[tarantool-patches] [PATCH v2] Fix O_NONBLOCK flag loss

[tarantool-patches] [PATCH v2] Fix O_NONBLOCK flag loss

[Olga Arkhangelskaia]

During syslog reconnect we lose nonblock flag. This leads to misbehavior
while logging. Tarantool hangs forever. Test for this fix will be available
in 1.10.

Closes #3615
---
https://github.com/tarantool/tarantool/issues/3615
https://github.com/tarantool/tarantool/tree/OKriw/gh-3615-loss-nonblock-1.9

v1:
https://www.freelists.org/post/tarantool-patches/PATCH-Fix-O-NONBLOCK-flag-loss

Changes in v2:
-rebased on 1.9
-changed set_nonblock arg
-set flag in one more place

 src/say.c | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/src/say.c b/src/say.c
index 063e0295c..9c1066efc 100644
--- a/src/say.c
+++ b/src/say.c
@@ -238,6 +238,23 @@ write_to_file(struct log *log, int total);
 static void
 write_to_syslog(struct log *log, int total);
 
+/**
+ * Sets O_NONBLOCK flag in case if lognonblock is set.
+ */
+static void
+set_nonblock(struct log *log)
+{
+	if (!log->nonblock)
+		return;
+	else {
+		int flags;
+		if ((flags = fcntl(log->fd, F_GETFL, 0)) < 0 ||
+				fcntl(log->fd, F_SETFL, flags | O_NONBLOCK) < 0) {
+			say_syserror("fcntl, fd=%i", log->fd);
+		}
+	}
+}
+
 /**
  * Rotate logs on SIGHUP
  */
@@ -262,13 +279,8 @@ log_rotate(struct log *log)
 	dup2(fd, log->fd);
 	close(fd);
 
-	if (log->nonblock) {
-		int flags;
-		if ( (flags = fcntl(log->fd, F_GETFL, 0)) < 0 ||
-		     fcntl(log->fd, F_SETFL, flags | O_NONBLOCK) < 0) {
-			say_syserror("fcntl, fd=%i", log->fd);
-		}
-	}
+	set_nonblock(log);
+
 	/* We are in ev signal handler
 	 * so we don't have to be worry about async signal safety
 	 */
@@ -567,12 +579,7 @@ log_create(struct log *log, const char *init_str, bool nonblock)
 		 * non-blocking: this will garble interactive
 		 * console output.
 		 */
-		if (log->nonblock) {
-			int flags;
-			if ( (flags = fcntl(log->fd, F_GETFL, 0)) < 0 ||
-			     fcntl(log->fd, F_SETFL, flags | O_NONBLOCK) < 0)
-				say_syserror("fcntl, fd=%i", log->fd);
-		}
+		set_nonblock(log);
 	} else {
 		log->type = SAY_LOGGER_STDERR;
 		log->fd = STDERR_FILENO;
@@ -940,6 +947,7 @@ write_to_syslog(struct log *log, int total)
 			close(log->fd);
 		log->fd = log_syslog_connect(log);
 		if (log->fd >= 0) {
+			set_nonblock(log);
 			/*
 			 * In a case or error the log message is
 			 * lost. We can not wait for connection -
-- 
2.14.3 (Apple Git-98)

Re: [tarantool-patches] [PATCH v2] Fix O_NONBLOCK flag loss

[Vladimir Davydov]

Please prefix the subject line with a subsystem name ("say: " in your
case).

On Mon, Aug 13, 2018 at 09:37:58AM +0300, Olga Arkhangelskaia wrote:
> During syslog reconnect we lose nonblock flag. This leads to misbehavior
> while logging. Tarantool hangs forever.

> Test for this fix will be available in 1.10.

Please explain why (in the commit message).

> 
> Closes #3615
> ---
> https://github.com/tarantool/tarantool/issues/3615
> https://github.com/tarantool/tarantool/tree/OKriw/gh-3615-loss-nonblock-1.9
> 
> v1:
> https://www.freelists.org/post/tarantool-patches/PATCH-Fix-O-NONBLOCK-flag-loss
> 
> Changes in v2:
> -rebased on 1.9
> -changed set_nonblock arg
> -set flag in one more place
> 
>  src/say.c | 34 +++++++++++++++++++++-------------
>  1 file changed, 21 insertions(+), 13 deletions(-)
> 
> diff --git a/src/say.c b/src/say.c
> index 063e0295c..9c1066efc 100644
> --- a/src/say.c
> +++ b/src/say.c
> @@ -238,6 +238,23 @@ write_to_file(struct log *log, int total);
>  static void
>  write_to_syslog(struct log *log, int total);
>  
> +/**
> + * Sets O_NONBLOCK flag in case if lognonblock is set.
> + */
> +static void
> +set_nonblock(struct log *log)

Please prefix this function with 'log_' (log_set_nonblock), because this
function is a method of 'log' object.

> +{
> +	if (!log->nonblock)
> +		return;
> +	else {

'else' is pointless.

> +		int flags;
> +		if ((flags = fcntl(log->fd, F_GETFL, 0)) < 0 ||
> +				fcntl(log->fd, F_SETFL, flags | O_NONBLOCK) < 0) {

Malformed indentation. Please align the next line to 'if (', as we do
everywhere else.

> +			say_syserror("fcntl, fd=%i", log->fd);
> +		}
> +	}
> +}