/**
* Discard `n_bytes' from the pmsg_t buffer slist and free all completely
* discarded buffers.
*/
void
pmsg_slist_discard(slist_t *slist, size_t n_bytes)
{
slist_iter_t *iter;
g_assert(slist);
iter = slist_iter_removable_on_head(slist);
while (n_bytes > 0) {
pmsg_t *mb;
size_t size;
g_assert(slist_iter_has_item(iter));
mb = slist_iter_current(iter);
pmsg_check_consistency(mb);
size = pmsg_size(mb);
if (size > n_bytes) {
pmsg_discard(mb, n_bytes);
break;
} else {
pmsg_free(mb);
n_bytes -= size;
slist_iter_remove(iter);
}
}
slist_iter_free(&iter);
}
/**
* Set the pre-send hook routine for the buffer.
*
* This routine, if it exists (non-NULL) is called just before sending
* the message at the lowest level. If it returns FALSE, the message is
* immediately dropped.
*
* The callback routine must not modify the message.
*
* The difference with a "check callback" is that a hook is only invoked
* on the standalone buffer, the layer perusing this information being
* able to gather all its context from the message, using its protocol header
* relevant to the layer.
*/
void
pmsg_set_hook(pmsg_t *mb, pmsg_hook_t hook)
{
pmsg_check_consistency(mb);
mb->m_u.m_hook = hook;
mb->m_flags |= PMSG_PF_HOOK; /* Is a hook */
}
/**
* Set the pre-send checking routine for the buffer.
*
* This routine, if it exists (non-NULL) is called just before enqueueing
* the message for sending. If it returns FALSE, the message is immediately
* dropped.
*
* The callback routine must not modify the message, as the buffer can
* be shared among multiple messages, unless its refcount is 1.
*/
void
pmsg_set_check(pmsg_t *mb, pmsg_check_t check)
{
pmsg_check_consistency(mb);
mb->m_u.m_check = check;
mb->m_flags &= ~PMSG_PF_HOOK; /* Is not a hook */
}
/**
* Reset message block, discarding all the data buffered and restoring the
* state it had after creation. Upon return, it can be used as if a brand
* new message block had been created.
*/
void
pmsg_reset(pmsg_t *mb)
{
pmsg_check_consistency(mb);
mb->m_rptr = mb->m_wptr = mb->m_data->d_arena; /* Empty buffer */
mb->m_flags = PMSG_EXT_MAGIC == mb->magic ? PMSG_PF_EXT : 0;
mb->m_u.m_check = NULL; /* Clear "pre-send" checks */
}
/**
* Copy ``len'' bytes from the source message block to the destination by
* reading the source bytes and writing them to the recipient.
*
* @returns amount of bytes written, which may be lower than the requested
* amount if the source buffer was shorter or there is not enough room in
* the destination.
*/
int
pmsg_copy(pmsg_t *dest, pmsg_t *src, int len)
{
int copied, available;
pmsg_check_consistency(dest);
pmsg_check_consistency(src);
g_assert(pmsg_is_writable(dest)); /* Not shared, or would corrupt data */
copied = src->m_wptr - src->m_rptr; /* Available data in source */
copied = MIN(copied, len);
available = pmsg_available(dest); /* Room in destination buffer */
copied = MIN(copied, available);
if (copied > 0) {
dest->m_wptr = mempcpy(dest->m_wptr, src->m_rptr, copied);
src->m_rptr += copied;
}
return copied;
}
/**
* Increase the reference count on the message block.
*
* This must be used in TX stacks when there is a free routine installed
* on messages and we want to keep another reference to the message, yet
* allow upper layers to pmsg_free() the message block as if it had been
* sent from their point of view.
*
* It also allows correct pmsg_was_sent() checks in free routines, whereas
* a pmsg_clone() would create a new message.
*
* @return its argument, for convenience.
*/
pmsg_t *
pmsg_ref(pmsg_t *mb)
{
pmsg_check_consistency(mb);
g_assert(mb->m_refcnt != 0);
mb->m_refcnt++;
g_assert(mb->m_refcnt != 0); /* Safeguard against overflows */
return mb;
}
/**
* Shallow cloning of message, making sure we have a plain clone even if
* the original was extended.
*/
pmsg_t *
pmsg_clone_plain(const pmsg_t *mb)
{
pmsg_t *nmb;
pmsg_check_consistency(mb);
WALLOC(nmb);
memcpy(nmb, mb, sizeof *nmb);
nmb->magic = PMSG_MAGIC; /* Force plain message */
nmb->m_flags &= ~PMSG_PF_EXT; /* In case original was extended */
nmb->m_refcnt = 1;
pdata_addref(nmb->m_data);
return nmb;
}
/**
* Read data from the message, returning the amount of bytes transferred.
