为了完成读取系统中的配置文件的某个key键的值，由于使用别人的库总是不爽，而且对于格式有一定的要求，那么就自己来写一个这样的接口以供使用了。实现原理很简单，通过打开配置文件，进行一行一行的读取，对比行中是否存在key串且此key串的下一个字符是否为'=',若是，则得到'='号之后的值。
注意：此实现方法只适用于key=value这样的配置格式，而不是很多配置文件的key="value"的格式。
以下即是此接口的实现及测试代码：
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int get_conf_value(char *file_path, char *key_name, char *value)
{
FILE *fp = NULL;
char *line = NULL, *substr = NULL;
size_t len = 0, tlen = 0;
ssize_t read = 0;
if(file_path == NULL || key_name == NULL || value == NULL)
{
printf("paramer is invaild!\n");
return -1;
}
fp = fopen(file_path, "r");
if (fp == NULL)
{
printf("open config file is error!\n");
return -1;
}
while ((read = getline(&line, &len, fp)) != -1)
{
substr = strstr(line, key_name);
if(substr == NULL)
{
continue;
}
else
{
tlen = strlen(key_name);
if(line[tlen] == '=')
{
strncpy(value, &line[tlen+1], len-tlen+1);
printf("config file format is invaild tlen is %d len is %d\n", tlen, len);
tlen = strlen(value);
printf("get value is %s tlen is %d\n", value, tlen);
//replace enter key
*(value+tlen-1) = '\0';
break;
}
else
{
printf("config file format is invaild tlen is %d len is %d\n", tlen, len);
fclose(fp);
return -2;
}
}
}
if(substr == NULL)
{
printf("key: %s is not in config file!\n", key_name);
fclose(fp);
return -1;
}
free(line);
fclose(fp);
return 0;
}
int main()
{
char getva[128] = {0};
char pathname_key[] = "Path";
char profilename[] = "/home/linuxidc/.mozilla/firefox/profiles.ini";
int ret = get_conf_value(profilename, pathname_key, getva);
if(ret == 0)
printf("get pathname_key's value from profile:%s is %s\n", profilename, getva);
return ret;
}
其中profilename是firefox的配置文件，获取key：Path的值。运行结果如下：
linuxidc@linuxidc:~/$ ./a.out
config file format is invaild tlen is 4 len is 120
get value is cojs83dh.default
tlen is 17
get pathname_key's value from profile:/home/linuxidc/.mozilla/firefox/profiles.ini is cojs83dh.default
配置文件的内容如下：
linuxidc@linuxidc:~$ cat /home/linuxidc/.mozilla/firefox/profiles.ini
[General]
StartWithLastProfile=1
[Profile0]
Name=default
IsRelative=1
Path=cojs83dh.default
Default=1
405
/*********************************************************************
* Author : Samson
* Date : 03/13/2015
* Test platform:
* 3.13.0-24-generic
* GNU bash, 4.3.11(1)-release
* *******************************************************************/