Instead of calling sigsuspend when waiting for SIGUSR[12] from parent,

install the signal handlers w/o SA_RESTART and let them interrupt waitpid().

diff --git a/script.c b/script.c
index 47ab3a2b6e3637b429700e780a3707e2b0558e45..7e27b6cd78b5bfb25e54caf495278a89ef9e0540 100644 (file)
--- a/script.c
+++ b/script.c
@@ -93,7 +93,7 @@ struct script_buf {
 static int script_fds[6];
 
 static sig_atomic_t alive = 1;
-static sig_atomic_t suspended = 0;
+static sig_atomic_t recvsig = 0;
 static sig_atomic_t foreground = 0;
 
 static sigset_t ttyblock;
@@ -109,7 +109,6 @@ static void sync_winsize __P((int src, int dst));
 static void handler __P((int s));
 static void sigchild __P((int s));
 static void sigcont __P((int s));
-static void sigfgbg __P((int s));
 static void sigrelay __P((int s));
 static void sigtstp __P((int s));
 static void sigwinch __P((int s));
@@ -532,7 +531,7 @@ script_execv(path, argv)
        if (input.len > input.off)
            FD_SET(script_fds[SFD_MASTER], fdsw);
 
-       switch (suspended) {
+       switch (recvsig) {
        case SIGTTOU:
        case SIGTTIN:
            /*
@@ -540,7 +539,7 @@ script_execv(path, argv)
             * Otherwise, re-send the signal with the handler disabled.
             */
            if (foreground) {
-               suspended = 0;
+               recvsig = 0;
                /* Set tty to raw mode and tell child it is in foregound. */
                do {
                    n = term_raw(script_fds[SFD_USERTTY], 1);
@@ -560,19 +559,19 @@ script_execv(path, argv)
 
            /* Suspend self and continue child when we resume. */
            sa.sa_handler = SIG_DFL;
-           sigaction(suspended, &sa, &osa);
+           sigaction(recvsig, &sa, &osa);
        suspend:
-           kill(parent, suspended);
+           kill(parent, recvsig);
 
            /*
             * If we were suspended due to tty I/O and sudo is still in
             * the background, re-suspend.
             */
-           if (!foreground && (suspended == SIGTTOU || suspended == SIGTTIN))
+           if (!foreground && (recvsig == SIGTTOU || recvsig == SIGTTIN))
                goto suspend;
 
-           sigaction(suspended, &osa, NULL);
-           suspended = 0;
+           sigaction(recvsig, &osa, NULL);
+           recvsig = 0;
            if (foreground) {
                /* Set tty to raw mode and tell child it is in foregound. */
                do {
@@ -713,15 +712,13 @@ script_child(path, argv, foreground, rbac_enabled)
     sigaction(SIGWINCH, &sa, NULL);
 
     /*
-     * Parent may sent signals that we need to pass on.
+     * Handle signals from parent and pass to child.
+     * We convert SIGUSR[12] to SIGCONT after special handling.
      */
     sa.sa_flags = 0; /* do not restart syscalls for these signals. */
     sa.sa_handler = handler;
     sigaction(SIGHUP, &sa, NULL);
     sigaction(SIGTERM, &sa, NULL);
-
-    /* Parent sends child SIGUSR1 to put command in the foreground. */
-    sa.sa_handler = sigfgbg;
     sigaction(SIGUSR1, &sa, NULL);
     sigaction(SIGUSR2, &sa, NULL);
 
@@ -782,10 +779,25 @@ script_child(path, argv, foreground, rbac_enabled)
            warning("tcsetpgrp");
     }
 
-    /* Wait for signal to arrive or for child to exit. */
+    /* Wait for signal to arrive or for child to stop/exit. */
     for (;;) {
-       if (suspended == SIGHUP || suspended == SIGTERM)
-           killpg(child, suspended);
+       switch (recvsig) {
+       case SIGHUP:
+       case SIGTERM:
+           /* signal child; we'll get its status when we continue. */
+           killpg(child, recvsig);
+           break;
+       case SIGUSR1:
+           /* foreground process, grant it controlling tty. */
+           do {
+               status = tcsetpgrp(script_fds[SFD_SLAVE], child);
+           } while (status == -1 && errno == EINTR);
+           /* FALLTHROUGH */
+       case SIGUSR2:
+           killpg(child, SIGCONT);
+           break;
+       }
+       recvsig = 0;
 
        pid = waitpid(child, &status, WUNTRACED);
        if (pid != child) {
@@ -802,29 +814,15 @@ script_child(path, argv, foreground, rbac_enabled)
        /*
         * Child was stopped by signal, signal parent and stop self.
         */
-       suspended = 0;
        signo = WSTOPSIG(status);
        do {
            /* Take back controlling tty while child is suspended. */
            status = tcsetpgrp(script_fds[SFD_SLAVE], self);
        } while (status == -1 && errno == EINTR);
        kill(parent, signo);
-
-       /*
-        * Wait for parent to resume us, then continue child.
-        */
-       do {
-           sigsuspend(&sa.sa_mask); 
-       } while (suspended == 0);
-       if (suspended == SIGUSR1) {
-           /* Command is in the foreground, grant it controlling tty. */
-           do {
-               status = tcsetpgrp(script_fds[SFD_SLAVE], child);
-           } while (status == -1 && errno == EINTR);
-       }
-       killpg(child, SIGCONT);
     }
 
+    /* Command is no longer running. */
     if (pid == child) {
        if (WIFEXITED(status)) {
            exitcode = WEXITSTATUS(status);
@@ -944,16 +942,6 @@ sigcont(s)
     errno = serrno;
 }
 
-/*
- * Signal handler for SIGUSR[12] in child
- */
-static void
-sigfgbg(s)
-    int s;
-{
-    suspended = s;
-}
-
 /*
  * Signal handler for child
  */
@@ -969,7 +957,7 @@ sigchild(s)
     } while (pid == -1 && errno == EINTR);
     if (pid == child) {
        if (WIFSTOPPED(child_status))
-           suspended = WSTOPSIG(child_status);
+           recvsig = WSTOPSIG(child_status);
        else
            alive = 0;
     }
@@ -984,7 +972,7 @@ static void
 handler(s)
     int s;
 {
-    suspended = s;
+    recvsig = s;
 }
 
 /*
@@ -1008,7 +996,7 @@ static void
 sigtstp(s)
     int s;
 {
-    suspended = s;
+    recvsig = s;
 }
 
 static void