// SPDX-License-Identifier: GPL-2.0
/* procacct.c
 *
 * Demonstrator of fetching resource data on task exit, as a way
 * to accumulate accurate program resource usage statistics, without
 * prior identification of the programs. For that, the fields for
 * device and inode of the program executable binary file are also
 * extracted in addition to the command string.
 *
 * The TGID together with the PID and the AGROUP flag allow
 * identification of threads in a process and single-threaded processes.
 * The ac_tgetime field gives proper whole-process walltime.
 *
 * Written (changed) by Thomas Orgis, University of Hamburg in 2022
 *
 * This is a cheap derivation (inheriting the style) of getdelays.c:
 *
 * Utility to get per-pid and per-tgid delay accounting statistics
 * Also illustrates usage of the taskstats interface
 *
 * Copyright (C) Shailabh Nagar, IBM Corp. 2005
 * Copyright (C) Balbir Singh, IBM Corp. 2006
 * Copyright (c) Jay Lan, SGI. 2006
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <poll.h>
#include <string.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <signal.h>

#include <linux/genetlink.h>
#include <linux/acct.h>
#include <linux/taskstats.h>
#include <linux/kdev_t.h>

/*
 * Generic macros for dealing with netlink sockets. Might be duplicated
 * elsewhere. It is recommended that commercial grade applications use
 * libnl or libnetlink and use the interfaces provided by the library
 */
#define GENLMSG_DATA(glh)       ((void *)(NLMSG_DATA(glh) + GENL_HDRLEN))
#define GENLMSG_PAYLOAD(glh)    (NLMSG_PAYLOAD(glh, 0) - GENL_HDRLEN)
#define NLA_DATA(na)            ((void *)((char *)(na) + NLA_HDRLEN))
#define NLA_PAYLOAD(len)        (len - NLA_HDRLEN)

#define err(code, fmt, arg...)                  \
        do {                                    \
                fprintf(stderr, fmt, ##arg);    \
                exit(code);                     \
        } while (0)

int rcvbufsz;
char name[100];
int dbg;
int print_delays;
int print_io_accounting;
int print_task_context_switch_counts;

#define PRINTF(fmt, arg...) {                   \
                if (dbg) {                      \
                        printf(fmt, ##arg);     \
                }                               \
        }

/* Maximum size of response requested or message sent */
#define MAX_MSG_SIZE    1024
/* Maximum number of cpus expected to be specified in a cpumask */
#define MAX_CPUS        32

struct msgtemplate {
        struct nlmsghdr n;
        struct genlmsghdr g;
        char buf[MAX_MSG_SIZE];
};

char cpumask[100+6*MAX_CPUS];

static void usage(void)
{
        fprintf(stderr, "procacct [-v] [-w logfile] [-r bufsize] [-m cpumask]\n");
        fprintf(stderr, "  -v: debug on\n");
}

/*
 * Create a raw netlink socket and bind
 */
static int create_nl_socket(int protocol)
{
        int fd;
        struct sockaddr_nl local;

        fd = socket(AF_NETLINK, SOCK_RAW, protocol);
        if (fd < 0)
                return -1;

        if (rcvbufsz)
                if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF,
                                &rcvbufsz, sizeof(rcvbufsz)) < 0) {
                        fprintf(stderr, "Unable to set socket rcv buf size to %d\n",
                                rcvbufsz);
                        goto error;
                }

        memset(&local, 0, sizeof(local));
        local.nl_family = AF_NETLINK;

        if (bind(fd, (struct sockaddr *) &local, sizeof(local)) < 0)
                goto error;

        return fd;
error:
        close(fd);
        return -1;
}


static int send_cmd(int sd, __u16 nlmsg_type, __u32 nlmsg_pid,
             __u8 genl_cmd, __u16 nla_type,
             void *nla_data, int nla_len)
{
        struct nlattr *na;
        struct sockaddr_nl nladdr;
        int r, buflen;
        char *buf;

        struct msgtemplate msg;

        msg.n.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
        msg.n.nlmsg_type = nlmsg_type;
        msg.n.nlmsg_flags = NLM_F_REQUEST;
        msg.n.nlmsg_seq = 0;
        msg.n.nlmsg_pid = nlmsg_pid;
        msg.g.cmd = genl_cmd;
        msg.g.version = 0x1;
        na = (struct nlattr *) GENLMSG_DATA(&msg);
        na->nla_type = nla_type;
        na->nla_len = nla_len + 1 + NLA_HDRLEN;
        memcpy(NLA_DATA(na), nla_data, nla_len);
        msg.n.nlmsg_len += NLMSG_ALIGN(na->nla_len);

        buf = (char *) &msg;
        buflen = msg.n.nlmsg_len;
        memset(&nladdr, 0, sizeof(nladdr));
        nladdr.nl_family = AF_NETLINK;
        while ((r = sendto(sd, buf, buflen, 0, (struct sockaddr *) &nladdr,
                           sizeof(nladdr))) < buflen) {
                if (r > 0) {
                        buf += r;
                        buflen -= r;
                } else if (errno != EAGAIN)
                        return -1;
        }
        return 0;
}


