Implement read(2) in ashmem driver

Bug: 2595601
Change-Id: I47c0016f594f9354fb8658ccb26e3d395bcb137b
Signed-off-by: Bjorn Bringert <bringert@android.com>

diff --git a/mm/ashmem.c b/mm/ashmem.c
index 230810f9387cc1431525a5fe23fdff50dac68c3d..04e886e2c9092dd5c15afb1c81b22889106e0cea 100644 (file)
--- a/mm/ashmem.c
+++ b/mm/ashmem.c
@@ -211,6 +211,31 @@ static int ashmem_release(struct inode *ignored, struct file *file)
        return 0;
 }
 
+static ssize_t ashmem_read(struct file *file, char __user *buf,
+                          size_t len, loff_t *pos)
+{
+       struct ashmem_area *asma = file->private_data;
+       int ret = 0;
+
+       mutex_lock(&ashmem_mutex);
+
+       /* If size is not set, or set to 0, always return EOF. */
+       if (asma->size == 0) {
+               goto out;
+        }
+
+       if (!asma->file) {
+               ret = -EBADF;
+               goto out;
+       }
+
+       ret = asma->file->f_op->read(asma->file, buf, len, pos);
+
+out:
+       mutex_unlock(&ashmem_mutex);
+       return ret;
+}
+
 static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
 {
        struct ashmem_area *asma = file->private_data;
@@ -604,6 +629,7 @@ static struct file_operations ashmem_fops = {
        .owner = THIS_MODULE,
        .open = ashmem_open,
        .release = ashmem_release,
+        .read = ashmem_read,
        .mmap = ashmem_mmap,
        .unlocked_ioctl = ashmem_ioctl,
        .compat_ioctl = ashmem_ioctl,