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434 lines
11 KiB
434 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0 |
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#define _GNU_SOURCE |
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#include <sched.h> |
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#include <sys/mount.h> |
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#include <sys/stat.h> |
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#include <sys/types.h> |
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#include <linux/limits.h> |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <linux/sched.h> |
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#include <fcntl.h> |
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#include <unistd.h> |
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#include <ftw.h> |
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#include "cgroup_helpers.h" |
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/* |
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* To avoid relying on the system setup, when setup_cgroup_env is called |
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* we create a new mount namespace, and cgroup namespace. The cgroupv2 |
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* root is mounted at CGROUP_MOUNT_PATH. Unfortunately, most people don't |
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* have cgroupv2 enabled at this point in time. It's easier to create our |
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* own mount namespace and manage it ourselves. We assume /mnt exists. |
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* |
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* Related cgroupv1 helpers are named *classid*(), since we only use the |
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* net_cls controller for tagging net_cls.classid. We assume the default |
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* mount under /sys/fs/cgroup/net_cls, which should be the case for the |
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* vast majority of users. |
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*/ |
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#define WALK_FD_LIMIT 16 |
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#define CGROUP_MOUNT_PATH "/mnt" |
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#define CGROUP_MOUNT_DFLT "/sys/fs/cgroup" |
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#define NETCLS_MOUNT_PATH CGROUP_MOUNT_DFLT "/net_cls" |
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#define CGROUP_WORK_DIR "/cgroup-test-work-dir" |
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#define format_cgroup_path(buf, path) \ |
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snprintf(buf, sizeof(buf), "%s%s%s", CGROUP_MOUNT_PATH, \ |
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CGROUP_WORK_DIR, path) |
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#define format_classid_path(buf) \ |
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snprintf(buf, sizeof(buf), "%s%s", NETCLS_MOUNT_PATH, \ |
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CGROUP_WORK_DIR) |
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/** |
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* enable_all_controllers() - Enable all available cgroup v2 controllers |
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* |
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* Enable all available cgroup v2 controllers in order to increase |
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* the code coverage. |
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* |
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* If successful, 0 is returned. |
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*/ |
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static int enable_all_controllers(char *cgroup_path) |
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{ |
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char path[PATH_MAX + 1]; |
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char buf[PATH_MAX]; |
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char *c, *c2; |
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int fd, cfd; |
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ssize_t len; |
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snprintf(path, sizeof(path), "%s/cgroup.controllers", cgroup_path); |
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fd = open(path, O_RDONLY); |
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if (fd < 0) { |
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log_err("Opening cgroup.controllers: %s", path); |
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return 1; |
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} |
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len = read(fd, buf, sizeof(buf) - 1); |
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if (len < 0) { |
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close(fd); |
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log_err("Reading cgroup.controllers: %s", path); |
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return 1; |
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} |
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buf[len] = 0; |
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close(fd); |
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/* No controllers available? We're probably on cgroup v1. */ |
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if (len == 0) |
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return 0; |
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snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path); |
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cfd = open(path, O_RDWR); |
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if (cfd < 0) { |
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log_err("Opening cgroup.subtree_control: %s", path); |
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return 1; |
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} |
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for (c = strtok_r(buf, " ", &c2); c; c = strtok_r(NULL, " ", &c2)) { |
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if (dprintf(cfd, "+%s\n", c) <= 0) { |
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log_err("Enabling controller %s: %s", c, path); |
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close(cfd); |
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return 1; |
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} |
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} |
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close(cfd); |
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return 0; |
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} |
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/** |
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* setup_cgroup_environment() - Setup the cgroup environment |
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* |
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* After calling this function, cleanup_cgroup_environment should be called |
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* once testing is complete. |
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* |
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* This function will print an error to stderr and return 1 if it is unable |
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* to setup the cgroup environment. If setup is successful, 0 is returned. |
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*/ |
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int setup_cgroup_environment(void) |
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{ |
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char cgroup_workdir[PATH_MAX - 24]; |
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format_cgroup_path(cgroup_workdir, ""); |
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if (unshare(CLONE_NEWNS)) { |
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log_err("unshare"); |
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return 1; |
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} |
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if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL)) { |
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log_err("mount fakeroot"); |
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return 1; |
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} |
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if (mount("none", CGROUP_MOUNT_PATH, "cgroup2", 0, NULL) && errno != EBUSY) { |
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log_err("mount cgroup2"); |
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return 1; |
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} |
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/* Cleanup existing failed runs, now that the environment is setup */ |
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cleanup_cgroup_environment(); |
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if (mkdir(cgroup_workdir, 0777) && errno != EEXIST) { |
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log_err("mkdir cgroup work dir"); |
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return 1; |
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} |
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if (enable_all_controllers(cgroup_workdir)) |
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return 1; |
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return 0; |
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} |
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static int nftwfunc(const char *filename, const struct stat *statptr, |
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int fileflags, struct FTW *pfwt) |
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{ |
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if ((fileflags & FTW_D) && rmdir(filename)) |
