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/*
* Copyright © 2007,2008,2009,2010 Red Hat, Inc.
* Copyright © 2012,2018 Google, Inc.
* Copyright © 2019 Facebook, Inc.
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Red Hat Author(s): Behdad Esfahbod
* Google Author(s): Behdad Esfahbod
* Facebook Author(s): Behdad Esfahbod
*/
#ifndef HB_SERIALIZE_HH
#define HB_SERIALIZE_HH
#include "hb.hh"
#include "hb-blob.hh"
#include "hb-map.hh"
#include "hb-pool.hh"
#ifdef HB_EXPERIMENTAL_API
#include "hb-subset-repacker.h"
#endif
/*
* Serialize
*/
enum hb_serialize_error_t {
HB_SERIALIZE_ERROR_NONE = 0x00000000u,
HB_SERIALIZE_ERROR_OTHER = 0x00000001u,
HB_SERIALIZE_ERROR_OFFSET_OVERFLOW = 0x00000002u,
HB_SERIALIZE_ERROR_OUT_OF_ROOM = 0x00000004u,
HB_SERIALIZE_ERROR_INT_OVERFLOW = 0x00000008u,
HB_SERIALIZE_ERROR_ARRAY_OVERFLOW = 0x00000010u
};
HB_MARK_AS_FLAG_T (hb_serialize_error_t);
struct hb_serialize_context_t
{
typedef unsigned objidx_t;
enum whence_t {
Head, /* Relative to the current object head (default). */
Tail, /* Relative to the current object tail after packed. */
Absolute /* Absolute: from the start of the serialize buffer. */
};
struct object_t
{
void fini () {
real_links.fini ();
virtual_links.fini ();
}
object_t () = default;
#ifdef HB_EXPERIMENTAL_API
object_t (const hb_object_t &o)
{
head = o.head;
tail = o.tail;
next = nullptr;
real_links.alloc (o.num_real_links);
for (unsigned i = 0 ; i < o.num_real_links; i++)
real_links.push (o.real_links[i]);
virtual_links.alloc (o.num_virtual_links);
for (unsigned i = 0; i < o.num_virtual_links; i++)
virtual_links.push (o.virtual_links[i]);
}
#endif
friend void swap (object_t& a, object_t& b)
{
hb_swap (a.head, b.head);
hb_swap (a.tail, b.tail);
hb_swap (a.next, b.next);
hb_swap (a.real_links, b.real_links);
hb_swap (a.virtual_links, b.virtual_links);
}
bool operator == (const object_t &o) const
{
// Virtual links aren't considered for equality since they don't affect the functionality
// of the object.
return (tail - head == o.tail - o.head)
&& (real_links.length == o.real_links.length)
&& 0 == hb_memcmp (head, o.head, tail - head)
&& real_links.as_bytes () == o.real_links.as_bytes ();
}
uint32_t hash () const
{
// Virtual links aren't considered for equality since they don't affect the functionality
// of the object.
