move contents of taskchampion repo to tc/

rust/lib/src/uuid.rs

@@ -0,0 +1,176 @@
+use crate::traits::*;
+use crate::types::*;
+use libc;
+use taskchampion::Uuid;
+
+// 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;
+
+/// 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 TCUuid {
+    type RustType = Uuid;
+
+    unsafe fn from_ctype(self) -> Self::RustType {
+        // SAFETY:
+        //  - any 16-byte value is a valid Uuid
+        Uuid::from_bytes(self.0)
+    }
+
+    fn as_ctype(arg: Uuid) -> Self {
+        TCUuid(*arg.as_bytes())
+    }
+}
+
+/// Create a new, randomly-generated UUID.
+#[no_mangle]
+pub unsafe extern "C" fn tc_uuid_new_v4() -> TCUuid {
+    // SAFETY:
+    // - value is not allocated
+    unsafe { TCUuid::return_val(Uuid::new_v4()) }
+}
+
+/// Create a new UUID with the nil value.
+#[no_mangle]
+pub unsafe extern "C" fn tc_uuid_nil() -> TCUuid {
+    // SAFETY:
+    // - value is not allocated
+    unsafe { TCUuid::return_val(Uuid::nil()) }
+}
+
+/// TCUuidList represents a list of uuids.
+///
+/// The content of this struct must be treated as read-only.
+#[repr(C)]
+pub struct TCUuidList {
+    /// number of uuids in items
+    len: libc::size_t,
+
+    /// total size of items (internal use only)
+    _capacity: libc::size_t,
+
+    /// array of uuids. these remain owned by the TCUuidList instance and will be freed by
+    /// tc_uuid_list_free.  This pointer is never NULL for a valid TCUuidList.
+    items: *mut TCUuid,
+}
+
+impl CList for TCUuidList {
+    type Element = TCUuid;
+
+    unsafe fn from_raw_parts(items: *mut Self::Element, len: usize, cap: usize) -> Self {
+        TCUuidList {
+            len,
+            _capacity: cap,
+            items,
+        }
+    }
+
+    fn slice(&mut self) -> &mut [Self::Element] {
+        // SAFETY:
+        //  - because we have &mut self, we have read/write access to items[0..len]
+        //  - all items are properly initialized Element's
+        //  - return value lifetime is equal to &mmut self's, so access is exclusive
+        //  - items and len came from Vec, so total size is < isize::MAX
+        unsafe { std::slice::from_raw_parts_mut(self.items, self.len) }
+    }
+
+    fn into_raw_parts(self) -> (*mut Self::Element, usize, usize) {
+        (self.items, self.len, self._capacity)
+    }
+}
+
+/// 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 unsafe extern "C" fn tc_uuid_to_buf(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: &mut [u8] =
+        unsafe { std::slice::from_raw_parts_mut(buf as *mut u8, TC_UUID_STRING_BYTES) };
+    // SAFETY:
+    //  - tcuuid is a valid TCUuid (all byte patterns are valid)
+    let uuid: Uuid = unsafe { TCUuid::val_from_arg(tcuuid) };
+    uuid.to_hyphenated().encode_lower(buf);
+}
+
+/// Return the hyphenated string representation of a TCUuid.  The returned string
+/// must be freed with tc_string_free.
+#[no_mangle]
+pub unsafe extern "C" fn tc_uuid_to_str(tcuuid: TCUuid) -> TCString {
+    // SAFETY:
+    //  - tcuuid is a valid TCUuid (all byte patterns are valid)
+    let uuid: Uuid = unsafe { TCUuid::val_from_arg(tcuuid) };
+    let s = uuid.to_string();
+    // SAFETY:
+    //  - caller promises to free this value.
+    unsafe { TCString::return_val(s.into()) }
+}
+
+/// Parse the given string as a UUID.  Returns TC_RESULT_ERROR on parse failure or if the given
+/// string is not valid.
+#[no_mangle]
+pub unsafe extern "C" fn tc_uuid_from_str(s: TCString, uuid_out: *mut TCUuid) -> TCResult {
+    debug_assert!(!s.is_null());
+    debug_assert!(!uuid_out.is_null());
+    // SAFETY:
+    //  - s is valid (promised by caller)
+    //  - caller will not use s after this call (convention)
+    let mut s = unsafe { TCString::val_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 { TCUuid::val_to_arg_out(u, uuid_out) };
+            return TCResult::Ok;
+        }
+    }
+    TCResult::Error
+}
+
+/// Free a TCUuidList instance.  The instance, and all TCUuids it contains, must not be used after
+/// this call.
+///
+/// When this call returns, the `items` pointer will be NULL, signalling an invalid TCUuidList.
+#[no_mangle]
+pub unsafe extern "C" fn tc_uuid_list_free(tcuuids: *mut TCUuidList) {
+    // SAFETY:
+    //  - tcuuids is not NULL and points to a valid TCUuidList (caller is not allowed to
+    //    modify the list)
+    //  - caller promises not to use the value after return
+    unsafe { drop_value_list(tcuuids) };
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn empty_list_has_non_null_pointer() {
+        let tcuuids = unsafe { TCUuidList::return_val(Vec::new()) };
+        assert!(!tcuuids.items.is_null());
+        assert_eq!(tcuuids.len, 0);
+        assert_eq!(tcuuids._capacity, 0);
+    }
+
+    #[test]
+    fn free_sets_null_pointer() {
+        let mut tcuuids = unsafe { TCUuidList::return_val(Vec::new()) };
+        // SAFETY: testing expected behavior
+        unsafe { tc_uuid_list_free(&mut tcuuids) };
+        assert!(tcuuids.items.is_null());
+        assert_eq!(tcuuids.len, 0);
+        assert_eq!(tcuuids._capacity, 0);
+    }
+}