go.mway.dev/x@v0.0.0-20240520034138-950aede9a3fb/os/write_file.go (about) 1 // Copyright (c) 2024 Matt Way 2 // 3 // Permission is hereby granted, free of charge, to any person obtaining a copy 4 // of this software and associated documentation files (the "Software"), to 5 // deal in the Software without restriction, including without limitation the 6 // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 7 // sell copies of the Software, and to permit persons to whom the Software is 8 // furnished to do so, subject to the following conditions: 9 // 10 // The above copyright notice and this permission notice shall be included in 11 // all copies or substantial portions of the Software. 12 // 13 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 14 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 15 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 16 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 17 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 18 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 19 // IN THE THE SOFTWARE. 20 21 package os 22 23 import ( 24 "io" 25 "os" 26 27 "go.mway.dev/errors" 28 ) 29 30 const ( 31 // DefaultWriteFlags are default flags used for writing to a file. 32 DefaultWriteFlags = os.O_CREATE | os.O_TRUNC | os.O_WRONLY 33 34 _fileMode = 0o644 35 ) 36 37 var ( 38 // ErrNilWriteReader indicates that a given reader value is nil or produced 39 // a nil reader. 40 ErrNilWriteReader = errors.New("nil write reader provided") 41 // ErrUnsupportedWriteReader indicates that a given value is not a 42 // supported write reader type. 43 ErrUnsupportedWriteReader = errors.New("unsupported write reader") 44 ) 45 46 // ReaderFunc is a function that returns an [io.Reader] or an error. 47 type ReaderFunc = func() (io.Reader, error) 48 49 // ReadCloserFunc is a function that returns an [io.ReadCloser] or an error. 50 type ReadCloserFunc = func() (io.ReadCloser, error) 51 52 // WriteReaderToFileWithFlags creates path with flags and mode, and copies the 53 // given reader to it. 54 func WriteReaderToFileWithFlags( 55 path string, 56 reader any, 57 flags int, 58 mode os.FileMode, 59 ) (written int, err error) { 60 var src io.Reader 61 switch t := reader.(type) { 62 case io.ReadCloser: 63 defer func() { 64 err = errors.Join(err, t.Close()) 65 }() 66 src = t 67 case io.Reader: 68 src = t 69 case ReadCloserFunc: 70 var tmp io.ReadCloser 71 if tmp, err = t(); err != nil { 72 return 0, err 73 } 74 defer func() { 75 err = errors.Join(err, tmp.Close()) 76 }() 77 src = tmp 78 case ReaderFunc: 79 if src, err = t(); err != nil { 80 return 0, err 81 } 82 default: 83 return 0, errors.Wrapf(ErrUnsupportedWriteReader, "%T", src) 84 } 85 86 var dst io.WriteCloser 87 if dst, err = os.OpenFile(path, flags, mode); err != nil { 88 return 0, err 89 } 90 defer func() { 91 err = errors.Join(err, dst.Close()) 92 }() 93 94 var n int64 95 n, err = io.Copy(dst, src) 96 return int(n), err 97 } 98 99 // WriteReaderToFile creates path and copies the given reader to it. 100 func WriteReaderToFile(path string, reader any) (written int, err error) { 101 return WriteReaderToFileWithFlags( 102 path, 103 reader, 104 DefaultWriteFlags, 105 _fileMode, 106 ) 107 }