Merge pull request #152 from magnusuMET/feature/raw_values

Add back get_raw_values/get_raw_values_into

netcdf/src/putget.rs

@@ -184,6 +184,34 @@ pub(crate) fn get_vars<T>(
     get_vars_mono(var, tp, start, count, stride, values.cast())
 }
 
+/// Non-typechecked version of get_vars
+/// to support getting a bag of bytes
+pub fn get_raw_values_into(
+    variable: &crate::Variable,
+    buffer: &mut [u8],
+    extents: crate::Extents,
+) -> crate::error::Result<()> {
+    let dims = variable.dimensions();
+    let (start, count, stride) = extents.get_start_count_stride(dims)?;
+    let number_of_elements = count.iter().copied().fold(1_usize, usize::saturating_mul);
+    let varsize = variable.vartype().size();
+    if number_of_elements * varsize != buffer.len() {
+        return Err("Buffer is not of requisite size".into());
+    }
+    checked_with_lock(|| unsafe {
+        netcdf_sys::nc_get_vars(
+            variable.ncid,
+            variable.varid,
+            start.as_ptr(),
+            count.as_ptr(),
+            stride.as_ptr(),
+            buffer.as_mut_ptr().cast(),
+        )
+    })?;
+
+    Ok(())
+}
+
 #[allow(clippy::too_many_lines)]
 fn put_vars_mono(
     var: &mut crate::VariableMut,

netcdf/src/variable.rs

@@ -537,6 +537,42 @@ impl<'g> Variable<'g> {
         let extents: Extents = extents.try_into().map_err(Into::into)?;
         self.values_to_mono(buffer, &extents)
     }
+
+    /// Fetches variable and returns the bytes.
+    /// It is up to the caller to decide what to do with these bytes,
+    /// including interpretation and freeing memory if
+    /// this is a vlen/string type
+    pub fn get_raw_values<E>(&self, extents: E) -> error::Result<Vec<u8>>
+    where
+        E: TryInto<Extents>,
+        E::Error: Into<error::Error>,
+    {
+        let extents: Extents = extents.try_into().map_err(Into::into)?;
+        let dims = self.dimensions();
+        let (_, count, _) = extents.get_start_count_stride(dims)?;
+        let number_of_elements = count.iter().copied().fold(1_usize, usize::saturating_mul);
+        let varsize = self.vartype().size();
+        let mut buffer = vec![0_u8; number_of_elements * varsize];
+
+        super::putget::get_raw_values_into(self, &mut buffer, extents)?;
+
+        Ok(buffer)
+    }
+
+    /// Fetches variable into provided buffer.
+    /// This functions returns bytes and it is up to the caller to
+    /// decide what to do with it, including freeing memory if
+    /// this is a vlen/string type
+    pub fn get_raw_values_into<E>(&self, buffer: &mut [u8], extents: E) -> error::Result<()>
+    where
+        E: TryInto<Extents>,
+        E::Error: Into<error::Error>,
+    {
+        let extents: Extents = extents.try_into().map_err(Into::into)?;
+        super::putget::get_raw_values_into(self, buffer, extents)?;
+
+        Ok(())
+    }
 }
 
 impl<'g> VariableMut<'g> {

netcdf/tests/common/mod.rs

@@ -1,4 +1,5 @@
 /// Get location of the test files
+#[allow(dead_code)]
 pub(crate) fn test_location() -> std::path::PathBuf {
     use std::path::Path;
 

netcdf/tests/lib.rs

@@ -1766,3 +1766,32 @@ fn close_file() {
     let f = netcdf::open(path).unwrap();
     f.close().unwrap();
 }
+
+#[test]
+fn read_raw_values() {
+    let path = test_location().join("sfc_pres_temp.nc");
+    let file = netcdf::open(path).unwrap();
+
+    let var = file.variable("pressure").unwrap();
+    let d_lat = 6;
+    let d_lon = 12;
+
+    let buffer = var.get_raw_values(..).unwrap();
+    assert_eq!(buffer.len(), d_lat * d_lon * std::mem::size_of::<f32>());
+    let buffer = var.get_raw_values((0, ..)).unwrap();
+    assert_eq!(buffer.len(), 1 * d_lon * std::mem::size_of::<f32>());
+    let buffer = var.get_raw_values((.., 0)).unwrap();
+    assert_eq!(buffer.len(), d_lat * 1 * std::mem::size_of::<f32>());
+
+    let mut buffer = vec![0; d_lat * d_lon * std::mem::size_of::<f32>()];
+    var.get_raw_values_into(&mut buffer, ..).unwrap();
+
+    var.get_raw_values_into(&mut buffer[..d_lon * 1 * 4], (0, ..))
+        .unwrap();
+
+    // Mismatched buffers
+    var.get_raw_values_into(&mut buffer[..d_lon * 1 * 4 - 1], (0, ..))
+        .unwrap_err();
+    var.get_raw_values_into(&mut buffer[..d_lon * 1 * 4 + 1], (0, ..))
+        .unwrap_err();
+}