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convert the NIOFileSystem example code to a Snippet (#2746)
* convert the NIOFileSystem example code to a Snippet * fix compilation error * add missing license header * exclude snippets from soundness.sh
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| // snippet.hide | ||
| import _NIOFileSystem | ||
| import NIOCore | ||
| // snippet.show | ||
|
|
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| // NIOFileSystem provides access to the local file system via the FileSystem | ||
| // type which is available as a global shared instance. | ||
| let fileSystem = FileSystem.shared | ||
|
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| // Files can be inspected by using 'info': | ||
| if let info = try await fileSystem.info(forFileAt: "/Users/hal9000/demise-of-dave.txt") { | ||
| print("demise-of-dave.txt has type '\(info.type)'") | ||
| } else { | ||
| print("demise-of-dave.txt doesn't exist") | ||
| } | ||
|
|
||
| // Let's find out what's in that file. | ||
| do { | ||
| // Reading a whole file requires a limit. If the file is larger than the limit | ||
| // then an error is thrown. This avoids accidentally consuming too much memory | ||
| // if the file is larger than expected. | ||
| let plan = try await ByteBuffer( | ||
| contentsOf: "/Users/hal9000/demise-of-dave.txt", | ||
| maximumSizeAllowed: .mebibytes(1) | ||
| ) | ||
| print("Plan for Dave's demise:", String(decoding: plan.readableBytesView, as: UTF8.self)) | ||
| } catch let error as FileSystemError where error.code == .notFound { | ||
| // All errors thrown by the module have type FileSystemError (or | ||
| // Swift.CancellationError). It looks like the file doesn't exist. Let's | ||
| // create it now. | ||
| // | ||
| // The code above for reading the file is shorthand for opening the file in | ||
| // read-only mode and then reading its contents. The FileSystemProtocol | ||
| // has a few different 'withFileHandle' methods for opening a file in different | ||
| // modes. Let's open a file for writing, creating it at the same time. | ||
| try await fileSystem.withFileHandle( | ||
| forWritingAt: "/Users/hal9000/demise-of-dave.txt", | ||
| options: .newFile(replaceExisting: false) | ||
| ) { file in | ||
| let plan = ByteBuffer(string: "TODO...") | ||
| try await file.write(contentsOf: plan.readableBytesView, toAbsoluteOffset: 0) | ||
| } | ||
| } | ||
|
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||
| // Directories can be opened like regular files but they cannot be read from or | ||
| // written to. However, their contents can be listed: | ||
| let path: FilePath? = try await fileSystem.withDirectoryHandle(atPath: "/Users/hal9000/Music") { directory in | ||
| for try await entry in directory.listContents() { | ||
| if entry.name.extension == "mp3", entry.name.stem.contains("daisy") { | ||
| // Found it! | ||
| return entry.path | ||
| } | ||
| } | ||
| // No luck. | ||
| return nil | ||
| } | ||
|
|
||
| if let path = path { | ||
| print("Found file at '\(path)'") | ||
| } | ||
|
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||
| // The file system can also be used to perform the following operations on files | ||
| // and directories: | ||
| // - copy, | ||
| // - remove, | ||
| // - rename, and | ||
| // - replace. | ||
| // | ||
| // Here's an example of copying a directory: | ||
| try await fileSystem.copyItem(at: "/Users/hal9000/Music", to: "/Volumes/Tardis/Music") | ||
|
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| // Symbolic links can also be created (and read with 'destinationOfSymbolicLink(at:)'). | ||
| try await fileSystem.createSymbolicLink(at: "/Users/hal9000/Backup", withDestination: "/Volumes/Tardis") | ||
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||
| // Opening a symbolic link opens its destination so in most cases there's no | ||
| // need to read the destination of a symbolic link: | ||
| try await fileSystem.withDirectoryHandle(atPath: "/Users/hal9000/Backup") { directory in | ||
| // Beyond listing the contents of a directory, the directory handle provides a | ||
| // number of other functions, many of which are also available on regular file | ||
| // handles. | ||
| // | ||
| // This includes getting information about a file, such as its permissions, last access time, | ||
| // and last modification time: | ||
| let info = try await directory.info() | ||
| print("The directory has permissions '\(info.permissions)'") | ||
|
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||
| // Where supported, the extended attributes of a file can also be accessed, read, and modified: | ||
| for attribute in try await directory.attributeNames() { | ||
| let value = try await directory.valueForAttribute(attribute) | ||
| print("Extended attribute '\(attribute)' has value '\(value)'") | ||
| } | ||
|
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||
| // Once this closure returns the file system will close the directory handle freeing | ||
| // any resources required to access it such as file descriptors. Handles can also be opened | ||
| // with the 'openFile' and 'openDirectory' APIs but that places the onus you to close the | ||
| // handle at an appropriate time to avoid leaking resources. | ||
| } |
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