Merge remote-tracking branch 'jgallagher/master' into vtab

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

@@ -509,9 +509,10 @@ 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;
             }
@@ -545,7 +546,7 @@ 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);
@@ -576,19 +577,18 @@ 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) {