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@paperclover
paperclover committed Apr 13, 2024
1 parent fb77fee commit f9d1ee6
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Showing 4 changed files with 133 additions and 108 deletions.
2 changes: 2 additions & 0 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -555,6 +555,7 @@ else()
add_compile_definitions("BUN_DEBUG=1")
set(ASSERT_ENABLED "1")
endif()

message(STATUS "Using WebKit from ${WEBKIT_DIR}")
else()
if(NOT EXISTS "${WEBKIT_DIR}/lib/${libWTF}.${STATIC_LIB_EXT}" OR NOT EXISTS "${WEBKIT_DIR}/lib/${libJavaScriptCore}.${STATIC_LIB_EXT}")
Expand Down Expand Up @@ -762,6 +763,7 @@ if(NOT NO_CODEGEN)
"${BUN_SRC}/js/node/*.ts"
"${BUN_SRC}/js/thirdparty/*.js"
"${BUN_SRC}/js/thirdparty/*.ts"
"${BUN_SRC}/js/internal-for-testing.ts"
)

file(GLOB CODEGEN_FILES ${CONFIGURE_DEPENDS} "${BUN_CODEGEN_SRC}/*.ts")
Expand Down
225 changes: 117 additions & 108 deletions src/crash_handler.zig
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Original file line number Diff line number Diff line change
@@ -1,20 +1,19 @@
//! This file contains Bun's crash handler. In debug builds, we are able to
//! print backtraces that are mapped to source code. In a release mode, we do
//! not have that information in the binary. Bun's solution to this is called
//! a "trace string", a compressed and url-safe encoding of a captured
//! backtrace. Version 1 tracestrings contain the following information:
//! print backtraces that are mapped to source code. In release builds, we do
//! not have debug symbols in the binary. Bun's solution to this is called
//! a "trace string", a url with compressed encoding of the captured
//! backtrace. Version 1 trace strings contain the following information:
//!
//! - What version and commit of Bun captured the backtrace.
//! - The platform the backtrace was captured on.
//! - The list of addresses with ASLR removed, ready to be remapped.
//! - If panicking, the message that was panicked with.
//! - List of feature-flags that were marked.
//!
//! These can be demangled using Bun's remapping API, which has cached
//! versions of all debug symbols for all versions of Bun. Hosting this keeps
//! users from having to download symbols, which can be very large.
//!
//! The remapper is open source: https://github.com/oven-sh/bun-report
//! The remapper is open source: https://github.com/oven-sh/bun.report
//!
//! A lot of this handler is based on the Zig Standard Library implementation
//! for std.debug.panicImpl and their code for gathering backtraces.
Expand Down Expand Up @@ -50,7 +49,7 @@ var panic_mutex = std.Thread.Mutex{};
/// This is used to catch and handle panics triggered by the panic handler.
threadlocal var panic_stage: usize = 0;

/// This structure and formatter must be kept in sync with `bun-report`'s decoder.
/// This structure and formatter must be kept in sync with `bun.report`'s decoder implementation.
pub const CrashReason = union(enum) {
/// From @panic()
panic: []const u8,
Expand Down Expand Up @@ -193,7 +192,6 @@ pub fn crashHandler(
};

if (debug_trace) {
// TODO: On Windows, there are sometimes issues remapping information here:
dumpStackTrace(trace.*);
} else {
writer.writeAll("Please report this panic as a GitHub issue using this link:\n") catch std.os.abort();
Expand Down Expand Up @@ -221,7 +219,7 @@ pub fn crashHandler(
}

