schema: guard property string constraint checking

StringSchema::check_constraint runs `parse_property_string` for
property strings, but when we deserialize a `PropertyString` we
immediately follow that up with deserializing it using the schema, so
there's no need to check it beforehand.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

proxmox-schema/src/de/mod.rs

@@ -1,6 +1,7 @@
 //! Property string deserialization.
 
 use std::borrow::Cow;
+use std::cell::Cell;
 use std::fmt;
 use std::ops::Range;
 
@@ -18,6 +19,25 @@ pub use extract::ExtractValueDeserializer;
 
 use cow3::{str_slice_to_range, Cow3};
 
+// Used to disable calling `check_constraints` on a `StringSchema` if it is being deserialized
+// for a `PropertyString`, which performs its own checking.
+thread_local! {
+    static IN_PROPERTY_STRING: Cell<bool> = Cell::new(false);
+}
+
+pub(crate) struct InPropertyStringGuard;
+
+pub(crate) fn set_in_property_string() -> InPropertyStringGuard {
+    IN_PROPERTY_STRING.with(|v| v.set(true));
+    InPropertyStringGuard
+}
+
+impl Drop for InPropertyStringGuard {
+    fn drop(&mut self) {
+        IN_PROPERTY_STRING.with(|v| v.set(false));
+    }
+}
+
 #[derive(Debug)]
 pub struct Error(Cow<'static, str>);
 
@@ -86,9 +106,11 @@ impl<'de, 'i> SchemaDeserializer<'de, 'i> {
     where
         V: de::Visitor<'de>,
     {
-        schema
-            .check_constraints(&self.input)
-            .map_err(|err| Error::invalid(err))?;
+        if !IN_PROPERTY_STRING.with(|v| v.get()) {
+            schema
+                .check_constraints(&self.input)
+                .map_err(|err| Error::invalid(err))?;
+        }
         match self.input {
             Cow3::Original(input) => visitor.visit_borrowed_str(input),
             Cow3::Intermediate(input) => visitor.visit_str(input),

proxmox-schema/src/property_string.rs

@@ -267,9 +267,11 @@ where
     where
         D: serde::Deserializer<'de>,
     {
+        use crate::de::{set_in_property_string, InPropertyStringGuard};
+
         use std::marker::PhantomData;
 
-        struct V<T>(PhantomData<T>);
+        struct V<T>(InPropertyStringGuard, PhantomData<T>);
 
         impl<'de, T> serde::de::Visitor<'de> for V<T>
         where
@@ -292,6 +294,7 @@ where
             where
                 E: serde::de::Error,
             {
+                drop(self); // unset IN_PROPERTY_STRING
                 T::deserialize(crate::de::SchemaDeserializer::new(s, &T::API_SCHEMA))
                     .map_err(|err| E::custom(err.to_string()))
             }
@@ -300,12 +303,15 @@ where
             where
                 E: serde::de::Error,
             {
+                drop(self); // unset IN_PROPERTY_STRING
                 T::deserialize(crate::de::SchemaDeserializer::new(s, &T::API_SCHEMA))
                     .map_err(|err| E::custom(err.to_string()))
             }
         }
 
-        deserializer.deserialize_string(V(PhantomData)).map(Self)
+        deserializer
+            .deserialize_string(V(set_in_property_string(), PhantomData))
+            .map(Self)
     }
 }