Add symbol mapping feature (#118)

This allows users to "map" (or "link") symbols with different names so that they can be compared without having to update either the target or base objects. Symbol mappings are persisted in objdiff.json, so generators will need to ensure that they're preserved when updating. (Example: https://github.com/encounter/dtk-template/commit/d1334bb79e71af1a7b3b090bffda4adc483f722c)

Resolves #117

.github/workflows/build.yaml

@@ -110,11 +110,6 @@ jobs:
             name: linux-aarch64
             build: zigbuild
             features: default
-          - platform: ubuntu-latest
-            target: armv7-unknown-linux-musleabi
-            name: linux-armv7l
-            build: zigbuild
-            features: default
           - platform: windows-latest
             target: i686-pc-windows-msvc
             name: windows-x86

Cargo.toml

@@ -13,7 +13,7 @@ strip = "debuginfo"
 codegen-units = 1
 
 [workspace.package]
-version = "2.0.0"
+version = "2.3.0"
 authors = ["Luke Street <luke@street.dev>"]
 edition = "2021"
 license = "MIT OR Apache-2.0"

config.schema.json

@@ -133,6 +133,13 @@
         },
         "metadata": {
           "ref": "#/$defs/metadata"
+        },
+        "symbol_mappings": {
+          "type": "object",
+          "description": "Manual symbol mappings from target to base.",
+          "additionalProperties": {
+            "type": "string"
+          }
         }
       }
     },

objdiff-cli/Cargo.toml

@@ -11,7 +11,6 @@ description = """
 A local diffing tool for decompilation projects.
 """
 publish = false
-build = "build.rs"
 
 [dependencies]
 anyhow = "1.0"
@@ -29,3 +28,6 @@ supports-color = "3.0"
 time = { version = "0.3", features = ["formatting", "local-offset"] }
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+
+[target.'cfg(target_env = "musl")'.dependencies]
+mimalloc = "0.1"

objdiff-cli/build.rs

@@ -1,9 +0,0 @@
-fn main() {
-    let output = std::process::Command::new("git")
-        .args(["rev-parse", "HEAD"])
-        .output()
-        .expect("Failed to execute git");
-    let rev = String::from_utf8(output.stdout).expect("Failed to parse git output");
-    println!("cargo:rustc-env=GIT_COMMIT_SHA={rev}");
-    println!("cargo:rustc-rerun-if-changed=.git/HEAD");
-}

objdiff-cli/src/argp_version.rs

@@ -31,10 +31,9 @@ where T: FromArgs
             Ok(v) => {
                 if v.version {
                     println!(
-                        "{} {} {}",
+                        "{} {}",
                         command_name.first().unwrap_or(&""),
                         env!("CARGO_PKG_VERSION"),
-                        env!("GIT_COMMIT_SHA"),
                     );
                     std::process::exit(0);
                 } else {

objdiff-cli/src/cmd/diff.rs

@@ -102,26 +102,32 @@ pub fn run(args: Args) -> Result<()> {
                     let unit_path =
                         PathBuf::from_str(u).ok().and_then(|p| fs::canonicalize(p).ok());
 
-                    let Some(object) = project_config.objects.iter_mut().find_map(|obj| {
-                        if obj.name.as_deref() == Some(u) {
+                    let Some(object) = project_config
+                        .units
+                        .as_deref_mut()
+                        .unwrap_or_default()
+                        .iter_mut()
+                        .find_map(|obj| {
+                            if obj.name.as_deref() == Some(u) {
+                                resolve_paths(obj);
+                                return Some(obj);
+                            }
+
+                            let up = unit_path.as_deref()?;
+
                             resolve_paths(obj);
-                            return Some(obj);
-                        }
 
-                        let up = unit_path.as_deref()?;
+                            if [&obj.base_path, &obj.target_path]
+                                .into_iter()
+                                .filter_map(|p| p.as_ref().and_then(|p| p.canonicalize().ok()))
+                                .any(|p| p == up)
+                            {
+                                return Some(obj);
+                            }
 
-                        resolve_paths(obj);
-
-                        if [&obj.base_path, &obj.target_path]
-                            .into_iter()
-                            .filter_map(|p| p.as_ref().and_then(|p| p.canonicalize().ok()))
-                            .any(|p| p == up)
-                        {
-                            return Some(obj);
-                        }
-
-                        None
-                    }) else {
+                            None
+                        })
+                    else {
                         bail!("Unit not found: {}", u)
                     };
 
@@ -129,7 +135,13 @@ pub fn run(args: Args) -> Result<()> {
                 } else if let Some(symbol_name) = &args.symbol {
                     let mut idx = None;
                     let mut count = 0usize;
-                    for (i, obj) in project_config.objects.iter_mut().enumerate() {
+                    for (i, obj) in project_config
+                        .units
+                        .as_deref_mut()
+                        .unwrap_or_default()
+                        .iter_mut()
+                        .enumerate()
+                    {
                         resolve_paths(obj);
 
