Add P55: JSON structured log format option to logd

When LOGD_JSON=1 is set in the environment, logd formats all log
lines as JSON objects with timestamp, source, and message fields.
Also fixes indentation issues in P51 logd rotation patch.

local/patches/base/P55-logd-json-format.patch

@@ -0,0 +1,115 @@
+--- a/logd/src/scheme.rs
++++ b/logd/src/scheme.rs
+@@ -5,6 +5,7 @@
+ use std::os::fd::{FromRawFd, RawFd};
+ use std::path::PathBuf;
+ use std::sync::mpsc::{self, Sender};
++use std::time::{SystemTime, UNIX_EPOCH};
+ 
+ use redox_scheme::scheme::SchemeSync;
+ use redox_scheme::{CallerCtx, OpenResult, SendFdRequest, Socket};
+@@ -38,6 +39,50 @@
+     AddSink(usize),
+ }
+ 
++fn json_escape(s: &str) -> String {
++    let mut out = String::with_capacity(s.len());
++    for c in s.chars() {
++        match c {
++            '\\' => out.push_str("\\\\"),
++            '"' => out.push_str("\\\""),
++            '\n' => out.push_str("\\n"),
++            '\r' => out.push_str("\\r"),
++            '\t' => out.push_str("\\t"),
++            c if c.is_control() => out.push_str(&format!("\\u{:04x}", c as u32)),
++            c => out.push(c),
++        }
++    }
++    out
++}
++
++fn format_json_line(context: &str, line: &[u8]) -> Vec<u8> {
++    let now = SystemTime::now()
++        .duration_since(UNIX_EPOCH)
++        .unwrap_or_default();
++    let secs = now.as_secs();
++    let timestamp = format!(
++        "{:04}-{:02}-{:02}T{:02}:{:02}:{:02}Z",
++        1970 + secs / 31_557_600,
++        (secs % 31_557_600) / 2_592_000 + 1,
++        (secs % 2_592_000) / 86_400 + 1,
++        (secs % 86_400) / 3600,
++        (secs % 3600) / 60,
++        secs % 60
++    );
++    let text = String::from_utf8_lossy(line).trim_end_matches('\n').to_string();
++    let (source, message) = match text.split_once(": ") {
++        Some((s, m)) => (s, m),
++        None => (context, text.as_str()),
++    };
++    let json = format!(
++        "{{\"timestamp\":\"{}\",\"source\":\"{}\",\"message\":\"{}\"}}\n",
++        json_escape(&timestamp),
++        json_escape(source),
++        json_escape(message)
++    );
++    json.into_bytes()
++}
++
+ struct LogFile {
+     file: File,
+     path: PathBuf,
+@@ -110,6 +155,8 @@
+             let _ = std::fs::create_dir_all(LOG_DIR);
+ 
+ 
++        let json_format = std::env::var("LOGD_JSON").map_or(false, |v| v == "1");
++
+         let (output_tx, output_rx) = mpsc::channel::<OutputCmd>();
+ 
+         std::thread::spawn(move || {
+@@ -123,9 +170,15 @@
+             for cmd in output_rx {
+                 match cmd {
+                     OutputCmd::Log { context, line } => {
++                        let out_line = if json_format {
++                            format_json_line(&context, &line)
++                        } else {
++                            line.clone()
++                        };
+                         if let Some(ref mut f) = persistent {
+-                            let _ = f.write(&line);
++                            let _ = f.write(&out_line);
+                             let _ = f.flush();
++                        }
+ 
+                         let service_name = context.split(':').next().unwrap_or("unknown");
+                         if !service_name.is_empty() {
+@@ -135,7 +188,7 @@
+                                     LogFile::open(PathBuf::from("/dev/null")).unwrap()
+                                 })
+                             });
+-                            let _ = entry.write(&line);
++                            let _ = entry.write(&out_line);
+                             let _ = entry.maybe_rotate();
+                         }
+ 
+@@ -145,15 +198,14 @@
+                                 LogFile::open(PathBuf::from("/dev/null")).unwrap()
+                             })
+                         });
+-                        let _ = system_entry.write(&line);
++                        let _ = system_entry.write(&out_line);
+                         let _ = system_entry.maybe_rotate();
+ 
+-                        }
+                         for file in &mut files {
+-                            let _ = file.write(&line);
++                            let _ = file.write(&out_line);
+                             let _ = file.flush();
+                         }
+-                        logs.push_back(line);
++                        logs.push_back(out_line);
+                         while logs.len() > MEMORY_LOG_LIMIT {
+                             logs.pop_front();
+                         }

recipes/core/base/P55-logd-json-format.patch

@@ -0,0 +1 @@
+../../../local/patches/base/P55-logd-json-format.patch

recipes/core/base/recipe.toml

@@ -111,6 +111,8 @@ patches = [
     "P52-acpid-cstates.patch",
     # P53: Add e1000d interrupt throttling rate (ITR) coalescing
     "P53-e1000d-itr-coalescing.patch",
+    # P55: Add JSON structured log format option to logd
+    "P55-logd-json-format.patch",
 ]
 
 [package]