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/*
* Copyright (c) 1995-1999 by Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/
#include <atomic.h>
#include <limits.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <bits/libc-lock.h>
#include <sys/stat.h>
/* The following bit is copied from res_data.c (where it is #ifdef'ed
out) since res_init() should go into libc.so but the rest of that
file should not. */
__libc_lock_define_initialized (static, lock);
extern unsigned long long int __res_initstamp attribute_hidden;
/* We have atomic increment operations on 64-bit platforms. */
#if __WORDSIZE == 64
# define atomicinclock(lock) (void) 0
# define atomicincunlock(lock) (void) 0
# define atomicinc(var) catomic_increment (&(var))
#else
# define atomicinclock(lock) __libc_lock_lock (lock)
# define atomicincunlock(lock) __libc_lock_unlock (lock)
# define atomicinc(var) ++var
#endif
int
res_init(void) {
extern int __res_vinit(res_state, int);
/*
* These three fields used to be statically initialized. This made
* it hard to use this code in a shared library. It is necessary,
* now that we're doing dynamic initialization here, that we preserve
* the old semantics: if an application modifies one of these three
* fields of _res before res_init() is called, res_init() will not
* alter them. Of course, if an application is setting them to
* _zero_ before calling res_init(), hoping to override what used
* to be the static default, we can't detect it and unexpected results
* will follow. Zero for any of these fields would make no sense,
* so one can safely assume that the applications were already getting
* unexpected results.
*
* _res.options is tricky since some apps were known to diddle the bits
* before res_init() was first called. We can't replicate that semantic
* with dynamic initialization (they may have turned bits off that are
* set in RES_DEFAULT). Our solution is to declare such applications
* "broken". They could fool us by setting RES_INIT but none do (yet).
*/
if (!_res.retrans)
_res.retrans = RES_TIMEOUT;
if (!_res.retry)
_res.retry = 4;
if (!(_res.options & RES_INIT))
_res.options = RES_DEFAULT;
else if (_res.nscount > 0)
__res_iclose (&_res, true); /* Close any VC sockets. */
/*
* This one used to initialize implicitly to zero, so unless the app
* has set it to something in particular, we can randomize it now.
*/
if (!_res.id)
_res.id = res_randomid();
atomicinclock (lock);
/* Request all threads to re-initialize their resolver states,
resolv.conf might have changed. */
atomicinc (__res_initstamp);
atomicincunlock (lock);
return (__res_vinit(&_res, 1));
}
/* Initialize resp if RES_INIT is not yet set or if res_init in some other
thread requested re-initializing. */
int
__res_maybe_init (res_state resp, int preinit)
{
static time_t last_mtime;
struct stat statbuf;
int ret;
if (resp->options & RES_INIT) {
ret = stat (_PATH_RESCONF, &statbuf);
__libc_lock_lock (lock);
if ((ret == 0) && (last_mtime != statbuf.st_mtime)) {
last_mtime = statbuf.st_mtime;
atomicinc (__res_initstamp);
}
__libc_lock_unlock (lock);
if (__res_initstamp != resp->_u._ext.initstamp) {
if (resp->nscount > 0)
__res_iclose (resp, true);
return __res_vinit (resp, 1);
}
return 0;
} else if (preinit) {
if (!resp->retrans)
resp->retrans = RES_TIMEOUT;
if (!resp->retry)
resp->retry = 4;
resp->options = RES_DEFAULT;
if (!resp->id)
resp->id = res_randomid ();
return __res_vinit (resp, 1);
} else
return __res_ninit (resp);
}
libc_hidden_def (__res_maybe_init)
/* This needs to be after the use of _res in res_init, above. */
#undef _res
/* The resolver state for use by single-threaded programs.
This differs from plain `struct __res_state _res;' in that it doesn't
create a common definition, but a plain symbol that resides in .bss,
which can have an alias. */
struct __res_state _res __attribute__ ((nocommon));
#undef __resp
__thread struct __res_state *__resp = &_res;
extern __thread struct __res_state *__libc_resp
__attribute__ ((alias ("__resp"))) attribute_hidden;
/* We declare this with compat_symbol so that it's not
visible at link time. Programs must use the accessor functions. */
#ifdef SHARED
# include <shlib-compat.h>
compat_symbol (libc, _res, _res, GLIBC_2_0);
#endif
#include <shlib-compat.h>
#if SHLIB_COMPAT(libc, GLIBC_2_0, GLIBC_2_2)
# undef res_init
extern int __res_init_weak (void);
weak_extern (__res_init_weak);
strong_alias (__res_init, __res_init_weak);
compat_symbol (libc, __res_init_weak, res_init, GLIBC_2_0);
#endif
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