                         if obj
@@ -148,7 +160,7 @@ pub fn run(args: Args) -> Result<()> {
                     }
                     match (count, idx) {
                         (0, None) => bail!("Symbol not found: {}", symbol_name),
-                        (1, Some(i)) => &mut project_config.objects[i],
+                        (1, Some(i)) => &mut project_config.units_mut()[i],
                         (2.., Some(_)) => bail!(
                             "Multiple instances of {} were found, try specifying a unit",
                             symbol_name
@@ -303,7 +315,7 @@ fn find_function(obj: &ObjInfo, name: &str) -> Option<SymbolRef> {
     None
 }
 
-#[allow(dead_code)]
+#[expect(dead_code)]
 struct FunctionDiffUi {
     relax_reloc_diffs: bool,
     left_highlight: HighlightKind,
@@ -758,7 +770,7 @@ impl FunctionDiffUi {
         self.scroll_y += self.per_page / if half { 2 } else { 1 };
     }
 
-    #[allow(clippy::too_many_arguments)]
+    #[expect(clippy::too_many_arguments)]
     fn print_sym(
         &self,
         out: &mut Text<'static>,

objdiff-cli/src/cmd/report.rs

@@ -94,7 +94,7 @@ fn generate(args: GenerateArgs) -> Result<()> {
     };
     info!(
         "Generating report for {} units (using {} threads)",
-        project.objects.len(),
+        project.units().len(),
         if args.deduplicate { 1 } else { rayon::current_num_threads() }
     );
 
@@ -103,7 +103,7 @@ fn generate(args: GenerateArgs) -> Result<()> {
     let mut existing_functions: HashSet<String> = HashSet::new();
     if args.deduplicate {
         // If deduplicating, we need to run single-threaded
-        for object in &mut project.objects {
+        for object in project.units.as_deref_mut().unwrap_or_default() {
             if let Some(unit) = report_object(
                 object,
                 project_dir,
@@ -116,7 +116,9 @@ fn generate(args: GenerateArgs) -> Result<()> {
         }
     } else {
         let vec = project
-            .objects
+            .units
+            .as_deref_mut()
+            .unwrap_or_default()
             .par_iter_mut()
             .map(|object| {
                 report_object(
@@ -132,7 +134,7 @@ fn generate(args: GenerateArgs) -> Result<()> {
     }
     let measures = units.iter().flat_map(|u| u.measures.into_iter()).collect();
     let mut categories = Vec::new();
-    for category in &project.progress_categories {
+    for category in project.progress_categories() {
         categories.push(ReportCategory {
             id: category.id.clone(),
             name: category.name.clone(),
@@ -199,7 +201,7 @@ fn report_object(
             .unwrap_or_default(),
         auto_generated: object.metadata.as_ref().and_then(|m| m.auto_generated),
     };
-    let mut measures = Measures::default();
+    let mut measures = Measures { total_units: 1, ..Default::default() };
     let mut sections = vec![];
     let mut functions = vec![];
 
@@ -237,7 +239,7 @@ fn report_object(
         }
 
         for (symbol, symbol_diff) in section.symbols.iter().zip(&section_diff.symbols) {
-            if symbol.size == 0 {
+            if symbol.size == 0 || symbol.flags.0.contains(ObjSymbolFlags::Hidden) {
                 continue;
             }
             if let Some(existing_functions) = &mut existing_functions {
@@ -280,6 +282,7 @@ fn report_object(
     if metadata.complete.unwrap_or(false) {
         measures.complete_code = measures.total_code;
         measures.complete_data = measures.total_data;
+        measures.complete_units = 1;
     }
     measures.calc_fuzzy_match_percent();
     measures.calc_matched_percent();

objdiff-cli/src/main.rs

@@ -2,6 +2,12 @@ mod argp_version;
 mod cmd;
 mod util;
 
+// musl's allocator is very slow, so use mimalloc when targeting musl.
+// Otherwise, use the system allocator to avoid extra code size.
+#[cfg(target_env = "musl")]
+#[global_allocator]
+static ALLOC: mimalloc::MiMalloc = mimalloc::MiMalloc;
+
 use std::{env, ffi::OsStr, fmt::Display, path::PathBuf, str::FromStr};
 
 use anyhow::{Error, Result};

objdiff-core/Cargo.toml

@@ -17,8 +17,8 @@ crate-type = ["cdylib", "rlib"]
 
 [features]
 all = ["config", "dwarf", "mips", "ppc", "x86", "arm", "bindings"]
-any-arch = [] # Implicit, used to check if any arch is enabled
-config = ["globset", "semver", "serde_json", "serde_yaml"]
+any-arch = ["bimap"] # Implicit, used to check if any arch is enabled
+config = ["bimap", "globset", "semver", "serde_json", "serde_yaml"]
 dwarf = ["gimli"]
 mips = ["any-arch", "rabbitizer"]
 ppc = ["any-arch", "cwdemangle", "cwextab", "ppc750cl"]
@@ -27,8 +27,12 @@ arm = ["any-arch", "cpp_demangle", "unarm", "arm-attr"]
 bindings = ["serde_json", "prost", "pbjson"]
 wasm = ["bindings", "console_error_panic_hook", "console_log"]
 
