X-Git-Url: https://git.jankratochvil.net/?p=nethome.git;a=blobdiff_plain;f=src%2Forphanripper.c;h=cf3039fddaf7a91e4642a8ec9df61ba36ac260e4;hp=cdf334912a18b1a1480046f244932dfe4d125f79;hb=f4cf3400508a136e366e2ce3dde132f5b1be7ac2;hpb=12128741f45224ae02b362e4acfd5a4683434f0c

diff --git a/src/orphanripper.c b/src/orphanripper.c
index cdf3349..cf3039f 100644
--- a/src/orphanripper.c
+++ b/src/orphanripper.c
@@ -24,6 +24,7 @@
  * 2007-07-10  Jan Kratochvil  <jan.kratochvil@redhat.com>
  */
 
+/* For getpgid(2).  */
 #define _GNU_SOURCE 1
 
 #include <stdio.h>
@@ -41,13 +42,25 @@
 #include <pty.h>
 #include <poll.h>
 
+#define LENGTH(x) (sizeof (x) / sizeof (*(x)))
+
 static const char *progname;
 
 static volatile int signal_child_hit = 0;
 
+/* We use it to race-safely emulate ppoll(2) by poll(2).  */
+static int pipefd[2];
+
 static void signal_child (int signo)
 {
+  int i;
+
   signal_child_hit = 1;
+
+  assert (pipefd[1] != -1);
+  i = close (pipefd[1]);
+  assert (i == 0);
+  pipefd[1] = -1;
 }
 
 static char childptyname[LINE_MAX];
@@ -58,34 +71,46 @@ static int spawn (char **argv)
   pid_t child_got;
   int status, amaster, i;
   struct sigaction act;
-  sigset_t sigset;
+  struct termios termios;
 
-  /* Never miss SIGCHLD.  */
-  i = sigemptyset (&sigset);
-  assert (i == 0);
-  i = sigaddset (&sigset, SIGCHLD);
-  assert (i == 0);
-  i = sigprocmask (SIG_BLOCK, &sigset, NULL);
-  assert (i == 0);
-  i = sigemptyset (&sigset);
+  i = pipe (pipefd);
   assert (i == 0);
 
-  /* We do not use signal(2) to be sure we have SA_RESTART unset.  */
+  /* We do not use signal(2) to be sure we have SA_RESTART set.  */
   memset (&act, 0, sizeof (act));
   act.sa_handler = signal_child;
   i = sigemptyset (&act.sa_mask);
   assert (i == 0);
-  act.sa_flags = 0;
+  act.sa_flags = SA_RESTART;
   i = sigaction (SIGCHLD, &act, NULL);
   assert (i == 0);
 
-  child = forkpty (&amaster, childptyname, NULL, NULL);
+  /* With TERMP passed as NULL we get "\n" -> "\r\n".  */
+  cfmakeraw (&termios);
+#ifdef FLUSHO
+  /* Workaround a readline deadlock bug in _get_tty_settings().  */
+  termios.c_lflag &= ~FLUSHO;
+#endif
+  child = forkpty (&amaster, childptyname, &termios, NULL);
   switch (child)
     {
       case -1:
 	perror ("forkpty(3)");
 	exit (EXIT_FAILURE);
       case 0:
+	i = close (pipefd[0]);
+	assert (i == 0);
+	i = close (pipefd[1]);
+	assert (i == 0);
+
+	/* Do not replace STDIN as inferiors query its termios.  */
+#if 0
+	i = close (STDIN_FILENO);
+	assert (i == 0);
+	i = open ("/dev/null", O_RDONLY);
+	assert (i == STDIN_FILENO);
+#endif
+
 	/* Do not setpgrp(2) in the parent process as the process-group
 	   is shared for the whole sh(1) pipeline we could be a part
 	   of.  The process-group is set according to PID of the first
@@ -116,42 +141,48 @@ static int spawn (char **argv)
     }
   for (;;)
     {
-      struct pollfd pollfd;
+      struct pollfd pollfd[2];
       char buf[LINE_MAX];
       ssize_t buf_got;
 
-      pollfd.fd = amaster;
-      pollfd.events = POLLIN;
-      i = ppoll (&pollfd, 1, NULL, &sigset);
-      assert (i == -1 || i == 1);
-      if (i == -1)
-        {
-	  assert (errno == EINTR && signal_child_hit != 0);
-	  break;
-	}
-      /* i == 1 */
-      assert (pollfd.revents != 0);
-      if (pollfd.revents & POLLHUP)
-        break;
-      if (pollfd.revents != POLLIN)
+      pollfd[0].fd = amaster;
+      pollfd[0].events = POLLIN;
+      pollfd[1].fd = pipefd[0];
+      pollfd[1].events = POLLIN;
+      i = poll (pollfd, LENGTH (pollfd), -1);
+      if (i == -1 && errno == EINTR)
         {
-	  fprintf (stderr, "%s: ppoll(2): revents 0x%x\n", progname,
-		   (unsigned) pollfd.revents);
-	  exit (EXIT_FAILURE);
+	  /* Weird but SA_RESTART sometimes does not work.  */
+	  continue;
 	}
-      buf_got = read (amaster, buf, sizeof buf);
-      if (buf_got == 0)
-	break;
-      if (buf_got == -1)
+      assert (i >= 1);
+      /* Data available?  Process it first.  */
+      if (pollfd[0].revents & POLLIN)
 	{
-	  perror ("read (amaster)");
-	  exit (EXIT_FAILURE);
+	  buf_got = read (amaster, buf, sizeof buf);
+	  if (buf_got <= 0)
+	    {
+	      perror ("read (amaster)");
+	      exit (EXIT_FAILURE);
+	    }
+	  if (write (STDOUT_FILENO, buf, buf_got) != buf_got)
+	    {
+	      perror ("write(2)");
+	      exit (EXIT_FAILURE);
+	    }
 	}
-      if (write (STDOUT_FILENO, buf, buf_got) != buf_got)
+      if (pollfd[0].revents & POLLHUP)
+        break;
+      if ((pollfd[0].revents &= ~POLLIN) != 0)
 	{
-	  perror ("write(2)");
+	  fprintf (stderr, "%s: ppoll(2): revents 0x%x\n", progname,
+		   (unsigned) pollfd[0].revents);
 	  exit (EXIT_FAILURE);
 	}
+      /* Child exited?  */
+      if (pollfd[1].revents & POLLHUP)
+	break;
+      assert (pollfd[1].revents == 0);
     }
   /* WNOHANG still could fail.  */
   child_got = waitpid (child, &status, 0);
@@ -165,6 +196,12 @@ static int spawn (char **argv)
       fprintf (stderr, "waitpid (%d): !WIFEXITED (%d)\n", (int) child, status);
       exit (EXIT_FAILURE);
     }
+
+  assert (signal_child_hit != 0);
+  assert (pipefd[1] == -1);
+  i = close (pipefd[0]);
+  assert (i == 0);
+
   /* Do not close the master FD as the child would have `/dev/pts/23 (deleted)'
      entries which are not expected (and expecting ` (deleted)' would be
      a race.  */