refactor(symfony-process): drop the --enable-sigchild workarounds

isSigchildEnabled() detects a PHP built with --enable-sigchild, where PHP
reaps children itself and proc_get_status()/proc_terminate() stop reporting
or reaching them. Shirabe spawns child processes from Rust, so that build
option cannot affect them and every sigchild branch was unreachable.

Removing the branches retires the state that existed only to feed them:
fallbackStatus (written by the fourth pipe and by doSignal, read only by
the sigchild merge in updateStatus) and useFileHandles (whose sole reader
was the sigchild condition). shirabe-php-shim loses phpinfo(),
INFO_GENERAL and posix_kill(), which had no other callers.

DiagnoseCommand keeps its --enable-sigchild warning: it reports on the
user's PHP installation, not on how Shirabe runs processes.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

4 files changed, 17 insertions, 157 deletions

diff --git a/crates/shirabe-php-shim/src/output.rs b/crates/shirabe-php-shim/src/output.rs
index 698f3bf4..d4d83200 100644
--- a/crates/shirabe-php-shim/src/output.rs
+++ b/crates/shirabe-php-shim/src/output.rs
@@ -1,6 +1,5 @@
 // PHP output buffering captures everything the interpreter would echo to stdout. The shim has no
-// general echo-to-buffer routing, and its only producer in Composer (`phpinfo`) depends on PHP
-// runtime configuration that is itself unmodeled, so a buffer here would silently capture nothing.
+// general echo-to-buffer routing, so a buffer here would silently capture nothing.
 pub fn ob_start() -> bool {
     todo!()
 }
diff --git a/crates/shirabe-php-shim/src/process.rs b/crates/shirabe-php-shim/src/process.rs
index 2b380c60..b082f472 100644
--- a/crates/shirabe-php-shim/src/process.rs
+++ b/crates/shirabe-php-shim/src/process.rs
@@ -380,12 +380,7 @@ pub fn proc_terminate(process: &PhpResource, signal: i64) -> bool {
     let Some(child) = state.child.as_ref() else {
         return false;
     };
-    send_signal(child.id() as i32, signal)
-}
-
-/// Shared body of `proc_terminate` and `posix_kill`. Signal 0 is PHP's existence probe and is
-/// forwarded to `kill(2)` as such.
-fn send_signal(pid: i32, signal: i64) -> bool {
+    // Signal 0 is PHP's existence probe and is forwarded to `kill(2)` as such.
     let signal = if signal == 0 {
         None
     } else {
@@ -394,7 +389,7 @@ fn send_signal(pid: i32, signal: i64) -> bool {
             Err(_) => return false,
         }
     };
-    nix::sys::signal::kill(nix::unistd::Pid::from_raw(pid), signal).is_ok()
+    nix::sys::signal::kill(nix::unistd::Pid::from_raw(child.id() as i32), signal).is_ok()
 }
 
 pub fn getmypid() -> i64 {
@@ -466,10 +461,6 @@ pub fn posix_isatty(stream: PhpResource) -> bool {
     }
 }
 
-pub fn posix_kill(pid: i64, signal: i64) -> bool {
-    send_signal(pid as i32, signal)
-}
-
 /// PHP `get_current_user()`: the name of the owner of the running script file. The Shirabe
 /// executable takes the place of the script; PHP returns an empty string when the lookup fails.
 pub fn get_current_user() -> String {
diff --git a/crates/shirabe-php-shim/src/runtime.rs b/crates/shirabe-php-shim/src/runtime.rs
index 86cbfd74..2b5e7155 100644
--- a/crates/shirabe-php-shim/src/runtime.rs
+++ b/crates/shirabe-php-shim/src/runtime.rs
@@ -27,7 +27,6 @@ pub const E_USER_NOTICE: i64 = 1024;
 pub const E_DEPRECATED: i64 = 8192;
 pub const E_USER_DEPRECATED: i64 = 16384;
 
-pub const INFO_GENERAL: i64 = 1;
 pub const PHP_BINARY: &str = "";
 
 // NOTE: &str matching in const expression does not compile for now.
@@ -366,12 +365,6 @@ pub fn ini_set(_varname: &str, _value: &str) -> Option<String> {
     todo!()
 }
 