+[package.metadata.docs.rs]
+features = ["all"]
+
 [dependencies]
 anyhow = "1.0"
+bimap = { version = "0.6", features = ["serde"], optional = true }
 byteorder = "1.5"
 filetime = "0.2"
 flagset = "0.4"
@@ -57,7 +61,7 @@ gimli = { version = "0.31", default-features = false, features = ["read-all"], o
 
 # ppc
 cwdemangle = { version = "1.0", optional = true }
-cwextab = { version = "0.2", optional = true }
+cwextab = { version = "1.0.2", optional = true }
 ppc750cl = { version = "0.3", optional = true }
 
 # mips

objdiff-core/protos/report.proto

@@ -32,6 +32,10 @@ message Measures {
   uint64 complete_data = 13;
   // Completed (or "linked") data percent
   float complete_data_percent = 14;
+  // Total number of units
+  uint32 total_units = 15;
+  // Completed (or "linked") units
+  uint32 complete_units = 16;
 }
 
 // Project progress report

objdiff-core/src/arch/mod.rs

@@ -1,11 +1,13 @@
-use std::{borrow::Cow, collections::BTreeMap};
+use std::{borrow::Cow, collections::BTreeMap, ffi::CStr};
 
 use anyhow::{bail, Result};
+use byteorder::ByteOrder;
 use object::{Architecture, File, Object, ObjectSymbol, Relocation, RelocationFlags, Symbol};
 
 use crate::{
     diff::DiffObjConfig,
     obj::{ObjIns, ObjReloc, ObjSection},
+    util::ReallySigned,
 };
 
 #[cfg(feature = "arm")]
@@ -17,6 +19,97 @@ pub mod ppc;
 #[cfg(feature = "x86")]
 pub mod x86;
 
+/// Represents the type of data associated with an instruction
+pub enum DataType {
+    Int8,
+    Int16,
+    Int32,
+    Int64,
+    Int128,
+    Float,
+    Double,
+    Bytes,
+    String,
+}
+
+impl DataType {
+    pub fn display_bytes<Endian: ByteOrder>(&self, bytes: &[u8]) -> Option<String> {
+        if self.required_len().is_some_and(|l| bytes.len() < l) {
+            return None;
+        }
+
+        match self {
+            DataType::Int8 => {
+                let i = i8::from_ne_bytes(bytes.try_into().unwrap());
+                if i < 0 {
+                    format!("Int8: {:#x} ({:#x})", i, ReallySigned(i))
+                } else {
+                    format!("Int8: {:#x}", i)
+                }
+            }
+            DataType::Int16 => {
+                let i = Endian::read_i16(bytes);
+                if i < 0 {
+                    format!("Int16: {:#x} ({:#x})", i, ReallySigned(i))
+                } else {
+                    format!("Int16: {:#x}", i)
+                }
+            }
+            DataType::Int32 => {
+                let i = Endian::read_i32(bytes);
+                if i < 0 {
+                    format!("Int32: {:#x} ({:#x})", i, ReallySigned(i))
+                } else {
+                    format!("Int32: {:#x}", i)
+                }
+            }
+            DataType::Int64 => {
+                let i = Endian::read_i64(bytes);
+                if i < 0 {
+                    format!("Int64: {:#x} ({:#x})", i, ReallySigned(i))
+                } else {
+                    format!("Int64: {:#x}", i)
+                }
+            }
+            DataType::Int128 => {
+                let i = Endian::read_i128(bytes);
+                if i < 0 {
+                    format!("Int128: {:#x} ({:#x})", i, ReallySigned(i))
+                } else {
+                    format!("Int128: {:#x}", i)
+                }
+            }
+            DataType::Float => {
+                format!("Float: {}", Endian::read_f32(bytes))
+            }
+            DataType::Double => {
+                format!("Double: {}", Endian::read_f64(bytes))
+            }
+            DataType::Bytes => {
+                format!("Bytes: {:#?}", bytes)
+            }
+            DataType::String => {
+                format!("String: {:?}", CStr::from_bytes_until_nul(bytes).ok()?)
+            }
+        }
+        .into()
+    }
+
+    fn required_len(&self) -> Option<usize> {
+        match self {
+            DataType::Int8 => Some(1),
+            DataType::Int16 => Some(2),
+            DataType::Int32 => Some(4),
+            DataType::Int64 => Some(8),
+            DataType::Int128 => Some(16),
+            DataType::Float => Some(4),
+            DataType::Double => Some(8),
+            DataType::Bytes => None,
+            DataType::String => None,
+        }
+    }
+}
+
 pub trait ObjArch: Send + Sync {
     fn process_code(
         &self,
@@ -42,6 +135,12 @@ pub trait ObjArch: Send + Sync {
 