/*
 * Probe the controller in genetlink to find the family id
 * for the TASKSTATS family
 */
static int get_family_id(int sd)
{
        struct {
                struct nlmsghdr n;
                struct genlmsghdr g;
                char buf[256];
        } ans;

        int id = 0, rc;
        struct nlattr *na;
        int rep_len;

        strcpy(name, TASKSTATS_GENL_NAME);
        rc = send_cmd(sd, GENL_ID_CTRL, getpid(), CTRL_CMD_GETFAMILY,
                        CTRL_ATTR_FAMILY_NAME, (void *)name,
                        strlen(TASKSTATS_GENL_NAME)+1);
        if (rc < 0)
                return 0;       /* sendto() failure? */

        rep_len = recv(sd, &ans, sizeof(ans), 0);
        if (ans.n.nlmsg_type == NLMSG_ERROR ||
            (rep_len < 0) || !NLMSG_OK((&ans.n), rep_len))
                return 0;

        na = (struct nlattr *) GENLMSG_DATA(&ans);
        na = (struct nlattr *) ((char *) na + NLA_ALIGN(na->nla_len));
        if (na->nla_type == CTRL_ATTR_FAMILY_ID)
                id = *(__u16 *) NLA_DATA(na);

        return id;
}

#define average_ms(t, c) (t / 1000000ULL / (c ? c : 1))

static void print_procacct(struct taskstats *t)
{
        /* First letter: T is a mere thread, G the last in a group, U  unknown. */
        printf(
                "%c pid=%lu tgid=%lu uid=%lu wall=%llu gwall=%llu cpu=%llu vmpeak=%llu rsspeak=%llu dev=%lu:%lu inode=%llu comm=%s\n"
        ,       t->version >= 12 ? (t->ac_flag & AGROUP ? 'P' : 'T') : '?'
        ,       (unsigned long)t->ac_pid
        ,       (unsigned long)(t->version >= 12 ? t->ac_tgid : 0)
        ,       (unsigned long)t->ac_uid
        ,       (unsigned long long)t->ac_etime
        ,       (unsigned long long)(t->version >= 12 ? t->ac_tgetime : 0)
        ,       (unsigned long long)(t->ac_utime+t->ac_stime)
        ,       (unsigned long long)t->hiwater_vm
        ,       (unsigned long long)t->hiwater_rss
        ,       (unsigned long)(t->version >= 12 ? MAJOR(t->ac_exe_dev) : 0)
        ,       (unsigned long)(t->version >= 12 ? MINOR(t->ac_exe_dev) : 0)
        ,       (unsigned long long)(t->version >= 12 ? t->ac_exe_inode : 0)
        ,       t->ac_comm
        );
}

void handle_aggr(int mother, struct nlattr *na, int fd)
{
        int aggr_len = NLA_PAYLOAD(na->nla_len);
        int len2 = 0;
        pid_t rtid = 0;

        na = (struct nlattr *) NLA_DATA(na);
        while (len2 < aggr_len) {
                switch (na->nla_type) {
                case TASKSTATS_TYPE_PID:
                        rtid = *(int *) NLA_DATA(na);
                        PRINTF("PID\t%d\n", rtid);
                        break;
                case TASKSTATS_TYPE_TGID:
                        rtid = *(int *) NLA_DATA(na);
                        PRINTF("TGID\t%d\n", rtid);
                        break;
                case TASKSTATS_TYPE_STATS:
                        if (mother == TASKSTATS_TYPE_AGGR_PID)
                                print_procacct((struct taskstats *) NLA_DATA(na));
                        if (fd) {
                                if (write(fd, NLA_DATA(na), na->nla_len) < 0)
                                        err(1, "write error\n");
                        }
                        break;
                case TASKSTATS_TYPE_NULL:
                        break;
                default:
                        fprintf(stderr, "Unknown nested nla_type %d\n",
                                na->nla_type);
                        break;
                }
                len2 += NLA_ALIGN(na->nla_len);
                na = (struct nlattr *)((char *)na +
                                                 NLA_ALIGN(na->nla_len));
        }
}

