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Edit File : memory.h \| Size : 23.13 KB
#ifndef RBIMPL_MEMORY_H /--C++--vi:se ft=cpp:/ #define RBIMPL_MEMORY_H /** * @file * @author Ruby developers <ruby-core@ruby-lang.org> * @copyright This file is a part of the programming language Ruby. * Permission is hereby granted, to either redistribute and/or * modify this file, provided that the conditions mentioned in the * file COPYING are met. Consult the file for details. * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are * implementation details. Don't take them as canon. They could * rapidly appear then vanish. The name (path) of this header file * is also an implementation detail. Do not expect it to persist * at the place it is now. Developers are free to move it anywhere * anytime at will. * @note To ruby-core: remember that this header can be possibly * recursively included from extension libraries written in C++. * Do not expect for instance `__VA_ARGS__` is always available. * We assume C99 for ruby itself but we don't assume languages of * extension libraries. They could be written in C++98. * @brief Memory management stuff. / #include "ruby/internal/config.h" #ifdef STDC_HEADERS # include <stddef.h> #endif #ifdef HAVE_STRING_H # include <string.h> #endif #ifdef HAVE_STDINT_H # include <stdint.h> #endif #ifdef HAVE_ALLOCA_H # include <alloca.h> #endif #if defined(_MSC_VER) && defined(_WIN64) # include <intrin.h> # pragma intrinsic(_umul128) #endif #include "ruby/internal/attr/alloc_size.h" #include "ruby/internal/attr/const.h" #include "ruby/internal/attr/constexpr.h" #include "ruby/internal/attr/noalias.h" #include "ruby/internal/attr/nonnull.h" #include "ruby/internal/attr/noreturn.h" #include "ruby/internal/attr/restrict.h" #include "ruby/internal/attr/returns_nonnull.h" #include "ruby/internal/cast.h" #include "ruby/internal/dllexport.h" #include "ruby/internal/has/builtin.h" #include "ruby/internal/stdalign.h" #include "ruby/internal/stdbool.h" #include "ruby/internal/xmalloc.h" #include "ruby/backward/2/limits.h" #include "ruby/backward/2/long_long.h" #include "ruby/backward/2/assume.h" #include "ruby/defines.h" /* @cond INTENAL_MACRO / / Make alloca work the best possible way. / #if defined(alloca) # / Take that. / #elif RBIMPL_HAS_BUILTIN(__builtin_alloca) # define alloca __builtin_alloca #elif defined(_AIX) # pragma alloca #elif defined(__cplusplus) extern "C" void alloca(size_t); #else extern void alloca(); #endif /* @endcond / #if defined(__DOXYGEN__) /* * @private * * Type that is as twice wider as size_t. This is an implementation detail of * rb_mul_size_overflow(). People should not use it. This is not a good name * either. / typedef uint128_t DSIZE_T; #elif defined(HAVE_INT128_T) && SIZEOF_SIZE_T <= 8 # define DSIZE_T uint128_t #elif SIZEOF_SIZE_T 2 <= SIZEOF_LONG_LONG # define DSIZE_T unsigned LONG_LONG #endif /** * @private * * Maximum possible number of bytes that #RB_ALLOCV can allocate using * `alloca`. Anything beyond this is allocated using rb_alloc_tmp_buffer(). * This selection is transparent to users. People don't have to bother. / #ifdef C_ALLOCA # define RUBY_ALLOCV_LIMIT 0 #else # define RUBY_ALLOCV_LIMIT 1024 #endif /* * Prevents premature destruction of local objects. Ruby's garbage collector * is conservative; it scans the C level machine stack as well. Possible in- * use Ruby objects must remain visible on stack, to be properly marked as * such. However contemporary C compilers do not interface well with this. * Consider the following example: * * ```CXX * auto s = rb_str_new_cstr(" world"); * auto sptr = RSTRING_PTR(s); * auto t = rb_str_new_cstr("hello,"); // Possible GC invocation * auto u = rb_str_cat_cstr(t, sptr); * * RB_GC_GUARD(s); // ensure `s` (and thus `sptr`) do not get GC-ed * ``` * * Here, without the #RB_GC_GUARD, the last use of `s` is _before_ the last use * of `sptr`. Compilers could thus think `s` and `t` are allowed to overlap. * That would eliminate `s` from the stack, while `sptr` is still in use. If * our GC ran at that very moment, `s` gets swept out, which also destroys * `sptr`. Boom! You got a SEGV. * * In order to prevent this scenario #RB_GC_GUARD must be placed _after_ the * last use of `sptr`. Placing #RB_GC_GUARD before dereferencing `sptr` would * be of no use. * * #RB_GC_GUARD would not be necessary at all in the above example if non- * inlined function calls are made on the `s` variable after `sptr` is * dereferenced. Thus, in the above example, calling any un-inlined function * on `s` such as `rb_str_modify(s);` will ensure `s` stays on the stack or * register to prevent a GC invocation from prematurely freeing it. * * Using the #RB_GC_GUARD macro is preferable to using the `volatile` keyword * in C. #RB_GC_GUARD has the following advantages: * * - the intent of the macro use is clear. * * - #RB_GC_GUARD only affects its call site. OTOH `volatile` generates some * extra code every time the variable is used, hurting optimisation. * * - `volatile` implementations may be buggy/inconsistent in some compilers * and architectures. #RB_GC_GUARD is customisable for broken * systems/compilers without negatively affecting other systems. * * - C++ since C++20 deprecates `volatile`. If you write your extension * library in that language there is no escape but to use this macro. * * @param v A variable of ::VALUE type. * @post `v` is still alive. / #ifdef __GNUC__ #define RB_GC_GUARD(v) \ (__extension__ ({ \ volatile VALUE rb_gc_guarded_ptr = &(v); \ __asm__("" : : "m"(rb_gc_guarded_ptr)); \ rb_gc_guarded_ptr; \ })) #elif defined _MSC_VER #define RB_GC_GUARD(v) (rb_gc_guarded_ptr(&(v))) #else #define HAVE_RB_GC_GUARDED_PTR_VAL 1 #define RB_GC_GUARD(v) (rb_gc_guarded_ptr_val(&(v),(v))) #endif / Casts needed because void* is NOT compatible with others in C++. / /* * Convenient macro that allocates an array of n elements. * * @param type Type of array elements. * @param n Length of the array. * @exception rb_eNoMemError No space left for allocation. * @exception rb_eArgError Integer overflow trying to calculate the length * of continuous memory region of `n` elements of * `type`. * @return Storage instance that is capable of storing at least `n` * elements of type `type`. * @note It doesn't return NULL, even when `n` is zero. * @warning The return value shall be invalidated exactly once by either * ruby_xfree(), ruby_xrealloc(), or ruby_xrealloc2(). It is a * failure to pass it to system free(), because the system and Ruby * might or might not share the same malloc() implementation. / #define RB_ALLOC_N(type,n) RBIMPL_CAST((type )ruby_xmalloc2((n), sizeof(type))) /** * Shorthand of #RB_ALLOC_N with `n=1`. * * @param type Type of allocation. * @exception rb_eNoMemError No space left for allocation. * @return Storage instance that can hold an `type` object. * @note It doesn't return NULL. * @warning The return value shall be invalidated exactly once by either * ruby_xfree(), ruby_xrealloc(), or ruby_xrealloc2(). It is a * failure to pass it to system free(), because the system and Ruby * might or might not share the same malloc() implementation. / #define RB_ALLOC(type) RBIMPL_CAST((type )ruby_xmalloc(sizeof(type))) /** * Identical to #RB_ALLOC_N() but also nullifies the allocated region before * returning. * * @param type Type of array elements. * @param n Length of the array. * @exception rb_eNoMemError No space left for allocation. * @exception rb_eArgError Integer overflow trying to calculate the length * of continuous memory region of `n` elements of * `type`. * @return Storage instance that is capable of storing at least `n` * elements of type `type`. * @post Returned array is filled with zeros. * @note It doesn't return NULL, even when `n` is zero. * @warning The return value shall be invalidated exactly once by either * ruby_xfree(), ruby_xrealloc(), or ruby_xrealloc2(). It is a * failure to pass it to system free(), because the system and Ruby * might or might not share the same malloc() implementation. / #define RB_ZALLOC_N(type,n) RBIMPL_CAST((type )ruby_xcalloc((n), sizeof(type))) /** * Shorthand of #RB_ZALLOC_N with `n=1`. * * @param type Type of allocation. * @exception rb_eNoMemError No space left for allocation. * @return Storage instance that can hold an `type` object. * @post Returned object is filled with zeros. * @note It doesn't return NULL. * @warning The return value shall be invalidated exactly once by either * ruby_xfree(), ruby_xrealloc(), or ruby_xrealloc2(). It is a * failure to pass it to system free(), because the system and Ruby * might or might not share the same malloc() implementation. / #define RB_ZALLOC(type) (RB_ZALLOC_N(type, 1)) /* * Convenient macro that reallocates an array with a new size. * * @param var A variable of `type`, which points to a storage * instance that was previously returned from * either * - ruby_xmalloc(), * - ruby_xmalloc2(), * - ruby_xcalloc(), * - ruby_xrealloc(), or * - ruby_xrealloc2(). * @param type Type of allocation. * @param n Requested new size of each element. * @exception rb_eNoMemError No space left for allocation. * @exception rb_eArgError Integer overflow trying to calculate the length * of continuous memory region of `n` elements of * `type`. * @return Storage instance that is capable of storing at least `n` * elements of type `type`. * @pre The passed variable must point to a valid live storage instance. * It is a failure to pass a variable that holds an already-freed * pointer. * @note It doesn't return NULL, even when `n` is zero. * @warning Do not assume anything on the alignment of the return value. * There is no guarantee that it inherits the passed argument's * one. * @warning The return value shall be invalidated exactly once by either * ruby_xfree(), ruby_xrealloc(), or ruby_xrealloc2(). It is a * failure to pass it to system free(), because the system and Ruby * might or might not share the same malloc() implementation. / #define RB_REALLOC_N(var,type,n) \ ((var) = RBIMPL_CAST((type )ruby_xrealloc2((void )(var), (n), sizeof(type)))) /* * @deprecated This macro is dangerous (does not bother stack overflow at * all). #RB_ALLOCV is the modern way to do the same thing. * @param type Type of array elements. * @param n Length of the array. * @return A pointer on stack. / #define ALLOCA_N(type,n) \ RBIMPL_CAST((type )alloca(rbimpl_size_mul_or_raise(sizeof(type), (n)))) /** * Identical to #RB_ALLOCV_N(), except it implicitly assumes the type of array * is ::VALUE. * * @param v A variable to hold the just-in-case opaque Ruby object. * @param n Size of allocation, in bytes. * @return An array of `n` bytes of ::VALUE. * @note `n` may be evaluated twice. / #define RB_ALLOCV(v, n) \ ((n) < RUBY_ALLOCV_LIMIT ? \ ((v) = 0, alloca(n)) : \ rb_alloc_tmp_buffer(&(v), (n))) /* * Allocates a memory region, possibly on stack. If the given size exceeds * #RUBY_ALLOCV_LIMIT, it allocates a dedicated opaque ruby object instead and * let our GC sweep that region after use. Either way you can fire-and-forget. * * ```CXX * #include <sys/types.h> * * VALUE * foo(int n) * { * VALUE v; * auto ptr = RB_ALLOCV(struct tms, v, n); * ... * // no need to free `ptr`. * } * ``` * * If you want to be super-duper polite you can also explicitly state the end * of use of such memory region by calling #RB_ALLOCV_END(). * * @param type The type of array elements. * @param v A variable to hold the just-in-case opaque Ruby object. * @param n Number of elements requested to allocate. * @return An array of `n` elements of `type`. * @note `n` may be evaluated twice. / #define RB_ALLOCV_N(type, v, n) \ RBIMPL_CAST((type ) \ (((size_t)(n) < RUBY_ALLOCV_LIMIT / sizeof(type)) ? \ ((v) = 0, alloca((n) * sizeof(type))) : \ rb_alloc_tmp_buffer2(&(v), (n), sizeof(type)))) /** * Polite way to declare that the given array is not used any longer. Calling * this not mandatory. Our GC can baby-sit you. However it is not a very bad * idea to use it when possible. Doing so could reduce memory footprint. * * @param v A variable previously passed to either #RB_ALLOCV/#RB_ALLOCV_N. / #define RB_ALLOCV_END(v) rb_free_tmp_buffer(&(v)) /* * Handy macro to erase a region of memory. * * @param p Target pointer. * @param type Type of `p[0]` * @param n Length of `p`. * @return `p`. * @post First `n` elements of `p` are squashed. / #define MEMZERO(p,type,n) memset((p), 0, rbimpl_size_mul_or_raise(sizeof(type), (n))) /* * Handy macro to call memcpy. * * @param p1 Destination pointer. * @param p2 Source pointer. * @param type Type of `p2[0]` * @param n Length of `p2`. * @return `p1`. * @post First `n` elements of `p2` are copied into `p1`. / #define MEMCPY(p1,p2,type,n) memcpy((p1), (p2), rbimpl_size_mul_or_raise(sizeof(type), (n))) /* * Handy macro to call memmove. * * @param p1 Destination pointer. * @param p2 Source pointer. * @param type Type of `p2[0]` * @param n Length of `p2`. * @return `p1`. * @post First `n` elements of `p2` are copied into `p1`. / #define MEMMOVE(p1,p2,type,n) memmove((p1), (p2), rbimpl_size_mul_or_raise(sizeof(type), (n))) /* * Handy macro to call memcmp * * @param p1 Target LHS. * @param p2 Target RHS. * @param type Type of `p1[0]` * @param n Length of `p1`. * @retval <0 `p1` is "less" than `p2`. * @retval 0 `p1` is equal to `p2`. * @retval >0 `p1` is "greater" than `p2`. / #define MEMCMP(p1,p2,type,n) memcmp((p1), (p2), rbimpl_size_mul_or_raise(sizeof(type), (n))) #define ALLOC_N RB_ALLOC_N /< @old{RB_ALLOC_N} / #define ALLOC RB_ALLOC /*< @old{RB_ALLOC} / #define ZALLOC_N RB_ZALLOC_N /*< @old{RB_ZALLOC_N} / #define ZALLOC RB_ZALLOC /*< @old{RB_ZALLOC} / #define REALLOC_N RB_REALLOC_N /*< @old{RB_REALLOC_N} / #define ALLOCV RB_ALLOCV /*< @old{RB_ALLOCV} / #define ALLOCV_N RB_ALLOCV_N /*< @old{RB_ALLOCV_N} / #define ALLOCV_END RB_ALLOCV_END /*< @old{RB_ALLOCV_END} / /** * @private * * This is an implementation detail of rbimpl_size_mul_overflow(). * * @internal * * Expecting this struct to be eliminated by function inlinings. This is * nothing more than std::variant<std::size_t> if we could use recent C++, but * reality is we cannot. / struct rbimpl_size_mul_overflow_tag { bool left; /< Whether overflow happened or not. / size_t right; /*< Multiplication result. / }; RBIMPL_SYMBOL_EXPORT_BEGIN() RBIMPL_ATTR_RESTRICT() RBIMPL_ATTR_RETURNS_NONNULL() RBIMPL_ATTR_ALLOC_SIZE((2)) RBIMPL_ATTR_NONNULL(()) /** * @private * * This is an implementation detail of #RB_ALLOCV(). People don't use this * directly. * * @param[out] store Pointer to a variable. * @param[in] len Requested number of bytes to allocate. * @return Allocated `len` bytes array. * @post `store` holds the corresponding tmp buffer object. / void rb_alloc_tmp_buffer(volatile VALUE store, long len); RBIMPL_ATTR_RESTRICT() RBIMPL_ATTR_RETURNS_NONNULL() RBIMPL_ATTR_ALLOC_SIZE((2,3)) RBIMPL_ATTR_NONNULL(()) /* * @private * * This is an implementation detail of #RB_ALLOCV_N(). People don't use this * directly. * * @param[out] store Pointer to a variable. * @param[in] len Requested number of bytes to allocate. * @param[in] count Number of elements in an array. * @return Allocated `len` bytes array. * @post `store` holds the corresponding tmp buffer object. * * @internal * * Although the meaning of `count` variable is clear, @shyouhei doesn't * understand its needs. / void rb_alloc_tmp_buffer_with_count(volatile VALUE store, size_t len,size_t count); /* * @private * * This is an implementation detail of #RB_ALLOCV_END(). People don't use this * directly. * * @param[out] store Pointer to a variable. * @pre `store` is a NULL, or a pointer to a tmp buffer object. * @post `store` is ::RUBY_Qfalse. @post The object formerly stored in `store` is destroyed. / void rb_free_tmp_buffer(volatile VALUE store); RBIMPL_ATTR_NORETURN() /** * @private * * This is an implementation detail of #RB_ALLOCV_N(). People don't use this * directly. * * @param[in] x Arbitrary value. * @param[in] y Arbitrary value. * @exception rb_eArgError `x` * `y` would integer overflow. / void ruby_malloc_size_overflow(size_t x, size_t y); #ifdef HAVE_RB_GC_GUARDED_PTR_VAL volatile VALUE rb_gc_guarded_ptr_val(volatile VALUE ptr, VALUE val); #endif RBIMPL_SYMBOL_EXPORT_END() #ifdef _MSC_VER # pragma optimize("", off) /* * @private * * This is an implementation detail of #RB_GC_GUARD(). People don't use this * directly. * * @param[in] ptr A pointer to an on-stack C variable. * @return `ptr` as-is. / static inline volatile VALUE rb_gc_guarded_ptr(volatile VALUE ptr) { return ptr; } # pragma optimize("", on) #endif /* * @deprecated This function was an implementation detail of old * #RB_ALLOCV_N(). We no longer use it. @shyouhei suspects that * there are no actual usage now. However it was not marked as * private before. We cannot delete it any longer. * @param[in] a Arbitrary value. * @param[in] b Arbitrary value. * @param[in] max Possible maximum value. * @param[out] c A pointer to return the computation result. * @retval 1 `c` is insane. * @retval 0 `c` is sane. * @post `c` holds `a` * `b`, but could be overflowed. / static inline int rb_mul_size_overflow(size_t a, size_t b, size_t max, size_t c) { #ifdef DSIZE_T RB_GNUC_EXTENSION DSIZE_T da, db, c2; da = a; db = b; c2 = da * db; if (c2 > max) return 1; c = RBIMPL_CAST((size_t)c2); #else if (b != 0 && a > max / b) return 1; c = a * b; #endif return 0; } #if defined(__DOXYGEN__) RBIMPL_ATTR_CONSTEXPR(CXX14) #elif RBIMPL_COMPILER_SINCE(GCC, 7, 0, 0) RBIMPL_ATTR_CONSTEXPR(CXX14) /* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70507 / #elif RBIMPL_COMPILER_SINCE(Clang, 7, 0, 0) RBIMPL_ATTR_CONSTEXPR(CXX14) / https://bugs.llvm.org/show_bug.cgi?id=37633 / #endif RBIMPL_ATTR_CONST() /* * @private * * This is an implementation detail of #RB_ALLOCV_N(). People don't use this * directly. * * @param[in] x Arbitrary value. * @param[in] y Arbitrary value. * @return `{ left, right }`, where `left` is whether there is an integer * overflow or not, and `right` is a (possibly overflowed) result * of `x` * `y`. * * @internal * * This is in fact also an implementation detail of ruby_xmalloc2() etc. / static inline struct rbimpl_size_mul_overflow_tag rbimpl_size_mul_overflow(size_t x, size_t y) { struct rbimpl_size_mul_overflow_tag ret = { false, 0, }; #if RBIMPL_HAS_BUILTIN(__builtin_mul_overflow) ret.left = __builtin_mul_overflow(x, y, &ret.right); #elif defined(DSIZE_T) RB_GNUC_EXTENSION DSIZE_T dx = x; RB_GNUC_EXTENSION DSIZE_T dy = y; RB_GNUC_EXTENSION DSIZE_T dz = dx dy; ret.left = dz > SIZE_MAX; ret.right = RBIMPL_CAST((size_t)dz); #elif defined(_MSC_VER) && defined(_WIN64) unsigned __int64 dp = 0; unsigned __int64 dz = _umul128(x, y, &dp); ret.left = RBIMPL_CAST((bool)dp); ret.right = RBIMPL_CAST((size_t)dz); #else /* https://wiki.sei.cmu.edu/confluence/display/c/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap / ret.left = (y != 0) && (x > SIZE_MAX / y); ret.right = x y; #endif return ret; } /** * @private * * This is an implementation detail of #RB_ALLOCV_N(). People don't use this * directly. * * @param[in] x Arbitrary value. * @param[in] y Arbitrary value. * @exception rb_eArgError Multiplication could integer overflow. * @return `x` * `y`. * * @internal * * This is in fact also an implementation detail of ruby_xmalloc2() etc. / static inline size_t rbimpl_size_mul_or_raise(size_t x, size_t y) { struct rbimpl_size_mul_overflow_tag size = rbimpl_size_mul_overflow(x, y); if (RB_LIKELY(! size.left)) { return size.right; } else { ruby_malloc_size_overflow(x, y); RBIMPL_UNREACHABLE_RETURN(0); } } /* * This is an implementation detail of #RB_ALLOCV_N(). People don't use this * directly. * * @param[out] store Pointer to a variable. * @param[in] count Number of elements in an array. * @param[in] elsize Size of each elements. * @return Region of `count` * `elsize` bytes. * @post `store` holds the corresponding tmp buffer object. * * @internal * * We might want to deprecate this function and make a `rbimpl_` counterpart. / static inline void rb_alloc_tmp_buffer2(volatile VALUE store, long count, size_t elsize) { const size_t total_size = rbimpl_size_mul_or_raise(count, elsize); const size_t cnt = (total_size + sizeof(VALUE) - 1) / sizeof(VALUE); return rb_alloc_tmp_buffer_with_count(store, total_size, cnt); } #if ! defined(__MINGW32__) && ! defined(__DOXYGEN__) RBIMPL_SYMBOL_EXPORT_BEGIN() RBIMPL_ATTR_NOALIAS() RBIMPL_ATTR_NONNULL((1)) RBIMPL_ATTR_RETURNS_NONNULL() / At least since 2004, glibc's <string.h> annotates memcpy to be * __attribute__((__nonnull__(1, 2))). However it is safe to pass NULL to the * source pointer, if n is 0. Let's wrap memcpy. / static inline void ruby_nonempty_memcpy(void dest, const void src, size_t n) { if (n) { return memcpy(dest, src, n); } else { return dest; } } RBIMPL_SYMBOL_EXPORT_END() #undef memcpy #define memcpy ruby_nonempty_memcpy #endif #endif /* RBIMPL_MEMORY_H */ Back

