mirror of https://github.com/ceph/go-ceph
79 lines
1.7 KiB
Go
79 lines
1.7 KiB
Go
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package cutil
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/*
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#include <stdlib.h>
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#include <sys/uio.h>
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*/
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import "C"
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import (
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"unsafe"
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)
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var iovecSize uintptr
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// StructIovecPtr is an unsafe pointer wrapping C's `*struct iovec`.
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type StructIovecPtr unsafe.Pointer
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// Iovec helps manage struct iovec arrays needed by some C functions.
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type Iovec struct {
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// cvec represents an array of struct iovec C memory
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cvec unsafe.Pointer
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// length of the array (in elements)
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length int
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}
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// NewIovec creates an Iovec, and underlying C memory, of the specified size.
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func NewIovec(l int) *Iovec {
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r := &Iovec{
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cvec: C.malloc(C.size_t(l) * C.size_t(iovecSize)),
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length: l,
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}
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return r
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}
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// ByteSlicesToIovec takes a slice of byte slices and returns a new iovec that
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// maps the slice data to struct iovec entries.
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func ByteSlicesToIovec(data [][]byte) *Iovec {
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iov := NewIovec(len(data))
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for i := range data {
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iov.Set(i, data[i])
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}
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return iov
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}
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// Pointer returns a StructIovecPtr that represents the C memory of the
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// underlying array.
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func (v *Iovec) Pointer() StructIovecPtr {
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return StructIovecPtr(unsafe.Pointer(v.cvec))
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}
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// Len returns the number of entries in the Iovec.
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func (v *Iovec) Len() int {
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return v.length
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}
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// Free the C memory in the Iovec.
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func (v *Iovec) Free() {
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if v.cvec != nil {
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C.free(v.cvec)
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v.cvec = nil
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v.length = 0
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}
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}
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// Set will map the memory of the given byte slice to the iovec at the
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// specified position.
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func (v *Iovec) Set(i int, buf []byte) {
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offset := uintptr(i) * iovecSize
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iov := (*C.struct_iovec)(unsafe.Pointer(
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uintptr(unsafe.Pointer(v.cvec)) + offset))
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iov.iov_base = unsafe.Pointer(&buf[0])
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iov.iov_len = C.size_t(len(buf))
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}
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func init() {
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var iovec C.struct_iovec
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iovecSize = unsafe.Sizeof(iovec)
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}
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