+++ /dev/null
-/*
- * timout.c Advanced timeout handling for file system calls
- * to avoid deadlocks on remote file shares.
- *
- * Version: 0.2 11-Dec-2012 Fink
- *
- * Copyright 2011,2012 Werner Fink, 2011,2012 SUSE LINUX Products GmbH, Germany.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * Author: Werner Fink <werner@suse.de>, 2011
- */
-
-#ifndef _GNU_SOURCE
-# define _GNU_SOURCE
-#endif
-
-#ifdef _FEATURES_H
-# error Include local config.h before any system header file
-#endif
-#include "config.h"
-
-#ifndef WITH_TIMEOUT_STAT
-# define WITH_TIMEOUT_STAT 0
-#endif
-
-#ifndef USE_SOCKETPAIR
-# define USE_SOCKETPAIR 1
-#endif
-
-#include <errno.h>
-#include <setjmp.h>
-#include <signal.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/mman.h>
-#include <sys/time.h>
-#include <sys/types.h>
-#include <sys/select.h>
-#include <sys/stat.h>
-#include <unistd.h>
-#if USE_SOCKETPAIR
-# include <sys/socket.h>
-# include <netdb.h>
-# include <netinet/in.h>
-# ifndef SHUT_RD
-# define SHUT_RD 0
-# endif
-# ifndef SHUT_WR
-# define SHUT_WR 1
-# endif
-# undef pipe
-# define pipe(v) (((socketpair(AF_UNIX,SOCK_STREAM,0,v) < 0) || \
- (shutdown((v)[1],SHUT_RD) < 0) || (shutdown((v)[0],SHUT_WR) < 0)) ? -1 : 0)
-#endif
-#include <wait.h>
-
-#include "timeout.h"
-
-#if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L)
-# ifndef destructor
-# define destructor __destructor__
-# endif
-# ifndef constructor
-# define constructor __constructor__
-# endif
-# ifndef packed
-# define packed __packed__
-# endif
-# ifndef inline
-# define inline __inline__
-# endif
-# ifndef unused
-# define unused __unused__
-# endif
-# ifndef volatile
-# define volatile __volatile__
-# endif
-#endif
-#ifndef attribute
-# define attribute(attr) __attribute__(attr)
-#endif
-
-#if defined __GNUC__
-# undef strcpy
-# define strcpy(d,s) __builtin_strcpy((d),(s)) /* Without boundary check please */
-#endif
-
-#if WITH_TIMEOUT_STAT
-static sigjmp_buf jenv;
-static void sigjump(int sig attribute((unused)))
-{
- siglongjmp(jenv, 1);
-}
-#endif
-
-#if WITH_TIMEOUT_STAT == 2
-/*
- * The structure used for communication between the processes
- */
-typedef struct _handle {
- int errcode;
- struct stat argument;
- stat_t function;
- size_t len;
- char path[0];
-} attribute((packed)) handle_t;
-
-/*
- * Using a forked process for doing e.g. stat(2) system call as this
- * allows us to send e.g. SIGKILL to this process if it hangs in `D'
- * state on a file share due a stalled NFS server. This does not work
- * with (p)threads as SIGKILL would kill all threads including main.
- */
-
-static volatile pid_t active;
-static int pipes[4] = {-1, -1, -1, -1};
-static handle_t *restrict handle;
-static const size_t buflen = PATH_MAX+sizeof(handle_t)+1;
-
-static void sigchild(int sig attribute((unused)))
-{
- pid_t pid = waitpid(active, NULL, WNOHANG|WUNTRACED);
- if (pid <= 0)
- return;
- if (errno == ECHILD)
- return;
- active = 0;
-}
-
-static void attribute((constructor)) start(void)
-{
- sigset_t sigset, oldset;
- struct sigaction act;
- char sync[1];
- ssize_t in;
-
- if (pipes[1] >= 0) close(pipes[1]);
- if (pipes[2] >= 0) close(pipes[2]);
-
- if (pipe(&pipes[0]))
- goto error;
- if (pipe(&pipes[2]))
- goto error;
-
- memset(&act, 0, sizeof(act));
- sigemptyset(&act.sa_mask);
- act.sa_flags = SA_RESTART;
- act.sa_handler = sigchild;
- sigaction(SIGCHLD, &act, 0);
-
- if (!handle)
- handle = mmap(NULL, buflen, PROT_READ|PROT_WRITE,
- MAP_ANONYMOUS|MAP_SHARED, -1, 0);
- if (handle == MAP_FAILED)
- goto error;
-
- if ((active = fork()) < 0)
- goto error;
-
- if (active) {
- close(pipes[0]);
- close(pipes[3]);
- pipes[0] = pipes[3] = -1;
- return;
- }
-
- sigemptyset(&sigset);
- sigaddset(&sigset, SIGALRM);
- sigprocmask(SIG_BLOCK, &sigset, &oldset);
-
- act.sa_handler = SIG_DFL;
- sigaction(SIGCHLD, &act, 0);
-
- close(pipes[1]);
- close(pipes[2]);
- dup2(pipes[0], STDIN_FILENO);
- dup2(pipes[3], STDOUT_FILENO);
- close(pipes[0]);
- close(pipes[3]);
- pipes[1] = pipes[2] = -1;
- pipes[0] = pipes[3] = -1;
-
- while ((in = read(STDIN_FILENO, &sync, sizeof(sync))) != 0) {
- ssize_t out;
- if (in < 0) {
- if (errno == EINTR)
- continue;
- break;
- }
- if (!handle)
- break;
- if (handle->function(handle->path, &handle->argument) < 0)
- handle->errcode = errno;
- do
- out = write(STDOUT_FILENO, &sync, sizeof(sync));
- while (out < 0 && errno == EINTR);
- }
-
- sigprocmask(SIG_SETMASK, &oldset, NULL);
- exit(0);
-error:
- if (pipes[0] >= 0) close(pipes[0]);
- if (pipes[1] >= 0) close(pipes[1]);
- if (pipes[2] >= 0) close(pipes[2]);
- if (pipes[3] >= 0) close(pipes[3]);
- if (handle && handle != MAP_FAILED)
- munmap(handle, buflen);
- handle = NULL;
-}
-
-static void /* attribute((destructor)) */ stop(void)
-{
- if (active && waitpid(active, NULL, WNOHANG|WUNTRACED) == 0)
- kill(active, SIGKILL);
-}
-
-/*
- * External routine
- *
- * Execute stat(2) system call with timeout to avoid deadlock
- * on network based file systems.
