C语言读写伯克利DB 3

gcc -o channeldb channel.c -db -Wall
# -Wall参数等价于执行lint，即：进行代码的静态分析，它可以指出未初始化的变量，未使用的变量

#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <db.h>
#include <sys/types.h>
#include <getopt.h>

//define DATABASE "/work/stat/read/newstat/data/userlist/historydb/channel.db"

#define DATABASE "/mnt/disk1/ucshuqi/touch/userlist/historydb/channel.db"
#define YES 1
#define NO  0


/* ViewData Module */

struct ViewData {
        int date;
};

void setDate(struct ViewData *data,char *s)
{
        assert(data!=NULL && s!= NULL && strlen(s) == 8);
        data->date = atoi(s);
}

// the function return YES when query.date >= stored.date
int isHistoryViewInfo(struct ViewData *query , struct ViewData *stored)
{
        assert(query != NULL && stored != NULL);
        printf("query date is %d , stored date is %d 
",query->date, stored->date);

        if(query->date >= stored->date)
        {
                return YES;
        }
        else
        {
                return NO;
        }
}

void printViewData(struct ViewData *data)
{
        printf("print view date : %d
",data->date);
}


/* string helper module */

char *trim(char *s)
{
        int i = strlen(s);
        for(;i>0;i--)
        {
                if(s[i]==' ' || s[i]=='
' || s[i]=='' || s[i]=='	')
                {
                        s[i] = '';
                }
                else
                {
                        break;
                }
        }
        return s;
}

/* database helper module */

DB *openDb()
{
        int ret;
        DB *dbp = NULL;

        ret = db_create(&dbp, NULL, 0);
        if(ret != 0)
        {
                fprintf(stderr,"create Db error!
");
                exit(1);
        }

        ret = dbp->open(dbp, NULL, DATABASE, NULL, DB_BTREE, DB_CREATE,0664);

        if(ret != 0)
        {
                fprintf(stderr,"open Db error!
");
                exit(1);
        }

        return dbp;
}

/* business module */

int saveViewInfo(DB *dbp, char *user, struct ViewData *data)
{
        DBT key,value;

        memset(&key, 0, sizeof(key));
        key.data = user;
        key.size = strlen(user) + 1;

        memset(&value, 0, sizeof(value));
        value.data = data;
        value.size = sizeof(*data);
        if(dbp->put(dbp, NULL, &key, &value, 0) == 0)
        {
                //printf("save ---> %s, %d
", key.data, key.size);
                printViewData(value.data);
                return YES;
        }
        else
        {
                return NO;
        }
}

int findViewInfo(DB *dbp, char *user, struct ViewData *data)
{
        DBT key,value;

        memset(&key, 0, sizeof(key));
        key.data = user;
        key.size = strlen(user) + 1;

        memset(&value,0,sizeof(value)); // must !!!

        if(dbp->get(dbp, NULL, &key, &value, 0) == 0)
        {
                memcpy((char*)data,(char*)value.data,value.size);
                //printViewData(data);
                return YES; //view in database 
        }
        else
        {
                return NO; //view not in database
        }
}

void recordNewView(FILE *fp, char *user)                                                          
{
        char buffer[1024] = {0};                                                                
        assert(fp != NULL && user != NULL);                                                     

        printf("%s is new view
", user);
        sprintf(buffer, "%s found
", user);                                               
        fwrite(buffer, sizeof(char), strlen(buffer), fp);
}

void saveViewFile(char *from, char *to, struct ViewData *writeData)
{
        DB *dbp = openDb();
        struct ViewData stored;
        char buffer[1024 * 4];
        FILE *fp = fopen(from,"r");
        FILE *fpResult = fopen(to,"w");

        assert(fp != NULL && fpResult != NULL && writeData != NULL);

        while(fgets((char*)buffer, 1024*4, fp)!=NULL)
        {
                char *user = trim((char*)buffer);
                memset(&stored, 0, sizeof(stored));

                if(findViewInfo(dbp, user, &stored) == YES)
                {
                        if(isHistoryViewInfo(writeData,&stored) == NO)
                        {
                                recordNewView(fpResult, user);
                        }
                        continue;
                }

                recordNewView(fpResult, user);
                if(saveViewInfo(dbp, user, writeData) == NO)
                {
                        printf("save %s faild
", user);
                }
                memset(&buffer, 0, 1024 * 4); 
        }
        dbp->close(dbp, 0);
        fclose(fp);
        fclose(fpResult);
}

void hasViewInfo(char *user, struct ViewData *query)
{
        DB *dbp = NULL;
        struct ViewData stored;

        dbp = openDb();
        assert(user != NULL);
        memset(&stored, 0 ,sizeof(stored));
        user = trim(user);

        if(findViewInfo(dbp, user, &stored) == YES)
        {
                if(isHistoryViewInfo(query, &stored) == YES)
                {
                        printf("found %s
",user);
                }
                else
                {
                        //printf("%s in db
",user);
                        printf("not found %s
",user);
                }
        }
        else
        {
                printf("%s not in db
",user);
                printf("not found %s
",user);
        }

        dbp->close(dbp, 0);
}


int main (int argc, char *argv[])
{
        int oc;
        extern char *optarg;
        extern int optind, opterr, optopt;

        char *from = NULL;
        char *to = NULL;

        struct ViewData viewData;
        memset(&viewData, 0, sizeof(viewData));

        while((oc=getopt(argc,argv,"f:s:t:")) != -1)
        {
                switch(oc)
                {
                        case 's':
                                setDate(&viewData,argv[optind]);
                                hasViewInfo(optarg, &viewData);
                                break;

                        case 'f':
                                from = optarg;
                                to = argv[optind++];
                                setDate(&viewData,argv[optind]);
                                saveViewFile(from, to, &viewData);
                                break;
                }
        }

        return 0;
}

我开始把ViewData写成了这样:

struct ViewData{
    char date[12];    
};

void setDate(char *date, char *s)
{
    assert(date != NULL && s!= NULL);
    strncpy(&date,s,12);
}

//call setDate
struct ViewData viewData;
memset(viewData,0,sizeof(viewData));
setDate(&viewData.date,"20130808");

后来还是觉得viewData直接存int更好：

struct ViewData{
    int date;    
};

void setDate(int *date, char *s)
{
    assert(date != NULL && s!= NULL);
    *date = atoi(s);
}

//call setDate
struct ViewData viewData;
memset(viewData,0,sizeof(viewData));
setDate(&viewData.date,"20130808");

看似没啥问题，但其实我已经暴露了ViewData的实现！

//call setDate
struct ViewData viewData;
memset(viewData,0,sizeof(viewData));
setDate(&viewData.date,"20130808");
//断言设置之后的日期等于20130808,用户这么写是因为已经暴露了ViewData的date是字符串这个事情！
assert(strcmp(viewData.date,"20130808")==0); 

那你说，不怎么写我想知道是不是设置成功了怎么办？

//call setDate
struct ViewData viewData;
memset(viewData,0,sizeof(viewData));
setDate(&viewData.date,"20130808");
//断言设置之后的日期等于20130808,这个函数由ViewData模块提供
verifyDate(&viewDate,"20130808");