/* Needed for copying to/from user space */
#include <asm/uaccess.h>
#include <linux/slab.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>");
MODULE_DESCRIPTION("A hello world char device");
MODULE_VERSION("1.0.0");
-/* Message buffer we send to upstream */
-static char hello_message[] = "hello, world\n";
-static char goodbye_message[] = "goodbye, world\n";
+#define BUFFER_SIZE 4096
+#define DEVICE_NUMBER 2
struct message {
char *text;
size_t len;
};
+/* Message buffer we send to upstream */
+static struct message *hello_message[DEVICE_NUMBER];
+
static int helloc_open(struct inode *ino, struct file *filp)
{
struct message *msg;
printk(KERN_INFO "Opened file with minor %d\n", iminor(ino));
- msg = kmalloc(sizeof(struct message), GFP_KERNEL);
- if (!msg)
- return -ENOMEM;
- if (iminor(ino) == 0) {
- msg->text = hello_message;
- msg->len = sizeof(hello_message);
- } else {
- msg->text = goodbye_message;
- msg->len = sizeof(goodbye_message);
- }
+ if (iminor(ino) >= DEVICE_NUMBER)
+ return -ENODEV;
+ msg = hello_message[iminor(ino)];
filp->private_data = msg;
+ if (filp->f_flags & O_TRUNC) {
+ memset(msg->text, 0, msg->len);
+ msg->len = 0;
+ printk(KERN_INFO "File opened with truncate flags\n");
+ }
+ if (filp->f_flags & O_APPEND) {
+ filp->f_pos = msg->len;
+ }
return 0;
}
static int helloc_release(struct inode *ino, struct file *filp)
{
- kfree(filp->private_data);
return 0;
}
return len;
}
+static ssize_t helloc_write(struct file *filp, const char __user *buf,
+ size_t len, loff_t *pos)
+{
+ int r;
+ struct message *msg = filp->private_data;
+ /* do not read pass through the size of the message */
+ if (*pos >= BUFFER_SIZE)
+ /* return end of file */
+ return 0;
+ /* if len is bigger than the rest of the message, clamp it */
+ if (len > BUFFER_SIZE - *pos)
+ len = BUFFER_SIZE - *pos;
+
+ /* copy message to user space and return error if it fails */
+ r = copy_from_user(msg->text + *pos, buf, len);
+ if (r) {
+ if (*pos + len > msg->len)
+ memset(msg->text + msg->len, 0, *pos + len - msg->len);
+ return -EFAULT;
+ }
+ /* update the file position */
+ *pos += len;
+ if (msg->len < *pos) {
+ printk(KERN_DEBUG "Updating size from %d to %lld\n", msg->len, *pos);
+ msg->len = *pos;
+ }
+
+ return len;
+}
+
/* we only implement read */
static struct file_operations helloc_fops = {
.owner = THIS_MODULE,
.open = helloc_open,
.release = helloc_release,
.read = helloc_read,
+ .write = helloc_write,
};
+static int hello_len_show(struct seq_file *seq, void *data)
+{
+ struct message *msg = seq->private;
+ seq_printf(seq, "%d\n", msg->len);
+ return 0;
+}
+
+static int hello_proc_open(struct inode *ino, struct file *filp)
+{
+ return single_open(filp, hello_len_show, hello_message[0]);
+}
+
+static struct file_operations hello_proc_fops = {
+ .owner = THIS_MODULE,
+ .open = hello_proc_open,
+ .llseek = seq_lseek,
+ .read = seq_read,
+ .release = seq_release,
+};
+
+
/* the device number and the char device struct */
static dev_t dev;
static struct cdev *cdev;
+static void helloc_free(void)
+{
+ int i;
+ for (i = 0; i < DEVICE_NUMBER; i++) {
+ if (hello_message[i])
+ kfree(hello_message[i]->text);
+ kfree(hello_message[i]);
+ }
+}
+
+static int __init helloc_alloc(void)
+{
+ int i;
+ for (i = 0; i < DEVICE_NUMBER; i++) {
+ hello_message[i] = kzalloc(sizeof(struct message), GFP_KERNEL);
+ if (!hello_message[i])
+ goto out;
+ hello_message[i]->text = kzalloc(BUFFER_SIZE, GFP_KERNEL);
+ if (!hello_message[i]->text)
+ goto out;
+ }
+ return 0;
+out:
+ for (; i >= 0; i--) {
+ if (hello_message[i])
+ kfree(hello_message[i]->text);
+ kfree(hello_message[i]);
+ }
+ return -ENOMEM;
+}
+
static int __init helloc_init(void)
{
+ struct proc_dir_entry *hello_pde;
int r;
+ r = helloc_alloc();
+ if (r)
+ goto out_alloc2;
/* allocate any major number with only one minor */
- r = alloc_chrdev_region(&dev, 0, 2, "helloc");
+ r = alloc_chrdev_region(&dev, 0, DEVICE_NUMBER, "helloc");
if (r)
goto out_region;
r = -ENOMEM;
cdev->owner = THIS_MODULE;
cdev->ops = &helloc_fops;
/* register the chardev to the system */
- r = cdev_add(cdev, dev, 2);
+ r = cdev_add(cdev, dev, DEVICE_NUMBER);
if (r)
goto out_add;
+ hello_pde = proc_create("hello_len", 0666, NULL, &hello_proc_fops);
+ if (!hello_pde)
+ goto out_pde;
return 0;
+out_pde:
+ cdev_del(cdev);
out_add:
/* release memory allocated to the cdev device */
kfree(cdev);
out_alloc:
/* release the device number allocated */
- unregister_chrdev_region(dev, 2);
+ unregister_chrdev_region(dev, DEVICE_NUMBER);
out_region:
+out_alloc2:
return r;
}
static void __exit helloc_exit(void)
{
+ remove_proc_entry("hello_len", NULL);
/* remove the chardev from the system */
cdev_del(cdev);
/* release the device number allocated */
- unregister_chrdev_region(dev, 2);
+ unregister_chrdev_region(dev, DEVICE_NUMBER);
+ helloc_free();
}
module_init(helloc_init);
projects / cascardo / kernel / samples / 02.char / .git / blobdiff