/*
 * BSD LICENSE
 *
 * Copyright(c) 2018-2023 Intel Corporation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *   * Neither the name of Intel Corporation nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "resctrl.h"

#include "common.h"
#include "log.h"
#include "os_common.h"

#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>
#include <sys/mount.h>
#include <unistd.h>

static int resctrl_lock_fd = -1; /**< File descriptor to the lockfile */

/**
 * @brief Handle SIGALRM
 */
static void
resctrl_lock_signalhandler(int signal)
{
        UNUSED_PARAM(signal);
        /* File lock timeout */
}

/**
 * @brief Obtain lock on resctrl filesystem
 *
 * @param[in] type lock type
 *
 * @return Operational status
 * @retval PQOS_RETVAL_OK on success
 */
static int
resctrl_lock(const int type)
{
        struct sigaction sa;
        int ret = PQOS_RETVAL_ERROR;

        ASSERT(type == LOCK_SH || type == LOCK_EX);

        resctrl_lock_fd = open(RESCTRL_PATH, O_DIRECTORY);
        if (resctrl_lock_fd < 0) {
                LOG_ERROR("Could not open %s directory\n", RESCTRL_PATH);
                return PQOS_RETVAL_ERROR;
        }

        /* Handle SIGALRM */
        sigaction(SIGALRM, NULL, &sa);
        sa.sa_handler = resctrl_lock_signalhandler;
        sa.sa_flags = 0;
        sigaction(SIGALRM, &sa, NULL);

        /* Set alarm when 100ms timeout occurs */
        ualarm(100000, 0);

        if (flock(resctrl_lock_fd, type) == 0) {
                ret = PQOS_RETVAL_OK;
                goto resctrl_lock_exit;
        }

        if (errno == EINTR)
                LOG_ERROR("Failed to acquire lock on resctrl filesystem - "
                          "timeout occurred\n");
        else
                LOG_ERROR("Failed to acquire lock on resctrl filesystem - "
                          "%m\n");

        close(resctrl_lock_fd);
        resctrl_lock_fd = -1;

resctrl_lock_exit:
        /* disable alarm */
        ualarm(0, 0);
        sa.sa_handler = SIG_DFL;

        return ret;
}

int
resctrl_lock_shared(void)
{
        return resctrl_lock(LOCK_SH);
}

int
resctrl_lock_exclusive(void)
{
        return resctrl_lock(LOCK_EX);
}

int
resctrl_lock_release(void)
{
        if (resctrl_lock_fd < 0) {
                LOG_ERROR("Resctrl filesystem not locked\n");
                return PQOS_RETVAL_ERROR;
        }

        if (flock(resctrl_lock_fd, LOCK_UN) != 0)
                LOG_WARN("Failed to release lock on resctrl filesystem\n");

        close(resctrl_lock_fd);
        resctrl_lock_fd = -1;

        return PQOS_RETVAL_OK;
}

int
resctrl_mount(const enum pqos_cdp_config l3_cdp_cfg,
              const enum pqos_cdp_config l2_cdp_cfg,
              const enum pqos_mba_config mba_cfg)
{
        const char *options = NULL;
        char buf[32] = "";

        ASSERT(l3_cdp_cfg == PQOS_REQUIRE_CDP_ON ||
               l3_cdp_cfg == PQOS_REQUIRE_CDP_OFF);
        ASSERT(l2_cdp_cfg == PQOS_REQUIRE_CDP_ON ||
               l2_cdp_cfg == PQOS_REQUIRE_CDP_OFF);
        ASSERT(mba_cfg == PQOS_MBA_DEFAULT || mba_cfg == PQOS_MBA_CTRL);

        /* l3 cdp mount option */
        if (l3_cdp_cfg == PQOS_REQUIRE_CDP_ON) {
                pqos_strcat(buf, "cdp", sizeof(buf));
                options = buf;
        }

        /* l2 cdp mount option */
        if (l2_cdp_cfg == PQOS_REQUIRE_CDP_ON) {
                if (options != NULL)
                        pqos_strcat(buf, ",", sizeof(buf));
                pqos_strcat(buf, "cdpl2", sizeof(buf));
                options = buf;
        }

        /* mba mount option */
        if (mba_cfg == PQOS_MBA_CTRL) {
                if (options != NULL)
                        pqos_strcat(buf, ",", sizeof(buf));
                pqos_strcat(buf, "mba_MBps", sizeof(buf));
                options = buf;
        }

        if (mount("resctrl", RESCTRL_PATH, "resctrl", 0, options) != 0) {
                LOG_DEBUG("resctrl mount failed with error %d - %m\n", errno);
                return PQOS_RETVAL_ERROR;
        }

        return PQOS_RETVAL_OK;
}

int
resctrl_umount(void)
{
        if (umount2(RESCTRL_PATH, 0) != 0) {
                LOG_ERROR("Could not umount resctrl filesystem!\n");
                return PQOS_RETVAL_ERROR;
        }

        return PQOS_RETVAL_OK;
}

/*
 * ---------------------------------------
 * CPU mask structures and utility functions
 * ---------------------------------------
 */

void
resctrl_cpumask_set(const unsigned lcore, struct resctrl_cpumask *mask)
{
        /* index in mask table */
        const unsigned item = (sizeof(mask->tab) - 1) - (lcore / CHAR_BIT);
        const unsigned bit = lcore % CHAR_BIT;

