[PATCH] mdadm: monitor event argument passing

[PATCH] mdadm: monitor event argument passing

[Paul Clements]

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I've been looking at the mdadm monitor, and thought it might be useful 
if it allowed extra context information (in the form of command line 
arguments) to be sent to the event program, so instead of just:

# mdadm -F /dev/md0 -p "md_event"

you could do something like:

# mdadm -F /dev/md0 -p "md_event -i <some_info>"

And the "-i <some_info>" will be passed on the command line to the event 
program. Of course you can usually figure out what the extra context 
should be in the event program itself, but it may take more work.

Here's a short patch (against mdadm 2.4) that does this.

Thanks,
Paul

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Signed-Off-By: Paul Clements <paul.clements@steeleye.com>

 Monitor.c |   23 ++++++++++++++++++++++-
 1 files changed, 22 insertions(+), 1 deletion(-)
--- mdadm-2.4/Monitor.c	2006-03-28 17:59:42.000000000 -0500
+++ mdadm-2.4-event-args/Monitor.c	2006-03-31 13:19:40.000000000 -0500
@@ -464,6 +464,27 @@ static void alert(char *event, char *dev
 		  int dosyslog)
 {
 	int priority;
+	int cnt = 0;
+	char path[PATH_MAX];
+	char *space, *ptr;
+	char *args[256];
+
+	if (cmd) {
+		strcpy(path, cmd);
+		ptr = path;
+		do {
+			space = strchr(ptr, ' ');
+			if (!space)
+				break;
+			args[cnt++] = ptr;
+			*space = 0;
+			ptr = space+1;
+		} while (1);
+		args[cnt++] = ptr;
+		args[cnt++] = event;
+		args[cnt++] = dev;
+		args[cnt++] = disc;
+	}
 
 	if (!cmd && !mailaddr) {
 		time_t now = time(0);
@@ -479,7 +500,7 @@ static void alert(char *event, char *dev
 		case -1:
 			break;
 		case 0:
-			execl(cmd, cmd, event, dev, disc, NULL);
+			execv(path, args); //execl(cmd,  cmd, event, dev, disc, NULL);
 			exit(2);
 		}
 	}

Re: [PATCH] mdadm: monitor event argument passing

[Neil Brown]

On Friday March 31, paul.clements@steeleye.com wrote:
> 
> I've been looking at the mdadm monitor, and thought it might be useful 
> if it allowed extra context information (in the form of command line 
> arguments) to be sent to the event program, so instead of just:
> 
> # mdadm -F /dev/md0 -p "md_event"
> 
> you could do something like:
> 
> # mdadm -F /dev/md0 -p "md_event -i <some_info>"
> 
> And the "-i <some_info>" will be passed on the command line to the event 
> program. Of course you can usually figure out what the extra context 
> should be in the event program itself, but it may take more work.

I would recommend the use of environment variables for this:

  md_event_context=<some_info> mdadm -F /dev/md0 -p md_event

It is true that this cannot be specified in mdadm.conf, but I don't
think you really need it at all in that context.  The <some_info> can
be explicit in the script rather than in mdadm.conf.

Does that work for you?

NeilBrown

Re: [PATCH] mdadm: monitor event argument passing

[Paul Clements]

Neil Brown wrote:
> On Friday March 31, paul.clements@steeleye.com wrote:
> 
>>I've been looking at the mdadm monitor, and thought it might be useful 
>>if it allowed extra context information (in the form of command line 
>>arguments) to be sent to the event program, so instead of just:
>>
>># mdadm -F /dev/md0 -p "md_event"
>>
>>you could do something like:
>>
>># mdadm -F /dev/md0 -p "md_event -i <some_info>"
>>
>>And the "-i <some_info>" will be passed on the command line to the event 
>>program. Of course you can usually figure out what the extra context 
>>should be in the event program itself, but it may take more work.
> 
> 
> I would recommend the use of environment variables for this:
> 
>   md_event_context=<some_info> mdadm -F /dev/md0 -p md_event

> Does that work for you?

Yes, that would work.

Thanks,
Paul