1 files changed, 72 insertions, 0 deletions
diff --git a/assoc_buf.h b/assoc_buf.h
new file mode 100644
index 0000000..e9e7fbc
--- /dev/null
+++ b/assoc_buf.h
@@ -0,0 +1,72 @@
+#include <linux/slab.h>
+#include <linux/kernel.h>
+
+struct asbuf {
+    unsigned long ino;
+    char *buf;
+    size_t alloc;
+};
+
+
+ssize_t asbuf_free_alloc(struct asbuf *buf, size_t size) {
+    char *mem;
+
+    mem = kmalloc(size, GFP_KERNEL);
+    if (!mem)
+        return -ENOMEM;
+
+    if (buf->alloc)
+        kfree(buf->buf);
+
+    buf->buf = mem;
+    buf->alloc = size;
+    return 0;
+}
+
+void asbuf_free(struct asbuf *buf) {
+    kfree(buf->buf);
+}
+
+ssize_t asbuf_to_user(struct asbuf *buf,
+                      char __user *user_buf,
+                      size_t len,
+                      loff_t *offset) {
+
+    size_t chars_left, request;
+    ssize_t uncopied, copied;
+
+    if (!buf->alloc)
+        return -EINVAL;
+
+    if (*offset > buf->alloc)
+        return -EINVAL;
+
+    chars_left = buf->alloc - *offset;
+    request = min(len, chars_left);
+
+    printk(KERN_INFO "buf: %p\t alloc: %zu\t request: %zu\n", buf, buf->alloc, request);
+
+    uncopied = copy_to_user(user_buf, buf->buf + *offset, request);
+    copied = request - uncopied;
+
+    *offset += copied;
+    return copied;
+}
+
+ssize_t asbuf_from_user(struct asbuf *buf,
+                        const char __user *user_buf,
+                        size_t len,
+                        loff_t *offset) {
+    ssize_t rc = 0;
+    size_t uncopied, copied;
+    rc = asbuf_free_alloc(buf, len);
+    if (rc != 0)
+        return rc;
+
+    uncopied = copy_from_user(buf->buf, user_buf, len);
+    copied = len - uncopied;
+
+    *offset = 0;
+
+    return copied;
+}