235 lines
7.0 KiB
Diff
235 lines
7.0 KiB
Diff
commit ad615b59c78d6d37fee921fb2b2ae6b72c930625
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Tue Sep 28 18:55:49 2021 +0200
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Linux: Simplify __opensock and fix race condition [BZ #28353]
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AF_NETLINK support is not quite optional on modern Linux systems
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anymore, so it is likely that the first attempt will always succeed.
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Consequently, there is no need to cache the result. Keep AF_UNIX
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and the Internet address families as a fallback, for the rare case
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that AF_NETLINK is missing. The other address families previously
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probed are totally obsolete be now, so remove them.
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Use this simplified version as the generic implementation, disabling
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Netlink support as needed.
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(cherry picked from commit 5bf07e1b3a74232bfb8332275110be1a5da50f83)
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diff --git a/socket/opensock.c b/socket/opensock.c
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index 37148d4743343ff4..ff94d27a61bd3889 100644
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--- a/socket/opensock.c
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+++ b/socket/opensock.c
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@@ -1,4 +1,5 @@
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-/* Copyright (C) 1999-2021 Free Software Foundation, Inc.
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+/* Create socket with an unspecified address family for use with ioctl.
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+ Copyright (C) 1999-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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@@ -15,56 +16,34 @@
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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-#include <stdio.h>
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+#include <errno.h>
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#include <sys/socket.h>
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-#include <libc-lock.h>
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/* Return a socket of any type. The socket can be used in subsequent
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ioctl calls to talk to the kernel. */
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int
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__opensock (void)
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{
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- /* Cache the last AF that worked, to avoid many redundant calls to
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- socket(). */
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- static int sock_af = -1;
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- int fd = -1;
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- __libc_lock_define_initialized (static, lock);
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-
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- if (sock_af != -1)
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- {
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- fd = __socket (sock_af, SOCK_DGRAM, 0);
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- if (fd != -1)
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- return fd;
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- }
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-
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- __libc_lock_lock (lock);
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-
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- if (sock_af != -1)
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- fd = __socket (sock_af, SOCK_DGRAM, 0);
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-
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- if (fd == -1)
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- {
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-#ifdef AF_INET
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- fd = __socket (sock_af = AF_INET, SOCK_DGRAM, 0);
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-#endif
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-#ifdef AF_INET6
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- if (fd < 0)
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- fd = __socket (sock_af = AF_INET6, SOCK_DGRAM, 0);
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-#endif
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-#ifdef AF_IPX
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- if (fd < 0)
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- fd = __socket (sock_af = AF_IPX, SOCK_DGRAM, 0);
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-#endif
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-#ifdef AF_AX25
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- if (fd < 0)
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- fd = __socket (sock_af = AF_AX25, SOCK_DGRAM, 0);
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-#endif
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-#ifdef AF_APPLETALK
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- if (fd < 0)
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- fd = __socket (sock_af = AF_APPLETALK, SOCK_DGRAM, 0);
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+ /* SOCK_DGRAM is supported by all address families. (Netlink does
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+ not support SOCK_STREAM.) */
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+ int type = SOCK_DGRAM | SOCK_CLOEXEC;
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+ int fd;
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+
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+#ifdef AF_NETLINK
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+ fd = __socket (AF_NETLINK, type, 0);
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+ if (fd >= 0)
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+ return fd;
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#endif
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- }
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- __libc_lock_unlock (lock);
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+ fd = __socket (AF_UNIX, type, 0);
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+ if (fd >= 0)
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+ return fd;
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+ fd = __socket (AF_INET, type, 0);
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+ if (fd >= 0)
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+ return fd;
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+ fd = __socket (AF_INET6, type, 0);
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+ if (fd >= 0)
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+ return fd;
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+ __set_errno (ENOENT);
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return fd;
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}
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diff --git a/sysdeps/unix/sysv/linux/opensock.c b/sysdeps/unix/sysv/linux/opensock.c
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deleted file mode 100644
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index e87d6e58b0b84f82..0000000000000000
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--- a/sysdeps/unix/sysv/linux/opensock.c
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+++ /dev/null
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@@ -1,114 +0,0 @@
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-/* Copyright (C) 1999-2021 Free Software Foundation, Inc.
