feat(users/Profpatsch): add die_* helpers for semantic exit errors r/2176

There is this semantic exit code schema championed by execline and
skaware tooling, and we refined and documented it a bit in lorri
https://github.com/nix-community/lorri/blob/d1d673d42090f0cfe8ab9b92b465315a9e7d30a3/src/ops/mod.rs#L24-L35
in the past.

This just transcribes the error messages into simple helper functions.

Applies the functions to the places where we would panic or die
`sys::exit()` instead.

Change-Id: I15ca05cd6f99a25a3378518be94110eab416354e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2475
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>

2 files changed, 0 insertions, 214 deletions

diff --git a/users/Profpatsch/read-http/default.nix b/users/Profpatsch/read-http/default.nix
deleted file mode 100644
index 41fe1c7fedcc..000000000000
--- a/users/Profpatsch/read-http/default.nix
+++ /dev/null
@@ -1,20 +0,0 @@
-{ depot, pkgs, ... }:
-
-let
-
-  # reads a http request (stdin), and writes all headers to stdout, as netencoded dict
-  read-http = depot.users.Profpatsch.writers.rustSimple {
-    name = "read-http";
-    dependencies = [
-      depot.users.Profpatsch.rust-crates.ascii
-      depot.users.Profpatsch.rust-crates.httparse
-      depot.users.Profpatsch.netencode.netencode-rs
-      depot.users.Profpatsch.arglib.netencode.rust
-    ];
-  } (builtins.readFile ./read-http.rs);
-
-in {
-  inherit
-    read-http
-    ;
-}
diff --git a/users/Profpatsch/read-http/read-http.rs b/users/Profpatsch/read-http/read-http.rs
deleted file mode 100644
index ab2c3887d7b5..000000000000
--- a/users/Profpatsch/read-http/read-http.rs
+++ /dev/null
@@ -1,194 +0,0 @@
-extern crate httparse;
-extern crate netencode;
-extern crate arglib_netencode;
-extern crate ascii;
-
-use std::os::unix::io::FromRawFd;
-use std::io::Read;
-use std::io::Write;
-
-use netencode::{U, T};
-
-enum What {
-    Request,
-    Response
-}
-
-fn main() -> std::io::Result<()> {
-    fn die<T: std::fmt::Display>(msg: T) -> ! {
-        eprintln!("{}", msg);
-        std::process::exit(1);
-    }
-
-    let what : What = match arglib_netencode::arglib_netencode(None).unwrap() {
-        T::Record(rec) => match rec.get("what") {
-            Some(T::Text(t)) => match t.as_str() {
-                "request" => What::Request,
-                "response" => What::Response,
-                _ => die("read-http arglib: what should be either t:request or t:response"),
-            },
-            Some(o) => die(format!("read-http arglib: expected a record of text, got {:#?}", o)),
-            None => {
-                eprintln!("read-http arglib: no `what` given, defaulting to Response");
-                What::Response
-            }
-        }
-        o => die(format!("read-http arglib: expected a record, got {:#?}", o))
-    };
-
-    fn read_stdin_to_complete<F>(mut parse: F) -> ()
-        where F: FnMut(&[u8]) -> httparse::Result<usize>
-    {
-        let mut res = httparse::Status::Partial;
-        loop {
-            if let httparse::Status::Complete(_) = res {
-                return;
-            }
-            let mut buf = [0; 2048];
-            match std::io::stdin().read(&mut buf[..]) {
-                Ok(size) => if size == 0 {
-                    break;
-                },
-                Err(err) => panic!("could not read from stdin, {:?}", err)
-            }
-            match parse(&buf) {
-                Ok(status) => {
-                    res = status;
-                }
-                Err(err) => die(format!("httparse parsing failed: {:#?}", err))
-            }
-        }
-    }
-
-
-    fn normalize_headers<'a>(headers: &'a [httparse::Header]) -> Vec<(String, &'a str)> {
-        let mut res = vec![];
-        for httparse::Header { name, value } in headers {
-            let val = ascii::AsciiStr::from_ascii(*value)
-                .expect(&format!("read-http: we require header values to be ASCII, but the header {} was {:?}", name, value));
-            // lowercase the headers, since the standard doesn’t care
-            // and we want unique strings to match agains
-            res.push((name.to_lowercase(), val.as_str()))
-        }
-        res
-    }
-
-    // tries to read until the end of the http header (deliniated by two newlines "\r\n\r\n")
