taskwarrior/lib/src/uuid.rs
2022-02-06 05:27:30 +00:00

93 lines
3.1 KiB
Rust

use crate::string::TCString;
use crate::traits::*;
use libc;
use taskchampion::Uuid;
/// TCUuid is used as a task identifier. Uuids do not contain any pointers and need not be freed.
/// Uuids are typically treated as opaque, but the bytes are available in big-endian format.
///
/// cbindgen:field-names=[bytes]
#[repr(C)]
pub struct TCUuid([u8; 16]);
impl PassByValue for Uuid {
type CType = TCUuid;
unsafe fn from_ctype(arg: TCUuid) -> Self {
// SAFETY:
// - any 16-byte value is a valid Uuid
Uuid::from_bytes(arg.0)
}
fn as_ctype(self) -> TCUuid {
TCUuid(*self.as_bytes())
}
}
/// Create a new, randomly-generated UUID.
#[no_mangle]
pub extern "C" fn tc_uuid_new_v4() -> TCUuid {
Uuid::new_v4().return_val()
}
/// Create a new UUID with the nil value.
#[no_mangle]
pub extern "C" fn tc_uuid_nil() -> TCUuid {
Uuid::nil().return_val()
}
// NOTE: this must be a simple constant so that cbindgen can evaluate it
/// Length, in bytes, of the string representation of a UUID (without NUL terminator)
pub const TC_UUID_STRING_BYTES: usize = 36;
/// Write the string representation of a TCUuid into the given buffer, which must be
/// at least TC_UUID_STRING_BYTES long. No NUL terminator is added.
#[no_mangle]
pub extern "C" fn tc_uuid_to_buf<'a>(tcuuid: TCUuid, buf: *mut libc::c_char) {
debug_assert!(!buf.is_null());
// SAFETY:
// - buf is valid for len bytes (by C convention)
// - (no alignment requirements for a byte slice)
// - content of buf will not be mutated during the lifetime of this slice (lifetime
// does not outlive this function call)
// - the length of the buffer is less than isize::MAX (promised by caller)
let buf: &'a mut [u8] = unsafe {
std::slice::from_raw_parts_mut(buf as *mut u8, ::uuid::adapter::Hyphenated::LENGTH)
};
// SAFETY:
// - tcuuid is a valid TCUuid (all byte patterns are valid)
let uuid: Uuid = unsafe { Uuid::from_arg(tcuuid) };
uuid.to_hyphenated().encode_lower(buf);
}
/// Write the string representation of a TCUuid into the given buffer, which must be
/// at least TC_UUID_STRING_BYTES long. No NUL terminator is added.
#[no_mangle]
pub extern "C" fn tc_uuid_to_str(tcuuid: TCUuid) -> *mut TCString<'static> {
// SAFETY:
// - tcuuid is a valid TCUuid (all byte patterns are valid)
let uuid: Uuid = unsafe { Uuid::from_arg(tcuuid) };
let s = uuid.to_string();
// SAFETY: see TCString docstring
unsafe { TCString::from(s).return_val() }
}
/// Parse the given string as a UUID. Returns false on failure.
#[no_mangle]
pub extern "C" fn tc_uuid_from_str<'a>(s: *mut TCString, uuid_out: *mut TCUuid) -> bool {
// TODO: TCResult instead
debug_assert!(!s.is_null());
debug_assert!(!uuid_out.is_null());
// SAFETY: see TCString docstring
let s = unsafe { TCString::take_from_arg(s) };
if let Ok(s) = s.as_str() {
if let Ok(u) = Uuid::parse_str(s) {
// SAFETY:
// - uuid_out is not NULL (promised by caller)
// - alignment is not required
unsafe { u.to_arg_out(uuid_out) };
return true;
}
}
false
}