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diff --git a/storage/rust/src/lib.rs b/storage/rust/src/lib.rs
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! A Rust wrapper for mozStorage.
+//!
+//! mozStorage wraps the SQLite C API with support for XPCOM data structures,
+//! asynchronous statement execution, cleanup on shutdown, and connection
+//! cloning that propagates attached databases, pragmas, functions, and
+//! temporary entities. It also collects timing and memory usage stats for
+//! telemetry, and supports detailed statement logging. Additionally, mozStorage
+//! makes it possible to use the same connection handle from JS and native
+//! (C++ and Rust) code.
+//!
+//! Most mozStorage objects, like connections, statements, result rows,
+//! and variants, are thread-safe. Each connection manages a background
+//! thread that can be used to execute statements asynchronously, without
+//! blocking the main thread.
+//!
+//! This crate provides a thin wrapper to make mozStorage easier to use
+//! from Rust. It only wraps the synchronous API, so you can either manage
+//! the entire connection from a background thread, or use the `moz_task`
+//! crate to dispatch tasks to the connection's async thread. Executing
+//! synchronous statements on the main thread is not supported, and will
+//! assert in debug builds.
+
+#![allow(non_snake_case)]
+
+use std::{borrow::Cow, convert::TryFrom, error, fmt, ops::Deref, result};
+
+use nserror::{nsresult, NS_ERROR_NO_INTERFACE, NS_ERROR_UNEXPECTED};
+use nsstring::nsCString;
+use storage_variant::VariantType;
+use xpcom::{
+    getter_addrefs,
+    interfaces::{
+        mozIStorageAsyncConnection, mozIStorageConnection, mozIStorageStatement, nsIEventTarget,
+        nsIThread,
+    },
+    RefPtr, XpCom,
+};
+
+const SQLITE_OK: i32 = 0;
+
+pub type Result<T> = result::Result<T, Error>;
+
+/// `Conn` wraps a `mozIStorageConnection`.
+#[derive(Clone)]
+pub struct Conn {
+    handle: RefPtr<mozIStorageConnection>,
+}
+
+// This is safe as long as our `mozIStorageConnection` is an instance of
+// `mozilla::storage::Connection`, which is atomically reference counted.
+unsafe impl Send for Conn {}
+unsafe impl Sync for Conn {}
+
+impl Conn {
+    /// Wraps a `mozIStorageConnection` in a `Conn`.
+    #[inline]
+    pub fn wrap(connection: RefPtr<mozIStorageConnection>) -> Conn {
+        Conn { handle: connection }
+    }
+
+    /// Returns the wrapped `mozIStorageConnection`.
+    #[inline]
+    pub fn connection(&self) -> &mozIStorageConnection {
+        &self.handle
+    }
+
+    /// Returns the maximum number of bound parameters for statements executed
+    /// on this connection.
+    pub fn variable_limit(&self) -> Result<usize> {
+        let mut limit = 0i32;
+        let rv = unsafe { self.handle.GetVariableLimit(&mut limit) };
+        if rv.failed() {
+            return Err(Error::Limit);
+        }
+        usize::try_from(limit).map_err(|_| Error::Limit)
+    }
+
+    /// Returns the async thread for this connection. This can be used
+    /// with `moz_task` to run synchronous statements on the storage
+    /// thread, without blocking the main thread.
+    pub fn thread(&self) -> Result<RefPtr<nsIThread>> {
+        let target = self.handle.get_interface::<nsIEventTarget>();
+        target
+            .and_then(|t| t.query_interface::<nsIThread>())
+            .ok_or(Error::NoThread)
+    }
+
+    /// Prepares a SQL statement. `query` should only contain one SQL statement.
+    /// If `query` contains multiple statements, only the first will be prepared,
+    /// and the rest will be ignored.
+    pub fn prepare<Q: AsRef<str>>(&self, query: Q) -> Result<Statement> {
+        let statement = self.call_and_wrap_error(DatabaseOp::Prepare, || {
+            getter_addrefs(|p| unsafe {
+                self.handle
+                    .CreateStatement(&*nsCString::from(query.as_ref()), p)
+            })
+        })?;
+        Ok(Statement {
+            conn: self,
+            handle: statement,
+        })
+    }
+
+    /// Executes a SQL statement. `query` may contain one or more
+    /// semicolon-separated SQL statements.
+    pub fn exec<Q: AsRef<str>>(&self, query: Q) -> Result<()> {
+        self.call_and_wrap_error(DatabaseOp::Exec, || {
+            unsafe {
+                self.handle
+                    .ExecuteSimpleSQL(&*nsCString::from(query.as_ref()))
+            }
+            .to_result()
+        })
+    }
+
+    /// Opens a transaction with the default transaction behavior for this
+    /// connection. The transaction should be committed when done. Uncommitted
+    /// `Transaction`s will automatically roll back when they go out of scope.
