random

commit 18693b9b2654b84d0913df54ed27c57510120f9f
parent 159798155e8ac5a3543bd29aed523ba0f2b4b831
Author: Christos Margiolis <christos@margiolis.net>
Date:   Mon,  6 Mar 2023 16:37:20 +0200

improve mydev

Diffstat:
M
mydev_freebsd/mydev.c
 | 
72
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------------
M
mydev_freebsd/mydev.h
 | 
9
+++++----
M
mydev_freebsd/mydev_test.c
 | 
42
+++++++++++++++++++++++++-----------------

3 files changed, 87 insertions(+), 36 deletions(-)
diff --git a/mydev_freebsd/mydev.c b/mydev_freebsd/mydev.c
@@ -1,12 +1,24 @@
+#include <sys/types.h>
 #include <sys/param.h>
 #include <sys/conf.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
 #include <sys/module.h>
+#include <sys/malloc.h>
 #include <sys/uio.h>
 
 #include "mydev.h"
 
+#define BUFSIZE (1 << 16)
+
+MALLOC_DECLARE(M_MYDEV);
+MALLOC_DEFINE(M_MYDEV, "mydev", "test device");
+
+typedef struct {
+	char	buf[BUFSIZE + 1];
+	size_t	len;
+} foo_t;
+
 static d_open_t		mydev_open;
 static d_close_t	mydev_close;
 static d_read_t		mydev_read;
@@ -26,6 +38,7 @@ static struct cdevsw mydev_cdevsw = {
 };
 
 static struct cdev *mydev_cdev;
+static foo_t *foo;
 
 static int
 mydev_open(struct cdev *dev, int flags, int devtype, struct thread *td)
@@ -46,11 +59,23 @@ mydev_close(struct cdev *dev, int flags, int devtype, struct thread *td)
 static int
 mydev_read(struct cdev *dev, struct uio *uio, int ioflag)
 {
-	char buf[32];
-	int error = 0;
+	size_t amnt;
+	int v, error = 0;
+
+	/*
+	 * Determine how many bytes we have to read. We'll either read the
+	 * remaining bytes (uio->uio_resid) or the number of bytes requested by
+	 * the caller.
+	 */
+	v = uio->uio_offset >= foo->len + 1 ? 0 : foo->len + 1 - uio->uio_offset;
+	amnt = MIN(uio->uio_resid, v);
 
-	strlcpy(buf, "reading from mydev", sizeof(buf));
-	error = uiomove(buf, sizeof(buf), uio);
+	/* Move the bytes from foo->buf to uio. */
+	if ((error = uiomove(foo->buf, amnt, uio)) != 0)
+		uprintf("uiomove failed\n");
+
+	if (!foo->len)
+		uprintf("nothing to read\n");
 
 	return (error);
 }
@@ -58,9 +83,23 @@ mydev_read(struct cdev *dev, struct uio *uio, int ioflag)
 static int
 mydev_write(struct cdev *dev, struct uio *uio, int ioflag)
 {
+	size_t amnt;
 	int error = 0;
 
-	uprintf("mydev: %s\n", (char *)uio->uio_iov->iov_base);
+	/* Do not allow random access. */
+	if (uio->uio_offset != 0 && (uio->uio_offset != foo->len))
+		return (EINVAL);
+
+	/* We're not appending, reset length. */
+	else if (uio->uio_offset == 0)
+		foo->len = 0;
+
+	amnt = MIN(uio->uio_resid, (BUFSIZE - foo->len));
+	if ((error = uiomove(foo->buf + uio->uio_offset, amnt, uio)) != 0)
+		uprintf("uiomove failed");
+
+	foo->len = uio->uio_offset;
+	foo->buf[foo->len] = '\0';
 
 	return (error);
 }
@@ -69,24 +108,23 @@ static int
 mydev_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
     struct thread *td)
 {
-	foo_t *fp;
+	bar_t *bp;
 	int error = 0;
 
