The Tor Browser: js/public/Utility.h@97036ab72558 (annotated)

js/public/Utility.h@97036ab72558 (annotated)

js/public/Utility.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifndef js_Utility_h
 #define js_Utility_h
 #include "mozilla/Assertions.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/Compiler.h"
 #include "mozilla/Move.h"
 #include "mozilla/NullPtr.h"
 #include "mozilla/Scoped.h"
 #include "mozilla/TemplateLib.h"
 #include <stdlib.h>
 #include <string.h>
 #ifdef JS_OOM_DO_BACKTRACES
 #include <execinfo.h>
 #include <stdio.h>
 #endif
 #include "jstypes.h"
 /* The public JS engine namespace. */
 namespace JS {}
 /* The mozilla-shared reusable template/utility namespace. */
 namespace mozilla {}
 /* The private JS engine namespace. */
 namespace js {}
 /*
  * Patterns used by SpiderMonkey to overwrite unused memory. If you are
  * accessing an object with one of these pattern, you probably have a dangling
  * pointer.
  */
 #define JS_FRESH_NURSERY_PATTERN 0x2F
 #define JS_SWEPT_NURSERY_PATTERN 0x2B
 #define JS_ALLOCATED_NURSERY_PATTERN 0x2D
 #define JS_FRESH_TENURED_PATTERN 0x4F
 #define JS_SWEPT_TENURED_PATTERN 0x4B
 #define JS_ALLOCATED_TENURED_PATTERN 0x4D
 #define JS_SWEPT_CODE_PATTERN 0x3b
 #define JS_SWEPT_FRAME_PATTERN 0x5b
 #define JS_ASSERT(expr)           MOZ_ASSERT(expr)
 #define JS_ASSERT_IF(cond, expr)  MOZ_ASSERT_IF(cond, expr)
 #define JS_STATIC_ASSERT(cond)           static_assert(cond, "JS_STATIC_ASSERT")
 #define JS_STATIC_ASSERT_IF(cond, expr)  MOZ_STATIC_ASSERT_IF(cond, expr, "JS_STATIC_ASSERT_IF")
 extern MOZ_NORETURN JS_PUBLIC_API(void)
 JS_Assert(const char *s, const char *file, int ln);
 /*
  * Abort the process in a non-graceful manner. This will cause a core file,
  * call to the debugger or other moral equivalent as well as causing the
  * entire process to stop.
  */
 extern JS_PUBLIC_API(void) JS_Abort(void);
 /*
  * Custom allocator support for SpiderMonkey
  */
 #if defined JS_USE_CUSTOM_ALLOCATOR
 # include "jscustomallocator.h"
 #else
 # if defined(DEBUG) || defined(JS_OOM_BREAKPOINT)
 /*
  * In order to test OOM conditions, when the testing function
  * oomAfterAllocations COUNT is passed, we fail continuously after the NUM'th
  * allocation from now.
  */
 extern JS_PUBLIC_DATA(uint32_t) OOM_maxAllocations; /* set in builtin/TestingFunctions.cpp */
 extern JS_PUBLIC_DATA(uint32_t) OOM_counter; /* data race, who cares. */
 #ifdef JS_OOM_BREAKPOINT
 static MOZ_NEVER_INLINE void js_failedAllocBreakpoint() { asm(""); }
 #define JS_OOM_CALL_BP_FUNC() js_failedAllocBreakpoint()
 #else
 #define JS_OOM_CALL_BP_FUNC() do {} while(0)
 #endif
 #  define JS_OOM_POSSIBLY_FAIL() \
     do \
     { \
         if (++OOM_counter > OOM_maxAllocations) { \
             JS_OOM_CALL_BP_FUNC();\
             return nullptr; \
         } \
     } while (0)
 # else
 #  define JS_OOM_POSSIBLY_FAIL() do {} while(0)
 # endif /* DEBUG || JS_OOM_BREAKPOINT */
 static inline void* js_malloc(size_t bytes)
 {
     JS_OOM_POSSIBLY_FAIL();
     return malloc(bytes);
 }
 static inline void* js_calloc(size_t bytes)
 {
     JS_OOM_POSSIBLY_FAIL();
     return calloc(bytes, 1);
 }
 static inline void* js_calloc(size_t nmemb, size_t size)
 {
     JS_OOM_POSSIBLY_FAIL();
     return calloc(nmemb, size);
 }
 static inline void* js_realloc(void* p, size_t bytes)
 {
     JS_OOM_POSSIBLY_FAIL();
     return realloc(p, bytes);
 }
 static inline void js_free(void* p)
 {
     free(p);
 }
 #endif/* JS_USE_CUSTOM_ALLOCATOR */
 #include <new>
 /*
  * Low-level memory management in SpiderMonkey:
  *
  *  ** Do not use the standard malloc/free/realloc: SpiderMonkey allows these
  *     to be redefined (via JS_USE_CUSTOM_ALLOCATOR) and Gecko even #define's
  *     these symbols.
