395 lines
10 KiB
Diff
395 lines
10 KiB
Diff
diff --git a/ChangeLog b/ChangeLog
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index b42a4d7..baba19e 100644
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--- a/ChangeLog
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+++ b/ChangeLog
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@@ -1,3 +1,10 @@
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+ * Make it possible to use --enable-timeout-stat as well as
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+ --enable-timeout-stat=static for a static background process which
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+ does the final stat system calls
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+ * Do not mix HAVE_TIMEOUT_STAT with WITH_TIMEOUT_STAT
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+ * Add timeout.c/timeout.h for static background process which is able
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+ to read the file name from pipe, does the stat(2) system call, and
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+ writes the result back to a pipe.
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* Really add ASCII null at command string in add_proc() of pstree.c
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Changes in 22.16
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diff --git a/configure.ac b/configure.ac
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index 0615f5f..9265d82 100644
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--- a/configure.ac
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+++ b/configure.ac
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@@ -30,12 +30,16 @@ AC_SUBST([SELINUX_LIB])
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# Call fork before all stat calls to stop hanging on NFS mounts
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AC_SUBST([WITH_TIMEOUT_STAT])
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AC_ARG_ENABLE([timeout_stat],
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- [AS_HELP_STRING([--enable-timeout-stat], [Use a timeout on stat calls])],
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+ [AS_HELP_STRING([--enable-timeout-stat], [Use a timeout on stat calls (optional with argument "static" for a static background process)])],
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[enable_timeout_stat=$enableval],
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[enable_timeout_stat="no"])
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if test "$enable_timeout_stat" = "yes"; then
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AC_DEFINE([WITH_TIMEOUT_STAT], [1], [Use timeout on stat calls])
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fi
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+if test "$enable_timeout_stat" = "static"; then
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+ AC_DEFINE([WITH_TIMEOUT_STAT], [2], [Use timeout on stat calls])
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+fi
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+AM_CONDITIONAL([WANT_TIMEOUT_STAT], [test "$enable_timeout_stat" = "static"])
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# Enable hardened compile and link flags
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AC_ARG_ENABLE([harden_flags],
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diff --git a/src/Makefile.am b/src/Makefile.am
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index d511f24..a28af7d 100644
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--- a/src/Makefile.am
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+++ b/src/Makefile.am
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@@ -24,6 +24,9 @@ if WANT_PEEKFD_MIPS
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endif
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fuser_SOURCES = fuser.c comm.h signals.c signals.h i18n.h fuser.h lists.h
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+if WANT_TIMEOUT_STAT
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+ fuser_SOURCES += timeout.c timeout.h
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+endif
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fuser_LDADD = @LIBINTL@
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diff --git a/src/fuser.c b/src/fuser.c
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index e4081eb..09548ff 100644
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--- a/src/fuser.c
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+++ b/src/fuser.c
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@@ -111,9 +111,13 @@ static dev_t device(const char *path);
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#endif
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static char *expandpath(const char *path);
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-typedef int (*stat_t)(const char*, struct stat*);
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#ifdef WITH_TIMEOUT_STAT
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+# if (WITH_TIMEOUT_STAT == 2)
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+# include "timeout.h"
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+# else
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+typedef int (*stat_t)(const char*, struct stat*);
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static int timeout(stat_t func, const char *path, struct stat *buf, unsigned int seconds);
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+# endif
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#else
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#define timeout(func,path,buf,dummy) (func)((path),(buf))
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#endif /* WITH_TIMEOUT_STAT */
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@@ -1783,7 +1787,7 @@ scan_swaps(struct names *names_head, struct inode_list *ino_head,
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* Execute stat(2) system call with timeout to avoid deadlock
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* on network based file systems.
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*/
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-#ifdef HAVE_TIMEOUT_STAT
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+#if defined(WITH_TIMEOUT_STAT) && (WITH_TIMEOUT_STAT == 1)
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static sigjmp_buf jenv;
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diff --git a/src/timeout.c b/src/timeout.c
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new file mode 100644
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index 0000000..1fe0354
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--- /dev/null
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+++ b/src/timeout.c
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@@ -0,0 +1,267 @@
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+/*
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+ * timout.c Advanced timeout handling for file system calls
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+ * to avoid deadlocks on remote file shares.
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+ *
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+ * Version: 0.1 07-Sep-2011 Fink
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+ *
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+ * Copyright 2011 Werner Fink, 2011 SUSE LINUX Products GmbH, Germany.
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License as published by
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+ * the Free Software Foundation; either version 2 of the License, or
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+ * (at your option) any later version.
