Use Rc<RefCell<T>>> for content_records so that they sync in a Title

When using a Title, the content_records value stored in the TMD and ContentRegion instances will now point to the same data, meaning that they stay in sync. Previously, you had to manually sync the content records between them as they were modified, and not doing so would cause problems when editing a WAD.
Added rustii CLI commands to add and remove content from a WAD
2025-06-07 07:51:01 -04:00 · 2025-04-27 21:30:31 -04:00 · 2025-04-27 15:25:47 -04:00
11 changed files with 322 additions and 106 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@ -921,7 +921,7 @@ dependencies = [
 "num-integer",
 "num-iter",
 "num-traits",
- "rand",
+ "rand 0.8.5",
 "smallvec",
 "zeroize",
 ]
@ -1108,8 +1108,18 @@ version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
 dependencies = [
- "rand_chacha",
- "rand_core",
+ "rand_chacha 0.3.1",
+ "rand_core 0.6.4",
+]
+
+[[package]]
+name = "rand"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9fbfd9d094a40bf3ae768db9361049ace4c0e04a4fd6b359518bd7b73a73dd97"
+dependencies = [
+ "rand_chacha 0.9.0",
+ "rand_core 0.9.3",
 ]

 [[package]]
@ -1119,7 +1129,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
 dependencies = [
 "ppv-lite86",
- "rand_core",
+ "rand_core 0.6.4",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3022b5f1df60f26e1ffddd6c66e8aa15de382ae63b3a0c1bfc0e4d3e3f325cb"
+dependencies = [
+ "ppv-lite86",
+ "rand_core 0.9.3",
 ]

 [[package]]
@ -1131,6 +1151,15 @@ dependencies = [
 "getrandom 0.2.15",
 ]

+[[package]]
+name = "rand_core"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "99d9a13982dcf210057a8a78572b2217b667c3beacbf3a0d8b454f6f82837d38"
+dependencies = [
+ "getrandom 0.3.2",
+]
+
 [[package]]
 name = "regex"
 version = "1.11.1"
@ -1232,7 +1261,7 @@ dependencies = [
 "num-traits",
 "pkcs1",
 "pkcs8",
- "rand_core",
+ "rand_core 0.6.4",
 "sha2",
 "signature",
 "spki",
@ -1257,6 +1286,7 @@ dependencies = [
 "clap",
 "glob",
 "hex",
+ "rand 0.9.1",
 "regex",
 "reqwest",
 "rsa",
@ -1439,7 +1469,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "77549399552de45a898a580c1b41d445bf730df867cc44e6c0233bbc4b8329de"
 dependencies = [
 "digest",
- "rand_core",
+ "rand_core 0.6.4",
 ]

 [[package]]
--- a/Cargo.toml
+++ b/Cargo.toml
@ -36,3 +36,4 @@ clap = { version = "4", features = ["derive"] }
 anyhow = "1"
 thiserror = "2"
 reqwest = { version = "0", features = ["blocking"] }
+rand = "0"
--- a/src/bin/playground/main.rs
+++ b/src/bin/playground/main.rs
@ -11,8 +11,8 @@ fn main() {
    
    let wad = wad::WAD::from_bytes(&data).unwrap();
    println!("size of tmd: {:?}", wad.tmd().len());
-    println!("num content records: {:?}", title.tmd.content_records.len());
-    println!("first record data: {:?}", title.tmd.content_records.first().unwrap());
+    println!("num content records: {:?}", title.tmd.content_records.borrow().len());
+    println!("first record data: {:?}", title.tmd.content_records.borrow().first().unwrap());
    println!("TMD is fakesigned: {:?}",title.tmd.is_fakesigned());
    
