/
TargetLinux.swift
232 lines (195 loc) · 7.1 KB
/
TargetLinux.swift
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
//===--- TargetLinux.swift - Represents a process we are inspecting -------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2022 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// Defines `Target`, which represents the process we are inspecting.
// This is the Linux version.
//
//===----------------------------------------------------------------------===//
#if os(Linux)
import Glibc
import _Backtracing
@_spi(Internal) import _Backtracing
@_spi(Contexts) import _Backtracing
@_spi(MemoryReaders) import _Backtracing
@_spi(Utils) import _Backtracing
@_implementationOnly import Runtime
struct TargetThread {
typealias ThreadID = pid_t
var id: ThreadID
var context: HostContext?
var name: String
var backtrace: SymbolicatedBacktrace
}
class Target {
typealias Address = UInt64
var pid: pid_t
var name: String
var signal: UInt64
var faultAddress: Address
var crashingThread: TargetThread.ThreadID
var images: [Backtrace.Image] = []
var threads: [TargetThread] = []
var crashingThreadNdx: Int = -1
var signalName: String {
switch signal {
case UInt64(SIGQUIT): return "SIGQUIT"
case UInt64(SIGABRT): return "SIGABRT"
case UInt64(SIGBUS): return "SIGBUS"
case UInt64(SIGFPE): return "SIGFPE"
case UInt64(SIGILL): return "SIGILL"
case UInt64(SIGSEGV): return "SIGSEGV"
case UInt64(SIGTRAP): return "SIGTRAP"
default: return "\(signal)"
}
}
var signalDescription: String {
switch signal {
case UInt64(SIGQUIT): return "Terminated"
case UInt64(SIGABRT): return "Aborted"
case UInt64(SIGBUS): return "Bus error"
case UInt64(SIGFPE): return "Floating point exception"
case UInt64(SIGILL): return "Illegal instruction"
case UInt64(SIGSEGV): return "Bad pointer dereference"
case UInt64(SIGTRAP): return "System trap"
default:
return "Signal \(signal)"
}
}
var reader: MemserverMemoryReader
// Get the name of a process
private static func getProcessName(pid: pid_t) -> String {
let path = "/proc/\(pid)/comm"
guard let name = readString(from: path) else {
return ""
}
return String(stripWhitespace(name))
}
/// Get the name of a thread
private func getThreadName(tid: Int64) -> String {
let path = "/proc/\(pid)/task/\(tid)/comm"
guard let name = readString(from: path) else {
return ""
}
let trimmed = String(stripWhitespace(name))
// Allow the main thread to use the process' name, but other
// threads will have an empty name unless they've set the name
// explicitly
if trimmed == self.name && pid != tid {
return ""
}
return trimmed
}
init(crashInfoAddr: UInt64, limit: Int?, top: Int, cache: Bool) {
// fd #4 is reserved for the memory server
let memserverFd: CInt = 4
pid = getppid()
reader = MemserverMemoryReader(fd: memserverFd)
name = Self.getProcessName(pid: pid)
let crashInfo: CrashInfo
do {
crashInfo = try reader.fetch(from: crashInfoAddr, as: CrashInfo.self)
} catch {
print("swift-backtrace: unable to fetch crash info.")
exit(1)
}
crashingThread = TargetThread.ThreadID(crashInfo.crashing_thread)
signal = crashInfo.signal
faultAddress = crashInfo.fault_address
images = Backtrace.captureImages(using: reader,
forProcess: Int(pid))
do {
try fetchThreads(threadListHead: Address(crashInfo.thread_list),
limit: limit, top: top, cache: cache)
} catch {
print("swift-backtrace: failed to fetch thread information: \(error)")
exit(1)
}
}
/// Fetch information about all of the process's threads; the crash_info
/// structure contains a linked list of thread ucontexts, which may not
/// include every thread. In particular, if a thread was stuck in an
/// uninterruptible wait, we won't have a ucontext for it.
func fetchThreads(
threadListHead: Address,
limit: Int?, top: Int, cache: Bool
) throws {
var next = threadListHead
while next != 0 {
let t = try reader.fetch(from: next, as: thread.self)
next = t.next
guard let ucontext
= try? reader.fetch(from: t.uctx, as: ucontext_t.self) else {
// This can happen if a thread is in an uninterruptible wait
continue
}
let context = HostContext.fromHostMContext(ucontext.uc_mcontext)
let backtrace = try Backtrace.capture(from: context,
using: reader,
images: images,
limit: limit,
top: top)
guard let symbolicated
= backtrace.symbolicated(with: images,
sharedCacheInfo: nil,
useSymbolCache: cache) else {
print("unable to symbolicate backtrace for thread \(t.tid)")
exit(1)
}
threads.append(TargetThread(id: TargetThread.ThreadID(t.tid),
context: context,
name: getThreadName(tid: t.tid),
backtrace: symbolicated))
}
// Sort the threads by thread ID; the main thread always sorts
// lower than any other.
threads.sort {
return $0.id == pid || ($1.id != pid && $0.id < $1.id)
}
// Find the crashing thread index
if let ndx = threads.firstIndex(where: { $0.id == crashingThread }) {
crashingThreadNdx = ndx
} else {
print("unable to find the crashing thread")
exit(1)
}
}
func redoBacktraces(limit: Int?, top: Int, cache: Bool) {
for (ndx, thread) in threads.enumerated() {
guard let context = thread.context else {
continue
}
guard let backtrace = try? Backtrace.capture(from: context,
using: reader,
images: images,
limit: limit,
top: top) else {
print("unable to capture backtrace from context for thread \(ndx)")
continue
}
guard let symbolicated = backtrace.symbolicated(with: images,
sharedCacheInfo: nil,
useSymbolCache: cache) else {
print("unable to symbolicate backtrace from context for thread \(ndx)")
continue
}
threads[ndx].backtrace = symbolicated
}
}
func withDebugger(_ body: () -> ()) throws {
print("""
From another shell, please run
lldb --attach-pid \(pid) -o c
""")
body()
}
}
#endif // os(Linux)