return hb_bytes_t (head, tail - head).hash () ^
real_links.as_bytes ().hash ();
}
struct link_t
{
unsigned width: 3;
unsigned is_signed: 1;
unsigned whence: 2;
unsigned bias : 26;
unsigned position;
objidx_t objidx;
link_t () = default;
#ifdef HB_EXPERIMENTAL_API
link_t (const hb_link_t &o)
{
width = o.width;
is_signed = 0;
whence = 0;
position = o.position;
bias = 0;
objidx = o.objidx;
}
#endif
};
char *head;
char *tail;
hb_vector_t<link_t> real_links;
hb_vector_t<link_t> virtual_links;
object_t *next;
auto all_links () const HB_AUTO_RETURN
(( hb_concat (this->real_links, this->virtual_links) ));
auto all_links_writer () HB_AUTO_RETURN
(( hb_concat (this->real_links.writer (), this->virtual_links.writer ()) ));
};
struct snapshot_t
{
char *head;
char *tail;
object_t *current; // Just for sanity check
unsigned num_real_links;
unsigned num_virtual_links;
hb_serialize_error_t errors;
};
snapshot_t snapshot ()
{ return snapshot_t {
head, tail, current, current->real_links.length, current->virtual_links.length, errors }; }
hb_serialize_context_t (void *start_, unsigned int size) :
start ((char *) start_),
end (start + size),
current (nullptr)
{ reset (); }
~hb_serialize_context_t () { fini (); }
void fini ()
{
for (object_t *_ : ++hb_iter (packed)) _->fini ();
packed.fini ();
this->packed_map.fini ();
while (current)
{
auto *_ = current;
current = current->next;
_->fini ();
}
object_pool.fini ();
}
bool in_error () const { return bool (errors); }
bool successful () const { return !bool (errors); }
HB_NODISCARD bool ran_out_of_room () const { return errors & HB_SERIALIZE_ERROR_OUT_OF_ROOM; }
HB_NODISCARD bool offset_overflow () const { return errors & HB_SERIALIZE_ERROR_OFFSET_OVERFLOW; }
HB_NODISCARD bool only_offset_overflow () const { return errors == HB_SERIALIZE_ERROR_OFFSET_OVERFLOW; }
HB_NODISCARD bool only_overflow () const
{
return errors == HB_SERIALIZE_ERROR_OFFSET_OVERFLOW
|| errors == HB_SERIALIZE_ERROR_INT_OVERFLOW
|| errors == HB_SERIALIZE_ERROR_ARRAY_OVERFLOW;
}
void reset (void *start_, unsigned int size)
{
start = (char*) start_;
end = start + size;
reset ();
current = nullptr;
}
void reset ()
{
this->errors = HB_SERIALIZE_ERROR_NONE;
this->head = this->start;
this->tail = this->end;
this->debug_depth = 0;
fini ();
this->packed.push (nullptr);
this->packed_map.init ();
}
bool check_success (bool success,
hb_serialize_error_t err_type = HB_SERIALIZE_ERROR_OTHER)
{
return successful ()
&& (success || err (err_type));
}
template <typename T1, typename T2>
bool check_equal (T1 &&v1, T2 &&v2, hb_serialize_error_t err_type)
{
if ((long long) v1 != (long long) v2)
{
return err (err_type);
}
return true;
}
template <typename T1, typename T2>
bool check_assign (T1 &v1, T2 &&v2, hb_serialize_error_t err_type)
{ return check_equal (v1 = v2, v2, err_type); }
template <typename T> bool propagate_error (T &&obj)
{ return check_success (!hb_deref (obj).in_error ()); }
template <typename T1, typename... Ts> bool propagate_error (T1 &&o1, Ts&&... os)
{ return propagate_error (std::forward<T1> (o1)) &&
propagate_error (std::forward<Ts> (os)...); }
/* To be called around main operation. */
template <typename Type>
Type *start_serialize ()
{
DEBUG_MSG_LEVEL (SERIALIZE, this->start, 0, +1,
"start [%p..%p] (%lu bytes)",
this->start, this->end,
(unsigned long) (this->end - this->start));
assert (!current);
return push<Type> ();
}
void end_serialize ()
{
DEBUG_MSG_LEVEL (SERIALIZE, this->start, 0, -1,
"end [%p..%p] serialized %u bytes; %s",
this->start, this->end,
(unsigned) (this->head - this->start),
successful () ? "successful" : "UNSUCCESSFUL");
propagate_error (packed, packed_map);
if (unlikely (!current)) return;
if (unlikely (in_error()))
{
// Offset overflows that occur before link resolution cannot be handled
// by repacking, so set a more general error.
if (offset_overflow ()) err (HB_SERIALIZE_ERROR_OTHER);
return;
}
assert (!current->next);
/* Only "pack" if there exist other objects... Otherwise, don't bother.