    println!("title version from ticket is: {:?}", title.ticket.title_version);
--- a/src/bin/rustii/info.rs
+++ b/src/bin/rustii/info.rs
@ -117,10 +117,10 @@ fn print_tmd_info(tmd: tmd::TMD, cert: Option<cert::Certificate>) -> Result<()>
        println!("  Fakesigned: {}", tmd.is_fakesigned());
    }
    println!("\nContent Info");
-    println!("  Total Contents: {}", tmd.num_contents);
+    println!("  Total Contents: {}", tmd.content_records.borrow().len());
    println!("  Boot Content Index: {}", tmd.boot_index);
    println!("  Content Records:");
-    for content in tmd.content_records {
+    for content in tmd.content_records.borrow().iter() {
        println!("    Content Index: {}", content.index);
        println!("      Content ID: {:08X}", content.content_id);
        println!("      Content Type: {}", content.content_type);
--- a/src/bin/rustii/main.rs
+++ b/src/bin/rustii/main.rs
@ -119,18 +119,24 @@ fn main() -> Result<()> {
        },
        Some(Commands::Wad { command }) => {
            match command {
+                title::wad::Commands::Add { input, content, output, cid, r#type } => {
+                    title::wad::add_wad(input, content, output, cid, r#type)?
+                },
                title::wad::Commands::Convert { input, target, output } => {
                    title::wad::convert_wad(input, target, output)?
                },
                title::wad::Commands::Pack { input, output} => {
                    title::wad::pack_wad(input, output)?
                },
-                title::wad::Commands::Unpack { input, output } => {
-                    title::wad::unpack_wad(input, output)?
+                title::wad::Commands::Remove { input, output, identifier } => {
+                    title::wad::remove_wad(input, output, identifier)?
                },
                title::wad::Commands::Set { input, content, output, identifier, r#type} => {
                    title::wad::set_wad(input, content, output, identifier, r#type)?
-                }
+                },
+                title::wad::Commands::Unpack { input, output } => {
+                    title::wad::unpack_wad(input, output)?
+                },
            }
        },
        None => { /* Clap handles no passed command by itself */}
--- a/src/bin/rustii/title/nus.rs
+++ b/src/bin/rustii/title/nus.rs
@ -109,7 +109,7 @@ pub fn download_content(tid: &str, cid: &str, version: &Option<String>, output:
            Err(_) => bail!("No Ticket is available for this title! The content cannot be decrypted.")
        };
        println!(" - Decrypting content...");
-        let (content_hash, content_size, content_index) = tmd.content_records.iter()
+        let (content_hash, content_size, content_index) = tmd.content_records.borrow().iter()
            .find(|record| record.content_id == cid)
            .map(|record| (record.content_hash, record.content_size, record.index))
            .with_context(|| "No matching content record could be found. Please make sure the requested content is from the specified title version.")?;
@ -167,7 +167,7 @@ fn download_title_dir(title: title::Title, output: String) -> Result<()> {
    println!("  - Saving certificate chain...");
    fs::write(out_path.join(format!("{}.cert", &tid)), title.cert_chain.to_bytes()?).with_context(|| format!("Failed to open certificate chain file \"{}.cert\" for writing.", tid))?;
    // Iterate over the content files and write them out in encrypted form.
-    for record in &title.content.content_records {
+    for record in title.content.content_records.borrow().iter() {
        println!("  - Decrypting and saving content with Content ID {}...", record.content_id);
        fs::write(out_path.join(format!("{:08X}.app", record.content_id)), title.get_content_by_cid(record.content_id)?)
            .with_context(|| format!("Failed to open content file \"{:08X}.app\" for writing.", record.content_id))?;
@ -192,7 +192,7 @@ fn download_title_dir_enc(tmd: tmd::TMD, content_region: content::ContentRegion,
    println!("  - Saving certificate chain...");
    fs::write(out_path.join(format!("{}.cert", &tid)), cert_chain.to_bytes()?).with_context(|| format!("Failed to open certificate chain file \"{}.cert\" for writing.", tid))?;
    // Iterate over the content files and write them out in encrypted form.
-    for record in &content_region.content_records {
+    for record in content_region.content_records.borrow().iter() {
        println!("  - Saving content with Content ID {}...", record.content_id);
        fs::write(out_path.join(format!("{:08X}", record.content_id)), content_region.get_enc_content_by_cid(record.content_id)?)
            .with_context(|| format!("Failed to open content file \"{:08X}\" for writing.", record.content_id))?;
@ -241,9 +241,9 @@ pub fn download_title(tid: &str, version: &Option<String>, output: &TitleOutputT
    };
    // Build a vec of contents by iterating over the content records and downloading each one.
    let mut contents: Vec<Vec<u8>> = Vec::new();
-    for record in &tmd.content_records {
+    for record in tmd.content_records.borrow().iter() {
        println!(" - Downloading content {} of {} (Content ID: {}, Size: {} bytes)...",
-            record.index + 1, &tmd.content_records.len(), record.content_id, record.content_size);
+            record.index + 1, &tmd.content_records.borrow().len(), record.content_id, record.content_size);
        contents.push(nus::download_content(tid, record.content_id, true).with_context(|| format!("Content with Content ID {} could not be downloaded.", record.content_id))?);
        println!("   - Done!");
    }
--- a/src/bin/rustii/title/wad.rs
+++ b/src/bin/rustii/title/wad.rs
@ -8,12 +8,30 @@ use std::path::{Path, PathBuf};
 use anyhow::{bail, Context, Result};
 use clap::{Subcommand, Args};
 use glob::glob;
+use rand::prelude::*;
 use rustii::title::{cert, crypto, tmd, ticket, content, wad};
 use rustii::title;

 #[derive(Subcommand)]
 #[command(arg_required_else_help = true)]
 pub enum Commands {
+    /// Add new content to a WAD file
+    Add {
+        /// The path to the WAD file to modify
+        input: String,
+        /// The path to the new content to add
+        content: String,
+        /// An optional output path; defaults to overwriting input WAD file
+        #[arg(short, long)]
+        output: Option<String>,
+        /// An optional Content ID for the new content; defaults to being randomly assigned
+        #[arg(short, long)]
+        cid: Option<String>,
+        /// An optional type for the new content, can be "Normal", "Shared", or "DLC"; defaults to
+        /// "Normal"
+        #[arg(short, long)]
+        r#type: Option<String>,
+    },
    /// Re-encrypt a WAD file with a different key
    Convert {
        /// The path to the WAD to convert
@ -31,18 +49,21 @@ pub enum Commands {
        /// The name of the packed WAD file
        output: String
    },
-    /// Unpack a WAD file into a directory
-    Unpack {
-        /// The path to the WAD to unpack
+    /// Remove content from a WAD file
+    Remove {
+        /// The path to the WAD file to modify
        input: String,
-        /// The directory to extract the WAD to
-        output: String
+        /// An optional output path; defaults to overwriting input WAD file
+        #[arg(short, long)]
+        output: Option<String>,
+        #[command(flatten)]
+        identifier: ContentIdentifier,
    },
    /// Replace existing content in a WAD file with new data
    Set {
        /// The path to the WAD file to modify
        input: String,
-        /// The new WAD content
+        /// The path to the new content to set
        content: String,
        /// An optional output path; defaults to overwriting input WAD file
        #[arg(short, long)]
@ -52,7 +73,14 @@ pub enum Commands {
        r#type: Option<String>,
        #[command(flatten)]
        identifier: ContentIdentifier,
-    }
+    },
+    /// Unpack a WAD file into a directory
+    Unpack {
+        /// The path to the WAD to unpack
+        input: String,
+        /// The directory to extract the WAD to
+        output: String
+    },
 }

