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mirror of https://github.com/Oxalide/vsphere-influxdb-go.git synced 2023-10-10 13:36:51 +02:00
vsphere-influxdb-go/vendor/github.com/influxdata/influxdb/pkg/mmap/mmap_windows.go
2017-10-25 20:52:40 +00:00

47 lines
912 B
Go

package mmap
import (
"os"
"syscall"
"unsafe"
)
// Map memory-maps a file.
func Map(path string) ([]byte, error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
defer f.Close()
fi, err := f.Stat()
if err != nil {
return nil, err
} else if fi.Size() == 0 {
return nil, nil
}
lo, hi := uint32(fi.Size()), uint32(fi.Size()>>32)
fmap, err := syscall.CreateFileMapping(syscall.Handle(f.Fd()), nil, syscall.PAGE_READONLY, hi, lo, nil)
if err != nil {
return nil, err
}
defer syscall.CloseHandle(fmap)
ptr, err := syscall.MapViewOfFile(fmap, syscall.FILE_MAP_READ, 0, 0, uintptr(fi.Size()))
if err != nil {
return nil, err
}
data := (*[1 << 30]byte)(unsafe.Pointer(ptr))[:fi.Size()]
return data, nil
}
// Unmap closes the memory-map.
func Unmap(data []byte) error {
if data == nil {
return nil
}
return syscall.UnmapViewOfFile(uintptr(unsafe.Pointer(&data[0])))
}