openwrt中自定义配置文件解析

在Linux/openwrt等嵌入式系统中，使用到了大量配置文件，比如硬件配置，系统配置，应用程序

配置。这些配置信息通常都是以文本文件为载体，以键值对的形式存储于本地或远程文件系统中。

可以参考openwrt的uci命令系统，简易的自定义自己程序的配置文件解析，方便于在命令行或

应用程序内部即时读写配置参数。

 config_file_rw.c

/**
create by iversondeng168 
*/
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 


#define DEBUG

#define CONFIG_FILE      "./etc/config_file_rw.conf"



//键值对结构体
typedef struct item_t {
    char *key;
    char *value;
}ITEM;



//去除一行字符串右边的空格
char *str_trim_right(char *pstr)
{
    int i;
    i = strlen(pstr) - 1;
    
    while (isspace(pstr[i]) && i >= 0)
        pstr[i--] = 0;
        
    return pstr;
}


//去除一行字符串左边的空格
char *str_trim_left(char *pstr)
{
    int i = 0,j = 0;
    j = strlen(pstr) - 1;
    
    while (isspace(pstr[i]) && (i <= j))
        i++;
        
    if (0 < i)
        strcpy(pstr, &pstr[i]);
        
    return pstr;
}


//同时去除字符串左右两边的空格
char *str_trim(char *pstr)
{
    char *p;
    
    p = str_trim_right(pstr);
    
    return str_trim_left(p);
}



//从一行字符串中解析出键值对
int  get_item_from_line(char *line, ITEM *item)
{
    char *pline = str_trim(line);
    int len     = strlen(pline);
    
    if(len <= 0)
    {
        return -1;
    }
    else if(pline[0]=='#' || pline[0]=='/')
    {
        return -2;
    }
    else
    {
        char *p = strchr(pline, '=');
        *p++ = 0;
        
        item->key   = (char *)malloc(strlen(pline) + 1);
        item->value = (char *)malloc(strlen(p) + 1);
        
        pline = str_trim(pline);
        p     = str_trim(p);
        
        strcpy(item->key,pline);
        strcpy(item->value,p);

    }
    
    return 0;
}



//将整个配置文件解析出键值对数组保存在内存中
int file_to_items(const char *filename, ITEM *items, int *num)
{
    char line[1024];
    FILE *fp;
    
    fp = fopen(filename,"r");
    if(fp == NULL)
        return 1;
        
    int i   = 0;
    int len = 0;
    
    char*p1 = NULL;
    char*p2 = NULL;
    
    while(fgets(line, 1024 - 1, fp))
    {
        p1  = str_trim(line);
        len = strlen(p1);
        
        if(len <= 0)
        {
            continue;
        }
        else if(p1[0]=='#')
        {
            continue;
        }
        else
        {
            p2 = strchr(p1, '=');
            
            if(p2 == NULL)
                continue;
                
            *p2++ = 0;
            
            items[i].key = (char *)malloc(strlen(p1) + 1);
            items[i].value = (char *)malloc(strlen(p2) + 1);
            
            
            p1 = str_trim(p1);
            p2 = str_trim(p2);
            
            strcpy(items[i].key,p1);
            strcpy(items[i].value,p2);

            i++;
        }
    }
    
    
    *num = i;
    fclose(fp);
    
    return 0;
}



//从配置文件中读取指定键的值
int read_conf_value(const char *filename,char *key,char *value)
{
    char line[1024];
    FILE *fp;
    ITEM item;
    
    fp = fopen(filename,"r");
    
    if(fp == NULL)
        return -1;
        
    while (fgets(line, 1024-1, fp))
    {
        
        if(get_item_from_line(line,&item))
        {
           continue;
        }

        if(!strcmp(item.key,key))
        {
            strcpy(value,item.value);

            free(item.key);
            free(item.value);

            fclose(fp);
            			
            return 0;
        }

    }
    
    fclose(fp);
	
    return -2;

}



//向配置文件中写入指定键的值
int write_conf_value(const char *filename,char *key,char *value)
{
    ITEM items[1024];
    int num;
    
    //将文件的键值对加载到内存
    file_to_items(filename, items, &num);

    int i=0;

    //修改指定键值
    for(i=0;i= num)
    {
       return -1;
    }
   
    //同步到文件 
    FILE *fp;
    fp = fopen(filename, "w");
    if(fp == NULL)
    {
       return -2;       
    }
        
        
    for(i=0;i

测试配置文件./etc/config_file_rw.conf

A1=one
B2=two
C3=three

执行交叉编译

/home/source/prebuilt/gcc/linux-x86/arm/toolchain-sunxi-musl/toolchain/bin/arm-openwrt-linux-gcc config_file_rw.c -o config_file_rw -O2 -w