Modernize the example echo module and fix some style(9) issues in the
code. Reviewed by: alfred (code) Reviewed by: gonzo (code) Reviewed by: ehaupt (code) Approved by: bcr (mentor)
This commit is contained in:
Eitan Adler
parent
2a7976d2a9
commit
ac36ffe323
Notes:
svn2git
2020-12-08 03:00:23 +00:00
svn path=/head/; revision=40167
1 changed files with 62 additions and 47 deletions
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@ -48,13 +48,7 @@
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<para>Most devices in a &unix;-like operating system are accessed
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through device-nodes, sometimes also called special files.
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These files are usually located under the directory
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<filename>/dev</filename> in the filesystem hierarchy.
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In releases of FreeBSD older than 5.0-RELEASE, where
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&man.devfs.5; support is not integrated into FreeBSD,
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each device node must be
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created statically and independent of the existence of the
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associated device driver. Most device nodes on the system are
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created by running <command>MAKEDEV</command>.</para>
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<filename>/dev</filename> in the filesystem hierarchy.</para>
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<para>Device drivers can roughly be broken down into two
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categories; character and network device drivers.</para>
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@ -212,20 +206,19 @@ KMOD=skeleton
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<example>
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<title>Example of a Sample Echo Pseudo-Device Driver for
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&os; 5.X</title>
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&os; 10.X</title>
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<programlisting>/*
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* Simple `echo' pseudo-device KLD
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* Simple Echo pseudo-device KLD
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*
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* Murray Stokely
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*
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* Converted to 5.X by Søren (Xride) Straarup
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* Søren (Xride) Straarup
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* Eitan Adler
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*/
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#include <sys/types.h>
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#include <sys/module.h>
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#include <sys/systm.h> /* uprintf */
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#include <sys/errno.h>
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#include <sys/param.h> /* defines used in kernel.h */
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#include <sys/kernel.h> /* types used in module initialization */
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#include <sys/conf.h> /* cdevsw struct */
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@ -234,7 +227,6 @@ KMOD=skeleton
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#define BUFFERSIZE 256
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/* Function prototypes */
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static d_open_t echo_open;
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static d_close_t echo_close;
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@ -251,15 +243,14 @@ static struct cdevsw echo_cdevsw = {
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.d_name = "echo",
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};
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typedef struct s_echo {
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struct s_echo {
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char msg[BUFFERSIZE];
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int len;
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} t_echo;
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};
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/* vars */
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static struct cdev *echo_dev;
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static int count;
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static t_echo *echomsg;
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static struct s_echo *echomsg;
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MALLOC_DECLARE(M_ECHOBUF);
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MALLOC_DEFINE(M_ECHOBUF, "echobuffer", "buffer for echo module");
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@ -270,20 +261,25 @@ MALLOC_DEFINE(M_ECHOBUF, "echobuffer", "buffer for echo module");
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*/
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static int
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echo_loader(struct module *m, int what, void *arg)
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echo_loader(struct module *m __unused, int what, void *arg __unused)
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{
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int err = 0;
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int error = 0;
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switch (what) {
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case MOD_LOAD: /* kldload */
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echo_dev = make_dev(<literal>&</literal>echo_cdevsw,
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error = make_dev_p(MAKEDEV_CHECKNAME | MAKEDEV_WAITOK,
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&echo_dev,
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&echo_cdevsw,
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0,
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UID_ROOT,
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GID_WHEEL,
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0600,
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"echo");
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if (error != 0)
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break;
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/* kmalloc memory for use by this driver */
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echomsg = malloc(sizeof(t_echo), M_ECHOBUF, M_WAITOK);
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echomsg = malloc(sizeof(*echomsg), M_ECHOBUF, M_WAITOK);
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printf("Echo device loaded.\n");
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break;
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case MOD_UNLOAD:
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@ -292,26 +288,27 @@ echo_loader(struct module *m, int what, void *arg)
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printf("Echo device unloaded.\n");
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break;
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default:
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err = EOPNOTSUPP;
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error = EOPNOTSUPP;
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break;
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}
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return(err);
