Fix writing of aligned empty sections

src/write/elf/object.rs

@@ -323,12 +323,9 @@ impl<'a> Object<'a> {
             }
         }
         for (index, section) in self.sections.iter().enumerate() {
-            let len = section.data.len();
-            if len != 0 {
-                writer.write_align(section.align as usize);
-                debug_assert_eq!(section_offsets[index].offset, writer.len());
-                writer.write(&section.data);
-            }
+            writer.write_align(section.align as usize);
+            debug_assert_eq!(section_offsets[index].offset, writer.len());
+            writer.write(&section.data);
         }
 
         // Write symbols.

tests/aligned_sections.rs

@@ -0,0 +1,23 @@
+#![cfg(feature = "write")]
+
+use object::{
+    write::{Object, StreamingBuffer},
+    Architecture, BinaryFormat, Endianness, SectionKind,
+};
+
+#[test]
+fn aligned_sections() {
+    let mut object = Object::new(BinaryFormat::Elf, Architecture::X86_64, Endianness::Little);
+
+    let text_section_id = object.add_section(vec![], b".text".to_vec(), SectionKind::Text);
+    let text_section = object.section_mut(text_section_id);
+    text_section.set_data(&[][..], 4096);
+
+    let data_section_id = object.add_section(vec![], b".data".to_vec(), SectionKind::Data);
+    let data_section = object.section_mut(data_section_id);
+    data_section.set_data(&b"1234"[..], 16);
+
+    let mut buffer = StreamingBuffer::new(vec![]);
+    object.emit(&mut buffer).unwrap();
+    buffer.result().unwrap();
+}