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Revert: iOS: Switch logging from syslog to os_log #190643

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Merged
cbracken merged 1 commit into from
Aug 6, 2026
+6 −39
Merged

Revert: iOS: Switch logging from syslog to os_log #190643

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34 changes: 5 additions & 29 deletions engine/src/flutter/shell/platform/darwin/common/framework/Source/Logger.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,6 @@

import Darwin
import Foundation
import os

/// The level of logging severity.
///
Expand Down Expand Up @@ -77,7 +76,7 @@ import os
#if os(iOS)
// On iOS, the user has no access to stdout.
// Output can be read from the log by the user or the `flutter` tool.
self.init(outputWriter: OSLogOutputWriter(), logLevel: .info)
self.init(outputWriter: SyslogOutputWriter(), logLevel: .info)
#elseif os(macOS)
// On macOS, both the user and the tool read from stdout.
self.init(outputWriter: StdoutOutputWriter(), logLevel: .info)
Expand Down Expand Up @@ -183,34 +182,11 @@ protocol OutputWriter: Sendable {
func writeLine(level: LogLevel, _ message: String)
}

private extension LogLevel {
/// The `OSLogType` used to emit a message at this level via `os_log`.
///
/// `OSLogType` is not a strict severity ladder like `LogLevel`. It's a small set of categories
/// with differing persistence and display behavior. Each level therefore maps to the type with
/// the closest semantics rather than a matching severity.
///
/// - `.info` is buffered in memory and not written to persistent store by default.
/// - `.warning` is written to persistent store.
/// - `.error` is logged with error metadata and is written to persistent store.
/// - `.important` is used by Dart `print` output, so is written to persistent store.
/// - `.fatal` is logged with fault metadata and is written to persistent store.
var osLogType: OSLogType {
switch self {
case .info: return .info
case .warning: return .default
case .error: return .error
case .important: return .default
case .fatal: return .fault
}
}
}

final class OSLogOutputWriter: OutputWriter, Sendable {
private let osLog = OSLog(subsystem: "io.flutter.flutter", category: "flutter")

final class SyslogOutputWriter: OutputWriter, Sendable {
func writeLine(level: LogLevel, _ message: String) {
os_log("%{public}@", log: osLog, type: level.osLogType, message)
// TODO(cbracken): replace this with os_log-based approach.
// https://github.com/flutter/flutter/issues/44030
message.withCString { vsyslog(LOG_ALERT, "%s", getVaList([$0])) }
}
}

Expand Down
11 changes: 1 addition & 10 deletions engine/src/flutter/shell/platform/darwin/common/framework/Source/LoggerTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -7,10 +7,7 @@ import Foundation
import Testing
@testable import test_utils_swift

// Several tests mutate shared `Logger` singleton properties (`outputWriter`, `logLevel`).
// Even though those mutations are all lock-guarded and thread-safe, we serialize the tests to keep
// them from racing each other.
@Suite(.serialized) struct LoggerTests {
@Suite struct LoggerTests {
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@Test func testInitialization() {
let writer = StringOutputWriter()
Expand Down Expand Up @@ -138,10 +135,4 @@ import Testing
// races or crashes.
#expect(Logger.logLevel == .info || Logger.logLevel == .warning)
}

@Test func testDefaultInitialization() {
let logger = Logger()
#expect(logger.logLevel == .info)
logger.log(level: .info, "Test default logger")
}
}