// Be aware that this function only lets one thread return from it.
// This is important sot hat we do not try to run the reload logic twice.
// This is important so that we do not try to run the following reload logic twice.
waitForOtherThreadToFinishPanicking();

if (bun.auto_reload_on_crash and
Expand Down Expand Up @@ -253,6 +251,8 @@ pub fn crashHandler(
const stderr = std.io.getStdErr().writer();
stderr.print("\npanic: {s}\n", .{reason}) catch std.os.abort();
stderr.print("panicked during a panic. Aborting.\n", .{}) catch std.os.abort();

std.debug.dumpCurrentStackTrace(@returnAddress());
},
3 => {
// Panicked while printing "Panicked during a panic."
Expand Down Expand Up @@ -499,11 +499,11 @@ pub fn handleRootError(err: anyerror, error_return_trace: ?*std.builtin.StackTra
},

error.MissingPackageJSON => {
Output.err(
"MissingPackageJSON",
"Bun could not find a package.json file.",
Output.errGeneric(
"Bun could not find a package.json file to install from",
.{},
);
Output.note("Run \"bun init\" to initialize a project", .{});
},

else => {
Expand Down Expand Up @@ -744,7 +744,7 @@ const tracestr_header = std.fmt.comptimePrint(
},
);

const Address = union(enum) {
const StackLine = union(enum) {
unknown,
known: struct {
address: i32,
Expand All @@ -753,82 +753,35 @@ const Address = union(enum) {
},
javascript,

pub fn writeEncoded(self: Address, writer: anytype) !void {
switch (self) {
.unknown => try writer.writeAll("_"),
.known => |known| {
if (known.object) |object| {
try SourceMap.encodeVLQ(1).writeTo(writer);
try SourceMap.encodeVLQ(@intCast(object.len)).writeTo(writer);
try writer.writeAll(object);
}
try SourceMap.encodeVLQ(known.address).writeTo(writer);
},
.javascript => {
try writer.writeAll("=");
},
}
}

pub fn format(self: Address, comptime _: []const u8, _: std.fmt.FormatOptions, writer: anytype) !void {
switch (self) {
.unknown => try writer.print("unknown address", .{}),
.known => |known| try writer.print("0x{x} @ {s}", .{ known.address, known.object orelse "bun" }),
.javascript => try writer.print("javascript address", .{}),
}
}
};

const TraceString = struct {
trace: *std.builtin.StackTrace,
reason: CrashReason,
action: Action,

const Action = enum {
/// Open a pre-filled GitHub issue with the expanded trace
open_issue,
/// View the trace with nothing else
view_trace,
};

pub fn format(self: TraceString, comptime _: []const u8, _: std.fmt.FormatOptions, writer: anytype) !void {
try encodeTraceString(self, writer);
}
};

fn encodeTraceString(opts: TraceString, writer: anytype) !void {
try writer.writeAll(report_base_url ++ tracestr_header);

const image_path = if (bun.Environment.isWindows) bun.windows.exePathW() else null;

var name_bytes: [512]u16 = undefined;
var name_bytes_utf8: [1024]u8 = undefined;

for (opts.trace.instruction_addresses[0..opts.trace.index]) |addr| {
const address: Address = switch (bun.Environment.os) {
.windows => addr: {
pub fn fromAddress(addr: usize, name_bytes: []const u8) StackLine {
return switch (bun.Environment.os) {
.windows => {
const module = bun.windows.getModuleHandleFromAddress(addr) orelse {
// TODO: try to figure out of this is a JS stack frame
break :addr .{ .unknown = {} };
return .{ .unknown = {} };
};

const base_address = @intFromPtr(module);
const name = bun.windows.getModuleNameW(module, &name_bytes) orelse
break :addr .{ .unknown = {} };

break :addr .{
var temp: [512]u16 = undefined;
const name = bun.windows.getModuleNameW(module, &temp) orelse
return .{ .unknown = {} };

const image_path = bun.windows.exePathW();

return .{
.mapped = .{
// To remap this, `pdb-addr2line --exe bun.pdb 0x123456`
.address = addr - base_address,

