From 89f6a2782ba45e5e1bc730fbba300008e85484aa Mon Sep 17 00:00:00 2001
From: Gwilym Inzani <email@gwilym.dev>
Date: Wed, 3 Apr 2024 14:03:42 +0100
Subject: [PATCH] Allow loading of the dwarf information from the gba rom

---
 agb-addr2line/Cargo.toml        |  2 +
 agb-addr2line/src/load_dwarf.rs | 74 +++++++++++++++++++++++++++++++++
 agb-addr2line/src/main.rs       |  8 ++--
 3 files changed, 81 insertions(+), 3 deletions(-)
 create mode 100644 agb-addr2line/src/load_dwarf.rs

diff --git a/agb-addr2line/Cargo.toml b/agb-addr2line/Cargo.toml
index 63130c8b..22aee0ef 100644
--- a/agb-addr2line/Cargo.toml
+++ b/agb-addr2line/Cargo.toml
@@ -15,6 +15,8 @@ addr2line = { version = "0.21", default-features = false, features = [
     "std-object",
 ] }
 colored = "2"
+rmp-serde = "1"
+lz4_flex = "0.11"
 
 [profile.dev]
 opt-level = 3
diff --git a/agb-addr2line/src/load_dwarf.rs b/agb-addr2line/src/load_dwarf.rs
new file mode 100644
index 00000000..6282d531
--- /dev/null
+++ b/agb-addr2line/src/load_dwarf.rs
@@ -0,0 +1,74 @@
+use std::{borrow::Cow, collections::HashMap, io::Cursor, rc::Rc};
+
+use addr2line::{
+    gimli,
+    object::{self, Object},
+};
+use anyhow::bail;
+
+pub fn load_dwarf(
+    file_content: &[u8],
+) -> anyhow::Result<gimli::Dwarf<gimli::EndianRcSlice<gimli::RunTimeEndian>>> {
+    if let Ok(object) = object::File::parse(file_content) {
+        return load_from_object(&object);
+    }
+
+    let last_8_bytes = &file_content[file_content.len() - 8..];
+    let len = u32::from_le_bytes(last_8_bytes[0..4].try_into()?) as usize;
+    let version = u32::from_le_bytes(last_8_bytes[4..].try_into()?) as usize;
+
+    if version != 1 {
+        bail!("Only version 1 of the debug info is supported");
+    }
+
+    let compressed_debug_data = &file_content[file_content.len() - len - 8..file_content.len() - 8];
+
+    let decompressing_reader =
+        lz4_flex::frame::FrameDecoder::new(Cursor::new(compressed_debug_data));
+    let debug_info: HashMap<String, Vec<u8>> = rmp_serde::decode::from_read(decompressing_reader)?;
+
+    let dwarf = gimli::Dwarf::load(|id| {
+        let data = debug_info
+            .get(id.name())
+            .map(|data| Cow::Borrowed(data.as_slice()))
+            .unwrap_or(Cow::Borrowed(&[]));
+
+        Result::<_, gimli::Error>::Ok(gimli::EndianRcSlice::new(
+            Rc::from(&*data),
+            gimli::RunTimeEndian::Little,
+        ))
+    })?;
+
+    Ok(dwarf)
+}
+
+fn load_from_object<'file>(
+    object: &object::File<'file, &'file [u8]>,
+) -> anyhow::Result<gimli::Dwarf<gimli::EndianRcSlice<gimli::RunTimeEndian>>> {
+    let endian = if object.is_little_endian() {
+        gimli::RunTimeEndian::Little
+    } else {
+        gimli::RunTimeEndian::Big
+    };
+
+    fn load_section<'data: 'file, 'file, O, Endian>(
+        id: gimli::SectionId,
+        file: &'file O,
+        endian: Endian,
+    ) -> Result<gimli::EndianRcSlice<Endian>, gimli::Error>
+    where
+        O: object::Object<'data, 'file>,
+        Endian: gimli::Endianity,
+    {
+        use object::ObjectSection;
+
+        let data = file
+            .section_by_name(id.name())
+            .and_then(|section| section.uncompressed_data().ok())
+            .unwrap_or(Cow::Borrowed(&[]));
+        Ok(gimli::EndianRcSlice::new(Rc::from(&*data), endian))
+    }
+
+    let dwarf = gimli::Dwarf::load(|id| load_section(id, object, endian))?;
+    Ok(dwarf)
+}
diff --git a/agb-addr2line/src/main.rs b/agb-addr2line/src/main.rs
index 35f5bc3b..efb5bd62 100644
--- a/agb-addr2line/src/main.rs
+++ b/agb-addr2line/src/main.rs
@@ -6,11 +6,13 @@ use std::{
     time::SystemTime,
 };
 
-use addr2line::{gimli, object};
+use addr2line::gimli;
 use clap::Parser;
 use colored::Colorize;
+use load_dwarf::load_dwarf;
 
 mod gwilym_encoding;
+mod load_dwarf;
 
 #[derive(Parser, Debug)]
 #[command(version, about, long_about = None)]
@@ -46,9 +48,9 @@ fn main() -> anyhow::Result<()> {
         .unwrap_or(SystemTime::UNIX_EPOCH);
 
     let file = fs::read(&cli.elf_path)?;
-    let object = object::File::parse(file.as_slice())?;
+    let dwarf = load_dwarf(&file)?;
 
-    let ctx = addr2line::Context::new(&object)?;
+    let ctx = addr2line::Context::from_dwarf(dwarf)?;
 
     for (i, address) in gwilym_encoding::gwilym_decode(&cli.dump)?.enumerate() {
         print_address(&ctx, i, address.into(), modification_time)?;