Function defaultPanic [src]

Dumps a stack trace to standard error, then aborts.
Prototype

pub fn defaultPanic( msg: []const u8, first_trace_addr: ?usize, ) noreturn
Parameters

msg: []const u8first_trace_addr: ?usize
Source

  pub fn defaultPanic(
    msg: []const u8,
    first_trace_addr: ?usize,
) noreturn {
    @branchHint(.cold);

    // For backends that cannot handle the language features depended on by the
    // default panic handler, we have a simpler panic handler:
    switch (builtin.zig_backend) {
        .stage2_aarch64,
        .stage2_arm,
        .stage2_powerpc,
        .stage2_riscv64,
        .stage2_spirv,
        .stage2_wasm,
        .stage2_x86,
        => @trap(),
        .stage2_x86_64 => switch (builtin.target.ofmt) {
            .elf, .macho => {},
            else => @trap(),
        },
        else => {},
    }

    switch (builtin.os.tag) {
        .freestanding, .other => {
            @trap();
        },
        .uefi => {
            const uefi = std.os.uefi;

            var utf16_buffer: [1000]u16 = undefined;
            const len_minus_3 = std.unicode.utf8ToUtf16Le(&utf16_buffer, msg) catch 0;
            utf16_buffer[len_minus_3..][0..3].* = .{ '\r', '\n', 0 };
            const len = len_minus_3 + 3;
            const exit_msg = utf16_buffer[0 .. len - 1 :0];

            // Output to both std_err and con_out, as std_err is easier
            // to read in stuff like QEMU at times, but, unlike con_out,
            // isn't visible on actual hardware if directly booted into
            inline for ([_]?*uefi.protocol.SimpleTextOutput{ uefi.system_table.std_err, uefi.system_table.con_out }) |o| {
                if (o) |out| {
                    out.setAttribute(.{ .foreground = .red }) catch {};
                    _ = out.outputString(exit_msg) catch {};
                    out.setAttribute(.{ .foreground = .white }) catch {};
                }
            }

            if (uefi.system_table.boot_services) |bs| {
                // ExitData buffer must be allocated using boot_services.allocatePool (spec: page 220)
                const exit_data = uefi.raw_pool_allocator.dupeZ(u16, exit_msg) catch @trap();
                bs.exit(uefi.handle, .aborted, exit_data) catch {};
            }
            @trap();
        },
        .cuda, .amdhsa => std.posix.abort(),
        .plan9 => {
            var status: [std.os.plan9.ERRMAX]u8 = undefined;
            const len = @min(msg.len, status.len - 1);
            @memcpy(status[0..len], msg[0..len]);
            status[len] = 0;
            std.os.plan9.exits(status[0..len :0]);
        },
        else => {},
    }

    if (enable_segfault_handler) {
        // If a segfault happens while panicking, we want it to actually segfault, not trigger
        // the handler.
        resetSegfaultHandler();
    }

    // Note there is similar logic in handleSegfaultPosix and handleSegfaultWindowsExtra.
    nosuspend switch (panic_stage) {
        0 => {
            panic_stage = 1;

            _ = panicking.fetchAdd(1, .seq_cst);

            {
                const stderr = lockStderrWriter(&.{});
                defer unlockStderrWriter();

                if (builtin.single_threaded) {
                    stderr.print("panic: ", .{}) catch posix.abort();
                } else {
                    const current_thread_id = std.Thread.getCurrentId();
                    stderr.print("thread {} panic: ", .{current_thread_id}) catch posix.abort();
                }
                stderr.print("{s}\n", .{msg}) catch posix.abort();

                if (@errorReturnTrace()) |t| dumpStackTrace(t.*);
                dumpCurrentStackTraceToWriter(first_trace_addr orelse @returnAddress(), stderr) catch {};
            }

            waitForOtherThreadToFinishPanicking();
        },
        1 => {
            panic_stage = 2;

            // A panic happened while trying to print a previous panic message.
            // We're still holding the mutex but that's fine as we're going to
            // call abort().
            fs.File.stderr().writeAll("aborting due to recursive panic\n") catch {};
        },
        else => {}, // Panicked while printing the recursive panic message.
    };

    posix.abort();
}  