Basic functionality (and initial repro crate)

Adds extremely basic functionality for invoking `cargo build --locked`
as `cargo repro build`.

Though this may seem fairly pointless in and of itself, the goal of a
followup commit would be to collect environmental information during
this step (OS/release, rustc/cargo version, CWD, environment variables,
git commit, C/C++ compiler versions if applicable) and use that during
the verification process to detect and highlight mismatches.

This commit attempts to split the CLI app (i.e. `cargo-repro`) from a
library-level crate containing the core functionality (ala `cargo-audit`
and the `rustsec` crate), in case there is interest in driving these
sorts of builds from external tooling.

.travis.yml

@@ -15,17 +15,17 @@ matrix:
   include:
     - name: rustfmt
       script:
-        - cargo fmt -- --check
+        - cargo fmt --all -- --check
     - name: clippy
       script:
-        - cargo clippy
+        - cargo clippy --all
     - name: build
       script:
-        - cargo build --release
+        - cargo build --all --release
     - name: test
       script:
-        - cargo test --release
+        - cargo test --all --release
     - name: test (1.31.0)
       rust: 1.31.0
       script:
-        - cargo test --release
+        - cargo test --all --release

Cargo.toml

@@ -17,3 +17,7 @@ keywords    = ["cargo", "deterministic", "reproducible", "security", "verifiable
 maintenance = { status = "experimental" }
 
 [dependencies]
+repro = { version = "0", path = "repro" }
+
+[workspace]
+members = [".", "repro"]

repro/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name        = "repro"
+description = """
+              Support crate for cargo-repro, a tool for building and verifying
+              Rust packages that are reproducible byte-for-byte using a
+              Cargo-driven workflow.
+              """
+version     = "0.0.0"
+authors     = ["Rust Secure Code WG <[email protected]>"]
+edition     = "2018"
+license     = "Apache-2.0 OR MIT"
+readme      = "README.md"
+repository  = "https://github.com/rust-secure-code/cargo-repro"
+categories  = ["command-line-utilities", "development-tools", "rust-patterns"]
+keywords    = ["cargo", "deterministic", "reproducible", "security", "verifiable"]
+
+[badges]
+maintenance = { status = "experimental" }
+
+[dependencies]

repro/src/builder.rs

@@ -0,0 +1,78 @@
+//! Rust project builder - wrapper for invoking Cargo
+
+use std::{
+    ffi::OsString,
+    process::{Child, Command, ExitStatus},
+};
+
+/// Name of the `cargo` executable
+const CARGO_EXE: &str = "cargo";
+
+/// Rust project builder
+#[derive(Clone, Debug)]
+pub struct Builder {
+    program: OsString,
+    args: Vec<OsString>,
+}
+
+impl Default for Builder {
+    fn default() -> Self {
+        Self::new(CARGO_EXE)
+    }
+}
+
+impl Builder {
+    /// Create `Builder` that invokes the given command with the given arguments
+    pub fn new<S>(program: S) -> Self
+    where
+        S: Into<OsString>,
+    {
+        Self {
+            program: program.into(),
+            args: vec![],
+        }
+    }
+
+    /// Append an argument to the set of arguments to run
+    pub fn arg<S>(&mut self, arg: S) -> &mut Self
+    where
+        S: Into<OsString>,
+    {
+        self.args.push(arg.into());
+        self
+    }
+
+    /// Append multiple arguments to the set of arguments to run
+    pub fn args<I, S>(&mut self, args: I) -> &mut Self
+    where
+        I: IntoIterator<Item = S>,
+        S: Into<OsString>,
+    {
+        self.args.extend(args.into_iter().map(|a| a.into()));
+        self
+    }
+
+    /// Run the given subcommand
+    pub fn run(&self) -> Process {
+        let child = Command::new(&self.program)
+            .args(&self.args)
+            .spawn()
+            .unwrap_or_else(|e| {
+                panic!("error running command: {}", e);
+            });
+
+        Process(child)
+    }
+}
+
+/// Wrapper for the builder subprocess
+pub struct Process(Child);
+
+impl Process {
+    /// Wait for the child to finish
+    pub fn wait(mut self) -> ExitStatus {
+        self.0
+            .wait()
+            .unwrap_or_else(|e| panic!("couldn't get child's exit status: {}", e))
+    }
+}

repro/src/lib.rs

@@ -0,0 +1,10 @@
+//! `repro` crate: perform and verify reproducible builds of Rust code
+
+#![forbid(unsafe_code)]
+#![deny(warnings, missing_docs, trivial_casts, unused_qualifications)]
+#![doc(
+    html_logo_url = "https://avatars3.githubusercontent.com/u/44121472",
+    html_root_url = "https://docs.rs/repro/0.0.0"
+)]
+
+pub mod builder;

