refactor(library-config): reorganize Linux process context

Author: cataphract

libdd-library-config-ffi/Cargo.toml

@@ -14,7 +14,7 @@ bench = false
 [dependencies]
 libdd-common = { path = "../libdd-common" }
 libdd-common-ffi = { path = "../libdd-common-ffi", default-features = false }
-libdd-library-config = { path = "../libdd-library-config" }
+libdd-library-config = { path = "../libdd-library-config", default-features = false, features = ["process-context-writer"] }
 anyhow = "1.0"
 constcat = "0.4.1"
 

libdd-library-config/Cargo.toml

@@ -15,7 +15,10 @@ crate-type = ["lib"]
 bench = false
 
 [features]
-otel-thread-ctx = []
+default = ["process-context-reader", "process-context-writer"]
+otel-thread-ctx = ["process-context-writer"]
+process-context-reader = []
+process-context-writer = []
 
 [dependencies]
 serde = { version = "1.0", features = ["derive"] }

libdd-library-config/src/lib.rs

@@ -2,6 +2,10 @@
 // SPDX-License-Identifier: Apache-2.0
 extern crate alloc;
 
+#[cfg(all(
+    target_os = "linux",
+    any(feature = "process-context-reader", feature = "process-context-writer")
+))]
 pub mod otel_process_ctx;
 pub mod tracer_metadata;
 

libdd-library-config/src/otel_process_ctx.rs

@@ -0,0 +1,22 @@
+// Copyright 2026-Present Datadog, Inc. https://www.datadoghq.com/
+// SPDX-License-Identifier: Apache-2.0
+
+use core::ffi::CStr;
+
+#[cfg(feature = "process-context-reader")]
+pub mod self_reader {
+    pub use crate::otel_process_ctx::ProcessContextSelfReader;
+}
+
+// Re-exported for backwards compatibility.
+#[cfg(feature = "process-context-writer")]
+#[deprecated(note = "use libdd_library_config::otel_process_ctx directly")]
+pub use super::{publish, unpublish};
+#[deprecated(note = "use libdd_library_config::otel_process_ctx directly")]
+pub use super::{PROCESS_CTX_VERSION, SIGNATURE};
+#[cfg(feature = "process-context-reader")]
+#[deprecated(note = "use libdd_library_config::otel_process_ctx::ProcessContextSelfReader")]
+pub use self_reader::ProcessContextSelfReader;
+
+/// The discoverable name of the memory mapping.
+pub const MAPPING_NAME: &CStr = c"OTEL_CTX";