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/* SPDX-License-Identifier: GPL-3.0-or-later
* Copyright © 2020 The TokTok team.
*/
#include <sys/param.h>
#include <unistd.h>
#include <algorithm>
#include <array>
#include <cassert>
#include <cstdio>
#include <cstring>
#include <map>
#include <memory>
#include <string>
#define LOG_TO_STDOUT 0
/**
* This file contains the support code for using -finstrument-functions.
*
* If you link this into a program, e.g. a test program, that was compiled with
* -finstrument-functions, it will print an indented execution trace. E.g.:
*
* @code
* int g() { return 0; }
* int f() { return g(); }
* int main() { return f(); }
* @endcode
*
* Compiling the above with instrumentation and linking it with this file will
* result in the following output:
*
* @verbatim
* -> main
* -> f
* -> g
* <- g
* <- f
* <- main
* @endverbatim
*
* There are a few filter options you can apply below. Note that you'll need
* addr2line in your PATH for this to work.
*/
namespace {
class CString {
char const *str_;
public:
// cppcheck-suppress noExplicitConstructor
constexpr CString(char const *str) : str_(str) {}
friend bool operator<(CString lhs, CString rhs) { return strcmp(lhs.str_, rhs.str_) < 0; }
};
template <std::size_t N>
bool contains(CString const (&array)[N], std::string const &str) {
return std::binary_search(array, array + N, str.c_str());
}
struct Symbol {
std::string const name;
std::string const file;
};
/**
* This array lists functions that should *not* appear in the trace.
*/
constexpr CString exclusions[] = {
"__bswap_32", "logger_callback_log", "make_family", "make_proto", "make_socktype",
};
/**
* This array lists source files that *should* appear in the trace.
*
* If this array is empty, all files are traced.
*/
constexpr CString filter_sources[] = {
"onion.c",
"onion_announce.c",
"onion_client.c",
};
class ExecutionTrace {
using Process = std::unique_ptr<FILE, decltype(&pclose)>;
using File = std::unique_ptr<FILE, decltype(&fclose)>;
std::string const exe = []() {
std::array<char, PATH_MAX> result;
ssize_t const count = readlink("/proc/self/exe", result.data(), result.size());
assert(count > 0);
return count > 0 ? std::string(result.data(), count) : "/proc/self/exe";
}();
#if LOG_TO_STDOUT
File const log_file{stdout, std::fclose};
#else
File const log_file{std::fopen("trace.log", "w"), std::fclose};
#endif
unsigned nesting = 0;
std::map<void *, Symbol> symbols;
static std::string sh(std::string cmd) {
std::string result;
Process pipe(popen(cmd.c_str(), "r"), pclose);
if (!pipe) {
return "<popen-failed>";
}
std::array<char, 128> buffer;
while (std::fgets(buffer.data(), buffer.size(), pipe.get()) != nullptr) {
result += buffer.data();
}
return result;
}
Symbol const &resolve(void *fn) {
// Already in the cache.
auto const found = symbols.find(fn);
if (found != symbols.end()) {
return found->second;
}
// 0x<64 bit number>\0
std::array<char, 16 + 3> addr;
std::snprintf(addr.data(), addr.size(), "0x%lx",
static_cast<unsigned long>(reinterpret_cast<uintptr_t>(fn)));
std::string const output = sh("addr2line -fs -e " + exe + " " + addr.data());
std::size_t const newline = output.find_first_of('\n');
std::size_t const colon = output.find_first_of(':');
std::string const sym = output.substr(0, newline);
std::string const file = output.substr(newline + 1, colon - (newline + 1));
auto const inserted = symbols.insert({fn, {sym, file}});
return inserted.first->second;
}
void indent() const {
for (unsigned i = 0; i < nesting; i++) {
std::fputc(' ', log_file.get());
}
}
void print(char const *prefix, Symbol const &sym) {
indent();
std::fprintf(log_file.get(), "%s %s (%s)\n", prefix, sym.name.c_str(), sym.file.c_str());
}
static bool excluded(Symbol const &sym) {
if (sizeof(filter_sources) != 0) {
if (!contains(filter_sources, sym.file)) {
return true;
}
}
return contains(exclusions, sym.name);
}
public:
void enter(void *fn) {
Symbol const &sym = resolve(fn);
if (!excluded(sym)) {
print("->", sym);
++nesting;
}
}
void exit(void *fn) {
Symbol const &sym = resolve(fn);
if (!excluded(sym)) {
--nesting;
print("<-", sym);
}
}
};
// We leak this one.
static ExecutionTrace *trace;
} // namespace
extern "C" void __cyg_profile_func_enter(void *this_fn, void *call_site)
__attribute__((__no_instrument_function__));
void __cyg_profile_func_enter(void *this_fn, void *call_site) {
if (trace == nullptr) {
trace = new ExecutionTrace();
}
trace->enter(this_fn);
}
extern "C" void __cyg_profile_func_exit(void *this_fn, void *call_site)
__attribute__((__no_instrument_function__));
void __cyg_profile_func_exit(void *this_fn, void *call_site) {
assert(trace != nullptr);
trace->exit(this_fn);
}
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