proc_loadavg: replace malloc() with asprintf() in calc_pid()

[mirror_lxcfs.git] / src / proc_loadavg.c

/* SPDX-License-Identifier: LGPL-2.1+ */

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#ifndef FUSE_USE_VERSION
#define FUSE_USE_VERSION 26
#endif

#define _FILE_OFFSET_BITS 64

#define __STDC_FORMAT_MACROS
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <fuse.h>
#include <inttypes.h>
#include <libgen.h>
#include <pthread.h>
#include <sched.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <wait.h>
#include <linux/magic.h>
#include <linux/sched.h>
#include <sys/epoll.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <sys/sysinfo.h>
#include <sys/vfs.h>

#include "bindings.h"
#include "config.h"
#include "cgroup_fuse.h"
#include "cgroups/cgroup.h"
#include "cgroups/cgroup_utils.h"
#include "memory_utils.h"
#include "utils.h"

/*
 * This parameter is used for proc_loadavg_read().
 * 1 means use loadavg, 0 means not use.
 */
static int loadavg = 0;

/* The function of hash table.*/
#define LOAD_SIZE 100 /*the size of hash_table */
#define FLUSH_TIME 5  /*the flush rate */
#define DEPTH_DIR 3   /*the depth of per cgroup */
/* The function of calculate loadavg .*/
#define FSHIFT          11              /* nr of bits of precision */
#define FIXED_1         (1 << FSHIFT)   /* 1.0 as fixed-point */
#define EXP_1           1884            /* 1/exp(5sec/1min) as fixed-point */
#define EXP_5           2014            /* 1/exp(5sec/5min) */
#define EXP_15          2037            /* 1/exp(5sec/15min) */
#define LOAD_INT(x) ((x) >> FSHIFT)
#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
static volatile sig_atomic_t loadavg_stop = 0;

struct load_node {
        /* cgroup */
        char *cg;
        /* Load averages */
        uint64_t avenrun[3];
        unsigned int run_pid;
        unsigned int total_pid;
        unsigned int last_pid;
        /* The file descriptor of the mounted cgroup */
        int cfd;
        struct load_node *next;
        struct load_node **pre;
};

struct load_head {
        /*
         * The lock is about insert load_node and refresh load_node.To the first
         * load_node of each hash bucket, insert and refresh in this hash bucket is
         * mutually exclusive.
         */
        pthread_mutex_t lock;
        /*
         * The rdlock is about read loadavg and delete load_node.To each hash
         * bucket, read and delete is mutually exclusive. But at the same time, we
         * allow paratactic read operation. This rdlock is at list level.
         */
        pthread_rwlock_t rdlock;
        /*
         * The rilock is about read loadavg and insert load_node.To the first
         * load_node of each hash bucket, read and insert is mutually exclusive.
         * But at the same time, we allow paratactic read operation.
         */
        pthread_rwlock_t rilock;
        struct load_node *next;
};

static struct load_head load_hash[LOAD_SIZE]; /* hash table */

/*
 * locate_node() finds special node. Not return NULL means success.
 * It should be noted that rdlock isn't unlocked at the end of code
 * because this function is used to read special node. Delete is not
 * allowed before read has ended.
 * unlock rdlock only in proc_loadavg_read().
 */
static struct load_node *locate_node(char *cg, int locate)
{
        struct load_node *f = NULL;
        int i = 0;

        pthread_rwlock_rdlock(&load_hash[locate].rilock);
        pthread_rwlock_rdlock(&load_hash[locate].rdlock);
        if (load_hash[locate].next == NULL) {
                pthread_rwlock_unlock(&load_hash[locate].rilock);
                return f;
        }
        f = load_hash[locate].next;
        pthread_rwlock_unlock(&load_hash[locate].rilock);
        while (f && ((i = strcmp(f->cg, cg)) != 0))
                f = f->next;
        return f;
}

static void insert_node(struct load_node **n, int locate)
{
        struct load_node *f;

        pthread_mutex_lock(&load_hash[locate].lock);
        pthread_rwlock_wrlock(&load_hash[locate].rilock);
        f = load_hash[locate].next;
        load_hash[locate].next = *n;