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+ *
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+ * Author: Werner Fink <werner@suse.de>, 2011
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+ */
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+
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+#ifndef _GNU_SOURCE
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+# define _GNU_SOURCE
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+#endif
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+
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+#ifndef USE_SOCKETPAIR
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+# define USE_SOCKETPAIR 1
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+#endif
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+
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+#ifdef _FEATURES_H
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+# error Include local config.h before any system header file
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+#endif
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+#include "config.h" /* For _FILE_OFFSET_BITS */
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+
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+#include <errno.h>
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+#include <pthread.h>
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+#include <setjmp.h>
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+#include <signal.h>
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+#include <stdlib.h>
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+#include <string.h>
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+#include <sys/time.h>
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+#include <sys/types.h>
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+#include <sys/select.h>
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+#include <sys/stat.h>
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+
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+#include <unistd.h>
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+#if USE_SOCKETPAIR
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+# include <sys/socket.h>
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+# include <netdb.h>
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+# include <netinet/in.h>
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+# ifndef SHUT_RD
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+# define SHUT_RD 0
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+# endif
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+# ifndef SHUT_WR
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+# define SHUT_WR 1
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+# endif
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+# undef pipe
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+# define pipe(v) (((socketpair(AF_UNIX,SOCK_STREAM,0,v) < 0) || \
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+ (shutdown((v)[1],SHUT_RD) < 0) || (shutdown((v)[0],SHUT_WR) < 0)) ? -1 : 0)
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+#endif
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+#include <wait.h>
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+
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+#include "timeout.h"
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+
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+#if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L)
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+# ifndef destructor
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+# define destructor __destructor__
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+# endif
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+# ifndef constructor
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+# define constructor __constructor__
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+# endif
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+# ifndef packed
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+# define packed __packed__
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+# endif
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+# ifndef inline
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+# define inline __inline__
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+# endif
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+# ifndef unused
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+# define unused __unused__
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+# endif
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+# ifndef volatile
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+# define volatile __volatile__
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+# endif
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+#endif
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+#ifndef attribute
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+# define attribute(attr) __attribute__(attr)
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+#endif
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+
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+#if defined __GNUC__
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+# undef strcpy
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+# define strcpy(d,s) __builtin_strcpy((d),(s)) /* Without boundary check please */
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+#endif
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+
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+/*
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+ * The structure used for communication between the processes
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+ */
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+typedef struct _handle {
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+ int errcode;
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+ struct stat argument;
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+ stat_t function;
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+ size_t len;
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+ char path[0];
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+} attribute((packed)) handle_t;
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+
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+/*
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+ * Using a forked process for doing e.g. stat(2) system call as this
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+ * allows us to send e.g. SIGKILL to this process if it hangs in `D'
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+ * state on a file share due a stalled NFS server. This does not work
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+ * with (p)threads as SIGKILL would kill all threads including main.
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+ */
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+
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+static volatile pid_t active;
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+static int pipes[4] = {-1, -1, -1, -1};
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+static char buf[PATH_MAX + sizeof(handle_t) + 1];
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+
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+static void sigchild(int sig attribute((unused)))
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+{
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+ pid_t pid = waitpid(active, NULL, WNOHANG|WUNTRACED);
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+ if (pid <= 0)
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+ return;
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+ if (errno == ECHILD)
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+ return;
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+ active = 0;
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+}
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+
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+static void attribute((constructor)) start(void)
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+{
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+ sigset_t sigset, oldset;
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+ struct sigaction act;
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+ ssize_t in;
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+
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+ if (pipes[1] >= 0) close(pipes[1]);
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+ if (pipes[2] >= 0) close(pipes[2]);
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+
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+ if (pipe(&pipes[0]))
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+ goto error;
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+ if (pipe(&pipes[2]))
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+ goto error;
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+
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+ memset(&act, 0, sizeof(act));
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+ sigemptyset(&act.sa_mask);
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+ act.sa_flags = SA_RESTART;
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+ act.sa_handler = sigchild;
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+ sigaction(SIGCHLD, &act, 0);
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+
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+ if ((active = fork()) < 0)
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+ goto error;
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+
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+ if (active) {
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+ close(pipes[0]);
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+ close(pipes[3]);
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+ pipes[0] = pipes[3] = -1;
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+ return;
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+ }
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+
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+ sigemptyset(&sigset);
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+ sigaddset(&sigset, SIGALRM);
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+ sigprocmask(SIG_BLOCK, &sigset, &oldset);
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+
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+ act.sa_handler = SIG_DFL;
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+ sigaction(SIGCHLD, &act, 0);
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+
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+ close(pipes[1]);
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+ close(pipes[2]);
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+ dup2(pipes[0], STDIN_FILENO);
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+ dup2(pipes[3], STDOUT_FILENO);
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+ close(pipes[0]);
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+ close(pipes[3]);