* Saves a move. */
if (packed.length <= 1)
return;
pop_pack (false);
resolve_links ();
}
template <typename Type = void>
Type *push ()
{
if (unlikely (in_error ())) return start_embed<Type> ();
object_t *obj = object_pool.alloc ();
if (unlikely (!obj))
check_success (false);
else
{
obj->head = head;
obj->tail = tail;
obj->next = current;
current = obj;
}
return start_embed<Type> ();
}
void pop_discard ()
{
object_t *obj = current;
if (unlikely (!obj)) return;
if (unlikely (in_error())) return;
current = current->next;
revert (obj->head, obj->tail);
obj->fini ();
object_pool.release (obj);
}
/* Set share to false when an object is unlikely shareable with others
* so not worth an attempt, or a contiguous table is serialized as
* multiple consecutive objects in the reverse order so can't be shared.
*/
objidx_t pop_pack (bool share=true)
{
object_t *obj = current;
if (unlikely (!obj)) return 0;
if (unlikely (in_error())) return 0;
current = current->next;
obj->tail = head;
obj->next = nullptr;
unsigned len = obj->tail - obj->head;
head = obj->head; /* Rewind head. */
if (!len)
{
assert (!obj->real_links.length);
assert (!obj->virtual_links.length);
return 0;
}
objidx_t objidx;
if (share)
{
objidx = packed_map.get (obj);
if (objidx)
{
merge_virtual_links (obj, objidx);
obj->fini ();
return objidx;
}
}
tail -= len;
memmove (tail, obj->head, len);
obj->head = tail;
obj->tail = tail + len;
packed.push (obj);
if (unlikely (!propagate_error (packed)))
{
/* Obj wasn't successfully added to packed, so clean it up otherwise its
* links will be leaked. When we use constructor/destructors properly, we
* can remove these. */
obj->fini ();
return 0;
}
objidx = packed.length - 1;
if (share) packed_map.set (obj, objidx);
propagate_error (packed_map);
return objidx;
}
void revert (snapshot_t snap)
{
// Overflows that happened after the snapshot will be erased by the revert.
if (unlikely (in_error () && !only_overflow ())) return;
assert (snap.current == current);
current->real_links.shrink (snap.num_real_links);
current->virtual_links.shrink (snap.num_virtual_links);
errors = snap.errors;
revert (snap.head, snap.tail);
}
void revert (char *snap_head,
char *snap_tail)
{
if (unlikely (in_error ())) return;
assert (snap_head <= head);
assert (tail <= snap_tail);
head = snap_head;
tail = snap_tail;
discard_stale_objects ();
}
void discard_stale_objects ()
{
if (unlikely (in_error ())) return;
while (packed.length > 1 &&
packed.tail ()->head < tail)
{
packed_map.del (packed.tail ());
assert (!packed.tail ()->next);
packed.tail ()->fini ();
packed.pop ();
}
if (packed.length > 1)
assert (packed.tail ()->head == tail);
}
// Adds a virtual link from the current object to objidx. A virtual link is not associated with
// an actual offset field. They are solely used to enforce ordering constraints between objects.
// Adding a virtual link from object a to object b will ensure that object b is always packed after
// object a in the final serialized order.
//
// This is useful in certain situations where there needs to be a specific ordering in the
// final serialization. Such as when platform bugs require certain orderings, or to provide
// guidance to the repacker for better offset overflow resolution.
void add_virtual_link (objidx_t objidx)
{
if (unlikely (in_error ())) return;
if (!objidx)
return;
assert (current);
auto& link = *current->virtual_links.push ();
if (current->virtual_links.in_error ())
err (HB_SERIALIZE_ERROR_OTHER);
link.width = 0;
link.objidx = objidx;
link.is_signed = 0;
link.whence = 0;
link.position = 0;
link.bias = 0;
}
template <typename T>
void add_link (T &ofs, objidx_t objidx,
whence_t whence = Head,
unsigned bias = 0)
{
if (unlikely (in_error ())) return;
if (!objidx)
return;
assert (current);
assert (current->head <= (const char *) &ofs);
auto& link = *current->real_links.push ();
if (current->real_links.in_error ())
err (HB_SERIALIZE_ERROR_OTHER);
link.width = sizeof (T);
link.objidx = objidx;
if (unlikely (!sizeof (T)))
{
// This link is not associated with an actual offset and exists merely to enforce
// an ordering constraint.
