924 lines
26 KiB
C++
924 lines
26 KiB
C++
/*
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* Copyright © 2007,2008,2009,2010 Red Hat, Inc.
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* Copyright © 2012,2018 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*
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* Red Hat Author(s): Behdad Esfahbod
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* Google Author(s): Behdad Esfahbod
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*/
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#ifndef HB_MACHINERY_HH
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#define HB_MACHINERY_HH
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#include "hb.hh"
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#include "hb-blob.hh"
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#include "hb-iter.hh"
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#include "hb-vector.hh"
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/*
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* Casts
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*/
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/* Cast to struct T, reference to reference */
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template<typename Type, typename TObject>
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static inline const Type& CastR(const TObject &X)
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{ return reinterpret_cast<const Type&> (X); }
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template<typename Type, typename TObject>
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static inline Type& CastR(TObject &X)
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{ return reinterpret_cast<Type&> (X); }
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/* Cast to struct T, pointer to pointer */
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template<typename Type, typename TObject>
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static inline const Type* CastP(const TObject *X)
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{ return reinterpret_cast<const Type*> (X); }
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template<typename Type, typename TObject>
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static inline Type* CastP(TObject *X)
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{ return reinterpret_cast<Type*> (X); }
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/* StructAtOffset<T>(P,Ofs) returns the struct T& that is placed at memory
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* location pointed to by P plus Ofs bytes. */
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template<typename Type>
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static inline const Type& StructAtOffset(const void *P, unsigned int offset)
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{ return * reinterpret_cast<const Type*> ((const char *) P + offset); }
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template<typename Type>
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static inline Type& StructAtOffset(void *P, unsigned int offset)
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{ return * reinterpret_cast<Type*> ((char *) P + offset); }
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/* StructAfter<T>(X) returns the struct T& that is placed after X.
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* Works with X of variable size also. X must implement get_size() */
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template<typename Type, typename TObject>
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static inline const Type& StructAfter(const TObject &X)
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{ return StructAtOffset<Type>(&X, X.get_size()); }
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template<typename Type, typename TObject>
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static inline Type& StructAfter(TObject &X)
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{ return StructAtOffset<Type>(&X, X.get_size()); }
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/*
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* Size checking
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*/
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/* Check _assertion in a method environment */
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#define _DEFINE_INSTANCE_ASSERTION1(_line, _assertion) \
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inline void _instance_assertion_on_line_##_line (void) const \
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{ static_assert ((_assertion), ""); } \
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static_assert (true, "") /* So we require semicolon here. */
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# define _DEFINE_INSTANCE_ASSERTION0(_line, _assertion) _DEFINE_INSTANCE_ASSERTION1 (_line, _assertion)
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# define DEFINE_INSTANCE_ASSERTION(_assertion) _DEFINE_INSTANCE_ASSERTION0 (__LINE__, _assertion)
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/* Check that _code compiles in a method environment */
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#define _DEFINE_COMPILES_ASSERTION1(_line, _code) \
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inline void _compiles_assertion_on_line_##_line (void) const \
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{ _code; }
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# define _DEFINE_COMPILES_ASSERTION0(_line, _code) _DEFINE_COMPILES_ASSERTION1 (_line, _code)
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# define DEFINE_COMPILES_ASSERTION(_code) _DEFINE_COMPILES_ASSERTION0 (__LINE__, _code)
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#define DEFINE_SIZE_STATIC(size) \
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DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size)); \
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inline unsigned int get_size (void) const { return (size); } \
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enum { static_size = (size) }; \
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enum { min_size = (size) }
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#define DEFINE_SIZE_UNION(size, _member) \
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DEFINE_INSTANCE_ASSERTION (0*sizeof(this->u._member.static_size) + sizeof(this->u._member) == (size)); \
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static const unsigned int min_size = (size)
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#define DEFINE_SIZE_MIN(size) \
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DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)); \
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static const unsigned int min_size = (size)
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#define DEFINE_SIZE_ARRAY(size, array) \
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DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + VAR * sizeof ((array)[0])); \
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DEFINE_COMPILES_ASSERTION ((void) (array)[0].static_size) \
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enum { min_size = (size) }
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#define DEFINE_SIZE_ARRAY_SIZED(size, array) \
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inline unsigned int get_size (void) const { return (size - (array).min_size + (array).get_size ()); } \
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DEFINE_SIZE_ARRAY(size, array)
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#define DEFINE_SIZE_ARRAY2(size, array1, array2) \