  *
  *  ** Do not use the builtin C++ operator new and delete: these throw on
  *     error and we cannot override them not to.
  *
  * Allocation:
  *
  * - If the lifetime of the allocation is tied to the lifetime of a GC-thing
  *   (that is, finalizing the GC-thing will free the allocation), call one of
  *   the following functions:
  *
  *     JSContext::{malloc_,realloc_,calloc_,new_}
  *     JSRuntime::{malloc_,realloc_,calloc_,new_}
  *
  *   These functions accumulate the number of bytes allocated which is used as
  *   part of the GC-triggering heuristic.
  *
  *   The difference between the JSContext and JSRuntime versions is that the
  *   cx version reports an out-of-memory error on OOM. (This follows from the
  *   general SpiderMonkey idiom that a JSContext-taking function reports its
  *   own errors.)
  *
  * - Otherwise, use js_malloc/js_realloc/js_calloc/js_free/js_new
  *
  * Deallocation:
  *
  * - Ordinarily, use js_free/js_delete.
  *
  * - For deallocations during GC finalization, use one of the following
  *   operations on the FreeOp provided to the finalizer:
  *
  *     FreeOp::{free_,delete_}
  *
  *   The advantage of these operations is that the memory is batched and freed
  *   on another thread.
  */
 #define JS_NEW_BODY(allocator, t, parms)                                       \
     void *memory = allocator(sizeof(t));                                       \
     return memory ? new(memory) t parms : nullptr;
 /*
  * Given a class which should provide 'new' methods, add
  * JS_DECLARE_NEW_METHODS (see JSContext for a usage example). This
  * adds news with up to 12 parameters. Add more versions of new below if
  * you need more than 12 parameters.
  *
  * Note: Do not add a ; at the end of a use of JS_DECLARE_NEW_METHODS,
  * or the build will break.
  */
 #define JS_DECLARE_NEW_METHODS(NEWNAME, ALLOCATOR, QUALIFIERS)\
     template <class T>\
     QUALIFIERS T *NEWNAME() MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T, ())\
     }\
 \
     template <class T, class P1>\
     QUALIFIERS T *NEWNAME(P1 &&p1) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1)))\
     }\
 \
     template <class T, class P1, class P2>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2)))\
     }\
 \
     template <class T, class P1, class P2, class P3>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2, P3 &&p3) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2),\
                      mozilla::Forward<P3>(p3)))\
     }\
 \
     template <class T, class P1, class P2, class P3, class P4>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2, P3 &&p3, P4 &&p4) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2),\
                      mozilla::Forward<P3>(p3),\
                      mozilla::Forward<P4>(p4)))\
     }\
 \
     template <class T, class P1, class P2, class P3, class P4, class P5>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2, P3 &&p3, P4 &&p4, P5 &&p5) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2),\
                      mozilla::Forward<P3>(p3),\
                      mozilla::Forward<P4>(p4),\
                      mozilla::Forward<P5>(p5)))\
     }\
 \
     template <class T, class P1, class P2, class P3, class P4, class P5, class P6>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2, P3 &&p3, P4 &&p4, P5 &&p5, P6 &&p6) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2),\
                      mozilla::Forward<P3>(p3),\
                      mozilla::Forward<P4>(p4),\
                      mozilla::Forward<P5>(p5),\
                      mozilla::Forward<P6>(p6)))\
     }\
 \
     template <class T, class P1, class P2, class P3, class P4, class P5, class P6, class P7>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2, P3 &&p3, P4 &&p4, P5 &&p5, P6 &&p6, P7 &&p7) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2),\
