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pie: provide memcpy/memcmp/memset for noglibc case

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Use alias function attribute to provide memcpy(), memcmp()
and memset() in case we're not linking with libc. This is
needed as compiler can generate calls to those functions
(clang actually does that).

[v2: add comment, move aliases to under HAS_BUILTIN_*]

https://travis-ci.org/kolyshkin/criu/builds/174634847
Idea-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
This commit is contained in:
Kir Kolyshkin
2016-11-10 16:32:27 -08:00
committed by Pavel Emelyanov
parent f845d9e4e0
commit bdf60512de
1 changed files with 23 additions and 3 deletions
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26
criu/include/asm-generic/string.h
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@@ -3,8 +3,16 @@
#include "common/compiler.h"
/* C compiler may generate calls to memcmp, memset, memcpy and memmove,
* so it relies on those to be available during linking.
* In case we are not linking our code against glibc, we set CR_NOGLIBC
* and have to provide our own implementations of mem*() functions.
*
* For now, not having memmove() seems OK for both gcc and clang.
*/
#ifndef HAS_BUILTIN_MEMCPY
static always_inline void *builtin_memcpy(void *to, const void *from, size_t n)
static __maybe_unused void *builtin_memcpy(void *to, const void *from, size_t n)
{
size_t i;
unsigned char *cto = to;
@@ -16,10 +24,14 @@ static always_inline void *builtin_memcpy(void *to, const void *from, size_t n)
return to;
}
#ifdef CR_NOGLIBC
void *memcpy(void *to, const void *from, size_t n) \
__attribute__ ((weak, alias ("builtin_memcpy")));
#endif
#endif
#ifndef HAS_BUILTIN_MEMCMP
static always_inline int builtin_memcmp(const void *cs, const void *ct, size_t count)
static __maybe_unused int builtin_memcmp(const void *cs, const void *ct, size_t count)
{
const unsigned char *su1, *su2;
int res = 0;
@@ -29,6 +41,10 @@ static always_inline int builtin_memcmp(const void *cs, const void *ct, size_t c
break;
return res;
}
#ifdef CR_NOGLIBC
int memcmp(const void *cs, const void *ct, size_t count) \
__attribute__ ((weak, alias ("builtin_memcmp")));
#endif
#endif
#ifndef HAS_BUILTIN_STRNCMP
@@ -47,7 +63,7 @@ static always_inline int builtin_strncmp(const char *cs, const char *ct, size_t
#endif
#ifndef HAS_BUILTIN_MEMSET
static always_inline void *builtin_memset(void *s, const int c, size_t count)
static __maybe_unused void *builtin_memset(void *s, const int c, size_t count)
{
char *dest = s;
size_t i = 0;
@@ -57,6 +73,10 @@ static always_inline void *builtin_memset(void *s, const int c, size_t count)
return s;
}
#ifdef CR_NOGLIBC
void *memset(void *s, const int c, size_t count) \
__attribute__ ((weak, alias ("builtin_memset")));
#endif
#endif
#endif /* __CR_ASM_GENERIC_STRING_H__ */