     fn symbol_address(&self, symbol: &Symbol) -> u64 { symbol.address() }
 
+    fn guess_data_type(&self, _instruction: &ObjIns) -> Option<DataType> { None }
+
+    fn display_data_type(&self, _ty: DataType, bytes: &[u8]) -> Option<String> {
+        Some(format!("Bytes: {:#x?}", bytes))
+    }
+
     // Downcast methods
     #[cfg(feature = "ppc")]
     fn ppc(&self) -> Option<&ppc::ObjArchPpc> { None }

objdiff-core/src/arch/ppc.rs

@@ -1,15 +1,16 @@
 use std::{borrow::Cow, collections::BTreeMap};
 
 use anyhow::{bail, ensure, Result};
+use byteorder::BigEndian;
 use cwextab::{decode_extab, ExceptionTableData};
 use object::{
     elf, File, Object, ObjectSection, ObjectSymbol, Relocation, RelocationFlags, RelocationTarget,
     Symbol, SymbolKind,
 };
-use ppc750cl::{Argument, InsIter, GPR};
+use ppc750cl::{Argument, InsIter, Opcode, GPR};
 
 use crate::{
-    arch::{ObjArch, ProcessCodeResult},
+    arch::{DataType, ObjArch, ProcessCodeResult},
     diff::DiffObjConfig,
     obj::{ObjIns, ObjInsArg, ObjInsArgValue, ObjReloc, ObjSection, ObjSymbol},
 };
@@ -186,6 +187,34 @@ impl ObjArch for ObjArchPpc {
         }
     }
 
+    fn guess_data_type(&self, instruction: &ObjIns) -> Option<super::DataType> {
+        // Always shows the first string of the table. Not ideal, but it's really hard to find
+        // the actual string being referenced.
+        if instruction.reloc.as_ref().is_some_and(|r| r.target.name.starts_with("@stringBase")) {
+            return Some(DataType::String);
+        }
+
+        match Opcode::from(instruction.op as u8) {
+            Opcode::Lbz | Opcode::Lbzu | Opcode::Lbzux | Opcode::Lbzx => Some(DataType::Int8),
+            Opcode::Lhz | Opcode::Lhzu | Opcode::Lhzux | Opcode::Lhzx => Some(DataType::Int16),
+            Opcode::Lha | Opcode::Lhau | Opcode::Lhaux | Opcode::Lhax => Some(DataType::Int16),
+            Opcode::Lwz | Opcode::Lwzu | Opcode::Lwzux | Opcode::Lwzx => Some(DataType::Int32),
+            Opcode::Lfs | Opcode::Lfsu | Opcode::Lfsux | Opcode::Lfsx => Some(DataType::Float),
+            Opcode::Lfd | Opcode::Lfdu | Opcode::Lfdux | Opcode::Lfdx => Some(DataType::Double),
+
+            Opcode::Stb | Opcode::Stbu | Opcode::Stbux | Opcode::Stbx => Some(DataType::Int8),
+            Opcode::Sth | Opcode::Sthu | Opcode::Sthux | Opcode::Sthx => Some(DataType::Int16),
+            Opcode::Stw | Opcode::Stwu | Opcode::Stwux | Opcode::Stwx => Some(DataType::Int32),
+            Opcode::Stfs | Opcode::Stfsu | Opcode::Stfsux | Opcode::Stfsx => Some(DataType::Float),
+            Opcode::Stfd | Opcode::Stfdu | Opcode::Stfdux | Opcode::Stfdx => Some(DataType::Double),
+            _ => None,
+        }
+    }
+
+    fn display_data_type(&self, ty: DataType, bytes: &[u8]) -> Option<String> {
+        ty.display_bytes::<BigEndian>(bytes)
+    }
+
     fn ppc(&self) -> Option<&ObjArchPpc> { Some(self) }
 }
 
@@ -303,9 +332,13 @@ fn decode_exception_info(file: &File<'_>) -> Result<Option<BTreeMap<usize, Excep
             continue;
         };
         let data = match decode_extab(extab_data) {
-            Some(decoded_data) => decoded_data,
-            None => {
-                log::warn!("Exception table decoding failed for function {}", extab_func_name);
+            Ok(decoded_data) => decoded_data,
+            Err(e) => {
+                log::warn!(
+                    "Exception table decoding failed for function {}, reason: {}",
+                    extab_func_name,
+                    e.to_string()
+                );
                 return Ok(None);
             }
         };

objdiff-core/src/bindings/report.rs

@@ -8,9 +8,10 @@ use serde_json::error::Category;
 include!(concat!(env!("OUT_DIR"), "/objdiff.report.rs"));
 include!(concat!(env!("OUT_DIR"), "/objdiff.report.serde.rs"));
 