        /* Set lcore bit in mask table item */
        mask->tab[item] = mask->tab[item] | (1 << bit);
}

void
resctrl_cpumask_unset(const unsigned lcore, struct resctrl_cpumask *mask)
{
        /* index in mask table */
        const unsigned item = (sizeof(mask->tab) - 1) - (lcore / CHAR_BIT);
        const unsigned bit = lcore % CHAR_BIT;

        /* Clear lcore bit in mask table item */
        mask->tab[item] &= ~(1 << bit);
}

int
resctrl_cpumask_get(const unsigned lcore, const struct resctrl_cpumask *mask)
{
        /* index in mask table */
        const unsigned item = (sizeof(mask->tab) - 1) - (lcore / CHAR_BIT);
        const unsigned bit = lcore % CHAR_BIT;

        /* Check if lcore bit is set in mask table item */
        return (mask->tab[item] >> bit) & 0x1;
}

int
resctrl_cpumask_write(FILE *fd, const struct resctrl_cpumask *mask)
{
        unsigned i;
        unsigned found_nonzero = 0;

        ASSERT(fd != NULL);
        ASSERT(mask != NULL);

        for (i = 0; i < sizeof(mask->tab); i++) {
                const unsigned value = (unsigned)mask->tab[i];

                /* skip leading 0 */
                if (!found_nonzero && value == 0x0)
                        continue;
                found_nonzero = 1;

                if (fprintf(fd, "%02x", value) < 0) {
                        LOG_ERROR("Failed to write cpu mask\n");
                        break;
                }
                if ((i + 1) % 4 == 0)
                        if (fprintf(fd, ",") < 0) {
                                LOG_ERROR("Failed to write cpu mask\n");
                                break;
                        }
        }
        if (!found_nonzero)
                fprintf(fd, "0");

        /* check if error occurred in loop */
        if (i < sizeof(mask->tab))
                return PQOS_RETVAL_ERROR;

        return PQOS_RETVAL_OK;
}

int
resctrl_cpumask_read(FILE *fd, struct resctrl_cpumask *mask)
{
        int i, hex_offset, idx;
        size_t num_chars = 0;
        char cpus[RESCTRL_MAX_CPUS / CHAR_BIT];

        ASSERT(fd != NULL);
        ASSERT(mask != NULL);

        memset(mask, 0, sizeof(struct resctrl_cpumask));
        memset(cpus, 0, sizeof(cpus));

        /** Read the entire file into memory. */
        num_chars = fread(cpus, sizeof(char), sizeof(cpus), fd);

        if (ferror(fd) != 0) {
                LOG_ERROR("Error reading CPU file\n");
                return PQOS_RETVAL_ERROR;
        }
        cpus[sizeof(cpus) - 1] = '\0'; /** Just to be safe. */

        /**
         *  Convert the cpus array into hex, skip any non hex chars.
         *  Store the hex values in the mask tab.
         */
        for (i = num_chars - 1, hex_offset = 0, idx = sizeof(mask->tab) - 1;
             i >= 0; i--) {
                const char c = cpus[i];
                int hex_num;

                if ('0' <= c && c <= '9')
                        hex_num = c - '0';
                else if ('a' <= c && c <= 'f')
                        hex_num = 10 + c - 'a';
                else if ('A' <= c && c <= 'F')
                        hex_num = 10 + c - 'A';
                else
                        continue;

                if (!hex_offset)
                        mask->tab[idx] = (uint8_t)hex_num;
                else {
                        mask->tab[idx] |= (uint8_t)(hex_num << 4);
                        idx--;
                }
                hex_offset ^= 1;
        }

        return PQOS_RETVAL_OK;
}

int
resctrl_is_supported(void)
{
        int ret;
        int resctrl = 0;

        ret = pqos_file_contains(PROC_FILESYSTEMS, "resctrl", &resctrl);
        if (ret != PQOS_RETVAL_OK) {
                /* The log message below may not appear if log module
                   is not initialized */
                LOG_ERROR("Fatal error encountered in resctrl detection!\n");
                return ret;
        }
        /* The log message below may not appear if log module
           is not initialized */
        LOG_INFO("%s\n", resctrl ? "resctrl detected"
                                 : "resctrl not detected. "
                                   "Kernel version 4.10 or higher required");

        if (resctrl == 0)
                return PQOS_RETVAL_RESOURCE;

        return PQOS_RETVAL_OK;
}