Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-12-08 06:10:04 +00:00
Code Issues Projects Releases Packages Wiki Activity

{net,os/user,plugin}: eliminate unnecessary C round-trips

Browse source 
We're making two extra round-trips to C to malloc and free strings
that originate in Go and don't escape. Skip those round-trips by
allocating null-terminated slices in Go memory instead.

Change-Id: I9e4c5ad999a7924ba50b82293c52073ec75518be
Reviewed-on: https://go-review.googlesource.com/56530
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Bryan C. Mills 2017-05-13 00:01:50 -04:00 • committed by Bryan Mills
parent 6711fa70ce
commit d5b0ec858b
4 changed files with 38 additions and 36 deletions
Download patch file Download diff file Expand all files Collapse all files

33
src/plugin/plugin_dlopen.go
View file

@ -81,16 +81,16 @@ func pathToPrefix(s string) string {
}
func open(name string) (*Plugin, error) {
cPath := (*C.char)(C.malloc(C.PATH_MAX + 1))
defer C.free(unsafe.Pointer(cPath))
cRelName := C.CString(name)
defer C.free(unsafe.Pointer(cRelName))
if C.realpath(cRelName, cPath) == nil {
cPath := make([]byte, C.PATH_MAX+1)
cRelName := make([]byte, len(name)+1)
copy(cRelName, name)
if C.realpath(
(*C.char)(unsafe.Pointer(&cRelName[0])),
(*C.char)(unsafe.Pointer(&cPath[0]))) == nil {
return nil, errors.New("plugin.Open(" + name + "): realpath failed")
}
filepath := C.GoString(cPath)
filepath := C.GoString((*C.char)(unsafe.Pointer(&cPath[0])))
pluginsMu.Lock()
if p := plugins[filepath]; p != nil {
@ -99,7 +99,7 @@ func open(name string) (*Plugin, error) {
return p, nil
}
var cErr *C.char
h := C.pluginOpen(cPath, &cErr)
h := C.pluginOpen((*C.char)(unsafe.Pointer(&cPath[0])), &cErr)
if h == 0 {
pluginsMu.Unlock()
return nil, errors.New("plugin.Open: " + C.GoString(cErr))
@ -127,9 +127,11 @@ func open(name string) (*Plugin, error) {
plugins[filepath] = p
pluginsMu.Unlock()
initStr := C.CString(pluginpath + ".init")
initFuncPC := C.pluginLookup(h, initStr, &cErr)
C.free(unsafe.Pointer(initStr))
initStr := make([]byte, len(pluginpath)+6)
copy(initStr, pluginpath)
copy(initStr[len(pluginpath):], ".init")
initFuncPC := C.pluginLookup(h, (*C.char)(unsafe.Pointer(&initStr[0])), &cErr)
if initFuncPC != nil {
initFuncP := &initFuncPC
initFunc := *(*func())(unsafe.Pointer(&initFuncP))
@ -144,9 +146,12 @@ func open(name string) (*Plugin, error) {
delete(syms, symName)
symName = symName[1:]
}
cname := C.CString(pathToPrefix(pluginpath) + "." + symName)
p := C.pluginLookup(h, cname, &cErr)
C.free(unsafe.Pointer(cname))
fullName := pathToPrefix(pluginpath) + "." + symName
cname := make([]byte, len(fullName)+1)
copy(cname, fullName)
p := C.pluginLookup(h, (*C.char)(unsafe.Pointer(&cname[0])), &cErr)
if p == nil {
return nil, errors.New("plugin.Open: could not find symbol " + symName + ": " + C.GoString(cErr))
}