document and check minimum SQLite version

Fixes #147

CHANGELOG.md

@@ -11,6 +11,8 @@ Each release is tagged in Git and on the Docker repository
 *   fix [#146](https://github.com/scottlamb/moonfire-nvr/issues/146): "init
     segment fetch error" when browsers have cached data from `v0.6.4` and
     before.
+*   fix [#147](https://github.com/scottlamb/moonfire-nvr/issues/147): confusing
+    `nvr init` failures when using very old versions of SQLite.
 
 ## `v0.6.5` (2021-08-13)
 

guide/build.md

@@ -177,7 +177,9 @@ To build the server, you will need the following C libraries installed:
     timeouts for RTSP. For reliable reconnections on error, it's strongly
     recommended to use ffmpeg library versions >= 55.1.101.
 
-*   [SQLite3](https://www.sqlite.org/).
+*   [SQLite3](https://www.sqlite.org/), at least version 3.14.0.
+    (You can skip this if you compile with `--features=bundled` and
+    don't mind the `moonfire-nvr sql` command not working.)
 
 *   [`ncursesw`](https://www.gnu.org/software/ncurses/), the UTF-8 version of
     the `ncurses` library.

server/db/db.rs

@@ -35,7 +35,7 @@ use crate::schema;
 use crate::signal;
 use base::clock::{self, Clocks};
 use base::strutil::encode_size;
-use failure::{bail, format_err, Error};
+use failure::{bail, format_err, Error, ResultExt};
 use fnv::{FnvHashMap, FnvHashSet};
 use hashlink::LinkedHashMap;
 use itertools::Itertools;
@@ -2117,13 +2117,27 @@ pub(crate) fn set_integrity_pragmas(conn: &mut rusqlite::Connection) -> Result<(
     Ok(())
 }
 
+pub(crate) fn check_sqlite_version() -> Result<(), Error> {
+    // SQLite version 3.14.0 introduced the "without rowid" syntax used in the schema.
+    // https://www.sqlite.org/vtab.html#worid
+    if rusqlite::version_number() < 3014000 {
+        bail!(
+            "SQLite version {} is too old; need at least 3.14.0",
+            rusqlite::version()
+        );
+    }
+    Ok(())
+}
+
 /// Initializes a database.
 /// Note this doesn't set journal options, so that it can be used on in-memory databases for
 /// test code.
 pub fn init(conn: &mut rusqlite::Connection) -> Result<(), Error> {
+    check_sqlite_version()?;
     set_integrity_pragmas(conn)?;
     let tx = conn.transaction()?;
-    tx.execute_batch(include_str!("schema.sql"))?;
+    tx.execute_batch(include_str!("schema.sql"))
+        .context("unable to create database schema")?;
     {
         let uuid = ::uuid::Uuid::new_v4();
         let uuid_bytes = &uuid.as_bytes()[..];
@@ -2221,6 +2235,7 @@ impl<C: Clocks + Clone> Database<C> {
         mut conn: rusqlite::Connection,
         read_write: bool,
     ) -> Result<Database<C>, Error> {
+        check_sqlite_version()?;
         set_integrity_pragmas(&mut conn)?;
         check_schema_version(&conn)?;
 

server/db/upgrade/mod.rs

@@ -90,6 +90,7 @@ fn upgrade(args: &Args, target_ver: i32, conn: &mut rusqlite::Connection) -> Res
 }
 
 pub fn run(args: &Args, conn: &mut rusqlite::Connection) -> Result<(), Error> {
+    db::check_sqlite_version()?;
     db::set_integrity_pragmas(conn)?;
     set_journal_mode(&conn, args.preset_journal)?;
     upgrade(args, db::EXPECTED_VERSION, conn)?;