mirror of https://github.com/ceph/go-ceph
90 lines
2.2 KiB
Go
90 lines
2.2 KiB
Go
package cutil
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// #include <stdlib.h>
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import "C"
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import (
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"unsafe"
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)
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// BufferGroup is a helper structure that holds Go-allocated slices of
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// C-allocated strings and their respective lengths. Useful for C functions
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// that consume byte buffers with explicit length instead of null-terminated
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// strings. When used as input arguments in C functions, caller must make sure
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// the C code will not hold any pointers to either of the struct's attributes
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// after that C function returns.
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type BufferGroup struct {
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// C-allocated buffers.
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Buffers []CharPtr
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// Lengths of C buffers, where Lengths[i] = length(Buffers[i]).
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Lengths []SizeT
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}
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// TODO: should BufferGroup implementation change and the slices would contain
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// nested Go pointers, they must be pinned with PtrGuard.
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// NewBufferGroupStrings returns new BufferGroup constructed from strings.
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func NewBufferGroupStrings(strs []string) *BufferGroup {
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s := &BufferGroup{
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Buffers: make([]CharPtr, len(strs)),
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Lengths: make([]SizeT, len(strs)),
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}
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for i, str := range strs {
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bs := []byte(str)
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s.Buffers[i] = CharPtr(C.CBytes(bs))
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s.Lengths[i] = SizeT(len(bs))
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}
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return s
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}
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// NewBufferGroupBytes returns new BufferGroup constructed
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// from slice of byte slices.
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func NewBufferGroupBytes(bss [][]byte) *BufferGroup {
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s := &BufferGroup{
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Buffers: make([]CharPtr, len(bss)),
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Lengths: make([]SizeT, len(bss)),
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}
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for i, bs := range bss {
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s.Buffers[i] = CharPtr(C.CBytes(bs))
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s.Lengths[i] = SizeT(len(bs))
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}
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return s
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}
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// Free free()s the C-allocated memory.
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func (s *BufferGroup) Free() {
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for _, ptr := range s.Buffers {
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C.free(unsafe.Pointer(ptr))
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}
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s.Buffers = nil
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s.Lengths = nil
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}
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// BuffersPtr returns a pointer to the beginning of the Buffers slice.
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func (s *BufferGroup) BuffersPtr() CharPtrPtr {
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if len(s.Buffers) == 0 {
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return nil
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}
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return CharPtrPtr(&s.Buffers[0])
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}
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// LengthsPtr returns a pointer to the beginning of the Lengths slice.
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func (s *BufferGroup) LengthsPtr() SizeTPtr {
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if len(s.Lengths) == 0 {
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return nil
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}
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return SizeTPtr(&s.Lengths[0])
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}
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func testBufferGroupGet(s *BufferGroup, index int) (str string, length int) {
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bs := C.GoBytes(unsafe.Pointer(s.Buffers[index]), C.int(s.Lengths[index]))
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return string(bs), int(s.Lengths[index])
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}
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