Edit File : memory.h | Size : 23.13 KB

#ifndef RBIMPL_MEMORY_H                              /*-*-C++-*-vi:se ft=cpp:*/
#define RBIMPL_MEMORY_H
/**
 * @file
 * @author     Ruby developers <ruby-core@ruby-lang.org>
 * @copyright  This  file  is   a  part  of  the   programming  language  Ruby.
 *             Permission  is hereby  granted,  to  either redistribute  and/or
 *             modify this file, provided that  the conditions mentioned in the
 *             file COPYING are met.  Consult the file for details.
 * @warning    Symbols   prefixed  with   either  `RBIMPL`   or  `rbimpl`   are
 *             implementation details.   Don't take  them as canon.  They could
 *             rapidly appear then vanish.  The name (path) of this header file
 *             is also an  implementation detail.  Do not expect  it to persist
 *             at the place it is now.  Developers are free to move it anywhere
 *             anytime at will.
 * @note       To  ruby-core:  remember  that   this  header  can  be  possibly
 *             recursively included  from extension  libraries written  in C++.
 *             Do not  expect for  instance `__VA_ARGS__` is  always available.
 *             We assume C99  for ruby itself but we don't  assume languages of
 *             extension libraries.  They could be written in C++98.
 * @brief      Memory management stuff.
 */
#include "ruby/internal/config.h"

#ifdef STDC_HEADERS
# include <stddef.h>
#endif

#ifdef HAVE_STRING_H
# include <string.h>
#endif

#ifdef HAVE_STDINT_H
# include <stdint.h>
#endif

#ifdef HAVE_ALLOCA_H
# include <alloca.h>
#endif

#if defined(_MSC_VER) && defined(_WIN64)
# include <intrin.h>
# pragma intrinsic(_umul128)
#endif

