A simple method of writing log files in pure C language, just compiled by gcc

overview

• This should be a log module that did not write files in the previous C language module. In order not to change the original module compilation method, I added a simple method of writing log files.
• Support windows and linux, support x86 and ARM.

full code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#ifdef WIN32
#include <windows.h>
#else
#include <unistd.h>		// linux下头文件
#endif
 
#define FILE_MAX_SIZE (1024*1024)
 
/*
获得当前时间字符串
@param buffer [out]: 时间字符串
@return 空
*/
void get_local_time(char* buffer)
{
    
    
	time_t rawtime; 
	struct tm* timeinfo;
 
	time(&rawtime); 
	timeinfo = localtime(&rawtime); 
	sprintf(buffer, "%04d-%02d-%02d %02d:%02d:%02d", 
		(timeinfo->tm_year+1900), timeinfo->tm_mon, timeinfo->tm_mday,
		timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec);
}
 
/*
获得文件大小
@param filename [in]: 文件名
@return 文件大小
*/
long get_file_size(char* filename)
{
    
    
	long length = 0;
	FILE *fp = NULL;
 
	fp = fopen(filename, "rb");
	if (fp != NULL)
	{
    
    
		fseek(fp, 0, SEEK_END);
		length = ftell(fp);
	}
 
	if (fp != NULL)
	{
    
    
		fclose(fp);
		fp = NULL;
	}
 
	return length;
}
 
/*
写入日志文件
@param filename [in]: 日志文件名
@param max_size [in]: 日志文件大小限制
@param buffer [in]: 日志内容
@param buf_size [in]: 日志内容大小
@return 空
*/
void write_log_file(char* filename, long max_size, char* buffer, unsigned buf_size)
{
    
    
	if (filename != NULL && buffer != NULL)
	{
    
    
		// 文件超过最大限制, 删除
		long length = get_file_size(filename);
 
		if (length > max_size)
		{
    
    
			unlink(filename); // 删除文件
		}
 
		// 写日志
		{
    
    
			FILE *fp;
			fp = fopen(filename, "at+");
			if (fp != NULL)
			{
    
    
				char now[32];
				memset(now, 0, sizeof(now));
				get_local_time(now);
				fwrite(now, strlen(now)+1, 1, fp);
				fwrite(buffer, buf_size, 1, fp);
 
				fclose(fp);
				fp = NULL;
			}
		}
	}
}

test code

int main(int argc, char** argv)
{
    
    
	int i;
	for (i=0; i<10; ++i)
	{
    
    
		char buffer[32];
		memset(buffer, 0, sizeof(buffer));
		sprintf(buffer, "====> %d\n", i);
		write_log_file("log.txt", FILE_MAX_SIZE, buffer, strlen(buffer));
#ifdef WIN32
		Sleep(100); // 毫秒
#else
		sleep(1);	// 秒
#endif
		
	}
	// system("pause");
	return 0;
}