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package getgr
import (
"syscall"
"unsafe"
)
//#define _POSIX_SOURCE // for getgrnam_r(3) in grp.h
//#include <stdlib.h> // for free(3)
//#include <unistd.h> // for sysconf(3)
//#include <grp.h> // for getgrnam_r(3)
//static char *strary(char **ary, unsigned int n) { return ary[n]; }
import "C"
type Gid uint
type Group struct {
Name string
Passwd string
Gid Gid
Mem []string
}
func strary(c **C.char) (g []string) {
g = make([]string, 0)
for i := C.uint(0); true; i++ {
cstr := C.strary(c, i)
if cstr == nil {
return
}
g = append(g, C.GoString(cstr))
}
panic("not reached")
}
// A wrapper around C getgrnam_r
func ByName(name string) (*Group, error) {
nameC := C.CString(name)
defer C.free(unsafe.Pointer(nameC))
buflen := C.sysconf(C._SC_GETGR_R_SIZE_MAX)
if buflen < 1 {
buflen = 1024
}
buf := make([]byte, buflen)
var grp C.struct_group
var ret *C.struct_group
for {
success, errno := C.getgrnam_r(nameC, &grp, (*C.char)(unsafe.Pointer(&buf[0])), C.size_t(buflen), &ret)
if success >= 0 {
break
}
if errno == syscall.ERANGE {
buflen += 256
buf = make([]byte, buflen)
} else {
return nil, errno
}
}
if ret == nil {
return nil, nil
}
return &Group{
Name: C.GoString(ret.gr_name),
Passwd: C.GoString(ret.gr_passwd),
Gid: Gid(ret.gr_gid),
Mem: strary(ret.gr_mem),
}, nil
}
// A wrapper around C getgrgid_r
func ByGid(gid int32) (*Group, error) {
gidC := C.__gid_t(gid)
buflen := C.sysconf(C._SC_GETGR_R_SIZE_MAX)
if buflen < 1 {
buflen = 1024
}
buf := make([]byte, buflen)
var grp C.struct_group
var ret *C.struct_group
for {
success, errno := C.getgrgid_r(gidC, &grp, (*C.char)(unsafe.Pointer(&buf[0])), C.size_t(buflen), &ret)
if success >= 0 {
break
}
if errno == syscall.ERANGE {
buflen += 256
buf = make([]byte, buflen)
} else {
return nil, errno
}
}
if ret == nil {
return nil, nil
}
return &Group{
Name: C.GoString(ret.gr_name),
Passwd: C.GoString(ret.gr_passwd),
Gid: Gid(ret.gr_gid),
Mem: strary(ret.gr_mem),
}, nil
}
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