1 files changed, 88 insertions, 0 deletions
diff --git a/third_party/rust/wasmparser/src/readers/alias_section.rs b/third_party/rust/wasmparser/src/readers/alias_section.rs
new file mode 100644
index 0000000000..bf64c18069
--- /dev/null
+++ b/third_party/rust/wasmparser/src/readers/alias_section.rs
@@ -0,0 +1,88 @@
+use crate::{
+    BinaryReader, BinaryReaderError, ExternalKind, Range, Result, SectionIteratorLimited,
+    SectionReader, SectionWithLimitedItems,
+};
+
+#[derive(Clone)]
+pub struct AliasSectionReader<'a> {
+    reader: BinaryReader<'a>,
+    count: u32,
+}
+
+#[derive(Debug)]
+pub struct Alias {
+    pub instance: AliasedInstance,
+    pub kind: ExternalKind,
+    pub index: u32,
+}
+
+#[derive(Debug)]
+pub enum AliasedInstance {
+    Parent,
+    Child(u32),
+}
+
+impl<'a> AliasSectionReader<'a> {
+    pub fn new(data: &'a [u8], offset: usize) -> Result<AliasSectionReader<'a>> {
+        let mut reader = BinaryReader::new_with_offset(data, offset);
+        let count = reader.read_var_u32()?;
+        Ok(AliasSectionReader { reader, count })
+    }
+
+    pub fn original_position(&self) -> usize {
+        self.reader.original_position()
+    }
+
+    pub fn get_count(&self) -> u32 {
+        self.count
+    }
+
+    pub fn read(&mut self) -> Result<Alias> {
+        Ok(Alias {
+            instance: match self.reader.read_u8()? {
+                0x00 => AliasedInstance::Child(self.reader.read_var_u32()?),
+                0x01 => AliasedInstance::Parent,
+                _ => {
+                    return Err(BinaryReaderError::new(
+                        "invalid byte in alias",
+                        self.original_position() - 1,
+                    ))
+                }
+            },
+            kind: self.reader.read_external_kind()?,
+            index: self.reader.read_var_u32()?,
+        })
+    }
+}
+
+impl<'a> SectionReader for AliasSectionReader<'a> {
+    type Item = Alias;
+
+    fn read(&mut self) -> Result<Self::Item> {
+        AliasSectionReader::read(self)
+    }
+    fn eof(&self) -> bool {
+        self.reader.eof()
+    }
+    fn original_position(&self) -> usize {
+        AliasSectionReader::original_position(self)
+    }
+    fn range(&self) -> Range {
+        self.reader.range()
+    }
+}
+
+impl<'a> SectionWithLimitedItems for AliasSectionReader<'a> {
+    fn get_count(&self) -> u32 {
+        AliasSectionReader::get_count(self)
+    }
+}
+
+impl<'a> IntoIterator for AliasSectionReader<'a> {
+    type Item = Result<Alias>;
+    type IntoIter = SectionIteratorLimited<AliasSectionReader<'a>>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        SectionIteratorLimited::new(self)
+    }
+}