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https://github.com/apple/container.git
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mazdakandGitHub
bd2c228b57
## Type of Change - [x] Bug fix - [ ] New feature - [ ] Breaking change - [ ] Documentation update ## Description Correct signal semantics for plugins: Container binary currently execs into plugin binaries. If the parent CLI keeps SIGINT/SIGTERM handlers installed, it can intercept/alter signal behavior intended for the plugin (e.g., preventing graceful shutdown in foreground workflows). ## Motivation and Context During the development of a plugin (docker compose compatibility plugin), I encountered a major issues where CTRL-C (SIGTERM) was not being sent to my plugin. CLI plugins, especially those that have long running tasks need a way to handle signals from the OS. Current, we exec into plugin binaries. If the parent CLI keeps SIGINT/SIGTERM handlers installed, it can intercept/alter signal behavior intended for the plugin (e.g., preventing graceful shutdown in foreground workflows). ### What we changed: - Signals handed back to plugins: - DefaultCommand resets SIGINT/SIGTERM to defaults immediately before exec’ing the plugin. - Rationale: since exec replaces the process image, signals should be delivered to (and handled by) the plugin without parent interference. - Non‑plugin commands remain unaffected by this change. - Compatibility: No change to plugin ABI or exec flow. ### Alternatives considered: - Supervising child instead of exec: central forwarding of signals from parent to plugin. Rejected for now to avoid changing process tree/stdio semantics; resetting to defaults before exec preserves current model while fixing signal interference. ## Testing - [X] Tested locally - [ ] Added/updated tests - [ ] Added/updated docs
66 lines
2.4 KiB
Swift
66 lines
2.4 KiB
Swift
//===----------------------------------------------------------------------===//
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// Copyright © 2025 Apple Inc. and the container project authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//===----------------------------------------------------------------------===//
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import ArgumentParser
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import ContainerClient
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import ContainerPlugin
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import Darwin
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struct DefaultCommand: AsyncParsableCommand {
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static let configuration = CommandConfiguration(
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commandName: nil,
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shouldDisplay: false
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)
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@OptionGroup(visibility: .hidden)
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var global: Flags.Global
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@Argument(parsing: .captureForPassthrough)
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var remaining: [String] = []
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func run() async throws {
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// See if we have a possible plugin command.
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let pluginLoader = try? await Application.createPluginLoader()
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guard let command = remaining.first else {
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await Application.printModifiedHelpText(pluginLoader: pluginLoader)
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return
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}
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// Check for edge cases and unknown options to match the behavior in the absence of plugins.
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if command.isEmpty {
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throw ValidationError("Unknown argument '\(command)'")
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} else if command.starts(with: "-") {
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throw ValidationError("Unknown option '\(command)'")
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}
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guard let plugin = pluginLoader?.findPlugin(name: command), plugin.config.isCLI else {
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throw ValidationError("failed to find plugin named container-\(command)")
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}
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// Before execing into the plugin, restore default SIGINT/SIGTERM so the plugin can manage signals.
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Self.resetSignalsForPluginExec()
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// Exec performs execvp (with no fork).
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try plugin.exec(args: remaining)
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}
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}
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extension DefaultCommand {
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// Exposed for tests to verify signal reset semantics.
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static func resetSignalsForPluginExec() {
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signal(SIGINT, SIG_DFL)
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signal(SIGTERM, SIG_DFL)
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}
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}
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