Merge pull request #422 from compoundingtech/schickling-assistant/2026-09-02-github-resource-contract-alignment

feat(resources): align built-in provider components

Author: schickling-assistant

components/github-issue/src/lib.rs

@@ -0,0 +1,292 @@
+use std::io::{self, Read as _};
+use std::os::fd::AsRawFd as _;
+use std::os::unix::process::CommandExt as _;
+use std::path::Path;
+use std::process::{Child, ChildStdout, Command, ExitStatus, Stdio};
+use std::time::{Duration, Instant};
+
+use reqwest::header::HeaderValue;
+
+const MAX_TOKEN_BYTES: usize = 4096;
+
+pub(crate) fn discover_authorization(executable: &Path, deadline: Instant) -> Option<HeaderValue> {
+    if Instant::now() >= deadline {
+        return None;
+    }
+    let mut command = Command::new(executable);
+    command
+        .args(["auth", "token", "--hostname", "github.com"])
+        .env("GH_PROMPT_DISABLED", "1")
+        .env("GIT_TERMINAL_PROMPT", "0")
+        .stdin(Stdio::null())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::null())
+        .process_group(0);
+    let child = command.spawn().ok()?;
+    let mut child = OwnedChild::new(child).ok()?;
+    let mut stdout = child.child.stdout.take()?;
+    let (status, token) = collect_token(&mut child, &mut stdout, deadline)?;
+    if !status.success() {
+        return None;
+    }
+    authorization_header(token)
+}
+
+fn collect_token(
+    child: &mut OwnedChild,
+    stdout: &mut ChildStdout,
+    deadline: Instant,
+) -> Option<(ExitStatus, SecretBytes)> {
+    let mut token = SecretBytes(Vec::with_capacity(128));
+    let mut status = None;
+    let mut stdout_closed = false;
+    let mut buffer = SecretBuffer([0_u8; 1024]);
+
+    loop {
+        if Instant::now() >= deadline {
+            child.terminate_and_reap();
+            return None;
+        }
+        if status.is_none() {
+            status = child.try_wait().ok()?;
+            if status.is_some() {
+                // The direct child is reaped by try_wait. Terminate any descendants that retained
+                // stdout so the dedicated process group cannot outlive credential discovery.
+                child.terminate_group();
+            }
+        }
+        if stdout_closed {
+            if let Some(status) = status {
+                return Some((status, token));
+            }
+            std::thread::sleep(
+                deadline
+                    .saturating_duration_since(Instant::now())
+                    .min(Duration::from_millis(1)),
+            );
+            continue;
+        }
+
+        let remaining = deadline.saturating_duration_since(Instant::now());
+        let timeout_ms = i32::try_from(remaining.as_millis()).unwrap_or(i32::MAX);
+        let mut descriptor = libc::pollfd {
+            fd: stdout.as_raw_fd(),
+            events: libc::POLLIN | libc::POLLHUP | libc::POLLERR,
+            revents: 0,
+        };
+        // SAFETY: descriptor points to one valid pollfd for the duration of this call.
+        let polled = unsafe { libc::poll(&mut descriptor, 1, timeout_ms) };
+        if polled < 0 {
+            if io::Error::last_os_error().kind() == io::ErrorKind::Interrupted {
+                continue;
+            }
+            return None;
+        }
+        if polled == 0 {
+            continue;
+        }
+        if descriptor.revents & libc::POLLNVAL != 0 {
+            return None;
+        }
+        if descriptor.revents & (libc::POLLIN | libc::POLLHUP | libc::POLLERR) == 0 {
+            continue;
+        }
+
+        let read = if token.0.len() == MAX_TOKEN_BYTES {
+            let mut overflow = SecretBuffer([0_u8; 1]);
+            match stdout.read(&mut overflow.0) {
+                Ok(0) => {
+                    stdout_closed = true;
+                    continue;
+                }
+                Ok(_) => {
+                    child.terminate_and_reap();
+                    return None;
+                }
+                Err(error) if error.kind() == io::ErrorKind::Interrupted => continue,
+                Err(_) => return None,
+            }
+        } else {
+            let available = (MAX_TOKEN_BYTES - token.0.len()).min(buffer.0.len());
+            match stdout.read(&mut buffer.0[..available]) {
+                Ok(0) => {
+                    stdout_closed = true;
+                    continue;
+                }
+                Ok(read) => read,
+                Err(error) if error.kind() == io::ErrorKind::Interrupted => continue,
+                Err(_) => return None,
+            }
+        };
+        token.0.extend_from_slice(&buffer.0[..read]);
+    }
+}
+
+fn authorization_header(token: SecretBytes) -> Option<HeaderValue> {
+    let token_text = std::str::from_utf8(&token.0).ok()?;
+    let token_text = token_text.trim();
+    if token_text.is_empty() {
+        return None;
+    }
+    let mut header = SecretBytes(Vec::with_capacity("Bearer ".len() + token_text.len()));
+    header.0.extend_from_slice(b"Bearer ");
