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28 lines
749 B
28 lines
749 B
package local
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import (
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"os"
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"syscall"
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"unsafe"
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)
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func Fallocate(file *os.File, offset int64, length int64) error {
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var fst syscall.Fstore_t
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fst.Flags = syscall.F_ALLOCATECONTIG
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fst.Posmode = syscall.F_PREALLOCATE
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fst.Offset = 0
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fst.Length = offset + length
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fst.Bytesalloc = 0
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// Check https://lists.apple.com/archives/darwin-dev/2007/Dec/msg00040.html
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_, _, err := syscall.Syscall(syscall.SYS_FCNTL, file.Fd(), syscall.F_PREALLOCATE, uintptr(unsafe.Pointer(&fst)))
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if err != syscall.Errno(0x0) {
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fst.Flags = syscall.F_ALLOCATEALL
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// Ignore the return value
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_, _, _ = syscall.Syscall(syscall.SYS_FCNTL, file.Fd(), syscall.F_PREALLOCATE, uintptr(unsafe.Pointer(&fst)))
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}
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return syscall.Ftruncate(int(file.Fd()), fst.Length)
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}
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