#pragma once
/*
 * diskstats.h -- sum the sector counters of the physical disks listed in
 * /proc/diskstats (node_information.c's io metric).
 */
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>

/* A whole physical disk has /sys/block/<name>/device (a link to its
 * hardware). Partitions are not in /sys/block, and loop, ram, zram, dm-
 * and md devices have no `device` -- counting dm/md would also count the
 * same I/O twice, once more through their member disks. */
static inline int diskstats_is_physical(const char* sysblock, const char* name)
{
    char        path[512];
    struct stat st;

    if (strchr(name, '/') != NULL || name[0] == '.') {
        return 0;
    }
    snprintf(path, sizeof(path), "%s/%s/device", sysblock, name);
    return stat(path, &st) == 0;
}

/* Sum sectors read/written over the physical disks in `fp` (a
 * /proc/diskstats stream). `sysblock` is the /sys/block directory.
 * Returns the number of disks counted.
 *
 * bug-1872: this used to guess from the name (skip names ending in a digit
 * or containing 'p'), which dropped every NVMe disk (nvme0n1), mmc disks
 * (mmcblk0) and even sdp. */
static inline int diskstats_sum_physical(FILE* fp, const char* sysblock,
                                         unsigned long long* sectors_read,
                                         unsigned long long* sectors_written)
{
    char line[512];
    int  ndisks = 0;

    *sectors_read    = 0;
    *sectors_written = 0;

    while (fgets(line, sizeof(line), fp)) {
        int                major, minor;
        char               name[64];
        unsigned long long rc, rm, rd, rt, wc, wm, wr, wt, inprog, iot, wiot;

        if (sscanf(line,
                   "%d %d %63s %llu %llu %llu %llu %llu %llu %llu %llu %llu "
                   "%llu %llu",
                   &major, &minor, name, &rc, &rm, &rd, &rt, &wc, &wm, &wr, &wt,
                   &inprog, &iot, &wiot)
            < 14) {
            continue;
        }
        if (!diskstats_is_physical(sysblock, name)) {
            continue;
        }
        *sectors_read += rd;
        *sectors_written += wr;
        ndisks++;
    }
    return ndisks;
}