Trusty: provenance library workspace (initial import)

crates/adapters/trusty-policy-postgres/examples/emit_ddl.rs

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+//! Print the permission model's schema as a plain `.sql` migration.
+//!
+//! A consumer whose migrations are files rather than a Rust `open()`
+//! call — Supabase, sqlx, plain psql — needs the same DDL as text.
+//! Emitting it from the same constants the library applies is the point:
+//! two hand-maintained copies of an authorisation schema will diverge,
+//! and the divergence will be discovered by something going wrong.
+//!
+//! ```text
+//! cargo run -p trusty-policy-postgres --example emit_ddl > 0001_permission_model.sql
+//! ```
+//!
+//! Pass a table and its scope column to additionally emit the policies
+//! that put that table under enforcement:
+//!
+//! ```text
+//! cargo run -p trusty-policy-postgres --example emit_ddl -- public.calendar resource_scope
+//! ```
+
+use trusty_policy_postgres::permits::DDL_FUNCTIONS;
+use trusty_policy_postgres::schema::{DDL_SCHEMA_VERSION_UPSERT, DDL_V1, SCHEMA_VERSION};
+use trusty_policy_postgres::store::policy_statements;
+
+fn main() {
+    println!("-- Generated by `cargo run -p trusty-policy-postgres --example emit_ddl`.");
+    println!("-- Source of truth is trusty-policy-postgres; edit there, regenerate here.");
+    println!("-- Applying this by hand and by GrantStore::open must agree, so do not");
+    println!("-- edit this file directly.");
+    println!();
+
+    for stmt in DDL_V1 {
+        println!("{};", stmt.trim());
+        println!();
+    }
+
+    for stmt in DDL_FUNCTIONS {
+        println!("{};", stmt.trim());
+        println!();
+    }
+
+    // The library upserts this with a bind parameter; a file has no
+    // parameters, so the version is inlined. It is a constant, not
+    // input.
+    println!(
+        "{};",
+        DDL_SCHEMA_VERSION_UPSERT
+            .trim()
+            .replace("$1", &format!("'{SCHEMA_VERSION}'"))
+    );
+    println!();
+
+    let args: Vec<String> = std::env::args().skip(1).collect();
+    match args.as_slice() {
+        [] => {
+            println!("-- No table given, so no policies were emitted.");
+            println!("-- Installing this schema protects nothing on its own: a table is");
+            println!("-- guarded only once it has ENABLE + FORCE ROW LEVEL SECURITY and the");
+            println!("-- four policies. Re-run with a table and its scope column, e.g.");
+            println!("--   ... --example emit_ddl -- public.calendar resource_scope");
+        }
+        [table, column] => match policy_statements(table, column) {
+            Ok(stmts) => {
+                println!("-- Enforcement for {table}({column}).");
+                for stmt in stmts {
+                    println!("{stmt}");
+                }
+            }
+            Err(e) => {
+                eprintln!("error: {e}");
+                std::process::exit(1);
+            }
+        },
+        _ => {
+            eprintln!("usage: emit_ddl [<schema.table> <scope_column>]");
+            std::process::exit(2);
+        }
+    }
+}