V4L/DVB (12543): v4l: introduce string control support.

The upcoming RDS encoder needs support for string controls. This patch
implements the core implementation.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

3 files changed, 53 insertions, 24 deletions

diff --git a/drivers/media/video/v4l2-common.c b/drivers/media/video/v4l2-common.c
index b91d66a767d7..536150c34067 100644
--- a/drivers/media/video/v4l2-common.c
+++ b/drivers/media/video/v4l2-common.c
@@ -156,6 +156,8 @@ int v4l2_ctrl_check(struct v4l2_ext_control *ctrl, struct v4l2_queryctrl *qctrl,
                 return -EINVAL;
         if (qctrl->flags & V4L2_CTRL_FLAG_GRABBED)
                 return -EBUSY;
+        if (qctrl->type == V4L2_CTRL_TYPE_STRING)
+                return 0;
         if (qctrl->type == V4L2_CTRL_TYPE_BUTTON ||
             qctrl->type == V4L2_CTRL_TYPE_INTEGER64 ||
             qctrl->type == V4L2_CTRL_TYPE_CTRL_CLASS)
diff --git a/drivers/media/video/v4l2-compat-ioctl32.c b/drivers/media/video/v4l2-compat-ioctl32.c
index 0056b115b42e..f788c41a3a5c 100644
--- a/drivers/media/video/v4l2-compat-ioctl32.c
+++ b/drivers/media/video/v4l2-compat-ioctl32.c
@@ -600,9 +600,35 @@ struct v4l2_ext_controls32 {
        compat_caddr_t controls; /* actually struct v4l2_ext_control32 * */
 };
 
+struct v4l2_ext_control32 {
+        __u32 id;
+        __u32 size;
+        __u32 reserved2[1];
+        union {
+                __s32 value;
+                __s64 value64;
+                compat_caddr_t string; /* actually char * */
+        };
+} __attribute__ ((packed));
+
+/* The following function really belong in v4l2-common, but that causes
+   a circular dependency between modules. We need to think about this, but
+   for now this will do. */
+
+/* Return non-zero if this control is a pointer type. Currently only
+ * type STRING is a pointer type.
+ *
+ * Note that there are currently no controls of this type, but at least the
+ * compat32 code is in place to properly handle such controls. Please
+ * remove this note once the first pointer controls are added. */
+static inline int ctrl_is_pointer(u32 id)
+{
+        return 0;
+}
+
 static int get_v4l2_ext_controls32(struct v4l2_ext_controls *kp, struct v4l2_ext_controls32 __user *up)
 {
-        struct v4l2_ext_control __user *ucontrols;
+        struct v4l2_ext_control32 __user *ucontrols;
         struct v4l2_ext_control __user *kcontrols;
         int n;
         compat_caddr_t p;
@@ -626,15 +652,17 @@ static int get_v4l2_ext_controls32(struct v4l2_ext_controls *kp, struct v4l2_ext
         kcontrols = compat_alloc_user_space(n * sizeof(struct v4l2_ext_control));
         kp->controls = kcontrols;
         while (--n >= 0) {
-                if (copy_in_user(&kcontrols->id, &ucontrols->id, sizeof(__u32)))
-                        return -EFAULT;
-                if (copy_in_user(&kcontrols->reserved2, &ucontrols->reserved2, sizeof(ucontrols->reserved2)))
-                        return -EFAULT;
-                /* Note: if the void * part of the union ever becomes relevant
-                   then we need to know the type of the control in order to do
-                   the right thing here. Luckily, that is not yet an issue. */
-                if (copy_in_user(&kcontrols->value, &ucontrols->value, sizeof(ucontrols->value)))
+                if (copy_in_user(kcontrols, ucontrols, sizeof(*kcontrols)))
                         return -EFAULT;
+                if (ctrl_is_pointer(kcontrols->id)) {
+                        void __user *s;
+
+                        if (get_user(p, &ucontrols->string))
+                                return -EFAULT;
+                        s = compat_ptr(p);
+                        if (put_user(s, &kcontrols->string))
+                                return -EFAULT;
+                }
                 ucontrols++;
                 kcontrols++;
         }
@@ -643,7 +671,7 @@ static int get_v4l2_ext_controls32(struct v4l2_ext_controls *kp, struct v4l2_ext
 
 static int put_v4l2_ext_controls32(struct v4l2_ext_controls *kp, struct v4l2_ext_controls32 __user *up)
 {
-        struct v4l2_ext_control __user *ucontrols;
+        struct v4l2_ext_control32 __user *ucontrols;
         struct v4l2_ext_control __user *kcontrols = kp->controls;
         int n = kp->count;
         compat_caddr_t p;
@@ -664,15 +692,14 @@ static int put_v4l2_ext_controls32(struct v4l2_ext_controls *kp, struct v4l2_ext
                 return -EFAULT;
 
         while (--n >= 0) {
-                if (copy_in_user(&ucontrols->id, &kcontrols->id, sizeof(__u32)))
-                        return -EFAULT;
-                if (copy_in_user(&ucontrols->reserved2, &kcontrols->reserved2,
-                                        sizeof(ucontrols->reserved2)))
-                        return -EFAULT;
-                /* Note: if the void * part of the union ever becomes relevant
-                   then we need to know the type of the control in order to do
-                   the right thing here. Luckily, that is not yet an issue. */
-                if (copy_in_user(&ucontrols->value, &kcontrols->value, sizeof(ucontrols->value)))
+                unsigned size = sizeof(*ucontrols);
+
+                /* Do not modify the pointer when copying a pointer control.
+                   The contents of the pointer was changed, not the pointer
+                   itself. */
+                if (ctrl_is_pointer(kcontrols->id))
+                        size -= sizeof(ucontrols->value64);
+                if (copy_in_user(ucontrols, kcontrols, size))
                         return -EFAULT;
                 ucontrols++;
                 kcontrols++;
diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index c32e67608ad4..30cc3347ae52 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -513,11 +513,12 @@ static inline void v4l_print_ext_ctrls(unsigned int cmd,
         dbgarg(cmd, "");
         printk(KERN_CONT "class=0x%x", c->ctrl_class);
         for (i = 0; i < c->count; i++) {
-                if (show_vals)
+                if (show_vals && !c->controls[i].size)
                         printk(KERN_CONT " id/val=0x%x/0x%x",
                                 c->controls[i].id, c->controls[i].value);
                 else
-                        printk(KERN_CONT " id=0x%x", c->controls[i].id);
+                        printk(KERN_CONT " id=0x%x,size=%u",
+                                c->controls[i].id, c->controls[i].size);
         }
         printk(KERN_CONT "\n");
 };
@@ -528,10 +529,9 @@ static inline int check_ext_ctrls(struct v4l2_ext_controls *c, int allow_priv)
 
         /* zero the reserved fields */
         c->reserved[0] = c->reserved[1] = 0;
-        for (i = 0; i < c->count; i++) {
+        for (i = 0; i < c->count; i++)
                 c->controls[i].reserved2[0] = 0;
-                c->controls[i].reserved2[1] = 0;
-        }
+
         /* V4L2_CID_PRIVATE_BASE cannot be used as control class
            when using extended controls.
            Only when passed in through VIDIOC_G_CTRL and VIDIOC_S_CTRL