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Some aspects of the cgroups setup / detection code are quite subtle and easy to break. It would greatly benefit from unit testing, but this is difficult because the test suite won't have privileges to play around with cgroups. The solution is to use monkey patching via LD_PRELOAD to override the fopen, open, mkdir, access functions to redirect access of cgroups files to some magic stubs in the test suite. Using this we provide custom content for the /proc/cgroup and /proc/self/mounts files which report a fixed cgroup setup. We then override open/mkdir/access so that access to the cgroups filesystem gets redirected into files in a temporary directory tree in the test suite build dir. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
453 lines
15 KiB
C
453 lines
15 KiB
C
/*
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* Copyright (C) 2013 Red Hat, Inc.
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*
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* This 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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* This 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 this library. If not, see
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* <http://www.gnu.org/licenses/>.
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*
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* Author: Daniel P. Berrange <berrange@redhat.com>
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*/
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#include <config.h>
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#ifdef __linux__
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# include "internal.h"
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# include <stdio.h>
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# include <dlfcn.h>
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# include <stdlib.h>
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# include <unistd.h>
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# include <fcntl.h>
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# include <sys/stat.h>
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# include <stdarg.h>
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static int (*realopen)(const char *path, int flags, ...);
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static FILE *(*realfopen)(const char *path, const char *mode);
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static int (*realaccess)(const char *path, int mode);
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static int (*realmkdir)(const char *path, mode_t mode);
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static char *fakesysfsdir;
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# define SYSFS_PREFIX "/not/really/sys/fs/cgroup/"
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/*
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* The plan:
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*
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* We fake out /proc/mounts, so make it look as is cgroups
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* are mounted on /not/really/sys/fs/cgroup. We don't
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* use /sys/fs/cgroup, because we want to make it easy to
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* detect places where we've not mocked enough syscalls.
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*
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* In any open/acces/mkdir calls we look at path and if
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* it starts with /not/really/sys/fs/cgroup, we rewrite
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* the path to point at a temporary directory referred
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* to by LIBVIRT_FAKE_SYSFS_DIR env variable that is
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* set by the main test suite
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*
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* In mkdir() calls, we simulate the cgroups behaviour
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* whereby creating the directory auto-creates a bunch
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* of files beneath it
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*/
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/*
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* Intentionally missing the 'devices' mount.
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* Co-mounting cpu & cpuacct controllers
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* An anonymous controller for systemd
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*/
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const char *mounts =
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"rootfs / rootfs rw 0 0\n"
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"tmpfs /run tmpfs rw,seclabel,nosuid,nodev,mode=755 0 0\n"
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"tmpfs /not/really/sys/fs/cgroup tmpfs rw,seclabel,nosuid,nodev,noexec,mode=755 0 0\n"
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"cgroup /not/really/sys/fs/cgroup/systemd cgroup rw,nosuid,nodev,noexec,relatime,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd 0 0\n"
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"cgroup /not/really/sys/fs/cgroup/cpuset cgroup rw,nosuid,nodev,noexec,relatime,cpuset 0 0\n"
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"cgroup /not/really/sys/fs/cgroup/cpu,cpuacct cgroup rw,nosuid,nodev,noexec,relatime,cpuacct,cpu 0 0\n"
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"cgroup /not/really/sys/fs/cgroup/freezer cgroup rw,nosuid,nodev,noexec,relatime,freezer 0 0\n"
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"cgroup /not/really/sys/fs/cgroup/blkio cgroup rw,nosuid,nodev,noexec,relatime,blkio 0 0\n"
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"cgroup /not/really/sys/fs/cgroup/memory cgroup rw,nosuid,nodev,noexec,relatime,memory 0 0\n"
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"/dev/sda1 /boot ext4 rw,seclabel,relatime,data=ordered 0 0\n"
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"tmpfs /tmp tmpfs rw,seclabel,relatime,size=1024000k 0 0\n";
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const char *cgroups =
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"115:memory:/\n"
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"8:blkio:/\n"
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"6:freezer:/\n"
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"3:cpuacct,cpu:/system\n"
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"2:cpuset:/\n"
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"1:name=systemd:/user/berrange/123\n";
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static int make_file(const char *path,
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const char *name,
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const char *value)
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{
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int fd = -1;
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int ret = -1;
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char *filepath = NULL;
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if (asprintf(&filepath, "%s/%s", path, name) < 0)
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return -1;
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if ((fd = realopen(filepath, O_CREAT|O_WRONLY, 0600)) < 0)
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goto cleanup;
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if (write(fd, value, strlen(value)) != strlen(value))
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goto cleanup;
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ret = 0;
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cleanup:
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if (fd != -1 && close(fd) < 0)
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ret = -1;
