copy the object file name to
|
|
// |out_file_name|.
|
|
strncpy(out_file_name, cursor, out_file_name_size);
|
|
// Making sure |out_file_name| is always null-terminated.
|
|
out_file_name[out_file_name_size - 1] = '\0';
|
|
return -1;
|
|
}
|
|
return object_fd;
|
|
}
|
|
}
|
|
|
|
// POSIX doesn't define any async-signal safe function for converting
|
|
// an integer to ASCII. We'll have to define our own version.
|
|
// itoa_r() converts a (signed) integer to ASCII. It returns "buf", if the
|
|
// conversion was successful or NULL otherwise. It never writes more than "sz"
|
|
// bytes. Output will be truncated as needed, and a NUL character is always
|
|
// appended.
|
|
// NOTE: code from sandbox/linux/seccomp-bpf/demo.cc.
|
|
static char *itoa_r(intptr_t i, char *buf, size_t sz, int base, size_t padding) {
|
|
// Make sure we can write at least one NUL byte.
|
|
size_t n = 1;
|
|
if (n > sz)
|
|
return NULL;
|
|
|
|
if (base < 2 || base > 16) {
|
|
buf[0] = '\000';
|
|
return NULL;
|
|
}
|
|
|
|
char *start = buf;
|
|
|
|
uintptr_t j = i;
|
|
|
|
// Handle negative numbers (only for base 10).
|
|
if (i < 0 && base == 10) {
|
|
// This does "j = -i" while avoiding integer overflow.
|
|
j = static_cast<uintptr_t>(-(i + 1)) + 1;
|
|
|
|
// Make sure we can write the '-' character.
|
|
if (++n > sz) {
|
|
buf[0] = '\000';
|
|
return NULL;
|
|
}
|
|
*start++ = '-';
|
|
}
|
|
|
|
// Loop until we have converted the entire number. Output at least one
|
|
// character (i.e. '0').
|
|
char *ptr = start;
|
|
do {
|
|
// Make sure there is still enough space left in our output buffer.
|
|
if (++n > sz) {
|
|
buf[0] = '\000';
|
|
return NULL;
|
|
}
|
|
|
|
// Output the next digit.
|
|
*ptr++ = "0123456789abcdef"[j % base];
|
|
j /= base;
|
|
|
|
if (padding > 0)
|
|
padding--;
|
|
} while (j > 0 || padding > 0);
|
|
|
|
// Terminate the output with a NUL character.
|
|
*ptr = '\000';
|
|
|
|
// Conversion to ASCII actually resulted in the digits being in reverse
|
|
// order. We can't easily generate them in forward order, as we can't tell
|
|
// the number of characters needed until we are done converting.
|
|
// So, now, we reverse the string (except for the possible "-" sign).
|
|
while (--ptr > start) {
|
|
char ch = *ptr;
|
|
*ptr = *start;
|
|
*start++ = ch;
|
|
}
|
|
return buf;
|
|
}
|
|
|
|
// Safely appends string |source| to string |dest|. Never writes past the
|
|
// buffer size |dest_size| and guarantees that |dest| is null-terminated.
|
|
static void SafeAppendString(const char* source, char* dest, int dest_size) {
|
|
int dest_string_length = strlen(dest);
|
|
SAFE_ASSERT(dest_string_length < dest_size);
|
|
dest += dest_string_length;
|
|
dest_size -= dest_string_length;
|
|
strncpy(dest, source, dest_size);
|
|
// Making sure |dest| is always null-terminated.
|
|
dest[dest_size - 1] = '\0';
|
|
}
|
|
|
|
// Converts a 64-bit value into a hex string, and safely appends it to |dest|.
|
|
// Never writes past the buffer size |dest_size| and guarantees that |dest| is
|
|
// null-terminated.
|
|
static void SafeAppendHexNumber(uint64_t value, char* dest, int dest_size) {
|
|
// 64-bit numbers in hex can have up to 16 digits.
|
|
char buf[17] = {'\0'};
|
|
SafeAppendString(itoa_r(value, buf, sizeof(buf), 16, 0), dest, dest_size);
|
|
}
|
|
|
|
// The implementation of our symbolization routine. If it
|
|
// successfully finds the symbol containing "pc" and obtains the
|
|
// symbol name, returns true and write the symbol name to "out".