                      mozilla::Forward<P3>(p3),\
                      mozilla::Forward<P4>(p4),\
                      mozilla::Forward<P5>(p5),\
                      mozilla::Forward<P6>(p6),\
                      mozilla::Forward<P7>(p7)))\
     }\
 \
     template <class T, class P1, class P2, class P3, class P4, class P5, class P6, class P7, class P8>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2, P3 &&p3, P4 &&p4, P5 &&p5, P6 &&p6, P7 &&p7, P8 &&p8) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2),\
                      mozilla::Forward<P3>(p3),\
                      mozilla::Forward<P4>(p4),\
                      mozilla::Forward<P5>(p5),\
                      mozilla::Forward<P6>(p6),\
                      mozilla::Forward<P7>(p7),\
                      mozilla::Forward<P8>(p8)))\
     }\
 \
     template <class T, class P1, class P2, class P3, class P4, class P5, class P6, class P7, class P8, class P9>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2, P3 &&p3, P4 &&p4, P5 &&p5, P6 &&p6, P7 &&p7, P8 &&p8, P9 &&p9) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2),\
                      mozilla::Forward<P3>(p3),\
                      mozilla::Forward<P4>(p4),\
                      mozilla::Forward<P5>(p5),\
                      mozilla::Forward<P6>(p6),\
                      mozilla::Forward<P7>(p7),\
                      mozilla::Forward<P8>(p8),\
                      mozilla::Forward<P9>(p9)))\
     }\
 \
     template <class T, class P1, class P2, class P3, class P4, class P5, class P6, class P7, class P8, class P9, class P10>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2, P3 &&p3, P4 &&p4, P5 &&p5, P6 &&p6, P7 &&p7, P8 &&p8, P9 &&p9, P10 &&p10) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2),\
                      mozilla::Forward<P3>(p3),\
                      mozilla::Forward<P4>(p4),\
                      mozilla::Forward<P5>(p5),\
                      mozilla::Forward<P6>(p6),\
                      mozilla::Forward<P7>(p7),\
                      mozilla::Forward<P8>(p8),\
                      mozilla::Forward<P9>(p9),\
                      mozilla::Forward<P10>(p10)))\
     }\
 \
     template <class T, class P1, class P2, class P3, class P4, class P5, class P6, class P7, class P8, class P9, class P10, class P11>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2, P3 &&p3, P4 &&p4, P5 &&p5, P6 &&p6, P7 &&p7, P8 &&p8, P9 &&p9, P10 &&p10, P11 &&p11) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2),\
                      mozilla::Forward<P3>(p3),\
                      mozilla::Forward<P4>(p4),\
                      mozilla::Forward<P5>(p5),\
                      mozilla::Forward<P6>(p6),\
                      mozilla::Forward<P7>(p7),\
                      mozilla::Forward<P8>(p8),\
                      mozilla::Forward<P9>(p9),\
                      mozilla::Forward<P10>(p10),\
                      mozilla::Forward<P11>(p11)))\
     }\
 \
     template <class T, class P1, class P2, class P3, class P4, class P5, class P6, class P7, class P8, class P9, class P10, class P11, class P12>\
     QUALIFIERS T *NEWNAME(P1 &&p1, P2 &&p2, P3 &&p3, P4 &&p4, P5 &&p5, P6 &&p6, P7 &&p7, P8 &&p8, P9 &&p9, P10 &&p10, P11 &&p11, P12 &&p12) MOZ_HEAP_ALLOCATOR {\
         JS_NEW_BODY(ALLOCATOR, T,\
                     (mozilla::Forward<P1>(p1),\
                      mozilla::Forward<P2>(p2),\
                      mozilla::Forward<P3>(p3),\
                      mozilla::Forward<P4>(p4),\
                      mozilla::Forward<P5>(p5),\
                      mozilla::Forward<P6>(p6),\
                      mozilla::Forward<P7>(p7),\
                      mozilla::Forward<P8>(p8),\
                      mozilla::Forward<P9>(p9),\