*/
int
pmsg_read(pmsg_t *mb, void *data, int len)
{
int available, readable;
pmsg_check_consistency(mb);
available = mb->m_wptr - mb->m_rptr;
g_assert(available >= 0); /* Data cannot go beyond end of arena */
readable = len >= available ? available : len;
if (readable != 0) {
memcpy(data, mb->m_rptr, readable);
mb->m_rptr += readable;
}
return readable;
}
/**
* @return amount of data that can be written at the end of the message.
*/
int
pmsg_writable_length(const pmsg_t *mb)
{
pdata_t *arena;
int available;
pmsg_check_consistency(mb);
/*
* If buffer is not writable (shared among several readers), it is
* forbidden to write any new data to it.
*/
arena = mb->m_data;
available = arena->d_end - mb->m_wptr;
return pmsg_is_writable(mb) ? available : 0;
}
/**
* Shallow cloning of message, result is referencing the same data.
*
* This is not the same thing as pmsg_ref() because here a new message block
* is created (albeit the data are shared with the original message).
*/
pmsg_t *
pmsg_clone(pmsg_t *mb)
{
if (pmsg_is_extended(mb)) {
return pmsg_clone_ext(cast_to_pmsg_ext(mb));
} else {
pmsg_t *nmb;
pmsg_check_consistency(mb);
WALLOC(nmb);
*nmb = *mb; /* Struct copy */
nmb->m_refcnt = 1;
pdata_addref(nmb->m_data);
return nmb;
}
}
/**
* Discard trailing data from the message, returning the amount of
* bytes discarded.
*/
int
pmsg_discard_trailing(pmsg_t *mb, int len)
{
int available, n;
pmsg_check_consistency(mb);
available = mb->m_wptr - mb->m_rptr;
g_assert(available >= 0); /* Data cannot go beyond end of arena */
/*
* The write pointer moves backward to point before the discarded bytes.
*/
n = len >= available ? available : len;
mb->m_wptr -= n;
return n;
}
/**
* Discard data from the message, returning the amount of bytes discarded.
*/
int
pmsg_discard(pmsg_t *mb, int len)
{
int available, n;
pmsg_check_consistency(mb);
available = mb->m_wptr - mb->m_rptr;
g_assert(available >= 0); /* Data cannot go beyond end of arena */
/*
* The read pointer moves forward to point after the discarded bytes.
*/
n = len >= available ? available : len;
mb->m_rptr += n;
return n;
}
/**
* Split a buffer at given offset: the data before that offset are left in
* the original buffer whilst the data starting at the offset (included)
* are moved to a new buffer. The original buffer no longer holds the data
* starting at the offset.
*
* @return new message block containing the data starting at the offset.
*/
pmsg_t *
pmsg_split(pmsg_t *mb, int offset)
{
int slen; /* Split length */
const char *start;
g_assert(offset >= 0);
g_assert(offset < pmsg_size(mb));
pmsg_check_consistency(mb);
start = mb->m_rptr + offset;
slen = mb->m_wptr - start;
g_assert(slen > 0);
mb->m_wptr -= slen; /* Logically removed */
return pmsg_new(mb->m_prio, start, slen); /* Copies data */
}
/**
* Shift back unread data to the beginning of the buffer.
*/
void
pmsg_compact(pmsg_t *mb)
{
int shifting;
pmsg_check_consistency(mb);
g_assert(pmsg_is_writable(mb)); /* Not shared, or would corrupt data */
g_assert(mb->m_rptr <= mb->m_wptr);
shifting = mb->m_rptr - mb->m_data->d_arena;
g_assert(shifting >= 0);
if (shifting != 0) {
memmove(mb->m_data->d_arena, mb->m_rptr, pmsg_size(mb));
mb->m_rptr -= shifting;
mb->m_wptr -= shifting;
}
}
/**
* Creates an iovec from a singly-linked list of pmsg_t buffers.
* It should be freed via hfree().
*
* NOTE: The iovec will hold no more than MAX_IOV_COUNT items. That means
* the iovec might not cover the whole buffered data. This limit
* is applied because writev() could fail with EINVAL otherwise
* which would simply add more unnecessary complexity.
*/
iovec_t *
pmsg_slist_to_iovec(slist_t *slist, int *iovcnt_ptr, size_t *size_ptr)
{
iovec_t *iov;
size_t held = 0;
int n;
g_assert(slist);
n = slist_length(slist);
if (n > 0) {
slist_iter_t *iter;
int i;
n = MIN(n, MAX_IOV_COUNT);
iov = halloc(n * sizeof *iov);
iter = slist_iter_before_head(slist);
for (i = 0; i < n; i++) {
pmsg_t *mb;
size_t size;
mb = slist_iter_next(iter);
pmsg_check_consistency(mb);
size = pmsg_size(mb);
g_assert(size > 0);
held += size;
iovec_set(&iov[i], deconstify_pointer(pmsg_read_base(mb)), size);
}
slist_iter_free(&iter);
} else {
iov = NULL;
}
if (iovcnt_ptr) {
*iovcnt_ptr = MAX(0, n);
}
if (size_ptr) {
*size_ptr = held;
}
return iov;
}
/**
* Write data at the end of the message.
