go-ceph/internal/cutil/command_output.go
John Mulligan e2a78eec02 cutil: allow passing free functions to command output type
The *_command functions in librados and libcephfs document the use
of specific free functions for data allocated. These functions are
currently just wrappers around C's free() function. However, to be
more strictly compliant this change adds a free-function callback
to the CommandOutput type and the specific free functions are now
used outside the unit tests.

Signed-off-by: John Mulligan <jmulligan@redhat.com>
2020-05-12 17:18:08 -04:00

101 lines
2.6 KiB
Go

package cutil
/*
#include <stdlib.h>
*/
import "C"
import (
"unsafe"
)
// CommandOutput can be used to manage the outputs of ceph's *_command
// functions.
type CommandOutput struct {
free FreeFunc
outBuf *C.char
outBufLen C.size_t
outs *C.char
outsLen C.size_t
}
// NewCommandOutput returns an empty CommandOutput. The pointers that
// a CommandOutput provides can be used to get the results of ceph's
// *_command functions.
func NewCommandOutput() *CommandOutput {
return &CommandOutput{
free: free,
}
}
// SetFreeFunc sets the function used to free memory held by CommandOutput.
// Not all uses of CommandOutput expect to use the basic C.free function
// and either require or prefer the use of a custom deallocation function.
// Use SetFreeFunc to change the free function and return the modified
// CommandOutput object.
func (co *CommandOutput) SetFreeFunc(f FreeFunc) *CommandOutput {
co.free = f
return co
}
// Free any C memory tracked by this object.
func (co *CommandOutput) Free() {
if co.outBuf != nil {
co.free(unsafe.Pointer(co.outBuf))
}
if co.outs != nil {
co.free(unsafe.Pointer(co.outs))
}
}
// OutBuf returns an unsafe wrapper around a pointer to a `char*`.
func (co *CommandOutput) OutBuf() CharPtrPtr {
return CharPtrPtr(&co.outBuf)
}
// OutBufLen returns an unsafe wrapper around a pointer to a size_t.
func (co *CommandOutput) OutBufLen() SizeTPtr {
return SizeTPtr(&co.outBufLen)
}
// Outs returns an unsafe wrapper around a pointer to a `char*`.
func (co *CommandOutput) Outs() CharPtrPtr {
return CharPtrPtr(&co.outs)
}
// OutsLen returns an unsafe wrapper around a pointer to a size_t.
func (co *CommandOutput) OutsLen() SizeTPtr {
return SizeTPtr(&co.outsLen)
}
// GoValues returns native go values converted from the internal C-language
// values tracked by this object.
func (co *CommandOutput) GoValues() (buf []byte, status string) {
if co.outBufLen > 0 {
buf = C.GoBytes(unsafe.Pointer(co.outBuf), C.int(co.outBufLen))
}
if co.outsLen > 0 {
status = C.GoStringN(co.outs, C.int(co.outsLen))
}
return buf, status
}
// testSetString is only used by the unit tests for this file.
// It is located here due to the restriction on having import "C" in
// go test files. :-(
// It mimics a C function that takes a pointer to a
// string and length and allocates memory and sets the pointers
// to the new string and its length.
func testSetString(strp CharPtrPtr, lenp SizeTPtr, s string) {
sp := (**C.char)(strp)
lp := (*C.size_t)(lenp)
*sp = C.CString(s)
*lp = C.size_t(len(s))
}
// free wraps C.free.
// Required for unit tests that may not use cgo directly.
func free(p unsafe.Pointer) {
C.free(p)
}