 #[derive(Args)]
@ -74,10 +102,10 @@ pub struct ConvertTargets {
 #[clap(next_help_heading = "Content Identifier")]
 #[group(multiple = false, required = true)]
 pub struct ContentIdentifier {
-    /// The index of the content to replace
+    /// The index of the target content
    #[arg(short, long)]
    index: Option<usize>,
-    /// The Content ID of the content to replace
+    /// The Content ID of the target content
    #[arg(short, long)]
    cid: Option<String>,
 }
@ -98,6 +126,60 @@ impl fmt::Display for Target {
    }
 }

+pub fn add_wad(input: &str, content: &str, output: &Option<String>, cid: &Option<String>, ctype: &Option<String>) -> Result<()> {
+    let in_path = Path::new(input);
+    if !in_path.exists() {
+        bail!("Source WAD \"{}\" could not be found.", in_path.display());
+    }
+    let content_path = Path::new(content);
+    if !content_path.exists() {
+        bail!("New content \"{}\" could not be found.", content_path.display());
+    }
+    let out_path = if output.is_some() {
+        PathBuf::from(output.clone().unwrap()).with_extension("wad")
+    } else {
+        in_path.to_path_buf()
+    };
+    // Load the WAD and parse the target type and Content ID.
+    let mut title = title::Title::from_bytes(&fs::read(in_path)?).with_context(|| "The provided WAD file could not be parsed, and is likely invalid.")?;
+    let new_content = fs::read(content_path)?;
+    let target_type = if ctype.is_some() {
+        match ctype.clone().unwrap().to_ascii_lowercase().as_str() {
+            "normal" => tmd::ContentType::Normal,
+            "shared" => tmd::ContentType::Shared,
+            "dlc" => tmd::ContentType::DLC,
+            _ => bail!("The specified content type \"{}\" is invalid!", ctype.clone().unwrap()),
+        }
+    } else {
+        println!("Using default type \"Normal\" because no content type was specified.");
+        tmd::ContentType::Normal
+    };
+    let target_cid = if cid.is_some() {
+        let cid = u32::from_str_radix(cid.clone().unwrap().as_str(), 16).with_context(|| "The specified Content ID is invalid!")?;
+        if title.content.content_records.borrow().iter().any(|record| record.content_id == cid) {
+            bail!("The specified Content ID \"{:08X}\" is already being used in this WAD!", cid);
+        }
+        cid
+    } else {
+        // Generate a random CID if one wasn't specified, and ensure that it isn't already in use.
+        let mut rng = rand::rng();
+        let mut cid: u32;
+        loop {
+            cid = rng.random_range(0..=0xFF);
+            if !title.content.content_records.borrow().iter().any(|record| record.content_id == cid) {
+                break;
+            }
+        }
+        println!("Generated new random Content ID \"{:08X}\" ({}) because no Content ID was specified.", cid, cid);
+        cid
+    };
+    title.add_content(&new_content, target_cid, target_type.clone()).with_context(|| "An unknown error occurred while setting the new content.")?;
+    title.fakesign().with_context(|| "An unknown error occurred while fakesigning the modified WAD.")?;
+    fs::write(&out_path, title.to_wad()?.to_bytes()?).with_context(|| "Could not open output file for writing.")?;
+    println!("Successfully added new content with Content ID \"{:08X}\" ({}) and type \"{}\" to WAD file \"{}\"!", target_cid, target_cid, target_type, out_path.display());
+    Ok(())
+}
+
 pub fn convert_wad(input: &str, target: &ConvertTargets, output: &Option<String>) -> Result<()> {
    let in_path = Path::new(input);
    if !in_path.exists() {
@ -214,7 +296,7 @@ pub fn pack_wad(input: &str, output: &str) -> Result<()> {
    }
    // Iterate over expected content and read it into a content region.
    let mut content_region = content::ContentRegion::new(tmd.content_records.clone())?;
-    for content in tmd.content_records.clone() {
+    for content in tmd.content_records.borrow().iter() {
        let data = fs::read(format!("{}/{:08X}.app", in_path.display(), content.index)).with_context(|| format!("Could not open content file \"{:08X}.app\" for reading.", content.index))?;
        content_region.set_content(&data, content.index as usize, None, None, tik.dec_title_key())
            .with_context(|| "Failed to load content into the ContentRegion.")?;
@ -239,35 +321,37 @@ pub fn pack_wad(input: &str, output: &str) -> Result<()> {
    Ok(())
 }