-    fn read_till_end_of_header<R: Read>(buf: &mut Vec<u8>, reader: R) -> Option<()> {
-        let mut chunker = Chunkyboi::new(reader, 4096);
-        loop {
-            match chunker.next() {
-                Some(Ok(chunk)) => {
-                    buf.extend_from_slice(&chunk);
-                    if chunk.windows(4).any(|c| c == b"\r\n\r\n" ) {
-                        return Some(());
-                    }
-                },
-                Some(Err(err)) => die(format!("error reading from stdin: {:?}", err)),
-                None => return None
-            }
-        }
-    }
-
-    // max header size chosen arbitrarily
-    let mut headers = [httparse::EMPTY_HEADER; 128];
-    let stdin = std::io::stdin();
-
-    match what {
-        Request => {
-            let mut req = httparse::Request::new(&mut headers);
-            let mut buf: Vec<u8> = vec![];
-            match read_till_end_of_header(&mut buf, stdin.lock()) {
-                Some(()) => match req.parse(&buf) {
-                    Ok(httparse::Status::Complete(_body_start)) => {},
-                    Ok(httparse::Status::Partial) => die("httparse should have gotten a full header"),
-                    Err(err) => die(format!("httparse response parsing failed: {:#?}", err))
-                },
-                None => die(format!("httparse end of stdin reached before able to parse request headers"))
-            }
-            let method = req.method.expect("method must be filled on complete parse");
-            let path = req.path.expect("path must be filled on complete parse");
-            write_dict_req(method, path, &normalize_headers(req.headers))
-        },
-        Response => {
-            let mut resp = httparse::Response::new(&mut headers);
-            let mut buf: Vec<u8> = vec![];
-            match read_till_end_of_header(&mut buf, stdin.lock()) {
-                Some(()) => match resp.parse(&buf) {
-                    Ok(httparse::Status::Complete(_body_start)) => {},
-                    Ok(httparse::Status::Partial) => die("httparse should have gotten a full header"),
-                    Err(err) => die(format!("httparse response parsing failed: {:#?}", err))
-                },
-                None => die(format!("httparse end of stdin reached before able to parse response headers"))
-            }
-            let code = resp.code.expect("code must be filled on complete parse");
-            let reason = resp.reason.expect("reason must be filled on complete parse");
-            write_dict_resp(code, reason, &normalize_headers(resp.headers))
-        }
-    }
-}
-
-fn write_dict_req<'buf>(method: &'buf str, path: &'buf str, headers: &[(String, &str)]) -> std::io::Result<()> {
-    let mut http = vec![
-        ("method", U::Text(method.as_bytes())),
-        ("path", U::Text(path.as_bytes())),
-    ];
-    write_dict(http, headers)
-}
-
-fn write_dict_resp<'buf>(code: u16, reason: &'buf str, headers: &[(String, &str)]) -> std::io::Result<()> {
-    let mut http = vec![
-        ("status", U::N6(code as u64)),
-        ("status-text", U::Text(reason.as_bytes())),
-    ];
-    write_dict(http, headers)
-}
-
-
-fn write_dict<'buf, 'a>(mut http: Vec<(&str, U<'a>)>, headers: &'a[(String, &str)]) -> std::io::Result<()> {
-    http.push(("headers", U::Record(
-        headers.iter().map(
-            |(name, value)|
-            (name.as_str(), U::Text(value.as_bytes()))
-        ).collect::<Vec<_>>()
-    )));
-
-    netencode::encode(
-        &mut std::io::stdout(),
-        U::Record(http)
-    )?;
-    Ok(())
-}
-
-
-// iter helper
-
-struct Chunkyboi<T> {
-    inner: T,
-    buf: Vec<u8>,
-}
-
-impl<R: Read> Chunkyboi<R> {
-    fn new(inner: R, chunksize: usize) -> Self {
-        let buf = vec![0; chunksize];
-        Chunkyboi {
-            inner,
-            buf
-        }
-    }
-}
-
-impl<R: Read> Iterator for Chunkyboi<R> {
-    type Item = std::io::Result<Vec<u8>>;
-
-    fn next(&mut self) -> Option<std::io::Result<Vec<u8>>> {
-        match self.inner.read(&mut self.buf) {
-            Ok(0) => None,
-            Ok(read) => {
-                // clone a new buffer so we can reuse the internal one
-                Some(Ok(self.buf[..read].to_owned()))
-            }
-            Err(err) => Some(Err(err))
-        }
-    }
-}