link.is_signed = 0;
link.whence = 0;
link.position = 0;
link.bias = 0;
return;
}
link.is_signed = std::is_signed<hb_unwrap_type (T)>::value;
link.whence = (unsigned) whence;
link.position = (const char *) &ofs - current->head;
link.bias = bias;
}
unsigned to_bias (const void *base) const
{
if (unlikely (in_error ())) return 0;
if (!base) return 0;
assert (current);
assert (current->head <= (const char *) base);
return (const char *) base - current->head;
}
void resolve_links ()
{
if (unlikely (in_error ())) return;
assert (!current);
assert (packed.length > 1);
for (const object_t* parent : ++hb_iter (packed))
for (const object_t::link_t &link : parent->real_links)
{
const object_t* child = packed[link.objidx];
if (unlikely (!child)) { err (HB_SERIALIZE_ERROR_OTHER); return; }
unsigned offset = 0;
switch ((whence_t) link.whence) {
case Head: offset = child->head - parent->head; break;
case Tail: offset = child->head - parent->tail; break;
case Absolute: offset = (head - start) + (child->head - tail); break;
}
assert (offset >= link.bias);
offset -= link.bias;
if (link.is_signed)
{
assert (link.width == 2 || link.width == 4);
if (link.width == 4)
assign_offset<int32_t> (parent, link, offset);
else
assign_offset<int16_t> (parent, link, offset);
}
else
{
assert (link.width == 2 || link.width == 3 || link.width == 4);
if (link.width == 4)
assign_offset<uint32_t> (parent, link, offset);
else if (link.width == 3)
assign_offset<uint32_t, 3> (parent, link, offset);
else
assign_offset<uint16_t> (parent, link, offset);
}
}
}
unsigned int length () const
{
if (unlikely (!current)) return 0;
return this->head - current->head;
}
void align (unsigned int alignment)
{
unsigned int l = length () % alignment;
if (l)
allocate_size<void> (alignment - l);
}
template <typename Type = void>
Type *start_embed (const Type *obj HB_UNUSED = nullptr) const
{ return reinterpret_cast<Type *> (this->head); }
template <typename Type>
Type *start_embed (const Type &obj) const
{ return start_embed (std::addressof (obj)); }
bool err (hb_serialize_error_t err_type)
{
return !bool ((errors = (errors | err_type)));
}
template <typename Type>
Type *allocate_size (size_t size)
{
if (unlikely (in_error ())) return nullptr;
if (unlikely (size > INT_MAX || this->tail - this->head < ptrdiff_t (size)))
{
err (HB_SERIALIZE_ERROR_OUT_OF_ROOM);
return nullptr;
}
hb_memset (this->head, 0, size);
char *ret = this->head;
this->head += size;
return reinterpret_cast<Type *> (ret);
}
template <typename Type>
Type *allocate_min ()
{ return this->allocate_size<Type> (Type::min_size); }
template <typename Type>
Type *embed (const Type *obj)
{
unsigned int size = obj->get_size ();
Type *ret = this->allocate_size<Type> (size);
if (unlikely (!ret)) return nullptr;
memcpy (ret, obj, size);
return ret;
}
template <typename Type>
Type *embed (const Type &obj)
{ return embed (std::addressof (obj)); }
template <typename Type, typename ...Ts> auto
_copy (const Type &src, hb_priority<1>, Ts&&... ds) HB_RETURN
(Type *, src.copy (this, std::forward<Ts> (ds)...))