-pub fn unpack_wad(input: &str, output: &str) -> Result<()> {
+pub fn remove_wad(input: &str, output: &Option<String>, identifier: &ContentIdentifier) ->  Result<()> {
    let in_path = Path::new(input);
    if !in_path.exists() {
-        bail!("Source WAD \"{}\" could not be found.", input);
+        bail!("Source WAD \"{}\" could not be found.", in_path.display());
    }
-    let wad_file = fs::read(in_path).with_context(|| format!("Failed to open WAD file \"{}\" for reading.", in_path.display()))?;
-    let title = title::Title::from_bytes(&wad_file).with_context(|| format!("The provided WAD file \"{}\" appears to be invalid.", in_path.display()))?;
-    let tid = hex::encode(title.tmd.title_id);
-    // Create output directory if it doesn't exist.
-    let out_path = Path::new(output);
-    if !out_path.exists() {
-        fs::create_dir(out_path).with_context(|| format!("The output directory \"{}\" could not be created.", out_path.display()))?;
+    let out_path = if output.is_some() {
+        PathBuf::from(output.clone().unwrap()).with_extension("wad")
+    } else {
+        in_path.to_path_buf()
+    };
+    let mut title = title::Title::from_bytes(&fs::read(in_path)?).with_context(|| "The provided WAD file could not be parsed, and is likely invalid.")?;
+    // Parse the identifier passed to choose how to find and remove the target.
+    // ...maybe don't take the above comment out of context
+    if identifier.index.is_some() {
+        title.content.remove_content(identifier.index.unwrap()).with_context(|| "The specified index does not exist in the provided WAD!")?;
+        println!("{:?}", title.tmd);
+        title.fakesign().with_context(|| "An unknown error occurred while fakesigning the modified WAD.")?;
+        fs::write(&out_path, title.to_wad()?.to_bytes()?).with_context(|| "Could not open output file for writing.")?;
+        println!("Successfully removed content at index {} in WAD file \"{}\".", identifier.index.unwrap(), out_path.display());
+    } else if identifier.cid.is_some() {
+        let cid = u32::from_str_radix(identifier.cid.clone().unwrap().as_str(), 16).with_context(|| "The specified Content ID is invalid!")?;
+        let index = match title.content.get_index_from_cid(cid) {
+            Ok(index) => index,
+            Err(_) => bail!("The specified Content ID \"{}\" ({}) does not exist in this WAD!", identifier.cid.clone().unwrap(), cid),
+        };
+        title.content.remove_content(index).with_context(|| "An unknown error occurred while removing content from the WAD.")?;
+        println!("{:?}", title.tmd);
+        title.fakesign().with_context(|| "An unknown error occurred while fakesigning the modified WAD.")?;
+        fs::write(&out_path, title.to_wad()?.to_bytes()?).with_context(|| "Could not open output file for writing.")?;
+        println!("Successfully removed content with Content ID \"{}\" ({}) in WAD file \"{}\".", identifier.cid.clone().unwrap(), cid, out_path.display());
    }
-    // Write out all WAD components.
-    let tmd_file_name = format!("{}.tmd", tid);
-    fs::write(Path::join(out_path, tmd_file_name.clone()), title.tmd.to_bytes()?).with_context(|| format!("Failed to open TMD file \"{}\" for writing.", tmd_file_name))?;
-    let ticket_file_name = format!("{}.tik", tid);
-    fs::write(Path::join(out_path, ticket_file_name.clone()), title.ticket.to_bytes()?).with_context(|| format!("Failed to open Ticket file \"{}\" for writing.", ticket_file_name))?;
-    let cert_file_name = format!("{}.cert", tid);
-    fs::write(Path::join(out_path, cert_file_name.clone()), title.cert_chain.to_bytes()?).with_context(|| format!("Failed to open certificate chain file \"{}\" for writing.", cert_file_name))?;
-    let meta_file_name = format!("{}.footer", tid);
-    fs::write(Path::join(out_path, meta_file_name.clone()), title.meta()).with_context(|| format!("Failed to open footer file \"{}\" for writing.", meta_file_name))?;
-    // Iterate over contents, decrypt them, and write them out.
-    for i in 0..title.tmd.num_contents {
-        let content_file_name = format!("{:08X}.app", title.content.content_records[i as usize].index);
-        let dec_content = title.get_content_by_index(i as usize).with_context(|| format!("Failed to unpack content with Content ID {:08X}.", title.content.content_records[i as usize].content_id))?;
-        fs::write(Path::join(out_path, content_file_name), dec_content).with_context(|| format!("Failed to open content file \"{:08X}.app\" for writing.", title.content.content_records[i as usize].content_id))?;
-    }
-    println!("WAD file unpacked!");
    Ok(())
 }

@ -280,7 +364,6 @@ pub fn set_wad(input: &str, content: &str, output: &Option<String>, identifier:
    if !content_path.exists() {
        bail!("New content \"{}\" could not be found.", content_path.display());
    }
-    // Get the output name now that we know the target, if one wasn't passed.
    let out_path = if output.is_some() {
        PathBuf::from(output.clone().unwrap()).with_extension("wad")
    } else {
@ -323,3 +406,35 @@ pub fn set_wad(input: &str, content: &str, output: &Option<String>, identifier:
    }
    Ok(())
 }
+
+pub fn unpack_wad(input: &str, output: &str) -> Result<()> {
+    let in_path = Path::new(input);
+    if !in_path.exists() {
+        bail!("Source WAD \"{}\" could not be found.", input);
+    }
+    let wad_file = fs::read(in_path).with_context(|| format!("Failed to open WAD file \"{}\" for reading.", in_path.display()))?;
+    let title = title::Title::from_bytes(&wad_file).with_context(|| format!("The provided WAD file \"{}\" appears to be invalid.", in_path.display()))?;
+    let tid = hex::encode(title.tmd.title_id);
+    // Create output directory if it doesn't exist.
+    let out_path = Path::new(output);
+    if !out_path.exists() {
+        fs::create_dir(out_path).with_context(|| format!("The output directory \"{}\" could not be created.", out_path.display()))?;
+    }
+    // Write out all WAD components.
+    let tmd_file_name = format!("{}.tmd", tid);
+    fs::write(Path::join(out_path, tmd_file_name.clone()), title.tmd.to_bytes()?).with_context(|| format!("Failed to open TMD file \"{}\" for writing.", tmd_file_name))?;
+    let ticket_file_name = format!("{}.tik", tid);
+    fs::write(Path::join(out_path, ticket_file_name.clone()), title.ticket.to_bytes()?).with_context(|| format!("Failed to open Ticket file \"{}\" for writing.", ticket_file_name))?;
+    let cert_file_name = format!("{}.cert", tid);
+    fs::write(Path::join(out_path, cert_file_name.clone()), title.cert_chain.to_bytes()?).with_context(|| format!("Failed to open certificate chain file \"{}\" for writing.", cert_file_name))?;
+    let meta_file_name = format!("{}.footer", tid);
+    fs::write(Path::join(out_path, meta_file_name.clone()), title.meta()).with_context(|| format!("Failed to open footer file \"{}\" for writing.", meta_file_name))?;
+    // Iterate over contents, decrypt them, and write them out.
+    for i in 0..title.tmd.content_records.borrow().len() {
+        let content_file_name = format!("{:08X}.app", title.content.content_records.borrow()[i].index);
+        let dec_content = title.get_content_by_index(i).with_context(|| format!("Failed to unpack content with Content ID {:08X}.", title.content.content_records.borrow()[i].content_id))?;
+        fs::write(Path::join(out_path, content_file_name), dec_content).with_context(|| format!("Failed to open content file \"{:08X}.app\" for writing.", title.content.content_records.borrow()[i].content_id))?;
+    }
+    println!("WAD file unpacked!");
+    Ok(())
+}
--- a/src/title/content.rs
+++ b/src/title/content.rs
@ -3,10 +3,11 @@
 //
 // Implements content parsing and editing.