-pub const REPORT_VERSION: u32 = 1;
+pub const REPORT_VERSION: u32 = 2;
 
 impl Report {
+    /// Attempts to parse the report as binary protobuf or JSON.
     pub fn parse(data: &[u8]) -> Result<Self> {
         if data.is_empty() {
             bail!(std::io::Error::from(std::io::ErrorKind::UnexpectedEof));
@@ -25,6 +26,7 @@ impl Report {
         Ok(report)
     }
 
+    /// Attempts to parse the report as JSON, migrating from the legacy report format if necessary.
     fn from_json(bytes: &[u8]) -> Result<Self, serde_json::Error> {
         match serde_json::from_slice::<Self>(bytes) {
             Ok(report) => Ok(report),
@@ -43,16 +45,23 @@ impl Report {
         }
     }
 
+    /// Migrates the report to the latest version.
+    /// Fails if the report version is newer than supported.
     pub fn migrate(&mut self) -> Result<()> {
         if self.version == 0 {
             self.migrate_v0()?;
         }
+        if self.version == 1 {
+            self.migrate_v1()?;
+        }
         if self.version != REPORT_VERSION {
             bail!("Unsupported report version: {}", self.version);
         }
         Ok(())
     }
 
+    /// Adds `complete_code`, `complete_data`, `complete_code_percent`, and `complete_data_percent`
+    /// to measures, and sets `progress_categories` in unit metadata.
     fn migrate_v0(&mut self) -> Result<()> {
         let Some(measures) = &mut self.measures else {
             bail!("Missing measures in report");
@@ -61,15 +70,16 @@ impl Report {
             let Some(unit_measures) = &mut unit.measures else {
                 bail!("Missing measures in report unit");
             };
-            let Some(metadata) = &mut unit.metadata else {
-                bail!("Missing metadata in report unit");
+            let mut complete = false;
+            if let Some(metadata) = &mut unit.metadata {
+                if metadata.module_name.is_some() || metadata.module_id.is_some() {
+                    metadata.progress_categories = vec!["modules".to_string()];
+                } else {
+                    metadata.progress_categories = vec!["dol".to_string()];
+                }
+                complete = metadata.complete.unwrap_or(false);
             };
-            if metadata.module_name.is_some() || metadata.module_id.is_some() {
-                metadata.progress_categories = vec!["modules".to_string()];
-            } else {
-                metadata.progress_categories = vec!["dol".to_string()];
-            }
-            if metadata.complete.unwrap_or(false) {
+            if complete {
                 unit_measures.complete_code = unit_measures.total_code;
                 unit_measures.complete_data = unit_measures.total_data;
                 unit_measures.complete_code_percent = 100.0;
@@ -84,10 +94,42 @@ impl Report {
             measures.complete_data += unit_measures.complete_data;
         }
         measures.calc_matched_percent();
+        self.calculate_progress_categories();
         self.version = 1;
         Ok(())
     }
 
+    /// Adds `total_units` and `complete_units` to measures.
+    fn migrate_v1(&mut self) -> Result<()> {
+        let Some(total_measures) = &mut self.measures else {
+            bail!("Missing measures in report");
+        };
+        for unit in &mut self.units {
+            let Some(measures) = &mut unit.measures else {
+                bail!("Missing measures in report unit");
+            };
+            let complete = unit.metadata.as_ref().and_then(|m| m.complete).unwrap_or(false) as u32;
+            let progress_categories =
+                unit.metadata.as_ref().map(|m| m.progress_categories.as_slice()).unwrap_or(&[]);
+            measures.total_units = 1;
+            measures.complete_units = complete;
+            total_measures.total_units += 1;
+            total_measures.complete_units += complete;
+            for id in progress_categories {
+                if let Some(category) = self.categories.iter_mut().find(|c| &c.id == id) {
+                    let Some(measures) = &mut category.measures else {
+                        bail!("Missing measures in category");
+                    };
+                    measures.total_units += 1;
+                    measures.complete_units += complete;
+                }
+            }
+        }
+        self.version = 2;
+        Ok(())
+    }
+
+    /// Calculate progress categories based on unit metadata.
     pub fn calculate_progress_categories(&mut self) {
         for unit in &self.units {
             let Some(metadata) = unit.metadata.as_ref() else {
@@ -117,6 +159,72 @@ impl Report {
             measures.calc_matched_percent();
         }
     }
+
+    /// Split the report into multiple reports based on progress categories.
+    /// Assumes progress categories are in the format `version`, `version.category`.
+    /// This is a hack for projects that generate all versions in a single report.
+    pub fn split(self) -> Vec<(String, Report)> {
+        let mut reports = Vec::new();
+        // Map units to Option to allow taking ownership
+        let mut units = self.units.into_iter().map(Some).collect::<Vec<_>>();
+        for category in &self.categories {
+            if category.id.contains(".") {
+                // Skip subcategories
+                continue;
+            }
+            fn is_sub_category(id: &str, parent: &str, sep: char) -> bool {
+                id.starts_with(parent)
+                    && id.get(parent.len()..).map_or(false, |s| s.starts_with(sep))
+            }
+            let mut sub_categories = self
+                .categories
+                .iter()
+                .filter(|c| is_sub_category(&c.id, &category.id, '.'))
+                .cloned()
+                .collect::<Vec<_>>();
+            // Remove category prefix
+            for sub_category in &mut sub_categories {
+                sub_category.id = sub_category.id[category.id.len() + 1..].to_string();
+            }
+            let mut sub_units = units
+                .iter_mut()
+                .filter_map(|opt| {
+                    let unit = opt.as_mut()?;
+                    let metadata = unit.metadata.as_ref()?;
+                    if metadata.progress_categories.contains(&category.id) {
+                        opt.take()
+                    } else {
+                        None
+                    }
+                })
+                .collect::<Vec<_>>();
+            for sub_unit in &mut sub_units {
+                // Remove leading version/ from unit name
+                if let Some(name) =
+                    sub_unit.name.strip_prefix(&category.id).and_then(|s| s.strip_prefix('/'))
+                {
+                    sub_unit.name = name.to_string();
+                }
+                // Filter progress categories
+                let Some(metadata) = sub_unit.metadata.as_mut() else {
+                    continue;
+                };
+                metadata.progress_categories = metadata
+                    .progress_categories
+                    .iter()
+                    .filter(|c| is_sub_category(c, &category.id, '.'))
+                    .map(|c| c[category.id.len() + 1..].to_string())
+                    .collect();
+            }
+            reports.push((category.id.clone(), Report {
+                measures: category.measures,
+                units: sub_units,
+                version: self.version,
+                categories: sub_categories,
+            }));
+        }
+        reports
+    }
 }
 