#include "ruby/internal/attr/alloc_size.h"
#include "ruby/internal/attr/const.h"
#include "ruby/internal/attr/constexpr.h"
#include "ruby/internal/attr/noalias.h"
#include "ruby/internal/attr/nonnull.h"
#include "ruby/internal/attr/noreturn.h"
#include "ruby/internal/attr/restrict.h"
#include "ruby/internal/attr/returns_nonnull.h"
#include "ruby/internal/cast.h"
#include "ruby/internal/dllexport.h"
#include "ruby/internal/has/builtin.h"
#include "ruby/internal/stdalign.h"
#include "ruby/internal/stdbool.h"
#include "ruby/internal/xmalloc.h"
#include "ruby/backward/2/limits.h"
#include "ruby/backward/2/long_long.h"
#include "ruby/backward/2/assume.h"
#include "ruby/defines.h"

/** @cond INTENAL_MACRO  */

/* Make alloca work the best possible way.  */
#if defined(alloca)
# /* Take that. */
#elif RBIMPL_HAS_BUILTIN(__builtin_alloca)
# define alloca __builtin_alloca
#elif defined(_AIX)
# pragma alloca
#elif defined(__cplusplus)
extern "C" void *alloca(size_t);
#else
extern void *alloca();
#endif

/** @endcond  */

#if defined(__DOXYGEN__)
/**
 * @private
 *
 * Type that is as twice wider as  size_t.  This is an implementation detail of
 * rb_mul_size_overflow().  People should not use it.   This is not a good name
 * either.
 */
typedef uint128_t DSIZE_T;
#elif defined(HAVE_INT128_T) && SIZEOF_SIZE_T <= 8
# define DSIZE_T uint128_t
#elif SIZEOF_SIZE_T * 2 <= SIZEOF_LONG_LONG
# define DSIZE_T unsigned LONG_LONG
#endif

/**
 * @private
 *
 * Maximum  possible  number  of  bytes  that  #RB_ALLOCV  can  allocate  using
 * `alloca`.  Anything  beyond this  is allocated  using rb_alloc_tmp_buffer().
 * This selection is transparent to users.  People don't have to bother.
 */
#ifdef C_ALLOCA
# define RUBY_ALLOCV_LIMIT 0
#else
# define RUBY_ALLOCV_LIMIT 1024
#endif

/**
 * Prevents premature  destruction of local objects.   Ruby's garbage collector
 * is conservative; it  scans the C level machine stack  as well.  Possible in-
 * use Ruby  objects must  remain visible  on stack, to  be properly  marked as
 * such.  However  contemporary C  compilers do not  interface well  with this.
 * Consider the following example:
 *
 * ```CXX
 * auto s = rb_str_new_cstr(" world");
 * auto sptr = RSTRING_PTR(s);
 * auto t = rb_str_new_cstr("hello,"); // Possible GC invocation
 * auto u = rb_str_cat_cstr(t, sptr);
 *
 * RB_GC_GUARD(s); // ensure `s` (and thus `sptr`) do not get GC-ed
 * ```
 *
 * Here, without the #RB_GC_GUARD, the last use of `s` is _before_ the last use
 * of `sptr`.  Compilers  could thus think `s` and `t`  are allowed to overlap.
 * That would eliminate `s`  from the stack, while `sptr` is  still in use.  If
 * our GC  ran at  that very moment,  `s` gets swept  out, which  also destroys
 * `sptr`.  Boom!  You got a SEGV.
 *
 * In order  to prevent this scenario  #RB_GC_GUARD must be placed  _after_ the
 * last use of `sptr`.  Placing  #RB_GC_GUARD before dereferencing `sptr` would
 * be of no use.
 *
 * #RB_GC_GUARD would  not be  necessary at  all in the  above example  if non-
 * inlined  function  calls are  made  on  the  `s`  variable after  `sptr`  is
 * dereferenced.  Thus, in  the above example, calling  any un-inlined function
 * on `s`  such as `rb_str_modify(s);`  will ensure `s`  stays on the  stack or
 * register to prevent a GC invocation from prematurely freeing it.
 *
 * Using the #RB_GC_GUARD  macro is preferable to using  the `volatile` keyword
 * in C.  #RB_GC_GUARD has the following advantages:
 *
 *  - the intent of the macro use is clear.
 *
 *  - #RB_GC_GUARD only affects its call  site.  OTOH `volatile` generates some
 *    extra code every time the variable is used, hurting optimisation.
 *
 *  - `volatile` implementations  may be  buggy/inconsistent in  some compilers
 *    and   architectures.     #RB_GC_GUARD   is   customisable    for   broken
 *    systems/compilers without negatively affecting other systems.
 *
 *  - C++  since C++20  deprecates  `volatile`.  If  you  write your  extension
 *    library in that language there is no escape but to use this macro.
 *
 * @param  v  A variable of ::VALUE type.
 * @post   `v` is still alive.
 */
#ifdef __GNUC__
#define RB_GC_GUARD(v) \
    (*__extension__ ({ \
        volatile VALUE *rb_gc_guarded_ptr = &(v); \
        __asm__("" : : "m"(rb_gc_guarded_ptr)); \
        rb_gc_guarded_ptr; \
    }))
#elif defined _MSC_VER
#define RB_GC_GUARD(v) (*rb_gc_guarded_ptr(&(v)))
#else
#define HAVE_RB_GC_GUARDED_PTR_VAL 1
#define RB_GC_GUARD(v) (*rb_gc_guarded_ptr_val(&(v),(v)))
#endif

/* Casts needed because void* is NOT compatible with others in C++. */

/**
 * Convenient macro that allocates an array of n elements.
 *
 * @param      type            Type of array elements.
 * @param      n               Length of the array.
 * @exception  rb_eNoMemError  No space left for allocation.
 * @exception  rb_eArgError    Integer overflow trying  to calculate the length
 *                             of continuous  memory region of `n`  elements of
 *                             `type`.
 * @return     Storage  instance  that  is  capable of  storing  at  least  `n`
 *             elements of type `type`.
 * @note       It doesn't return NULL, even when `n` is zero.
 * @warning    The return  value shall  be invalidated  exactly once  by either
 *             ruby_xfree(),  ruby_xrealloc(), or  ruby_xrealloc2().   It is  a
 *             failure to pass it to system free(), because the system and Ruby
 *             might or might not share the same malloc() implementation.
 */
#define RB_ALLOC_N(type,n)  RBIMPL_CAST((type *)ruby_xmalloc2((n), sizeof(type)))