+    pub fn transaction(&mut self) -> Result<Transaction> {
+        let behavior = self.get_default_transaction_behavior();
+        Transaction::new(self, behavior)
+    }
+
+    /// Indicates if a transaction is currently open on this connection.
+    /// Attempting to open a new transaction when one is already in progress
+    /// will fail with a "cannot start a transaction within a transaction"
+    /// error.
+    ///
+    /// Note that this is `true` even if the transaction was started by another
+    /// caller, like `Sqlite.sys.mjs` or `mozStorageTransaction` from C++. See the
+    /// explanation above `mozIStorageConnection.transactionInProgress` for why
+    /// this matters.
+    pub fn transaction_in_progress(&self) -> Result<bool> {
+        let mut in_progress = false;
+        unsafe { self.handle.GetTransactionInProgress(&mut in_progress) }.to_result()?;
+        Ok(in_progress)
+    }
+
+    /// Opens a transaction with the requested behavior.
+    pub fn transaction_with_behavior(
+        &mut self,
+        behavior: TransactionBehavior,
+    ) -> Result<Transaction> {
+        Transaction::new(self, behavior)
+    }
+
+    fn get_default_transaction_behavior(&self) -> TransactionBehavior {
+        let mut typ = 0i32;
+        let rv = unsafe { self.handle.GetDefaultTransactionType(&mut typ) };
+        if rv.failed() {
+            return TransactionBehavior::Deferred;
+        }
+        match typ {
+            mozIStorageAsyncConnection::TRANSACTION_IMMEDIATE => TransactionBehavior::Immediate,
+            mozIStorageAsyncConnection::TRANSACTION_EXCLUSIVE => TransactionBehavior::Exclusive,
+            _ => TransactionBehavior::Deferred,
+        }
+    }
+
+    /// Invokes a storage operation and returns the last SQLite error if the
+    /// operation fails. This lets `Conn::{prepare, exec}` and
+    /// `Statement::{step, execute}` return more detailed errors, as the
+    /// `nsresult` codes that mozStorage uses are often too generic. For
+    /// example, `NS_ERROR_FAILURE` might be anything from a SQL syntax error
+    /// to an invalid column name in a trigger.
+    ///
+    /// Note that the last error may not be accurate if the underlying
+    /// `mozIStorageConnection` is used concurrently from multiple threads.
+    /// Multithreaded callers that share a connection should serialize their
+    /// uses.
+    fn call_and_wrap_error<T>(
+        &self,
+        op: DatabaseOp,
+        func: impl FnOnce() -> result::Result<T, nsresult>,
+    ) -> Result<T> {
+        func().or_else(|rv| -> Result<T> {
+            let mut code = 0i32;
+            unsafe { self.handle.GetLastError(&mut code) }.to_result()?;
+            Err(if code != SQLITE_OK {
+                let mut message = nsCString::new();
+                unsafe { self.handle.GetLastErrorString(&mut *message) }.to_result()?;
+                Error::Database {
+                    rv,
+                    op,
+                    code,
+                    message,
+                }
+            } else {
+                rv.into()
+            })
+        })
+    }
+}
+
+pub enum TransactionBehavior {
+    Deferred,
+    Immediate,
+    Exclusive,
+}
+
+pub struct Transaction<'c> {
+    conn: &'c mut Conn,
+    active: bool,
+}
+
+impl<'c> Transaction<'c> {
+    /// Opens a transaction on `conn` with the given `behavior`.
+    fn new(conn: &'c mut Conn, behavior: TransactionBehavior) -> Result<Transaction<'c>> {
+        conn.exec(match behavior {
+            TransactionBehavior::Deferred => "BEGIN DEFERRED",
+            TransactionBehavior::Immediate => "BEGIN IMMEDIATE",
+            TransactionBehavior::Exclusive => "BEGIN EXCLUSIVE",
+        })?;
+        Ok(Transaction { conn, active: true })
+    }
+
+    /// Commits the transaction.
+    pub fn commit(mut self) -> Result<()> {
+        if self.active {
+            self.conn.exec("COMMIT")?;
+            self.active = false;
+        }
+        Ok(())
+    }
+
+    /// Rolls the transaction back.