+use std::cell::RefCell;
 use std::io::{Cursor, Read, Seek, SeekFrom, Write};
+use std::rc::Rc;
 use sha1::{Sha1, Digest};
 use thiserror::Error;
-use crate::title::content::ContentError::MissingContents;
 use crate::title::tmd::{ContentRecord, ContentType};
 use crate::title::crypto;
 use crate::title::crypto::encrypt_content;
@ -19,6 +20,10 @@ pub enum ContentError {
    MissingContents { required: usize, found: usize },
    #[error("content with requested Content ID {0} could not be found")]
    CIDNotFound(u32),
+    #[error("the specified index {0} already exists in the content records")]
+    IndexAlreadyExists(u16),
+    #[error("the specified Content ID {0} already exists in the content records")]
+    CIDAlreadyExists(u32),
    #[error("content's hash did not match the expected value (was {hash}, expected {expected})")]
    BadHash { hash: String, expected: String },
    #[error("content data is not in a valid format")]
@ -28,9 +33,8 @@ pub enum ContentError {
 #[derive(Debug)]
 /// A structure that represents the block of data containing the content of a digital Wii title.
 pub struct ContentRegion {
-    pub content_records: Vec<ContentRecord>,
+    pub content_records: Rc<RefCell<Vec<ContentRecord>>>,
    pub content_region_size: u32,
-    pub num_contents: u16,
    pub content_start_offsets: Vec<u64>,
    pub contents: Vec<Vec<u8>>,
 }
@ -38,32 +42,31 @@ pub struct ContentRegion {
 impl ContentRegion {
    /// Creates a ContentRegion instance that can be used to parse and edit content stored in a 
    /// digital Wii title from the content area of a WAD and the ContentRecords from a TMD.
-    pub fn from_bytes(data: &[u8], content_records: Vec<ContentRecord>) -> Result<Self, ContentError> {
+    pub fn from_bytes(data: &[u8], content_records: Rc<RefCell<Vec<ContentRecord>>>) -> Result<Self, ContentError> {
        let content_region_size = data.len() as u32;
-        let num_contents = content_records.len() as u16;
+        let num_contents = content_records.borrow().len() as u16;
        // Calculate the starting offsets of each content.
        let content_start_offsets: Vec<u64> = std::iter::once(0)
-            .chain(content_records.iter().scan(0, |offset, record| {
+            .chain(content_records.borrow().iter().scan(0, |offset, record| {
                *offset += record.content_size;
                if record.content_size % 64 != 0 {
                    *offset += 64 - (record.content_size % 64);
                }
                Some(*offset)
-            })).take(content_records.len()).collect(); // Trims the extra final entry.
+            })).take(content_records.borrow().len()).collect(); // Trims the extra final entry.
        // Parse the content blob and create a vector of vectors from it.
        let mut contents: Vec<Vec<u8>> = Vec::with_capacity(num_contents as usize);
        let mut buf = Cursor::new(data);
        for i in 0..num_contents {
            buf.seek(SeekFrom::Start(content_start_offsets[i as usize]))?;
-            let size = (content_records[i as usize].content_size + 15) & !15;
+            let size = (content_records.borrow()[i as usize].content_size + 15) & !15;
            let mut content = vec![0u8; size as usize];
            buf.read_exact(&mut content)?;
            contents.push(content);
        }
        Ok(ContentRegion {
-            content_records,
+            content_records: Rc::clone(&content_records),
            content_region_size,
-            num_contents,
            content_start_offsets,
            contents,
        })
@ -71,29 +74,29 @@ impl ContentRegion {

    /// Creates a ContentRegion instance that can be used to parse and edit content stored in a 
    /// digital Wii title from a vector of contents and the ContentRecords from a TMD.
-    pub fn from_contents(contents: Vec<Vec<u8>>, content_records: Vec<ContentRecord>) -> Result<Self, ContentError> {
-        if contents.len() != content_records.len() {
-            return Err(MissingContents { required: content_records.len(), found: contents.len()});
+    pub fn from_contents(contents: Vec<Vec<u8>>, content_records: Rc<RefCell<Vec<ContentRecord>>>) -> Result<Self, ContentError> {
+        if contents.len() != content_records.borrow().len() {
+            return Err(ContentError::MissingContents { required: content_records.borrow().len(), found: contents.len()});
        }
-        let mut content_region = Self::new(content_records)?;
+        let mut content_region = Self::new(Rc::clone(&content_records))?;
        for i in 0..contents.len() {
-            content_region.load_enc_content(&contents[i], content_region.content_records[i].index as usize)?;
+            let target_index = content_region.content_records.borrow()[i].index;
+            content_region.load_enc_content(&contents[i], target_index as usize)?;
        }
        Ok(content_region)
    }
    
