/*
 * Copyright (c) 2016, Salvatore Sanfilippo <antirez at gmail dot com>
 * 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 Redis 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 "server.h"
#include "rdb.h"

#include <stdarg.h>

void rdbLoadProgressCallback(rio *r, const void *buf, size_t len);
long long rdbLoadMillisecondTime(rio *rdb);

struct {
    rio *rio;
    robj *key;                      /* Current key we are reading. */
    unsigned long keys;             /* Number of keys processed. */
    unsigned long expires;          /* Number of keys with an expire. */
    unsigned long already_expired;  /* Number of keys already expired. */
    int doing;                      /* The state while reading the RDB. */
} rdbstate;

#define RDB_CHECK_DOING_START 0
#define RDB_CHECK_DOING_READ_EXPIRE 1
#define RDB_CHECK_DOING_READ_KEY 2
#define RDB_CHECK_DOING_READ_VALUE 3

/* Called on RDB errors. Provides details about the RDB and the offset
 * we were when the error was detected. */
void rdbCheckError(const char *fmt, ...) {
    char msg[1024];
    va_list ap;

    va_start(ap, fmt);
    vsnprintf(msg, sizeof(msg), fmt, ap);
    va_end(ap);

    printf("*** RDB CHECK FAILED: %s ***\n", msg);
    printf("AT RDB OFFSET: %llu\n",
        (unsigned long long) (rdbstate.rio ?
            rdbstate.rio->processed_bytes : 0));
    if (rdbstate.key)
        printf("READING KEY: %s\n", (char*)rdbstate.key->ptr);
}

/* Print informations during RDB checking. */
void rdbCheckInfo(const char *fmt, ...) {
    char msg[1024];
    va_list ap;

    va_start(ap, fmt);
    vsnprintf(msg, sizeof(msg), fmt, ap);
    va_end(ap);

    printf("[offset %llu] %s\n",
        (unsigned long long) (rdbstate.rio ?
            rdbstate.rio->processed_bytes : 0), msg);
}

/* During RDB check we setup a special signal handler for memory violations
 * and similar conditions, so that we can log the offending part of the RDB
 * if the crash is due to broken content. */
void rdbCheckHandleCrash(int sig, siginfo_t *info, void *secret) {
    UNUSED(sig);
    UNUSED(info);
    UNUSED(secret);

    rdbCheckError("Server crash checking the specified RDB file!");
    exit(1);
}

void rdbCheckSetupSignals(void) {
    struct sigaction act;

    sigemptyset(&act.sa_mask);
    act.sa_flags = SA_NODEFER | SA_RESETHAND | SA_SIGINFO;
#warning "Uncomment here"
//    act.sa_sigaction = rdbCheckHandleCrash;
    sigaction(SIGSEGV, &act, NULL);
    sigaction(SIGBUS, &act, NULL);
    sigaction(SIGFPE, &act, NULL);
    sigaction(SIGILL, &act, NULL);
}

/* Check the specified RDB file. */
int redis_check_rdb(char *rdbfilename) {
    uint64_t dbid;
    int type, rdbver;
    char buf[1024];
    long long expiretime, now = mstime();
    FILE *fp;
    rio rdb;

    if ((fp = fopen(rdbfilename,"r")) == NULL) return C_ERR;

    rioInitWithFile(&rdb,fp);
    rdbstate.rio = &rdb;
    rdb.update_cksum = rdbLoadProgressCallback;
    if (rioRead(&rdb,buf,9) == 0) goto eoferr;
    buf[9] = '\0';
    if (memcmp(buf,"REDIS",5) != 0) {
        rdbCheckError("Wrong signature trying to load DB from file");
        return 1;
    }
    rdbver = atoi(buf+5);
    if (rdbver < 1 || rdbver > RDB_VERSION) {
        rdbCheckError("Can't handle RDB format version %d",rdbver);
        return 1;
    }

    startLoading(fp);
    while(1) {
        robj *key, *val;
        expiretime = -1;

        /* Read type. */
        if ((type = rdbLoadType(&rdb)) == -1) goto eoferr;

