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| 1 | +/* ----------------------------------------------------------------- |
| 2 | + * L o r d O f S c r i p t s (tm) |
| 3 | + * Copyright (C)2024 Dídimo Grimaldo T. |
| 4 | + * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - |
| 5 | + * Implements fs.File interface for BitBucketFS |
| 6 | + *-----------------------------------------------------------------*/ |
| 7 | +package bucketfs |
| 8 | + |
| 9 | +import ( |
| 10 | + "errors" |
| 11 | + "fmt" |
| 12 | + "io" |
| 13 | + "os" |
| 14 | + "sync" |
| 15 | + |
| 16 | + "github.com/lordofscripts/vfs" |
| 17 | +) |
| 18 | + |
| 19 | +/* ---------------------------------------------------------------- |
| 20 | + * G l o b a l s |
| 21 | + *-----------------------------------------------------------------*/ |
| 22 | + |
| 23 | +var ( |
| 24 | + ErrSeek error = errors.New("Seek error") |
| 25 | +) |
| 26 | + |
| 27 | +/* ---------------------------------------------------------------- |
| 28 | + * I n t e r f a c e s |
| 29 | + *-----------------------------------------------------------------*/ |
| 30 | + |
| 31 | +var _ vfs.File = (*BitBucketFile)(nil) |
| 32 | + |
| 33 | +/* ---------------------------------------------------------------- |
| 34 | + * T y p e s |
| 35 | + *-----------------------------------------------------------------*/ |
| 36 | + |
| 37 | +// BitBucketFile mocks a File returning an error on every operation |
| 38 | +// To create a BitBucketFileFS returning a dummy File instead of an error |
| 39 | +// you can your own DummyFS: |
| 40 | +// |
| 41 | +// type writeDummyFS struct { |
| 42 | +// Filesystem |
| 43 | +// } |
| 44 | +// |
| 45 | +// func (fs writeDummyFS) OpenFile(name string, flag int, perm os.FileMode) (File, error) { |
| 46 | +// return DummyFile(dummyError), nil |
| 47 | +// } |
| 48 | + |
| 49 | +// BitBucketFile represents a dummy File |
| 50 | +type BitBucketFile struct { |
| 51 | + name string // name of the fake file |
| 52 | + size int64 // fake size of the file |
| 53 | + at int64 // read pointer of the fake file |
| 54 | + mode int |
| 55 | + perm os.FileMode |
| 56 | + err error // error to return |
| 57 | + mutex *sync.RWMutex |
| 58 | +} |
| 59 | + |
| 60 | +/* ---------------------------------------------------------------- |
| 61 | + * C o n s t r u c t o r s |
| 62 | + *-----------------------------------------------------------------*/ |
| 63 | + |
| 64 | +func newBitBucketFile(name string, flag int, perm os.FileMode, err error) BitBucketFile { |
| 65 | + return BitBucketFile{name, 0, 0, flag, perm & os.ModePerm, err, &sync.RWMutex{}} |
| 66 | +} |
| 67 | + |
| 68 | +/* ---------------------------------------------------------------- |
| 69 | + * M e t h o d s |
| 70 | + *-----------------------------------------------------------------*/ |
| 71 | + |
| 72 | +func (f BitBucketFile) String() string { |
| 73 | + return fmt.Sprintf("::%s %d@%d", f.name, f.size, f.at) |
| 74 | +} |
| 75 | + |
| 76 | +// Name returns the name of the fake file. |
| 77 | +func (f BitBucketFile) Name() string { |
| 78 | + return f.name |
| 79 | +} |
| 80 | + |
| 81 | +// Sync returns an error |
| 82 | +func (f BitBucketFile) Sync() error { |
| 83 | + return f.err |
| 84 | +} |
| 85 | + |
| 86 | +// Truncate reduces the file size to 'size'. |
| 87 | +// Errors: none. |
| 88 | +func (f BitBucketFile) Truncate(size int64) error { |
| 89 | + f.mutex.Lock() |
| 90 | + defer f.mutex.Unlock() |
| 91 | + |
| 92 | + if size < f.size { |
| 93 | + f.size = size |
| 94 | + } |
| 95 | + return nil |
| 96 | +} |
| 97 | + |
| 98 | +// Close closes the file descriptor. |
| 99 | +// Errors: none |
| 100 | +func (f BitBucketFile) Close() error { |
| 101 | + f.mutex.Lock() |
| 102 | + defer f.mutex.Unlock() |
| 103 | + |
| 104 | + f.at = 0 |
| 105 | + return nil |
| 106 | +} |
| 107 | + |
| 108 | +// Write augments the size of the file but does not store any content. |
| 109 | +// Errors: none |
| 110 | +func (f BitBucketFile) Write(p []byte) (n int, err error) { |
| 111 | + f.mutex.Lock() |
| 112 | + defer f.mutex.Unlock() |
| 113 | + |
| 114 | + if p != nil { |
| 115 | + f.size += int64(len(p)) |
| 116 | + } |
| 117 | + return len(p), nil |
| 118 | +} |
| 119 | + |
| 120 | +// Read pretends it read content. |
| 121 | +// Errors: io.EOF |
| 122 | +func (f BitBucketFile) Read(p []byte) (n int, err error) { |
| 123 | + f.mutex.Lock() |
| 124 | + defer f.mutex.Unlock() |
| 125 | + |
| 126 | + remains := f.size - f.at |
| 127 | + if int64(len(p)) < remains { |
| 128 | + f.at += int64(len(p)) |
| 129 | + p = make([]byte, len(p)) |
| 130 | + n = len(p) |
| 131 | + err = nil |
| 132 | + } else { |
| 133 | + f.at = f.size - 1 |
| 134 | + n = int(remains) |
| 135 | + p = make([]byte, n) |
| 136 | + err = errors.Join(io.EOF, f.err) |
| 137 | + } |
| 138 | + return n, err |
| 139 | +} |
| 140 | + |
| 141 | +// ReadAt pretends to read starting at offset. |
| 142 | +// Errors: io.EOF |
| 143 | +func (f BitBucketFile) ReadAt(p []byte, offset int64) (n int, err error) { |
| 144 | + f.mutex.Lock() |
| 145 | + defer f.mutex.Unlock() |
| 146 | + |
| 147 | + if offset < f.size { |
| 148 | + f.at = offset |
| 149 | + return f.Read(p) |
| 150 | + } else { |
| 151 | + n = 0 |
| 152 | + err = errors.Join(io.EOF, f.err) |
| 153 | + } |
| 154 | + return n, f.err |
| 155 | +} |
| 156 | + |
| 157 | +// Seek advances the fake file pointer. |
| 158 | +// Errors. ErrSeek or the error given to the hybrid BitBucketFS constructor. |
| 159 | +func (f BitBucketFile) Seek(offset int64, whence int) (int64, error) { |
| 160 | + f.mutex.Lock() |
| 161 | + defer f.mutex.Unlock() |
| 162 | + |
| 163 | + var newOffset int64 |
| 164 | + if whence == 0 { |
| 165 | + newOffset = offset |
| 166 | + } else if whence == 1 { |
| 167 | + newOffset = f.at + offset |
| 168 | + } else if whence == 2 { |
| 169 | + newOffset = f.size - offset |
| 170 | + } else { |
| 171 | + return 0, f.err |
| 172 | + } |
| 173 | + |
| 174 | + if newOffset < 0 || newOffset >= f.size { |
| 175 | + return 0, errors.Join(f.err, ErrSeek) |
| 176 | + } |
| 177 | + |
| 178 | + f.at = newOffset |
| 179 | + return f.at, nil |
| 180 | +} |
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