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FileHandle: Refactor file descriptor precondition checks in API calls #1877

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Merged
merged 1 commit into from
Feb 3, 2019
Merged

FileHandle: Refactor file descriptor precondition checks in API calls #1877

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50 changes: 28 additions & 22 deletions Foundation/FileHandle.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -12,29 +12,41 @@ import CoreFoundation
open class FileHandle : NSObject, NSSecureCoding {
#if os(Windows)
private var _handle: HANDLE

@available(windows, unavailable, message: "Cannot perform non-owning handle to fd conversion")
open var fileDescriptor: Int32 {
NSUnsupported()
}

private func _checkFileHandle() {
precondition(_handle != INVALID_HANDLE_VALUE, "Invalid file handle")
}

#else
private var _fd: Int32
#endif
private var _closeOnDealloc: Bool

@available(windows, unavailable,
message: "cannot perform non-owning handle to fd conversion")
open var fileDescriptor: Int32 {
#if os(Windows)
return -1
#else
return _fd
#endif
}

private func _checkFileHandle() {
precondition(_fd >= 0, "Bad file descriptor")
}
#endif

private var _closeOnDealloc: Bool


open var readabilityHandler: ((FileHandle) -> Void)? = {
(FileHandle) -> Void in NSUnimplemented()
}

open var writeabilityHandler: ((FileHandle) -> Void)? = {
(FileHandle) -> Void in NSUnimplemented()
}

open var availableData: Data {
_checkFileHandle()
do {
let readResult = try _readDataOfLength(Int.max, untilEOF: false)
return readResult.toData()
Expand All @@ -44,10 +56,12 @@ open class FileHandle : NSObject, NSSecureCoding {
}

open func readDataToEndOfFile() -> Data {
_checkFileHandle()
return readData(ofLength: Int.max)
}

open func readData(ofLength length: Int) -> Data {
_checkFileHandle()
do {
let readResult = try _readDataOfLength(length, untilEOF: true)
return readResult.toData()
Expand All @@ -58,7 +72,6 @@ open class FileHandle : NSObject, NSSecureCoding {

internal func _readDataOfLength(_ length: Int, untilEOF: Bool, options: NSData.ReadingOptions = []) throws -> NSData.NSDataReadResult {
#if os(Windows)
precondition(_handle != INVALID_HANDLE_VALUE, "invalid file handle")

if length == 0 && !untilEOF {
// Nothing requested, return empty response
Expand Down Expand Up @@ -131,7 +144,6 @@ open class FileHandle : NSObject, NSSecureCoding {
free(buffer)
}
#else
precondition(_fd >= 0, "Bad file descriptor")
if length == 0 && !untilEOF {
// Nothing requested, return empty response
return NSData.NSDataReadResult(bytes: nil, length: 0, deallocator: nil)
Expand Down Expand Up @@ -202,8 +214,8 @@ open class FileHandle : NSObject, NSSecureCoding {
}

open func write(_ data: Data) {
_checkFileHandle()
#if os(Windows)
precondition(_handle != INVALID_HANDLE_VALUE, "invalid file handle")
data.enumerateBytes() { (bytes, range, stop) in
do {
try NSData.write(toHandle: self._handle, path: nil,
Expand All @@ -214,7 +226,6 @@ open class FileHandle : NSObject, NSSecureCoding {
}
}
#else
guard _fd >= 0 else { return }
data.enumerateBytes() { (bytes, range, stop) in
do {
try NSData.write(toFileDescriptor: self._fd, path: nil, buf: UnsafeRawPointer(bytes.baseAddress!), length: bytes.count)
Expand All @@ -228,52 +239,49 @@ open class FileHandle : NSObject, NSSecureCoding {
// TODO: Error handling.

open var offsetInFile: UInt64 {
_checkFileHandle()
#if os(Windows)
precondition(_handle != INVALID_HANDLE_VALUE, "invalid file handle")
var liPointer: LARGE_INTEGER = LARGE_INTEGER(QuadPart: 0)
if SetFilePointerEx(_handle, LARGE_INTEGER(QuadPart: 0),
&liPointer, DWORD(FILE_CURRENT)) == FALSE {
fatalError("SetFilePointerEx failed")
}
return UInt64(liPointer.QuadPart)
#else
precondition(_fd >= 0, "Bad file descriptor")
return UInt64(lseek(_fd, 0, SEEK_CUR))
#endif
}

@discardableResult
open func seekToEndOfFile() -> UInt64 {
_checkFileHandle()
#if os(Windows)
precondition(_handle != INVALID_HANDLE_VALUE, "invalid file handle")
var liPointer: LARGE_INTEGER = LARGE_INTEGER(QuadPart: 0)
if SetFilePointerEx(_handle, LARGE_INTEGER(QuadPart: 0),
&liPointer, DWORD(FILE_END)) == FALSE {
fatalError("SetFilePointerEx failed")
}
return UInt64(liPointer.QuadPart)
#else
precondition(_fd >= 0, "Bad file descriptor")
return UInt64(lseek(_fd, 0, SEEK_END))
#endif
}

open func seek(toFileOffset offset: UInt64) {
_checkFileHandle()
#if os(Windows)
precondition(_handle != INVALID_HANDLE_VALUE, "invalid file handle")
if SetFilePointerEx(_handle, LARGE_INTEGER(QuadPart: LONGLONG(offset)),
nil, DWORD(FILE_BEGIN)) == FALSE {
fatalError("SetFilePointerEx failed")
}
#else
precondition(_fd >= 0, "Bad file descriptor")
lseek(_fd, off_t(offset), SEEK_SET)
#endif
}

open func truncateFile(atOffset offset: UInt64) {
_checkFileHandle()
#if os(Windows)
precondition(_handle != INVALID_HANDLE_VALUE, "invalid file handle")
if SetFilePointerEx(_handle, LARGE_INTEGER(QuadPart: LONGLONG(offset)),
nil, DWORD(FILE_BEGIN)) == FALSE {
fatalError("SetFilePointerEx failed")
Expand All @@ -282,20 +290,18 @@ open class FileHandle : NSObject, NSSecureCoding {
fatalError("SetEndOfFile failed")
}
#else
precondition(_fd >= 0, "Bad file descriptor")
if lseek(_fd, off_t(offset), SEEK_SET) < 0 { fatalError("lseek() failed.") }
if ftruncate(_fd, off_t(offset)) < 0 { fatalError("ftruncate() failed.") }
#endif
}

open func synchronizeFile() {
_checkFileHandle()
#if os(Windows)
precondition(_handle != INVALID_HANDLE_VALUE, "invalid file handle")
if FlushFileBuffers(_handle) == FALSE {
fatalError("FlushFileBuffers failed: \(GetLastError())")
}
#else
precondition(_fd >= 0, "Bad file descriptor")
fsync(_fd)
#endif
}
Expand Down