1 files changed, 207 insertions, 0 deletions
diff --git a/third_party/rust/object/src/read/coff/comdat.rs b/third_party/rust/object/src/read/coff/comdat.rs
new file mode 100644
index 0000000000..22e061a236
--- /dev/null
+++ b/third_party/rust/object/src/read/coff/comdat.rs
@@ -0,0 +1,207 @@
+use core::str;
+
+use crate::endian::LittleEndian as LE;
+use crate::pe;
+use crate::read::{
+    self, ComdatKind, ObjectComdat, ReadError, ReadRef, Result, SectionIndex, SymbolIndex,
+};
+
+use super::{CoffFile, CoffHeader, ImageSymbol};
+
+/// An iterator over the COMDAT section groups of a `CoffBigFile`.
+pub type CoffBigComdatIterator<'data, 'file, R = &'data [u8]> =
+    CoffComdatIterator<'data, 'file, R, pe::AnonObjectHeaderBigobj>;
+
+/// An iterator over the COMDAT section groups of a `CoffFile`.
+#[derive(Debug)]
+pub struct CoffComdatIterator<
+    'data,
+    'file,
+    R: ReadRef<'data> = &'data [u8],
+    Coff: CoffHeader = pe::ImageFileHeader,
+> {
+    pub(super) file: &'file CoffFile<'data, R, Coff>,
+    pub(super) index: usize,
+}
+
+impl<'data, 'file, R: ReadRef<'data>, Coff: CoffHeader> Iterator
+    for CoffComdatIterator<'data, 'file, R, Coff>
+{
+    type Item = CoffComdat<'data, 'file, R, Coff>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            let index = self.index;
+            let symbol = self.file.common.symbols.symbol(index).ok()?;
+            self.index += 1 + symbol.number_of_aux_symbols() as usize;
+            if let Some(comdat) = CoffComdat::parse(self.file, symbol, index) {
+                return Some(comdat);
+            }
+        }
+    }
+}
+
+/// A COMDAT section group of a `CoffBigFile`.
+pub type CoffBigComdat<'data, 'file, R = &'data [u8]> =
+    CoffComdat<'data, 'file, R, pe::AnonObjectHeaderBigobj>;
+
+/// A COMDAT section group of a `CoffFile`.
+#[derive(Debug)]
+pub struct CoffComdat<
+    'data,
+    'file,
+    R: ReadRef<'data> = &'data [u8],
+    Coff: CoffHeader = pe::ImageFileHeader,
+> {
+    file: &'file CoffFile<'data, R, Coff>,
+    symbol_index: SymbolIndex,
+    symbol: &'data Coff::ImageSymbol,
+    selection: u8,
+}
+
+impl<'data, 'file, R: ReadRef<'data>, Coff: CoffHeader> CoffComdat<'data, 'file, R, Coff> {
+    fn parse(
+        file: &'file CoffFile<'data, R, Coff>,
+        section_symbol: &'data Coff::ImageSymbol,
+        index: usize,
+    ) -> Option<CoffComdat<'data, 'file, R, Coff>> {
+        // Must be a section symbol.
+        if !section_symbol.has_aux_section() {
+            return None;
+        }
+
+        // Auxiliary record must have a non-associative selection.
+        let aux = file.common.symbols.aux_section(index).ok()?;
+        let selection = aux.selection;
+        if selection == 0 || selection == pe::IMAGE_COMDAT_SELECT_ASSOCIATIVE {
+            return None;
+        }
+
+        // Find the COMDAT symbol.