* The message must be the only reference to the underlying data.
*
* @returns amount of written data.
*/
int
pmsg_write(pmsg_t *mb, const void *data, int len)
{
pdata_t *arena;
int available, written;
pmsg_check_consistency(mb);
g_assert(pmsg_is_writable(mb)); /* Not shared, or would corrupt data */
arena = mb->m_data;
available = arena->d_end - mb->m_wptr;
g_assert(available >= 0); /* Data cannot go beyond end of arena */
written = len >= available ? available : len;
if (written != 0)
mb->m_wptr = mempcpy(mb->m_wptr, data, written);
return written;
}
/**
* Extended cloning of message, adds a free routine callback.
*/
pmsg_t *
pmsg_clone_extend(pmsg_t *mb, pmsg_free_t free_cb, void *arg)
{
pmsg_ext_t *nmb;
pmsg_check_consistency(mb);
WALLOC(nmb);
nmb->pmsg = *mb; /* Struct copy */
nmb->pmsg.magic = PMSG_EXT_MAGIC;
pdata_addref(nmb->pmsg.m_data);
nmb->pmsg.m_flags |= PMSG_PF_EXT;
nmb->pmsg.m_refcnt = 1;
nmb->m_free = free_cb;
nmb->m_arg = arg;
return cast_to_pmsg(nmb);
}
/**
* Returns the size of the data held in the buffer list.
*/
size_t
pmsg_slist_size(const slist_t *slist)
{
slist_iter_t *iter;
size_t size = 0;
g_assert(slist != NULL);
iter = slist_iter_before_head(slist);
while (slist_iter_has_next(iter)) {
const pmsg_t *mb;
mb = slist_iter_next(iter);
pmsg_check_consistency(mb);
size += pmsg_size(mb);
}
slist_iter_free(&iter);
return size;
}
/**
* Shift back unread data to the beginning of the buffer if that can make
* at least 1/nth of the total arena size available for writing.
*/
void
pmsg_fractional_compact(pmsg_t *mb, int n)
{
int shifting;
g_assert(n > 0);
pmsg_check_consistency(mb);
g_assert(pmsg_is_writable(mb)); /* Not shared, or would corrupt data */
g_assert(mb->m_rptr <= mb->m_wptr);
shifting = mb->m_rptr - mb->m_data->d_arena;
g_assert(shifting >= 0);
if (shifting != 0) {
unsigned available = pmsg_available(mb) + shifting;
if (available >= pmsg_phys_len(mb) / n) {
memmove(mb->m_data->d_arena, mb->m_rptr, pmsg_size(mb));
mb->m_rptr -= shifting;
mb->m_wptr -= shifting;
}
}
}
/**
* Free all message blocks, and decrease ref count on all data buffers.
*
* If the message block is referenced by more than one place, simply
* decrease its reference count. No freeing occurs and the free routine
* is therefore not invoked.
*/
void
pmsg_free(pmsg_t *mb)
{
pdata_t *db = mb->m_data;
pmsg_check_consistency(mb);
g_assert(mb->m_refcnt != 0);
/*
* Don't free anything if refcnt != 1.
*/
if (mb->m_refcnt > 1U) {
mb->m_refcnt--;
return;
}
/*
* Invoke free routine on extended message block.
*/
if (pmsg_is_extended(mb)) {
pmsg_ext_t *emb = cast_to_pmsg_ext(mb);
if (emb->m_free)
(*emb->m_free)(mb, emb->m_arg);
WFREE0(emb);
} else {
WFREE0(mb);
}
/*
* Unref buffer data only after possible free routine was
* invoked, since it may cause a free, preventing access to
* memory from within the free routine.
*/
pdata_unref(db);
}
/**
* Fill newly created message block.
*
* @return the message block given as argument.
*/
static pmsg_t *
pmsg_fill(pmsg_t *mb, pdata_t *db, int prio, bool ext, const void *buf, int len)
{
mb->magic = ext ? PMSG_EXT_MAGIC : PMSG_MAGIC;
mb->m_data = db;
mb->m_prio = prio;
mb->m_flags = ext ? PMSG_PF_EXT : 0;
mb->m_u.m_check = NULL;
mb->m_refcnt = 1;
db->d_refcnt++;
if (buf) {
mb->m_rptr = db->d_arena;
mb->m_wptr = db->d_arena + len;
memcpy(db->d_arena, buf, len);
} else
mb->m_rptr = mb->m_wptr = db->d_arena;
g_assert(implies(buf, len == pmsg_size(mb)));
pmsg_check_consistency(mb);
return mb;
}