 impl Measures {
@@ -176,6 +284,8 @@ impl AddAssign for Measures {
         self.matched_functions += other.matched_functions;
         self.complete_code += other.complete_code;
         self.complete_data += other.complete_data;
+        self.total_units += other.total_units;
+        self.complete_units += other.complete_units;
     }
 }
 

objdiff-core/src/config/mod.rs

@@ -1,77 +1,100 @@
 use std::{
+    fs,
     fs::File,
-    io::Read,
+    io::{BufReader, BufWriter, Read},
     path::{Path, PathBuf},
 };
 
 use anyhow::{anyhow, Context, Result};
+use bimap::BiBTreeMap;
 use filetime::FileTime;
 use globset::{Glob, GlobSet, GlobSetBuilder};
 
-#[inline]
-fn bool_true() -> bool { true }
-
-#[derive(Default, Clone, serde::Deserialize)]
+#[derive(Default, Clone, serde::Serialize, serde::Deserialize)]
 pub struct ProjectConfig {
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub min_version: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub custom_make: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub custom_args: Option<Vec<String>>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub target_dir: Option<PathBuf>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub base_dir: Option<PathBuf>,
-    #[serde(default = "bool_true")]
-    pub build_base: bool,
-    #[serde(default)]
-    pub build_target: bool,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub build_base: Option<bool>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub build_target: Option<bool>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub watch_patterns: Option<Vec<Glob>>,
-    #[serde(default, alias = "units")]
-    pub objects: Vec<ProjectObject>,
-    #[serde(default)]
-    pub progress_categories: Vec<ProjectProgressCategory>,
+    #[serde(default, alias = "objects", skip_serializing_if = "Option::is_none")]
+    pub units: Option<Vec<ProjectObject>>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub progress_categories: Option<Vec<ProjectProgressCategory>>,
 }
 
-#[derive(Default, Clone, serde::Deserialize)]
+impl ProjectConfig {
+    #[inline]
+    pub fn units(&self) -> &[ProjectObject] { self.units.as_deref().unwrap_or_default() }
+
+    #[inline]
+    pub fn units_mut(&mut self) -> &mut Vec<ProjectObject> {
+        self.units.get_or_insert_with(Vec::new)
+    }
+
+    #[inline]
+    pub fn progress_categories(&self) -> &[ProjectProgressCategory] {
+        self.progress_categories.as_deref().unwrap_or_default()
+    }
+
+    #[inline]
+    pub fn progress_categories_mut(&mut self) -> &mut Vec<ProjectProgressCategory> {
+        self.progress_categories.get_or_insert_with(Vec::new)
+    }
+}
+
+#[derive(Default, Clone, serde::Serialize, serde::Deserialize)]
 pub struct ProjectObject {
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub name: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub path: Option<PathBuf>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub target_path: Option<PathBuf>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub base_path: Option<PathBuf>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     #[deprecated(note = "Use metadata.reverse_fn_order")]
     pub reverse_fn_order: Option<bool>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     #[deprecated(note = "Use metadata.complete")]
     pub complete: Option<bool>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub scratch: Option<ScratchConfig>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub metadata: Option<ProjectObjectMetadata>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub symbol_mappings: Option<SymbolMappings>,
 }
 
