diff options
Diffstat (limited to 'sys/kern/uipc_mbuf.c')
| -rw-r--r-- | sys/kern/uipc_mbuf.c | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c index 8a236a6..f5ba9ab 100644 --- a/sys/kern/uipc_mbuf.c +++ b/sys/kern/uipc_mbuf.c @@ -767,6 +767,54 @@ bad: } /* + * Like m_pullup(), except a new mbuf is always allocated, and we allow + * the amount of empty space before the data in the new mbuf to be specified + * (in the event that the caller expects to prepend later). + */ +int MSFail; + +struct mbuf * +m_copyup(struct mbuf *n, int len, int dstoff) +{ + struct mbuf *m; + int count, space; + + if (len > (MHLEN - dstoff)) + goto bad; + MGET(m, M_DONTWAIT, n->m_type); + if (m == NULL) + goto bad; + m->m_len = 0; + if (n->m_flags & M_PKTHDR) + M_MOVE_PKTHDR(m, n); + m->m_data += dstoff; + space = &m->m_dat[MLEN] - (m->m_data + m->m_len); + do { + count = min(min(max(len, max_protohdr), space), n->m_len); + memcpy(mtod(m, caddr_t) + m->m_len, mtod(n, caddr_t), + (unsigned)count); + len -= count; + m->m_len += count; + n->m_len -= count; + space -= count; + if (n->m_len) + n->m_data += count; + else + n = m_free(n); + } while (len > 0 && n); + if (len > 0) { + (void) m_free(m); + goto bad; + } + m->m_next = n; + return (m); + bad: + m_freem(n); + MSFail++; + return (NULL); +} + +/* * Partition an mbuf chain in two pieces, returning the tail -- * all but the first len0 bytes. In case of failure, it returns NULL and * attempts to restore the chain to its original state. |