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+ pipes[1] = pipes[2] = -1;
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+ pipes[0] = pipes[3] = -1;
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+
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+ {
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+ handle_t *restrict handle = (void*)&buf[0];
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+
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+ while ((in = read(STDIN_FILENO, handle, sizeof(buf))) > sizeof(handle_t)) {
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+ if (handle->function(handle->path, &handle->argument) < 0)
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+ handle->errcode = errno;
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+ write(STDOUT_FILENO, &handle->errcode, sizeof(handle->errcode)+sizeof(handle->argument));
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+ memset(handle, 0, sizeof(handle_t));
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+ }
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+ }
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+ sigprocmask(SIG_SETMASK, &oldset, NULL);
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+ exit(0);
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+error:
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+ if (pipes[0] >= 0) close(pipes[0]);
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+ if (pipes[1] >= 0) close(pipes[1]);
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+ if (pipes[2] >= 0) close(pipes[2]);
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+ if (pipes[3] >= 0) close(pipes[3]);
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+}
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+
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+static void /* attribute((destructor)) */ stop(void)
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+{
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+ if (active && waitpid(active, NULL, WNOHANG|WUNTRACED) == 0)
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+ kill(active, SIGKILL);
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+}
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+
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+static sigjmp_buf jenv;
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+static void sigjump(int sig attribute((unused)))
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+{
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+ siglongjmp(jenv, 1);
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+}
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+
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+/*
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+ * External routine
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+ */
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+int timeout(stat_t function, const char *path, struct stat *restrict argument, time_t seconds)
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+{
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+ handle_t *restrict handle = (void*)&buf[0];
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+ struct sigaction alrm_act, pipe_act, new_act;
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+ sigset_t sigset, oldset;
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+
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+ if (active <= 0) /* Oops, last one failed therefore clear status and restart */
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+ start();
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+
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+ memset(handle, 0, sizeof(handle_t));
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+ handle->len = strlen(path) + 1;
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+ if (handle->len >= PATH_MAX) {
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+ errno = ENAMETOOLONG;
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+ goto error;
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+ }
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+ handle->errcode = 0;
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+ handle->argument = *argument;
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+ handle->function = function;
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+ strcpy(handle->path, path);
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+
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+ sigemptyset(&sigset);
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+ sigaddset(&sigset, SIGALRM);
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+ sigaddset(&sigset, SIGPIPE);
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+ sigprocmask(SIG_UNBLOCK, &sigset, &oldset);
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+
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+ memset(&new_act, 0, sizeof(new_act));
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+ sigemptyset(&new_act.sa_mask);
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+ new_act.sa_flags = SA_RESETHAND;
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+
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+ if (sigsetjmp(jenv, 1))
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+ goto timed;
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+
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+ new_act.sa_handler = sigjump;
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+ sigaction(SIGALRM, &new_act, &alrm_act);
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+ sigaction(SIGPIPE, &new_act, &pipe_act);
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+ alarm(seconds);
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+
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+ write(pipes[1], handle, sizeof(handle_t)+handle->len);
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+ read(pipes[2], &handle->errcode, sizeof(handle->errcode)+sizeof(handle->argument));
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+
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+ alarm(0);
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+ sigaction(SIGPIPE, &pipe_act, NULL);
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+ sigaction(SIGALRM, &alrm_act, NULL);
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+
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+ if (handle->errcode) {
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+ errno = handle->errcode;
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+ goto error;
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+ }
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+
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+ *argument = handle->argument;
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+ sigprocmask(SIG_SETMASK, &oldset, NULL);
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+
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+ return 0;
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+timed:
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+ (void) alarm(0);
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+ sigaction(SIGPIPE, &pipe_act, NULL);
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+ sigaction(SIGALRM, &alrm_act, NULL);
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+ sigprocmask(SIG_SETMASK, &oldset, NULL);
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+ stop();
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+ errno = ETIMEDOUT;
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+error:
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+ return -1;
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+}
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+
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+/*
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+ * End of timeout.c
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+ */
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diff --git a/src/timeout.h b/src/timeout.h
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new file mode 100644
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index 0000000..546c13b
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--- /dev/null
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+++ b/src/timeout.h
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@@ -0,0 +1,36 @@
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+/*
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+ * timout.h Advanced timeout handling for file system calls
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+ * to avoid deadlocks on remote file shares.
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+ *
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+ * Version: 0.1 07-Sep-2011 Fink
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+ *
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+ * Copyright 2011 Werner Fink, 2011 SUSE LINUX Products GmbH, Germany.
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License as published by
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+ * the Free Software Foundation; either version 2 of the License, or
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+ * (at your option) any later version.
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+ *
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+ * Author: Werner Fink <werner@suse.de>, 2011
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+ */
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+
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+#ifndef _TIMEOUT_H
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+#define _TIMEOUT_H
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+
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+#include "config.h" /* For _FILE_OFFSET_BITS */
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+
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+#include <sys/types.h>
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+#include <sys/stat.h>
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+#include <time.h>
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+#include <limits.h>
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+
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+#if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L)
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+# ifndef restrict
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+# define restrict __restrict__
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+# endif
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+#endif
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+
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+typedef int (*stat_t)(const char *, struct stat *restrict);
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+extern int timeout(stat_t, const char *, struct stat *restrict, time_t);
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+
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+#endif
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