-#[derive(Default, Clone, serde::Deserialize)]
+pub type SymbolMappings = BiBTreeMap<String, String>;
+
+#[derive(Default, Clone, serde::Serialize, serde::Deserialize)]
 pub struct ProjectObjectMetadata {
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub complete: Option<bool>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub reverse_fn_order: Option<bool>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub source_path: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub progress_categories: Option<Vec<String>>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub auto_generated: Option<bool>,
 }
 
-#[derive(Default, Clone, serde::Deserialize)]
+#[derive(Default, Clone, serde::Serialize, serde::Deserialize)]
 pub struct ProjectProgressCategory {
     #[serde(default)]
     pub id: String,
@@ -112,32 +135,36 @@ impl ProjectObject {
     }
 
     pub fn complete(&self) -> Option<bool> {
-        #[allow(deprecated)]
+        #[expect(deprecated)]
         self.metadata.as_ref().and_then(|m| m.complete).or(self.complete)
     }
 
     pub fn reverse_fn_order(&self) -> Option<bool> {
-        #[allow(deprecated)]
+        #[expect(deprecated)]
         self.metadata.as_ref().and_then(|m| m.reverse_fn_order).or(self.reverse_fn_order)
     }
 
     pub fn hidden(&self) -> bool {
         self.metadata.as_ref().and_then(|m| m.auto_generated).unwrap_or(false)
     }
+
+    pub fn source_path(&self) -> Option<&String> {
+        self.metadata.as_ref().and_then(|m| m.source_path.as_ref())
+    }
 }
 
 #[derive(Default, Clone, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
 pub struct ScratchConfig {
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub platform: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub compiler: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub c_flags: Option<String>,
-    #[serde(default)]
+    #[serde(default, skip_serializing_if = "Option::is_none")]
     pub ctx_path: Option<PathBuf>,
-    #[serde(default)]
-    pub build_ctx: bool,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub build_ctx: Option<bool>,
 }
 
 pub const CONFIG_FILENAMES: [&str; 3] = ["objdiff.json", "objdiff.yml", "objdiff.yaml"];
@@ -150,13 +177,13 @@ pub const DEFAULT_WATCH_PATTERNS: &[&str] = &[
 #[derive(Clone, Eq, PartialEq)]
 pub struct ProjectConfigInfo {
     pub path: PathBuf,
-    pub timestamp: FileTime,
+    pub timestamp: Option<FileTime>,
 }
 
 pub fn try_project_config(dir: &Path) -> Option<(Result<ProjectConfig>, ProjectConfigInfo)> {
     for filename in CONFIG_FILENAMES.iter() {
         let config_path = dir.join(filename);
-        let Ok(mut file) = File::open(&config_path) else {
+        let Ok(file) = File::open(&config_path) else {
             continue;
         };
         let metadata = file.metadata();
@@ -165,9 +192,10 @@ pub fn try_project_config(dir: &Path) -> Option<(Result<ProjectConfig>, ProjectC
                 continue;
             }
             let ts = FileTime::from_last_modification_time(&metadata);
+            let mut reader = BufReader::new(file);
             let mut result = match filename.contains("json") {
-                true => read_json_config(&mut file),
-                false => read_yml_config(&mut file),
+                true => read_json_config(&mut reader),
+                false => read_yml_config(&mut reader),
             };
             if let Ok(config) = &result {
                 // Validate min_version if present
@@ -175,12 +203,41 @@ pub fn try_project_config(dir: &Path) -> Option<(Result<ProjectConfig>, ProjectC
                     result = Err(e);
                 }
             }
-            return Some((result, ProjectConfigInfo { path: config_path, timestamp: ts }));
+            return Some((result, ProjectConfigInfo { path: config_path, timestamp: Some(ts) }));
         }
     }
     None
 }
 
+pub fn save_project_config(
+    config: &ProjectConfig,
+    info: &ProjectConfigInfo,
+) -> Result<ProjectConfigInfo> {
+    if let Some(last_ts) = info.timestamp {
+        // Check if the file has changed since we last read it
+        if let Ok(metadata) = fs::metadata(&info.path) {
+            let ts = FileTime::from_last_modification_time(&metadata);
+            if ts != last_ts {
+                return Err(anyhow!("Config file has changed since last read"));
+            }
+        }
+    }
+    let mut writer =
+        BufWriter::new(File::create(&info.path).context("Failed to create config file")?);
+    let ext = info.path.extension().and_then(|ext| ext.to_str()).unwrap_or("json");
+    match ext {
+        "json" => serde_json::to_writer_pretty(&mut writer, config).context("Failed to write JSON"),
+        "yml" | "yaml" => {
+            serde_yaml::to_writer(&mut writer, config).context("Failed to write YAML")
+        }
+        _ => Err(anyhow!("Unknown config file extension: {ext}")),
+    }?;
+    let file = writer.into_inner().context("Failed to flush file")?;
+    let metadata = file.metadata().context("Failed to get file metadata")?;
+    let ts = FileTime::from_last_modification_time(&metadata);
+    Ok(ProjectConfigInfo { path: info.path.clone(), timestamp: Some(ts) })
+}
+
 fn validate_min_version(config: &ProjectConfig) -> Result<()> {
     let Some(min_version) = &config.min_version else { return Ok(()) };
     let version = semver::Version::parse(env!("CARGO_PKG_VERSION"))

