Use CStr and CString because BorrowDatum is not impled for str

Author: workingjubilee

pgrx-tests/src/tests/borrow_datum.rs

@@ -60,6 +60,7 @@ mod tests {
     use super::*;
     #[allow(unused)]
     use crate as pgrx_tests;
+    use std::ffi::{CStr, CString};
 
     // Exercising BorrowDatum impls
     clonetrip!(clone_bool, test_clone_bool, &'a bool, &false);
@@ -73,7 +74,7 @@ mod tests {
         &'a pg_sys::Point,
         &pg_sys::Point { x: -1.0, y: f64::INFINITY }
     );
-    clonetrip!(clone_str, test_clone_str, &'a str => String, "string", String::from("string"));
+    clonetrip!(clone_str, test_clone_str, &'a CStr => CString, c"cee string", CString::from(c"cee string"));
     clonetrip!(
         clone_oid,
         test_clone_oid,

pgrx/src/datum/from.rs

@@ -12,6 +12,7 @@
 use crate::{
     pg_sys, varlena, varlena_to_byte_slice, AllocatedByPostgres, IntoDatum, PgBox, PgMemoryContexts,
 };
+use alloc::ffi::CString;
 use core::{ffi::CStr, mem::size_of};
 use std::num::NonZeroUsize;
 
@@ -482,6 +483,33 @@ impl<'a> FromDatum for &'a core::ffi::CStr {
     }
 }
 
+impl FromDatum for alloc::ffi::CString {
+    #[inline]
+    unsafe fn from_polymorphic_datum(
+        datum: pg_sys::Datum,
+        is_null: bool,
+        _: pg_sys::Oid,
+    ) -> Option<CString> {
+        if is_null || datum.is_null() {
+            None
+        } else {
+            Some(core::ffi::CStr::from_ptr(datum.cast_mut_ptr()).to_owned())
+        }
+    }
+
+    unsafe fn from_datum_in_memory_context(
+        _memory_context: PgMemoryContexts,
+        datum: pg_sys::Datum,
+        is_null: bool,
+        _typoid: pg_sys::Oid,
+    ) -> Option<Self>
+    where
+        Self: Sized,
+    {
+        Self::from_polymorphic_datum(datum, is_null, _typoid)
+    }
+}
+
 /// for bytea
 impl<'a> FromDatum for &'a [u8] {
     #[inline]