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return (error);
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}
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static int
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echo_open(struct cdev *dev, int oflags, int devtype, struct thread *p)
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echo_open(struct cdev *dev __unused, int oflags __unused, int devtype __unused, struct thread *p __unused)
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{
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int err = 0;
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int error = 0;
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uprintf("Opened device \"echo\" successfully.\n");
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return(err);
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return (error);
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}
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static int
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echo_close(struct cdev *dev, int fflag, int devtype, struct thread *p)
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echo_close(struct cdev *dev __unused, int fflag __unused, int devtype __unused, struct thread *p __unused)
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{
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uprintf("Closing device \"echo.\"\n");
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return(0);
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return (0);
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}
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/*
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@ -321,21 +318,21 @@ echo_close(struct cdev *dev, int fflag, int devtype, struct thread *p)
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*/
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static int
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echo_read(struct cdev *dev, struct uio *uio, int ioflag)
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echo_read(struct cdev *dev __unused, struct uio *uio, int ioflag __unused)
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{
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int err = 0;
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int amt;
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int error, amt;
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/*
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* How big is this read operation? Either as big as the user wants,
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* or as big as the remaining data
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*/
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amt = MIN(uio->uio_resid, (echomsg->len - uio->uio_offset > 0) ?
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echomsg->len - uio->uio_offset : 0);
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if ((err = uiomove(echomsg->msg + uio->uio_offset, amt, uio)) != 0) {
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amt = MIN(uio-<uio_resid, echomsg-<len - uio-<uio_offset);
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uio-<uio_offset += amt;
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if ((error = uiomove(echomsg-<msg, amt, uio)) != 0)
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uprintf("uiomove failed!\n");
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}
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return(err);
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return (error);
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}
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/*
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@ -344,23 +341,39 @@ echo_read(struct cdev *dev, struct uio *uio, int ioflag)
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*/
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static int
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echo_write(struct cdev *dev, struct uio *uio, int ioflag)
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echo_write(struct cdev *dev __unused, struct uio *uio, int ioflag __unused)
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{
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int err = 0;
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int error, amt;
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/* Copy the string in from user memory to kernel memory */
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err = copyin(uio->uio_iov->iov_base, echomsg->msg,
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MIN(uio->uio_iov->iov_len, BUFFERSIZE - 1));
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if (uio-<uio_offset != 0 && (uio-<uio_offset != echomsg-<len))
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return (EINVAL);
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/*
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* This is new message, reset length
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*/
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if (uio-<uio_offset == 0)
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echomsg-<len = 0;
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/* NULL charcter should be overriden */
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if (echomsg-<len != 0)
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echomsg-<len--;
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/* Copy the string in from user memory to kernel memory */
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amt = MIN(uio-<uio_resid, (BUFFERSIZE - echomsg-<len));
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error = uiomove(echomsg-<msg + uio-<uio_offset, amt, uio);
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/* Now we need to null terminate, then record the length */
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*(echomsg->msg + MIN(uio->uio_iov->iov_len, BUFFERSIZE - 1)) = 0;
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echomsg->len = MIN(uio->uio_iov->iov_len, BUFFERSIZE);
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echomsg-<len += amt + 1;
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uio-<uio_offset += amt + 1;
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echomsg-<msg[echomsg-<len - 1] = 0;
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//echomsg-<msg[BUFFERSIZE - 1] = '\n';
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if (err != 0) {
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if (error != 0)
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uprintf("Write failed: bad address!\n");
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}
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count++;
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return(err);
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return (error);
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}
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DEV_MODULE(echo,echo_loader,NULL);</programlisting>
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@ -371,7 +384,9 @@ DEV_MODULE(echo,echo_loader,NULL);</programlisting>
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<screen>&prompt.root; <userinput>echo -n "Test Data" > /dev/echo</userinput>
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&prompt.root; <userinput>cat /dev/echo</userinput>
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Test Data</screen>
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Opened device "echo" successfully.
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Test Data
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Closing device "echo."</screen>
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<para>Real hardware devices are described in the next chapter.</para>
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