/* * Copyright © 2007,2008,2009,2010 Red Hat, Inc. * Copyright © 2012,2018 Google, 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 */ #ifndef HB_MACHINERY_HH #define HB_MACHINERY_HH #include "hb.hh" #include "hb-blob.hh" #include "hb-array.hh" #include "hb-vector.hh" /* * Casts */ /* Cast to struct T, reference to reference */ template static inline const Type& CastR(const TObject &X) { return reinterpret_cast (X); } template static inline Type& CastR(TObject &X) { return reinterpret_cast (X); } /* Cast to struct T, pointer to pointer */ template static inline const Type* CastP(const TObject *X) { return reinterpret_cast (X); } template static inline Type* CastP(TObject *X) { return reinterpret_cast (X); } /* StructAtOffset(P,Ofs) returns the struct T& that is placed at memory * location pointed to by P plus Ofs bytes. */ template static inline const Type& StructAtOffset(const void *P, unsigned int offset) { return * reinterpret_cast ((const char *) P + offset); } template static inline Type& StructAtOffset(void *P, unsigned int offset) { return * reinterpret_cast ((char *) P + offset); } template static inline const Type& StructAtOffsetUnaligned(const void *P, unsigned int offset) { #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wcast-align" return * reinterpret_cast ((char *) P + offset); #pragma GCC diagnostic pop } template static inline Type& StructAtOffsetUnaligned(void *P, unsigned int offset) { #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wcast-align" return * reinterpret_cast ((char *) P + offset); #pragma GCC diagnostic pop } /* StructAfter(X) returns the struct T& that is placed after X. * Works with X of variable size also. X must implement get_size() */ template static inline const Type& StructAfter(const TObject &X) { return StructAtOffset(&X, X.get_size()); } template static inline Type& StructAfter(TObject &X) { return StructAtOffset(&X, X.get_size()); } /* * Size checking */ /* Check _assertion in a method environment */ #define _DEFINE_INSTANCE_ASSERTION1(_line, _assertion) \ void _instance_assertion_on_line_##_line () const \ { static_assert ((_assertion), ""); } # define _DEFINE_INSTANCE_ASSERTION0(_line, _assertion) _DEFINE_INSTANCE_ASSERTION1 (_line, _assertion) # define DEFINE_INSTANCE_ASSERTION(_assertion) _DEFINE_INSTANCE_ASSERTION0 (__LINE__, _assertion) /* Check that _code compiles in a method environment */ #define _DEFINE_COMPILES_ASSERTION1(_line, _code) \ void _compiles_assertion_on_line_##_line () const \ { _code; } # define _DEFINE_COMPILES_ASSERTION0(_line, _code) _DEFINE_COMPILES_ASSERTION1 (_line, _code) # define DEFINE_COMPILES_ASSERTION(_code) _DEFINE_COMPILES_ASSERTION0 (__LINE__, _code) #define DEFINE_SIZE_STATIC(size) \ DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size)) \ unsigned int get_size () const { return (size); } \ static constexpr unsigned null_size = (size); \ static constexpr unsigned min_size = (size); \ static constexpr unsigned static_size = (size) #define DEFINE_SIZE_UNION(size, _member) \ DEFINE_COMPILES_ASSERTION ((void) this->u._member.static_size) \ DEFINE_INSTANCE_ASSERTION (sizeof(this->u._member) == (size)) \ static constexpr unsigned null_size = (size); \ static constexpr unsigned min_size = (size) #define DEFINE_SIZE_MIN(size) \ DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \ static constexpr unsigned null_size = (size); \ static constexpr unsigned min_size = (size) #define DEFINE_SIZE_UNBOUNDED(size) \ DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \ static constexpr unsigned min_size = (size) #define DEFINE_SIZE_ARRAY(size, array) \ DEFINE_COMPILES_ASSERTION ((void) (array)[0].static_size) \ DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + VAR * sizeof ((array)[0])) \ static constexpr unsigned null_size = (size); \ static constexpr unsigned min_size = (size) #define DEFINE_SIZE_ARRAY_SIZED(size, array) \ unsigned int get_size () const { return (size - (array).min_size + (array).get_size ()); } \ DEFINE_SIZE_ARRAY(size, array) /* * Dispatch */ template struct hb_dispatch_context_t { static constexpr unsigned max_debug_depth = MaxDebugDepth; typedef Return return_t; template bool may_dispatch (const T *obj HB_UNUSED, const F *format HB_UNUSED) { return true; } static return_t no_dispatch_return_value () { return Context::default_return_value (); } static bool stop_sublookup_iteration (const return_t r HB_UNUSED) { return false; } }; /* * Sanitize * * * === Introduction === * * The sanitize machinery is at the core of our zero-cost font loading. We * mmap() font file into memory and create a blob out of it. Font subtables * are returned as a readonly sub-blob of the main font blob. These table * blobs are then sanitized before use, to ensure invalid memory access does * not happen. The toplevel sanitize API use is like, eg. to load the 'head' * table: * * hb_blob_t *head_blob = hb_sanitize_context_t ().reference_table (face); * * The blob then can be converted to a head table struct with: * * const head *head_table = head_blob->as (); * * What the reference_table does is, to call hb_face_reference_table() to load * the table blob, sanitize it and return either the sanitized blob, or empty * blob if sanitization failed. The blob->as() function returns the null * object of its template type argument if the blob is empty. Otherwise, it * just casts the blob contents to the desired type. * * Sanitizing a blob of data with a type T works as follows (with minor * simplification): * * - Cast blob content to T*, call sanitize() method of it, * - If sanitize succeeded, return blob. * - Otherwise, if blob is not writable, try making it writable, * or copy if cannot be made writable in-place, * - Call sanitize() again. Return blob if sanitize succeeded. * - Return empty blob otherwise. * * * === The sanitize() contract === * * The sanitize() method of each object type shall return true if it's safe to * call other methods of the object, and false otherwise. * * Note that what sanitize() checks for might align with what the specification * describes as valid table data, but does not have to be. In particular, we * do NOT want to be pedantic and concern ourselves with validity checks that * are irrelevant to our use of the table. On the contrary, we want to be * lenient with error handling and accept invalid data to the extent that it * does not impose extra burden on us. * * Based on the sanitize contract, one can see that what we check for depends * on how we use the data in other table methods. Ie. if other table methods * assume that offsets do NOT point out of the table data block, then that's * something sanitize() must check for (GSUB/GPOS/GDEF/etc work this way). On * the other hand, if other methods do such checks themselves, then sanitize() * does not have to bother with them (glyf/local work this way). The choice * depends on the table structure and sanitize() performance. For example, to * check glyf/loca offsets in sanitize() would cost O(num-glyphs). We try hard * to avoid such costs during font loading. By postponing such checks to the * actual glyph loading, we reduce the sanitize cost to O(1) and total runtime * cost to O(used-glyphs). As such, this is preferred. * * The same argument can be made re GSUB/GPOS/GDEF, but there, the table * structure is so complicated that by checking all offsets at sanitize() time, * we make the code much simpler in other methods, as offsets and referenced * objects do not need to be validated at each use site. */ /* This limits sanitizing time on really broken fonts. */ #ifndef HB_SANITIZE_MAX_EDITS #define HB_SANITIZE_MAX_EDITS 32 #endif #ifndef HB_SANITIZE_MAX_OPS_FACTOR #define HB_SANITIZE_MAX_OPS_FACTOR 8 #endif #ifndef HB_SANITIZE_MAX_OPS_MIN #define HB_SANITIZE_MAX_OPS_MIN 16384 #endif #ifndef HB_SANITIZE_MAX_OPS_MAX #define HB_SANITIZE_MAX_OPS_MAX 0x3FFFFFFF #endif struct hb_sanitize_context_t : hb_dispatch_context_t { hb_sanitize_context_t () : debug_depth (0), start (nullptr), end (nullptr), max_ops (0), writable (false), edit_count (0), blob (nullptr), num_glyphs (65536), num_glyphs_set (false) {} const char *get_name () { return "SANITIZE"; } template bool may_dispatch (const T *obj HB_UNUSED, const F *format) { return format->sanitize (this); } template return_t dispatch (const T &obj) { return obj.sanitize (this); } static return_t default_return_value () { return true; } static return_t no_dispatch_return_value () { return false; } bool stop_sublookup_iteration (const return_t r) const { return !r; } void init (hb_blob_t *b) { this->blob = hb_blob_reference (b); this->writable = false; } void set_num_glyphs (unsigned int num_glyphs_) { num_glyphs = num_glyphs_; num_glyphs_set = true; } unsigned int get_num_glyphs () { return num_glyphs; } void set_max_ops (int max_ops_) { max_ops = max_ops_; } template void set_object (const T *obj) { reset_object (); if (!obj) return; const char *obj_start = (const char *) obj; if (unlikely (obj_start < this->start || this->end <= obj_start)) this->start = this->end = nullptr; else { this->start = obj_start; this->end = obj_start + MIN (this->end - obj_start, obj->get_size ()); } } void reset_object () { this->start = this->blob->data; this->end = this->start + this->blob->length; assert (this->start <= this->end); /* Must not overflow. */ } void start_processing () { reset_object (); this->max_ops = MAX ((unsigned int) (this->end - this->start) * HB_SANITIZE_MAX_OPS_FACTOR, (unsigned) HB_SANITIZE_MAX_OPS_MIN); this->edit_count = 0; this->debug_depth = 0; DEBUG_MSG_LEVEL (SANITIZE, start, 0, +1, "start [%p..%p] (%lu bytes)", this->start, this->end, (unsigned long) (this->end - this->start)); } void end_processing () { DEBUG_MSG_LEVEL (SANITIZE, this->start, 0, -1, "end [%p..%p] %u edit requests", this->start, this->end, this->edit_count); hb_blob_destroy (this->blob); this->blob = nullptr; this->start = this->end = nullptr; } bool check_range (const void *base, unsigned int len) const { const char *p = (const char *) base; bool ok = this->start <= p && p <= this->end && (unsigned int) (this->end - p) >= len && this->max_ops-- > 0; DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0, "check_range [%p..%p] (%d bytes) in [%p..%p] -> %s", p, p + len, len, this->start, this->end, ok ? "OK" : "OUT-OF-RANGE"); return likely (ok); } template bool check_range (const T *base, unsigned int a, unsigned int b) const { return !hb_unsigned_mul_overflows (a, b) && this->check_range (base, a * b); } template bool check_range (const T *base, unsigned int a, unsigned int b, unsigned int c) const { return !hb_unsigned_mul_overflows (a, b) && this->check_range (base, a * b, c); } template bool check_array (const T *base, unsigned int len) const { return this->check_range (base, len, hb_static_size (T)); } template bool check_array (const T *base, unsigned int a, unsigned int b) const { return this->check_range (base, a, b, hb_static_size (T)); } template bool check_struct (const Type *obj) const { return likely (this->check_range (obj, obj->min_size)); } bool may_edit (const void *base, unsigned int len) { if (this->edit_count >= HB_SANITIZE_MAX_EDITS) return false; const char *p = (const char *) base; this->edit_count++; DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0, "may_edit(%u) [%p..%p] (%d bytes) in [%p..%p] -> %s", this->edit_count, p, p + len, len, this->start, this->end, this->writable ? "GRANTED" : "DENIED"); return this->writable; } template bool try_set (const Type *obj, const ValueType &v) { if (this->may_edit (obj, hb_static_size (Type))) { hb_assign (* const_cast (obj), v); return true; } return false; } template hb_blob_t *sanitize_blob (hb_blob_t *blob) { bool sane; init (blob); retry: DEBUG_MSG_FUNC (SANITIZE, start, "start"); start_processing (); if (unlikely (!start)) { end_processing (); return blob; } Type *t = CastP (const_cast (start)); sane = t->sanitize (this); if (sane) { if (edit_count) { DEBUG_MSG_FUNC (SANITIZE, start, "passed first round with %d edits; going for second round", edit_count); /* sanitize again to ensure no toe-stepping */ edit_count = 0; sane = t->sanitize (this); if (edit_count) { DEBUG_MSG_FUNC (SANITIZE, start, "requested %d edits in second round; FAILLING", edit_count); sane = false; } } } else { if (edit_count && !writable) { start = hb_blob_get_data_writable (blob, nullptr); end = start + blob->length; if (start) { writable = true; /* ok, we made it writable by relocating. try again */ DEBUG_MSG_FUNC (SANITIZE, start, "retry"); goto retry; } } } end_processing (); DEBUG_MSG_FUNC (SANITIZE, start, sane ? "PASSED" : "FAILED"); if (sane) { hb_blob_make_immutable (blob); return blob; } else { hb_blob_destroy (blob); return hb_blob_get_empty (); } } template hb_blob_t *reference_table (const hb_face_t *face, hb_tag_t tableTag = Type::tableTag) { if (!num_glyphs_set) set_num_glyphs (hb_face_get_glyph_count (face)); return sanitize_blob (hb_face_reference_table (face, tableTag)); } mutable unsigned int debug_depth; const char *start, *end; mutable int max_ops; private: bool writable; unsigned int edit_count; hb_blob_t *blob; unsigned int num_glyphs; bool num_glyphs_set; }; struct hb_sanitize_with_object_t { template hb_sanitize_with_object_t (hb_sanitize_context_t *c, const T& obj) : c (c) { c->set_object (obj); } ~hb_sanitize_with_object_t () { c->reset_object (); } private: hb_sanitize_context_t *c; }; /* * Serialize */ struct hb_serialize_context_t { hb_serialize_context_t (void *start_, unsigned int size) { this->start = (char *) start_; this->end = this->start + size; reset (); } bool in_error () const { return !this->successful; } void reset () { this->successful = true; this->head = this->start; this->debug_depth = 0; } bool propagate_error (bool e) { return this->successful = this->successful && e; } template bool propagate_error (const T &obj) { return this->successful = this->successful && !obj.in_error (); } template bool propagate_error (const T *obj) { return this->successful = this->successful && !obj->in_error (); } template bool propagate_error (T1 &o1, T2 &o2) { return propagate_error (o1) && propagate_error (o2); } template bool propagate_error (T1 *o1, T2 *o2) { return propagate_error (o1) && propagate_error (o2); } template bool propagate_error (T1 &o1, T2 &o2, T3 &o3) { return propagate_error (o1) && propagate_error (o2, o3); } template bool propagate_error (T1 *o1, T2 *o2, T3 *o3) { return propagate_error (o1) && propagate_error (o2, o3); } /* To be called around main operation. */ template 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)); return start_embed (); } void end_serialize () { 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->successful ? "successful" : "UNSUCCESSFUL"); } unsigned int length () const { return this->head - this->start; } void align (unsigned int alignment) { unsigned int l = length () % alignment; if (l) allocate_size (alignment - l); } template Type *start_embed (const Type *_ HB_UNUSED = nullptr) const { Type *ret = reinterpret_cast (this->head); return ret; } template Type *allocate_size (unsigned int size) { if (unlikely (!this->successful || this->end - this->head < ptrdiff_t (size))) { this->successful = false; return nullptr; } memset (this->head, 0, size); char *ret = this->head; this->head += size; return reinterpret_cast (ret); } template Type *allocate_min () { return this->allocate_size (Type::min_size); } template Type *embed (const Type &obj) { unsigned int size = obj.get_size (); Type *ret = this->allocate_size (size); if (unlikely (!ret)) return nullptr; memcpy (ret, &obj, size); return ret; } template hb_serialize_context_t &operator << (const Type &obj) { embed (obj); return *this; } template Type *extend_size (Type &obj, unsigned int size) { assert (this->start <= (char *) &obj); assert ((char *) &obj <= this->head); assert ((char *) &obj + size >= this->head); if (unlikely (!this->allocate_size (((char *) &obj) + size - this->head))) return nullptr; return reinterpret_cast (&obj); } template Type *extend_min (Type &obj) { return extend_size (obj, obj.min_size); } template Type *extend (Type &obj) { return extend_size (obj, obj.get_size ()); } /* Output routines. */ template Type *copy () const { assert (this->successful); unsigned int len = this->head - this->start; void *p = malloc (len); if (p) memcpy (p, this->start, len); return reinterpret_cast (p); } hb_bytes_t copy_bytes () const { assert (this->successful); 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 ((char *) p, len); } hb_blob_t *copy_blob () const { assert (this->successful); 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 successful; }; /* * Big-endian integers. */ template struct BEInt; template struct BEInt { public: void set (Type V) { v = V; } operator Type () const { return v; } private: uint8_t v; }; template struct BEInt { public: void set (Type V) { v[0] = (V >> 8) & 0xFF; v[1] = (V ) & 0xFF; } operator Type () const { #if ((defined(__GNUC__) && __GNUC__ >= 5) || defined(__clang__)) && \ defined(__BYTE_ORDER) && \ (__BYTE_ORDER == __LITTLE_ENDIAN || __BYTE_ORDER == __BIG_ENDIAN) /* Spoon-feed the compiler a big-endian integer with alignment 1. * https://github.com/harfbuzz/harfbuzz/pull/1398 */ struct __attribute__((packed)) packed_uint16_t { uint16_t v; }; #if __BYTE_ORDER == __LITTLE_ENDIAN return __builtin_bswap16 (((packed_uint16_t *) this)->v); #else /* __BYTE_ORDER == __BIG_ENDIAN */ return ((packed_uint16_t *) this)->v; #endif #endif