Re: [PATCH] tmpfs: implement generic xattr support

[Miklos Szeredi]

Phillip Lougher <phillip.lougher@xxxxxxxxx> writes:

> On Tue, Apr 19, 2011 at 9:04 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
>
>> +static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
>
>> + Â Â Â spin_lock(&dentry->d_inode->i_lock);
>> + Â Â Â list_for_each_entry(xattr, &info->xattr_list, list) {
>> + Â Â Â Â Â Â Â /* skip "trusted." attributes for unprivileged callers */
>> + Â Â Â Â Â Â Â if (!trusted && xattr_is_trusted(xattr->name))
>> + Â Â Â Â Â Â Â Â Â Â Â continue;
>> +
>> + Â Â Â Â Â Â Â used += strlen(xattr->name) + 1;
>> + Â Â Â Â Â Â Â if (buffer) {
>> + Â Â Â Â Â Â Â Â Â Â Â if (size < used) {
>> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â used = -ERANGE;
>> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â break;
>> + Â Â Â Â Â Â Â Â Â Â Â }
>> + Â Â Â Â Â Â Â Â Â Â Â strncpy(buffer, xattr->name, strlen(xattr->name) + 1);
>>+                        buffer += strlen(xattr->name) + 1;
>
> Why are you doing a strncpy here?  strcpy() isn't going to copy more
> than strlen(xattr->name) + 1 bytes, and you know buffer is large
> enough to hold that because of the previous if (size < used) check?
>
> If you assigned the first strlen(xattr->name) + 1 to a temporary
> variable, you could use memcpy here, and avoid the 3 repeated
> strlen(xattr->name) calls.

Yeah, makes sense.

Thanks,
Miklos
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