+    header.0.extend_from_slice(token_text.as_bytes());
+    let mut value = HeaderValue::from_bytes(&header.0).ok()?;
+    value.set_sensitive(true);
+    Some(value)
+}
+
+struct SecretBytes(Vec<u8>);
+
+impl Drop for SecretBytes {
+    fn drop(&mut self) {
+        self.0.fill(0);
+    }
+}
+
+struct SecretBuffer<const N: usize>([u8; N]);
+
+impl<const N: usize> Drop for SecretBuffer<N> {
+    fn drop(&mut self) {
+        self.0.fill(0);
+    }
+}
+
+struct OwnedChild {
+    child: Child,
+    process_group: i32,
+    reaped: bool,
+}
+
+impl OwnedChild {
+    fn new(mut child: Child) -> io::Result<Self> {
+        let process_group = match i32::try_from(child.id()) {
+            Ok(process_group) => process_group,
+            Err(_) => {
+                let _ = child.kill();
+                let _ = child.wait();
+                return Err(io::Error::other("child pid did not fit in pid_t"));
+            }
+        };
+        Ok(Self {
+            child,
+            process_group,
+            reaped: false,
+        })
+    }
+
+    fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
+        let status = self.child.try_wait()?;
+        if status.is_some() {
+            self.reaped = true;
+        }
+        Ok(status)
+    }
+
+    fn terminate_group(&self) {
+        // SAFETY: a negative pid addresses the dedicated process group created by process_group.
+        let _ = unsafe { libc::kill(-self.process_group, libc::SIGKILL) };
+    }
+
+    fn terminate_and_reap(&mut self) {
+        self.terminate_group();
+        while !self.reaped {
+            match self.child.wait() {
+                Ok(_) => self.reaped = true,
+                Err(error) if error.kind() == io::ErrorKind::Interrupted => {}
+                Err(_) => break,
+            }
+        }
+    }
+}
+
+impl Drop for OwnedChild {
+    fn drop(&mut self) {
+        self.terminate_and_reap();
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::fs;
+    use std::os::unix::fs::PermissionsExt as _;
+    use std::path::PathBuf;
+
+    use tempfile::TempDir;
+
+    use super::*;
+
+    #[test]
+    fn discovers_a_sensitive_authorization_header() {
+        let (_temporary, executable) = executable_fixture("printf '%s\\n' 'fixture-token'");
+        let authorization =
+            discover_authorization(&executable, Instant::now() + Duration::from_secs(5)).unwrap();
+
+        assert!(authorization.is_sensitive());
+        assert_eq!(authorization.as_bytes(), b"Bearer fixture-token");
+    }
+
+    #[test]
+    fn rejects_oversized_and_failed_credentials() {
+        let oversized = format!("printf '{}'", "x".repeat(MAX_TOKEN_BYTES + 1));
+        let (_temporary, executable) = executable_fixture(&oversized);
+        assert!(
+            discover_authorization(&executable, Instant::now() + Duration::from_secs(5)).is_none()
+        );
+
+        let (_temporary, executable) = executable_fixture("printf '%s\\n' 'ignored-token'; exit 7");
+        assert!(
+            discover_authorization(&executable, Instant::now() + Duration::from_secs(5)).is_none()
+        );
+    }
+
+    #[test]
+    fn deadline_terminates_the_owned_process_group() {
+        let (_temporary, executable) = executable_fixture(
+            r#"
+(
+    trap '' TERM
+    while :; do sleep 10; done
+) &
+descendant=$!
+printf '%s %s\n' "$$" "$descendant" > "$0.pids"
+wait "$descendant"
+"#,
+        );
+        let started = Instant::now();
+        assert!(
+            discover_authorization(&executable, started + Duration::from_millis(200),).is_none()
+        );
+        assert!(started.elapsed() < Duration::from_secs(1));
+
+        let pids = fs::read_to_string(format!("{}.pids", executable.display())).unwrap();
+        let pids = pids
+            .split_whitespace()
+            .map(|pid| pid.parse::<i32>().unwrap())
+            .collect::<Vec<_>>();
+        let cleanup_deadline = Instant::now() + Duration::from_secs(1);
+        while pids.iter().copied().any(process_is_running) && Instant::now() < cleanup_deadline {
+            std::thread::sleep(Duration::from_millis(10));
+        }
+        assert!(!pids.iter().copied().any(process_is_running));
+    }
+
+    fn executable_fixture(body: &str) -> (TempDir, PathBuf) {
+        let temporary = tempfile::tempdir().unwrap();
+        let executable = temporary.path().join("gh");
+        fs::write(&executable, format!("#!/bin/sh\nset -eu\n{body}\n")).unwrap();
+        let mut permissions = fs::metadata(&executable).unwrap().permissions();
+        permissions.set_mode(0o700);
+        fs::set_permissions(&executable, permissions).unwrap();
+        (temporary, executable)
+    }
+
+    fn process_is_running(pid: i32) -> bool {
+        let Ok(stat) = fs::read_to_string(format!("/proc/{pid}/stat")) else {
+            return false;
+        };
+        stat.rsplit_once(") ")
+            .and_then(|(_, fields)| fields.chars().next())
+            .is_some_and(|state| !matches!(state, 'Z' | 'X'))
+    }
+}