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DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + sizeof (this->array1[0]) + sizeof (this->array2[0])); \
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DEFINE_COMPILES_ASSERTION ((void) (array1)[0].static_size; (void) (array2)[0].static_size) \
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static const unsigned int min_size = (size)
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/*
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* Dispatch
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*/
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template <typename Context, typename Return, unsigned int MaxDebugDepth>
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struct hb_dispatch_context_t
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{
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enum { max_debug_depth = MaxDebugDepth };
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typedef Return return_t;
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template <typename T, typename F>
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inline bool may_dispatch (const T *obj HB_UNUSED, const F *format HB_UNUSED) { return true; }
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static return_t no_dispatch_return_value (void) { return Context::default_return_value (); }
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};
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/*
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* Sanitize
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*
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*
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* === Introduction ===
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*
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* The sanitize machinery is at the core of our zero-cost font loading. We
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* mmap() font file into memory and create a blob out of it. Font subtables
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* are returned as a readonly sub-blob of the main font blob. These table
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* blobs are then sanitized before use, to ensure invalid memory access does
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* not happen. The toplevel sanitize API use is like, eg. to load the 'head'
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* table:
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*
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* hb_blob_t *head_blob = hb_sanitize_context_t ().reference_table<OT::head> (face);
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*
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* The blob then can be converted to a head table struct with:
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*
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* const head *head_table = head_blob->as<head> ();
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*
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* What the reference_table does is, to call hb_face_reference_table() to load
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* the table blob, sanitize it and return either the sanitized blob, or empty
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* blob if sanitization failed. The blob->as() function returns the null
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* object of its template type argument if the blob is empty. Otherwise, it
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* just casts the blob contents to the desired type.
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*
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* Sanitizing a blob of data with a type T works as follows (with minor
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* simplification):
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*
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* - Cast blob content to T*, call sanitize() method of it,
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* - If sanitize succeeded, return blob.
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* - Otherwise, if blob is not writable, try making it writable,
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* or copy if cannot be made writable in-place,
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* - Call sanitize() again. Return blob if sanitize succeeded.
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* - Return empty blob otherwise.
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*
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*
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* === The sanitize() contract ===
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*
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* The sanitize() method of each object type shall return true if it's safe to
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* call other methods of the object, and false otherwise.
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*
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* Note that what sanitize() checks for might align with what the specification
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* describes as valid table data, but does not have to be. In particular, we
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* do NOT want to be pedantic and concern ourselves with validity checks that
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* are irrelevant to our use of the table. On the contrary, we want to be
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* lenient with error handling and accept invalid data to the extent that it
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* does not impose extra burden on us.
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*
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* Based on the sanitize contract, one can see that what we check for depends
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* on how we use the data in other table methods. Ie. if other table methods
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* assume that offsets do NOT point out of the table data block, then that's
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* something sanitize() must check for (GSUB/GPOS/GDEF/etc work this way). On
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* the other hand, if other methods do such checks themselves, then sanitize()
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* does not have to bother with them (glyf/local work this way). The choice
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* depends on the table structure and sanitize() performance. For example, to
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* check glyf/loca offsets in sanitize() would cost O(num-glyphs). We try hard
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* to avoid such costs during font loading. By postponing such checks to the
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* actual glyph loading, we reduce the sanitize cost to O(1) and total runtime
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* cost to O(used-glyphs). As such, this is preferred.
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*
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* The same argument can be made re GSUB/GPOS/GDEF, but there, the table
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* structure is so complicated that by checking all offsets at sanitize() time,
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* we make the code much simpler in other methods, as offsets and referenced
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* objects do not need to be validated at each use site.