 	switch (cmd) {
 	case MYDEVIOC_READ:
-		fp = (foo_t *)addr;
-		fp->x = 10;
-		fp->y = 20;
+		bp = (bar_t *)addr;
+		bp->x = 100;
+		bp->y = 300;
 		break;
 	case MYDEVIOC_WRITE:
-		fp = (foo_t *)addr;
-		uprintf("mydev: x=%d, y=%d\n", fp->x, fp->y);
+		bp = (bar_t *)addr;
+		uprintf("/dev/mydev: x=%d, y=%d\n", bp->x, bp->y);
 		break;
 	case MYDEVIOC_RDWR:
-		fp = (foo_t *)addr;
-		uprintf("mydev: received: x=%d, y=%d\n", fp->x, fp->y);
-		fp->x += 5;
-		fp->y += 5;
+		bp = (bar_t *)addr;
+		bp->x += 15;
+		bp->y += 30;
 		break;
 	default:
 		error = ENOTTY;
@@ -105,9 +143,13 @@ mydev_modevent(module_t mod, int type, void *arg)
 	case MOD_LOAD:
 		mydev_cdev = make_dev(&mydev_cdevsw, 0, UID_ROOT, GID_WHEEL,
 		    0666, "mydev");
+		foo = malloc(sizeof(foo_t), M_MYDEV, M_WAITOK | M_ZERO);
+		foo->buf[0] = '\0';
+		foo->len = 0;
 		break;
 	case MOD_UNLOAD: /* FALLTHROUGH */
 	case MOD_SHUTDOWN:
+		free(foo, M_MYDEV);
 		destroy_dev(mydev_cdev);
 		break;
 	default:
diff --git a/mydev_freebsd/mydev.h b/mydev_freebsd/mydev.h
@@ -1,15 +1,16 @@
 #ifndef _MYDEV_H_
 #define _MYDEV_H_
 
+#include <sys/types.h>
 #include <sys/ioccom.h>
 
 typedef struct {
 	int x;
 	int y;
-} foo_t;
+} bar_t;
 
-#define MYDEVIOC_READ	_IOR('a', 1, foo_t)
-#define MYDEVIOC_WRITE	_IOW('a', 2, foo_t)
-#define MYDEVIOC_RDWR	_IOWR('a', 3, foo_t)
+#define MYDEVIOC_READ	_IOR('a', 1, bar_t)
+#define MYDEVIOC_WRITE	_IOW('a', 2, bar_t)
+#define MYDEVIOC_RDWR	_IOWR('a', 3, bar_t)
 
 #endif /* _MYDEV_H_ */
diff --git a/mydev_freebsd/mydev_test.c b/mydev_freebsd/mydev_test.c
@@ -10,35 +10,43 @@
 int
 main(int argc, char *argv[])
 {
-	foo_t foo;
-	char buf[32];
-	int dev;
+	bar_t bar;
+	char buf[BUFSIZ];
+	int fd;
 
-	if ((dev = open("/dev/mydev", O_RDWR)) < 0)
+	if ((fd = open("/dev/mydev", O_RDWR)) < 0)
 		err(1, "open(/dev/mydev)");
 
-	if (ioctl(dev, MYDEVIOC_READ, &foo) != 0)
+	if (ioctl(fd, MYDEVIOC_READ, &bar) != 0)
 		err(1, "ioctl(MYDEVIOC_READ)");
-	printf("%s: x=%d, y=%d\n", getprogname(), foo.x, foo.y);
+	printf("%s: ioctl(MYDEVIOC_READ)\t-> x=%d, y=%d\n",
+	    getprogname(), bar.x, bar.y);
 
-	foo.x = 1;
-	foo.y = 2;
-	if (ioctl(dev, MYDEVIOC_WRITE, &foo) != 0)
+	printf("%s: ioctl(MYDEVIOC_WRITE)\t-> ", getprogname());
+	fflush(stdout);
+
+	bar.x = 10;
+	bar.y = 20;
+	if (ioctl(fd, MYDEVIOC_WRITE, &bar) != 0)
 		err(1, "ioctl(MYDEVIOC_WRITE)");
 
-	if (ioctl(dev, MYDEVIOC_RDWR, &foo) != 0)
+	if (ioctl(fd, MYDEVIOC_RDWR, &bar) != 0)
 		err(1, "ioctl(MYDEVIOC_RDWR)");
-	printf("%s received: x=%d, y=%d\n", getprogname(), foo.x, foo.y);
+	printf("%s: ioctl(MYDEVIOC_RDWR)\t-> x=%d, y=%d\n",
+	    getprogname(), bar.x, bar.y);
 
-	if (read(dev, buf, sizeof(buf)) < 0)
-		err(1, "read");
-	printf("%s: %s\n", getprogname(), buf);
+	(void)strlcpy(buf, "hello from test program", sizeof(buf));
 
-	strlcpy(buf, "writing to mydev", sizeof(buf));
-	if (write(dev, buf, sizeof(buf)) < 0)
+	printf("%s: write()\t\t\t-> %s\n", getprogname(), buf);
+	fflush(stdout);
+
+	if (write(fd, buf, sizeof(buf)) < 0)
 		err(1, "write");
+	if (read(fd, buf, sizeof(buf)) < 0)
+		err(1, "read");
+	printf("%s: read()\t\t\t-> %s\n", getprogname(), buf);
 
-	close(dev);
+	close(fd);
 
 	return (0);
 }