[PATCH 1/3] Make xenstored manage its own pidfile

[PATCH 1/3] Make xenstored manage its own pidfile

[Anthony Liguori]

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The following patch makes xenstored manage its own pidfile which makes 
it impossible for it to be started multiple times.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com

Regards,

Anthony Liguori

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diff -r 1d240086de52 tools/xenstore/utils.c
--- a/tools/xenstore/utils.c	Thu Aug  4 15:02:09 2005
+++ b/tools/xenstore/utils.c	Thu Aug  4 10:54:13 2005
@@ -84,6 +84,9 @@
 void daemonize(void)
 {
 	pid_t pid;
+	int fd;
+	size_t len;
+	char buf[100];
 
 	/* Separate from our parent via fork, so init inherits us. */
 	if ((pid = fork()) < 0)
@@ -101,6 +104,18 @@
 	chdir("/");
 	/* Discard our parent's old-fashioned umask prejudices. */
 	umask(0);
+
+	fd = open("/var/run/xenstored.pid", O_RDWR | O_CREAT);
+	if (fd == -1) {
+		exit(1);
+	}
+
+	if (lockf(fd, F_TLOCK, 0) == -1) {
+		exit(1);
+	}
+
+	len = sprintf(buf, "%d\n", getpid());
+	write(fd, buf, len);
 }
 
 

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Re: [PATCH 1/3] Make xenstored manage its own pidfile

[Muli Ben-Yehuda]

On Thu, Aug 04, 2005 at 11:03:11AM -0500, Anthony Liguori wrote:

> The following patch makes xenstored manage its own pidfile which makes 
> it impossible for it to be started multiple times.
> 
> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com
> 
> Regards,
> 
> Anthony Liguori

> diff -r 1d240086de52 tools/xenstore/utils.c
> --- a/tools/xenstore/utils.c	Thu Aug  4 15:02:09 2005
> +++ b/tools/xenstore/utils.c	Thu Aug  4 10:54:13 2005
> @@ -84,6 +84,9 @@
>  void daemonize(void)
>  {
>  	pid_t pid;
> +	int fd;
> +	size_t len;
> +	char buf[100];
>  
>  	/* Separate from our parent via fork, so init inherits us. */
>  	if ((pid = fork()) < 0)
> @@ -101,6 +104,18 @@
>  	chdir("/");
>  	/* Discard our parent's old-fashioned umask prejudices. */
>  	umask(0);
> +
> +	fd = open("/var/run/xenstored.pid", O_RDWR | O_CREAT);
> +	if (fd == -1) {
> +		exit(1);

How about exit(errno), with or without a descriptive message?

> +	}
> +
> +	if (lockf(fd, F_TLOCK, 0) == -1) {
> +		exit(1);

Likewise?

> +
> +	len = sprintf(buf, "%d\n", getpid());
> +	write(fd, buf, len);

Check returen value from write?

Cheers,
Muli
-- 
Muli Ben-Yehuda
http://www.mulix.org | http://mulix.livejournal.com/