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log_err("Removing cgroup: %s", filename); |
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return 0; |
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} |
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static int join_cgroup_from_top(const char *cgroup_path) |
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{ |
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char cgroup_procs_path[PATH_MAX + 1]; |
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pid_t pid = getpid(); |
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int fd, rc = 0; |
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snprintf(cgroup_procs_path, sizeof(cgroup_procs_path), |
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"%s/cgroup.procs", cgroup_path); |
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fd = open(cgroup_procs_path, O_WRONLY); |
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if (fd < 0) { |
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log_err("Opening Cgroup Procs: %s", cgroup_procs_path); |
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return 1; |
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} |
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if (dprintf(fd, "%d\n", pid) < 0) { |
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log_err("Joining Cgroup"); |
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rc = 1; |
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} |
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close(fd); |
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return rc; |
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} |
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/** |
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* join_cgroup() - Join a cgroup |
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* @path: The cgroup path, relative to the workdir, to join |
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* |
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* This function expects a cgroup to already be created, relative to the cgroup |
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* work dir, and it joins it. For example, passing "/my-cgroup" as the path |
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* would actually put the calling process into the cgroup |
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* "/cgroup-test-work-dir/my-cgroup" |
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* |
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* On success, it returns 0, otherwise on failure it returns 1. |
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*/ |
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int join_cgroup(const char *path) |
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{ |
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char cgroup_path[PATH_MAX + 1]; |
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format_cgroup_path(cgroup_path, path); |
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return join_cgroup_from_top(cgroup_path); |
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} |
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/** |
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* cleanup_cgroup_environment() - Cleanup Cgroup Testing Environment |
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* |
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* This is an idempotent function to delete all temporary cgroups that |
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* have been created during the test, including the cgroup testing work |
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* directory. |
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* |
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* At call time, it moves the calling process to the root cgroup, and then |
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* runs the deletion process. It is idempotent, and should not fail, unless |
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* a process is lingering. |
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* |
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* On failure, it will print an error to stderr, and try to continue. |
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*/ |
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void cleanup_cgroup_environment(void) |
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{ |
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char cgroup_workdir[PATH_MAX + 1]; |
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format_cgroup_path(cgroup_workdir, ""); |
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join_cgroup_from_top(CGROUP_MOUNT_PATH); |
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nftw(cgroup_workdir, nftwfunc, WALK_FD_LIMIT, FTW_DEPTH | FTW_MOUNT); |
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} |
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/** |
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* create_and_get_cgroup() - Create a cgroup, relative to workdir, and get the FD |
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* @path: The cgroup path, relative to the workdir, to join |
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* |
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* This function creates a cgroup under the top level workdir and returns the |
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* file descriptor. It is idempotent. |
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* |
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* On success, it returns the file descriptor. On failure it returns -1. |
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* If there is a failure, it prints the error to stderr. |
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*/ |
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int create_and_get_cgroup(const char *path) |
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{ |
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char cgroup_path[PATH_MAX + 1]; |
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int fd; |
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format_cgroup_path(cgroup_path, path); |
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if (mkdir(cgroup_path, 0777) && errno != EEXIST) { |
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log_err("mkdiring cgroup %s .. %s", path, cgroup_path); |
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return -1; |
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} |
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fd = open(cgroup_path, O_RDONLY); |
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if (fd < 0) { |
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log_err("Opening Cgroup"); |
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return -1; |
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} |
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return fd; |
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} |
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/** |
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* get_cgroup_id() - Get cgroup id for a particular cgroup path |
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* @path: The cgroup path, relative to the workdir, to join |
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* |
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* On success, it returns the cgroup id. On failure it returns 0, |
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* which is an invalid cgroup id. |
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* If there is a failure, it prints the error to stderr. |
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*/ |
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unsigned long long get_cgroup_id(const char *path) |
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{ |
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int dirfd, err, flags, mount_id, fhsize; |
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union { |
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unsigned long long cgid; |
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unsigned char raw_bytes[8]; |
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} id; |
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char cgroup_workdir[PATH_MAX + 1]; |
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struct file_handle *fhp, *fhp2; |
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unsigned long long ret = 0; |
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format_cgroup_path(cgroup_workdir, path); |
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dirfd = AT_FDCWD; |
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flags = 0; |
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fhsize = sizeof(*fhp); |
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fhp = calloc(1, fhsize); |
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if (!fhp) { |
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log_err("calloc"); |
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return 0; |
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} |
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err = name_to_handle_at(dirfd, cgroup_workdir, fhp, &mount_id, flags); |
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if (err >= 0 || fhp->handle_bytes != 8) { |
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log_err("name_to_handle_at"); |
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goto free_mem; |
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} |
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fhsize = sizeof(struct file_handle) + fhp->handle_bytes; |
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fhp2 = realloc(fhp, fhsize); |
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if (!fhp2) { |
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log_err("realloc"); |
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goto free_mem; |
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} |
