func lookupUnix(gid int, groupname string, lookupByName bool) (*Group, error) {
var grp C.struct_group
var result *C.struct_group
var bufSize C.long
if runtime.GOOS == "freebsd" {
panic("Don't know how to deal with freebsd.")
} else {
bufSize = C.sysconf(C._SC_GETGR_R_SIZE_MAX) * 20
if bufSize <= 0 || bufSize > 1<<20 {
return nil, fmt.Errorf("group: unreasonable _SC_GETGR_R_SIZE_MAX of %d", bufSize)
}
}
buf := C.malloc(C.size_t(bufSize))
defer C.free(buf)
var rv C.int
if lookupByName {
nameC := C.CString(groupname)
defer C.free(unsafe.Pointer(nameC))
rv = C.mygetgrnam_r(nameC,
&grp,
(*C.char)(buf),
C.size_t(bufSize),
&result)
if rv != 0 {
return nil, fmt.Errorf("group: lookup groupname %s: %s", groupname, syscall.Errno(rv))
}
if result == nil {
return nil, UnknownGroupError(groupname)
}
} else {
rv = C.mygetgrgid_r(C.int(gid),
&grp,
(*C.char)(buf),
C.size_t(bufSize),
&result)
if rv != 0 {
return nil, fmt.Errorf("group: lookup groupid %d: %s", gid, syscall.Errno(rv))
}
if result == nil {
return nil, UnknownGroupIdError(gid)
}
}
u := &Group{
Gid: strconv.Itoa(int(grp.gr_gid)),
Groupname: C.GoString(grp.gr_name),
}
return u, nil
}
func getGroupId(group string) (int, error) {
var rv C.int
var grp C.struct_group
var grpres *C.struct_group
var bufSize C.long
var result int
bufSize = 1024
buf := C.malloc(C.size_t(bufSize))
defer C.free(buf)
rv = C.mygetgrnam_r(C.CString(group), &grp, (*C.char)(buf), C.size_t(bufSize), &grpres)
if rv != 0 {
return -1, errors.New("Could not read groupid")
}
if grpres != nil {
result = int(C.int(grp.gr_gid))
} else {
return -1, errors.New("Could not convert groupid")
}
return result, nil
}
func lookupGroup(groupname string) (*Group, error) {
var grp C.struct_group
var result *C.struct_group
buf := alloc(groupBuffer)
defer buf.free()
cname := C.CString(groupname)
defer C.free(unsafe.Pointer(cname))
err := retryWithBuffer(buf, func() syscall.Errno {
return syscall.Errno(C.mygetgrnam_r(cname,
&grp,
(*C.char)(buf.ptr),
C.size_t(buf.size),
&result))
})
if err != nil {
return nil, fmt.Errorf("user: lookup groupname %s: %v", groupname, err)
}
if result == nil {
return nil, UnknownGroupError(groupname)
}
return buildGroup(&grp), nil
}