        (*n)->pre = &(load_hash[locate].next);
        if (f)
                f->pre = &((*n)->next);
        (*n)->next = f;
        pthread_mutex_unlock(&load_hash[locate].lock);
        pthread_rwlock_unlock(&load_hash[locate].rilock);
}

int calc_hash(const char *name)
{
        unsigned int hash = 0;
        unsigned int x = 0;

        /* ELFHash algorithm. */
        while (*name) {
                hash = (hash << 4) + *name++;
                x = hash & 0xf0000000;
                if (x != 0)
                        hash ^= (x >> 24);
                hash &= ~x;
        }

        return (hash & 0x7fffffff);
}

int proc_loadavg_read(char *buf, size_t size, off_t offset,
                      struct fuse_file_info *fi)
{
        __do_free char *cg = NULL;
        struct fuse_context *fc = fuse_get_context();
        struct file_info *d = INTTYPE_TO_PTR(fi->fh);
        pid_t initpid;
        ssize_t total_len = 0;
        char *cache = d->buf;
        struct load_node *n;
        int hash;
        int cfd;
        uint64_t a, b, c;

        if (offset) {
                int left;

                if (offset > d->size)
                        return -EINVAL;

                if (!d->cached)
                        return 0;

                left = d->size - offset;
                total_len = left > size ? size : left;
                memcpy(buf, cache + offset, total_len);

                return total_len;
        }
        if (!loadavg)
                return read_file_fuse("/proc/loadavg", buf, size, d);

        initpid = lookup_initpid_in_store(fc->pid);
        if (initpid <= 1 || is_shared_pidns(initpid))
                initpid = fc->pid;

        cg = get_pid_cgroup(initpid, "cpu");
        if (!cg)
                return read_file_fuse("/proc/loadavg", buf, size, d);

        prune_init_slice(cg);
        hash = calc_hash(cg) % LOAD_SIZE;
        n = locate_node(cg, hash);

        /* First time */
        if (n == NULL) {
                cfd = get_cgroup_fd("cpu");
                if (cfd < 0) {
                        /*
                         * In locate_node() above, pthread_rwlock_unlock() isn't used
                         * because delete is not allowed before read has ended.
                         */
                        pthread_rwlock_unlock(&load_hash[hash].rdlock);
                        return read_file_fuse("/proc/loadavg", buf, size, d);
                }

                do {
                        n = malloc(sizeof(struct load_node));
                } while (!n);

                do {
                        n->cg = malloc(strlen(cg) + 1);
                } while (!n->cg);

                strcpy(n->cg, cg);
                n->avenrun[0] = 0;
                n->avenrun[1] = 0;
                n->avenrun[2] = 0;
                n->run_pid = 0;
                n->total_pid = 1;
                n->last_pid = initpid;
                n->cfd = cfd;
                insert_node(&n, hash);
        }
        a = n->avenrun[0] + (FIXED_1 / 200);
        b = n->avenrun[1] + (FIXED_1 / 200);
        c = n->avenrun[2] + (FIXED_1 / 200);
        total_len = snprintf(d->buf, d->buflen,
                             "%lu.%02lu "
                             "%lu.%02lu "
                             "%lu.%02lu "
                             "%d/"
                             "%d "
                             "%d\n",
                             LOAD_INT(a),
                             LOAD_FRAC(a),
                             LOAD_INT(b),
                             LOAD_FRAC(b),
                             LOAD_INT(c),
                             LOAD_FRAC(c),
                             n->run_pid,
                             n->total_pid,
                             n->last_pid);
        pthread_rwlock_unlock(&load_hash[hash].rdlock);
        if (total_len < 0 || total_len >= d->buflen)
                return log_error(0, "Failed to write to cache");

        d->size = (int)total_len;
        d->cached = 1;

        if (total_len > size)
                total_len = size;