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*/
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/* This limits sanitizing time on really broken fonts. */
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#ifndef HB_SANITIZE_MAX_EDITS
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#define HB_SANITIZE_MAX_EDITS 32
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#endif
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#ifndef HB_SANITIZE_MAX_OPS_FACTOR
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#define HB_SANITIZE_MAX_OPS_FACTOR 8
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#endif
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#ifndef HB_SANITIZE_MAX_OPS_MIN
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#define HB_SANITIZE_MAX_OPS_MIN 16384
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#endif
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#ifndef HB_SANITIZE_MAX_OPS_MAX
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#define HB_SANITIZE_MAX_OPS_MAX 0x3FFFFFFF
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#endif
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struct hb_sanitize_context_t :
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hb_dispatch_context_t<hb_sanitize_context_t, bool, HB_DEBUG_SANITIZE>
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{
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inline hb_sanitize_context_t (void) :
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debug_depth (0),
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start (nullptr), end (nullptr),
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max_ops (0),
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writable (false), edit_count (0),
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blob (nullptr),
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num_glyphs (65536),
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num_glyphs_set (false) {}
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inline const char *get_name (void) { return "SANITIZE"; }
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template <typename T, typename F>
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inline bool may_dispatch (const T *obj HB_UNUSED, const F *format)
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{ return format->sanitize (this); }
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template <typename T>
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inline return_t dispatch (const T &obj) { return obj.sanitize (this); }
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static return_t default_return_value (void) { return true; }
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static return_t no_dispatch_return_value (void) { return false; }
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bool stop_sublookup_iteration (const return_t r) const { return !r; }
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inline void init (hb_blob_t *b)
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{
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this->blob = hb_blob_reference (b);
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this->writable = false;
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}
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inline void set_num_glyphs (unsigned int num_glyphs_)
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{
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num_glyphs = num_glyphs_;
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num_glyphs_set = true;
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}
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inline unsigned int get_num_glyphs (void) { return num_glyphs; }
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inline void set_max_ops (int max_ops_) { max_ops = max_ops_; }
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/* TODO
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* This set_object() thing is to use sanitize at runtime lookup
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* application time. This is very distinct from the regular
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* sanitizer operation, so, eventually, separate into another
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* type and make hb_aat_apply_context_t use that one instead
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* of abusing this one.
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*/
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template <typename T>
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inline void set_object (const T& obj)
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{
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this->start = (const char *) &obj;
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this->end = (const char *) &obj + obj.get_size ();
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assert (this->start <= this->end); /* Must not overflow. */
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}
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inline void start_processing (void)
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{
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this->start = this->blob->data;
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this->end = this->start + this->blob->length;
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assert (this->start <= this->end); /* Must not overflow. */
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this->max_ops = MAX ((unsigned int) (this->end - this->start) * HB_SANITIZE_MAX_OPS_FACTOR,
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(unsigned) HB_SANITIZE_MAX_OPS_MIN);
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this->edit_count = 0;
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this->debug_depth = 0;
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DEBUG_MSG_LEVEL (SANITIZE, start, 0, +1,
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"start [%p..%p] (%lu bytes)",