    /// Creates a ContentRegion instance from the ContentRecords of a TMD that contains no actual
    /// content. This can be used to load existing content from files.
-    pub fn new(content_records: Vec<ContentRecord>) -> Result<Self, ContentError> {
-        let content_region_size: u64 = content_records.iter().map(|x| (x.content_size + 63) & !63).sum();
+    pub fn new(content_records: Rc<RefCell<Vec<ContentRecord>>>) -> Result<Self, ContentError> {
+        let content_region_size: u64 = content_records.borrow().iter().map(|x| (x.content_size + 63) & !63).sum();
        let content_region_size = content_region_size as u32;
-        let num_contents = content_records.len() as u16;
+        let num_contents = content_records.borrow().len() as u16;
        let content_start_offsets: Vec<u64> = vec![0; num_contents as usize];
        let contents: Vec<Vec<u8>> = vec![Vec::new(); num_contents as usize];
        Ok(ContentRegion {
-            content_records,
+            content_records:  Rc::clone(&content_records),
            content_region_size,
-            num_contents,
            content_start_offsets,
            contents,
        })
@ -102,7 +105,7 @@ impl ContentRegion {
    /// Dumps the entire ContentRegion back into binary data that can be written to a file.
    pub fn to_bytes(&self) -> Result<Vec<u8>, std::io::Error> {
        let mut buf: Vec<u8> = Vec::new();
-        for i in 0..self.num_contents {
+        for i in 0..self.content_records.borrow().len() {
            let mut content = self.contents[i as usize].clone();
            // Round up size to nearest 64 to add appropriate padding.
            content.resize((content.len() + 63) & !63, 0);
@ -115,7 +118,7 @@ impl ContentRegion {
    pub fn get_index_from_cid(&self, cid: u32) -> Result<usize, ContentError> {
        // Use fancy Rust find and map methods to find the index matching the provided CID. Take
        // that libWiiPy!
-        let content_index = self.content_records.iter()
+        let content_index = self.content_records.borrow().iter()
            .find(|record| record.content_id == cid)
            .map(|record| record.index);
        if let Some(index) = content_index {
@ -127,7 +130,7 @@ impl ContentRegion {

    /// Gets the encrypted content file from the ContentRegion at the specified index.
    pub fn get_enc_content_by_index(&self, index: usize) -> Result<Vec<u8>, ContentError> {
-        let content = self.contents.get(index).ok_or(ContentError::IndexOutOfRange { index, max: self.content_records.len() - 1 })?;
+        let content = self.contents.get(index).ok_or(ContentError::IndexOutOfRange { index, max: self.content_records.borrow().len() - 1 })?;
        Ok(content.clone())
    }

@ -135,20 +138,20 @@ impl ContentRegion {
    pub fn get_content_by_index(&self, index: usize, title_key: [u8; 16]) -> Result<Vec<u8>, ContentError> {
        let content = self.get_enc_content_by_index(index)?;
        // Verify the hash of the decrypted content against its record.
-        let mut content_dec = crypto::decrypt_content(&content, title_key, self.content_records[index].index);
-        content_dec.resize(self.content_records[index].content_size as usize, 0);
+        let mut content_dec = crypto::decrypt_content(&content, title_key, self.content_records.borrow()[index].index);
+        content_dec.resize(self.content_records.borrow()[index].content_size as usize, 0);
        let mut hasher = Sha1::new();
        hasher.update(content_dec.clone());
        let result = hasher.finalize();
-        if result[..] != self.content_records[index].content_hash {
-            return Err(ContentError::BadHash { hash: hex::encode(result), expected: hex::encode(self.content_records[index].content_hash) });
+        if result[..] != self.content_records.borrow()[index].content_hash {
+            return Err(ContentError::BadHash { hash: hex::encode(result), expected: hex::encode(self.content_records.borrow()[index].content_hash) });
        }
        Ok(content_dec)
    }

    /// Gets the encrypted content file from the ContentRegion with the specified Content ID.
    pub fn get_enc_content_by_cid(&self, cid: u32) -> Result<Vec<u8>, ContentError> {
-        let index = self.content_records.iter().position(|x| x.content_id == cid);
+        let index = self.content_records.borrow().iter().position(|x| x.content_id == cid);
        if let Some(index) = index {
            let content = self.get_enc_content_by_index(index).map_err(|_| ContentError::CIDNotFound(cid))?;
            Ok(content)
@ -159,7 +162,7 @@ impl ContentRegion {