src/commands.rs

@@ -0,0 +1,44 @@
+//! `cargo repro` subcommands
+
+pub mod build;
+pub mod verify;
+
+use self::{build::BuildCommand, verify::VerifyCommand};
+
+/// `cargo repro` subcommands
+pub enum Command {
+    /// `cargo repro build` subcommand
+    Build(BuildCommand),
+
+    /// `cargo repro verify` subcommand
+    Verify(VerifyCommand),
+}
+
+impl Command {
+    /// Parse command to execute from CLI args
+    pub fn from_args(mut args: impl Iterator<Item = String>) -> Option<Self> {
+        // ARGV[0] is always the name of the executed binary
+        args.next().unwrap();
+
+        // Cargo passes `repro` as the first argument when invoking `cargo repro`
+        if args.next().as_ref().map(String::as_str) != Some("repro") {
+            return None;
+        }
+
+        let command = match args.next().as_ref().map(String::as_str) {
+            Some("build") => Command::Build(BuildCommand::from_args(args)),
+            Some("verify") => Command::Verify(VerifyCommand::from_args(args)),
+            _ => return None,
+        };
+
+        Some(command)
+    }
+
+    /// Run the parsed command
+    pub fn run(&self) {
+        match self {
+            Command::Build(build) => build.run(),
+            Command::Verify(verify) => verify.run(),
+        }
+    }
+}

src/commands/build.rs

@@ -0,0 +1,48 @@
+//! `cargo repro build` subcommand
+
+use repro::builder::Builder;
+
+/// Cargo argument for a locked build. This is needed to ensure the build
+/// is reproducible.
+pub const LOCKED_ARG: &str = "--locked";
+
+/// `cargo repro build` subcommand
+pub struct BuildCommand {
+    /// Arguments passed to `cargo repro build` (to be passed to Cargo)
+    pub args: Vec<String>,
+}
+
+impl BuildCommand {
+    /// Initialize this command from the given arguments, which should *NOT*
+    /// include `["cargo", "repro", "build"]`
+    pub fn from_args(args: impl Iterator<Item = String>) -> Self {
+        Self {
+            args: args.collect(),
+        }
+    }
+
+    /// Run this subcommand
+    // TODO(tarcieri): factor more of this logic into the `repro` crate?
+    pub fn run(&self) {
+        let mut builder = Builder::default();
+        builder.arg("build");
+
+        // Add the `--locked` argument unless it's been specified explicitly
+        if !self.args.iter().any(|arg| arg.as_str() == LOCKED_ARG) {
+            builder.arg(LOCKED_ARG);
+        }
+
+        builder.args(&self.args);
+        let exit_status = builder.run().wait();
+
+        if !exit_status.success() {
+            panic!(
+                "cargo exited with non-zero status: {}",
+                exit_status
+                    .code()
+                    .map(|code| code.to_string())
+                    .unwrap_or_else(|| "unknown".to_owned())
+            );
+        }
+    }
+}

src/commands/verify.rs

@@ -0,0 +1,28 @@
+//! `cargo repro verify` subcommand
+
+/// `cargo repro verify` subcommand
+pub struct VerifyCommand {
+    /// Arguments passed to `cargo repro verify` (to be passed to Cargo)
+    pub args: Vec<String>,
+}
+
+impl VerifyCommand {
+    /// Initialize this command from the given arguments, which should *NOT*
+    /// include `["cargo", "repro", "verify"]`
+    pub fn from_args(args: impl Iterator<Item = String>) -> Self {
+        Self {
+            args: args.collect(),
+        }
+    }
+
+    /// Run this subcommand
+    pub fn run(&self) {
+        println!("cargo repro: build and verify byte-for-byte reproducible Rust packages");
+        println!();
+        println!("WORK IN PROGRESS: The 'verify' functionality of this tool is unimplemented.");
+        println!("If you are interested in contributing, please see the GitHub issues:");
+        println!();
+        println!("    https://github.com/rust-secure-code/cargo-repro/issues");
+        println!();
+    }
+}

src/main.rs

@@ -0,0 +1,31 @@
+//! cargo-repro: perform and verify reproducible builds of Rust code with Cargo
+
+#![deny(warnings, missing_docs, trivial_casts, unused_qualifications)]
+#![forbid(unsafe_code)]
+
+pub mod commands;
+
+use commands::Command;
+use std::{env, process};
+
+fn main() {
+    let command = Command::from_args(env::args()).unwrap_or_else(|| usage());
+    command.run();
+}
+
+fn usage() -> ! {
+    println!("{} {}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION"));
+    println!(
+        "{}\n",
+        env!("CARGO_PKG_DESCRIPTION")
+            .split_whitespace()
+            .collect::<Vec<_>>()
+            .join(" ")
+    );
+
+    println!("SUBCOMMANDS:");
+    println!("    build\tPerform a reproducible build of a Cargo project");
+    println!("    verify\t(UNIMPLEMENTED) Verify a reproducible build");
+
+    process::exit(1);
+}