Ensure the buffer provided to MPAS_io_get_var_generic is large enough.

A fixed size array is provided as an input buffer when reading 0d-char
character variables.
Call MPAS_io_inq_var prior to the read to get the size of the variable’s value,
and only proceed with the read if the variable’s value will fit in the
provided array.
Return an error code if the variable’s value is larger than the provided
input buffer.

Author: jim-p-w

src/framework/mpas_io.F

@@ -7,6 +7,9 @@
 !
 module mpas_io
 
+#define IO_DEBUG_WRITE(M, ARGS) !call mpas_log_write(M, ARGS)
+#define IO_ERROR_WRITE(M, ARGS) call mpas_log_write( M, ARGS, messageType=MPAS_LOG_ERR)
+
    use mpas_derived_types
    use mpas_attlist
    use mpas_dmpar
@@ -1847,6 +1850,13 @@ subroutine MPAS_io_get_var_generic(handle, fieldname, intVal, intArray1d, intArr
       character (len=:), pointer :: charVal_p
       character (len=:), dimension(:), pointer :: charArray1d_p
 
+      ! local variables returned from MPAS_io_inq_var
+      integer :: fieldtype
+      integer :: ndims
+      integer, dimension(:), pointer :: dimsizes
+      character (len=StrKIND), dimension(:), pointer :: dimnames
+      character (len=StrKIND) :: message
+
 #ifdef MPAS_SMIOL_SUPPORT
       type (SMIOLf_decomp), pointer :: null_decomp
 
@@ -1984,22 +1994,41 @@ subroutine MPAS_io_get_var_generic(handle, fieldname, intVal, intArray1d, intArr
 !         call mpas_log_write('  value is char')
 
          charVal_p => charVal
+
+         ! get the dimension of the char variable to ensure the provided output buffer is large enough
+         call MPAS_io_inq_var(handle, fieldname, fieldtype, ndims, dimnames, dimsizes, local_ierr)
+         do i = 1, ndims
+            message = '  MPAS_io_get_var_generic len(charVal):$i var "'//trim(fieldname)// &
+                      '" type is $i dim is $i '// trim(dimnames(i))//' size is $i'
+            IO_DEBUG_WRITE(message, intArgs=(/len(charVal), fieldtype, i, dimsizes(i)/))
+         end do
+         ! because charVal is provided, assume dimension 1 is the string length
+         if (dimsizes(1) > len(charVal)) then
+            local_ierr = MPAS_IO_ERR_INSUFFICIENT_BUF
+            message = 'Length of string variable "'//trim(fieldname)//'" in file "'//trim(handle % filename)//'"'
+            IO_ERROR_WRITE(message, intArgs=[0])
+            message = '    exceeds buffer size: len('//trim(fieldname)//')=$i, len(buffer)=$i'
+            IO_ERROR_WRITE(message, intArgs=(/dimsizes(1), len(charVal)/))
+         else
 #ifdef MPAS_SMIOL_SUPPORT
-         local_ierr = SMIOLf_get_var(handle % smiol_file, trim(fieldname), null_decomp, charVal_p)
+            local_ierr = SMIOLf_get_var(handle % smiol_file, trim(fieldname), null_decomp, charVal_p)
 #endif
 
 #ifdef MPAS_PIO_SUPPORT
-         if (field_cursor % fieldhandle % has_unlimited_dim) then
-            count2(1) = field_cursor % fieldhandle % dims(1) % dimsize
-            pio_ierr = PIO_get_var(handle % pio_file, field_cursor % fieldhandle % fieldid, start2, count2, tempchar)
-            charVal(1:count2(1)) = tempchar(1)(1:count2(1))
-         else
-            start1(1) = 1
-            count1(1) = field_cursor % fieldhandle % dims(1) % dimsize
-            pio_ierr = PIO_get_var(handle % pio_file, field_cursor % fieldhandle % fieldid, start1, count1, tempchar)
-            charVal(1:count1(1)) = tempchar(1)(1:count1(1))
-         end if
+            if (field_cursor % fieldhandle % has_unlimited_dim) then
+               count2(1) = field_cursor % fieldhandle % dims(1) % dimsize
+               pio_ierr = PIO_get_var(handle % pio_file, field_cursor % fieldhandle % fieldid, start2, count2, tempchar)
+               charVal(1:count2(1)) = tempchar(1)(1:count2(1))
+            else
+               start1(1) = 1
+               count1(1) = field_cursor % fieldhandle % dims(1) % dimsize
+               pio_ierr = PIO_get_var(handle % pio_file, field_cursor % fieldhandle % fieldid, start1, count1, tempchar)
+               charVal(1:count1(1)) = tempchar(1)(1:count1(1))
+            end if
 #endif
+         end if
+         deallocate(dimsizes)
+         deallocate(dimnames)
       else if (present(charArray1d)) then
 !         call mpas_log_write('  value is char1')
 #ifdef MPAS_PIO_SUPPORT
@@ -2765,6 +2794,13 @@ subroutine MPAS_io_get_var_generic(handle, fieldname, intVal, intArray1d, intArr
       end if
 
 !      call mpas_log_write('Checking for error')
+      if (local_ierr == MPAS_IO_ERR_INSUFFICIENT_BUF) then
+         call MPAS_io_err_mesg(handle % ioContext, local_ierr, .false.)
+         io_global_err = local_ierr
+         if (present(ierr)) ierr = local_ierr
+         return
+      endif
+
 #ifdef MPAS_PIO_SUPPORT
       if (pio_ierr /= PIO_noerr) then
          io_global_err = pio_ierr
@@ -6498,6 +6534,10 @@ subroutine MPAS_io_err_mesg(ioContext, ierr, fatal)
             call mpas_log_write('MPAS IO Error: Would clobber existing file', MPAS_LOG_ERR)
          case (MPAS_IO_ERR_NOEXIST_READ)
             call mpas_log_write('MPAS IO Error: Attempting to read a file which does not exist.', MPAS_LOG_ERR)
+         case (MPAS_IO_ERR_MISSING_DIM)
+            call mpas_log_write('MPAS IO Error: Attempting to read a dimension which does not exist.', MPAS_LOG_ERR)
+         case (MPAS_IO_ERR_INSUFFICIENT_BUF)
+            call mpas_log_write('MPAS IO Error: Attempting to read a variable into a buffer of insufficient size.', MPAS_LOG_ERR)
          case default
             call mpas_log_write('MPAS IO Error: Unrecognized error code...', MPAS_LOG_ERR)
       end select

src/framework/mpas_io_types.inc

@@ -65,7 +65,8 @@
                          MPAS_IO_ERR_UNIMPLEMENTED      = -18, &
                          MPAS_IO_ERR_WOULD_CLOBBER      = -19, &
                          MPAS_IO_ERR_NOEXIST_READ       = -20, &
-                         MPAS_IO_ERR_MISSING_DIM        = -21
+                         MPAS_IO_ERR_MISSING_DIM        = -21, &
+                         MPAS_IO_ERR_INSUFFICIENT_BUF   = -22
 
    type MPAS_IO_Handle_type
       logical :: initialized = .false.