        memcpy(buf, d->buf, total_len);
        return total_len;
}

/*
 * Find the process pid from cgroup path.
 * eg:from /sys/fs/cgroup/cpu/docker/containerid/cgroup.procs to find the process pid.
 * @pid_buf : put pid to pid_buf.
 * @dpath : the path of cgroup. eg: /docker/containerid or /docker/containerid/child-cgroup ...
 * @depth : the depth of cgroup in container.
 * @sum : return the number of pid.
 * @cfd : the file descriptor of the mounted cgroup. eg: /sys/fs/cgroup/cpu
 */
static int calc_pid(char ***pid_buf, const char *dpath, int depth, int sum, int cfd)
{
        __do_free char *line = NULL, *path = NULL;
        __do_free void *fdopen_cache = NULL;
        __do_close int fd = -EBADF;
        __do_fclose FILE *f = NULL;
        __do_closedir DIR *dir = NULL;
        struct dirent *file;
        size_t linelen = 0;
        int pd;
        char **pid;

        /* path = dpath + "/cgroup.procs" + /0 */
        path = malloc(strlen(dpath) + 20);
        if (!path)
                return sum;

        strcpy(path, dpath);
        fd = openat(cfd, path, O_RDONLY | O_CLOEXEC);
        if (fd < 0)
                return sum;

        dir = fdopendir(fd);
        if (!dir)
                return sum;
        /* Transfer ownership to fdopendir(). */
        move_fd(fd);

        while (((file = readdir(dir)) != NULL) && depth > 0) {
                if (strcmp(file->d_name, ".") == 0)
                        continue;

                if (strcmp(file->d_name, "..") == 0)
                        continue;

                if (file->d_type == DT_DIR) {
                        __do_free char *path_dir = NULL;
                        int ret;

                        /* path + '/' + d_name +/0 */
                        ret = asprintf(&path_dir, "%s/%s", path, file->d_name);
                        if (ret < 0) {
                                path_dir = NULL;
                                return sum;
                        }

                        pd = depth - 1;
                        sum = calc_pid(pid_buf, path_dir, pd, sum, cfd);
                }
        }

        strcat(path, "/cgroup.procs");
        fd = openat(cfd, path, O_RDONLY | O_CLOEXEC);
        if (fd < 0)
                return sum;

        f = fdopen_cached(fd, "re", &fdopen_cache);
        if (!f)
                return sum;

        while (getline(&line, &linelen, f) != -1) {
                pid = realloc(*pid_buf, sizeof(char *) * (sum + 1));
                if (!pid)
                        return sum;
                *pid_buf = pid;

                *(*pid_buf + sum) = malloc(strlen(line) + 1);
                if (!*(*pid_buf + sum))
                        return sum;

                strcpy(*(*pid_buf + sum), line);
                sum++;
        }

        return sum;
}

/*
 * calc_load calculates the load according to the following formula:
 * load1 = load0 * exp + active * (1 - exp)
 *
 * @load1: the new loadavg.
 * @load0: the former loadavg.
 * @active: the total number of running pid at this moment.
 * @exp: the fixed-point defined in the beginning.
 */
static uint64_t calc_load(uint64_t load, uint64_t exp, uint64_t active)
{
        uint64_t newload;

        active = active > 0 ? active * FIXED_1 : 0;
        newload = load * exp + active * (FIXED_1 - exp);
        if (active >= load)
                newload += FIXED_1 - 1;

        return newload / FIXED_1;
}

/*
 * Return 0 means that container p->cg is closed.
 * Return -1 means that error occurred in refresh.
 * Positive num equals the total number of pid.
 */
static int refresh_load(struct load_node *p, const char *path)
{
        char **idbuf = NULL;
        char proc_path[STRLITERALLEN("/proc//task//status") +
                       2 * INTTYPE_TO_STRLEN(pid_t) + 1];
        int i, ret, run_pid = 0, total_pid = 0, last_pid = 0;
        size_t linelen = 0;
        int sum, length;
        struct dirent *file;

        idbuf = must_realloc(NULL, sizeof(char **));