        /* Handle special types. */
        if (type == RDB_OPCODE_EXPIRETIME) {
            /* EXPIRETIME: load an expire associated with the next key
             * to load. Note that after loading an expire we need to
             * load the actual type, and continue. */
            if ((expiretime = rdbLoadTime(&rdb)) == -1) goto eoferr;
            /* We read the time so we need to read the object type again. */
            if ((type = rdbLoadType(&rdb)) == -1) goto eoferr;
            /* the EXPIRETIME opcode specifies time in seconds, so convert
             * into milliseconds. */
            expiretime *= 1000;
        } else if (type == RDB_OPCODE_EXPIRETIME_MS) {
            /* EXPIRETIME_MS: milliseconds precision expire times introduced
             * with RDB v3. Like EXPIRETIME but no with more precision. */
            if ((expiretime = rdbLoadMillisecondTime(&rdb)) == -1) goto eoferr;
            /* We read the time so we need to read the object type again. */
            if ((type = rdbLoadType(&rdb)) == -1) goto eoferr;
        } else if (type == RDB_OPCODE_EOF) {
            /* EOF: End of file, exit the main loop. */
            break;
        } else if (type == RDB_OPCODE_SELECTDB) {
            /* SELECTDB: Select the specified database. */
            if ((dbid = rdbLoadLen(&rdb,NULL)) == RDB_LENERR)
                goto eoferr;
            rdbCheckInfo("Selecting DB ID %d", dbid);
            continue; /* Read type again. */
        } else if (type == RDB_OPCODE_RESIZEDB) {
            /* RESIZEDB: Hint about the size of the keys in the currently
             * selected data base, in order to avoid useless rehashing. */
            uint64_t db_size, expires_size;
            if ((db_size = rdbLoadLen(&rdb,NULL)) == RDB_LENERR)
                goto eoferr;
            if ((expires_size = rdbLoadLen(&rdb,NULL)) == RDB_LENERR)
                goto eoferr;
            continue; /* Read type again. */
        } else if (type == RDB_OPCODE_AUX) {
            /* AUX: generic string-string fields. Use to add state to RDB
             * which is backward compatible. Implementations of RDB loading
             * are requierd to skip AUX fields they don't understand.
             *
             * An AUX field is composed of two strings: key and value. */
            robj *auxkey, *auxval;
            if ((auxkey = rdbLoadStringObject(&rdb)) == NULL) goto eoferr;
            if ((auxval = rdbLoadStringObject(&rdb)) == NULL) goto eoferr;

            rdbCheckInfo("%s = '%s'", (char*)auxkey->ptr, (char*)auxval->ptr);
            decrRefCount(auxkey);
            decrRefCount(auxval);
            continue; /* Read type again. */
        }

        /* Read key */
        if ((key = rdbLoadStringObject(&rdb)) == NULL) goto eoferr;
        rdbstate.key = key;
        rdbstate.keys++;
        /* Read value */
        if ((val = rdbLoadObject(type,&rdb)) == NULL) goto eoferr;
        /* Check if the key already expired. This function is used when loading
         * an RDB file from disk, either at startup, or when an RDB was
         * received from the master. In the latter case, the master is
         * responsible for key expiry. If we would expire keys here, the
         * snapshot taken by the master may not be reflected on the slave. */
        if (server.masterhost == NULL && expiretime != -1 && expiretime < now)
            rdbstate.already_expired++;
        if (expiretime != -1) rdbstate.expires++;
        rdbstate.key = NULL;
        decrRefCount(key);
        decrRefCount(val);
    }
    /* Verify the checksum if RDB version is >= 5 */
    if (rdbver >= 5 && server.rdb_checksum) {
        uint64_t cksum, expected = rdb.cksum;

        if (rioRead(&rdb,&cksum,8) == 0) goto eoferr;
        memrev64ifbe(&cksum);
        if (cksum == 0) {
            rdbCheckInfo("RDB file was saved with checksum disabled: no check performed.");
        } else if (cksum != expected) {
            rdbCheckError("RDB CRC error");
        }
    }

    fclose(fp);
    return 0;

eoferr: /* unexpected end of file is handled here with a fatal exit */
    rdbCheckError("Unexpected EOF reading RDB file");
    return 1;
}

/* RDB check main: called form redis.c when Redis is executed with the
 * redis-check-rdb alias.
 *
 * The function never returns, but exits with the status code according
 * to success (RDB is sane) or error (RDB is corrupted). */
int redis_check_rdb_main(char **argv, int argc) {
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <rdb-file-name>\n", argv[0]);
        exit(1);
    }
    createSharedObjects(); /* Needed for loading. */
    server.loading_process_events_interval_bytes = 0;
    rdbCheckInfo("Checking RDB file %s", argv[1]);
    rdbCheckSetupSignals();
    int retval = redis_check_rdb(argv[1]);
    if (retval == 0) {
        rdbCheckInfo("\\o/ RDB looks OK! \\o/");
    }
    exit(retval);
}