[PATCH 2/2] io: report a warning when a file channel is created from a stdio fd

[Filip Hejsek <filip.hejsek@gmail.com>]

A channel closes its fd when the last reference to it is dropped.
Closing stdio fds is typically unwanted, so warn when they are passed to
qio_channel_file_new_fd().

Signed-off-by: Filip Hejsek <filip.hejsek@gmail.com>
---
 io/channel-file.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/io/channel-file.c b/io/channel-file.c
index 5cef75a67c..98ed8a973e 100644
--- a/io/channel-file.c
+++ b/io/channel-file.c
@@ -19,6 +19,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/error-report.h"
 #include "io/channel-file.h"
 #include "io/channel-util.h"
 #include "io/channel-watch.h"
@@ -32,6 +33,11 @@ qio_channel_file_new_fd(int fd)
 {
     QIOChannelFile *ioc;
 
+    if (fd <= STDERR_FILENO) {
+        warn_report("potential bug: creating a channel from stdio fd %d; "
+                    "the fd will be closed when the channel is destroyed", fd);
+    }
+
     ioc = QIO_CHANNEL_FILE(object_new(TYPE_QIO_CHANNEL_FILE));
 
     ioc->fd = fd;

-- 
2.56.0