trap SIGSEGV, SIGBUS and SIGFPE by default, in addition to SIGILL (#58)

motivation: print crash trace on segmentation faults and other common failures beyond illegal instructions

changes:
* include SIGSEGV, SIGBUS and SIGFPE in the default signals trapped
* update and improve tests

Sources/Backtrace/Backtrace.swift

@@ -67,9 +67,9 @@ private func printBacktrace(signal: CInt) {
 }
 
 public enum Backtrace {
-    /// Install the backtrace handler on `SIGILL`.
+    /// Install the backtrace handler on default signals: `SIGILL`, `SIGSEGV`, `SIGBUS`, `SIGFPE`.
     public static func install() {
-        Backtrace.install(signals: [SIGILL])
+        Backtrace.install(signals: [SIGILL, SIGSEGV, SIGBUS, SIGFPE])
     }
 
     /// Install the backtrace handler when any of `signals` happen.

Sources/Sample/main.swift

@@ -13,7 +13,28 @@
 //===----------------------------------------------------------------------===//
 
 import Backtrace
+#if canImport(Darwin)
+import Darwin
+#elseif os(Linux)
+import Glibc
+#endif
 
-let reason = CommandLine.arguments.count == 2 ? CommandLine.arguments[1] : "unknown"
 Backtrace.install()
-fatalError(reason)
+
+func raiseSignal(_ signal: Int32) {
+    raise(signal)
+}
+
+let reason = CommandLine.arguments.count == 2 ? CommandLine.arguments[1] : "unknown"
+switch reason.uppercased() {
+case "SIGILL":
+    raiseSignal(SIGILL)
+case "SIGSEGV":
+    raiseSignal(SIGSEGV)
+case "SIGBUS":
+    raiseSignal(SIGBUS)
+case "SIGFPE":
+    raiseSignal(SIGFPE)
+default:
+    fatalError(reason)
+}

Tests/BacktraceTests/BacktraceTests+XCTest.swift

@@ -25,7 +25,11 @@ import XCTest
 extension BacktraceTests {
     public static var allTests: [(String, (BacktraceTests) -> () throws -> Void)] {
         return [
-            ("testBacktrace", testBacktrace),
+            ("testFatalError", testFatalError),
+            ("testSIGILL", testSIGILL),
+            ("testSIGSEGV", testSIGSEGV),
+            ("testSIGBUS", testSIGBUS),
+            ("testSIGFPE", testSIGFPE),
         ]
     }
 }

Tests/BacktraceTests/BacktraceTests.swift

@@ -15,22 +15,76 @@
 import XCTest
 
 public final class BacktraceTests: XCTestCase {
-    func testBacktrace() {
-        #if os(Linux)
+    func testFatalError() throws {
+        #if !os(Linux)
+        try XCTSkipIf(true, "test is only supported on Linux")
+        #endif
+
         let expectedError = UUID().uuidString
-        let pipe = Pipe()
-        let process = Process()
-        process.executableURL = URL(fileURLWithPath: "/usr/bin/swift")
-        process.arguments = ["run", "Sample", expectedError]
-        process.standardError = pipe
-        XCTAssertNoThrow(try process.run())
-        if process.isRunning {
-            process.waitUntilExit()
-        }
-        let stderr = String(data: pipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8) ?? ""
+        let stderr = try runSample(reason: expectedError)
         print(stderr)
+
+        XCTAssert(stderr.contains("Received signal 4. Backtrace:"))
         XCTAssert(stderr.contains("Current stack trace:"), "expected stanard error to include backtrace")
         XCTAssert(stderr.contains("Fatal error: \(expectedError)"), "expected stanard error to include error information")
+    }
+
+    func testSIGILL() throws {
+        #if !os(Linux)
+        try XCTSkipIf(true, "test is only supported on Linux")
+        #endif
+
+        let stderr = try runSample(reason: "SIGILL")
+        print(stderr)
+
+        XCTAssert(stderr.contains("Received signal \(SIGILL). Backtrace:"))
+        XCTAssert(stderr.contains("Sample.raiseSignal"))
+    }
+
+    func testSIGSEGV() throws {
+        #if !os(Linux)
+        try XCTSkipIf(true, "test is only supported on Linux")
+        #endif
+
+        let stderr = try runSample(reason: "SIGSEGV")
+        print(stderr)
+
+        XCTAssert(stderr.contains("Received signal \(SIGSEGV). Backtrace:"))
+        XCTAssert(stderr.contains("Sample.raiseSignal"))
+    }
+
+    func testSIGBUS() throws {
+        #if !os(Linux)
+        try XCTSkipIf(true, "test is only supported on Linux")
+        #endif
+
+        let stderr = try runSample(reason: "SIGBUS")
+        print(stderr)
+
+        XCTAssert(stderr.contains("Received signal \(SIGBUS). Backtrace:"))
+        XCTAssert(stderr.contains("Sample.raiseSignal"))
+    }
+
+    func testSIGFPE() throws {
+        #if !os(Linux)
+        try XCTSkipIf(true, "test is only supported on Linux")
         #endif
+
+        let stderr = try runSample(reason: "SIGFPE")
+        print(stderr)
+
+        XCTAssert(stderr.contains("Received signal \(SIGFPE). Backtrace:"))
+        XCTAssert(stderr.contains("Sample.raiseSignal"))
+    }
+
+    func runSample(reason: String) throws -> String {
+        let pipe = Pipe()
+        let process = Process()
+        process.executableURL = URL(fileURLWithPath: "/usr/bin/swift")
+        process.arguments = ["run", "Sample", reason]
+        process.standardError = pipe
+        try process.run()
+        process.waitUntilExit()
+        return String(data: pipe.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8) ?? ""
     }
 }

docker/docker-compose.yaml

@@ -34,4 +34,4 @@ services:
 
   shell:
     <<: *common
-    entrypoint: /bin/bash
+    entrypoint: /bin/bash -l