FileUtils.swift 4.19 KB
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/*Copyright (C) 2016 Drew Crawford
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation  and/or other materials provided with the distribution.
3. Neither the names of the copyright holders nor the names of any
   contributors may be used to endorse or promote products derived from this
   software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.*/

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#if os(OSX)
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import Darwin
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#elseif os(Linux)
import Glibc
#endif
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enum FileUtilsError: ErrorProtocol {
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    case OpenError(Int, String)
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    case ReadError(Int)
    case CloseError(Int)
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    case WriteError(Int)
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    case UTF8Error
}

extension String {
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    init(file fileName: String) throws {
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        let file = open(fileName, O_RDONLY)
        var completeFile: [CChar]  = []
        //CANNOT defer cleaning up this resource
        //PAY ATTENTION
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        if file == -1 { throw FileUtilsError.OpenError(Int(errno), fileName) }
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        readLoop: while true {
            var buf = [CChar](repeating: 0, count: 4096)
            let bytesRead = buf.withUnsafeMutableBufferPointer {
                return read(file, $0.baseAddress, $0.count)
            }
            switch(bytesRead) {
                case 0:
                break readLoop //EOF

                case -1:
                close(file) //CLEAN UP open resource
                throw FileUtilsError.ReadError(Int(errno))

                default:
                completeFile.append(contentsOf: buf[0..<bytesRead])
            }
        }
        // holy shit, UB if we don't append a zero here
        // https://lists.swift.org/pipermail/swift-dev/Week-of-Mon-20160404/001633.html
        completeFile.append(0)
        guard let str = String(validatingUTF8: completeFile) else {
            close(file)
            throw FileUtilsError.UTF8Error
        }

        self.init(str)
        if close(file) != 0 {
            throw FileUtilsError.CloseError(Int(errno))
        }
    }
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    func write(file fileName: String) throws {
        #if os(OSX)
        let os_write = Darwin.write
        #elseif os(Linux)
        let os_write = Glibc.write
        #endif
        let file = open(fileName,O_WRONLY | O_CREAT, 0o600)
        //CANNOT defer cleaning up this resource
        //PAY ATTENTION
        if file == -1 { throw FileUtilsError.OpenError(Int(errno), fileName) }
        let length = self.utf8.count
        let bytesWritten = self.withCString() {(ptr) -> Int in
            return os_write(file, ptr, length)
        }
        if bytesWritten != self.utf8.count {
            close(file) //CLEAN UP open resource
            throw FileUtilsError.WriteError(Int(errno))
        }
        if close(file) != 0 {
            throw FileUtilsError.CloseError(Int(errno))
        }
    }
}

extension String {
    ///The location of the directory for the item.
    var directoryPath: String {
        var position = self.characters.endIndex
        for (x,c) in self.characters.reversed().enumerated() {
            if c == "/" {
                return String(self.characters[self.characters.startIndex..<position])
            }
            position = position.predecessor()
        }
        return self
    }
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}