+    pub fn rollback(mut self) -> Result<()> {
+        self.abort()
+    }
+
+    fn abort(&mut self) -> Result<()> {
+        if self.active {
+            self.conn.exec("ROLLBACK")?;
+            self.active = false;
+        }
+        Ok(())
+    }
+}
+
+impl<'c> Deref for Transaction<'c> {
+    type Target = Conn;
+
+    fn deref(&self) -> &Conn {
+        self.conn
+    }
+}
+
+impl<'c> Drop for Transaction<'c> {
+    fn drop(&mut self) {
+        let _ = self.abort();
+    }
+}
+
+pub struct Statement<'c> {
+    conn: &'c Conn,
+    handle: RefPtr<mozIStorageStatement>,
+}
+
+impl<'c> Statement<'c> {
+    /// Binds a parameter at the given `index` to the prepared statement.
+    /// `value` is any type that can be converted into a `Variant`.
+    pub fn bind_by_index<V: VariantType>(&mut self, index: u32, value: V) -> Result<()> {
+        let variant = value.into_variant();
+        unsafe { self.handle.BindByIndex(index as u32, variant.coerce()) }
+            .to_result()
+            .map_err(|rv| Error::BindByIndex {
+                rv,
+                data_type: V::type_name(),
+                index,
+            })
+    }
+
+    /// Binds a parameter with the given `name` to the prepared statement.
+    pub fn bind_by_name<N: AsRef<str>, V: VariantType>(&mut self, name: N, value: V) -> Result<()> {
+        let name = name.as_ref();
+        let variant = value.into_variant();
+        unsafe {
+            self.handle
+                .BindByName(&*nsCString::from(name), variant.coerce())
+        }
+        .to_result()
+        .map_err(|rv| Error::BindByName {
+            rv,
+            data_type: V::type_name(),
+            name: name.into(),
+        })
+    }
+
+    /// Executes the statement and returns the next row of data.
+    pub fn step<'s>(&'s mut self) -> Result<Option<Step<'c, 's>>> {
+        let has_more = self.conn.call_and_wrap_error(DatabaseOp::Step, || {
+            let mut has_more = false;
+            unsafe { self.handle.ExecuteStep(&mut has_more) }.to_result()?;
+            Ok(has_more)
+        })?;
+        Ok(if has_more { Some(Step(self)) } else { None })
+    }
+
+    /// Executes the statement once, discards any data, and resets the
+    /// statement.
+    pub fn execute(&mut self) -> Result<()> {
+        self.conn.call_and_wrap_error(DatabaseOp::Execute, || {
+            unsafe { self.handle.Execute() }.to_result()
+        })
+    }
+
+    /// Resets the prepared statement so that it's ready to be executed
+    /// again, and clears any bound parameters.
+    pub fn reset(&mut self) -> Result<()> {
+        unsafe { self.handle.Reset() }.to_result()?;
+        Ok(())
+    }
+
+    fn get_column_index(&self, name: &str) -> Result<u32> {
+        let mut index = 0u32;
+        let rv = unsafe {
+            self.handle
+                .GetColumnIndex(&*nsCString::from(name), &mut index)
+        };
+        if rv.succeeded() {
+            Ok(index)
+        } else {
+            Err(Error::InvalidColumn {
+                rv,
+                name: name.into(),
+            })
+        }
+    }
+
+    fn get_column_value<T: VariantType>(&self, index: u32) -> result::Result<T, nsresult> {
+        let variant = getter_addrefs(|p| unsafe { self.handle.GetVariant(index, p) })?;
+        let value = T::from_variant(variant.coerce())?;
+        Ok(value)
+    }
+}
+
+impl<'c> Drop for Statement<'c> {
+    fn drop(&mut self) {
+        unsafe { self.handle.Finalize() };
+    }
+}
+
+/// A step is the next row in the result set for a statement.
+pub struct Step<'c, 's>(&'s mut Statement<'c>);
+
+impl<'c, 's> Step<'c, 's> {
+    /// Returns the value of the column at `index` for the current row.
+    pub fn get_by_index<T: VariantType>(&self, index: u32) -> Result<T> {
+        self.0
+            .get_column_value(index)
+            .map_err(|rv| Error::GetByIndex {
+                rv,
+                data_type: T::type_name(),
+                index,
+            })
+    }
+
+    /// A convenience wrapper that returns the default value for the column
+    /// at `index` if `NULL`.
+    pub fn get_by_index_or_default<T: VariantType + Default>(&self, index: u32) -> T {
+        self.get_by_index(index).unwrap_or_default()
+    }
+
+    /// Returns the value of the column specified by `name` for the current row.
+    pub fn get_by_name<N: AsRef<str>, T: VariantType>(&self, name: N) -> Result<T> {
+        let name = name.as_ref();
+        let index = self.0.get_column_index(name)?;
+        self.0
+            .get_column_value(index)
+            .map_err(|rv| Error::GetByName {
+                rv,
+                data_type: T::type_name(),
+                name: name.into(),
+            })
+    }
+
+    /// Returns the default value for the column with the given `name`, or the
+    /// default if the column is `NULL`.
