GUnixInput/OutputStream: fix blocking methods to always block

Previously, if you created a GUnixInputStream or GUnixOutputStream
from a non-blocking file descriptor, it might sometimes return
G_IO_ERROR_WOULD_BLOCK from g_input_stream_read/g_output_stream_write,
which is wrong. Fix that. (Use the GPollableInput/OutputStream methods
if you want non-blocking I/O.)

Also, add a test for this to gio/tests/unix-streams.

Also, fix the GError messages to say "Error reading from file
descriptor", etc instead of "Error reading from unix" (which was
presumably from a bad search and replace job).

https://bugzilla.gnome.org/show_bug.cgi?id=626866

gio/gunixinputstream.c

@@ -361,21 +361,27 @@ g_unix_input_stream_read (GInputStream  *stream,
 			  GError       **error)
 {
   GUnixInputStream *unix_stream;
-  gssize res;
+  gssize res = -1;
   GPollFD poll_fds[2];
+  int nfds;
   int poll_ret;
 
   unix_stream = G_UNIX_INPUT_STREAM (stream);
 
+  poll_fds[0].fd = unix_stream->priv->fd;
+  poll_fds[0].events = G_IO_IN;
   if (unix_stream->priv->is_pipe_or_socket &&
       g_cancellable_make_pollfd (cancellable, &poll_fds[1]))
+    nfds = 2;
+  else
+    nfds = 1;
+
+  while (1)
     {
-      poll_fds[0].fd = unix_stream->priv->fd;
+      poll_fds[0].revents = poll_fds[1].revents = 0;
-      poll_fds[0].events = G_IO_IN;
       do
-	poll_ret = g_poll (poll_fds, 2, -1);
+	poll_ret = g_poll (poll_fds, nfds, -1);
       while (poll_ret == -1 && errno == EINTR);
-      g_cancellable_release_fd (cancellable);
 
       if (poll_ret == -1)
 	{
@@ -383,33 +389,35 @@ g_unix_input_stream_read (GInputStream  *stream,
 
 	  g_set_error (error, G_IO_ERROR,
 		       g_io_error_from_errno (errsv),
-		       _("Error reading from unix: %s"),
+		       _("Error reading from file descriptor: %s"),
 		       g_strerror (errsv));
-	  return -1;
+	  break;
 	}
-    }
 
-  while (1)
-    {
       if (g_cancellable_set_error_if_cancelled (cancellable, error))
-	return -1;
+	break;
+
+      if (!poll_fds[0].revents)
+	continue;
+
       res = read (unix_stream->priv->fd, buffer, count);
       if (res == -1)
 	{
           int errsv = errno;
 
-	  if (errsv == EINTR)
+	  if (errsv == EINTR || errsv == EAGAIN)
 	    continue;
-	  
+
 	  g_set_error (error, G_IO_ERROR,
 		       g_io_error_from_errno (errsv),
-		       _("Error reading from unix: %s"),
+		       _("Error reading from file descriptor: %s"),
 		       g_strerror (errsv));
 	}
-      
+
       break;
     }
 
+  g_cancellable_release_fd (cancellable);
   return res;
 }
 
@@ -436,7 +444,7 @@ g_unix_input_stream_close (GInputStream  *stream,
 
           g_set_error (error, G_IO_ERROR,
                        g_io_error_from_errno (errsv),
-                       _("Error closing unix: %s"),
+                       _("Error closing file descriptor: %s"),
                        g_strerror (errsv));
         }
       break;
@@ -476,12 +484,12 @@ read_async_cb (int            fd,
 	{
           int errsv = errno;
 
-	  if (errsv == EINTR)
+	  if (errsv == EINTR || errsv == EAGAIN)
-	    continue;
+	    return TRUE;
 	  
 	  g_set_error (&error, G_IO_ERROR,
 		       g_io_error_from_errno (errsv),
-		       _("Error reading from unix: %s"),
+		       _("Error reading from file descriptor: %s"),
 		       g_strerror (errsv));
 	}
       break;
@@ -631,7 +639,7 @@ close_async_cb (CloseAsyncData *data)
 
           g_set_error (&error, G_IO_ERROR,
                        g_io_error_from_errno (errsv),
-                       _("Error closing unix: %s"),
+                       _("Error closing file descriptor: %s"),
                        g_strerror (errsv));
         }
       break;

gio/gunixoutputstream.c

@@ -346,56 +346,64 @@ g_unix_output_stream_write (GOutputStream  *stream,
 			    GError        **error)
 {
   GUnixOutputStream *unix_stream;
-  gssize res;
+  gssize res = -1;
   GPollFD poll_fds[2];
+  int nfds;
   int poll_ret;
 
   unix_stream = G_UNIX_OUTPUT_STREAM (stream);
 
