X-Git-Url: http://git.cascardo.eti.br/?a=blobdiff_plain;f=hellochar.c;h=628f53cd32c208fcc4c3b6f9a5478acc75ff59f0;hb=0ac89f0fe059f1985e9ad39c15794938b5eda7fd;hp=c2eecefc0477cbd9063b9ef84ea4ba363090c8bc;hpb=0c53df020c7b9a4bade2010a3eb260c4318e48f8;p=cascardo%2Fkernel%2Fsamples%2Fchar2%2F.git

diff --git a/hellochar.c b/hellochar.c
index c2eecef..628f53c 100644
--- a/hellochar.c
+++ b/hellochar.c
@@ -20,29 +20,99 @@
 #include <linux/fs.h>
 #include <linux/cdev.h>
 #include <linux/slab.h>
+#include <linux/semaphore.h>
+#include <asm/uaccess.h>
 
 MODULE_LICENSE("GPL");
 
+#define MAXLEN 4000
 static dev_t devnum;
 static struct cdev *dev;
+static const char default_greeting[] = "Hello, World!\n";
+
+struct hello_buffer {
+	size_t len;
+	char buffer[0];
+};
+static struct hello_buffer *hello;
+static DECLARE_MUTEX(hello_mtx);
 
 static int hello_open(struct inode *ino, struct file *fp)
 {
-	printk(KERN_DEBUG "Hello, World!\n");
+	if (down_interruptible(&hello_mtx))
+		return -ERESTARTSYS;
+	if (fp->f_flags & O_TRUNC) {
+		memset(hello->buffer, 0, MAXLEN);
+		hello->len = 0;
+	}
+	if (fp->f_flags & O_APPEND)
+		fp->f_pos = hello->len;
+	up(&hello_mtx);
+	return 0;
+}
+
+static ssize_t hello_read(struct file *fp, char __user *buf, size_t sz,
+	loff_t *pos)
+{
+	int r;
+	if (down_interruptible(&hello_mtx))
+		return -ERESTARTSYS;
+	if (sz + *pos > hello->len)
+		sz = hello->len - *pos;
+	r = copy_to_user(buf, hello->buffer + *pos, sz);
+	up(&hello_mtx);
+	if (r)
+		return -EFAULT;
+	*pos += sz;
+	return sz;
+}
+
+static ssize_t hello_write(struct file *fp, const char __user *buf, size_t sz,
+	loff_t *pos)
+{
+	int r;
+	if (down_interruptible(&hello_mtx))
+		return -ERESTARTSYS;
+	if (sz + *pos > MAXLEN)
+		sz = MAXLEN - *pos;
+	r = copy_from_user(hello->buffer + *pos, buf, sz);
+	if (r) {
+		up(&hello_mtx);
+		return -EFAULT;
+	}
+	*pos += sz;
+	if (hello->len < *pos)
+		hello->len = *pos;
+	up(&hello_mtx);
+	return sz;
+}
+
+static int hello_release(struct inode *ino, struct file *fp)
+{
 	return 0;
 }
 
 static const struct file_operations hello_fops = {
 	.owner = THIS_MODULE,
 	.open = hello_open,
+	.release = hello_release,
+	.read = hello_read,
+	.write = hello_write,
 };
 
 static int __init ch_init(void)
 {
 	int r = 0;
+	hello = kzalloc(sizeof(*hello) + MAXLEN, GFP_KERNEL);
+	if (!hello) {
+		r = -ENOMEM;
+		goto out;
+	}
+	memcpy(hello->buffer, default_greeting, sizeof(default_greeting));
+	hello->len = sizeof(default_greeting);
 	r = alloc_chrdev_region(&devnum, 0, 256, "hello");
 	if (r)
-		goto out;
+		goto reg_out;
 	dev = cdev_alloc();
 	if (!dev) {
 		r = -ENOMEM;
@@ -58,6 +128,8 @@ add_out:
 	kfree(dev);
 cdev_out:
 	unregister_chrdev_region(devnum, 256);
+reg_out:
+	kfree(hello);
 out:
 	return r;
 }
@@ -65,8 +137,8 @@ out:
 static void __exit ch_exit(void)
 {
 	cdev_del(dev);
-	kfree(dev);
 	unregister_chrdev_region(devnum, 256);
+	kfree(hello);
 }
 
 module_init(ch_init);