feat(tvix): set up a simple command line parser for nix-store r/3522

We are going to have a 1:1 drop-in replacement for the old-style nix
tools, and this starts implementing the cli parser part.

The first step is to have a simple integration test suite that can
verify that we match the nix CLI.

clap is a super complicated parsing library, but looking through the
rest they are either too opinioated to be of use for us, or depend on
clap as implementation.

Change-Id: I4cf6051f3a4f782c3242fd0d2b9eab3fbe33d8ad
Reviewed-on: https://cl.tvl.fyi/c/depot/+/4756
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
Autosubmit: Profpatsch <mail@profpatsch.de>

3 files changed, 347 insertions, 2 deletions

diff --git a/tvix/Cargo.lock b/tvix/Cargo.lock
index 75581ea7d9..15d97837e6 100644
--- a/tvix/Cargo.lock
+++ b/tvix/Cargo.lock
@@ -3,5 +3,246 @@
 version = 3
 
 [[package]]
+name = "atty"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d9b39be18770d11421cdb1b9947a45dd3f37e93092cbf377614828a319d5fee8"
+dependencies = [
+ "hermit-abi",
+ "libc",
+ "winapi",
+]
+
+[[package]]
+name = "autocfg"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
+
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "clap"
+version = "3.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f6f34b09b9ee8c7c7b400fe2f8df39cafc9538b03d6ba7f4ae13e4cb90bfbb7d"
+dependencies = [
+ "atty",
+ "bitflags",
+ "indexmap",
+ "os_str_bytes",
+ "strsim",
+ "termcolor",
+ "textwrap",
+]
+
+[[package]]
+name = "getrandom"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7fcd999463524c52659517fe2cea98493cfe485d10565e7b0fb07dbba7ad2753"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
+[[package]]
+name = "hashbrown"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ab5ef0d4909ef3724cc8cce6ccc8572c5c817592e9285f5464f8e86f8bd3726e"
+
+[[package]]
+name = "hermit-abi"
+version = "0.1.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "62b467343b94ba476dcb2500d242dadbb39557df889310ac77c5d99100aaac33"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "indexmap"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bc633605454125dec4b66843673f01c7df2b89479b32e0ed634e43a91cff62a5"
+dependencies = [
+ "autocfg",
+ "hashbrown",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.112"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b03d17f364a3a042d5e5d46b053bbbf82c92c9430c592dd4c064dc6ee997125"
+
+[[package]]
+name = "memchr"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "308cc39be01b73d0d18f82a0e7b2a3df85245f84af96fdddc5d202d27e47b86a"
+
+[[package]]
+name = "os_str_bytes"
+version = "6.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e22443d1643a904602595ba1cd8f7d896afe56d26712531c5ff73a15b2fbf64"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb9f9e6e233e5c4a35559a617bf40a4ec447db2e84c20b55a6f83167b7e57872"
+
+[[package]]
+name = "rand"
+version = "0.8.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2e7573632e6454cf6b99d7aac4ccca54be06da05aca2ef7423d22d27d4d4bcd8"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+ "rand_hc",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d34f1408f55294453790c48b2f1ebbb1c5b4b7563eb1f418bcfcfdbb06ebb4e7"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "rand_hc"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d51e9f596de227fda2ea6c84607f5558e196eeaf43c986b724ba4fb8fdf497e7"
+dependencies = [
+ "rand_core",
+]
+
+[[package]]
+name = "redox_syscall"
+version = "0.2.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8383f39639269cde97d255a32bdb68c047337295414940c68bdd30c2e13203ff"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
+name = "remove_dir_all"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3acd125665422973a33ac9d3dd2df85edad0f4ae9b00dafb1a05e43a9f5ef8e7"
+dependencies = [
+ "winapi",
+]
+
+[[package]]
+name = "strsim"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
+
+[[package]]
+name = "tempfile"
+version = "3.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dac1c663cfc93810f88aed9b8941d48cabf856a1b111c29a40439018d870eb22"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "rand",
+ "redox_syscall",
+ "remove_dir_all",
+ "winapi",
+]
+
+[[package]]
+name = "termcolor"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2dfed899f0eb03f32ee8c6a0aabdb8a7949659e3466561fc0adf54e26d88c5f4"
+dependencies = [
+ "winapi-util",
+]
+
+[[package]]
+name = "textwrap"
+version = "0.14.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0066c8d12af8b5acd21e00547c3797fde4e8677254a7ee429176ccebbe93dd80"
+
+[[package]]
 name = "tvix"
 version = "0.1.0"
+dependencies = [
+ "clap",
+ "tempfile",
+]
+
+[[package]]
+name = "wasi"
+version = "0.10.2+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
+
+[[package]]
+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-util"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70ec6ce85bb158151cae5e5c87f95a8e97d2c0c4b001223f33a334e3ce5de178"
+dependencies = [
+ "winapi",
+]
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
diff --git a/tvix/Cargo.toml b/tvix/Cargo.toml
index 2a59a77eaf..8b0fbd846a 100644
--- a/tvix/Cargo.toml
+++ b/tvix/Cargo.toml
@@ -5,6 +5,10 @@ edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
+[dependencies.clap]
+version = "3.0.5"
+[dependencies.tempfile]
+version = "3.2.0"
 