                      mozilla::Forward<P10>(p10),\
                      mozilla::Forward<P11>(p11),\
                      mozilla::Forward<P12>(p12)))\
     }\
 JS_DECLARE_NEW_METHODS(js_new, js_malloc, static MOZ_ALWAYS_INLINE)
 template <class T>
 static MOZ_ALWAYS_INLINE void
 js_delete(T *p)
 {
     if (p) {
         p->~T();
         js_free(p);
     }
 }
 template<class T>
 static MOZ_ALWAYS_INLINE void
 js_delete_poison(T *p)
 {
     if (p) {
         p->~T();
         memset(p, 0x3B, sizeof(T));
         js_free(p);
     }
 }
 template <class T>
 static MOZ_ALWAYS_INLINE T *
 js_pod_malloc()
 {
     return (T *)js_malloc(sizeof(T));
 }
 template <class T>
 static MOZ_ALWAYS_INLINE T *
 js_pod_calloc()
 {
     return (T *)js_calloc(sizeof(T));
 }
 template <class T>
 static MOZ_ALWAYS_INLINE T *
 js_pod_malloc(size_t numElems)
 {
     if (numElems & mozilla::tl::MulOverflowMask<sizeof(T)>::value)
         return nullptr;
     return (T *)js_malloc(numElems * sizeof(T));
 }
 template <class T>
 static MOZ_ALWAYS_INLINE T *
 js_pod_calloc(size_t numElems)
 {
     if (numElems & mozilla::tl::MulOverflowMask<sizeof(T)>::value)
         return nullptr;
     return (T *)js_calloc(numElems * sizeof(T));
 }
 namespace js {
 template<typename T>
 struct ScopedFreePtrTraits
 {
     typedef T* type;
     static T* empty() { return nullptr; }
     static void release(T* ptr) { js_free(ptr); }
 };
 SCOPED_TEMPLATE(ScopedJSFreePtr, ScopedFreePtrTraits)
 template <typename T>
 struct ScopedDeletePtrTraits : public ScopedFreePtrTraits<T>
 {
     static void release(T *ptr) { js_delete(ptr); }
 };
 SCOPED_TEMPLATE(ScopedJSDeletePtr, ScopedDeletePtrTraits)
 template <typename T>
 struct ScopedReleasePtrTraits : public ScopedFreePtrTraits<T>
 {
     static void release(T *ptr) { if (ptr) ptr->release(); }
 };
 SCOPED_TEMPLATE(ScopedReleasePtr, ScopedReleasePtrTraits)
 } /* namespace js */
 namespace js {
 /* Integral types for all hash functions. */
 typedef uint32_t HashNumber;
 const unsigned HashNumberSizeBits = 32;
 namespace detail {
 /*
  * Given a raw hash code, h, return a number that can be used to select a hash
  * bucket.
  *
  * This function aims to produce as uniform an output distribution as possible,
  * especially in the most significant (leftmost) bits, even though the input
  * distribution may be highly nonrandom, given the constraints that this must
  * be deterministic and quick to compute.
  *
  * Since the leftmost bits of the result are best, the hash bucket index is
  * computed by doing ScrambleHashCode(h) / (2^32/N) or the equivalent
  * right-shift, not ScrambleHashCode(h) % N or the equivalent bit-mask.
  *
  * FIXME: OrderedHashTable uses a bit-mask; see bug 775896.
  */
 inline HashNumber
 ScrambleHashCode(HashNumber h)
 {
     /*
      * Simply returning h would not cause any hash tables to produce wrong
      * answers. But it can produce pathologically bad performance: The caller
      * right-shifts the result, keeping only the highest bits. The high bits of
      * hash codes are very often completely entropy-free. (So are the lowest
      * bits.)
      *
      * So we use Fibonacci hashing, as described in Knuth, The Art of Computer
      * Programming, 6.4. This mixes all the bits of the input hash code h.
      *
      * The value of goldenRatio is taken from the hex
      * expansion of the golden ratio, which starts 1.9E3779B9....
      * This value is especially good if values with consecutive hash codes
      * are stored in a hash table; see Knuth for details.
      */
     static const HashNumber goldenRatio = 0x9E3779B9U;
     return h * goldenRatio;
 }
 } /* namespace detail */
 } /* namespace js */
 namespace JS {
 /*
  * Methods for poisoning GC heap pointer words and checking for poisoned words.