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free(filepath);
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return ret;
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}
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static int make_controller(const char *path, mode_t mode)
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{
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int ret = -1;
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const char *controller;
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if (!STRPREFIX(path, fakesysfsdir)) {
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errno = EINVAL;
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return -1;
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}
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controller = path + strlen(fakesysfsdir) + 1;
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if (STREQ(controller, "cpu"))
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return symlink("cpu,cpuacct", path);
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if (STREQ(controller, "cpuacct"))
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return symlink("cpu,cpuacct", path);
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if (realmkdir(path, mode) < 0)
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goto cleanup;
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# define MAKE_FILE(name, value) \
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do { \
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if (make_file(path, name, value) < 0) \
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goto cleanup; \
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} while (0)
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if (STRPREFIX(controller, "cpu,cpuacct")) {
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MAKE_FILE("cpu.cfs_period_us", "100000\n");
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MAKE_FILE("cpu.cfs_quota_us", "-1\n");
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MAKE_FILE("cpu.rt_period_us", "1000000\n");
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MAKE_FILE("cpu.rt_runtime_us", "950000\n");
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MAKE_FILE("cpu.shares", "1024\n");
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MAKE_FILE("cpu.stat",
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"nr_periods 0\n"
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"nr_throttled 0\n"
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"throttled_time 0\n");
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MAKE_FILE("cpuacct.stat",
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"user 216687025\n"
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"system 43421396\n");
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MAKE_FILE("cpuacct.usage", "2787788855799582\n");
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MAKE_FILE("cpuacct.usage_per_cpu", "1413142688153030 1374646168910542\n");
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} else if (STRPREFIX(controller, "cpuset")) {
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MAKE_FILE("cpuset.cpu_exclusive", "1\n");
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if (STREQ(controller, "cpuset"))
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MAKE_FILE("cpuset.cpus", "0-1");
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else
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MAKE_FILE("cpuset.cpus", ""); /* Values don't inherit */
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MAKE_FILE("cpuset.mem_exclusive", "1\n");
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MAKE_FILE("cpuset.mem_hardwall", "0\n");
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MAKE_FILE("cpuset.memory_migrate", "0\n");
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MAKE_FILE("cpuset.memory_pressure", "0\n");
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MAKE_FILE("cpuset.memory_pressure_enabled", "0\n");
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MAKE_FILE("cpuset.memory_spread_page", "0\n");
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MAKE_FILE("cpuset.memory_spread_slab", "0\n");
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if (STREQ(controller, "cpuset"))
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MAKE_FILE("cpuset.mems", "0");
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else
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MAKE_FILE("cpuset.mems", ""); /* Values don't inherit */
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MAKE_FILE("cpuset.sched_load_balance", "1\n");
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MAKE_FILE("cpuset.sched_relax_domain_level", "-1\n");
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} else if (STRPREFIX(controller, "memory")) {
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MAKE_FILE("memory.failcnt", "0\n");
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MAKE_FILE("memory.force_empty", ""); /* Write only */
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MAKE_FILE("memory.kmem.tcp.failcnt", "0\n");
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MAKE_FILE("memory.kmem.tcp.limit_in_bytes", "9223372036854775807\n");
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MAKE_FILE("memory.kmem.tcp.max_usage_in_bytes", "0\n");
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MAKE_FILE("memory.kmem.tcp.usage_in_bytes", "16384\n");
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MAKE_FILE("memory.limit_in_bytes", "9223372036854775807\n");
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MAKE_FILE("memory.max_usage_in_bytes", "0\n");
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MAKE_FILE("memory.memsw.failcnt", ""); /* Not supported */
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MAKE_FILE("memory.memsw.limit_in_bytes", ""); /* Not supported */
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MAKE_FILE("memory.memsw.max_usage_in_bytes", ""); /* Not supported */
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MAKE_FILE("memory.memsw.usage_in_bytes", ""); /* Not supported */
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MAKE_FILE("memory.move_charge_at_immigrate", "0\n");
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MAKE_FILE("memory.numa_stat",
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"total=367664 N0=367664\n"
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"file=314764 N0=314764\n"
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"anon=51999 N0=51999\n"
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"unevictable=901 N0=901\n");
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MAKE_FILE("memory.oom_control",
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"oom_kill_disable 0\n"
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"under_oom 0\n");
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MAKE_FILE("memory.soft_limit_in_bytes", "9223372036854775807\n");
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MAKE_FILE("memory.stat",
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"cache 1336619008\n"
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"rss 97792000\n"
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"mapped_file 42090496\n"
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"pgpgin 13022605027\n"
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"pgpgout 13023820533\n"
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"pgfault 54429417056\n"
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"pgmajfault 315715\n"
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"inactive_anon 145887232\n"
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"active_anon 67100672\n"
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"inactive_file 627400704\n"
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"active_file 661872640\n"
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"unevictable 3690496\n"
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"hierarchical_memory_limit 9223372036854775807\n"
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"total_cache 1336635392\n"