/**
 * Shorthand of #RB_ALLOC_N with `n=1`.
 *
 * @param      type            Type of allocation.
 * @exception  rb_eNoMemError  No space left for allocation.
 * @return     Storage instance that can hold an `type` object.
 * @note       It doesn't return NULL.
 * @warning    The return  value shall  be invalidated  exactly once  by either
 *             ruby_xfree(),  ruby_xrealloc(), or  ruby_xrealloc2().   It is  a
 *             failure to pass it to system free(), because the system and Ruby
 *             might or might not share the same malloc() implementation.
 */
#define RB_ALLOC(type)      RBIMPL_CAST((type *)ruby_xmalloc(sizeof(type)))

/**
 * Identical to  #RB_ALLOC_N() but also  nullifies the allocated  region before
 * returning.
 *
 * @param      type            Type of array elements.
 * @param      n               Length of the array.
 * @exception  rb_eNoMemError  No space left for allocation.
 * @exception  rb_eArgError    Integer overflow trying  to calculate the length
 *                             of continuous  memory region of `n`  elements of
 *                             `type`.
 * @return     Storage  instance  that  is  capable of  storing  at  least  `n`
 *             elements of type `type`.
 * @post       Returned array is filled with zeros.
 * @note       It doesn't return NULL, even when `n` is zero.
 * @warning    The return  value shall  be invalidated  exactly once  by either
 *             ruby_xfree(),  ruby_xrealloc(), or  ruby_xrealloc2().   It is  a
 *             failure to pass it to system free(), because the system and Ruby
 *             might or might not share the same malloc() implementation.
 */
#define RB_ZALLOC_N(type,n) RBIMPL_CAST((type *)ruby_xcalloc((n), sizeof(type)))

/**
 * Shorthand of #RB_ZALLOC_N with `n=1`.
 *
 * @param      type            Type of allocation.
 * @exception  rb_eNoMemError  No space left for allocation.
 * @return     Storage instance that can hold an `type` object.
 * @post       Returned object is filled with zeros.
 * @note       It doesn't return NULL.
 * @warning    The return  value shall  be invalidated  exactly once  by either
 *             ruby_xfree(),  ruby_xrealloc(), or  ruby_xrealloc2().   It is  a
 *             failure to pass it to system free(), because the system and Ruby
 *             might or might not share the same malloc() implementation.
 */
#define RB_ZALLOC(type)     (RB_ZALLOC_N(type, 1))

/**
 * Convenient macro that reallocates an array with a new size.
 *
 * @param      var             A variable of `type`,  which points to a storage
 *                             instance  that  was   previously  returned  from
 *                             either
 *                               - ruby_xmalloc(),
 *                               - ruby_xmalloc2(),
 *                               - ruby_xcalloc(),
 *                               - ruby_xrealloc(), or
 *                               - ruby_xrealloc2().
 * @param      type            Type of allocation.
 * @param      n               Requested new size of each element.
 * @exception  rb_eNoMemError  No space left for  allocation.
 * @exception  rb_eArgError    Integer overflow trying  to calculate the length
 *                             of continuous  memory region of `n`  elements of
 *                             `type`.
 * @return     Storage  instance  that  is  capable of  storing  at  least  `n`
 *             elements of type `type`.
 * @pre        The passed variable must point to a valid live storage instance.
 *             It is a  failure to pass a variable that  holds an already-freed
 *             pointer.
 * @note       It doesn't return NULL, even when `n` is zero.
 * @warning    Do not  assume anything  on the alignment  of the  return value.
 *             There is  no guarantee  that it  inherits the  passed argument's
 *             one.
 * @warning    The return  value shall  be invalidated  exactly once  by either
 *             ruby_xfree(),  ruby_xrealloc(), or  ruby_xrealloc2().   It is  a
 *             failure to pass it to system free(), because the system and Ruby
 *             might or might not share the same malloc() implementation.
 */
#define RB_REALLOC_N(var,type,n) \
    ((var) = RBIMPL_CAST((type *)ruby_xrealloc2((void *)(var), (n), sizeof(type))))

/**
 * @deprecated  This  macro is  dangerous (does  not bother  stack overflow  at
 *              all).  #RB_ALLOCV is the modern way to do the same thing.
 * @param       type  Type of array elements.
 * @param       n     Length of the array.
 * @return      A pointer on stack.
 */
#define ALLOCA_N(type,n) \
    RBIMPL_CAST((type *)alloca(rbimpl_size_mul_or_raise(sizeof(type), (n))))

/**
 * Identical to #RB_ALLOCV_N(), except it  implicitly assumes the type of array
 * is ::VALUE.
 *
 * @param   v  A variable to hold the just-in-case opaque Ruby object.
 * @param   n  Size of allocation, in bytes.
 * @return  An array of `n` bytes of ::VALUE.
 * @note    `n` may be evaluated twice.
 */
#define RB_ALLOCV(v, n)        \
    ((n) < RUBY_ALLOCV_LIMIT ? \
     ((v) = 0, alloca(n)) :    \
     rb_alloc_tmp_buffer(&(v), (n)))

/**
 * Allocates a  memory region, possibly  on stack.   If the given  size exceeds
 * #RUBY_ALLOCV_LIMIT, it allocates a dedicated  opaque ruby object instead and
 * let our GC sweep that region after use.  Either way you can fire-and-forget.
 *
 * ```CXX
 * #include <sys/types.h>
 *
 * VALUE
 * foo(int n)
 * {
 *     VALUE v;
 *     auto ptr = RB_ALLOCV(struct tms, v, n);
 *     ...
 *     // no need to free `ptr`.
 * }
 * ```
 *
 * If you want to  be super-duper polite you can also  explicitly state the end
 * of use of such memory region by calling #RB_ALLOCV_END().
 *
 * @param   type  The type of array elements.
 * @param   v     A variable to hold the just-in-case opaque Ruby object.
 * @param   n     Number of elements requested to allocate.
 * @return  An array of `n` elements of `type`.
 * @note    `n` may be evaluated twice.
 */
#define RB_ALLOCV_N(type, v, n)                             \
    RBIMPL_CAST((type *)                                     \
        (((size_t)(n) < RUBY_ALLOCV_LIMIT / sizeof(type)) ? \
         ((v) = 0, alloca((n) * sizeof(type))) :            \
         rb_alloc_tmp_buffer2(&(v), (n), sizeof(type))))