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this->start, this->end,
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(unsigned long) (this->end - this->start));
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}
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inline void end_processing (void)
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{
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DEBUG_MSG_LEVEL (SANITIZE, this->start, 0, -1,
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"end [%p..%p] %u edit requests",
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this->start, this->end, this->edit_count);
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hb_blob_destroy (this->blob);
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this->blob = nullptr;
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this->start = this->end = nullptr;
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}
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inline bool check_range (const void *base, unsigned int len) const
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{
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const char *p = (const char *) base;
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bool ok = this->start <= p &&
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p <= this->end &&
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(unsigned int) (this->end - p) >= len &&
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this->max_ops-- > 0;
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DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0,
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"check_range [%p..%p] (%d bytes) in [%p..%p] -> %s",
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p, p + len, len,
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this->start, this->end,
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ok ? "OK" : "OUT-OF-RANGE");
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return likely (ok);
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}
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template <typename T>
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inline bool check_array (const T *base, unsigned int len, unsigned int record_size = T::static_size) const
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{
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const char *p = (const char *) base;
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bool overflows = hb_unsigned_mul_overflows (len, record_size);
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unsigned int array_size = record_size * len;
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bool ok = !overflows && this->check_range (base, array_size);
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DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0,
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"check_array [%p..%p] (%d*%d=%d bytes) in [%p..%p] -> %s",
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p, p + (record_size * len), record_size, len, (unsigned int) array_size,
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this->start, this->end,
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overflows ? "OVERFLOWS" : ok ? "OK" : "OUT-OF-RANGE");
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return likely (ok);
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}
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template <typename Type>
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inline bool check_struct (const Type *obj) const
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{
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return likely (this->check_range (obj, obj->min_size));
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}
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inline bool may_edit (const void *base, unsigned int len)
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{
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if (this->edit_count >= HB_SANITIZE_MAX_EDITS)
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return false;
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const char *p = (const char *) base;
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this->edit_count++;
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DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0,
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"may_edit(%u) [%p..%p] (%d bytes) in [%p..%p] -> %s",
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this->edit_count,
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p, p + len, len,
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this->start, this->end,
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this->writable ? "GRANTED" : "DENIED");
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return this->writable;
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}
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template <typename Type, typename ValueType>
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inline bool try_set (const Type *obj, const ValueType &v) {
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if (this->may_edit (obj, obj->static_size)) {
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const_cast<Type *> (obj)->set (v);
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return true;
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}
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return false;
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}
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template <typename Type>
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inline hb_blob_t *sanitize_blob (hb_blob_t *blob)
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{
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bool sane;
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init (blob);
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retry:
