X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=stdin.c;h=20b9250e9b7fbf3c252e20dff8891bfeeb5112dd;hp=fd803ae5441acf01446dadab89c35d3bec14cecd;hb=fb4022dfafa1d6f86f741767ecaed8e41c53352a;hpb=c5e38315901ea63efd169af5d4ba3f3c66db7de9

diff --git a/stdin.c b/stdin.c
index fd803ae5..20b9250e 100644
--- a/stdin.c
+++ b/stdin.c
@@ -33,7 +33,6 @@ static void stdin_pre_select(struct sched *s, struct task *t)
 	struct stdin_task *sit = container_of(t, struct stdin_task, task);
 	int ret;
 
-	t->error = 0;
 	ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
 	if (ret < 0)
 		sched_min_delay(s);
@@ -55,22 +54,27 @@ static void stdin_pre_select(struct sched *s, struct task *t)
  * appears to be readable, data is read from stdin and fed into the buffer
  * tree.
  */
-static void stdin_post_select(struct sched *s, struct task *t)
+static int stdin_post_select(struct sched *s, struct task *t)
 {
 	struct stdin_task *sit = container_of(t, struct stdin_task, task);
 	ssize_t ret;
 	size_t sz, n;
 	char *buf = NULL;
 
-	t->error = 0;
 	ret = btr_node_status(sit->btrn, 0, BTR_NT_ROOT);
 	if (ret < 0)
 		goto err;
 	if (ret == 0)
-		return;
+		return 0;
 	sz = btr_pool_get_buffer(sit->btrp, &buf);
 	if (sz == 0)
-		return;
+		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
@@ -81,11 +85,13 @@ static void stdin_post_select(struct sched *s, struct task *t)
 	if (n > 0)
 		btr_add_output_pool(sit->btrp, n, sit->btrn);
 	if (ret >= 0)
-		return;
+		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);
-	t->error = ret;
+	return ret;
 }
 
 /**
@@ -94,8 +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)
 {
@@ -105,9 +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;
 }