Skip library frames when unwinding

CMakeLists.txt

@@ -12,7 +12,7 @@ project(
 
 set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON)
 
-#set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 
 include(GNUInstallDirs)
 include(CheckCXXSourceCompiles)
@@ -63,6 +63,7 @@ option(LIBCPPTRACE_DEMANGLE_WITH_CXXABI "" OFF)
 option(LIBCPPTRACE_DEMANGLE_WITH_NOTHING "" OFF)
 
 set(LIBCPP_BACKTRACE_PATH "" CACHE STRING "Path to backtrace.h, if the compiler doesn't already know it. Check /usr/lib/gcc/x86_64-linux-gnu/*/include.")
+set(LIBCPPTRACE_HARD_MAX_FRAMES "" CACHE STRING "Hard limit on unwinding depth. Default is 100.")
 
 if(NOT "${LIBCPP_BACKTRACE_PATH}" STREQUAL "")
   # quotes used over <> because of a macro substitution issue where
@@ -254,6 +255,10 @@ if(NOT "${LIBCPP_BACKTRACE_PATH}" STREQUAL "")
   target_compile_definitions(cpptrace PUBLIC LIBCPP_BACKTRACE_PATH=${LIBCPP_BACKTRACE_PATH})
 endif()
 
+if(NOT "${LIBCPPTRACE_HARD_MAX_FRAMES}" STREQUAL "")
+  target_compile_definitions(cpptrace PUBLIC LIBCPPTRACE_HARD_MAX_FRAMES=${LIBCPPTRACE_HARD_MAX_FRAMES})
+endif()
+
 # ======================================================================================================================
 
 #target_link_libraries(

README.md

@@ -57,6 +57,9 @@ also manually set which back-end you want used.
 | winapi | `LIBCPPTRACE_UNWIND_WITH_WINAPI` | ✔️ | ❌ | Frames are captured with `CaptureStackBackTrace`. |
 | N/A | `LIBCPPTRACE_UNWIND_WITH_NOTHING` | ✔️ | ✔️ | Unwinding is not done, stack traces will be empty. |
 
+Some back-ends require a fixed buffer has to be created to read addresses into while unwinding. By default the buffer
+can hold addresses for 100 frames. This is configurable with `LIBCPPTRACE_HARD_MAX_FRAMES`.
+
 **Symbol resolution**
 
 | Library | CMake config | Windows | Linux | Info |
@@ -80,7 +83,8 @@ mangled.
 **Full tracing**
 
 Libbacktrace can generate a full stack trace itself, both unwinding and resolving symbols. This can be chosen with
-`LIBCPPTRACE_FULL_TRACE_WITH_LIBBACKTRACE`. This is also the first configuration the auto config attempts to use.
+`LIBCPPTRACE_FULL_TRACE_WITH_LIBBACKTRACE`. This is also the first configuration the auto config attempts to use. Full
+tracing with libbacktrace ignores `LIBCPPTRACE_HARD_MAX_FRAMES`.
 
 There are plenty more libraries that can be used for unwinding, parsing debug information, and demangling. In the future
 more back-ends can be added. Ideally this library can "just work" on systems, without additional installation work.

src/cpptrace.cpp

@@ -10,10 +10,12 @@
 #include "symbols/libcpp_symbols.hpp"
 #include "unwind/libcpp_unwind.hpp"
 #include "demangle/libcpp_demangle.hpp"
+#include "platform/libcpp_common.hpp"
 
 namespace cpptrace {
+    LIBCPPTRACE_FORCE_NO_INLINE
     std::vector<stacktrace_frame> generate_trace() {
-        std::vector<void*> frames = detail::capture_frames();
+        std::vector<void*> frames = detail::capture_frames(1);
         std::vector<stacktrace_frame> trace;
         detail::symbolizer symbolizer;
         for(const auto frame : frames) {
@@ -33,8 +35,9 @@ namespace cpptrace {
 #include "demangle/libcpp_demangle.hpp"
 
 namespace cpptrace {
+    LIBCPPTRACE_FORCE_NO_INLINE
     std::vector<stacktrace_frame> generate_trace() {
-        auto trace = detail::generate_trace();
+        auto trace = detail::generate_trace(1);
         for(auto& entry : trace) {
             entry.symbol = detail::demangle(entry.symbol);
         }
@@ -48,12 +51,15 @@ namespace cpptrace {
     void print_trace() {
         std::cerr<<"Stack trace (most recent call first):"<<std::endl;
         std::size_t i = 0;
-        for(const auto& frame : generate_trace()) {
+        const auto trace = generate_trace();
+        // +1 to skip one frame
+        for(auto it = trace.begin() + 1; it != trace.end(); it++) {
+            const auto& frame = *it;
             std::cerr
                 << i++
                 << " "
                 << frame.filename
-                << " at "
+                << ":"
                 << frame.line
                 << (frame.col > 0 ? ":" + std::to_string(frame.col) : "")
                 << " "

src/full/full_trace_with_libbacktrace.cpp

@@ -3,6 +3,7 @@
 #include <cpptrace/cpptrace.hpp>
 #include "libcpp_full_trace.hpp"
 #include "../platform/libcpp_program_name.hpp"
+#include "../platform/libcpp_common.hpp"
 