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DEBUG_MSG_FUNC (SANITIZE, start, "start");
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start_processing ();
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if (unlikely (!start))
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{
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end_processing ();
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return blob;
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}
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Type *t = CastP<Type> (const_cast<char *> (start));
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sane = t->sanitize (this);
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if (sane)
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{
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if (edit_count)
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{
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DEBUG_MSG_FUNC (SANITIZE, start, "passed first round with %d edits; going for second round", edit_count);
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/* sanitize again to ensure no toe-stepping */
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edit_count = 0;
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sane = t->sanitize (this);
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if (edit_count) {
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DEBUG_MSG_FUNC (SANITIZE, start, "requested %d edits in second round; FAILLING", edit_count);
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sane = false;
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}
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}
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}
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else
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{
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if (edit_count && !writable) {
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start = hb_blob_get_data_writable (blob, nullptr);
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end = start + blob->length;
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if (start)
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{
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writable = true;
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/* ok, we made it writable by relocating. try again */
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DEBUG_MSG_FUNC (SANITIZE, start, "retry");
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goto retry;
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}
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}
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}
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end_processing ();
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DEBUG_MSG_FUNC (SANITIZE, start, sane ? "PASSED" : "FAILED");
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if (sane)
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{
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hb_blob_make_immutable (blob);
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return blob;
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}
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else
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{
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hb_blob_destroy (blob);
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return hb_blob_get_empty ();
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}
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}
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template <typename Type>
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inline hb_blob_t *reference_table (const hb_face_t *face, hb_tag_t tableTag = Type::tableTag)
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{
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if (!num_glyphs_set)
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set_num_glyphs (hb_face_get_glyph_count (face));
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return sanitize_blob<Type> (hb_face_reference_table (face, tableTag));
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}
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mutable unsigned int debug_depth;
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const char *start, *end;
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mutable int max_ops;
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private:
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bool writable;
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unsigned int edit_count;
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hb_blob_t *blob;
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unsigned int num_glyphs;
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bool num_glyphs_set;
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};
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/*
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* Serialize
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*/
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struct hb_serialize_context_t
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{
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inline hb_serialize_context_t (void *start_, unsigned int size)
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{
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this->start = (char *) start_;
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this->end = this->start + size;
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reset ();
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}
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inline void reset (void)
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{
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this->ran_out_of_room = false;
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this->head = this->start;
