Handle platform differences and propagate sigterm

This commit handles sigterm explicitly,and implements the different
sigterm propagation based on windows vs unix systems. This commit
does not provide a windows implementation for handling sigterm.

Affected paths are project/run and tool/run

crates/uv/Cargo.toml

@@ -97,6 +97,7 @@ url = { workspace = true }
 walkdir = { workspace = true }
 which = { workspace = true }
 zip = { workspace = true }
+cfg-if = "1.0"
 
 [dev-dependencies]
 assert_cmd = { version = "2.0.16" }
@@ -115,6 +116,9 @@ similar = { version = "2.6.0" }
 tempfile = { workspace = true }
 zip = { workspace = true }
 
+[target.'cfg(unix)'.dependencies]
+nix = "0.23"
+
 [package.metadata.cargo-shear]
 ignored = [
     "flate2",

crates/uv/src/commands/project/run.rs

@@ -7,10 +7,11 @@ use std::path::{Path, PathBuf};
 
 use anstream::eprint;
 use anyhow::{anyhow, bail, Context};
+use cfg_if::cfg_if;
 use futures::StreamExt;
 use itertools::Itertools;
 use owo_colors::OwoColorize;
-use tokio::process::Command;
+use tokio::process::{Child, Command};
 use tracing::{debug, warn};
 use url::Url;
 use uv_cache::Cache;
@@ -996,9 +997,27 @@ pub(crate) async fn run(
     // signal handlers after the command completes.
     let _handler = tokio::spawn(async { while tokio::signal::ctrl_c().await.is_ok() {} });
 
-    let status = handle.wait().await.context("Child process disappeared")?;
+    #[cfg(unix)]
+    {
+        use tokio::select;
+        use tokio::signal::unix::{signal, SignalKind};
+        let mut term_signal = signal(SignalKind::terminate())?;
+        loop {
+            select! {
+                _ = handle.wait() => {
+                    break
+                },
+
+                // `SIGTERM`
+                _ = term_signal.recv() => {
+                    let _ = terminate_process(&mut handle);
+                }
+            };
+        }
+    }
 
     // Exit based on the result of the command
+    let status = handle.wait().await?;
     if let Some(code) = status.code() {
         debug!("Command exited with code: {code}");
         if let Ok(code) = u8::try_from(code) {
@@ -1017,6 +1036,22 @@ pub(crate) async fn run(
     }
 }
 
+#[allow(clippy::items_after_statements, dead_code)]
+fn terminate_process(_child: &mut Child) -> Result<(), anyhow::Error> {
+    cfg_if! {
+        if #[cfg(unix)] {
+            let pid = _child.id().context("Failed to get child process ID")?;
+            use nix::sys::signal::{self, Signal};
+            use nix::unistd::Pid;
+            signal::kill(Pid::from_raw(pid.try_into().unwrap()), Signal::SIGTERM)
+                .context("Failed to send SIGTERM")
+        } else if #[cfg(windows)] {
+            // On Windows, use winapi to terminate the process gracefully
+            todo!("Implement graceful termination on Windows");
+        }
+    }
+}
+
 /// Returns `true` if we can skip creating an additional ephemeral environment in `uv run`.
 fn can_skip_ephemeral(
     spec: Option<&RequirementsSpecification>,

crates/uv/src/commands/tool/run.rs

@@ -1,3 +1,4 @@
+use cfg_if::cfg_if;
 use std::fmt::Display;
 use std::fmt::Write;
 use std::path::PathBuf;
@@ -7,9 +8,8 @@ use anstream::eprint;
 use anyhow::{bail, Context};
 use itertools::Itertools;
 use owo_colors::OwoColorize;
+use tokio::process::Child;
 use tokio::process::Command;
-use tokio::select;
-use tokio::signal::unix::{signal, SignalKind};
 use tracing::{debug, warn};
 
 use uv_cache::{Cache, Refresh};
@@ -238,30 +238,27 @@ pub(crate) async fn run(
     // signal handlers after the command completes.
     let _handler = tokio::spawn(async { while tokio::signal::ctrl_c().await.is_ok() {} });
 
-    let mut term_signal = signal(SignalKind::terminate())?;
-    let mut int_signal = signal(SignalKind::interrupt())?;
-
-    let status = select! {
-        status = handle.wait() => status,
-
-        // `SIGTERM`
-        _ = term_signal.recv() => {
-            handle.kill().await?;
-            handle.wait().await.context("Child process disappeared")?;
-            return Ok(ExitStatus::Failure);
-        }
-
-        // `SIGINT`
-        _ = int_signal.recv() => {
-            handle.kill().await?;
-            handle.wait().await.context("Child process disappeared")?;
-            return Ok(ExitStatus::Failure);
+    #[cfg(unix)]
+    {
+        use tokio::select;
+        use tokio::signal::unix::{signal, SignalKind};
+        let mut term_signal = signal(SignalKind::terminate())?;
+        loop {
+            select! {
+                _ = handle.wait() => {
+                    break
+                },
+
+                // `SIGTERM`
+                _ = term_signal.recv() => {
+                    let _ = terminate_process(&mut handle);
+                }
+            };
         }
-    };
-
-    let status = status.context("Child process disappeared")?;
+    }
 
     // Exit based on the result of the command
+    let status = handle.wait().await?;
     if let Some(code) = status.code() {
         debug!("Command exited with code: {code}");
         if let Ok(code) = u8::try_from(code) {
@@ -280,6 +277,23 @@ pub(crate) async fn run(
     }
 }
 
+#[allow(clippy::items_after_statements, dead_code)]
+fn terminate_process(_child: &mut Child) -> Result<(), anyhow::Error> {
+    cfg_if! {
+        if #[cfg(unix)] {
+            let pid = _child.id().context("Failed to get child process ID")?;
+            // On Unix, send SIGTERM for a graceful shutdown
+            use nix::sys::signal::{self, Signal};
+            use nix::unistd::Pid;
+            signal::kill(Pid::from_raw(pid.try_into().unwrap()), Signal::SIGTERM)
+                .context("Failed to send SIGTERM")
+        } else if #[cfg(windows)] {
+            // On Windows, use winapi to terminate the process gracefully
+            todo!("Implement graceful termination on Windows");
+        }
+    }
+}
+
 /// Return the entry points for the specified package.
 fn get_entrypoints(
     from: &PackageName,