fix non-signal-safe exit, and refactor signal handlers

1 files changed, 99 insertions, 0 deletions

diff --git a/src/signal/sigchld_handler.cc b/src/signal/sigchld_handler.cc
new file mode 100644
index 0000000..e11ed26
--- /dev/null
+++ b/src/signal/sigchld_handler.cc
@@ -0,0 +1,99 @@
+#include "signal_handler.h"
+
+#include <errno.h>
+
+namespace ov4
+{
+
+/* 
+ * sigchld_handler - The kernel sends a SIGCHLD to the shell whenever
+ *     a child job terminates (becomes a zombie), or stops because it
+ *     received a SIGSTOP or SIGTSTP signal. The handler reaps all
+ *     available zombie children, but doesn't wait for any other
+ *     currently running children to terminate.  
+ */
+void sigchld_handler([[maybe_unused]] int sig) 
+{
+    int errno_backup = errno;
+
+    sigset_t prev;
+    block_handler(&prev);
+
+    int status, pid;
+    safe_debug("SIGCHLD\n");
+
+    while ((pid = waitpid(-1, &status, WNOHANG | WUNTRACED)) > 0)
+    {
+        // signal'd or stopped or normally quit
+        // print terminated/stopped message
+        if (WIFSIGNALED(status) || WIFSTOPPED(status))
+        {
+            int jid = pid2jid(pid);
+            safe_output("Job [", jid, "] (", pid, ") ");
+            if (!WIFSTOPPED(status) && WTERMSIG(status) == SIGINT)
+                safe_print("terminated");
+            else if (WIFSTOPPED(status))
+                safe_print("stopped");
+            else 
+                safe_print("idk");
+            safe_print(" by signal ");
+            if (WIFSTOPPED(status))
+                safe_print(WSTOPSIG(status));
+            else
+                safe_print(WTERMSIG(status));
+            safe_print("\n");
+        } 
+
+        // handle job table
+        // and save exit/signal code
+
+        // stopped
+        if (WIFSTOPPED(status))
+        {
+            safe_output("Process suspended PID: ", pid, "\n");
+            sigset_t prev_inner;
+            block_all(&prev_inner);
+            job_suspend(pid);
+            sigprocmask(SIG_SETMASK, &prev_inner, nullptr);
+        }
+        // other type of signal'd
+        // or normally quit
+        else {
+            safe_output("Process terminated PID: ", pid, "\n");
+            sigset_t prev_inner;
+            block_all(&prev_inner);
+            deletejob(pid);
+            sigprocmask(SIG_SETMASK, &prev_inner, nullptr);
+
+            // terminated normally
+            // so that exit code should be available
+            if (WIFEXITED(status))
+            {
+                safe_output("Exit code: ", WEXITSTATUS(status), "\n");
+                if (pid == exit_required_pid)
+                {
+                    exit_code = WEXITSTATUS(status);
+                    safe_logger("sigchld_handler: required PID detected: ", pid, "\n");
+                }
+            }
+            // if signal'd
+            else if (WIFSIGNALED(status))
+            {
+                safe_output("Signal code: ", WTERMSIG(status), "\n");
+                if (pid == exit_required_pid)
+                {
+                    exit_code = SIGNAL_EXIT_CODE_BASE + WTERMSIG(status);
+                    safe_logger("sigchld_handler: required PID detected: ", pid, "\n");
+                }
+            }
+
+        }
+    }
+
+    sigprocmask(SIG_SETMASK, &prev, nullptr);
+
+    errno = errno_backup;
+    return;
+}
+
+}
\ No newline at end of file