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6f9d4f595e
_res_hconf.initialized was not suitable for use in a multi-threaded environment due to the lack of atomics and memory barriers. Use of it was also unnecessary because _res_hconf_init did the right thing by using __libc_once. This patch fixes the glibc-internal uses by just calling _res_hconf_init unconditionally, and switches to a release MO atomic store for _res_hconf.initialized to fix the glibc side of the synchronization problem (which will maintain backward compatibility, but cannot fix the lack of acquire MO on any glibc-external loads). [BZ #20477] * resolv/res_hconf.c (do_init): Use atomic access. * resolv/res_hconf.h: Add comments. * nscd/aicache.c (addhstaiX): Call _res_hconf_init unconditionally. * nss/getXXbyYY_r.c (REENTRANT_NAME): Likewise. * sysdeps/posix/getaddrinfo.c (gaih_inet): Likewise.
57 lines
2.3 KiB
C
57 lines
2.3 KiB
C
/* Copyright (C) 1993-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by David Mosberger (davidm@azstarnet.com).
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _RES_HCONF_H_
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#define _RES_HCONF_H_
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#include <netdb.h>
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#define TRIMDOMAINS_MAX 4
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struct hconf
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{
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/* We keep the INITIALIZED member only for backwards compatibility. New
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code should just call _res_hconf_init unconditionally. For this field
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to be used safely, users must ensure that either (1) a call to
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_res_hconf_init happens-before any load from INITIALIZED, or (2) an
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assignment of zero to INITIALIZED happens-before any load from it, and
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these loads use acquire MO if the intent is to skip calling
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_res_hconf_init if the load returns a nonzero value. Such acquire MO
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loads will then synchronize with the release MO store to INITIALIZED
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in do_init in res_hconf.c; see pthread_once for more detail. */
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int initialized;
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int unused1;
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int unused2[4];
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int num_trimdomains;
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const char *trimdomain[TRIMDOMAINS_MAX];
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unsigned int flags;
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# define HCONF_FLAG_INITED (1 << 0) /* initialized? */
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# define HCONF_FLAG_SPOOF (1 << 1) /* refuse spoofed addresses */
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# define HCONF_FLAG_SPOOFALERT (1 << 2) /* syslog warning of spoofed */
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# define HCONF_FLAG_REORDER (1 << 3) /* list best address first */
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# define HCONF_FLAG_MULTI (1 << 4) /* see comments for gethtbyname() */
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};
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extern struct hconf _res_hconf;
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extern void _res_hconf_init (void);
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extern void _res_hconf_trim_domain (char *domain);
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extern void _res_hconf_trim_domains (struct hostent *hp);
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extern void _res_hconf_reorder_addrs (struct hostent *hp);
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#endif /* _RES_HCONF_H_ */
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