Conditionally use getrandom().

Author: rkistner

Cargo.lock

@@ -33,4 +33,7 @@ features = []
 loadable_extension = ["sqlite_nostd/loadable_extension"]
 static = ["sqlite_nostd/static"]
 omit_load_extension = ["sqlite_nostd/omit_load_extension"]
+# Enable to use the getrandom crate instead of sqlite3_randomness
+# Enable for Windows builds; do not enable for WASM
+getrandom = ["uuid/v4"]
 

crates/core/Cargo.toml

@@ -85,6 +85,18 @@ pub fn deserialize_optional_string_to_i64<'de, D>(deserializer: D) -> Result<Opt
     }
 }
 
+// Use getrandom crate to generate UUID
+#[cfg(feature = "getrandom")]
+pub fn gen_uuid() -> Uuid {
+    let id = Uuid::new_v4();
+    id
+}
+
+// Default - use sqlite3_randomness to generate UUID
+// This uses ChaCha20 PRNG, with /dev/urandom as a seed on unix.
+// On Windows, it uses custom logic for the seed, which may not be secure.
+// Rather avoid this version for Windows builds.
+#[cfg(not(feature = "getrandom"))]
 pub fn gen_uuid() -> Uuid {
     let mut random_bytes: [u8; 16] = [0; 16];
     sqlite::randomness(&mut random_bytes);

crates/core/src/util.rs

@@ -13,7 +13,7 @@ powersync_core = { path="../core" }
 sqlite_nostd = { workspace=true }
 
 [features]
-default = ["powersync_core/static", "powersync_core/omit_load_extension", "sqlite_nostd/static", "sqlite_nostd/omit_load_extension"]
+default = ["powersync_core/static", "powersync_core/omit_load_extension", "powersync_core/getrandom", "sqlite_nostd/static", "sqlite_nostd/omit_load_extension"]
 
 [build-dependencies]
 cc = "1.0.46"

crates/shell/Cargo.toml

@@ -25,5 +25,4 @@ fn main() {
     cfg.compile("sqlite-ps");
 
     println!("cargo:rustc-link-lib=readline");
-    println!("cargo:rustc-link-lib=c");
 }