|
|
// Otherwise, returns false. If Callback function is installed via
|
|
// InstallSymbolizeCallback(), the function is also called in this function,
|
|
// and "out" is used as its output.
|
|
// To keep stack consumption low, we would like this function to not
|
|
// get inlined.
|
|
static ATTRIBUTE_NOINLINE bool SymbolizeAndDemangle(void *pc, char *out,
|
|
int out_size) {
|
|
uint64_t pc0 = reinterpret_cast<uintptr_t>(pc);
|
|
uint64_t start_address = 0;
|
|
uint64_t base_address = 0;
|
|
int object_fd = -1;
|
|
|
|
if (out_size < 1) {
|
|
return false;
|
|
}
|
|
out[0] = '\0';
|
|
SafeAppendString("(", out, out_size);
|
|
|
|
if (g_symbolize_open_object_file_callback) {
|
|
object_fd = g_symbolize_open_object_file_callback(pc0, start_address,
|
|
base_address, out + 1,
|
|
out_size - 1);
|
|
} else {
|
|
object_fd = OpenObjectFileContainingPcAndGetStartAddress(pc0, start_address,
|
|
base_address,
|
|
out + 1,
|
|
out_size - 1);
|
|
}
|
|
|
|
FileDescriptor wrapped_object_fd(object_fd);
|
|
|
|
#if defined(PRINT_UNSYMBOLIZED_STACK_TRACES)
|
|
{
|
|
#else
|
|
// Check whether a file name was returned.
|
|
if (object_fd < 0) {
|
|
#endif
|
|
if (out[1]) {
|
|
// The object file containing PC was determined successfully however the
|
|
// object file was not opened successfully. This is still considered
|
|
// success because the object file name and offset are known and tools
|
|
// like asan_symbolize.py can be used for the symbolization.
|
|
out[out_size - 1] = '\0'; // Making sure |out| is always null-terminated.
|
|
SafeAppendString("+0x", out, out_size);
|
|
SafeAppendHexNumber(pc0 - base_address, out, out_size);
|
|
SafeAppendString(")", out, out_size);
|
|
return true;
|
|
}
|
|
// Failed to determine the object file containing PC. Bail out.
|
|
return false;
|
|
}
|
|
int elf_type = FileGetElfType(wrapped_object_fd.get());
|
|
if (elf_type == -1) {
|
|
return false;
|
|
}
|
|
if (g_symbolize_callback) {
|
|
// Run the call back if it's installed.
|
|
// Note: relocation (and much of the rest of this code) will be
|
|
// wrong for prelinked shared libraries and PIE executables.
|
|
uint64_t relocation = (elf_type == ET_DYN) ? start_address : 0;
|
|
int num_bytes_written = g_symbolize_callback(wrapped_object_fd.get(),
|
|
pc, out, out_size,
|
|
relocation);
|
|
if (num_bytes_written > 0) {
|
|
out += num_bytes_written;
|
|
out_size -= num_bytes_written;
|
|
}
|
|
}
|
|
if (!GetSymbolFromObjectFile(wrapped_object_fd.get(), pc0,
|
|
out, out_size, base_address)) {
|
|
if (out[1] && !g_symbolize_callback) {
|
|
// The object file containing PC was opened successfully however the
|
|
// symbol was not found. The object may have been stripped. This is still
|
|
// considered success because the object file name and offset are known
|
|
// and tools like asan_symbolize.py can be used for the symbolization.
|
|
out[out_size - 1] = '\0'; // Making sure |out| is always null-terminated.
|
|
SafeAppendString("+0x", out, out_size);
|
|
SafeAppendHexNumber(pc0 - base_address, out, out_size);
|
|
SafeAppendString(")", out, out_size);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// Symbolization succeeded. Now we try to demangle the symbol.
|
|
DemangleInplace(out, out_size);
|
|
return true;
|
|
}
|
|
|
|
_END_GOOGLE_NAMESPACE_
|
|
|
|
#elif defined(OS_MACOSX) && defined(HAVE_DLADDR)
|
|
|
|
#include <dlfcn.h>
|
|
#include <string.h>
|
|
|
|
_START_GOOGLE_NAMESPACE_
|
|
|
|
static ATTRIBUTE_NOINLINE bool SymbolizeAndDemangle(void *pc, char *out,
|
|
int out_size) {
|
|
Dl_info info;
|
|
if (dladdr(pc, &info)) {
|
|
if ((int)strlen(info.dli_sname) < out_size) {
|
|
strcpy(out, info.dli_sname);
|
|
// Symbolization succeeded. Now we try to demangle the symbol.