-pub fn phpinfo(_what: i64) {
-    // TODO(php-runtime): phpinfo() dumps the full PHP runtime configuration, which the shim does not
-    // model.
-    todo!()
-}
-
 pub fn sapi_windows_vt100_support(_resource: &crate::PhpResource) -> bool {
     // TODO(phase-c): Windows-only SAPI function; not defined on the non-Windows target this build
     // models (function_exists reports it absent).
diff --git a/crates/shirabe-symfony-process/src/process.rs b/crates/shirabe-symfony-process/src/process.rs
index 1dfb5806..b7459d41 100644
--- a/crates/shirabe-symfony-process/src/process.rs
+++ b/crates/shirabe-symfony-process/src/process.rs
@@ -51,7 +51,6 @@ pub struct Process {
     starttime: Option<f64>,
     timeout: Option<f64>,
     exitcode: Option<i64>,
-    fallback_status: IndexMap<String, PhpMixed>,
     process_information: Option<IndexMap<String, PhpMixed>>,
     stdout: Option<PhpResource>,
     stderr: Option<PhpResource>,
@@ -61,7 +60,6 @@ pub struct Process {
     incremental_error_output_offset: i64,
     tty: bool,
     options: IndexMap<String, PhpMixed>,
-    use_file_handles: bool,
     process_pipes: Option<Box<dyn PipesInterface>>,
     latest_signal: Option<i64>,
     cached_exit_code: Option<i64>,
@@ -180,7 +178,6 @@ impl Process {
             starttime: None,
             timeout: None,
             exitcode: None,
-            fallback_status: IndexMap::new(),
             process_information: None,
             stdout: None,
             stderr: None,
@@ -190,7 +187,6 @@ impl Process {
             incremental_error_output_offset: 0,
             tty: false,
             options,
-            use_file_handles: false,
             process_pipes: None,
             latest_signal: None,
             cached_exit_code: None,
@@ -245,7 +241,6 @@ impl Process {
 
         this.set_input(input)?;
         this.set_timeout(timeout)?;
-        this.use_file_handles = cfg!(windows);
 
         Ok(this)
     }
@@ -288,7 +283,7 @@ impl Process {
         self.reset_process_data();
         self.starttime = Some(shirabe_php_shim::microtime());
         self.callback = Some(self.build_callback(callback));
-        let mut descriptors = self.get_descriptors();
+        let descriptors = self.get_descriptors();
 
         if !self.env.is_empty() {
             // non-Windows: $env += $this->env;
@@ -320,17 +315,6 @@ impl Process {
 
         if cfg!(windows) {
             commandline = self.prepare_windows_command_line(&commandline, &mut env)?;
-        } else if !self.use_file_handles && self.is_sigchild_enabled() {
-            // last exit code is output on the fourth pipe and caught to work around --enable-sigchild
-            descriptors.push(descriptor(&["pipe", "w"]));
-
-            commandline = format!("{{ ({}) <&3 3<&- 3>/dev/null & }} 3<&0;", commandline);
-            commandline.push_str(
-                "pid=$!; echo $pid >&3; wait $pid 2>/dev/null; code=$?; echo $code >&3; exit $code",
-            );
-
-            // Workaround for the bug, when PTS functionality is enabled.
-            let _pts_workaround = shirabe_php_shim::fopen("Process.php", "r");
         }
 
         let mut env_pairs: Vec<String> = Vec::new();
@@ -376,22 +360,6 @@ impl Process {
         }
         self.status = Self::STATUS_STARTED.to_string();
 
-        if descriptors.len() > 3 {
-            let pipe3 = self
-                .process_pipes
-                .as_ref()
-                .unwrap()
-                .pipes()
-                .get(&3)
-                .cloned();
-            let pid = pipe3
-                .and_then(|p| shirabe_php_shim::fgets(&p, None))
-                .map(|s| s.trim().parse::<i64>().unwrap_or(0))
-                .unwrap_or(0);
-            self.fallback_status
-                .insert("pid".to_string(), PhpMixed::Int(pid));
-        }
-
         if self.tty {
             return Ok(());
         }
@@ -515,19 +483,12 @@ impl Process {
     pub fn get_term_signal(&mut self) -> anyhow::Result<i64> {
         self.require_process_is_terminated("getTermSignal")?;
 
-        let termsig = self
+        Ok(self
             .process_information
             .as_ref()
             .and_then(|i| i.get("termsig"))
-            .and_then(|v| v.as_int());
-        if self.is_sigchild_enabled() && termsig == Some(-1) {
-            return Err(RuntimeException::new(
-                "This PHP has been compiled with --enable-sigchild. Term signal cannot be retrieved.".to_string(),
-            )
-            .into());
-        }
-
-        Ok(termsig.unwrap_or(0))
+            .and_then(|v| v.as_int())
+            .unwrap_or(0))
     }
 
     /// Checks if the process is currently running.
@@ -579,11 +540,6 @@ impl Process {
         }
 
         if self.is_running() {
-            if self.fallback_status.contains_key("pid") {
-                self.fallback_status.shift_remove("pid");
-
-                return self.stop(0.0, signal);
-            }
             self.close();
         }
 
@@ -814,43 +770,11 @@ impl Process {
 
         self.read_pipes(running && blocking, !cfg!(windows) || !running);
 