+        let mut symbol_index = index;
+        let mut symbol = section_symbol;
+        let section_number = section_symbol.section_number();
+        loop {
+            symbol_index += 1 + symbol.number_of_aux_symbols() as usize;
+            symbol = file.common.symbols.symbol(symbol_index).ok()?;
+            if section_number == symbol.section_number() {
+                break;
+            }
+        }
+
+        Some(CoffComdat {
+            file,
+            symbol_index: SymbolIndex(symbol_index),
+            symbol,
+            selection,
+        })
+    }
+}
+
+impl<'data, 'file, R: ReadRef<'data>, Coff: CoffHeader> read::private::Sealed
+    for CoffComdat<'data, 'file, R, Coff>
+{
+}
+
+impl<'data, 'file, R: ReadRef<'data>, Coff: CoffHeader> ObjectComdat<'data>
+    for CoffComdat<'data, 'file, R, Coff>
+{
+    type SectionIterator = CoffComdatSectionIterator<'data, 'file, R, Coff>;
+
+    #[inline]
+    fn kind(&self) -> ComdatKind {
+        match self.selection {
+            pe::IMAGE_COMDAT_SELECT_NODUPLICATES => ComdatKind::NoDuplicates,
+            pe::IMAGE_COMDAT_SELECT_ANY => ComdatKind::Any,
+            pe::IMAGE_COMDAT_SELECT_SAME_SIZE => ComdatKind::SameSize,
+            pe::IMAGE_COMDAT_SELECT_EXACT_MATCH => ComdatKind::ExactMatch,
+            pe::IMAGE_COMDAT_SELECT_LARGEST => ComdatKind::Largest,
+            pe::IMAGE_COMDAT_SELECT_NEWEST => ComdatKind::Newest,
+            _ => ComdatKind::Unknown,
+        }
+    }
+
+    #[inline]
+    fn symbol(&self) -> SymbolIndex {
+        self.symbol_index
+    }
+
+    #[inline]
+    fn name_bytes(&self) -> Result<&[u8]> {
+        // Find the name of first symbol referring to the section.
+        self.symbol.name(self.file.common.symbols.strings())
+    }
+
+    #[inline]
+    fn name(&self) -> Result<&str> {
+        let bytes = self.name_bytes()?;
+        str::from_utf8(bytes)
+            .ok()
+            .read_error("Non UTF-8 COFF COMDAT name")
+    }
+
+    #[inline]
+    fn sections(&self) -> Self::SectionIterator {
+        CoffComdatSectionIterator {
+            file: self.file,
+            section_number: self.symbol.section_number(),
+            index: 0,
+        }
+    }
+}
+
+/// An iterator over the sections in a COMDAT section group of a `CoffBigFile`.
+pub type CoffBigComdatSectionIterator<'data, 'file, R = &'data [u8]> =
+    CoffComdatSectionIterator<'data, 'file, R, pe::AnonObjectHeaderBigobj>;
+
+/// An iterator over the sections in a COMDAT section group of a `CoffFile`.
+#[derive(Debug)]
+pub struct CoffComdatSectionIterator<
+    'data,
+    'file,
+    R: ReadRef<'data> = &'data [u8],
+    Coff: CoffHeader = pe::ImageFileHeader,
+> {
+    file: &'file CoffFile<'data, R, Coff>,
+    section_number: i32,
+    index: usize,
+}
+
+impl<'data, 'file, R: ReadRef<'data>, Coff: CoffHeader> Iterator
+    for CoffComdatSectionIterator<'data, 'file, R, Coff>
+{
+    type Item = SectionIndex;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        // Find associated COMDAT symbols.
+        // TODO: it seems gcc doesn't use associated symbols for this
+        loop {
+            let index = self.index;
+            let symbol = self.file.common.symbols.symbol(index).ok()?;
+            self.index += 1 + symbol.number_of_aux_symbols() as usize;
+
+            // Must be a section symbol.
+            if !symbol.has_aux_section() {
+                continue;
+            }
+
+            let section_number = symbol.section_number();
+
+            let aux = self.file.common.symbols.aux_section(index).ok()?;
+            if aux.selection == pe::IMAGE_COMDAT_SELECT_ASSOCIATIVE {
+                let number = if Coff::is_type_bigobj() {
+                    u32::from(aux.number.get(LE)) | (u32::from(aux.high_number.get(LE)) << 16)
+                } else {
+                    u32::from(aux.number.get(LE))
+                };
+                if number as i32 == self.section_number {
+                    return Some(SectionIndex(section_number as usize));
+                }
+            } else if aux.selection != 0 {
+                if section_number == self.section_number {
+                    return Some(SectionIndex(section_number as usize));
+                }
+            }
+        }
+    }
+}