Addition of checks on the size of array and index in sort_index

Author: jvdp1

example/sorting/CMakeLists.txt

@@ -1,4 +1,5 @@
 ADD_EXAMPLE(ord_sort)
 ADD_EXAMPLE(sort)
+ADD_EXAMPLE(sort_index)
 ADD_EXAMPLE(radix_sort)
-ADD_EXAMPLE(sort_bitset)
+ADD_EXAMPLE(sort_bitset)

example/sorting/example_sort_index.f90

@@ -0,0 +1,15 @@
+program example_sort_index
+  use stdlib_sorting, only: sort_index
+  implicit none
+  integer, allocatable :: array(:)
+  integer, allocatable :: index(:)
+
+  array = [5, 4, 3, 1, 10, 4, 9]
+  allocate(index, mold=array)
+
+  call sort_index(array, index)
+
+  print *, array   !print [1, 3, 4, 4, 5, 9, 10]
+  print *, index   !print [4, 3, 2, 6, 1, 7, 5]
+
+end program example_sort_index

src/stdlib_sorting_sort_index.fypp

@@ -93,7 +93,7 @@ contains
 ! deal with Fortran arrays of intrinsic types and not the full generality
 ! of Rust's arrays and lists for arbitrary types. It also adds the
 ! estimation of the optimal `run size` as suggested in Tim Peters'
-! original listsort.txt, and the optional `work` and `iwork` arraya to be
+! original listsort.txt, and the optional `work` and `iwork` arrays to be
 ! used as scratch memory.
 
         ${t1}$, intent(inout)                    :: array(0:)
@@ -106,8 +106,16 @@ contains
         ${t2}$, allocatable :: buf(:)
         ${ti}$, allocatable :: ibuf(:)
 
+        if ( size(array, kind=int_index) > huge(1_${ki}$) ) then
+            error stop "Too many entries for the chosen kind."
+        end if
+
         array_size = size(array, kind=${ki}$)
 
+        if ( size(index, kind=${ki}$) < array_size ) then
+            error stop "index array is too small."
+        end if
+
         do i = 0, array_size-1
             index(i) = i+1
         end do