bin/125680: atacontrol(8): atacontrol depends on executable in /usr

[Antoine Brodin]

On Mon, Jul 21, 2008 at 10:04 AM, Garrett Cooper <yanefbsd at gmail.com> wrote:
> Antoine,
>     You're right. I flip-flopped parent and child there in my
> original statement.
>     I also saw the async ('&') terminal command.
>     But what is ultimately gained by forking another process to read
> a device other than just resuming control for the terminal to the
> user? It seems like all this does is create potential for additional
> zombie processes on the system...
>     Just as an experiment, could you insert another printf or some
> statement to ensure that the read is deterministically completed every
> time?

I have attached a patch with an extra printf.
I guess that the dd/read is done in the background because it can take
hours, so the user doesn't have to wait hours to have his terminal
back.

Cheers,

Antoine
-------------- next part --------------
Index: sbin/atacontrol/atacontrol.c
===================================================================
RCS file: /home/ncvs/src/sbin/atacontrol/atacontrol.c,v
retrieving revision 1.48
diff -u -p -r1.48 atacontrol.c
--- sbin/atacontrol/atacontrol.c	15 May 2008 01:25:29 -0000	1.48
+++ sbin/atacontrol/atacontrol.c	21 Jul 2008 08:19:46 -0000
@@ -37,6 +37,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sysexits.h>
+#include <unistd.h>
 
 static const char *
 mode2str(int mode)
@@ -517,12 +518,31 @@ main(int argc, char **argv)
 		if (ioctl(fd, IOCATARAIDREBUILD, &array) < 0)
 			warn("ioctl(IOCATARAIDREBUILD)");
 		else {
-			char buffer[128];
-			sprintf(buffer, "/usr/bin/nice -n 20 /bin/dd "
-				"if=/dev/ar%d of=/dev/null bs=1m &",
-				array);
-			if (system(buffer))
-				warn("background dd");
+			char device[64];
+			char *buffer;
+			int arfd;
+
+			switch (fork()) {
+			case -1:
+				err(1, "fork");
+			case 0:
+				nice(20);
+				snprintf(device, sizeof(device), "/dev/ar%d",
+					array);
+				if ((arfd = open(device, O_RDONLY)) == -1)
+					err(1, "open %s", device);
+				if ((buffer = malloc(1024 * 1024)) == NULL)
+					err(1, "malloc");
+				while (read(arfd, buffer, 1024 * 1024) > 0)
+					;
+				printf("atacontrol: ar%d rebuild completed\n",
+					array);
+				free(buffer);
+				close(arfd);
+				break;
+			default:
+				break;
+			}
 		}
 		exit(EX_OK);
 	}