+    pub fn get_by_name_or_default<N: AsRef<str>, T: VariantType + Default>(&self, name: N) -> T {
+        self.get_by_name(name).unwrap_or_default()
+    }
+}
+
+/// A database operation, included for better context in error messages.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum DatabaseOp {
+    Exec,
+    Prepare,
+    Step,
+    Execute,
+}
+
+impl DatabaseOp {
+    /// Returns a description of the operation to include in an error message.
+    pub fn what(&self) -> &'static str {
+        match self {
+            DatabaseOp::Exec => "execute SQL string",
+            DatabaseOp::Prepare => "prepare statement",
+            DatabaseOp::Step => "step statement",
+            DatabaseOp::Execute => "execute statement",
+        }
+    }
+}
+
+/// Storage errors.
+#[derive(Debug)]
+pub enum Error {
+    /// A connection doesn't have a usable async thread. The connection might be
+    /// closed, or the thread manager may have shut down.
+    NoThread,
+
+    /// Failed to get a limit for a database connection.
+    Limit,
+
+    /// A database operation failed. The error includes a SQLite result code,
+    /// and an explanation string.
+    Database {
+        rv: nsresult,
+        op: DatabaseOp,
+        code: i32,
+        message: nsCString,
+    },
+
+    /// A parameter with the given data type couldn't be bound at this index,
+    /// likely because the index is out of range.
+    BindByIndex {
+        rv: nsresult,
+        data_type: Cow<'static, str>,
+        index: u32,
+    },
+
+    /// A parameter with the given type couldn't be bound to this name, likely
+    /// because the statement doesn't have a matching `:`-prefixed parameter
+    /// with the name.
+    BindByName {
+        rv: nsresult,
+        data_type: Cow<'static, str>,
+        name: String,
+    },
+
+    /// A column with this name doesn't exist.
+    InvalidColumn { rv: nsresult, name: String },
+
+    /// A value of the given type couldn't be accessed at this index. This is
+    /// the error returned when a type conversion fails; for example, requesting
+    /// an `nsString` instead of an `Option<nsString>` when the column is `NULL`.
+    GetByIndex {
+        rv: nsresult,
+        data_type: Cow<'static, str>,
+        index: u32,
+    },
+
+    /// A value of the given type couldn't be accessed for the column with
+    /// this name.
+    GetByName {
+        rv: nsresult,
+        data_type: Cow<'static, str>,
+        name: String,
+    },
+
+    /// A storage operation failed for other reasons.
+    Other(nsresult),
+}
+
+impl error::Error for Error {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        None
+    }
+}
+
+impl From<nsresult> for Error {
+    fn from(rv: nsresult) -> Error {
+        Error::Other(rv)
+    }
+}
+
+impl From<Error> for nsresult {
+    fn from(err: Error) -> nsresult {
+        match err {
+            Error::NoThread => NS_ERROR_NO_INTERFACE,
+            Error::Limit => NS_ERROR_UNEXPECTED,
+            Error::Database { rv, .. }
+            | Error::BindByIndex { rv, .. }
+            | Error::BindByName { rv, .. }
+            | Error::InvalidColumn { rv, .. }
+            | Error::GetByIndex { rv, .. }
+            | Error::GetByName { rv, .. }
+            | Error::Other(rv) => rv,
+        }
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Error::NoThread => f.write_str("Async thread unavailable for storage connection"),
+            Error::Limit => f.write_str("Failed to get limit for storage connection"),
+            Error::Database {
+                op, code, message, ..
+            } => {
+                if message.is_empty() {
+                    write!(f, "Failed to {} with code {}", op.what(), code)
+                } else {
+                    write!(
+                        f,
+                        "Failed to {} with code {} ({})",
+                        op.what(),
+                        code,
+                        message
+                    )
+                }
+            }
+            Error::BindByIndex {
+                data_type, index, ..
+            } => write!(f, "Can't bind {} at {}", data_type, index),
+            Error::BindByName {
+                data_type, name, ..
+            } => write!(f, "Can't bind {} to named parameter {}", data_type, name),
+            Error::InvalidColumn { name, .. } => write!(f, "Column {} doesn't exist", name),
+            Error::GetByIndex {
+                data_type, index, ..
+            } => write!(f, "Can't get {} at {}", data_type, index),
+            Error::GetByName {
+                data_type, name, ..
+            } => write!(f, "Can't get {} for column {}", data_type, name),
+            Error::Other(rv) => write!(f, "Storage operation failed with {}", rv.error_name()),
+        }
+    }
+}