template <typename Type> auto
_copy (const Type &src, hb_priority<0>) -> decltype (&(hb_declval<Type> () = src))
{
Type *ret = this->allocate_size<Type> (sizeof (Type));
if (unlikely (!ret)) return nullptr;
*ret = src;
return ret;
}
/* Like embed, but active: calls obj.operator=() or obj.copy() to transfer data
* instead of memcpy(). */
template <typename Type, typename ...Ts>
Type *copy (const Type &src, Ts&&... ds)
{ return _copy (src, hb_prioritize, std::forward<Ts> (ds)...); }
template <typename Type, typename ...Ts>
Type *copy (const Type *src, Ts&&... ds)
{ return copy (*src, std::forward<Ts> (ds)...); }
template<typename Iterator,
hb_requires (hb_is_iterator (Iterator)),
typename ...Ts>
void copy_all (Iterator it, Ts&&... ds)
{ for (decltype (*it) _ : it) copy (_, std::forward<Ts> (ds)...); }
template <typename Type>
hb_serialize_context_t& operator << (const Type &obj) & { embed (obj); return *this; }
template <typename Type>
Type *extend_size (Type *obj, size_t size)
{
if (unlikely (in_error ())) return nullptr;
assert (this->start <= (char *) obj);
assert ((char *) obj <= this->head);
assert ((size_t) (this->head - (char *) obj) <= size);
if (unlikely (((char *) obj + size < (char *) obj) ||
!this->allocate_size<Type> (((char *) obj) + size - this->head))) return nullptr;
return reinterpret_cast<Type *> (obj);
}
template <typename Type>
Type *extend_size (Type &obj, size_t size)
{ return extend_size (std::addressof (obj), size); }
template <typename Type>
Type *extend_min (Type *obj) { return extend_size (obj, obj->min_size); }
template <typename Type>
Type *extend_min (Type &obj) { return extend_min (std::addressof (obj)); }
template <typename Type, typename ...Ts>
Type *extend (Type *obj, Ts&&... ds)
{ return extend_size (obj, obj->get_size (std::forward<Ts> (ds)...)); }
template <typename Type, typename ...Ts>
Type *extend (Type &obj, Ts&&... ds)
{ return extend (std::addressof (obj), std::forward<Ts> (ds)...); }
/* Output routines. */
hb_bytes_t copy_bytes () const
{
assert (successful ());
/* Copy both items from head side and tail side... */
unsigned int len = (this->head - this->start)
+ (this->end - this->tail);
// If len is zero don't hb_malloc as the memory won't get properly
// cleaned up later.
if (!len) return hb_bytes_t ();
char *p = (char *) hb_malloc (len);
if (unlikely (!p)) return hb_bytes_t ();
memcpy (p, this->start, this->head - this->start);
memcpy (p + (this->head - this->start), this->tail, this->end - this->tail);
return hb_bytes_t (p, len);
}
template <typename Type>
Type *copy () const
{ return reinterpret_cast<Type *> ((char *) copy_bytes ().arrayZ); }
hb_blob_t *copy_blob () const
{
hb_bytes_t b = copy_bytes ();
return hb_blob_create (b.arrayZ, b.length,
HB_MEMORY_MODE_WRITABLE,
(char *) b.arrayZ, hb_free);
}
const hb_vector_t<object_t *>& object_graph() const
{ return packed; }
private:
template <typename T, unsigned Size = sizeof (T)>
void assign_offset (const object_t* parent, const object_t::link_t &link, unsigned offset)
{
auto &off = * ((BEInt<T, Size> *) (parent->head + link.position));
assert (0 == off);
check_assign (off, offset, HB_SERIALIZE_ERROR_OFFSET_OVERFLOW);
}
public: /* TODO Make private. */
char *start, *head, *tail, *end;
unsigned int debug_depth;
hb_serialize_error_t errors;
private:
void merge_virtual_links (const object_t* from, objidx_t to_idx) {
object_t* to = packed[to_idx];
for (const auto& l : from->virtual_links) {
to->virtual_links.push (l);
}
}
/* Object memory pool. */
hb_pool_t<object_t> object_pool;
/* Stack of currently under construction objects. */
object_t *current;
/* Stack of packed objects. Object 0 is always nil object. */
hb_vector_t<object_t *> packed;
/* Map view of packed objects. */
hb_hashmap_t<const object_t *, objidx_t,
const object_t *, objidx_t,
nullptr, 0> packed_map;
};
#endif /* HB_SERIALIZE_HH */
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