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this->debug_depth = 0;
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}
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inline bool err (bool e) { return this->ran_out_of_room = this->ran_out_of_room || e; }
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/* To be called around main operation. */
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|
template <typename Type>
|
|
inline Type *start_serialize (void)
|
|
{
|
|
DEBUG_MSG_LEVEL (SERIALIZE, this->start, 0, +1,
|
|
"start [%p..%p] (%lu bytes)",
|
|
this->start, this->end,
|
|
(unsigned long) (this->end - this->start));
|
|
|
|
return start_embed<Type> ();
|
|
}
|
|
inline void end_serialize (void)
|
|
{
|
|
DEBUG_MSG_LEVEL (SERIALIZE, this->start, 0, -1,
|
|
"end [%p..%p] serialized %d bytes; %s",
|
|
this->start, this->end,
|
|
(int) (this->head - this->start),
|
|
this->ran_out_of_room ? "RAN OUT OF ROOM" : "did not ran out of room");
|
|
}
|
|
|
|
inline unsigned int length (void) const { return this->head - this->start; }
|
|
|
|
inline void align (unsigned int alignment)
|
|
{
|
|
unsigned int l = length () % alignment;
|
|
if (l)
|
|
allocate_size<void> (alignment - l);
|
|
}
|
|
|
|
template <typename Type>
|
|
inline Type *start_embed (void) const
|
|
{
|
|
Type *ret = reinterpret_cast<Type *> (this->head);
|
|
return ret;
|
|
}
|
|
|
|
template <typename Type>
|
|
inline Type *allocate_size (unsigned int size)
|
|
{
|
|
if (unlikely (this->ran_out_of_room || this->end - this->head < ptrdiff_t (size))) {
|
|
this->ran_out_of_room = true;
|
|
return nullptr;
|
|
}
|
|
memset (this->head, 0, size);
|
|
char *ret = this->head;
|
|
this->head += size;
|
|
return reinterpret_cast<Type *> (ret);
|
|
}
|
|
|
|
template <typename Type>
|
|
inline Type *allocate_min (void)
|
|
{
|
|
return this->allocate_size<Type> (Type::min_size);
|
|
}
|
|
|
|
template <typename Type>
|
|
inline 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>
|
|
inline Type *extend_min (Type &obj)
|
|
{
|
|
unsigned int size = obj.min_size;
|
|
assert (this->start <= (char *) &obj && (char *) &obj <= this->head && (char *) &obj + size >= this->head);
|
|
if (unlikely (!this->allocate_size<Type> (((char *) &obj) + size - this->head))) return nullptr;
|
|
return reinterpret_cast<Type *> (&obj);
|
|
}
|
|
|
|
template <typename Type>
|
|
inline Type *extend (Type &obj)
|
|
{
|
|
unsigned int size = obj.get_size ();
|
|
assert (this->start < (char *) &obj && (char *) &obj <= this->head && (char *) &obj + size >= this->head);
|
|
if (unlikely (!this->allocate_size<Type> (((char *) &obj) + size - this->head))) return nullptr;
|
|
return reinterpret_cast<Type *> (&obj);
|
|
}
|
|
|
|
/* Output routines. */
|
|
template <typename Type>
|
|
inline Type *copy (void) const
|
|
{
|
|
assert (!this->ran_out_of_room);
|
|
unsigned int len = this->head - this->start;
|
|
void *p = malloc (len);
|
|
if (p)
|
|
memcpy (p, this->start, len);
|
|
return reinterpret_cast<Type *> (p);
|
|
}
|
|
inline hb_bytes_t copy_bytes (void) const
|
|
{
|
|
assert (!this->ran_out_of_room);
|
|
unsigned int len = this->head - this->start;
|
|
void *p = malloc (len);
|
|
if (p)
|
|
memcpy (p, this->start, len);
|
|
else
|
|
return hb_bytes_t ();
|
|
return hb_bytes_t (p, len);
|
|
}
|
|
inline hb_blob_t *copy_blob (void) const
|
|
{
|
|
assert (!this->ran_out_of_room);
|
|
return hb_blob_create (this->start,
|
|
this->head - this->start,
|
|
HB_MEMORY_MODE_DUPLICATE,
|
|
nullptr, nullptr);
|
|
}
|
|
|
|
public:
|
|
unsigned int debug_depth;
|
|
char *start, *end, *head;
|
|
bool ran_out_of_room;
|
|
};
|
|
|
|
|
|
/*
|
|
* Supplier
|
|
*/
|
|
|
|
template <typename Type>
|
|
struct Supplier
|
|
{
|
|
inline Supplier (const Type *array, unsigned int len_, unsigned int stride_=sizeof (Type))
|
|
{
|
|
head = array;
|
|
len = len_;
|
|
stride = stride_;
|
|
}
|
|
inline Supplier (const hb_vector_t<Type> *v)
|
|
{
|
|
head = *v;
|
|
len = v->len;
|
|
stride = sizeof (Type);
|
|
}
|
|
|
|
inline const Type operator [] (unsigned int i) const
|
|
{
|
|
if (unlikely (i >= len)) return Type ();
|
|
return * (const Type *) (const void *) ((const char *) head + stride * i);
|
|
}
|
|
|
|
inline Supplier<Type> & operator += (unsigned int count)
|
|
{
|
|
if (unlikely (count > len))
|
|
count = len;
|
|
len -= count;
|
|
head = (const Type *) (const void *) ((const char *) head + stride * count);
|
|
return *this;
|
|
}
|
|
|
|
private:
|
|
inline Supplier (const Supplier<Type> &); /* Disallow copy */
|
|
inline Supplier<Type>& operator= (const Supplier<Type> &); /* Disallow copy */
|
|
|
|
unsigned int len;
|
|
unsigned int stride;
|
|
const Type *head;
|
|
};
|
|
|
|
|
|
/*
|
|
* Big-endian integers.
|
|
*/
|
|
|
|
template <typename Type, int Bytes> struct BEInt;
|
|
|
|
template <typename Type>
|
|
struct BEInt<Type, 1>
|
|
{
|
|
public:
|
|
typedef Type type;
|
|
inline void set (Type V)
|
|
{
|
|
v = V;
|
|
}
|
|
inline operator Type (void) const
|
|
{
|
|
return v;
|
|
}
|
|
private: uint8_t v;
|
|
};
|
|
template <typename Type>
|
|
struct BEInt<Type, 2>
|
|
{
|
|
public:
|
|
typedef Type type;
|
|
inline void set (Type V)
|
|
{
|
|
v[0] = (V >> 8) & 0xFF;
|
|
v[1] = (V ) & 0xFF;
|
|
}
|
|
inline operator Type (void) const
|
|
{
|
|
return (v[0] << 8)
|
|
+ (v[1] );
|
|
}
|
|
private: uint8_t v[2];
|
|
};
|
|
template <typename Type>
|
|
struct BEInt<Type, 3>
|
|
{
|
|
public:
|
|
typedef Type type;
|
|
inline void set (Type V)
|
|
{
|
|
v[0] = (V >> 16) & 0xFF;
|
|
v[1] = (V >> 8) & 0xFF;
|
|
v[2] = (V ) & 0xFF;
|
|
}
|
|
inline operator Type (void) const
|
|
{
|
|
return (v[0] << 16)
|
|
+ (v[1] << 8)
|
|
+ (v[2] );
|
|
}
|
|
private: uint8_t v[3];
|
|
};
|
|
template <typename Type>
|
|
struct BEInt<Type, 4>
|
|
{
|
|
public:
|
|
typedef Type type;
|
|
inline void set (Type V)
|
|
{
|
|
v[0] = (V >> 24) & 0xFF;
|
|
v[1] = (V >> 16) & 0xFF;
|
|
v[2] = (V >> 8) & 0xFF;
|
|
v[3] = (V ) & 0xFF;
|
|
}
|
|
inline operator Type (void) const
|
|
{
|
|
return (v[0] << 24)
|
|
+ (v[1] << 16)
|
|
+ (v[2] << 8)
|
|
+ (v[3] );
|
|
}
|
|
private: uint8_t v[4];
|
|
};
|
|
|
|
|
|
/*
|
|
* Lazy loaders.