    /// Gets the decrypted content file from the ContentRegion with the specified Content ID.
    pub fn get_content_by_cid(&self, cid: u32, title_key: [u8; 16]) -> Result<Vec<u8>, ContentError> {
-        let index = self.content_records.iter().position(|x| x.content_id == cid);
+        let index = self.content_records.borrow().iter().position(|x| x.content_id == cid);
        if let Some(index) = index {
            let content_dec = self.get_content_by_index(index, title_key)?;
            Ok(content_dec)
@ -171,8 +174,8 @@ impl ContentRegion {
    /// Loads existing content into the specified index of a ContentRegion instance. This content 
    /// must be encrypted.
    pub fn load_enc_content(&mut self, content: &[u8], index: usize) -> Result<(), ContentError> {
-        if index >= self.content_records.len() {
-            return Err(ContentError::IndexOutOfRange { index, max: self.content_records.len() - 1 });
+        if index >= self.content_records.borrow().len() {
+            return Err(ContentError::IndexOutOfRange { index, max: self.content_records.borrow().len() - 1 });
        }
        self.contents[index] = content.to_vec();
        Ok(())
@ -183,16 +186,20 @@ impl ContentRegion {
    /// values can be set in the corresponding content record. Optionally, a new Content ID or
    /// content type can be provided, with the existing values being preserved by default.
    pub fn set_enc_content(&mut self, content: &[u8], index: usize, content_size: u64, content_hash: [u8; 20], cid: Option<u32>, content_type: Option<ContentType>) -> Result<(), ContentError> {
-        if index >= self.content_records.len() {
-            return Err(ContentError::IndexOutOfRange { index, max: self.content_records.len() - 1 });
+        if index >= self.content_records.borrow().len() {
+            return Err(ContentError::IndexOutOfRange { index, max: self.content_records.borrow().len() - 1 });
        }
-        self.content_records[index].content_size = content_size;
-        self.content_records[index].content_hash = content_hash;
+        self.content_records.borrow_mut()[index].content_size = content_size;
+        self.content_records.borrow_mut()[index].content_hash = content_hash;
        if cid.is_some() {
-            self.content_records[index].content_id = cid.unwrap();
+            // Make sure that the new CID isn't already in use.
+            if self.content_records.borrow().iter().any(|record| record.content_id == cid.unwrap()) {
+                return Err(ContentError::CIDAlreadyExists(cid.unwrap()));
+            }
+            self.content_records.borrow_mut()[index].content_id = cid.unwrap();
        }
        if content_type.is_some() {
-            self.content_records[index].content_type = content_type.unwrap();
+            self.content_records.borrow_mut()[index].content_type = content_type.unwrap();
        }
        self.contents[index] = content.to_vec();
        Ok(())
@ -202,18 +209,18 @@ impl ContentRegion {
    /// must be decrypted and needs to match the size and hash listed in the content record at that
    /// index.
    pub fn load_content(&mut self, content: &[u8], index: usize, title_key: [u8; 16]) -> Result<(), ContentError> {
-        if index >= self.content_records.len() {
-            return Err(ContentError::IndexOutOfRange { index, max: self.content_records.len() - 1 });
+        if index >= self.content_records.borrow().len() {
+            return Err(ContentError::IndexOutOfRange { index, max: self.content_records.borrow().len() - 1 });
        }
        // Hash the content we're trying to load to ensure it matches the hash expected in the
        // matching record.
        let mut hasher = Sha1::new();
        hasher.update(content);
        let result = hasher.finalize();
-        if result[..] != self.content_records[index].content_hash {
-            return Err(ContentError::BadHash { hash: hex::encode(result), expected: hex::encode(self.content_records[index].content_hash) });
+        if result[..] != self.content_records.borrow()[index].content_hash {
+            return Err(ContentError::BadHash { hash: hex::encode(result), expected: hex::encode(self.content_records.borrow()[index].content_hash) });
        }
-        let content_enc = encrypt_content(content, title_key, self.content_records[index].index, self.content_records[index].content_size);
+        let content_enc = encrypt_content(content, title_key, self.content_records.borrow()[index].index, self.content_records.borrow()[index].content_size);
        self.contents[index] = content_enc;
        Ok(())
    }
@ -231,4 +238,50 @@ impl ContentRegion {
        self.set_enc_content(&content_enc, index, content_size, content_hash, cid, content_type)?;
        Ok(())
    }
+    
+    /// Removes the content at the specified index from the content list and content records. This
+    /// may leave a gap in the indexes recorded in the content records, but this should not cause
+    /// issues on the Wii or with correctly implemented WAD parsers.
+    pub fn remove_content(&mut self, index: usize) -> Result<(), ContentError> {
+        if self.contents.get(index).is_none() || self.content_records.borrow().get(index).is_none() {
+            return Err(ContentError::IndexOutOfRange { index, max: self.content_records.borrow().len() - 1 });
+        }
+        self.contents.remove(index);
+        self.content_records.borrow_mut().remove(index);
+        Ok(())
+    }
+
+    /// Adds new encrypted content to the end of the content list and content records. The provided
+    /// Content ID, type, index, and decrypted hash will be added to the record.
+    pub fn add_enc_content(&mut self, content: &[u8], index: u16, cid: u32, content_type: ContentType, content_size: u64, content_hash: [u8; 20]) -> Result<(), ContentError> {
+        // Return an error if the specified index or CID already exist in the records.
+        if self.content_records.borrow().iter().any(|record| record.index == index) {
+            return Err(ContentError::IndexAlreadyExists(index));
+        }
+        if self.content_records.borrow().iter().any(|record| record.content_id == cid) {
+            return Err(ContentError::CIDAlreadyExists(cid));
+        }
+        self.contents.push(content.to_vec());
+        self.content_records.borrow_mut().push(ContentRecord { content_id: cid, index, content_type, content_size, content_hash });
+        Ok(())
+    }
+    
+    /// Adds new decrypted content to the end of the content list and content records. The provided
+    /// Content ID and type will be added to the record alongside a hash of the decrypted data. An
+    /// index will be automatically assigned based on the highest index currently recorded in the
+    /// content records.
+    pub fn add_content(&mut self, content: &[u8], cid: u32, content_type: ContentType, title_key: [u8; 16]) -> Result<(), ContentError> {
+        let max_index = self.content_records.borrow().iter()
+            .max_by_key(|record| record.index)
+            .map(|record| record.index)
+            .unwrap_or(0); // This should be impossible, but I guess 0 is a safe value just in case?
+        let new_index = max_index + 1;
+        let content_size = content.len() as u64;
+        let mut hasher = Sha1::new();
+        hasher.update(content);
+        let content_hash: [u8; 20] = hasher.finalize().into();
+        let content_enc = encrypt_content(content, title_key, new_index, content_size);
+        self.add_enc_content(&content_enc, new_index, cid, content_type, content_size, content_hash)?;
+        Ok(())
+    }
 }
--- a/src/title/mod.rs
+++ b/src/title/mod.rs
@ -13,6 +13,7 @@ pub mod tmd;
 pub mod versions;
 pub mod wad;