- *
- */
-int
-timeout(stat_t function, const char *path, struct stat *restrict argument, time_t seconds)
-{
- struct sigaction alrm_act, pipe_act, new_act;
- sigset_t sigset, oldset;
- char sync[1] = "x";
-
- if (active <= 0) /* Oops, last one failed therefore clear status and restart */
- start();
- if (!handle) /* No shared memory area */
- return function(path, argument);
- memset(handle, 0, sizeof(handle_t));
- handle->len = strlen(path) + 1;
- if (handle->len >= PATH_MAX) {
- errno = ENAMETOOLONG;
- goto error;
- }
- handle->errcode = 0;
- handle->argument = *argument;
- handle->function = function;
- strcpy(handle->path, path);
-
- sigemptyset(&sigset);
- sigaddset(&sigset, SIGALRM);
- sigaddset(&sigset, SIGPIPE);
- sigprocmask(SIG_UNBLOCK, &sigset, &oldset);
-
- memset(&new_act, 0, sizeof(new_act));
- sigemptyset(&new_act.sa_mask);
- new_act.sa_flags = SA_RESETHAND;
-
- if (sigsetjmp(jenv, 1))
- goto timed;
-
- new_act.sa_handler = sigjump;
- sigaction(SIGALRM, &new_act, &alrm_act);
- sigaction(SIGPIPE, &new_act, &pipe_act);
- alarm(seconds);
-
- write(pipes[1], &sync, sizeof(sync));
- read(pipes[2], &sync, sizeof(sync));
-
- alarm(0);
- sigaction(SIGPIPE, &pipe_act, NULL);
- sigaction(SIGALRM, &alrm_act, NULL);
-
- if (handle->errcode) {
- errno = handle->errcode;
- goto error;
- }
-
- *argument = handle->argument;
- sigprocmask(SIG_SETMASK, &oldset, NULL);
-
- return 0;
-timed:
- (void) alarm(0);
- sigaction(SIGPIPE, &pipe_act, NULL);
- sigaction(SIGALRM, &alrm_act, NULL);
- sigprocmask(SIG_SETMASK, &oldset, NULL);
- stop();
- errno = ETIMEDOUT;
-error:
- return -1;
-}
-#elif WITH_TIMEOUT_STAT == 1
-/*
- * External routine
- *
- * Execute stat(2) system call with timeout to avoid deadlock
- * on network based file systems.
- *
- */
-int
-timeout(stat_t function, const char *path, struct stat *restrict argument, time_t seconds)
-{
- struct sigaction alrm_act, pipe_act, new_act;
- sigset_t sigset, oldset;
- int ret = 0, pipes[4];
- pid_t pid = 0;
- ssize_t len;
-
- if (pipe(&pipes[0]) < 0)
- goto error;
- switch ((pid = fork())) {
- case -1:
- close(pipes[0]);
- close(pipes[1]);
- goto error;
- case 0:
- new_act.sa_handler = SIG_DFL;
- sigaction(SIGALRM, &new_act, NULL);
- close(pipes[0]);
- if ((ret = function(path, argument)) == 0)
- do
- len = write(pipes[1], argument, sizeof(struct stat));
- while (len < 0 && errno == EINTR);
- close(pipes[1]);
- exit(ret);
- default:
- close(pipes[1]);
-
- sigemptyset(&sigset);
- sigaddset(&sigset, SIGALRM);
- sigaddset(&sigset, SIGPIPE);
- sigprocmask(SIG_UNBLOCK, &sigset, &oldset);
-
- memset(&new_act, 0, sizeof(new_act));
- sigemptyset(&new_act.sa_mask);
-
- if (sigsetjmp(jenv, 1))
- goto timed;
-
- new_act.sa_handler = sigjump;
- sigaction(SIGALRM, &new_act, &alrm_act);
- sigaction(SIGPIPE, &new_act, &pipe_act);
- alarm(seconds);
- if (read(pipes[0], argument, sizeof(struct stat)) == 0) {
- errno = EFAULT;
- ret = -1;
- }
- (void)alarm(0);
- sigaction(SIGPIPE, &pipe_act, NULL);
- sigaction(SIGALRM, &alrm_act, NULL);
-
- close(pipes[0]);
- waitpid(pid, NULL, 0);
- break;
- }
- return ret;
-timed:
- (void)alarm(0);
- sigaction(SIGPIPE, &pipe_act, NULL);
- sigaction(SIGALRM, &alrm_act, NULL);
- if (waitpid(0, NULL, WNOHANG) == 0)
- kill(pid, SIGKILL);
- errno = ETIMEDOUT;
-error:
- return -1;
-}
-#endif
-
-/*
- * End of timeout.c
- */
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