/**
 * Polite way to declare that the given  array is not used any longer.  Calling
 * this not mandatory.  Our GC can baby-sit  you.  However it is not a very bad
 * idea to use it when possible.  Doing so could reduce memory footprint.
 *
 * @param  v  A variable previously passed to either #RB_ALLOCV/#RB_ALLOCV_N.
 */
#define RB_ALLOCV_END(v) rb_free_tmp_buffer(&(v))

/**
 * Handy macro to erase a region of memory.
 *
 * @param   p     Target pointer.
 * @param   type  Type of `p[0]`
 * @param   n     Length of `p`.
 * @return  `p`.
 * @post    First `n` elements of `p` are squashed.
 */
#define MEMZERO(p,type,n) memset((p), 0, rbimpl_size_mul_or_raise(sizeof(type), (n)))

/**
 * Handy macro to call memcpy.
 *
 * @param   p1    Destination pointer.
 * @param   p2    Source pointer.
 * @param   type  Type of `p2[0]`
 * @param   n     Length of `p2`.
 * @return  `p1`.
 * @post    First `n` elements of `p2` are copied into `p1`.
 */
#define MEMCPY(p1,p2,type,n) memcpy((p1), (p2), rbimpl_size_mul_or_raise(sizeof(type), (n)))

/**
 * Handy macro to call memmove.
 *
 * @param  p1    Destination pointer.
 * @param  p2    Source pointer.
 * @param  type  Type of `p2[0]`
 * @param  n     Length of `p2`.
 * @return `p1`.
 * @post   First `n` elements of `p2` are copied into `p1`.
 */
#define MEMMOVE(p1,p2,type,n) memmove((p1), (p2), rbimpl_size_mul_or_raise(sizeof(type), (n)))

/**
 * Handy macro to call memcmp
 *
 * @param   p1    Target LHS.
 * @param   p2    Target RHS.
 * @param   type  Type of `p1[0]`
 * @param   n     Length of `p1`.
 * @retval  <0    `p1` is "less" than `p2`.
 * @retval  0     `p1` is equal to `p2`.
 * @retval  >0    `p1` is "greater" than `p2`.
 */
#define MEMCMP(p1,p2,type,n) memcmp((p1), (p2), rbimpl_size_mul_or_raise(sizeof(type), (n)))

#define ALLOC_N    RB_ALLOC_N    /**< @old{RB_ALLOC_N} */
#define ALLOC      RB_ALLOC      /**< @old{RB_ALLOC} */
#define ZALLOC_N   RB_ZALLOC_N   /**< @old{RB_ZALLOC_N} */
#define ZALLOC     RB_ZALLOC     /**< @old{RB_ZALLOC} */
#define REALLOC_N  RB_REALLOC_N  /**< @old{RB_REALLOC_N} */
#define ALLOCV     RB_ALLOCV     /**< @old{RB_ALLOCV} */
#define ALLOCV_N   RB_ALLOCV_N   /**< @old{RB_ALLOCV_N} */
#define ALLOCV_END RB_ALLOCV_END /**< @old{RB_ALLOCV_END} */

/**
 * @private
 *
 * This is an implementation detail of rbimpl_size_mul_overflow().
 *
 * @internal
 *
 * Expecting  this struct  to be  eliminated  by function  inlinings.  This  is
 * nothing more than std::variant<std::size_t> if  we could use recent C++, but
 * reality is we cannot.
 */
struct rbimpl_size_mul_overflow_tag {
    bool left;                  /**< Whether overflow happened or not. */
    size_t right;               /**< Multiplication result. */
};

RBIMPL_SYMBOL_EXPORT_BEGIN()
RBIMPL_ATTR_RESTRICT()
RBIMPL_ATTR_RETURNS_NONNULL()
RBIMPL_ATTR_ALLOC_SIZE((2))
RBIMPL_ATTR_NONNULL(())
/**
 * @private
 *
 * This is  an implementation  detail of #RB_ALLOCV().   People don't  use this
 * directly.
 *
 * @param[out]  store  Pointer to a variable.
 * @param[in]   len    Requested number of bytes to allocate.
 * @return      Allocated `len` bytes array.
 * @post        `store` holds the corresponding tmp buffer object.
 */
void *rb_alloc_tmp_buffer(volatile VALUE *store, long len);

RBIMPL_ATTR_RESTRICT()
RBIMPL_ATTR_RETURNS_NONNULL()
RBIMPL_ATTR_ALLOC_SIZE((2,3))
RBIMPL_ATTR_NONNULL(())
/**
 * @private
 *
 * This is an  implementation detail of #RB_ALLOCV_N().  People  don't use this
 * directly.
 *
 * @param[out]  store  Pointer to a variable.
 * @param[in]   len    Requested number of bytes to allocate.
 * @param[in]   count  Number of elements in an array.
 * @return      Allocated `len` bytes array.
 * @post        `store` holds the corresponding tmp buffer object.
 *
 * @internal
 *
 * Although  the  meaning  of  `count` variable  is  clear,  @shyouhei  doesn't
 * understand its needs.
 */
void *rb_alloc_tmp_buffer_with_count(volatile VALUE *store, size_t len,size_t count);

/**
 * @private
 *
 * This is an implementation detail of #RB_ALLOCV_END().  People don't use this
 * directly.
 *
 * @param[out]  store  Pointer to a variable.
 * @pre         `store` is a NULL, or a pointer to a tmp buffer object.
 * @post        `*store` is ::RUBY_Qfalse.
 * @post        The object formerly stored in `store` is destroyed.
 */
void rb_free_tmp_buffer(volatile VALUE *store);

RBIMPL_ATTR_NORETURN()
/**
 * @private
 *
 * This is an  implementation detail of #RB_ALLOCV_N().  People  don't use this
 * directly.
 *
 * @param[in]  x             Arbitrary value.
 * @param[in]  y             Arbitrary value.
 * @exception  rb_eArgError  `x` * `y` would integer overflow.
 */
void ruby_malloc_size_overflow(size_t x, size_t y);

#ifdef HAVE_RB_GC_GUARDED_PTR_VAL
volatile VALUE *rb_gc_guarded_ptr_val(volatile VALUE *ptr, VALUE val);
#endif
RBIMPL_SYMBOL_EXPORT_END()

#ifdef _MSC_VER
# pragma optimize("", off)