.object = if (!std.mem.eql(u16, name, image_path)) name: {
const basename = name[std.mem.lastIndexOfAny(u16, name, "\\/") orelse 0 ..];
break :name bun.strings.convertUTF8toUTF16InBuffer(&name_bytes_utf8, basename);
break :name bun.strings.convertUTF8toUTF16InBuffer(&name_bytes, basename);
} else null,
},
};
},
.mac => addr: {
.mac => {
// This code is slightly modified from std.debug.DebugInfo.lookupModuleNameDyld
// https://github.com/ziglang/zig/blob/215de3ee67f75e2405c177b262cb5c1cd8c8e343/lib/std/debug.zig#L1783
const address = if (addr == 0) 0 else addr - 1;
Expand Down Expand Up @@ -861,39 +814,45 @@ fn encodeTraceString(opts: TraceString, writer: anytype) !void {
const seg_end = seg_start + segment_cmd.vmsize;
if (original_address >= seg_start and original_address < seg_end) {
// Subtract ASLR value for stable address
const stable_address: isize = @intCast(address - vmaddr_slide);
// Subtract base address for compactness
// To remap this, `llvm-symbolizer --obj bun-with-symbols --relative-address 0x123456`
const relative_address: i32 = @intCast(stable_address - @as(isize, @intCast(base_address)));

if (relative_address < 0) break;

const object = if (i == 0)
null // zero is the main binary
else
std.fs.path.basename(bun.sliceTo(std.c._dyld_get_image_name(i), 0));

break :addr .{ .known = .{
.object = object,
.address = relative_address,
} };
const stable_address: usize = @intCast(address - vmaddr_slide);

if (i == 0) {
const image_relative_address = stable_address - seg_start;
if (image_relative_address > std.math.maxInt(i32)) {
return .{ .unknown = {} };
}

// To remap this, you have to add the offset (which is going to be 0x100000000),
// and then you can run it through `llvm-symbolizer --obj bun-with-symbols 0x123456`
// The reason we are subtracting this known offset is mostly just so that we can
// fit it within a signed 32-bit integer. The VLQs will be shorter too.
return .{ .known = .{
.object = null,
.address = @intCast(image_relative_address),
} };
} else {
// these libraries are not interesting, mark as unknown
return .{ .unknown = {} };
}

return .{ .unknown = {} };
}
},
else => {},
};
}

break :addr .{ .unknown = {} };
return .{ .unknown = {} };
},
else => addr: {
else => {
// This code is slightly modified from std.debug.DebugInfo.lookupModuleDl
// https://github.com/ziglang/zig/blob/215de3ee67f75e2405c177b262cb5c1cd8c8e343/lib/std/debug.zig#L2024
var ctx: struct {
// Input
address: usize,
i: usize = 0,
// Output
result: Address = .{ .unknown = {} },
result: StackLine = .{ .unknown = {} },
} = .{ .address = addr -| 1 };
const CtxTy = @TypeOf(ctx);

Expand All @@ -918,19 +877,70 @@ fn encodeTraceString(opts: TraceString, writer: anytype) !void {
}
}.callback) catch {};

break :addr ctx.result;
return ctx.result;
},
};
}

try address.writeEncoded(writer);
pub fn writeEncoded(self: StackLine, writer: anytype) !void {
switch (self) {
.unknown => try writer.writeAll("_"),
.known => |known| {
if (known.object) |object| {
try SourceMap.encodeVLQ(1).writeTo(writer);
try SourceMap.encodeVLQ(@intCast(object.len)).writeTo(writer);
try writer.writeAll(object);
}
try SourceMap.encodeVLQ(known.address).writeTo(writer);
},
.javascript => {
try writer.writeAll("=");
},
}
}

pub fn format(self: StackLine, comptime _: []const u8, _: std.fmt.FormatOptions, writer: anytype) !void {
switch (self) {
.unknown => try writer.print("unknown address", .{}),
.known => |known| try writer.print("0x{x} @ {s}", .{ known.address, known.object orelse "bun" }),
.javascript => try writer.print("javascript address", .{}),
}
}
};

const TraceString = struct {
trace: *std.builtin.StackTrace,
reason: CrashReason,
action: Action,

const Action = enum {
/// Open a pre-filled GitHub issue with the expanded trace
open_issue,
/// View the trace with nothing else
view_trace,
};