int main(int argc, char *argv[])
{
        int c, rc, rep_len;
        __u16 id;
        __u32 mypid;

        struct nlattr *na;
        int nl_sd = -1;
        int len = 0;

        int fd = 0;
        int write_file = 0;
        int maskset = 0;
        char *logfile = NULL;
        int cfd = 0;

        struct msgtemplate msg;

        while (1) {
                c = getopt(argc, argv, "m:vr:w:");
                if (c < 0)
                        break;

                switch (c) {
                case 'w':
                        logfile = strdup(optarg);
                        printf("write to file %s\n", logfile);
                        write_file = 1;
                        break;
                case 'r':
                        rcvbufsz = atoi(optarg);
                        printf("receive buf size %d\n", rcvbufsz);
                        if (rcvbufsz < 0)
                                err(1, "Invalid rcv buf size\n");
                        break;
                case 'm':
                        strncpy(cpumask, optarg, sizeof(cpumask));
                        cpumask[sizeof(cpumask) - 1] = '\0';
                        maskset = 1;
                        break;
                case 'v':
                        printf("debug on\n");
                        dbg = 1;
                        break;
                default:
                        usage();
                        exit(-1);
                }
        }
        if (!maskset) {
                maskset = 1;
                strncpy(cpumask, "1", sizeof(cpumask));
                cpumask[sizeof(cpumask) - 1] = '\0';
        }
        printf("cpumask %s maskset %d\n", cpumask, maskset);

        if (write_file) {
                fd = open(logfile, O_WRONLY | O_CREAT | O_TRUNC, 0644);
                if (fd == -1) {
                        perror("Cannot open output file\n");
                        exit(1);
                }
        }

        nl_sd = create_nl_socket(NETLINK_GENERIC);
        if (nl_sd < 0)
                err(1, "error creating Netlink socket\n");

        mypid = getpid();
        id = get_family_id(nl_sd);
        if (!id) {
                fprintf(stderr, "Error getting family id, errno %d\n", errno);
                goto err;
        }
        PRINTF("family id %d\n", id);

        if (maskset) {
                rc = send_cmd(nl_sd, id, mypid, TASKSTATS_CMD_GET,
                              TASKSTATS_CMD_ATTR_REGISTER_CPUMASK,
                              &cpumask, strlen(cpumask) + 1);
                PRINTF("Sent register cpumask, retval %d\n", rc);
                if (rc < 0) {
                        fprintf(stderr, "error sending register cpumask\n");
                        goto err;
                }
        }

        do {
                rep_len = recv(nl_sd, &msg, sizeof(msg), 0);
                PRINTF("received %d bytes\n", rep_len);

                if (rep_len < 0) {
                        fprintf(stderr, "nonfatal reply error: errno %d\n",
                                errno);
                        continue;
                }
                if (msg.n.nlmsg_type == NLMSG_ERROR ||
                    !NLMSG_OK((&msg.n), rep_len)) {
                        struct nlmsgerr *err = NLMSG_DATA(&msg);

                        fprintf(stderr, "fatal reply error,  errno %d\n",
                                err->error);
                        goto done;
                }

                PRINTF("nlmsghdr size=%zu, nlmsg_len=%d, rep_len=%d\n",
                       sizeof(struct nlmsghdr), msg.n.nlmsg_len, rep_len);


                rep_len = GENLMSG_PAYLOAD(&msg.n);

                na = (struct nlattr *) GENLMSG_DATA(&msg);
                len = 0;
                while (len < rep_len) {
                        len += NLA_ALIGN(na->nla_len);
                        int mother = na->nla_type;

                        PRINTF("mother=%i\n", mother);
                        switch (na->nla_type) {
                        case TASKSTATS_TYPE_AGGR_PID:
                        case TASKSTATS_TYPE_AGGR_TGID:
                                /* For nested attributes, na follows */
                                handle_aggr(mother, na, fd);
                                break;
                        default:
                                fprintf(stderr, "Unexpected nla_type %d\n",
                                        na->nla_type);
                        case TASKSTATS_TYPE_NULL:
                                break;
                        }
                        na = (struct nlattr *) (GENLMSG_DATA(&msg) + len);
                }
        } while (1);
done:
        if (maskset) {
                rc = send_cmd(nl_sd, id, mypid, TASKSTATS_CMD_GET,
                              TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK,
                              &cpumask, strlen(cpumask) + 1);
                printf("Sent deregister mask, retval %d\n", rc);
                if (rc < 0)
                        err(rc, "error sending deregister cpumask\n");
        }
err:
        close(nl_sd);
        if (fd)
                close(fd);
        if (cfd)
                close(cfd);
        return 0;
}