func lookupUser(username string) (*User, error) {
var pwd C.struct_passwd
var result *C.struct_passwd
nameC := C.CString(username)
defer C.free(unsafe.Pointer(nameC))
buf := alloc(userBuffer)
defer buf.free()
err := retryWithBuffer(buf, func() syscall.Errno {
// mygetpwnam_r is a wrapper around getpwnam_r to avoid
// passing a size_t to getpwnam_r, because for unknown
// reasons passing a size_t to getpwnam_r doesn't work on
// Solaris.
return syscall.Errno(C.mygetpwnam_r(nameC,
&pwd,
(*C.char)(buf.ptr),
C.size_t(buf.size),
&result))
})
if err != nil {
return nil, fmt.Errorf("user: lookup username %s: %v", username, err)
}
if result == nil {
return nil, UnknownUserError(username)
}
return buildUser(&pwd), err
}
func lookupUnix(uid int, username string, lookupByName bool) (*User, error) {
var pwd C.struct_passwd
var result *C.struct_passwd
bufSize := C.sysconf(C._SC_GETPW_R_SIZE_MAX)
if bufSize == -1 {
// DragonFly and FreeBSD do not have _SC_GETPW_R_SIZE_MAX.
// Additionally, not all Linux systems have it, either. For
// example, the musl libc returns -1.
bufSize = 1024
}
if bufSize <= 0 || bufSize > 1<<20 {
return nil, fmt.Errorf("user: unreasonable _SC_GETPW_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(username)
defer C.free(unsafe.Pointer(nameC))
// mygetpwnam_r is a wrapper around getpwnam_r to avoid
// passing a size_t to getpwnam_r, because for unknown
// reasons passing a size_t to getpwnam_r doesn't work on
// Solaris.
rv = C.mygetpwnam_r(nameC,
&pwd,
(*C.char)(buf),
C.size_t(bufSize),
&result)
if rv != 0 {
return nil, fmt.Errorf("user: lookup username %s: %s", username, syscall.Errno(rv))
}
if result == nil {
return nil, UnknownUserError(username)
}
} else {
// mygetpwuid_r is a wrapper around getpwuid_r to
// to avoid using uid_t because C.uid_t(uid) for
// unknown reasons doesn't work on linux.
rv = C.mygetpwuid_r(C.int(uid),
&pwd,
(*C.char)(buf),
C.size_t(bufSize),
&result)
if rv != 0 {
return nil, fmt.Errorf("user: lookup userid %d: %s", uid, syscall.Errno(rv))
}
if result == nil {
return nil, UnknownUserIdError(uid)
}
}
u := &User{
Uid: strconv.Itoa(int(pwd.pw_uid)),
Gid: strconv.Itoa(int(pwd.pw_gid)),
Username: C.GoString(pwd.pw_name),
Name: C.GoString(pwd.pw_gecos),
HomeDir: C.GoString(pwd.pw_dir),
}
// The pw_gecos field isn't quite standardized. Some docs
// say: "It is expected to be a comma separated list of
// personal data where the first item is the full name of the
// user."
if i := strings.Index(u.Name, ","); i >= 0 {
u.Name = u.Name[:i]
}
return u, nil
}