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netlink: add nla_policy_len()

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It calculates the max. length of a Netlink policy, which is usefull
for allocating Netlink buffers roughly the size of the actual
message.

Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Holger Eitzenberger 2009-03-25 18:26:30 +01:00 committed by Patrick McHardy
parent d0dba7255b
commit e487eb99cf
2 changed files with 28 additions and 0 deletions
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1
include/net/netlink.h
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@ -230,6 +230,7 @@ extern int nla_validate(struct nlattr *head, int len, int maxtype,
extern int nla_parse(struct nlattr *tb[], int maxtype,
struct nlattr *head, int len,
const struct nla_policy *policy);
extern int nla_policy_len(const struct nla_policy *, int);
extern struct nlattr * nla_find(struct nlattr *head, int len, int attrtype);
extern size_t nla_strlcpy(char *dst, const struct nlattr *nla,
size_t dstsize);

27
net/netlink/attr.c
View File

@ -132,6 +132,32 @@ errout:
return err;
}
/**
* nla_policy_len - Determin the max. length of a policy
* @policy: policy to use
* @n: number of policies
*
* Determines the max. length of the policy. It is currently used
* to allocated Netlink buffers roughly the size of the actual
* message.
*
* Returns 0 on success or a negative error code.
*/
int
nla_policy_len(const struct nla_policy *p, int n)
{
int i, len = 0;
for (i = 0; i < n; i++) {
if (p->len)
len += nla_total_size(p->len);
else if (nla_attr_minlen[p->type])
len += nla_total_size(nla_attr_minlen[p->type]);
}
return len;
}
/**
* nla_parse - Parse a stream of attributes into a tb buffer
* @tb: destination array with maxtype+1 elements
@ -456,6 +482,7 @@ int nla_append(struct sk_buff *skb, int attrlen, const void *data)
}
EXPORT_SYMBOL(nla_validate);
EXPORT_SYMBOL(nla_policy_len);
EXPORT_SYMBOL(nla_parse);
EXPORT_SYMBOL(nla_find);
EXPORT_SYMBOL(nla_strlcpy);