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StackTraceHandler: call the debugger directly, instead of via /bin/sh

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This removes one middle-man and a 512-byte variable in favor of a simple
32-bit enum. This was done in a way so we can extend to use either gdb
or lldb in any OS.

I've renamed the debuggerPresent() function to make its meaning clearer.

Pick-to: 6.3
Change-Id: I5ff8e16fcdcb4ffd9ab6fffd16eba561628ff89b
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Thiago Macieira 2022-05-03 09:32:06 -07:00
parent 4ea5e39b27
commit 9c0c1be122
1 changed files with 29 additions and 14 deletions
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43
src/testlib/qtestcase.cpp
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@ -109,8 +109,10 @@ using namespace Qt::StringLiterals;
using QtMiscUtils::toHexUpper;
using QtMiscUtils::fromHex;
#ifdef Q_OS_UNIX
namespace {
enum DebuggerProgram { None, Gdb, Lldb };
#ifdef Q_OS_UNIX
static struct iovec IoVec(struct iovec vec)
{
return vec;
@ -186,10 +188,10 @@ static struct iovec asyncSafeToString(int n, AsyncSafeIntBuffer &&result = Qt::U
r.iov_len = ptr - result.array.data();
return r;
};
}
#endif // Q_OS_UNIX
} // unnamed namespace
static bool debuggerPresent()
static bool alreadyDebugging()
{
#if defined(Q_OS_LINUX)
int fd = open("/proc/self/status", O_RDONLY);
@ -263,10 +265,9 @@ static void disableCoreDump()
}
Q_CONSTRUCTOR_FUNCTION(disableCoreDump);
static std::array<char, 512> stackTraceCommand = {};
static DebuggerProgram debugger = None;
static void prepareStackTrace()
{
stackTraceCommand[0] = '\0';
bool ok = false;
const int disableStackDump = qEnvironmentVariableIntValue("QTEST_DISABLE_STACK_DUMP", &ok);
@ -285,19 +286,15 @@ static void prepareStackTrace()
// prepare the command to be run (our PID shouldn't change!)
# ifdef Q_OS_LINUX
qsnprintf(stackTraceCommand.data(), stackTraceCommand.size(),
"gdb --nx --batch --pid %d -ex 'thread apply all bt' 1>&2",
static_cast<int>(getpid()));
debugger = Gdb;
# elif defined(Q_OS_MACOS)
qsnprintf(stackTraceCommand.data(), stackTraceCommand.size(),
"lldb --batch --no-lldbinit -p %d -o 'bt all' 1>&2",
static_cast<int>(getpid()));
debugger = Lldb;
# endif
}
[[maybe_unused]] static void generateStackTrace()
{
if (stackTraceCommand[0] == '\0' || debuggerPresent())
if (debugger == None || alreadyDebugging())
return;
#if defined(Q_OS_LINUX) || defined(Q_OS_MACOS)
@ -307,13 +304,31 @@ static void prepareStackTrace()
"ms, total time: ", asyncSafeToString(msecsTotalTime),
"ms, dumping stack ===\n");
// execlp() requires null-termination, so call the default constructor
AsyncSafeIntBuffer pidbuffer;
asyncSafeToString(getpid(), std::move(pidbuffer));
// Note: POSIX.1-2001 still has fork() in the list of async-safe functions,
// but in a future edition, it might be removed. It would be safer to wake
// up a babysitter thread to launch the debugger.
pid_t pid = fork();
if (pid == 0) {
// child process
execl("/bin/sh", "/bin/sh", "-c", stackTraceCommand.data(), nullptr);
(void) dup2(STDERR_FILENO, STDOUT_FILENO); // redirect stdout to stderr
switch (debugger) {
case None:
Q_UNREACHABLE();
break;
case Gdb:
execlp("gdb", "gdb", "--nx", "--batch", "-ex", "thread apply all bt",
"--pid", pidbuffer.array.data(), nullptr);
break;
case Lldb:
execlp("lldb", "lldb", "--no-lldbinit", "--batch", "-o", "bt all",
"--attach-pid", pidbuffer.array.data(), nullptr);
break;
}
_exit(1);
} else if (pid < 0) {
writeToStderr("Failed to start debugger.\n");
@ -1615,7 +1630,7 @@ void TestMethods::invokeTests(QObject *testObject) const
m_initTestCaseDataMethod.invoke(testObject, Qt::DirectConnection);
QScopedPointer<WatchDog> watchDog;
if (!debuggerPresent()
if (!alreadyDebugging()
#if QT_CONFIG(valgrind)
&& QBenchmarkGlobalData::current->mode() != QBenchmarkGlobalData::CallgrindChildProcess
#endif