Use SmallCString in most places

src/inner_connection.rs

@@ -1,4 +1,4 @@
-use std::ffi::CString;
+use std::ffi::CStr;
 use std::os::raw::{c_char, c_int};
 #[cfg(feature = "load_extension")]
 use std::path::Path;
@@ -8,7 +8,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex};
 
 use super::ffi;
-use super::{str_for_sqlite, str_to_cstring};
+use super::str_for_sqlite;
 use super::{Connection, InterruptHandle, OpenFlags, Result};
 use crate::error::{error_from_handle, error_from_sqlite_code, Error};
 use crate::raw_statement::RawStatement;
@@ -51,9 +51,9 @@ impl InnerConnection {
     }
 
     pub fn open_with_flags(
-        c_path: &CString,
+        c_path: &CStr,
         flags: OpenFlags,
-        vfs: Option<&CString>,
+        vfs: Option<&CStr>,
     ) -> Result<InnerConnection> {
         #[cfg(not(feature = "bundled"))]
         ensure_valid_sqlite_version();
@@ -171,7 +171,8 @@ impl InnerConnection {
     }
 
     pub fn execute_batch(&mut self, sql: &str) -> Result<()> {
-        let c_sql = str_to_cstring(sql)?;
+        // use CString instead of SmallCString because it's probably big.
+        let c_sql = std::ffi::CString::new(sql)?;
         unsafe {
             let r = ffi::sqlite3_exec(
                 self.db(),
@@ -196,7 +197,7 @@ impl InnerConnection {
         unsafe {
             let mut errmsg: *mut c_char = ptr::null_mut();
             let r = if let Some(entry_point) = entry_point {
-                let c_entry = str_to_cstring(entry_point)?;
+                let c_entry = crate::str_to_cstring(entry_point)?;
                 ffi::sqlite3_load_extension(
                     self.db,
                     dylib_str.as_ptr(),

src/lib.rs

@@ -129,6 +129,7 @@ mod version;
 pub mod vtab;
 
 pub(crate) mod util;
+pub(crate) use util::SmallCString;
 
 // Number of cached prepared statements we'll hold on to.
 const STATEMENT_CACHE_DEFAULT_CAPACITY: usize = 16;
@@ -233,8 +234,8 @@ unsafe fn errmsg_to_string(errmsg: *const c_char) -> String {
     String::from_utf8_lossy(c_slice).into_owned()
 }
 
-fn str_to_cstring(s: &str) -> Result<CString> {
-    Ok(CString::new(s)?)
+fn str_to_cstring(s: &str) -> Result<SmallCString> {
+    Ok(SmallCString::new(s)?)
 }
 
 /// Returns `Ok((string ptr, len as c_int, SQLITE_STATIC | SQLITE_TRANSIENT))`
@@ -301,7 +302,7 @@ pub enum DatabaseName<'a> {
     feature = "modern_sqlite"
 ))]
 impl DatabaseName<'_> {
-    fn to_cstring(&self) -> Result<CString> {
+    fn to_cstring(&self) -> Result<util::SmallCString> {
         use self::DatabaseName::{Attached, Main, Temp};
         match *self {
             Main => str_to_cstring("main"),

src/session.rs

@@ -102,10 +102,11 @@ impl Session<'_> {
     /// Attach a table. `None` means all tables.
     pub fn attach(&mut self, table: Option<&str>) -> Result<()> {
         let table = if let Some(table) = table {
-            str_to_cstring(table)?.as_ptr()
+            Some(str_to_cstring(table)?)
         } else {
-            ptr::null()
+            None
         };
+        let table = table.as_ref().map(|s| s.as_ptr()).unwrap_or(ptr::null());
         unsafe { check!(ffi::sqlite3session_attach(self.s, table)) };
         Ok(())
     }
@@ -156,7 +157,8 @@ impl Session<'_> {
     /// Load the difference between tables.
     pub fn diff(&mut self, from: DatabaseName<'_>, table: &str) -> Result<()> {
         let from = from.to_cstring()?;
-        let table = str_to_cstring(table)?.as_ptr();
+        let table = str_to_cstring(table)?;
+        let table = table.as_ptr();
         unsafe {
             let mut errmsg = ptr::null_mut();
             let r =