        sum = calc_pid(&idbuf, path, DEPTH_DIR, 0, p->cfd);
        if (!sum)
                goto out;

        for (i = 0; i < sum; i++) {
                __do_closedir DIR *dp = NULL;

                length = strlen(idbuf[i]) - 1;
                idbuf[i][length] = '\0';

                ret = snprintf(proc_path, sizeof(proc_path), "/proc/%s/task", idbuf[i]);
                if (ret < 0 || (size_t)ret > sizeof(proc_path)) {
                        i = sum;
                        sum = -1;
                        lxcfs_error("%s\n", "snprintf() failed in refresh_load.");
                        goto err_out;
                }

                dp = opendir(proc_path);
                if (!dp) {
                        lxcfs_error("Failed to open \"%s\"", proc_path);
                        continue;
                }

                while ((file = readdir(dp)) != NULL) {
                        __do_free char *line = NULL;
                        __do_fclose FILE *f = NULL;

                        if (strcmp(file->d_name, ".") == 0)
                                continue;

                        if (strcmp(file->d_name, "..") == 0)
                                continue;

                        total_pid++;

                        /* We make the biggest pid become last_pid. */
                        ret = atof(file->d_name);
                        last_pid = (ret > last_pid) ? ret : last_pid;

                        ret = snprintf(proc_path, sizeof(proc_path),
                                       "/proc/%s/task/%s/status", idbuf[i], file->d_name);
                        if (ret < 0 || (size_t)ret > sizeof(proc_path)) {
                                i = sum;
                                sum = -1;
                                lxcfs_error("%s\n", "snprintf() failed in refresh_load.");
                                goto err_out;
                        }

                        f = fopen(proc_path, "re");
                        if (!f)
                                continue;

                        while (getline(&line, &linelen, f) != -1)
                                if ((line[0] == 'S') && (line[1] == 't'))
                                        break;

                        if ((line[7] == 'R') || (line[7] == 'D'))
                                run_pid++;
                }
        }

        /* Calculate the loadavg. */
        p->avenrun[0]   = calc_load(p->avenrun[0], EXP_1, run_pid);
        p->avenrun[1]   = calc_load(p->avenrun[1], EXP_5, run_pid);
        p->avenrun[2]   = calc_load(p->avenrun[2], EXP_15, run_pid);
        p->run_pid      = run_pid;
        p->total_pid    = total_pid;
        p->last_pid     = last_pid;

err_out:
        for (; i > 0; i--)
                free(idbuf[i - 1]);
out:
        free(idbuf);
        return sum;
}

/* Delete the load_node n and return the next node of it. */
static struct load_node *del_node(struct load_node *n, int locate)
{
        struct load_node *g;

        pthread_rwlock_wrlock(&load_hash[locate].rdlock);
        if (n->next == NULL) {
                *(n->pre) = NULL;
        } else {
                *(n->pre) = n->next;
                n->next->pre = n->pre;
        }
        g = n->next;
        free_disarm(n->cg);
        free_disarm(n);
        pthread_rwlock_unlock(&load_hash[locate].rdlock);
        return g;
}

/*
 * Traverse the hash table and update it.
 */
static void *load_begin(void *arg)
{

        int first_node, sum;
        struct load_node *f;
        clock_t time1, time2;

        for (;;) {
                if (loadavg_stop == 1)
                        return NULL;

                time1 = clock();
                for (int i = 0; i < LOAD_SIZE; i++) {
                        pthread_mutex_lock(&load_hash[i].lock);
                        if (load_hash[i].next == NULL) {
                                pthread_mutex_unlock(&load_hash[i].lock);
                                continue;
                        }

                        f = load_hash[i].next;
                        first_node = 1;
                        while (f) {
                                __do_free char *path = NULL;

                                path = must_make_path_relative(f->cg, NULL);

                                sum = refresh_load(f, path);
                                if (sum == 0)
                                        f = del_node(f, i);
                                else
                                        f = f->next;