|
|
DemangleInplace(out, out_size);
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
_END_GOOGLE_NAMESPACE_
|
|
|
|
#elif defined(OS_WINDOWS) || defined(OS_CYGWIN)
|
|
|
|
#include <windows.h>
|
|
#include <dbghelp.h>
|
|
|
|
#ifdef _MSC_VER
|
|
#pragma comment(lib, "dbghelp")
|
|
#endif
|
|
|
|
_START_GOOGLE_NAMESPACE_
|
|
|
|
class SymInitializer {
|
|
public:
|
|
HANDLE process;
|
|
bool ready;
|
|
SymInitializer() : process(NULL), ready(false) {
|
|
// Initialize the symbol handler.
|
|
// https://msdn.microsoft.com/en-us/library/windows/desktop/ms680344(v=vs.85).aspx
|
|
process = GetCurrentProcess();
|
|
// Defer symbol loading.
|
|
// We do not request undecorated symbols with SYMOPT_UNDNAME
|
|
// because the mangling library calls UnDecorateSymbolName.
|
|
SymSetOptions(SYMOPT_DEFERRED_LOADS);
|
|
if (SymInitialize(process, NULL, true)) {
|
|
ready = true;
|
|
}
|
|
}
|
|
~SymInitializer() {
|
|
SymCleanup(process);
|
|
// We do not need to close `HANDLE process` because it's a "pseudo handle."
|
|
}
|
|
private:
|
|
SymInitializer(const SymInitializer&);
|
|
SymInitializer& operator=(const SymInitializer&);
|
|
};
|
|
|
|
static ATTRIBUTE_NOINLINE bool SymbolizeAndDemangle(void *pc, char *out,
|
|
int out_size) {
|
|
const static SymInitializer symInitializer;
|
|
if (!symInitializer.ready) {
|
|
return false;
|
|
}
|
|
// Resolve symbol information from address.
|
|
// https://msdn.microsoft.com/en-us/library/windows/desktop/ms680578(v=vs.85).aspx
|
|
char buf[sizeof(SYMBOL_INFO) + MAX_SYM_NAME];
|
|
SYMBOL_INFO *symbol = reinterpret_cast<SYMBOL_INFO *>(buf);
|
|
symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
|
|
symbol->MaxNameLen = MAX_SYM_NAME;
|
|
// We use the ANSI version to ensure the string type is always `char *`.
|
|
// This could break if a symbol has Unicode in it.
|
|
BOOL ret = SymFromAddr(symInitializer.process,
|
|
reinterpret_cast<DWORD64>(pc), 0, symbol);
|
|
if (ret == 1 && static_cast<int>(symbol->NameLen) < out_size) {
|
|
// `NameLen` does not include the null terminating character.
|
|
strncpy(out, symbol->Name, static_cast<size_t>(symbol->NameLen) + 1);
|
|
out[static_cast<size_t>(symbol->NameLen)] = '\0';
|
|
// Symbolization succeeded. Now we try to demangle the symbol.
|
|
DemangleInplace(out, out_size);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
_END_GOOGLE_NAMESPACE_
|
|
|
|
#else
|
|
# error BUG: HAVE_SYMBOLIZE was wrongly set
|
|
#endif
|
|
|
|
_START_GOOGLE_NAMESPACE_
|
|
|
|
bool Symbolize(void *pc, char *out, int out_size) {
|
|
SAFE_ASSERT(out_size >= 0);
|
|
return SymbolizeAndDemangle(pc, out, out_size);
|
|
}
|
|
|
|
_END_GOOGLE_NAMESPACE_
|
|
|
|
#else /* HAVE_SYMBOLIZE */
|
|
|
|
#include <assert.h>
|
|
|
|
#include "config.h"
|
|
|
|
_START_GOOGLE_NAMESPACE_
|
|
|
|
// TODO: Support other environments.
|
|
bool Symbolize(void *pc, char *out, int out_size) {
|
|
assert(0);
|
|
return false;
|
|
}
|
|
|
|
_END_GOOGLE_NAMESPACE_
|
|
|
|
#endif
|