[PATCH] usbip: usbip_host_common: Use struct_size() in realloc()
From: Gustavo A. R. Silva
Date: Thu May 23 2019 - 10:43:15 EST
One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:
struct foo {
int stuff;
struct boo entry[];
};
size = sizeof(struct foo) + count * sizeof(struct boo);
instance = realloc(instance, size);
Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:
size = struct_size(instance, entry, count);
or
instance = realloc(instance, struct_size(instance, entry, count));
Notice that, in this case, variable size is not necessary,
hence it is removed.
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
---
Notice that checkpatch reports the following warning:
WARNING: line over 80 characters
#57: FILE: tools/usb/usbip/libsrc/usbip_host_common.c:90:
+ edev = realloc(edev, struct_size(edev, uinf, edev->udev.bNumInterfaces));
The line above is 81-character long. So, I think we should be fine
with that, instead of split it into two lines like:
edev = realloc(edev,
struct_size(edev, uinf, edev->udev.bNumInterfaces));
Thanks
--
Gustavo
tools/usb/usbip/libsrc/usbip_host_common.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/tools/usb/usbip/libsrc/usbip_host_common.c b/tools/usb/usbip/libsrc/usbip_host_common.c
index 2813aa821c82..1645d02a52af 100644
--- a/tools/usb/usbip/libsrc/usbip_host_common.c
+++ b/tools/usb/usbip/libsrc/usbip_host_common.c
@@ -67,7 +67,6 @@ struct usbip_exported_device *usbip_exported_device_new(
{
struct usbip_exported_device *edev = NULL;
struct usbip_exported_device *edev_old;
- size_t size;
int i;
edev = calloc(1, sizeof(struct usbip_exported_device));
@@ -87,11 +86,8 @@ struct usbip_exported_device *usbip_exported_device_new(
goto err;
/* reallocate buffer to include usb interface data */
- size = sizeof(struct usbip_exported_device) +
- edev->udev.bNumInterfaces * sizeof(struct usbip_usb_interface);
-
edev_old = edev;
- edev = realloc(edev, size);
+ edev = realloc(edev, struct_size(edev, uinf, edev->udev.bNumInterfaces));
if (!edev) {
edev = edev_old;
dbg("realloc failed");
--
2.21.0