src/developer/debug/zxdb/console/format_thread.cc

// Copyright 2025 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <optional>
#include <utility>

#include "src/developer/debug/ipc/records.h"
#include "src/developer/debug/zxdb/client/frame.h"
#include "src/developer/debug/zxdb/client/process.h"
#include "src/developer/debug/zxdb/client/session.h"
#include "src/developer/debug/zxdb/client/source_file_provider_impl.h"
#include "src/developer/debug/zxdb/client/thread.h"
#include "src/developer/debug/zxdb/console/command_utils.h"
#include "src/developer/debug/zxdb/console/console_context.h"
#include "src/developer/debug/zxdb/console/format_context.h"
#include "src/developer/debug/zxdb/console/format_exception.h"
#include "src/developer/debug/zxdb/console/format_location.h"
#include "src/developer/debug/zxdb/console/format_target.h"
#include "src/lib/fxl/strings/string_printf.h"

namespace zxdb {

namespace {

// We want to display full information for some exceptions like page faults, but debugger exceptions
// like single step and debug breakpoint exceptions don't need thhe full treatment to reduce noise
// when stepping.
bool ShouldDisplayFullExceptionInfo(const StopInfo& info) {
  if (info.exception_type == debug_ipc::ExceptionType::kNone ||
      info.exception_type == debug_ipc::ExceptionType::kHardwareBreakpoint ||
      info.exception_type == debug_ipc::ExceptionType::kSoftwareBreakpoint ||
      info.exception_type == debug_ipc::ExceptionType::kWatchpoint ||
      info.exception_type == debug_ipc::ExceptionType::kSingleStep ||
      info.exception_type == debug_ipc::ExceptionType::kSynthetic)
    return false;
  return true;
}

OutputBuffer DescribeHitBreakpoints(ConsoleContext* context,
                                    const std::vector<fxl::WeakPtr<Breakpoint>>& hits) {
  // Do two passes since some of the weak pointers may be gone.
  std::vector<int> ids;
  for (const auto& hit : hits) {
    if (hit)
      ids.push_back(context->IdForBreakpoint(hit.get()));
  }

  OutputBuffer out;
  if (ids.empty())
    return out;

  out.Append("on bp ");
  for (size_t i = 0; i < ids.size(); i++) {
    out.Append(Syntax::kSpecial, std::to_string(ids[i]));
    if (i < ids.size() - 1)
      out.Append(", ");
  }
  out.Append(" ");
  return out;
}

}  // namespace

// For comparison, GDB's printout for a breakpoint hit is:
//
//   Breakpoint 1, main () at eraseme.c:4
//   4         printf("Hello\n");
//
// And LLDB's is:
//
//   * thread #1: tid = 33767, 0x000055555555463e a.out`main + 4 at
//   eraseme.c:4, name = 'a.out', stop reason = breakpoint 1.1
//       frame #0: 0x000055555555463e a.out`main + 4 at eraseme.c:4
//      1    #include <stdio.h>
//      2
//      3    int main() {
//   -> 4    printf("Hello\n");
//      5    return 1;
//      6  }
//
// When stepping, GDB prints out only the 2nd line with source info, and LLDB
// prints out the whole thing with "step over" for "stop reason".
OutputBuffer FormatThreadStop(ConsoleContext* context, const Thread* thread,
                              std::optional<StopInfo> info, bool override_show_exception_info) {
  OutputBuffer out;

  std::optional<StopInfo> maybe_stop_info = std::move(info);

  if (!maybe_stop_info) {
    maybe_stop_info = thread->CurrentStopInfo();
  }

  if (maybe_stop_info && ShouldDisplayFullExceptionInfo(*maybe_stop_info) &&
      !override_show_exception_info) {
    out.Append(FormatException(context, thread, maybe_stop_info->exception_record));
    out.Append("\n");
  }

  out.Append("🛑 ");

  // Only print out the process/thread when there's more than one.
  if (context->session()->system().GetTargets().size() > 1) {
    const Target* target = context->GetActiveTarget();
    out.Append("process ");
    out.Append(Syntax::kSpecial, std::to_string(context->IdForTarget(target)));
    out.Append(" ");
  }
  if (thread->GetProcess()->GetThreads().size() > 1) {
    out.Append("thread ");
    out.Append(Syntax::kSpecial, std::to_string(context->IdForThread(thread)));
    out.Append(" ");
  }

  // Stop reason.
  if (maybe_stop_info && !maybe_stop_info->hit_breakpoints.empty()) {
    out.Append(DescribeHitBreakpoints(context, maybe_stop_info->hit_breakpoints));
  } else if (maybe_stop_info &&
             maybe_stop_info->exception_type == debug_ipc::ExceptionType::kGeneral &&
             !override_show_exception_info) {
    // Show exception type for non-debug exceptions. Most exceptions are generated by the debugger
    // internally so skip those to avoid noise.
    out.Append(fxl::StringPrintf(
        "on %s exception ", debug_ipc::ExceptionTypeToString(maybe_stop_info->exception_type)));
  }

  // Frame (current position will always be frame 0).
  const Stack& stack = thread->GetStack();
  if (stack.empty()) {
    out.Append(" (no location information)\n");
  } else {
    size_t frame_id = context->GetActiveFrameIdForThread(thread);
    const Location& location = stack[frame_id]->GetLocation();

    FormatLocationOptions location_options(thread->GetProcess()->GetTarget());
    location_options.func.name.bold_last = true;
    out.Append(FormatLocation(location, location_options));

    if (location.has_symbols()) {
      out.Append("\n");
    } else {
      out.Append(" (no symbol info)\n");
    }

    Err err = OutputSourceContext(
        thread->GetProcess(),
        std::make_unique<SourceFileProviderImpl>(thread->GetProcess()->GetTarget()->settings()),
        location, context->GetSourceAffinityForThread(thread));
    if (err.has_error())
      out.Append(err);
  }
  return out;
}

OutputBuffer FormatThreadConcise(const ConsoleContext* context, const Thread* thread) {
  OutputBuffer out("Thread ");
  out.Append(Syntax::kSpecial, std::to_string(context->IdForThread(thread)));

  out.Append(Syntax::kVariable, " state");
  out.Append("=" + FormatConsoleString(
                       ThreadStateToString(thread->GetState(), thread->GetBlockedReason())));

  const char* id_name = debug::PlatformThreadIdName(context->session()->platform(), false);
  out.Append(" ");
  out.Append(Syntax::kVariable, id_name);
  out.Append("=" + std::to_string(thread->GetKoid()));

  out.Append(Syntax::kVariable, " name");
  out.Append("=" + FormatConsoleString(thread->GetName()));

  return out;
}

}  // namespace zxdb