curl断点续载

curl断点续传，下载过程中关闭控制台，然后重新启动，又会接着下载

#include "stdafx.h"
#include <io.h>
#include "curl/curl.h"
#include <string>/*注意包含这个头文件后必须把share.h重命名一下，可能是stl里面也有这个头文件，比如curl_share.h,然后把包含到的地方替换一下*/

#include "curl/easy.h"

using namespace std;

static size_t downLoadPackage(void *ptr, size_t size, size_t nmemb, void *userdata)
{
	FILE *fp = (FILE*)userdata;
	size_t written = fwrite(ptr, size, nmemb, fp);
	return written;
}

int assetsManagerProgressFunc(void *ptr, double totalToDownload, double nowDownloaded, double totalToUpLoad, double nowUpLoaded)
{
	static int percent = 0;
	int tmp = 0;
	long localLen = *(long*)ptr;
	if ( totalToDownload > 0 )
	{
		tmp = (int)((nowDownloaded + (double)localLen) / (totalToDownload + (double)localLen) * 100);
	}
	
	printf("下载进度%0d%%\r", tmp);
	return 0;
}

long GetLocalFileLenth(const char* fileName)
{
	char strTemp[256] = {0};
	strcpy_s(strTemp,fileName);
	FILE* fp = fopen(strTemp, "rb");
	if(fp != NULL)
	{
		long localLen = _filelength(_fileno(fp));
		fclose(fp);
		return localLen;
	}
	return 0;
}

/************************************************************************/
/* 获取要下载的远程文件的大小 											*/
/************************************************************************/
long getDownloadFileLenth(const char *url){
	long downloadFileLenth = 0;
	CURL *handle = curl_easy_init();
	curl_easy_setopt(handle, CURLOPT_URL, url);
	curl_easy_setopt(handle, CURLOPT_HEADER, 1);    //只需要header头
	curl_easy_setopt(handle, CURLOPT_NOBODY, 1);    //不需要body
	if (curl_easy_perform(handle) == CURLE_OK) 
	{
		curl_easy_getinfo(handle, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &downloadFileLenth);
	} 
	else 
	{
		downloadFileLenth = -1;
	}
	return downloadFileLenth;
}

bool downLoad(void *_curl, std::string _packageUrl, std::string _storagePath, std::string fileName )
{
	// Create a file to save package.
	const string outFileName = _storagePath + fileName;
	//================断点续载===================
	long localLen = GetLocalFileLenth(outFileName.c_str());

	FILE *fp = fopen(outFileName.c_str(), "a+b");
	if (! fp)
	{
		return false;
	}
	fseek(fp, 0, SEEK_END);

	// Download pacakge
	CURLcode res;
	curl_easy_setopt(_curl, CURLOPT_URL, _packageUrl.c_str());
	curl_easy_setopt(_curl, CURLOPT_WRITEFUNCTION, downLoadPackage);
	curl_easy_setopt(_curl, CURLOPT_WRITEDATA, fp);
	curl_easy_setopt(_curl, CURLOPT_NOPROGRESS, false);
	curl_easy_setopt(_curl, CURLOPT_PROGRESSFUNCTION, assetsManagerProgressFunc);
	curl_easy_setopt(_curl, CURLOPT_NOSIGNAL, 1L);
	curl_easy_setopt(_curl, CURLOPT_LOW_SPEED_LIMIT, 1L);
	curl_easy_setopt(_curl, CURLOPT_LOW_SPEED_TIME, 5L);

	curl_easy_setopt(_curl, CURLOPT_HEADER, 0L);
	curl_easy_setopt(_curl, CURLOPT_NOBODY, 0L);
	curl_easy_setopt(_curl, CURLOPT_FOLLOWLOCATION, 1L);
	curl_easy_setopt(_curl, CURLOPT_RESUME_FROM, localLen);

	curl_easy_setopt(_curl, CURLOPT_PROGRESSDATA, &localLen);



	res = curl_easy_perform(_curl);
	curl_easy_cleanup(_curl);
	if (res != 0)
	{
		fclose(fp);
		return false;
	}

	fclose(fp);
	return true;
}

int _tmain(int argc, _TCHAR* argv[])
{
	CURL* _curl = curl_easy_init();
	if (! _curl)
	{
		return 0;
	}

	downLoad(_curl, "http://ardownload.adobe.com/pub/adobe/reader/win/11.x/11.0.01/en_US/AdbeRdr11001_en_US.exe", "./", "AdbeRdr11001_en_US.exe");
	//downLoad(_curl, "http://localhost/MyWebServer.rar", "./", "MyWebServer.rar");
	getchar();
	return 0;
}