X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=stdin.c;h=20b9250e9b7fbf3c252e20dff8891bfeeb5112dd;hp=b25a0ba013fb03b19cb757d07ff483c9389a0d70;hb=761d9bd95a6601c0b3be6591a6b6672b755e1fbe;hpb=2f07d34b5d4c37606be5849b6ee51e0443707898

diff --git a/stdin.c b/stdin.c
index b25a0ba0..20b9250e 100644
--- a/stdin.c
+++ b/stdin.c
@@ -69,6 +69,12 @@ static int stdin_post_select(struct sched *s, struct task *t)
 	sz = btr_pool_get_buffer(sit->btrp, &buf);
 	if (sz == 0)
 		return 0;
+	if (sit->must_set_nonblock_flag) {
+		ret = mark_fd_nonblocking(STDIN_FILENO);
+		if (ret < 0)
+			goto err;
+		sit->must_set_nonblock_flag = false;
+	}
 	/*
 	 * Do not use the maximal size to avoid having only a single buffer
 	 * reference for the whole pool. This is bad because if that single
@@ -82,6 +88,8 @@ static int stdin_post_select(struct sched *s, struct task *t)
 		return 0;
 err:
 	btr_remove_node(&sit->btrn);
+	/* Revert to blocking mode if necessary. */
+	fcntl(STDIN_FILENO, F_SETFL, sit->fd_flags);
 	//btr_pool_free(sit->btrp);
 	return ret;
 }
@@ -92,8 +100,7 @@ err:
  * \param sit The stdin task structure.
  *
  * This fills in the pre/post select function pointers of the task structure
- * given by \a sit. Moreover, the stdin file desctiptor is set to nonblocking
- * mode, and a buffer tree is created.
+ * given by \a sit and creates a buffer tree for I/O.
  */
 void stdin_set_defaults(struct stdin_task *sit)
 {
@@ -103,9 +110,18 @@ void stdin_set_defaults(struct stdin_task *sit)
 	sit->task.post_select = stdin_post_select;
 	sit->btrp = btr_pool_new("stdin", 128 * 1024);
 	sprintf(sit->task.status, "stdin reader");
-	ret = mark_fd_nonblocking(STDIN_FILENO);
-	if (ret >= 0)
-		return;
-	PARA_EMERG_LOG("%s\n", para_strerror(-ret));
-	exit(EXIT_FAILURE);
+	/*
+	 * Both STDIN_FILENO and STDOUT_FILENO may refer to the same open file
+	 * description (the terminal), and thus share the same file status
+	 * flags. In order to not interfere with the stdout task, we only get
+	 * the file status flags for STDIN here and save a copy. The nonblock
+	 * flag is set later on the first read.
+	 */
+	ret = fcntl(STDIN_FILENO, F_GETFL);
+	if (ret < 0) {
+		PARA_EMERG_LOG("F_GETFL: %s\n", strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+	sit->fd_flags = ret;
+	sit->must_set_nonblock_flag = (sit->fd_flags & O_NONBLOCK) == 0;
 }