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"total_rss 118689792\n"
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"total_mapped_file 42106880\n"
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"total_pgpgin 13022606816\n"
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"total_pgpgout 13023820793\n"
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"total_pgfault 54429422313\n"
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"total_pgmajfault 315715\n"
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"total_inactive_anon 145891328\n"
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"total_active_anon 88010752\n"
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"total_inactive_file 627400704\n"
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"total_active_file 661872640\n"
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"total_unevictable 3690496\n"
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"recent_rotated_anon 112807028\n"
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"recent_rotated_file 2547948\n"
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"recent_scanned_anon 113796164\n"
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"recent_scanned_file 8199863\n");
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MAKE_FILE("memory.swappiness", "60\n");
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MAKE_FILE("memory.usage_in_bytes", "1455321088\n");
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MAKE_FILE("memory.use_hierarchy", "0\n");
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} else if (STRPREFIX(controller, "freezer")) {
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MAKE_FILE("freezer.state", "THAWED");
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} else if (STRPREFIX(controller, "blkio")) {
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MAKE_FILE("blkio.io_merged",
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"8:0 Read 1100949\n"
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"8:0 Write 2248076\n"
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"8:0 Sync 63063\n"
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"8:0 Async 3285962\n"
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"8:0 Total 3349025\n");
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MAKE_FILE("blkio.io_queued",
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"8:0 Read 0\n"
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"8:0 Write 0\n"
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"8:0 Sync 0\n"
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"8:0 Async 0\n"
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"8:0 Total 0\n");
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MAKE_FILE("blkio.io_service_bytes",
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"8:0 Read 59542078464\n"
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"8:0 Write 397369182208\n"
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"8:0 Sync 234080922624\n"
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"8:0 Async 222830338048\n"
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"8:0 Total 456911260672\n");
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MAKE_FILE("blkio.io_serviced",
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"8:0 Read 3402504\n"
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"8:0 Write 14966516\n"
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"8:0 Sync 12064031\n"
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"8:0 Async 6304989\n"
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"8:0 Total 18369020\n");
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MAKE_FILE("blkio.io_service_time",
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"8:0 Read 10747537542349\n"
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"8:0 Write 9200028590575\n"
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"8:0 Sync 6449319855381\n"
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"8:0 Async 13498246277543\n"
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"8:0 Total 19947566132924\n");
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MAKE_FILE("blkio.io_wait_time",
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"8:0 Read 14687514824889\n"
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"8:0 Write 357748452187691\n"
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"8:0 Sync 55296974349413\n"
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"8:0 Async 317138992663167\n"
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"8:0 Total 372435967012580\n");
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MAKE_FILE("blkio.reset_stats", ""); /* Write only */
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MAKE_FILE("blkio.sectors", "8:0 892404806\n");
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MAKE_FILE("blkio.throttle.io_service_bytes",
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"8:0 Read 59542107136\n"
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"8:0 Write 411440480256\n"
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"8:0 Sync 248486822912\n"
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"8:0 Async 222495764480\n"
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"8:0 Total 470982587392\n");
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MAKE_FILE("blkio.throttle.io_serviced",
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"8:0 Read 4832583\n"
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"8:0 Write 36641903\n"
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"8:0 Sync 30723171\n"
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"8:0 Async 10751315\n"
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"8:0 Total 41474486\n");
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MAKE_FILE("blkio.throttle.read_bps_device", "");
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MAKE_FILE("blkio.throttle.read_iops_device", "");
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MAKE_FILE("blkio.throttle.write_bps_device", "");
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MAKE_FILE("blkio.throttle.write_iops_device", "");
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MAKE_FILE("blkio.time", "8:0 61019089\n");
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MAKE_FILE("blkio.weight", "1000\n");
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MAKE_FILE("blkio.weight_device", "");
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} else {
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errno = EINVAL;
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goto cleanup;
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}
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ret = 0;
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cleanup:
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return ret;
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}
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static void init_syms(void)
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{
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if (realfopen)
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return;
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# define LOAD_SYM(name) \
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do { \
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if (!(real ## name = dlsym(RTLD_NEXT, #name))) { \
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fprintf(stderr, "Cannot find real '%s' symbol\n", #name); \
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abort(); \
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} \
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} while (0)
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LOAD_SYM(fopen);
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LOAD_SYM(access);
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LOAD_SYM(mkdir);
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LOAD_SYM(open);
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}
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static void init_sysfs(void)
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{