|
|
*/
|
|
|
|
template <typename Data, unsigned int WheresData>
|
|
struct hb_data_wrapper_t
|
|
{
|
|
static_assert (WheresData > 0, "");
|
|
|
|
inline Data * get_data (void) const
|
|
{
|
|
return *(((Data **) (void *) this) - WheresData);
|
|
}
|
|
|
|
template <typename Stored, typename Subclass>
|
|
inline Stored * call_create (void) const
|
|
{
|
|
Data *data = this->get_data ();
|
|
return likely (data) ? Subclass::create (data) : nullptr;
|
|
}
|
|
};
|
|
template <>
|
|
struct hb_data_wrapper_t<void, 0>
|
|
{
|
|
template <typename Stored, typename Funcs>
|
|
inline Stored * call_create (void) const
|
|
{
|
|
return Funcs::create ();
|
|
}
|
|
};
|
|
|
|
template <typename T1, typename T2> struct hb_non_void_t { typedef T1 value; };
|
|
template <typename T2> struct hb_non_void_t<void, T2> { typedef T2 value; };
|
|
|
|
template <typename Returned,
|
|
typename Subclass = void,
|
|
typename Data = void,
|
|
unsigned int WheresData = 0,
|
|
typename Stored = Returned>
|
|
struct hb_lazy_loader_t : hb_data_wrapper_t<Data, WheresData>
|
|
{
|
|
typedef typename hb_non_void_t<Subclass,
|
|
hb_lazy_loader_t<Returned,Subclass,Data,WheresData,Stored>
|
|
>::value Funcs;
|
|
|
|
inline void init0 (void) {} /* Init, when memory is already set to 0. No-op for us. */
|
|
inline void init (void) { instance.set_relaxed (nullptr); }
|
|
inline void fini (void)
|
|
{
|
|
do_destroy (instance.get ());
|
|
}
|
|
inline void free_instance (void)
|
|
{
|
|
retry:
|
|
Stored *p = instance.get ();
|
|
if (unlikely (p && !this->instance.cmpexch (p, nullptr)))
|
|
goto retry;
|
|
do_destroy (p);
|
|
}
|
|
|
|
static inline void do_destroy (Stored *p)
|
|
{
|
|
if (p)
|
|
Funcs::destroy (p);
|
|
}
|
|
|
|
inline const Returned * operator -> (void) const { return get (); }
|
|
inline const Returned & operator * (void) const { return *get (); }
|
|
template <typename C> inline operator const C * (void) const { return get (); }
|
|
|
|
inline Stored * get_stored (void) const
|
|
{
|
|
retry:
|
|
Stored *p = this->instance.get ();
|
|
if (unlikely (!p))
|
|
{
|
|
p = this->template call_create<Stored, Funcs> ();
|
|
if (unlikely (!p))
|
|
return const_cast<Stored *> (Funcs::get_null ());
|
|
|
|
if (unlikely (!this->instance.cmpexch (nullptr, p)))
|
|
{
|
|
do_destroy (p);
|
|
goto retry;
|
|
}
|
|
}
|
|
return p;
|
|
}
|
|
inline Stored * get_stored_relaxed (void) const
|
|
{
|
|
return this->instance.get_relaxed ();
|
|
}
|
|
|
|
inline void set_stored (Stored *instance_)
|
|
{
|
|
/* This *must* be called when there are no other threads accessing.
