Casts to avoid integer overflow in matrix row/columns. (#1281)

* Casts to avoid integer overflow in matrix row/columns.

* Updated ChangeLog.

* Missed a few spots.

* Missed another spot.

* Even more spots missed.

* Remove an extraneous cast that breaks the Vector::end iterator.

* Updated Changelog again.

Author: LTLA

ChangeLog

@@ -1,3 +1,11 @@
+2023-10-22 Aaron Lun <[email protected]>
+
+	* inst/include/Rcpp/vector/MatrixColumn.h: Cast integer index
+	to R_xlen_t to avoid integer overflow with large matrices.
+	* inst/include/Rcpp/vector/MatrixRow.h: Ditto.
+	* inst/include/Rcpp/vector/Vector.h: Remove stray cast to int
+	that causes overflow when returning the end iterator.
+
 2023-09-30  Dirk Eddelbuettel  <[email protected]>
 
 	* vignettes/rmd/Rcpp-introduction.Rmd (Rcpp): Correct caption of

inst/include/Rcpp/vector/MatrixColumn.h

@@ -129,7 +129,7 @@ class ConstMatrixColumn : public VectorBase<RTYPE,true,ConstMatrixColumn<RTYPE>
 
     ConstMatrixColumn( const MATRIX& parent, int i ) :
         n(parent.nrow()),
-        const_start(parent.begin() + i *n)
+        const_start(parent.begin() + static_cast<R_xlen_t>(i) * n)
     {
         if( i < 0 || i >= parent.ncol() ) {
             const char* fmt = "Column index is out of bounds: "

inst/include/Rcpp/vector/MatrixRow.h

@@ -169,7 +169,7 @@ class MatrixRow : public VectorBase< RTYPE, true, MatrixRow<RTYPE> > {
     }
 
     inline reference operator[]( int i ) const {
-        return parent[ row + i * parent_nrow ] ;
+        return parent[ row + static_cast<R_xlen_t>(i) * parent_nrow ] ;
     }
 
     inline iterator begin(){
@@ -206,9 +206,9 @@ class MatrixRow : public VectorBase< RTYPE, true, MatrixRow<RTYPE> > {
     int parent_nrow ;
     int row ;
 
-    inline int get_parent_index(int i) const {
-        RCPP_DEBUG_4( "MatrixRow<%d>::get_parent_index(int = %d), parent_nrow = %d >> %d\n", RTYPE, i, parent_nrow, i*parent_nrow )
-        return i * parent_nrow ;
+    inline R_xlen_t get_parent_index(int i) const {
+        RCPP_DEBUG_4( "MatrixRow<%d>::get_parent_index(int = %d), parent_nrow = %d >> %d\n", RTYPE, i, parent_nrow, static_cast<R_xlen_t>(i) * parent_nrow )
+        return static_cast<R_xlen_t>(i) * parent_nrow ;
     }
 } ;
 
@@ -310,7 +310,7 @@ class ConstMatrixRow : public VectorBase< RTYPE, true, ConstMatrixRow<RTYPE> > {
     {} ;
 
     inline const_reference operator[]( int i ) const {
-        return parent[ row + i * parent_nrow ] ;
+        return parent[ row + static_cast<R_xlen_t>(i) * parent_nrow ] ;
     }
 
     inline const_iterator begin() const {
@@ -331,9 +331,9 @@ class ConstMatrixRow : public VectorBase< RTYPE, true, ConstMatrixRow<RTYPE> > {
     int parent_nrow ;
     int row ;
 
-    inline int get_parent_index(int i) const {
-        RCPP_DEBUG_4( "ConstMatrixRow<%d>::get_parent_index(int = %d), parent_nrow = %d >> %d\n", RTYPE, i, parent_nrow, i*parent_nrow )
-        return i * parent_nrow ;
+    inline R_xlen_t get_parent_index(int i) const {
+        RCPP_DEBUG_4( "ConstMatrixRow<%d>::get_parent_index(int = %d), parent_nrow = %d >> %d\n", RTYPE, i, parent_nrow, static_cast<R_xlen_t>(i) * parent_nrow )
+        return static_cast<R_xlen_t>(i) * parent_nrow ;
     }
 } ;
 }

inst/include/Rcpp/vector/Vector.h

@@ -331,7 +331,7 @@ class Vector :
     }
 
     inline iterator begin() { return cache.get() ; }
-    inline iterator end() { return cache.get() + static_cast<int>(size()) ; }
+    inline iterator end() { return cache.get() + size() ; }
     inline const_iterator begin() const{ return cache.get_const() ; }
     inline const_iterator end() const{ return cache.get_const() + size() ; }
     inline const_iterator cbegin() const{ return cache.get_const() ; }