thevar1able/ClickHouse
1
0
Fork 0
mirror of https://github.com/ClickHouse/ClickHouse.git synced 2024-11-10 01:25:21 +00:00
Code Issues Packages Projects Releases Wiki Activity

__auxv_init lazy initialization

Browse Source
This commit is contained in:
Vitaly Baranov 2021-08-12 11:05:27 +02:00 committed by Mikhail Filimonov
parent 2c01e2789a
commit 242d8e1861
No known key found for this signature in database
GPG Key ID: 6E49C2E9AF1220BE
1 changed files with 28 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
base/glibc-compatibility/musl/getauxval.c
View File

@ -1,4 +1,5 @@
#include <sys/auxv.h>
#include "atomic.h"
#include <unistd.h> // __environ
#include <errno.h>
@ -17,22 +18,7 @@ static size_t __find_auxv(unsigned long type)
return (size_t) -1;
}
/// __auxv_init should happen BEFORE the first use of getauxval.
/// but getauxval can be used in other init sections (namely in musl/clock_gettime.c::cgt_init),
/// so constructor(0) is needed to prioritize that constructor
/// see also: https://stackoverflow.com/questions/11106875/attribute-constructor-call-order-confusion/11198936
__attribute__((constructor(0))) static void __auxv_init()
{
size_t i;
for (i = 0; __environ[i]; i++);
__auxv = (unsigned long *) (__environ + i + 1);
size_t secure_idx = __find_auxv(AT_SECURE);
if (secure_idx != ((size_t) -1))
__auxv_secure = __auxv[secure_idx];
}
unsigned long getauxval(unsigned long type)
unsigned long __getauxval(unsigned long type)
{
if (type == AT_SECURE)
return __auxv_secure;
@ -47,3 +33,29 @@ unsigned long getauxval(unsigned long type)
errno = ENOENT;
return 0;
}
static void * volatile getauxval_func;
static unsigned long __auxv_init(unsigned long type)
{
if (!__environ)
return 0;
size_t i;
for (i = 0; __environ[i]; i++);
__auxv = (unsigned long *) (__environ + i + 1);
size_t secure_idx = __find_auxv(AT_SECURE);
if (secure_idx != ((size_t) -1))
__auxv_secure = __auxv[secure_idx];
a_cas_p(&getauxval_func, (void *)__auxv_init, (void *)__getauxval);
return __getauxval(type);
}
static void * volatile getauxval_func = (void *)__auxv_init;
unsigned long getauxval(unsigned long type)
{
return ((unsigned long (*)(unsigned long))getauxval_func)(type);
}