// SPDX-License-Identifier: GPL-2.0-only
/*
 *  (C) 2004-2009  Dominik Brodowski <linux@dominikbrodowski.de>
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>

#include "cpupower.h"
#include "cpupower_intern.h"

unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
{
        int fd;
        ssize_t numread;

        fd = open(path, O_RDONLY);
        if (fd == -1)
                return 0;

        numread = read(fd, buf, buflen - 1);
        if (numread < 1) {
                close(fd);
                return 0;
        }

        buf[numread] = '\0';
        close(fd);

        return (unsigned int) numread;
}

/*
 * Detect whether a CPU is online
 *
 * Returns:
 *     1 -> if CPU is online
 *     0 -> if CPU is offline
 *     negative errno values in error case
 */
int cpupower_is_cpu_online(unsigned int cpu)
{
        char path[SYSFS_PATH_MAX];
        int fd;
        ssize_t numread;
        unsigned long long value;
        char linebuf[MAX_LINE_LEN];
        char *endp;
        struct stat statbuf;

        snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);

        if (stat(path, &statbuf) != 0)
                return 0;

        /*
         * kernel without CONFIG_HOTPLUG_CPU
         * -> cpuX directory exists, but not cpuX/online file
         */
        snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
        if (stat(path, &statbuf) != 0)
                return 1;

        fd = open(path, O_RDONLY);
        if (fd == -1)
                return -errno;

        numread = read(fd, linebuf, MAX_LINE_LEN - 1);
        if (numread < 1) {
                close(fd);
                return -EIO;
        }
        linebuf[numread] = '\0';
        close(fd);

        value = strtoull(linebuf, &endp, 0);
        if (value > 1)
                return -EINVAL;

        return value;
}

/* returns -1 on failure, 0 on success */
static int sysfs_topology_read_file(unsigned int cpu, const char *fname, int *result)
{
        char linebuf[MAX_LINE_LEN];
        char *endp;
        char path[SYSFS_PATH_MAX];

        snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",
                         cpu, fname);
        if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
                return -1;
        *result = strtol(linebuf, &endp, 0);
        if (endp == linebuf || errno == ERANGE)
                return -1;
        return 0;
}

static int __compare(const void *t1, const void *t2)
{
        struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;
        struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;
        if (top1->pkg < top2->pkg)
                return -1;
        else if (top1->pkg > top2->pkg)
                return 1;
        else if (top1->core < top2->core)
                return -1;
        else if (top1->core > top2->core)
                return 1;
        else if (top1->cpu < top2->cpu)
                return -1;
        else if (top1->cpu > top2->cpu)
                return 1;
        else
                return 0;
}

/*
 * Returns amount of cpus, negative on error, cpu_top must be
 * passed to cpu_topology_release to free resources
 *
 * Array is sorted after ->pkg, ->core, then ->cpu
 */
int get_cpu_topology(struct cpupower_topology *cpu_top)
{
        int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF);

        cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus);
        if (cpu_top->core_info == NULL)
                return -ENOMEM;
        cpu_top->pkgs = cpu_top->cores = 0;
        for (cpu = 0; cpu < cpus; cpu++) {
                cpu_top->core_info[cpu].cpu = cpu;
                cpu_top->core_info[cpu].is_online = cpupower_is_cpu_online(cpu);
                if(sysfs_topology_read_file(
                        cpu,
                        "physical_package_id",
                        &(cpu_top->core_info[cpu].pkg)) < 0) {
                        cpu_top->core_info[cpu].pkg = -1;
                        cpu_top->core_info[cpu].core = -1;
                        continue;
                }
                if(sysfs_topology_read_file(
                        cpu,
                        "core_id",
                        &(cpu_top->core_info[cpu].core)) < 0) {
                        cpu_top->core_info[cpu].pkg = -1;
                        cpu_top->core_info[cpu].core = -1;
                        continue;
                }
        }

        qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
              __compare);

        /* Count the number of distinct pkgs values. This works
           because the primary sort of the core_info struct was just
           done by pkg value. */
        last_pkg = cpu_top->core_info[0].pkg;
        for(cpu = 1; cpu < cpus; cpu++) {
                if (cpu_top->core_info[cpu].pkg != last_pkg &&
                                cpu_top->core_info[cpu].pkg != -1) {

                        last_pkg = cpu_top->core_info[cpu].pkg;
                        cpu_top->pkgs++;
                }
        }
        if (!(cpu_top->core_info[0].pkg == -1))
                cpu_top->pkgs++;

        /* Intel's cores count is not consecutively numbered, there may
         * be a core_id of 3, but none of 2. Assume there always is 0
         * Get amount of cores by counting duplicates in a package
        for (cpu = 0; cpu_top->core_info[cpu].pkg = 0 && cpu < cpus; cpu++) {
                if (cpu_top->core_info[cpu].core == 0)
        cpu_top->cores++;
        */
        return cpus;
}

void cpu_topology_release(struct cpupower_topology cpu_top)
{
        free(cpu_top.core_info);
}