Fix function pointer cast lint errors across crates

Author: jgarzik

cron/crond.rs

@@ -240,10 +240,10 @@ fn main() -> Result<(), Box<dyn Error>> {
     // extern "C" function handlers. All handlers are async-signal-safe
     // (they only perform atomic stores or call async-signal-safe functions).
     unsafe {
-        libc::signal(libc::SIGHUP, handle_sighup as usize);
-        libc::signal(libc::SIGCHLD, handle_sigchld as usize);
-        libc::signal(libc::SIGTERM, handle_shutdown as usize);
-        libc::signal(libc::SIGINT, handle_shutdown as usize);
+        libc::signal(libc::SIGHUP, handle_sighup as *const () as usize);
+        libc::signal(libc::SIGCHLD, handle_sigchld as *const () as usize);
+        libc::signal(libc::SIGTERM, handle_shutdown as *const () as usize);
+        libc::signal(libc::SIGINT, handle_shutdown as *const () as usize);
     }
 
     // Run @reboot jobs at startup

file/dd.rs

@@ -622,7 +622,10 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     // Install SIGINT handler
     unsafe {
-        libc::signal(libc::SIGINT, sigint_handler as libc::sighandler_t);
+        libc::signal(
+            libc::SIGINT,
+            sigint_handler as *const () as libc::sighandler_t,
+        );
     }
 
     let args: Vec<String> = std::env::args().skip(1).collect();

users/talk.rs

@@ -1821,7 +1821,7 @@ pub fn register_signals() {
 
         // Register the `handle_signals` function for each signal
         for &sig in signals {
-            if signal(sig, handle_signals as usize) == libc::SIG_ERR {
+            if signal(sig, handle_signals as *const () as usize) == libc::SIG_ERR {
                 eprintln!("Failed to register signal handler for signal {}", sig);
             }
         }

users/talkd.rs

@@ -494,9 +494,18 @@ extern "C" fn handle_signal(_sig: libc::c_int) {
 fn register_signals(socket_path: &Path) {
     unsafe {
         SOCKET_PATH = Some(socket_path.to_path_buf());
-        libc::signal(libc::SIGINT, handle_signal as libc::sighandler_t);
-        libc::signal(libc::SIGTERM, handle_signal as libc::sighandler_t);
-        libc::signal(libc::SIGQUIT, handle_signal as libc::sighandler_t);
+        libc::signal(
+            libc::SIGINT,
+            handle_signal as *const () as libc::sighandler_t,
+        );
+        libc::signal(
+            libc::SIGTERM,
+            handle_signal as *const () as libc::sighandler_t,
+        );
+        libc::signal(
+            libc::SIGQUIT,
+            handle_signal as *const () as libc::sighandler_t,
+        );
     }
 }
 

users/write.rs

@@ -249,7 +249,11 @@ extern "C" fn handle_sigint(_sig: libc::c_int) {
 /// Register signal handler for SIGINT
 fn register_sigint_handler() {
     unsafe {
-        if libc::signal(libc::SIGINT, handle_sigint as libc::sighandler_t) == libc::SIG_ERR {
+        if libc::signal(
+            libc::SIGINT,
+            handle_sigint as *const () as libc::sighandler_t,
+        ) == libc::SIG_ERR
+        {
             eprintln!("{}", gettext("Failed to register signal handler"));
         }
     }