/**
 * @private
 *
 * This is an  implementation detail of #RB_GC_GUARD().  People  don't use this
 * directly.
 *
 * @param[in]  ptr  A pointer to an on-stack C variable.
 * @return     `ptr` as-is.
 */
static inline volatile VALUE *
rb_gc_guarded_ptr(volatile VALUE *ptr)
{
    return ptr;
}

# pragma optimize("", on)
#endif

/**
 * @deprecated  This   function   was   an   implementation   detail   of   old
 *              #RB_ALLOCV_N().  We no longer  use it.  @shyouhei suspects that
 *              there are  no actual usage now.   However it was not  marked as
 *              private before.  We cannot delete it any longer.
 * @param[in]   a    Arbitrary value.
 * @param[in]   b    Arbitrary value.
 * @param[in]   max  Possible maximum value.
 * @param[out]  c    A pointer to return the computation result.
 * @retval      1    `c` is insane.
 * @retval      0    `c` is sane.
 * @post        `c` holds `a` * `b`, but could be overflowed.
 */
static inline int
rb_mul_size_overflow(size_t a, size_t b, size_t max, size_t *c)
{
#ifdef DSIZE_T
    RB_GNUC_EXTENSION DSIZE_T da, db, c2;
    da = a;
    db = b;
    c2 = da * db;
    if (c2 > max) return 1;
    *c = RBIMPL_CAST((size_t)c2);
#else
    if (b != 0 && a > max / b) return 1;
    *c = a * b;
#endif
    return 0;
}

#if defined(__DOXYGEN__)
RBIMPL_ATTR_CONSTEXPR(CXX14)
#elif RBIMPL_COMPILER_SINCE(GCC, 7, 0, 0)
RBIMPL_ATTR_CONSTEXPR(CXX14) /* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70507 */
#elif RBIMPL_COMPILER_SINCE(Clang, 7, 0, 0)
RBIMPL_ATTR_CONSTEXPR(CXX14) /* https://bugs.llvm.org/show_bug.cgi?id=37633 */
#endif
RBIMPL_ATTR_CONST()
/**
 * @private
 *
 * This is an  implementation detail of #RB_ALLOCV_N().  People  don't use this
 * directly.
 *
 * @param[in]  x  Arbitrary value.
 * @param[in]  y  Arbitrary value.
 * @return     `{ left, right }`,  where `left` is whether there  is an integer
 *             overflow or not,  and `right` is a  (possibly overflowed) result
 *             of `x` * `y`.
 *
 * @internal
 *
 * This is in fact also an implementation detail of ruby_xmalloc2() etc.
 */
static inline struct rbimpl_size_mul_overflow_tag
rbimpl_size_mul_overflow(size_t x, size_t y)
{
    struct rbimpl_size_mul_overflow_tag ret = { false,  0, };

#if RBIMPL_HAS_BUILTIN(__builtin_mul_overflow)
    ret.left = __builtin_mul_overflow(x, y, &ret.right);

#elif defined(DSIZE_T)
    RB_GNUC_EXTENSION DSIZE_T dx = x;
    RB_GNUC_EXTENSION DSIZE_T dy = y;
    RB_GNUC_EXTENSION DSIZE_T dz = dx * dy;
    ret.left  = dz > SIZE_MAX;
    ret.right = RBIMPL_CAST((size_t)dz);

#elif defined(_MSC_VER) && defined(_WIN64)
    unsigned __int64 dp = 0;
    unsigned __int64 dz = _umul128(x, y, &dp);
    ret.left  = RBIMPL_CAST((bool)dp);
    ret.right = RBIMPL_CAST((size_t)dz);

#else
    /* https://wiki.sei.cmu.edu/confluence/display/c/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap */
    ret.left  = (y != 0) && (x > SIZE_MAX / y);
    ret.right = x * y;
#endif

return ret;
}

/**
 * @private
 *
 * This is an  implementation detail of #RB_ALLOCV_N().  People  don't use this
 * directly.
 *
 * @param[in]  x             Arbitrary value.
 * @param[in]  y             Arbitrary value.
 * @exception  rb_eArgError  Multiplication could integer overflow.
 * @return     `x` * `y`.
 *
 * @internal
 *
 * This is in fact also an implementation detail of ruby_xmalloc2() etc.
 */
static inline size_t
rbimpl_size_mul_or_raise(size_t x, size_t y)
{
    struct rbimpl_size_mul_overflow_tag size =
        rbimpl_size_mul_overflow(x, y);

if (RB_LIKELY(! size.left)) {
        return size.right;
    }
    else {
        ruby_malloc_size_overflow(x, y);
        RBIMPL_UNREACHABLE_RETURN(0);
    }
}

/**
 * This is an  implementation detail of #RB_ALLOCV_N().  People  don't use this
 * directly.
 *
 * @param[out]  store   Pointer to a variable.
 * @param[in]   count   Number of elements in an array.
 * @param[in]   elsize  Size of each elements.
 * @return      Region of `count` * `elsize` bytes.
 * @post        `store` holds the corresponding tmp buffer object.
 *
 * @internal
 *
 * We might want to deprecate this function and make a `rbimpl_` counterpart.
 */
static inline void *
rb_alloc_tmp_buffer2(volatile VALUE *store, long count, size_t elsize)
{
    const size_t total_size = rbimpl_size_mul_or_raise(count, elsize);
    const size_t cnt = (total_size + sizeof(VALUE) - 1) / sizeof(VALUE);
    return rb_alloc_tmp_buffer_with_count(store, total_size, cnt);
}

#if ! defined(__MINGW32__) && ! defined(__DOXYGEN__)
RBIMPL_SYMBOL_EXPORT_BEGIN()
RBIMPL_ATTR_NOALIAS()
RBIMPL_ATTR_NONNULL((1))
RBIMPL_ATTR_RETURNS_NONNULL()
/* At least since 2004, glibc's <string.h> annotates memcpy to be
 * __attribute__((__nonnull__(1, 2))).  However it is safe to pass NULL to the
 * source pointer, if n is 0.  Let's wrap memcpy. */
static inline void *
ruby_nonempty_memcpy(void *dest, const void *src, size_t n)
{
    if (n) {
        return memcpy(dest, src, n);
    }
    else {
        return dest;
    }
}
RBIMPL_SYMBOL_EXPORT_END()
#undef memcpy
#define memcpy ruby_nonempty_memcpy
#endif

#endif /* RBIMPL_MEMORY_H */

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