Replace atty dependency with std::io::IsTerminal. (#4790)

The `atty` library has [a GitHub security
advisory](GHSA-g98v-hv3f-hcfr) noting that
it is unmaintained and can be unsound under some conditions. Its
functionality can be replaced with `std::io::IsTerminal`; this PR does
that.

I also added a helper function which replaces the two identical uses;
this gives a single place to change the policy if desired, rather than
perhaps accidentally editing only one site.

Cargo.toml

@@ -104,7 +104,6 @@ array-init = "2.1"
 arrow2 = "0.17"
 arrow2_convert = "0.5.0"
 async-executor = "1.0"
-atty = "0.2"
 backtrace = "0.3"
 bincode = "1.3"
 bitflags = { version = "2.4", features = ["bytemuck"] }

crates/re_sdk/Cargo.toml

@@ -52,7 +52,6 @@ re_sdk_comms = { workspace = true, features = ["client"] }
 re_types_core.workspace = true
 
 ahash.workspace = true
-atty.workspace = true
 crossbeam.workspace = true
 document-features.workspace = true
 once_cell.workspace = true

crates/re_sdk/src/recording_stream.rs

@@ -1,4 +1,5 @@
 use std::fmt;
+use std::io::IsTerminal;
 use std::sync::{atomic::AtomicI64, Arc};
 
 use ahash::HashMap;
@@ -37,6 +38,12 @@ fn forced_sink_path() -> Option<String> {
     std::env::var(ENV_FORCE_SAVE).ok()
 }
 
+/// Should we stream data to stdout when requested, or should we refrain because it's actually a
+/// terminal?
+fn is_stdout_listening() -> bool {
+    !std::io::stdout().is_terminal()
+}
+
 /// Errors that can occur when creating/manipulating a [`RecordingStream`].
 #[derive(thiserror::Error, Debug)]
 pub enum RecordingStreamError {
@@ -368,8 +375,7 @@ impl RecordingStreamBuilder {
     /// ```
     #[cfg(not(target_arch = "wasm32"))]
     pub fn stdout(self) -> RecordingStreamResult<RecordingStream> {
-        let is_stdout_listening = !atty::is(atty::Stream::Stdout);
-        if !is_stdout_listening {
+        if !is_stdout_listening() {
             return self.buffered();
         }
 
@@ -1409,8 +1415,7 @@ impl RecordingStream {
             return Ok(());
         }
 
-        let is_stdout_listening = !atty::is(atty::Stream::Stdout);
-        if !is_stdout_listening {
+        if !is_stdout_listening() {
             self.set_sink(Box::new(crate::log_sink::BufferedSink::new()));
             return Ok(());
         }