1 files changed, 103 insertions, 0 deletions
diff --git a/third_party/rust/minidump-writer/src/dir_section.rs b/third_party/rust/minidump-writer/src/dir_section.rs
new file mode 100644
index 0000000000..ced5a2d156
--- /dev/null
+++ b/third_party/rust/minidump-writer/src/dir_section.rs
@@ -0,0 +1,103 @@
+use crate::{
+    mem_writer::{Buffer, MemoryArrayWriter, MemoryWriterError},
+    minidump_format::MDRawDirectory,
+};
+use std::io::{Error, Seek, Write};
+
+pub type DumpBuf = Buffer;
+
+#[derive(Debug, thiserror::Error)]
+pub enum FileWriterError {
+    #[error("IO error")]
+    IOError(#[from] Error),
+    #[error("Failed to write to memory")]
+    MemoryWriterError(#[from] MemoryWriterError),
+}
+
+/// Utility that wraps writing minidump directory entries to an I/O stream, generally
+/// a [`std::fs::File`].
+#[derive(Debug)]
+pub struct DirSection<'a, W>
+where
+    W: Write + Seek,
+{
+    curr_idx: usize,
+    section: MemoryArrayWriter<MDRawDirectory>,
+    /// If we have to append to some file, we have to know where we currently are
+    destination_start_offset: u64,
+    destination: &'a mut W,
+    last_position_written_to_file: u64,
+}
+
+impl<'a, W> DirSection<'a, W>
+where
+    W: Write + Seek,
+{
+    pub fn new(
+        buffer: &mut DumpBuf,
+        index_length: u32,
+        destination: &'a mut W,
+    ) -> std::result::Result<Self, FileWriterError> {
+        let dir_section =
+            MemoryArrayWriter::<MDRawDirectory>::alloc_array(buffer, index_length as usize)?;
+
+        Ok(Self {
+            curr_idx: 0,
+            section: dir_section,
+            destination_start_offset: destination.stream_position()?,
+            destination,
+            last_position_written_to_file: 0,
+        })
+    }
+
+    #[inline]
+    pub fn position(&self) -> u32 {
+        self.section.position
+    }
+
+    pub fn dump_dir_entry(
+        &mut self,
+        buffer: &mut DumpBuf,
+        dirent: MDRawDirectory,
+    ) -> std::result::Result<(), FileWriterError> {
+        self.section.set_value_at(buffer, dirent, self.curr_idx)?;
+
+        // Now write it to file
+
+        // First get all the positions
+        let curr_file_pos = self.destination.stream_position()?;
+        let idx_pos = self.section.location_of_index(self.curr_idx);
+        self.curr_idx += 1;
+
+        self.destination.seek(std::io::SeekFrom::Start(
+            self.destination_start_offset + idx_pos.rva as u64,
+        ))?;
+        let start = idx_pos.rva as usize;
+        let end = (idx_pos.rva + idx_pos.data_size) as usize;
+        self.destination.write_all(&buffer[start..end])?;
+
+        // Reset file-position
+        self.destination
+            .seek(std::io::SeekFrom::Start(curr_file_pos))?;
+
+        Ok(())
+    }
+
+    /// Writes 2 things to file:
+    /// 1. The given dirent into the dir section in the header (if any is given)
+    /// 2. Everything in the in-memory buffer that was added since the last call to this function
+    pub fn write_to_file(
+        &mut self,
+        buffer: &mut DumpBuf,
+        dirent: Option<MDRawDirectory>,
+    ) -> std::result::Result<(), FileWriterError> {
+        if let Some(dirent) = dirent {
+            self.dump_dir_entry(buffer, dirent)?;
+        }
+
+        let start_pos = self.last_position_written_to_file as usize;
+        self.destination.write_all(&buffer[start_pos..])?;
+        self.last_position_written_to_file = buffer.position();
+        Ok(())
+    }
+}