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err = name_to_handle_at(dirfd, cgroup_workdir, fhp2, &mount_id, flags); |
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fhp = fhp2; |
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if (err < 0) { |
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log_err("name_to_handle_at"); |
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goto free_mem; |
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} |
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memcpy(id.raw_bytes, fhp->f_handle, 8); |
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ret = id.cgid; |
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free_mem: |
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free(fhp); |
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return ret; |
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} |
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int cgroup_setup_and_join(const char *path) { |
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int cg_fd; |
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if (setup_cgroup_environment()) { |
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fprintf(stderr, "Failed to setup cgroup environment\n"); |
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return -EINVAL; |
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} |
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cg_fd = create_and_get_cgroup(path); |
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if (cg_fd < 0) { |
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fprintf(stderr, "Failed to create test cgroup\n"); |
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cleanup_cgroup_environment(); |
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return cg_fd; |
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} |
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if (join_cgroup(path)) { |
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fprintf(stderr, "Failed to join cgroup\n"); |
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cleanup_cgroup_environment(); |
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return -EINVAL; |
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} |
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return cg_fd; |
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} |
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/** |
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* setup_classid_environment() - Setup the cgroupv1 net_cls environment |
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* |
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* After calling this function, cleanup_classid_environment should be called |
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* once testing is complete. |
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* |
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* This function will print an error to stderr and return 1 if it is unable |
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* to setup the cgroup environment. If setup is successful, 0 is returned. |
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*/ |
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int setup_classid_environment(void) |
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{ |
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char cgroup_workdir[PATH_MAX + 1]; |
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format_classid_path(cgroup_workdir); |
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if (mount("tmpfs", CGROUP_MOUNT_DFLT, "tmpfs", 0, NULL) && |
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errno != EBUSY) { |
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log_err("mount cgroup base"); |
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return 1; |
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} |
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if (mkdir(NETCLS_MOUNT_PATH, 0777) && errno != EEXIST) { |
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log_err("mkdir cgroup net_cls"); |
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return 1; |
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} |
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if (mount("net_cls", NETCLS_MOUNT_PATH, "cgroup", 0, "net_cls") && |
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errno != EBUSY) { |
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log_err("mount cgroup net_cls"); |
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return 1; |
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} |
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cleanup_classid_environment(); |
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if (mkdir(cgroup_workdir, 0777) && errno != EEXIST) { |
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log_err("mkdir cgroup work dir"); |
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return 1; |
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} |
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return 0; |
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} |
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/** |
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* set_classid() - Set a cgroupv1 net_cls classid |
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* @id: the numeric classid |
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* |
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* Writes the passed classid into the cgroup work dir's net_cls.classid |
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* file in order to later on trigger socket tagging. |
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* |
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* On success, it returns 0, otherwise on failure it returns 1. If there |
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* is a failure, it prints the error to stderr. |
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*/ |
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int set_classid(unsigned int id) |
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{ |
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char cgroup_workdir[PATH_MAX - 42]; |
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char cgroup_classid_path[PATH_MAX + 1]; |
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int fd, rc = 0; |
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format_classid_path(cgroup_workdir); |
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snprintf(cgroup_classid_path, sizeof(cgroup_classid_path), |
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"%s/net_cls.classid", cgroup_workdir); |
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fd = open(cgroup_classid_path, O_WRONLY); |
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if (fd < 0) { |
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log_err("Opening cgroup classid: %s", cgroup_classid_path); |
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return 1; |
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} |
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if (dprintf(fd, "%u\n", id) < 0) { |
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log_err("Setting cgroup classid"); |
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rc = 1; |
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} |
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close(fd); |
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return rc; |
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} |
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/** |
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* join_classid() - Join a cgroupv1 net_cls classid |
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* |
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* This function expects the cgroup work dir to be already created, as we |
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* join it here. This causes the process sockets to be tagged with the given |
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* net_cls classid. |
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* |
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* On success, it returns 0, otherwise on failure it returns 1. |
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*/ |
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int join_classid(void) |
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{ |
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char cgroup_workdir[PATH_MAX + 1]; |
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format_classid_path(cgroup_workdir); |
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return join_cgroup_from_top(cgroup_workdir); |
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} |
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/** |
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* cleanup_classid_environment() - Cleanup the cgroupv1 net_cls environment |
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* |
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* At call time, it moves the calling process to the root cgroup, and then |
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* runs the deletion process. |
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* |
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* On failure, it will print an error to stderr, and try to continue. |
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*/ |
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void cleanup_classid_environment(void) |
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{ |
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char cgroup_workdir[PATH_MAX + 1]; |
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format_classid_path(cgroup_workdir); |
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join_cgroup_from_top(NETCLS_MOUNT_PATH); |
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nftw(cgroup_workdir, nftwfunc, WALK_FD_LIMIT, FTW_DEPTH | FTW_MOUNT); |
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}
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