diff options
| author | Thomas Graf <tgraf@suug.ch> | 2013-03-13 16:53:07 +0100 |
|---|---|---|
| committer | Thomas Graf <tgraf@suug.ch> | 2013-03-14 12:46:01 +0100 |
| commit | 9e6cdbf6fc60f95e232c4ca34004606da9536d01 (patch) | |
| tree | 16ee3ee5574e986e1875df669cba6c541c0aaffb | |
| parent | 4d7680c19c131175e2ec431de9a026230c968a7e (diff) | |
attr: Add nla_nest_cancel() to remove partially added nested attributes
Signed-off-by: Thomas Graf <tgraf@suug.ch>
| -rw-r--r-- | doc/core.txt | 1 | ||||
| -rw-r--r-- | include/netlink/attr.h | 1 | ||||
| -rw-r--r-- | lib/attr.c | 25 |
3 files changed, 25 insertions, 2 deletions
diff --git a/doc/core.txt b/doc/core.txt index 8a26dba..1e951d0 100644 --- a/doc/core.txt +++ b/doc/core.txt @@ -2316,6 +2316,7 @@ int put_opts(struct nl_msg *msg) return 0; nla_put_failure: + nla_nest_cancel(msg, opts); return -EMSGSIZE; } -------- diff --git a/include/netlink/attr.h b/include/netlink/attr.h index 69ecb08..0ed3da3 100644 --- a/include/netlink/attr.h +++ b/include/netlink/attr.h @@ -124,6 +124,7 @@ extern int nla_put_msecs(struct nl_msg *, int, unsigned long); extern int nla_put_nested(struct nl_msg *, int, struct nl_msg *); extern struct nlattr * nla_nest_start(struct nl_msg *, int); extern int nla_nest_end(struct nl_msg *, struct nlattr *); +extern void nla_nest_cancel(struct nl_msg *, struct nlattr *); extern int nla_parse_nested(struct nlattr **, int, struct nlattr *, struct nla_policy *); extern int nla_is_nested(struct nlattr *); @@ -820,8 +820,7 @@ int nla_nest_end(struct nl_msg *msg, struct nlattr *start) * Kernel can't handle empty nested attributes, trim the * attribute header again */ - msg->nm_nlh->nlmsg_len -= NLA_HDRLEN; - memset(nlmsg_tail(msg->nm_nlh), 0, NLA_HDRLEN); + nla_nest_cancel(msg, start); return 0; } @@ -850,6 +849,28 @@ int nla_nest_end(struct nl_msg *msg, struct nlattr *start) } /** + * Cancel the addition of a nested attribute + * @arg msg Netlink message + * @arg attr Nested netlink attribute + * + * Removes any partially added nested Netlink attribute from the message + * by resetting the message to the size before the call to nla_nest_start() + * and by overwriting any potentially touched message segments with 0. + */ +void nla_nest_cancel(struct nl_msg *msg, struct nlattr *attr) +{ + ssize_t len; + + len = (void *) nlmsg_tail(msg->nm_nlh) - (void *) attr; + if (len < 0) + BUG(); + else if (len > 0) { + msg->nm_nlh->nlmsg_len -= len; + memset(nlmsg_tail(msg->nm_nlh), 0, len); + } +} + +/** * Create attribute index based on nested attribute * @arg tb Index array to be filled (maxtype+1 elements). * @arg maxtype Maximum attribute type expected and accepted. |