From: "alx (Alejandro Colomar)" Date: 2022-07-06T22:32:49+00:00 Subject: [ruby-core:109155] [Ruby master Bug#18893] Don't redefine memcpy(3) Issue #18893 has been updated by alx (Alejandro Colomar). shyouhei (Shyouhei Urabe) wrote in #note-8: > This is my take: > > ```patch > From 505d00311d82fdbed80688e9db792c3b54b8ee27 Mon Sep 17 00:00:00 2001 > From: =?UTF-8?q?=E5=8D=9C=E9=83=A8=E6=98=8C=E5=B9=B3?= > > Date: Wed, 6 Jul 2022 09:18:28 +0900 > Subject: [PATCH] do not define our own version of memcpy > > The (sole) use of memcpy in our public header is now replaced to > directly call ruby_nonempty_memcpy, and the previous definition of > memcpy is now internal-only. > --- > include/ruby/internal/memory.h | 6 +----- > internal.h | 3 +++ > 2 files changed, 4 insertions(+), 5 deletions(-) > > diff --git a/include/ruby/internal/memory.h b/include/ruby/internal/memory.h > index aa3464465d..0f59262a91 100644 > --- a/include/ruby/internal/memory.h > +++ b/include/ruby/internal/memory.h > @@ -363,7 +363,7 @@ typedef uint128_t DSIZE_T; > * @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))) > +#define MEMCPY(p1,p2,type,n) ruby_nonempty_memcpy((p1), (p2), rbimpl_size_mul_or_raise(sizeof(type), (n))) > > /** > * Handy macro to call memmove. > @@ -644,7 +644,6 @@ rb_alloc_tmp_buffer2(volatile VALUE *store, long count, size_t elsize) > 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)) > @@ -663,8 +662,5 @@ ruby_nonempty_memcpy(void *dest, const void *src, size_t n) > } > } > RBIMPL_SYMBOL_EXPORT_END() > -#undef memcpy > -#define memcpy ruby_nonempty_memcpy > -#endif > > #endif /* RBIMPL_MEMORY_H */ > diff --git a/internal.h b/internal.h > index 00a8295295..7e1abcbab8 100644 > --- a/internal.h > +++ b/internal.h > @@ -106,4 +106,7 @@ RUBY_SYMBOL_EXPORT_END > #define RBOOL(v) ((v) ? Qtrue : Qfalse) > #define RB_BIGNUM_TYPE_P(x) RB_TYPE_P((x), T_BIGNUM) > > +#ifndef __MINGW32__ > +#define memcpy ruby_nonempty_memcpy Is this header something that's not installed in the system? Otherwise, the problem would remain I guess. If it's not installed, it makes sense (it would not define memcyp(3) for others. Thanks, Alex > +#endif > #endif /* RUBY_INTERNAL_H */ > -- > 2.17.1 > > ``` ---------------------------------------- Bug #18893: Don't redefine memcpy(3) https://bugs.ruby-lang.org/issues/18893#change-98298 * Author: alx (Alejandro Colomar) * Status: Open * Priority: Normal * Assignee: shyouhei (Shyouhei Urabe) * ruby -v: ruby 3.0.4p208 (2022-04-12 revision 3fa771dded) [x86_64-linux-gnu] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- It is Undefined Behavior, by any standard ever issued. See what I have in my system right now: ``` alx@asus5775:/usr/include$ grepc memcpy ./string.h:43: extern void *memcpy (void *__restrict __dest, const void *__restrict __src, size_t __n) __THROW __nonnull ((1, 2)); ./x86_64-linux-gnu/ruby-3.0.0/rb_mjit_min_header-3.0.4.h:1520: extern void *memcpy (void *__restrict __dest, const void *__restrict __src, size_t __n) __attribute__ ((__nothrow__ , __leaf__)) __attribute__ ((__nonnull__ (1, 2))); ./x86_64-linux-gnu/ruby-3.0.0/rb_mjit_min_header-3.0.4.h:1670: extern __inline __attribute__ ((__always_inline__)) __attribute__ ((__gnu_inline__)) __attribute__ ((__artificial__)) void * __attribute__ ((__nothrow__ , __leaf__)) memcpy (void *__restrict __dest, const void *__restrict __src, size_t __len) { return __builtin___memcpy_chk (__dest, __src, __len, __builtin_object_size (__dest, 0)); } ./ruby-3.0.0/ruby/internal/memory.h:278: #define memcpy ruby_nonempty_memcpy ./x86_64-linux-gnu/ruby-3.0.0/rb_mjit_min_header-3.0.4.h:22679: #define memcpy ruby_nonempty_memcpy $ grepc ruby_nonempty_memcpy ./ruby-3.0.0/ruby/internal/memory.h:266: static inline void * ruby_nonempty_memcpy(void *dest, const void *src, size_t n) { if (n) { return memcpy(dest, src, n); } else { return dest; } } ./x86_64-linux-gnu/ruby-3.0.0/rb_mjit_min_header-3.0.4.h:5673: __attribute__((__nonnull__ (1))) __attribute__((__returns_nonnull__)) static inline void * ruby_nonempty_memcpy(void *dest, const void *src, size_t n) { if (n) { return memcpy(dest, src, n); } else { return dest; } } ``` Some code that I maintain includes some ruby headers, which end up defining memcpy(3) to that thing. Then, my code calls memcpy(3) from a function, which happens to be inline (yes, inline, not static inline, which is a horrible thing), and I get an error from the compiler, for using a static function within a non-static inline function. So, I'd like you to please remove that definition from public headers, and refrain from redefining any ISO C functions. If not, please define it to something not broken (and yes, static inline is broken, as it produces duplicated code when not inlined; you could use [[gnu::always_inline]] if you want to keep static, but don't). Just C99 inline would be reasonable. See also: Thanks, Alex -- https://bugs.ruby-lang.org/ Unsubscribe: