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Add m_mbuftouio() helper function to copy(out) an arbitrary

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long mbuf chain into an arbitrary large uio in a single step.
It is a functional mirror image of m_uiotombuf().

This function is supposed to be used instead of hand rolled code
with the same purpose and to concentrate it into one place for
potential further optimization or hardware assistance.
This commit is contained in:
andre 2009-06-22 22:20:38 +00:00
parent 7bb0d366d6
commit 74f8982f2f
2 changed files with 29 additions and 0 deletions
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28
sys/kern/uipc_mbuf.c
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@ -1769,6 +1769,34 @@ m_uiotombuf(struct uio *uio, int how, int len, int align, int flags)
return (m);
}
/*
* Copy an mbuf chain into a uio limited by len if set.
*/
int
m_mbuftouio(struct uio *uio, struct mbuf *m, int len)
{
int error, length, total;
int progress = 0;
if (len > 0)
total = min(uio->uio_resid, len);
else
total = uio->uio_resid;
/* Fill the uio with data from the mbufs. */
for (; m != NULL; m = m->m_next) {
length = min(m->m_len, total - progress);
error = uiomove(mtod(m, void *), length, uio);
if (error)
return (error);
progress += length;
}
return (0);
}
/*
* Set the m_data pointer of a newly-allocated mbuf
* to place an object of the specified size at the

1
sys/sys/mbuf.h
View File

@ -813,6 +813,7 @@ void m_freem(struct mbuf *);
struct mbuf *m_getm2(struct mbuf *, int, int, short, int);
struct mbuf *m_getptr(struct mbuf *, int, int *);
u_int m_length(struct mbuf *, struct mbuf **);
int m_mbuftouio(struct uio *, struct mbuf *, int);
void m_move_pkthdr(struct mbuf *, struct mbuf *);
struct mbuf *m_prepend(struct mbuf *, int, int);
void m_print(const struct mbuf *, int);