                                /* load_hash[i].lock locks only on the first node.*/
                                if (first_node == 1) {
                                        first_node = 0;
                                        pthread_mutex_unlock(&load_hash[i].lock);
                                }
                        }
                }

                if (loadavg_stop == 1)
                        return NULL;

                time2 = clock();
                usleep(FLUSH_TIME * 1000000 -
                       (int)((time2 - time1) * 1000000 / CLOCKS_PER_SEC));
        }
}

/*
 * init_load initialize the hash table.
 * Return 0 on success, return -1 on failure.
 */
static int init_load(void)
{
        int i;
        int ret;

        for (i = 0; i < LOAD_SIZE; i++) {
                load_hash[i].next = NULL;
                ret = pthread_mutex_init(&load_hash[i].lock, NULL);
                if (ret) {
                        lxcfs_error("Failed to initialize lock");
                        goto out3;
                }

                ret = pthread_rwlock_init(&load_hash[i].rdlock, NULL);
                if (ret) {
                        lxcfs_error("Failed to initialize rdlock");
                        goto out2;
                }

                ret = pthread_rwlock_init(&load_hash[i].rilock, NULL);
                if (ret) {
                        lxcfs_error("Failed to initialize rilock");
                        goto out1;
                }
        }

        return 0;

out1:
        pthread_rwlock_destroy(&load_hash[i].rdlock);
out2:
        pthread_mutex_destroy(&load_hash[i].lock);
out3:
        while (i > 0) {
                i--;
                pthread_mutex_destroy(&load_hash[i].lock);
                pthread_rwlock_destroy(&load_hash[i].rdlock);
                pthread_rwlock_destroy(&load_hash[i].rilock);
        }

        return -1;
}

static void load_free(void)
{
        struct load_node *f, *p;

        for (int i = 0; i < LOAD_SIZE; i++) {
                pthread_mutex_lock(&load_hash[i].lock);
                pthread_rwlock_wrlock(&load_hash[i].rilock);
                pthread_rwlock_wrlock(&load_hash[i].rdlock);
                if (load_hash[i].next == NULL) {
                        pthread_mutex_unlock(&load_hash[i].lock);
                        pthread_mutex_destroy(&load_hash[i].lock);
                        pthread_rwlock_unlock(&load_hash[i].rilock);
                        pthread_rwlock_destroy(&load_hash[i].rilock);
                        pthread_rwlock_unlock(&load_hash[i].rdlock);
                        pthread_rwlock_destroy(&load_hash[i].rdlock);
                        continue;
                }

                for (f = load_hash[i].next; f;) {
                        free_disarm(f->cg);
                        p = f->next;
                        free_disarm(f);
                        f = p;
                }

                pthread_mutex_unlock(&load_hash[i].lock);
                pthread_mutex_destroy(&load_hash[i].lock);
                pthread_rwlock_unlock(&load_hash[i].rilock);
                pthread_rwlock_destroy(&load_hash[i].rilock);
                pthread_rwlock_unlock(&load_hash[i].rdlock);
                pthread_rwlock_destroy(&load_hash[i].rdlock);
        }
}

/* Return a positive number on success, return 0 on failure.*/
pthread_t load_daemon(int load_use)
{
        int ret;
        pthread_t pid;

        ret = init_load();
        if (ret == -1)
                return log_error(0, "Initialize hash_table fails in load_daemon!");

        ret = pthread_create(&pid, NULL, load_begin, NULL);
        if (ret != 0) {
                load_free();
                return log_error(0, "Create pthread fails in load_daemon!");
        }

        /* use loadavg, here loadavg = 1*/
        loadavg = load_use;
        return pid;
}

/* Returns 0 on success. */
int stop_load_daemon(pthread_t pid)
{
        int s;

        /* Signal the thread to gracefully stop */
        loadavg_stop = 1;

        s = pthread_join(pid, NULL); /* Make sure sub thread has been canceled. */
        if (s)
                return log_error(-1, "stop_load_daemon error: failed to join");

        load_free();
        loadavg_stop = 0;

        return 0;
}