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SR-14953: Data.write(to:) fails when writing to /dev/stdout #3022

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Merged
merged 1 commit into from
Aug 2, 2021
Merged

SR-14953: Data.write(to:) fails when writing to /dev/stdout #3022

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9 changes: 8 additions & 1 deletion Sources/Foundation/FileHandle.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -595,7 +595,14 @@ open class FileHandle : NSObject {
throw _NSErrorWithWindowsError(GetLastError(), reading: false)
}
#else
guard fsync(_fd) >= 0 else { throw _NSErrorWithErrno(errno, reading: false) }
// Linux, macOS, OpenBSD return -1 and errno == EINVAL if trying to sync a special file,
// eg a fifo, character device etc which can be ignored.
// Additionally, Linux may return EROFS if tying to sync on a readonly filesystem, which also can be ignored.
// macOS can also return ENOTSUP for pipes but dont ignore it, so that the behaviour matches Darwin's Foundation.
if fsync(_fd) < 0 {
if errno == EINVAL || errno == EROFS { return }
throw _NSErrorWithErrno(errno, reading: false)
}
#endif
}

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7 changes: 7 additions & 0 deletions Tests/Foundation/Tests/TestFileHandle.swift
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Expand Up @@ -613,6 +613,12 @@ class TestFileHandle : XCTestCase {
}
#endif

func testSynchronizeOnSpecialFile() throws {
// .synchronize() on a special file shouldnt fail
let fh = try XCTUnwrap(FileHandle(forWritingAtPath: "/dev/stdout"))
XCTAssertNoThrow(try fh.synchronize())
}

static var allTests : [(String, (TestFileHandle) -> () throws -> ())] {
var tests: [(String, (TestFileHandle) -> () throws -> ())] = [
("testReadUpToCount", testReadUpToCount),
Expand All @@ -632,6 +638,7 @@ class TestFileHandle : XCTestCase {
("test_waitForDataInBackgroundAndNotify", test_waitForDataInBackgroundAndNotify),
/* ⚠️ */ ("test_readWriteHandlers", testExpectedToFail(test_readWriteHandlers,
/* ⚠️ */ "<rdar://problem/50860781> sporadically times out")),
("testSynchronizeOnSpecialFile", testSynchronizeOnSpecialFile),
]

#if NS_FOUNDATION_ALLOWS_TESTABLE_IMPORT
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6 changes: 6 additions & 0 deletions Tests/Foundation/Tests/TestNSData.swift
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Expand Up @@ -237,6 +237,7 @@ class TestNSData: LoopbackServerTest {
("test_writeToURLOptions", test_writeToURLOptions),
("test_writeToURLPermissions", test_writeToURLPermissions),
("test_writeToURLPermissionsWithAtomic", test_writeToURLPermissionsWithAtomic),
("test_writeToURLSpecialFile", test_writeToURLSpecialFile),
("test_edgeNoCopyDescription", test_edgeNoCopyDescription),
("test_initializeWithBase64EncodedDataGetsDecodedData", test_initializeWithBase64EncodedDataGetsDecodedData),
("test_initializeWithBase64EncodedDataWithNonBase64CharacterIsNil", test_initializeWithBase64EncodedDataWithNonBase64CharacterIsNil),
Expand Down Expand Up @@ -623,6 +624,11 @@ class TestNSData: LoopbackServerTest {
#endif
}

func test_writeToURLSpecialFile() {
let url = URL(fileURLWithPath: "/dev/stdout")
XCTAssertNoThrow(try Data("Output to STDOUT\n".utf8).write(to: url))
}

func test_emptyDescription() {
let expected = "<>"

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