-        if !self.fallback_status.is_empty() && self.is_sigchild_enabled() {
-            // processInformation = fallbackStatus + processInformation (fallback keys win)
-            let mut merged = self.fallback_status.clone();
-            for (k, v) in self.process_information.take().unwrap() {
-                merged.entry(k).or_insert(v);
-            }
-            self.process_information = Some(merged);
-        }
-
         if !running {
             self.close();
         }
     }
 
-    /// Returns whether PHP has been compiled with the '--enable-sigchild' option or not.
-    fn is_sigchild_enabled(&self) -> bool {
-        static SIGCHILD: OnceLock<bool> = OnceLock::new();
-
-        if let Some(v) = SIGCHILD.get() {
-            return *v;
-        }
-
-        if !shirabe_php_shim::function_exists("phpinfo") {
-            return *SIGCHILD.get_or_init(|| false);
-        }
-
-        shirabe_php_shim::ob_start();
-        shirabe_php_shim::phpinfo(shirabe_php_shim::INFO_GENERAL);
-
-        *SIGCHILD.get_or_init(|| {
-            shirabe_php_shim::str_contains(
-                &shirabe_php_shim::ob_get_clean().unwrap_or_default(),
-                "--enable-sigchild",
-            )
-        })
-    }
-
     /// Reads pipes for the freshest output.
     fn read_pipes_for_output(&mut self, caller: &str, blocking: bool) -> anyhow::Result<()> {
         self.require_process_is_started(caller)?;
@@ -885,22 +809,15 @@ impl Process {
 
         let mut callback = self.callback.take();
         for (r#type, data) in result {
-            if r#type != 3 {
-                if let Some(cb) = callback.as_mut() {
-                    cb(
-                        self,
-                        if Self::STDOUT == r#type {
-                            Self::OUT
-                        } else {
-                            Self::ERR
-                        },
-                        &data,
-                    );
-                }
-            } else if !self.fallback_status.contains_key("signaled") {
-                self.fallback_status.insert(
-                    "exitcode".to_string(),
-                    PhpMixed::Int(data.trim().parse().unwrap_or(0)),
+            if let Some(cb) = callback.as_mut() {
+                cb(
+                    self,
+                    if Self::STDOUT == r#type {
+                        Self::OUT
+                    } else {
+                        Self::ERR
+                    },
+                    &data,
                 );
             }
         }
@@ -939,11 +856,6 @@ impl Process {
             if signaled && termsig > 0 {
                 // if process has been signaled, no exitcode but a valid termsig, apply Unix convention
                 self.exitcode = Some(128 + termsig);
-            } else if self.is_sigchild_enabled()
-                && let Some(i) = self.process_information.as_mut()
-            {
-                i.insert("signaled".to_string(), PhpMixed::Bool(true));
-                i.insert("termsig".to_string(), PhpMixed::Int(-1));
             }
         }
 
@@ -958,7 +870,6 @@ impl Process {
         self.starttime = None;
         self.callback = None;
         self.exitcode = None;
-        self.fallback_status = IndexMap::new();
         self.process_information = None;
         // php://temp is an in-memory stream; fopen never fails for it.
         self.stdout = Some(
@@ -1012,33 +923,7 @@ impl Process {
                 return Ok(false);
             }
         } else {
-            let ok;
-            if !self.is_sigchild_enabled() {
-                ok = shirabe_php_shim::proc_terminate(self.process.as_ref().unwrap(), signal);
-            } else if shirabe_php_shim::function_exists("posix_kill") {
-                ok = shirabe_php_shim::posix_kill(pid, signal);
-            } else {
-                let mut pipes = IndexMap::new();
-                let opened = shirabe_php_shim::proc_open(
-                    &format!("kill -{} {}", signal, pid),
-                    &[
-                        Descriptor::Inherit,
-                        Descriptor::Inherit,
-                        descriptor(&["pipe", "w"]),
-                    ],
-                    &mut pipes,
-                    None,
-                    None,
-                    None,
-                );
-                ok = match opened {
-                    Ok(_) => pipes
-                        .get(&2)
-                        .and_then(|p| shirabe_php_shim::fgets(p, None))
-                        .is_none(),
-                    Err(_) => false,
-                };
-            }
+            let ok = shirabe_php_shim::proc_terminate(self.process.as_ref().unwrap(), signal);
             if !ok {
                 if throw_exception {
                     return Err(RuntimeException::new(format!(
@@ -1053,14 +938,6 @@ impl Process {
         }
 
         self.latest_signal = Some(signal);
-        self.fallback_status
-            .insert("signaled".to_string(), PhpMixed::Bool(true));
-        self.fallback_status
-            .insert("exitcode".to_string(), PhpMixed::Int(-1));
-        self.fallback_status.insert(
-            "termsig".to_string(),
-            PhpMixed::Int(self.latest_signal.unwrap()),
-        );
 
         Ok(true)
     }