pub fn format(self: TraceString, comptime _: []const u8, _: std.fmt.FormatOptions, writer: anytype) !void {
try encodeTraceString(self, writer);
}
};

fn encodeTraceString(opts: TraceString, writer: anytype) !void {
try writer.writeAll(report_base_url ++ tracestr_header);

var name_bytes: [1024]u8 = undefined;

for (opts.trace.instruction_addresses[0..opts.trace.index]) |addr| {
const line = StackLine.fromAddress(addr, &name_bytes);
try line.writeEncoded(writer);
}

try writer.writeAll(comptime zero_vlq: {
const vlq = SourceMap.encodeVLQ(0);
break :zero_vlq vlq.bytes[0..vlq.len];
});

// The following switch must be kept in sync with `bun-report`'s decoder.
// The following switch must be kept in sync with `bun.report`'s decoder implementation.
switch (opts.reason) {
.panic => |message| {
try writer.writeByte('0');
Expand Down Expand Up @@ -995,7 +1005,7 @@ fn encodeTraceString(opts: TraceString, writer: anytype) !void {

fn writeU64AsTwoVLQs(writer: anytype, addr: usize) !void {
const first = SourceMap.encodeVLQ(@intCast((addr & 0xFFFFFFFF00000000) >> 32));
const second = SourceMap.encodeVLQ(@intCast(addr & 0xFFFFFFFF));
const second = SourceMap.encodeVLQ(@bitCast(@as(u32, @intCast(addr & 0xFFFFFFFF))));
try first.writeTo(writer);
try second.writeTo(writer);
}
Expand All @@ -1008,14 +1018,6 @@ fn crash() noreturn {
std.os.abort();
},
else => {
// Parts of this is copied from std.os.abort (linux non libc path) and WTFCrash
// Cause a segfault to make sure a core dump is generated if such is enabled

// Only one thread may proceed to the rest of abort().
const global = struct {
var abort_entered: bool = false;
};
while (@cmpxchgWeak(bool, &global.abort_entered, false, true, .SeqCst, .SeqCst)) |_| {}

// Install default handler so that the tkill below will terminate.
const sigact = std.os.Sigaction{ .handler = .{ .handler = std.os.SIG.DFL }, .mask = std.os.empty_sigset, .flags = 0 };
Expand All @@ -1031,10 +1033,7 @@ fn crash() noreturn {
std.os.sigaction(sig, &sigact, null) catch {};
}

@as(*allowzero volatile u8, @ptrFromInt(0xDEADBEEF)).* = 0;
std.os.raise(std.os.SIG.SEGV) catch {};
@as(*allowzero volatile u8, @ptrFromInt(0)).* = 0;
std.c._exit(127);
@trap();
},
}
}
Expand Down Expand Up @@ -1128,3 +1127,13 @@ pub fn dumpStackTrace(trace: std.builtin.StackTrace) void {
}
stdDumpStackTrace(trace);
}

pub fn jsGetMachOImageZeroOffset(_: *bun.JSC.JSGlobalObject, _: *bun.JSC.CallFrame) bun.JSC.JSValue {
if (!bun.Environment.isMac) return .undefined;

const header = std.c._dyld_get_image_header(0) orelse return .undefined;
const base_address = @intFromPtr(header);
const vmaddr_slide = std.c._dyld_get_image_vmaddr_slide(0);

return bun.JSC.JSValue.jsNumber(base_address - vmaddr_slide);
}
6 changes: 6 additions & 0 deletions src/js/internal-for-testing.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,3 +21,9 @@ export const shellInternals = {
lex: $newZigFunction("shell.zig", "TestingAPIs.shellLex", 1),
parse: $newZigFunction("shell.zig", "TestingAPIs.shellParse", 1),
};

export const getMachOImageZeroOffset = $newZigFunction(
"crash_handler.zig",
"jsGetMachOImageZeroOffset",
0,
) as () => number;
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