objdiff-core/src/diff/code.rs

@@ -41,7 +41,7 @@ pub fn no_diff_code(out: &ProcessCodeResult, symbol_ref: SymbolRef) -> Result<Ob
         });
     }
     resolve_branches(&mut diff);
-    Ok(ObjSymbolDiff { symbol_ref, diff_symbol: None, instructions: diff, match_percent: None })
+    Ok(ObjSymbolDiff { symbol_ref, target_symbol: None, instructions: diff, match_percent: None })
 }
 
 pub fn diff_code(
@@ -67,7 +67,7 @@ pub fn diff_code(
         right.arg_diff = result.right_args_diff;
     }
 
-    let total = left_out.insts.len();
+    let total = left_out.insts.len().max(right_out.insts.len());
     let percent = if diff_state.diff_count >= total {
         0.0
     } else {
@@ -77,13 +77,13 @@ pub fn diff_code(
     Ok((
         ObjSymbolDiff {
             symbol_ref: left_symbol_ref,
-            diff_symbol: Some(right_symbol_ref),
+            target_symbol: Some(right_symbol_ref),
             instructions: left_diff,
             match_percent: Some(percent),
         },
         ObjSymbolDiff {
             symbol_ref: right_symbol_ref,
-            diff_symbol: Some(left_symbol_ref),
+            target_symbol: Some(left_symbol_ref),
             instructions: right_diff,
             match_percent: Some(percent),
         },
@@ -211,7 +211,7 @@ fn arg_eq(
     left_diff: &ObjInsDiff,
     right_diff: &ObjInsDiff,
 ) -> bool {
-    return match left {
+    match left {
         ObjInsArg::PlainText(l) => match right {
             ObjInsArg::PlainText(r) => l == r,
             _ => false,
@@ -236,7 +236,7 @@ fn arg_eq(
             left_diff.branch_to.as_ref().map(|b| b.ins_idx)
                 == right_diff.branch_to.as_ref().map(|b| b.ins_idx)
         }
-    };
+    }
 }
 
 #[derive(Default)]

objdiff-core/src/diff/data.rs

@@ -20,13 +20,13 @@ pub fn diff_bss_symbol(
     Ok((
         ObjSymbolDiff {
             symbol_ref: left_symbol_ref,
-            diff_symbol: Some(right_symbol_ref),
+            target_symbol: Some(right_symbol_ref),
             instructions: vec![],
             match_percent: Some(percent),
         },
         ObjSymbolDiff {
             symbol_ref: right_symbol_ref,
-            diff_symbol: Some(left_symbol_ref),
+            target_symbol: Some(left_symbol_ref),
             instructions: vec![],
             match_percent: Some(percent),
         },
@@ -34,7 +34,7 @@ pub fn diff_bss_symbol(
 }
 
 pub fn no_diff_symbol(_obj: &ObjInfo, symbol_ref: SymbolRef) -> ObjSymbolDiff {
-    ObjSymbolDiff { symbol_ref, diff_symbol: None, instructions: vec![], match_percent: None }
+    ObjSymbolDiff { symbol_ref, target_symbol: None, instructions: vec![], match_percent: None }
 }
 
 /// Compare the data sections of two object files.
@@ -158,13 +158,13 @@ pub fn diff_data_symbol(
     Ok((
         ObjSymbolDiff {
             symbol_ref: left_symbol_ref,
-            diff_symbol: Some(right_symbol_ref),
+            target_symbol: Some(right_symbol_ref),
             instructions: vec![],
             match_percent: Some(match_percent),
         },
         ObjSymbolDiff {
             symbol_ref: right_symbol_ref,
-            diff_symbol: Some(left_symbol_ref),
+            target_symbol: Some(left_symbol_ref),
             instructions: vec![],
             match_percent: Some(match_percent),
         },

objdiff-core/src/diff/display.rs

@@ -29,7 +29,7 @@ pub enum DiffText<'a> {
     Eol,
 }
 
-#[derive(Default, Clone, PartialEq, Eq)]
+#[derive(Debug, Default, Clone, PartialEq, Eq)]
 pub enum HighlightKind {
     #[default]
     None,