memcpy -
メモリー領域をコピーする。
#include <string.h>
void *memcpy(void *dest, const void *src, size_t n);
memcpy() はメモリー領域
src の先頭
n バイトを
メモリー領域
dest
にコピーする。コピー元の領域と
コピー先の領域が重なってはならない。重なっている場合は
memmove(3) を使うこと。
memcpy() は
dest
へのポインターを返す。
この節で使用されている用語の説明については、
attributes(7) を参照。
| インターフェース |
属性 |
値 |
|
memcpy() |
Thread safety |
MT-Safe |
POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.
Failure to observe the requirement that the memory areas do not overlap has been
the source of significant bugs. (POSIX and the C standards are explicit that
employing
memcpy() with overlapping areas produces undefined behavior.)
Most notably, in glibc 2.13 a performance optimization of
memcpy() on
some platforms (including x86-64) included changing the order in which bytes
were copied from
src to
dest.
This change revealed breakages in a number of applications that performed
copying with overlapping areas. Under the previous implementation, the order
in which the bytes were copied had fortuitously hidden the bug, which was
revealed when the copying order was reversed. In glibc 2.14, a versioned
symbol was added so that old binaries (i.e., those linked against glibc
versions earlier than 2.14) employed a
memcpy() implementation that
safely handles the overlapping buffers case (by providing an "older"
memcpy() implementation that was aliased to
memmove(3)).
bcopy(3),
bstring(3),
memccpy(3),
memmove(3),
mempcpy(3),
strcpy(3),
strncpy(3),
wmemcpy(3)
この man ページは Linux
man-pages
プロジェクトのリリース
5.10
の一部である。プロジェクトの説明とバグ報告に関する情報は
https://www.kernel.org/doc/man-pages/
に書かれている。