 #include <vector>
 
@@ -14,14 +15,24 @@
 
 namespace cpptrace {
     namespace detail {
-        int full_callback(void* data, uintptr_t address, const char* file, int line, const char* symbol) {
+        struct trace_data {
-            reinterpret_cast<std::vector<stacktrace_frame>*>(data)->push_back({
+            std::vector<stacktrace_frame>& frames;
-                address,
+            size_t& skip;
-                line,
+        };
-                -1,
+
-                file ? file : "",
+        int full_callback(void* data_pointer, uintptr_t address, const char* file, int line, const char* symbol) {
-                symbol ? symbol : ""
+            trace_data& data = *reinterpret_cast<trace_data*>(data_pointer);
-            });
+            if(data.skip > 0) {
+                data.skip--;
+            } else {
+                data.frames.push_back({
+                    address,
+                    line,
+                    -1,
+                    file ? file : "",
+                    symbol ? symbol : ""
+                });
+            }
             return 0;
         }
 
@@ -40,9 +51,12 @@ namespace cpptrace {
             return state;
         }
 
-        std::vector<stacktrace_frame> generate_trace() {
+        LIBCPPTRACE_FORCE_NO_INLINE
+        std::vector<stacktrace_frame> generate_trace(size_t skip) {
             std::vector<stacktrace_frame> frames;
-            backtrace_full(get_backtrace_state(), 0, full_callback, error_callback, &frames);
+            skip++; // add one for this call
+            trace_data data { frames, skip };
+            backtrace_full(get_backtrace_state(), 0, full_callback, error_callback, &data);
             return frames;
         }
     }

src/full/libcpp_full_trace.hpp

@@ -2,12 +2,15 @@
 #define LIBCPP_FULL_TRACE_HPP
 
 #include <cpptrace/cpptrace.hpp>
+#include "../platform/libcpp_common.hpp"
 
+#include <cstddef>
 #include <vector>
 
 namespace cpptrace {
     namespace detail {
-        std::vector<stacktrace_frame> generate_trace();
+        LIBCPPTRACE_FORCE_NO_INLINE
+        std::vector<stacktrace_frame> generate_trace(size_t skip);
     }
 }
 

src/platform/libcpp_common.hpp

@@ -0,0 +1,10 @@
+#ifndef LIBCPP_COMMON_HPP
+#define LIBCPP_COMMON_HPP
+
+#ifdef _MSC_VER
+#define LIBCPPTRACE_FORCE_NO_INLINE __declspec(noinline)
+#else
+#define LIBCPPTRACE_FORCE_NO_INLINE __attribute__((noinline))
+#endif
+
+#endif

src/unwind/libcpp_unwind.hpp

@@ -2,6 +2,7 @@
 #define LIBCPP_UNWIND_HPP
 
 #include <cpptrace/cpptrace.hpp>
+#include "../platform/libcpp_common.hpp"
 
 #include <cstddef>
 
@@ -12,7 +13,8 @@ namespace cpptrace {
         #else
         constexpr size_t hard_max_frames = 100;
         #endif
-        std::vector<void*> capture_frames();
+        LIBCPPTRACE_FORCE_NO_INLINE
+        std::vector<void*> capture_frames(size_t skip);
     }
 }
 

src/unwind/unwind_with_execinfo.cpp

@@ -2,17 +2,21 @@
 
 #include <cpptrace/cpptrace.hpp>
 #include "libcpp_unwind.hpp"
+#include "../platform/libcpp_common.hpp"
 
+#include <algorithm>
 #include <vector>
 
 #include <execinfo.h>
 
 namespace cpptrace {
     namespace detail {
-        std::vector<void*> capture_frames() {
+        LIBCPPTRACE_FORCE_NO_INLINE
-            std::vector<void*> frames(hard_max_frames, nullptr);
+        std::vector<void*> capture_frames(size_t skip) {
-            int n_frames = backtrace(frames.data(), hard_max_frames);
+            std::vector<void*> frames(hard_max_frames + skip, nullptr);
+            int n_frames = backtrace(frames.data(), hard_max_frames + skip);
             frames.resize(n_frames);
+            frames.erase(frames.begin(), frames.begin() + std::min(skip + 1, frames.size()));
             frames.shrink_to_fit();
             return frames;
         }

src/unwind/unwind_with_nothing.cpp

@@ -7,7 +7,7 @@
 
 namespace cpptrace {
     namespace detail {
-        std::vector<void*> capture_frames() {
+        std::vector<void*> capture_frames(size_t) {
             return {};
         }
     }

src/unwind/unwind_with_winapi.cpp

@@ -2,6 +2,7 @@
 
 #include <cpptrace/cpptrace.hpp>
 #include "libcpp_unwind.hpp"
+#include "../platform/libcpp_common.hpp"
 
 #include <vector>
 
@@ -9,9 +10,10 @@
 
 namespace cpptrace {
     namespace detail {
-        std::vector<void*> capture_frames() {
+        LIBCPPTRACE_FORCE_NO_INLINE
+        std::vector<void*> capture_frames(size_t skip) {
             std::vector<PVOID> addrs(hard_max_frames, nullptr);
-            int frames = CaptureStackBackTrace(0, hard_max_frames, addrs.data(), NULL);
+            int frames = CaptureStackBackTrace(static_cast<DWORD>(skip + 1), hard_max_frames, addrs.data(), NULL);
             addrs.resize(frames);
             addrs.shrink_to_fit();
             return addrs;