+use std::rc::Rc;
 use thiserror::Error;

 #[derive(Debug, Error)]
@ -52,7 +53,7 @@ impl Title {
        let cert_chain = cert::CertificateChain::from_bytes(&wad.cert_chain()).map_err(TitleError::CertificateError)?;
        let ticket = ticket::Ticket::from_bytes(&wad.ticket()).map_err(TitleError::Ticket)?;
        let tmd = tmd::TMD::from_bytes(&wad.tmd()).map_err(TitleError::TMD)?;
-        let content = content::ContentRegion::from_bytes(&wad.content(), tmd.content_records.clone()).map_err(TitleError::Content)?;
+        let content = content::ContentRegion::from_bytes(&wad.content(), Rc::clone(&tmd.content_records)).map_err(TitleError::Content)?;
        Ok(Title {
            cert_chain,
            crl: wad.crl(),
@ -137,7 +138,15 @@ impl Title {
    /// content type can be provided, with the existing values being preserved by default.
    pub fn set_content(&mut self, content: &[u8], index: usize, cid: Option<u32>, content_type: Option<tmd::ContentType>) -> Result<(), TitleError> {
        self.content.set_content(content, index, cid, content_type, self.ticket.dec_title_key())?;
-        self.tmd.content_records = self.content.content_records.clone();
+        Ok(())
+    }
+
+    /// Adds new decrypted content to the end of the content list and content records. The provided
+    /// Content ID and type will be added to the record alongside a hash of the decrypted data. An
+    /// index will be automatically assigned based on the highest index currently recorded in the
+    /// content records.
+    pub fn add_content(&mut self, content: &[u8], cid: u32, content_type: tmd::ContentType) -> Result<(), TitleError> {
+        self.content.add_content(content, cid, content_type, self.ticket.dec_title_key())?;
        Ok(())
    }
    
@ -149,7 +158,7 @@ impl Title {
        // accurate results.
        title_size += self.tmd.to_bytes().map_err(|x| TitleError::TMD(tmd::TMDError::IO(x)))?.len();
        title_size += self.ticket.to_bytes().map_err(|x| TitleError::Ticket(ticket::TicketError::IO(x)))?.len();
-        for record in &self.tmd.content_records {
+        for record in self.tmd.content_records.borrow().iter() {
            if matches!(record.content_type, tmd::ContentType::Shared) {
                if absolute == Some(true) {
                    title_size += record.content_size as usize;
--- a/src/title/nus.rs
+++ b/src/title/nus.rs
@ -80,7 +80,7 @@ pub fn download_content(title_id: [u8; 8], content_id: u32, wiiu_endpoint: bool)

 /// Downloads all contents from the specified title from the NUS.
 pub fn download_contents(tmd: &tmd::TMD, wiiu_endpoint: bool) -> Result<Vec<Vec<u8>>, NUSError> {
-    let content_ids: Vec<u32> = tmd.content_records.iter().map(|record| { record.content_id }).collect();
+    let content_ids: Vec<u32> = tmd.content_records.borrow().iter().map(|record| { record.content_id }).collect();
    let mut contents: Vec<Vec<u8>> = Vec::new();
    for id in content_ids {
        contents.push(download_content(tmd.title_id, id, wiiu_endpoint)?);
--- a/src/title/tmd.rs
+++ b/src/title/tmd.rs
@ -3,9 +3,11 @@
 //
 // Implements the structures and methods required for TMD parsing and editing.

+use std::cell::RefCell;
 use std::fmt;
 use std::io::{Cursor, Read, Write};
 use std::ops::Index;
+use std::rc::Rc;
 use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
 use sha1::{Sha1, Digest};
 use thiserror::Error;
@ -110,7 +112,7 @@ pub struct TMD {
    pub num_contents: u16,
    pub boot_index: u16,
    pub minor_version: u16, // Normally unused, but good for fakesigning!
-    pub content_records: Vec<ContentRecord>,
+    pub content_records: Rc<RefCell<Vec<ContentRecord>>>,
 }

 impl TMD {
@ -204,7 +206,7 @@ impl TMD {
            num_contents,
            boot_index,
            minor_version,
-            content_records,
+            content_records: Rc::new(RefCell::new(content_records)),
        })
    }
    
@ -231,11 +233,11 @@ impl TMD {
        buf.write_all(&self.reserved2)?;
        buf.write_u32::<BigEndian>(self.access_rights)?;
        buf.write_u16::<BigEndian>(self.title_version)?;
-        buf.write_u16::<BigEndian>(self.num_contents)?;
+        buf.write_u16::<BigEndian>(self.content_records.borrow().len() as u16)?;
        buf.write_u16::<BigEndian>(self.boot_index)?;
        buf.write_u16::<BigEndian>(self.minor_version)?;
        // Iterate over content records and write out content record data.
-        for content in &self.content_records {
+        for content in self.content_records.borrow().iter() {
            buf.write_u32::<BigEndian>(content.content_id)?;
            buf.write_u16::<BigEndian>(content.index)?;
            match content.content_type {
@ -317,11 +319,11 @@ impl TMD {
        // Find possible content indices, because the provided one could exist while the indices
        // are out of order, which could cause problems finding the content.
        let mut content_indices = Vec::new();
-        for record in &self.content_records {
+        for record in self.content_records.borrow().iter() {
            content_indices.push(record.index);
        }
        let target_index = content_indices.index(index);
-        match self.content_records[*target_index as usize].content_type {
+        match self.content_records.borrow()[*target_index as usize].content_type {
            ContentType::Normal => ContentType::Normal,
            ContentType::Development => ContentType::Development,
            ContentType::HashTree => ContentType::HashTree,