Split sanitize and dispatch into their own files
This commit is contained in:
Behdad Esfahbod
parent
be66b575fc
commit
a7c63cd8f8
@ -32,6 +32,7 @@ HB_BASE_sources = \
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hb-cff2-interp-cs.hh \
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hb-common.cc \
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hb-debug.hh \
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hb-dispatch.hh \
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hb-face.cc \
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hb-face.hh \
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hb-font.cc \
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@ -128,6 +129,7 @@ HB_BASE_sources = \
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hb-ot-var-mvar-table.hh \
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hb-ot-var.cc \
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hb-ot-vorg-table.hh \
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hb-sanitize.hh \
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hb-serialize.hh \
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hb-set-digest.hh \
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hb-set.cc \
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50
src/hb-dispatch.hh
Normal file
50
src/hb-dispatch.hh
Normal file
@ -0,0 +1,50 @@
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/*
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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_DISPATCH_HH
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#define HB_DISPATCH_HH
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#include "hb.hh"
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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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static constexpr unsigned 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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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 () { return Context::default_return_value (); }
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static bool stop_sublookup_iteration (const return_t r HB_UNUSED) { return false; }
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};
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#endif /* HB_DISPATCH_HH */
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@ -32,6 +32,8 @@
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#include "hb.hh"
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#include "hb-blob.hh"
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#include "hb-dispatch.hh"
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#include "hb-sanitize.hh"
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#include "hb-serialize.hh"
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@ -142,373 +144,6 @@ static inline Type& StructAfter(TObject &X)
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DEFINE_SIZE_ARRAY(size, array)
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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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static constexpr unsigned 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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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 () { return Context::default_return_value (); }
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static bool stop_sublookup_iteration (const return_t r HB_UNUSED) { return false; }
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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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hb_sanitize_context_t () :
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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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const char *get_name () { return "SANITIZE"; }
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template <typename T, typename F>
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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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return_t dispatch (const T &obj) { return obj.sanitize (this); }
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static return_t default_return_value () { return true; }
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static return_t no_dispatch_return_value () { return false; }
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bool stop_sublookup_iteration (const return_t r) const { return !r; }
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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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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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unsigned int get_num_glyphs () { return num_glyphs; }
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void set_max_ops (int max_ops_) { max_ops = max_ops_; }
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template <typename T>
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void set_object (const T *obj)
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{
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reset_object ();
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if (!obj) return;
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const char *obj_start = (const char *) obj;
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if (unlikely (obj_start < this->start || this->end <= obj_start))
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this->start = this->end = nullptr;
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else
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{
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this->start = obj_start;
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this->end = obj_start + MIN<uintptr_t> (this->end - obj_start, obj->get_size ());
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}
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}
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void reset_object ()
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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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}
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void start_processing ()
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{
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reset_object ();
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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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void end_processing ()
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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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bool check_range (const void *base,
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unsigned int len) const
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{
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const char *p = (const char *) base;
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bool ok = !len ||
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(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]"
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" (%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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bool check_range (const T *base,
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unsigned int a,
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unsigned int b) const
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{
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return !hb_unsigned_mul_overflows (a, b) &&
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this->check_range (base, a * b);
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}
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template <typename T>
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bool check_range (const T *base,
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unsigned int a,
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unsigned int b,
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unsigned int c) const
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{
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return !hb_unsigned_mul_overflows (a, b) &&
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this->check_range (base, a * b, c);
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}
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template <typename T>
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bool check_array (const T *base, unsigned int len) const
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{
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return this->check_range (base, len, hb_static_size (T));
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}
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template <typename T>
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bool check_array (const T *base,
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unsigned int a,
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unsigned int b) const
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{
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return this->check_range (base, a, b, hb_static_size (T));
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}
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template <typename Type>
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bool check_struct (const Type *obj) const
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{ return likely (this->check_range (obj, obj->min_size)); }
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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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bool try_set (const Type *obj, const ValueType &v)
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{
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if (this->may_edit (obj, hb_static_size (Type)))
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{
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* const_cast<Type *> (obj) = 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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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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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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struct hb_sanitize_with_object_t
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{
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template <typename T>
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hb_sanitize_with_object_t (hb_sanitize_context_t *c, const T& obj) : c (c)
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{ c->set_object (obj); }
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~hb_sanitize_with_object_t ()
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{ c->reset_object (); }
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private:
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hb_sanitize_context_t *c;
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};
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|
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/*
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* Big-endian integers.
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*/
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388
src/hb-sanitize.hh
Normal file
388
src/hb-sanitize.hh
Normal file
@ -0,0 +1,388 @@
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/*
|
||||
* 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_SANITIZE_HH
|
||||
#define HB_SANITIZE_HH
|
||||
|
||||
#include "hb.hh"
|
||||
#include "hb-blob.hh"
|
||||
#include "hb-dispatch.hh"
|
||||
|
||||
|
||||
/*
|
||||
* 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<OT::head> (face);
|
||||
*
|
||||
* The blob then can be converted to a head table struct with:
|
||||
*
|
||||
* const head *head_table = head_blob->as<head> ();
|
||||
*
|
||||
* 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, bool, HB_DEBUG_SANITIZE>
|
||||
{
|
||||
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 <typename T, typename F>
|
||||
bool may_dispatch (const T *obj HB_UNUSED, const F *format)
|
||||
{ return format->sanitize (this); }
|
||||
template <typename T>
|
||||
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 <typename T>
|
||||
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<uintptr_t> (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 = !len ||
|
||||
(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 <typename T>
|
||||
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 <typename T>
|
||||
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 <typename T>
|
||||
bool check_array (const T *base, unsigned int len) const
|
||||
{
|
||||
return this->check_range (base, len, hb_static_size (T));
|
||||
}
|
||||
|
||||
template <typename T>
|
||||
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 <typename Type>
|
||||
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 <typename Type, typename ValueType>
|
||||
bool try_set (const Type *obj, const ValueType &v)
|
||||
{
|
||||
if (this->may_edit (obj, hb_static_size (Type)))
|
||||
{
|
||||
* const_cast<Type *> (obj) = v;
|
||||
return true;
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
template <typename Type>
|
||||
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 = reinterpret_cast<Type *> (const_cast<char *> (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 <typename Type>
|
||||
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<Type> (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 <typename T>
|
||||
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;
|
||||
};
|
||||
|
||||
|
||||
#endif /* HB_SANITIZE_HH */
|
||||
Loading…
Reference in New Issue
Block a user