redis源码（八）redis-check-aof.c

/*
 * Copyright (c) 2009-2012, Pieter Noordhuis <pcnoordhuis at gmail dot com>
 * Copyright (c) 2009-2012, 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 "fmacros.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include "config.h"

#define ERROR(...) { \
    char __buf[]; \
    sprintf(__buf, __VA_ARGS__); \
    sprintf(error, "0x%16llx: %s", (long long)epos, __buf); \
}

static char error[];
static off_t epos;

int consumeNewline(char *buf) {
    if (strncmp(buf,"\r\n",) != ) {
        ERROR("Expected \\r\\n, got: %02x%02x",buf[],buf[]);
        return ;
    }
    return ;
}

int readLong(FILE *fp, char prefix, long *target) {
    char buf[], *eptr;
    epos = ftello(fp);
    if (fgets(buf,sizeof(buf),fp) == NULL) {
        return ;
    }
    if (buf[] != prefix) {
        ERROR("Expected prefix '%c', got: '%c'",buf[],prefix);
        return ;
    }
    *target = strtol(buf+,&eptr,);
    return consumeNewline(eptr);
}

int readBytes(FILE *fp, char *target, long length) {
    long real;
    epos = ftello(fp);
    real = fread(target,,length,fp);
    if (real != length) {
        ERROR("Expected to read %ld bytes, got %ld bytes",length,real);
        return ;
    }
    return ;
}

int readString(FILE *fp, char** target) {
    long len;
    *target = NULL;
    if (!readLong(fp,'$',&len)) {
        return ;
    }

    /* Increase length to also consume \r\n */
    len += ;
    *target = (char*)malloc(len);
    if (!readBytes(fp,*target,len)) {
        return ;
    }
    if (!consumeNewline(*target+len-)) {
        return ;
    }
    (*target)[len-] = '\0';
    return ;
}

int readArgc(FILE *fp, long *target) {
    return readLong(fp,'*',target);
}

off_t process(FILE *fp) {
    long argc;
    off_t pos = ;
    int i, multi = ;
    char *str;

    while() {
        if (!multi) pos = ftello(fp);
        if (!readArgc(fp, &argc)) break;

        for (i = ; i < argc; i++) {
            if (!readString(fp,&str)) break;
            if (i == ) {
                if (strcasecmp(str, "multi") == ) {
                    if (multi++) {
                        ERROR("Unexpected MULTI");
                        break;
                    }
                } else if (strcasecmp(str, "exec") == ) {
                    if (--multi) {
                        ERROR("Unexpected EXEC");
                        break;
                    }
                }
            }
            free(str);
        }

        /* Stop if the loop did not finish */
        if (i < argc) {
            if (str) free(str);
            break;
        }
    }

    if (feof(fp) && multi && strlen(error) == ) {
        ERROR("Reached EOF before reading EXEC for MULTI");
    }
    if (strlen(error) > ) {
        printf("%s\n", error);
    }
    return pos;
}

int main(int argc, char **argv) {
    char *filename;
    int fix = ;

    if (argc < ) {
        printf("Usage: %s [--fix] <file.aof>\n", argv[]);
        exit();
    } else if (argc == ) {
        filename = argv[];
    } else if (argc == ) {
        if (strcmp(argv[],"--fix") != ) {
            printf("Invalid argument: %s\n", argv[]);
            exit();
        }
        filename = argv[];
        fix = ;
    } else {
        printf("Invalid arguments\n");
        exit();
    }

    FILE *fp = fopen(filename,"r+");
    if (fp == NULL) {
        printf("Cannot open file: %s\n", filename);
        exit();
    }

    struct redis_stat sb;
    if (redis_fstat(fileno(fp),&sb) == -) {
        printf("Cannot stat file: %s\n", filename);
        exit();
    }

    off_t size = sb.st_size;
    if (size == ) {
        printf("Empty file: %s\n", filename);
        exit();
    }

    off_t pos = process(fp);
    off_t diff = size-pos;
    printf("AOF analyzed: size=%lld, ok_up_to=%lld, diff=%lld\n",
        (long long) size, (long long) pos, (long long) diff);
    if (diff > ) {
        if (fix) {
            char buf[];
            printf("This will shrink the AOF from %lld bytes, with %lld bytes, to %lld bytes\n",(long long)size,(long long)diff,(long long)pos);
            printf("Continue? [y/N]: ");
            if (fgets(buf,sizeof(buf),stdin) == NULL ||
                strncasecmp(buf,"y",) != ) {
                    printf("Aborting...\n");
                    exit();
            }
            if (ftruncate(fileno(fp), pos) == -) {
                printf("Failed to truncate AOF\n");
                exit();
            } else {
                printf("Successfully truncated AOF\n");
            }
        } else {
            printf("AOF is not valid\n");
            exit();
        }
    } else {
        printf("AOF is valid\n");
    }

    fclose(fp);
    return ;
}

1、如何使用？这里有什么意义，为什么需要这样使用？