Merge branch 'master' into gwenn-stmt-cache

src/blob.rs

@@ -17,6 +17,7 @@
 //! extern crate rusqlite;
 //!
 //! use rusqlite::{Connection, DatabaseName};
+//! use rusqlite::blob::ZeroBlob;
 //! use std::io::{Read, Write, Seek, SeekFrom};
 //!
 //! fn main() {
@@ -38,7 +39,7 @@
 //!     let bytes_read = blob.read(&mut buf[..]).unwrap();
 //!     assert_eq!(bytes_read, 10); // note we read 10 bytes because the blob has size 10
 //!
-//!     db.execute("INSERT INTO test (content) VALUES (ZEROBLOB(64))", &[]).unwrap();
+//!     db.execute("INSERT INTO test (content) VALUES (?)", &[&ZeroBlob(64)]).unwrap();
 //!
 //!     // given a new row ID, we can reopen the blob on that row
 //!     let rowid = db.last_insert_rowid();
@@ -51,8 +52,10 @@ use std::io;
 use std::cmp::min;
 use std::mem;
 use std::ptr;
+use libc::c_int;
 
 use super::ffi;
+use super::types::ToSql;
 use {Result, Connection, DatabaseName};
 
 /// Handle to an open BLOB.
@@ -232,6 +235,19 @@ impl<'conn> Drop for Blob<'conn> {
     }
 }
 
+/// BLOB of length N that is filled with zeroes.
+/// Zeroblobs are intended to serve as placeholders for BLOBs whose content is later written using incremental BLOB I/O routines.
+/// A negative value for the zeroblob results in a zero-length BLOB.
+#[derive(Copy,Clone)]
+pub struct ZeroBlob(pub i32);
+
+impl ToSql for ZeroBlob {
+    unsafe fn bind_parameter(&self, stmt: *mut ffi::sqlite3_stmt, col: c_int) -> c_int {
+        let ZeroBlob(length) = *self;
+        ffi::sqlite3_bind_zeroblob(stmt, col, length)
+    }
+}
+
 #[cfg(test)]
 mod test {
     use std::io::{BufReader, BufRead, BufWriter, Read, Write, Seek, SeekFrom};

src/functions.rs

@@ -489,9 +489,10 @@ impl InnerConnection {
         where D: Aggregate<A, T>,
               T: ToResult
     {
-        unsafe fn aggregate_context<A>(ctx: *mut sqlite3_context) -> Option<*mut *mut A> {
-            let pac = ffi::sqlite3_aggregate_context(ctx, ::std::mem::size_of::<*mut A>() as c_int)
-                            as *mut *mut A;
+        unsafe fn aggregate_context<A>(ctx: *mut sqlite3_context,
+                                       bytes: usize)
+                                       -> Option<*mut *mut A> {
+            let pac = ffi::sqlite3_aggregate_context(ctx, bytes as c_int) as *mut *mut A;
             if pac.is_null() {
                 return None;
             }
@@ -525,7 +526,7 @@ impl InnerConnection {
             assert!(!boxed_aggr.is_null(),
                     "Internal error - null aggregate pointer");
 
-            let pac = match aggregate_context(ctx) {
+            let pac = match aggregate_context(ctx, ::std::mem::size_of::<*mut A>()) {
                 Some(pac) => pac,
                 None => {
                     ffi::sqlite3_result_error_nomem(ctx);
@@ -556,19 +557,18 @@ impl InnerConnection {
             assert!(!boxed_aggr.is_null(),
                     "Internal error - null aggregate pointer");
 
-            let pac = match aggregate_context(ctx) {
-                Some(pac) => pac,
-                None => {
-                    ffi::sqlite3_result_error_nomem(ctx);
-                    return;
+            // Within the xFinal callback, it is customary to set N=0 in calls to
+            // sqlite3_aggregate_context(C,N) so that no pointless memory allocations occur.
+            let a: Option<A> = match aggregate_context(ctx, 0) {
+                Some(pac) => {
+                    if (*pac).is_null() {
+                        None
+                    } else {
+                        let a = Box::from_raw(*pac);
+                        Some(*a)
+                    }
                 }
-            };
-
-            let a: Option<A> = if (*pac).is_null() {
-                None
-            } else {
-                let a = Box::from_raw(*pac);
-                Some(*a)
+                None => None,
             };
 
             match (*boxed_aggr).finalize(a) {

src/lib.rs

@@ -495,6 +495,18 @@ impl Connection {
             self.db.borrow_mut().load_extension(dylib_path.as_ref(), entry_point)
         }
 
+    /// Get access to the underlying SQLite database connection handle.
+    ///
+    /// # Warning
+    ///
+    /// You should not need to use this function. If you do need to, please [open an issue
+    /// on the rusqlite repository](https://github.com/jgallagher/rusqlite/issues) and describe
+    /// your use case. This function is unsafe because it gives you raw access to the SQLite
+    /// connection, and what you do with it could impact the safety of this `Connection`.
+    pub unsafe fn handle(&self) -> *mut ffi::Struct_sqlite3 {
+        self.db.borrow().db()
+    }
+
     fn decode_result(&self, code: c_int) -> Result<()> {
         self.db.borrow_mut().decode_result(code)
     }
@@ -999,6 +1011,9 @@ pub type SqliteRows<'stmt> = Rows<'stmt>;
 ///
 /// ## Warning
 ///
+/// Strongly consider using `query_map` or `query_and_then` instead of `query`; the former do not
+/// suffer from the following problem.
+///
 /// Due to the way SQLite returns result rows of a query, it is not safe to attempt to get values
 /// from a row after it has become stale (i.e., `next()` has been called again on the `Rows`
 /// iterator). For example:
@@ -1010,7 +1025,7 @@ pub type SqliteRows<'stmt> = Rows<'stmt>;
 ///     let mut rows = try!(stmt.query(&[]));
 ///
 ///     let row0 = try!(rows.next().unwrap());
-///     // row 0 is value now...
+///     // row 0 is valid for now...
 ///
 ///     let row1 = try!(rows.next().unwrap());
 ///     // row 0 is now STALE, and row 1 is valid
@@ -1024,12 +1039,6 @@ pub type SqliteRows<'stmt> = Rows<'stmt>;
 /// (which would result in a collection of rows, only the last of which can safely be used) and
 /// `min`/`max` (which could return a stale row unless the last row happened to be the min or max,
 /// respectively).
-///
-/// This problem could be solved by changing the signature of `next` to tie the lifetime of the
-/// returned row to the lifetime of (a mutable reference to) the result rows handle, but this would
-/// no longer implement `Iterator`, and therefore you would lose access to the majority of
-/// functions which are useful (such as support for `for ... in ...` looping, `map`, `filter`,
-/// etc.).
 pub struct Rows<'stmt> {
     stmt: &'stmt Statement<'stmt>,
     current_row: Rc<Cell<c_int>>,