 [[bin]]
 name = "nix-store"
diff --git a/tvix/src/bin/nix-store.rs b/tvix/src/bin/nix-store.rs
index 7bf5442cb9..72e3bb2204 100644
--- a/tvix/src/bin/nix-store.rs
+++ b/tvix/src/bin/nix-store.rs
@@ -1,3 +1,103 @@
-fn main () {
-  println!("hello, nix");
+fn main() {
+    main_args(std::env::args().collect()).unwrap_or_else(|e| e.exit());
+}
+
+pub fn main_args(args: Vec<String>) -> clap::Result<NixResult> {
+    let matches = clap::App::new("nix-store")
+        .subcommand(clap::App::new("--add").arg(clap::Arg::new("FILE").required(true).index(1)))
+        .try_get_matches_from(args.iter())?;
+    if let Some(add) = matches.subcommand_matches("--add") {
+        let file = add.value_of("FILE").expect("--add needs a file");
+        let file_contents =
+            std::fs::read_to_string(file).expect(&format!("file {} does not exist", file));
+        Ok(NixResult::FileAddedToStore {
+            content: file_contents,
+        })
+    } else {
+        panic!("read some arguments that we do not know: {:?}", args)
+    }
+}
+
+#[derive(Debug, Eq, PartialEq)]
+pub enum NixResult {
+    FileAddedToStore { content: String },
+}
+
+#[cfg(test)]
+mod integration_tests {
+    use std::{collections::VecDeque, io::Write};
+
+    use super::*;
+
+    #[derive(Debug)]
+    enum NixOutput {
+        Err {
+            status: i32,
+            stdout: String,
+            stderr: String,
+        },
+        Ok {
+            stdout: String,
+            stderr: String,
+        },
+    }
+
+    fn run_nix_command(cmd: &str, args: Vec<String>) -> NixOutput {
+        let out = std::process::Command::new(cmd)
+            .args(args)
+            .output()
+            .expect(&format!("could not run {}", cmd));
+        match out.status.code().expect("no status code!") {
+            0 => NixOutput::Ok {
+                stdout: String::from_utf8_lossy(&out.stdout).trim_end().to_string(),
+                stderr: String::from_utf8_lossy(&out.stderr).trim_end().to_string(),
+            },
+            status => NixOutput::Err {
+                status,
+                stdout: String::from_utf8_lossy(&out.stdout).trim_end().to_string(),
+                stderr: String::from_utf8_lossy(&out.stderr).trim_end().to_string(),
+            },
+        }
+    }
+
+    fn nix_nix_store<'a>(args: Vec<String>) -> NixResult {
+        match run_nix_command("nix-store", args) {
+            err @ NixOutput::Err { .. } => panic!("nix-store --add failed: {:#?}", err),
+            NixOutput::Ok { stdout, .. } => NixResult::FileAddedToStore {
+                content: std::fs::read_to_string(&stdout)
+                    .expect(&format!("cannot open {} as store file", stdout)),
+            },
+        }
+    }
+
+    fn tvix_nix_store<'a>(args: Vec<String>) -> NixResult {
+        eprintln!("running tvix with arguments {:?}", args);
+        let mut args = VecDeque::from(args);
+        args.push_front("tvix-store".to_string());
+        super::main_args(Vec::from(args))
+            .unwrap_or_else(|e| panic!("clap command line parsing failed:\n{}", e))
+    }
+
+    #[test]
+    fn test_nix_store_add() {
+        let file_content = "I am a copied file";
+        let mut tempfile = tempfile::NamedTempFile::new().expect("cannot create temp file");
+        tempfile
+            .write_all(file_content.as_bytes())
+            .expect("could not write to tempfile");
+        assert_eq!(
+            tvix_nix_store(vec![
+                "--add".to_string(),
+                tempfile.path().as_os_str().to_string_lossy().into_owned()
+            ]),
+            nix_nix_store(vec![
+                "--add".to_string(),
+                tempfile.path().as_os_str().to_string_lossy().into_owned()
+            ]),
+            "added file contents were not the same"
+        );
+
+        // make sure the tempfile lives till here
+        drop(tempfile)
+    }
 }