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if (fakesysfsdir)
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return;
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if (!(fakesysfsdir = getenv("LIBVIRT_FAKE_SYSFS_DIR"))) {
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fprintf(stderr, "Missing LIBVIRT_FAKE_SYSFS_DIR env variable\n");
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abort();
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}
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# define MAKE_CONTROLLER(subpath) \
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do { \
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char *path; \
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if (asprintf(&path,"%s/%s", fakesysfsdir, subpath) < 0) \
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abort(); \
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if (make_controller(path, 0755) < 0) { \
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fprintf(stderr, "Cannot initialize %s\n", path); \
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abort(); \
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} \
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} while (0)
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MAKE_CONTROLLER("cpu");
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MAKE_CONTROLLER("cpuacct");
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MAKE_CONTROLLER("cpu,cpuacct");
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MAKE_CONTROLLER("cpu,cpuacct/system");
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MAKE_CONTROLLER("cpuset");
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MAKE_CONTROLLER("blkio");
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MAKE_CONTROLLER("memory");
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MAKE_CONTROLLER("freezer");
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}
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FILE *fopen(const char *path, const char *mode)
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{
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init_syms();
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if (STREQ(path, "/proc/mounts")) {
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if (STREQ(mode, "r")) {
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return fmemopen((void *)mounts, strlen(mounts), mode);
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} else {
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errno = EACCES;
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return NULL;
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}
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}
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if (STREQ(path, "/proc/self/cgroup")) {
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if (STREQ(mode, "r")) {
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return fmemopen((void *)cgroups, strlen(cgroups), mode);
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} else {
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errno = EACCES;
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return NULL;
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}
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}
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return realfopen(path, mode);
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}
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int access(const char *path, int mode)
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{
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int ret;
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init_syms();
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if (STRPREFIX(path, SYSFS_PREFIX)) {
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init_sysfs();
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char *newpath;
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if (asprintf(&newpath, "%s/%s",
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fakesysfsdir,
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path + strlen(SYSFS_PREFIX)) < 0) {
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errno = ENOMEM;
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return -1;
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}
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ret = realaccess(newpath, mode);
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free(newpath);
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} else {
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ret = realaccess(path, mode);
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}
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return ret;
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}
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int mkdir(const char *path, mode_t mode)
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{
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int ret;
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init_syms();
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if (STRPREFIX(path, SYSFS_PREFIX)) {
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init_sysfs();
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char *newpath;
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if (asprintf(&newpath, "%s/%s",
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fakesysfsdir,
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path + strlen(SYSFS_PREFIX)) < 0) {
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errno = ENOMEM;
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return -1;
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}
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ret = make_controller(newpath, mode);
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free(newpath);
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} else {
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ret = realmkdir(path, mode);
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}
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return ret;
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}
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int open(const char *path, int flags, ...)
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{
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int ret;
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char *newpath = NULL;
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init_syms();
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if (STRPREFIX(path, SYSFS_PREFIX)) {
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init_sysfs();
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if (asprintf(&newpath, "%s/%s",
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fakesysfsdir,
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path + strlen(SYSFS_PREFIX)) < 0) {
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errno = ENOMEM;
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return -1;
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}
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}
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if (flags & O_CREAT) {
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va_list ap;
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mode_t mode;
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va_start(ap, flags);
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mode = va_arg(ap, mode_t);
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va_end(ap);
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ret = realopen(newpath ? newpath : path, flags, mode);
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} else {
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ret = realopen(newpath ? newpath : path, flags);
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}
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free(newpath);
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|
return ret;
|
|
}
|
|
#else
|
|
/* Nothing to override on non-__linux__ platforms */
|
|
#endif
|