diff options
| -rw-r--r-- | sys/kern/uipc_mbuf.c | 145 | ||||
| -rw-r--r-- | sys/sys/mbuf.h | 2 |
2 files changed, 147 insertions, 0 deletions
diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c index dd51e51..18281fb 100644 --- a/sys/kern/uipc_mbuf.c +++ b/sys/kern/uipc_mbuf.c @@ -558,6 +558,151 @@ nospace: } /* + * Returns mbuf chain with new head for the prepending case. + * Copies from mbuf (chain) n from off for len to mbuf (chain) m + * either prepending or appending the data. + * The resulting mbuf (chain) m is fully writeable. + * m is destination (is made writeable) + * n is source, off is offset in source, len is len from offset + * dir, 0 append, 1 prepend + * how, wait or nowait + */ + +static int +m_bcopyxxx(void *s, void *t, u_int len) +{ + bcopy(s, t, (size_t)len); + return 0; +} + +struct mbuf * +m_copymdata(struct mbuf *m, struct mbuf *n, int off, int len, + int prep, int how) +{ + struct mbuf *mm, *x, *z; + caddr_t p; + int i, mlen, nlen = 0; + caddr_t buf[MLEN]; + + KASSERT(m != NULL && n != NULL, ("m_copymdata, no target or source")); + KASSERT(off >= 0, ("m_copymdata, negative off %d", off)); + KASSERT(len >= 0, ("m_copymdata, negative len %d", len)); + KASSERT(prep == 0 || prep == 1, ("m_copymdata, unknown direction %d", prep)); + + /* Make sure environment is sane. */ + for (z = m; z != NULL; z = z->m_next) { + mlen += z->m_len; + if (!M_WRITABLE(z)) { + /* Make clusters writeable. */ + if (z->m_flags & M_RDONLY) + return NULL; /* Can't handle ext ref. */ + x = m_getcl(how, MT_DATA, 0); + if (!x) + return NULL; + bcopy(z->m_ext.ext_buf, x->m_ext.ext_buf, x->m_ext.ext_size); + p = x->m_ext.ext_buf + (z->m_data - z->m_ext.ext_buf); + MEXT_REM_REF(z); /* XXX */ + z->m_data = p; + x->m_flags &= ~M_EXT; + (void)m_free(x); + } + } + mm = prep ? m : z; + for (z = n; z != NULL; z = z->m_next) + nlen += z->m_len; + if (len == M_COPYALL) + len = nlen - off; + if (off + len > nlen || len < 1) + return NULL; + + /* + * Append/prepend the data. Allocating mbufs as necessary. + */ + /* Shortcut if enough free space in first/last mbuf. */ + if (!prep && M_TRAILINGSPACE(mm) >= len) { + m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t) + + mm->m_len); + mm->m_len += len; + mm->m_pkthdr.len += len; + return m; + } + if (prep && M_LEADINGSPACE(mm) >= len) { + mm->m_data = mtod(mm, caddr_t) - len; + m_apply(n, off, len, m_bcopyxxx, mtod(mm, caddr_t)); + mm->m_len += len; + mm->m_pkthdr.len += len; + return mm; + } + + /* Expand first/last mbuf to cluster if possible. */ + if (!prep && !(mm->m_flags & M_EXT) && len > M_TRAILINGSPACE(mm)) { + bcopy(mm->m_data, &buf, mm->m_len); + m_clget(mm, how); + if (!(mm->m_flags & M_EXT)) + return NULL; + bcopy(&buf, mm->m_ext.ext_buf, mm->m_len); + mm->m_data = mm->m_ext.ext_buf; + mm->m_pkthdr.header = NULL; + } + if (prep && !(mm->m_flags & M_EXT) && len > M_LEADINGSPACE(mm)) { + bcopy(mm->m_data, &buf, mm->m_len); + m_clget(mm, how); + if (!(mm->m_flags & M_EXT)) + return NULL; + bcopy(&buf, (caddr_t *)mm->m_ext.ext_buf + + mm->m_ext.ext_size - mm->m_len, mm->m_len); + mm->m_data = (caddr_t)mm->m_ext.ext_buf + + mm->m_ext.ext_size - mm->m_len; + mm->m_pkthdr.header = NULL; + } + + /* Append/prepend as many mbuf (clusters) as necessary to fit len. */ + if (!prep && len > M_TRAILINGSPACE(mm)) { + if (!m_getm(mm, len - M_TRAILINGSPACE(mm), how, MT_DATA)) + return NULL; + } + if (prep && len > M_LEADINGSPACE(mm)) { + if (!(z = m_getm(NULL, len - M_LEADINGSPACE(mm), how, MT_DATA))) + return NULL; + i = 0; + for (x = z; x != NULL; x = x->m_next) { + i += x->m_flags & M_EXT ? x->m_ext.ext_size : + (x->m_flags & M_PKTHDR ? MHLEN : MLEN); + if (!x->m_next) + break; + } + z->m_data += i - len; + m_move_pkthdr(mm, z); + x->m_next = mm; + mm = z; + } + + /* Seek to start position in source mbuf. Optimization for long chains. */ + while (off > 0) { + if (off < n->m_len) + break; + off -= n->m_len; + n = n->m_next; + } + + /* Copy data into target mbuf. */ + z = mm; + while (len > 0) { + KASSERT(z != NULL, ("m_copymdata, falling off target edge")); + i = M_TRAILINGSPACE(z); + m_apply(n, off, i, m_bcopyxxx, mtod(z, caddr_t) + z->m_len); + z->m_len += i; + /* fixup pkthdr.len if necessary */ + if ((prep ? mm : m)->m_flags & M_PKTHDR) + (prep ? mm : m)->m_pkthdr.len += i; + off += i; + len -= i; + z = z->m_next; + } + return (prep ? mm : m); +} + +/* * Copy an entire packet, including header (which must be present). * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'. * Note that the copy is read-only, because clusters are not copied, diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h index 55db1b1..7696fa4 100644 --- a/sys/sys/mbuf.h +++ b/sys/sys/mbuf.h @@ -573,6 +573,8 @@ void m_extadd(struct mbuf *, caddr_t, u_int, void m_copyback(struct mbuf *, int, int, c_caddr_t); void m_copydata(const struct mbuf *, int, int, caddr_t); struct mbuf *m_copym(struct mbuf *, int, int, int); +struct mbuf *m_copymdata(struct mbuf *, struct mbuf *, + int, int, int, int); struct mbuf *m_copypacket(struct mbuf *, int); void m_copy_pkthdr(struct mbuf *, struct mbuf *); struct mbuf *m_copyup(struct mbuf *n, int len, int dstoff); |
