Fix for the broken I/O watch conditions on child exit under OSX

Under OSX, after child death, the read watches receive input
conditions instead of error conditions, so we convert the termination
statuses (ERROR and EOF) into their respective conditions. Should not
hurt the other OS.

src/spawn.c

@@ -665,13 +665,14 @@ static gboolean spawn_read_cb(GIOChannel *channel, GIOCondition condition, gpoin
 	if (condition & (G_IO_IN | G_IO_PRI))
 	{
 		gsize chars_read;
+		GIOStatus status;
 
 		if (line_buffer)
 		{
 			gsize n = line_buffer->len;
 
-			while ((g_io_channel_read_chars(channel, line_buffer->str + n,
-				DEFAULT_IO_LENGTH, &chars_read, NULL) == G_IO_STATUS_NORMAL))
+			while ((status = g_io_channel_read_chars(channel, line_buffer->str + n,
+				DEFAULT_IO_LENGTH, &chars_read, NULL)) == G_IO_STATUS_NORMAL)
 			{
 				g_string_set_size(line_buffer, n + chars_read);
 
@@ -706,8 +707,8 @@ static gboolean spawn_read_cb(GIOChannel *channel, GIOCondition condition, gpoin
 		}
 		else
 		{
-			while (g_io_channel_read_chars(channel, buffer->str, sc->max_length,
-				&chars_read, NULL) == G_IO_STATUS_NORMAL)
+			while ((status = g_io_channel_read_chars(channel, buffer->str, sc->max_length,
+				&chars_read, NULL)) == G_IO_STATUS_NORMAL)
 			{
 				g_string_set_size(buffer, chars_read);
 				/* data only, failures are reported separately below */
@@ -717,6 +718,14 @@ static gboolean spawn_read_cb(GIOChannel *channel, GIOCondition condition, gpoin
 					break;
 			}
 		}
+
+		/* Under OSX, after child death, the read watches receive input conditions instead
+		   of error conditions, so we convert the termination statuses into conditions.
+		   Should not hurt the other OS. */
+		if (status == G_IO_STATUS_ERROR)
+			failure |= G_IO_ERR;
+		else if (status == G_IO_STATUS_EOF)
+			failure |= G_IO_HUP;
 	}
 
 	if (failure)  /* we must signal the callback */
@@ -734,7 +743,7 @@ static gboolean spawn_read_cb(GIOChannel *channel, GIOCondition condition, gpoin
 			g_string_truncate(buffer, 0);
 		}
 
-		sc->cb.read(buffer, condition, sc->cb_data);
+		sc->cb.read(buffer, condition | failure, sc->cb_data);
 	}
 
 	if (buffer != sc->buffer)