return (v[0] << 8) + (v[1] ); } private: uint8_t v[2]; }; template struct BEInt { public: void set (Type V) { v[0] = (V >> 16) & 0xFF; v[1] = (V >> 8) & 0xFF; v[2] = (V ) & 0xFF; } operator Type () const { return (v[0] << 16) + (v[1] << 8) + (v[2] ); } private: uint8_t v[3]; }; template struct BEInt { public: typedef Type type; void set (Type V) { v[0] = (V >> 24) & 0xFF; v[1] = (V >> 16) & 0xFF; v[2] = (V >> 8) & 0xFF; v[3] = (V ) & 0xFF; } operator Type () const { return (v[0] << 24) + (v[1] << 16) + (v[2] << 8) + (v[3] ); } private: uint8_t v[4]; }; /* * Lazy loaders. */ template struct hb_data_wrapper_t { static_assert (WheresData > 0, ""); Data * get_data () const { return *(((Data **) (void *) this) - WheresData); } bool is_inert () const { return !get_data (); } template Stored * call_create () const { return Subclass::create (get_data ()); } }; template <> struct hb_data_wrapper_t { bool is_inert () const { return false; } template Stored * call_create () const { return Funcs::create (); } }; template struct hb_non_void_t { typedef T1 value; }; template struct hb_non_void_t { typedef T2 value; }; template struct hb_lazy_loader_t : hb_data_wrapper_t { typedef typename hb_non_void_t >::value Funcs; void init0 () {} /* Init, when memory is already set to 0. No-op for us. */ void init () { instance.set_relaxed (nullptr); } void fini () { do_destroy (instance.get ()); } void free_instance () { retry: Stored *p = instance.get (); if (unlikely (p && !cmpexch (p, nullptr))) goto retry; do_destroy (p); } static void do_destroy (Stored *p) { if (p && p != const_cast (Funcs::get_null ())) Funcs::destroy (p); } const Returned * operator -> () const { return get (); } const Returned & operator * () const { return *get (); } explicit_operator bool () const { return get_stored () != Funcs::get_null (); } template operator const C * () const { return get (); } Stored * get_stored () const { retry: Stored *p = this->instance.get (); if (unlikely (!p)) { if (unlikely (this->is_inert ())) return const_cast (Funcs::get_null ()); p = this->template call_create (); if (unlikely (!p)) p = const_cast (Funcs::get_null ()); if (unlikely (!cmpexch (nullptr, p))) { do_destroy (p); goto retry; } } return p; } Stored * get_stored_relaxed () const { return this->instance.get_relaxed (); } bool cmpexch (Stored *current, Stored *value) const { /* This *must* be called when there are no other threads accessing. */ return this->instance.cmpexch (current, value); } const Returned * get () const { return Funcs::convert (get_stored ()); } const Returned * get_relaxed () const { return Funcs::convert (get_stored_relaxed ()); } Returned * get_unconst () const { return const_cast (Funcs::convert (get_stored ())); } /* To be possibly overloaded by subclasses. */ static Returned* convert (Stored *p) { return p; } /* By default null/init/fini the object. */ static const Stored* get_null () { return &Null(Stored); } static Stored *create (Data *data) { Stored *p = (Stored *) calloc (1, sizeof (Stored)); if (likely (p)) p->init (data); return p; } static Stored *create () { Stored *p = (Stored *) calloc (1, sizeof (Stored)); if (likely (p)) p->init (); return p; } static void destroy (Stored *p) { p->fini (); free (p); } // private: /* Must only have one pointer. */ hb_atomic_ptr_t instance; }; /* Specializations. */ template struct hb_face_lazy_loader_t : hb_lazy_loader_t, hb_face_t, WheresFace> {}; template struct hb_table_lazy_loader_t : hb_lazy_loader_t, hb_face_t, WheresFace, hb_blob_t> { static hb_blob_t *create (hb_face_t *face) { return hb_sanitize_context_t ().reference_table (face); } static void destroy (hb_blob_t *p) { hb_blob_destroy (p); } static const hb_blob_t *get_null () { return hb_blob_get_empty (); } static const T* convert (const hb_blob_t *blob) { return blob->as (); } hb_blob_t* get_blob () const { return this->get_stored (); } }; template struct hb_font_funcs_lazy_loader_t : hb_lazy_loader_t { static void destroy (hb_font_funcs_t *p) { hb_font_funcs_destroy (p); } static const hb_font_funcs_t *get_null () { return hb_font_funcs_get_empty (); } }; template struct hb_unicode_funcs_lazy_loader_t : hb_lazy_loader_t { static void destroy (hb_unicode_funcs_t *p) { hb_unicode_funcs_destroy (p); } static const hb_unicode_funcs_t *get_null () { return hb_unicode_funcs_get_empty (); } }; #endif /* HB_MACHINERY_HH */