  * These are in this file for use in Value methods and so forth.
  *
  * If the moving GC hazard analysis is in use and detects a non-rooted stack
  * pointer to a GC thing, one byte of that pointer is poisoned to refer to an
  * invalid location. For both 32 bit and 64 bit systems, the fourth byte of the
  * pointer is overwritten, to reduce the likelihood of accidentally changing
  * a live integer value.
  */
 inline void PoisonPtr(void *v)
 {
 #if defined(JSGC_ROOT_ANALYSIS) && defined(JS_DEBUG)
     uint8_t *ptr = (uint8_t *) v + 3;
     *ptr = JS_FREE_PATTERN;
 #endif
 }
 template <typename T>
 inline bool IsPoisonedPtr(T *v)
 {
 #if defined(JSGC_ROOT_ANALYSIS) && defined(JS_DEBUG)
     uint32_t mask = uintptr_t(v) & 0xff000000;
     return mask == uint32_t(JS_FREE_PATTERN << 24);
 #else
     return false;
 #endif
 }
 }
 /* sixgill annotation defines */
 #ifndef HAVE_STATIC_ANNOTATIONS
 # define HAVE_STATIC_ANNOTATIONS
 # ifdef XGILL_PLUGIN
 #  define STATIC_PRECONDITION(COND)         __attribute__((precondition(#COND)))
 #  define STATIC_PRECONDITION_ASSUME(COND)  __attribute__((precondition_assume(#COND)))
 #  define STATIC_POSTCONDITION(COND)        __attribute__((postcondition(#COND)))
 #  define STATIC_POSTCONDITION_ASSUME(COND) __attribute__((postcondition_assume(#COND)))
 #  define STATIC_INVARIANT(COND)            __attribute__((invariant(#COND)))
 #  define STATIC_INVARIANT_ASSUME(COND)     __attribute__((invariant_assume(#COND)))
 #  define STATIC_PASTE2(X,Y) X ## Y
 #  define STATIC_PASTE1(X,Y) STATIC_PASTE2(X,Y)
 #  define STATIC_ASSERT(COND)                        \
   JS_BEGIN_MACRO                                     \
     __attribute__((assert_static(#COND), unused))    \
     int STATIC_PASTE1(assert_static_, __COUNTER__);  \
   JS_END_MACRO
 #  define STATIC_ASSUME(COND)                        \
   JS_BEGIN_MACRO                                     \
     __attribute__((assume_static(#COND), unused))    \
     int STATIC_PASTE1(assume_static_, __COUNTER__);  \
   JS_END_MACRO
 #  define STATIC_ASSERT_RUNTIME(COND)                       \
   JS_BEGIN_MACRO                                            \
     __attribute__((assert_static_runtime(#COND), unused))   \
     int STATIC_PASTE1(assert_static_runtime_, __COUNTER__); \
   JS_END_MACRO
 # else /* XGILL_PLUGIN */
 #  define STATIC_PRECONDITION(COND)          /* nothing */
 #  define STATIC_PRECONDITION_ASSUME(COND)   /* nothing */
 #  define STATIC_POSTCONDITION(COND)         /* nothing */
 #  define STATIC_POSTCONDITION_ASSUME(COND)  /* nothing */
 #  define STATIC_INVARIANT(COND)             /* nothing */
 #  define STATIC_INVARIANT_ASSUME(COND)      /* nothing */
 #  define STATIC_ASSERT(COND)          JS_BEGIN_MACRO /* nothing */ JS_END_MACRO
 #  define STATIC_ASSUME(COND)          JS_BEGIN_MACRO /* nothing */ JS_END_MACRO
 #  define STATIC_ASSERT_RUNTIME(COND)  JS_BEGIN_MACRO /* nothing */ JS_END_MACRO
 # endif /* XGILL_PLUGIN */
 # define STATIC_SKIP_INFERENCE STATIC_INVARIANT(skip_inference())
 #endif /* HAVE_STATIC_ANNOTATIONS */
 #endif /* js_Utility_h */

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js/public/Utility.h@97036ab72558 (annotated)

js/public/Utility.h