1 //===-- backtrace_linux_libc.cpp --------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include <assert.h>
10 #include <execinfo.h>
11 #include <stddef.h>
12 #include <stdint.h>
13 #include <stdlib.h>
14 #include <string.h>
15 
16 #include "gwp_asan/definitions.h"
17 #include "gwp_asan/optional/backtrace.h"
18 #include "gwp_asan/optional/printf.h"
19 #include "gwp_asan/options.h"
20 
21 namespace {
22 size_t Backtrace(uintptr_t *TraceBuffer, size_t Size) {
23   static_assert(sizeof(uintptr_t) == sizeof(void *), "uintptr_t is not void*");
24 
25   return backtrace(reinterpret_cast<void **>(TraceBuffer), Size);
26 }
27 
28 // We don't need any custom handling for the Segv backtrace - the libc unwinder
29 // has no problems with unwinding through a signal handler. Force inlining here
30 // to avoid the additional frame.
31 GWP_ASAN_ALWAYS_INLINE size_t SegvBacktrace(uintptr_t *TraceBuffer, size_t Size,
32                                             void * /*Context*/) {
33   return Backtrace(TraceBuffer, Size);
34 }
35 
36 static void PrintBacktrace(uintptr_t *Trace, size_t TraceLength,
37                            gwp_asan::Printf_t Printf) {
38   if (TraceLength == 0) {
39     Printf("  <not found (does your allocator support backtracing?)>\n\n");
40     return;
41   }
42 
43   char **BacktraceSymbols =
44       backtrace_symbols(reinterpret_cast<void **>(Trace), TraceLength);
45 
46   for (size_t i = 0; i < TraceLength; ++i) {
47     if (!BacktraceSymbols)
48       Printf("  #%zu %p\n", i, Trace[i]);
49     else
50       Printf("  #%zu %s\n", i, BacktraceSymbols[i]);
51   }
52 
53   Printf("\n");
54   if (BacktraceSymbols)
55     free(BacktraceSymbols);
56 }
57 } // anonymous namespace
58 
59 namespace gwp_asan {
60 namespace backtrace {
61 
62 options::Backtrace_t getBacktraceFunction() { return Backtrace; }
63 PrintBacktrace_t getPrintBacktraceFunction() { return PrintBacktrace; }
64 SegvBacktrace_t getSegvBacktraceFunction() { return SegvBacktrace; }
65 
66 } // namespace backtrace
67 } // namespace gwp_asan
68