/*
 * Copyright 2022-2026 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdint.h>
#include <openssl/crypto.h>
#include "internal/cryptlib.h"

#define OPENSSL_RISCVCAP_IMPL
#include "crypto/riscv_arch.h"

#ifdef OSSL_RISCV_HWPROBE
#include <unistd.h>
#include <sys/syscall.h>
#include <asm/hwprobe.h>
#endif

extern size_t riscv_vlen_asm(void);

static size_t vlen = 0;

uint32_t OPENSSL_rdtsc(void)
{
    return 0;
}

size_t OPENSSL_instrument_bus(unsigned int *out, size_t cnt)
{
    return 0;
}

size_t OPENSSL_instrument_bus2(unsigned int *out, size_t cnt, size_t max)
{
    return 0;
}

static void strtoupper(const char *str, char *dst, size_t dstlen)
{
    for (size_t i = 0; i < dstlen; i++) {
        if (i == dstlen - 1 || str[i] == '\0') {
            dst[i] = '\0';
            break;
        }
        dst[i] = toupper((unsigned char)str[i]);
    }
}

/* parse_env() parses a RISC-V architecture string. An example of such a string
 * is "rv64gc_zba_zbb_zbc_zbs". Currently, the rv64gc part is ignored
 * and we simply search for "_[extension]" in the arch string to see if we
 * should enable a given extension.
 */
#define BUFLEN 256
static void parse_env(const char *envstr)
{
    char envstrupper[BUFLEN];
    char buf[BUFLEN];

    /* Convert env str to all uppercase */
    strtoupper(envstr, envstrupper, sizeof(envstrupper));

    for (size_t i = 0; i < kRISCVNumCaps; ++i) {
        size_t len = strlen(RISCV_capabilities[i].name);
        /* Prefix capability with underscore in preparation for search */
        /*
         * Avoid using higher level library functions which may require
         * library initialization (such as BIO_snprintf) as this may be called
         * in a constructor before library initialization
         */
        if (len < BUFLEN - 1) {
            buf[0] = '_';
            memcpy(buf + 1, RISCV_capabilities[i].name, len);
            buf[len + 1] = '\0';
            if (strstr(envstrupper, buf) != NULL) {
                /* Match, set relevant bit in OPENSSL_riscvcap_P[] */
                OPENSSL_riscvcap_P[RISCV_capabilities[i].index] |= (1 << RISCV_capabilities[i].bit_offset);
            }
        }
    }
}

#ifdef OSSL_RISCV_HWPROBE
static long riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
    size_t cpu_count, unsigned long *cpus,
    unsigned int flags)
{
    return syscall(__NR_riscv_hwprobe, pairs, pair_count, cpu_count, cpus, flags);
}

static void hwprobe_to_cap(void)
{
    long ret;
    struct riscv_hwprobe pairs[OSSL_RISCV_HWPROBE_PAIR_COUNT] = {
        OSSL_RISCV_HWPROBE_PAIR_CONTENT
    };

    ret = riscv_hwprobe(pairs, OSSL_RISCV_HWPROBE_PAIR_COUNT, 0, NULL, 0);
    /* if hwprobe syscall does not exist, ret would be -ENOSYS */
    if (ret == 0) {
        for (size_t i = 0; i < kRISCVNumCaps; ++i) {
            for (size_t j = 0; j != OSSL_RISCV_HWPROBE_PAIR_COUNT; ++j) {
                if (pairs[j].key == RISCV_capabilities[i].hwprobe_key
                    && (pairs[j].value & RISCV_capabilities[i].hwprobe_value)
                        != 0)
                    /* Match, set relevant bit in OPENSSL_riscvcap_P[] */
                    OPENSSL_riscvcap_P[RISCV_capabilities[i].index] |= (1 << RISCV_capabilities[i].bit_offset);
            }
        }
    }
}
#endif /* OSSL_RISCV_HWPROBE */

size_t riscv_vlen(void)
{
    return vlen;
}

#if defined(__GNUC__) && __GNUC__ >= 2
__attribute__((constructor))
#endif
void OPENSSL_cpuid_setup(void)
{
    char *e;
    static int trigger = 0;

    if (trigger != 0)
        return;
    trigger = 1;

    if ((e = getenv("OPENSSL_riscvcap"))) {
        parse_env(e);
    }
#ifdef OSSL_RISCV_HWPROBE
    else {
        hwprobe_to_cap();
    }
#endif

    if (RISCV_HAS_V()) {
        vlen = riscv_vlen_asm();
    }
}