|
|
* However, to make TSan, etc, happy, we using cmpexch. */
|
|
retry:
|
|
Stored *p = this->instance.get ();
|
|
if (unlikely (!this->instance.cmpexch (p, instance_)))
|
|
goto retry;
|
|
do_destroy (p);
|
|
}
|
|
|
|
inline const Returned * get (void) const { return Funcs::convert (get_stored ()); }
|
|
inline const Returned * get_relaxed (void) const { return Funcs::convert (get_stored_relaxed ()); }
|
|
inline Returned * get_unconst (void) const { return const_cast<Returned *> (Funcs::convert (get_stored ())); }
|
|
|
|
/* To be possibly overloaded by subclasses. */
|
|
static inline Returned* convert (Stored *p) { return p; }
|
|
|
|
/* By default null/init/fini the object. */
|
|
static inline const Stored* get_null (void) { return &Null(Stored); }
|
|
static inline Stored *create (Data *data)
|
|
{
|
|
Stored *p = (Stored *) calloc (1, sizeof (Stored));
|
|
if (likely (p))
|
|
p->init (data);
|
|
return p;
|
|
}
|
|
static inline Stored *create (void)
|
|
{
|
|
Stored *p = (Stored *) calloc (1, sizeof (Stored));
|
|
if (likely (p))
|
|
p->init ();
|
|
return p;
|
|
}
|
|
static inline void destroy (Stored *p)
|
|
{
|
|
p->fini ();
|
|
free (p);
|
|
}
|
|
|
|
private:
|
|
/* Must only have one pointer. */
|
|
hb_atomic_ptr_t<Stored *> instance;
|
|
};
|
|
|
|
/* Specializations. */
|
|
|
|
template <typename T, unsigned int WheresFace>
|
|
struct hb_face_lazy_loader_t : hb_lazy_loader_t<T,
|
|
hb_face_lazy_loader_t<T, WheresFace>,
|
|
hb_face_t, WheresFace> {};
|
|
|
|
template <typename T, unsigned int WheresFace>
|
|
struct hb_table_lazy_loader_t : hb_lazy_loader_t<T,
|
|
hb_table_lazy_loader_t<T, WheresFace>,
|
|
hb_face_t, WheresFace,
|
|
hb_blob_t>
|
|
{
|
|
static inline hb_blob_t *create (hb_face_t *face)
|
|
{
|
|
return hb_sanitize_context_t ().reference_table<T> (face);
|
|
}
|
|
static inline void destroy (hb_blob_t *p)
|
|
{
|
|
hb_blob_destroy (p);
|
|
}
|
|
static inline const hb_blob_t *get_null (void)
|
|
{
|
|
return hb_blob_get_empty ();
|
|
}
|
|
static inline const T* convert (const hb_blob_t *blob)
|
|
{
|
|
return blob->as<T> ();
|
|
}
|
|
|
|
inline hb_blob_t* get_blob (void) const
|
|
{
|
|
return this->get_stored ();
|
|
}
|
|
};
|
|
|
|
template <typename Subclass>
|
|
struct hb_font_funcs_lazy_loader_t : hb_lazy_loader_t<hb_font_funcs_t, Subclass>
|
|
{
|
|
static inline void destroy (hb_font_funcs_t *p)
|
|
{
|
|
hb_font_funcs_destroy (p);
|
|
}
|
|
static inline const hb_font_funcs_t *get_null (void)
|
|
{
|
|
return hb_font_funcs_get_empty ();
|
|
}
|
|
};
|
|
template <typename Subclass>
|
|
struct hb_unicode_funcs_lazy_loader_t : hb_lazy_loader_t<hb_unicode_funcs_t, Subclass>
|
|
{
|
|
static inline void destroy (hb_unicode_funcs_t *p)
|
|
{
|
|
hb_unicode_funcs_destroy (p);
|
|
}
|
|
static inline const hb_unicode_funcs_t *get_null (void)
|
|
{
|
|
return hb_unicode_funcs_get_empty ();
|
|
}
|
|
};
|
|
|
|
|
|
#endif /* HB_MACHINERY_HH */
|