+  poll_fds[0].fd = unix_stream->priv->fd;
+  poll_fds[0].events = G_IO_OUT;
+
   if (unix_stream->priv->is_pipe_or_socket &&
       g_cancellable_make_pollfd (cancellable, &poll_fds[1]))
+    nfds = 2;
+  else
+    nfds = 1;
+
+  while (1)
     {
-      poll_fds[0].fd = unix_stream->priv->fd;
+      poll_fds[0].revents = poll_fds[1].revents = 0;
-      poll_fds[0].events = G_IO_OUT;
       do
-	poll_ret = g_poll (poll_fds, 2, -1);
+	poll_ret = g_poll (poll_fds, nfds, -1);
       while (poll_ret == -1 && errno == EINTR);
-      g_cancellable_release_fd (cancellable);
+
-      
       if (poll_ret == -1)
 	{
           int errsv = errno;
 
 	  g_set_error (error, G_IO_ERROR,
 		       g_io_error_from_errno (errsv),
-		       _("Error writing to unix: %s"),
+		       _("Error writing to file descriptor: %s"),
 		       g_strerror (errsv));
-	  return -1;
+	  break;
 	}
-    }
+
-      
-  while (1)
-    {
       if (g_cancellable_set_error_if_cancelled (cancellable, error))
-	return -1;
+	break;
+
+      if (!poll_fds[0].revents)
+	continue;
 
       res = write (unix_stream->priv->fd, buffer, count);
       if (res == -1)
 	{
           int errsv = errno;
 
-	  if (errsv == EINTR)
+	  if (errsv == EINTR || errsv == EAGAIN)
 	    continue;
-	  
+
 	  g_set_error (error, G_IO_ERROR,
 		       g_io_error_from_errno (errsv),
-		       _("Error writing to unix: %s"),
+		       _("Error writing to file descriptor: %s"),
 		       g_strerror (errsv));
 	}
-      
+
       break;
     }
-  
+
+  g_cancellable_release_fd (cancellable);
   return res;
 }
 
@@ -422,7 +430,7 @@ g_unix_output_stream_close (GOutputStream  *stream,
 
 	  g_set_error (error, G_IO_ERROR,
 		       g_io_error_from_errno (errsv),
-		       _("Error closing unix: %s"),
+		       _("Error closing file descriptor: %s"),
 		       g_strerror (errsv));
 	}
       break;
@@ -462,12 +470,12 @@ write_async_cb (int             fd,
 	{
           int errsv = errno;
 
-	  if (errsv == EINTR)
+	  if (errsv == EINTR || errsv == EAGAIN)
-	    continue;
+	    return TRUE;
 	  
 	  g_set_error (&error, G_IO_ERROR,
 		       g_io_error_from_errno (errsv),
-		       _("Error writing to unix: %s"),
+		       _("Error writing to file descriptor: %s"),
 		       g_strerror (errsv));
 	}
       break;
@@ -586,7 +594,7 @@ close_async_cb (CloseAsyncData *data)
 
 	  g_set_error (&error, G_IO_ERROR,
 		       g_io_error_from_errno (errsv),
-		       _("Error closing unix: %s"),
+		       _("Error closing file descriptor: %s"),
 		       g_strerror (errsv));
 	}
       break;

gio/tests/unix-streams.c

@@ -22,6 +22,7 @@
 #include <gio/gio.h>
 #include <gio/gunixinputstream.h>
 #include <gio/gunixoutputstream.h>
+#include <glib/glib-unix.h>
 #include <signal.h>
 #include <stdlib.h>
 #include <string.h>
@@ -194,7 +195,7 @@ timeout (gpointer cancellable)
 }
 
 static void
-test_pipe_io (void)
+test_pipe_io (gconstpointer nonblocking)
 {
   GThread *writer, *reader;
   GInputStream *in;
@@ -212,6 +213,20 @@ test_pipe_io (void)
 
   g_assert (pipe (writer_pipe) == 0 && pipe (reader_pipe) == 0);
 
+  if (nonblocking)
+    {
+      GError *error = NULL;
+
+      g_unix_set_fd_nonblocking (writer_pipe[0], TRUE, &error);
+      g_assert_no_error (error);
+      g_unix_set_fd_nonblocking (writer_pipe[1], TRUE, &error);
+      g_assert_no_error (error);
+      g_unix_set_fd_nonblocking (reader_pipe[0], TRUE, &error);
+      g_assert_no_error (error);
+      g_unix_set_fd_nonblocking (reader_pipe[1], TRUE, &error);
+      g_assert_no_error (error);
+    }
+
   writer_cancel = g_cancellable_new ();
   reader_cancel = g_cancellable_new ();
   main_cancel = g_cancellable_new ();
@@ -249,7 +264,12 @@ main (int   argc,
   g_type_init ();
   g_test_init (&argc, &argv, NULL);
 
-  g_test_add_func ("/unix-streams/pipe-io-test", test_pipe_io);
+  g_test_add_data_func ("/unix-streams/pipe-io-test",
+			GINT_TO_POINTER (FALSE),
+			test_pipe_io);
+  g_test_add_data_func ("/unix-streams/nonblocking-io-test",
+			GINT_TO_POINTER (TRUE),
+			test_pipe_io);
 
   return g_test_run();
 }