Support lseek(2) in ashmem driver
Bjorn Bringert [Thu, 26 Aug 2010 14:08:32 +0000 (15:08 +0100)]
Signed-off-by: Bjorn Bringert <bringert@android.com>
Change-Id: I509d18b21832e229737ea7ebaa231fb107eb61d7

mm/ashmem.c

index b6c5e2a..f92eb34 100644 (file)
@@ -178,7 +178,7 @@ static int ashmem_open(struct inode *inode, struct file *file)
        struct ashmem_area *asma;
        int ret;
 
-       ret = nonseekable_open(inode, file);
+       ret = generic_file_open(inode, file);
        if (unlikely(ret))
                return ret;
 
@@ -230,6 +230,42 @@ static ssize_t ashmem_read(struct file *file, char __user *buf,
        }
 
        ret = asma->file->f_op->read(asma->file, buf, len, pos);
+       if (ret < 0) {
+               goto out;
+       }
+
+       /** Update backing file pos, since f_ops->read() doesn't */
+       asma->file->f_pos = *pos;
+
+out:
+       mutex_unlock(&ashmem_mutex);
+       return ret;
+}
+
+static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin)
+{
+       struct ashmem_area *asma = file->private_data;
+       int ret;
+
+       mutex_lock(&ashmem_mutex);
+
+       if (asma->size == 0) {
+               ret = -EINVAL;
+               goto out;
+       }
+
+       if (!asma->file) {
+               ret = -EBADF;
+               goto out;
+       }
+
+       ret = asma->file->f_op->llseek(asma->file, offset, origin);
+       if (ret < 0) {
+               goto out;
+       }
+
+       /** Copy f_pos from backing file, since f_ops->llseek() sets it */
+       file->f_pos = asma->file->f_pos;
 
 out:
        mutex_unlock(&ashmem_mutex);
@@ -640,6 +676,7 @@ static struct file_operations ashmem_fops = {
        .open = ashmem_open,
        .release = ashmem_release,
         .read = ashmem_read,
+        .llseek = ashmem_llseek,
        .mmap = ashmem_mmap,
        .unlocked_ioctl = ashmem_ioctl,
        .compat_ioctl = ashmem_ioctl,