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- This file is part of the GNU C Library.
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-
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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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-
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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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-
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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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- <https://www.gnu.org/licenses/>. */
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-
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-#include <assert.h>
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-#include <errno.h>
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-#include <stdio.h>
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-#include <string.h>
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-#include <unistd.h>
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-#include <sys/socket.h>
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-
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-/* Return a socket of any type. The socket can be used in subsequent
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- ioctl calls to talk to the kernel. */
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-int
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-__opensock (void)
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-{
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- static int last_family; /* Available socket family we will use. */
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- static int last_type;
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- static const struct
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- {
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- int family;
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- const char procname[15];
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- } afs[] =
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- {
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- { AF_UNIX, "net/unix" },
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- { AF_INET, "" },
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- { AF_INET6, "net/if_inet6" },
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- { AF_AX25, "net/ax25" },
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- { AF_NETROM, "net/nr" },
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- { AF_ROSE, "net/rose" },
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- { AF_IPX, "net/ipx" },
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- { AF_APPLETALK, "net/appletalk" },
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- { AF_ECONET, "sys/net/econet" },
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- { AF_ASH, "sys/net/ash" },
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- { AF_X25, "net/x25" },
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-#ifdef NEED_AF_IUCV
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- { AF_IUCV, "net/iucv" }
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-#endif
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- };
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-#define nafs (sizeof (afs) / sizeof (afs[0]))
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- char fname[sizeof "/proc/" + 14];
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- int result;
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- int has_proc;
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- size_t cnt;
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-
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- /* We already know which family to use from the last call. Use it
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- again. */
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- if (last_family != 0)
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- {
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- assert (last_type != 0);
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-
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- result = __socket (last_family, last_type | SOCK_CLOEXEC, 0);
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- if (result != -1 || errno != EAFNOSUPPORT)
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- /* Maybe the socket type isn't supported anymore (module is
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- unloaded). In this case again try to find the type. */
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- return result;
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-
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- /* Reset the values. They seem not valid anymore. */
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- last_family = 0;
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- last_type = 0;
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- }
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-
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- /* Check whether the /proc filesystem is available. */
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- has_proc = __access ("/proc/net", R_OK) != -1;
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- strcpy (fname, "/proc/");
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-
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- /* Iterate over the interface families and find one which is
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- available. */
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- for (cnt = 0; cnt < nafs; ++cnt)
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- {
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- int type = SOCK_DGRAM;
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-
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- if (has_proc && afs[cnt].procname[0] != '\0')
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- {
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- strcpy (fname + 6, afs[cnt].procname);
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- if (__access (fname, R_OK) == -1)
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- /* The /proc entry is not available. I.e., we cannot
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- create a socket of this type (without loading the
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- module). Don't look for it since this might trigger
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- loading the module. */
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- continue;
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- }
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-
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- if (afs[cnt].family == AF_NETROM || afs[cnt].family == AF_X25)
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- type = SOCK_SEQPACKET;
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-
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- result = __socket (afs[cnt].family, type | SOCK_CLOEXEC, 0);
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- if (result != -1)
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- {
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- /* Found an available family. */
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- last_type = type;
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- last_family = afs[cnt].family;
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- return result;
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- }
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- }
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-
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- /* None of the protocol families is available. It is unclear what kind
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- of error is returned. ENOENT seems like a reasonable choice. */
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- __set_errno (ENOENT);
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- return -1;
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-}
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diff --git a/sysdeps/unix/sysv/linux/s390/opensock.c b/sysdeps/unix/sysv/linux/s390/opensock.c
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deleted file mode 100644
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index f099d651ff04d211..0000000000000000
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--- a/sysdeps/unix/sysv/linux/s390/opensock.c
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+++ /dev/null
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@@ -1,2 +0,0 @@
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-#define NEED_AF_IUCV 1
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-#include "../opensock.c"
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