go.mway.dev/x@v0.0.0-20240520034138-950aede9a3fb/os/stream_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 "errors" 25 "io" 26 "io/fs" 27 "os" 28 ) 29 30 const _createFileFlags = os.O_CREATE | os.O_TRUNC | os.O_WRONLY 31 32 // WithFileReader opens the file at path for reading and passes the file's 33 // reader to fn, cleaning up once fn returns. WithFileReader returns any error 34 // returned by fn as well as any other errors encountered. 35 func WithFileReader(path string, fn func(r io.Reader) error) (err error) { 36 var src io.ReadCloser 37 if src, err = os.Open(path); err != nil { 38 return 39 } 40 defer func() { 41 err = errors.Join(err, src.Close()) 42 }() 43 44 return fn(src) 45 } 46 47 // WithFileWriter opens the file at path for writing and passes the file's 48 // writer to fn, cleaning up once fn returns. WithFileWriter returns any error 49 // returned by fn as well as any other errors encountered. 50 func WithFileWriter(path string, fn func(w io.Writer) error) (err error) { 51 return WithFileModeWriter(path, 0o744, fn) 52 } 53 54 // WithFileModeWriter opens (creating with the given mode or truncating, as 55 // necessary) the file at path for writing and passes the file's writer to fn, 56 // cleaning up once fn returns. WithFileModeWriter returns any error returned 57 // by fn as well as any other errors encountered. 58 func WithFileModeWriter( 59 path string, 60 mode fs.FileMode, 61 fn func(w io.Writer) error, 62 ) (err error) { 63 var dst io.WriteCloser 64 if dst, err = os.OpenFile(path, _createFileFlags, mode); err != nil { 65 return 66 } 67 defer func() { 68 err = errors.Join(err, dst.Close()) 69 }() 70 71 return fn(dst) 72 }