我尝试使用libcurl来测试下载和上传速度。我在上传方面遇到了这个奇怪的问题：我通过ftp上传的文件系统地丢失了1个字节。请注意，我没有阅读文件，而是在read_callback的{{1}}中动态生成数据，因为我感兴趣的是速度并记录数据本身。请参阅下面的代码，该代码主要基于此示例：libcurl chkspeed example
curl当我运行这个时，我得到了这个输出：
ul_total_bytes = 1000000
ul_total_bytes = 1000000
获取时出错＆＃39; ftp：// xxx.xxx.xxx.xxx/curl_upload_test' ：转移了部分文件
但如果我发表评论#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <curl/curl.h>
#define UL_FTP_USR "user"
#define UL_FTP_PWD "password"
#define UL_TARGET_URL "ftp://xxx.xxx.xxx.xxx/curl_upload_test"
#define UL_SIZE 1000000
long ul_total_bytes = 0;
static size_t read_callback_full(void *ptr, size_t size, size_t nmemb, void *stream)
{
if(ul_total_bytes >= UL_SIZE) {
printf("ul_total_bytes = %d\n", ul_total_bytes);
return 0; // we stop upload at this point
}
char *pp = (char *) ptr;
int i = 0;
for(; i < size*nmemb; i++)
{
pp[i] = i;
ul_total_bytes += 1;
if(ul_total_bytes >= UL_SIZE) {
printf("ul_total_bytes = %d\n", ul_total_bytes);
return i; // if we reach UL_SIZE_LIM we send last payload
}
}
return i;
}
int main(int argc, char *argv[])
{
const char *url = UL_TARGET_URL;
CURL *curl_handle;
CURLcode res;
// init libcurl
curl_global_init(CURL_GLOBAL_ALL);
// init the curl session
curl_handle = curl_easy_init();
// specify URL to put
curl_easy_setopt(curl_handle, CURLOPT_URL, url);
//---------- FTP CREDENTIALS -----------
curl_easy_setopt(curl_handle, CURLOPT_USERNAME, UL_FTP_USR);
curl_easy_setopt(curl_handle, CURLOPT_PASSWORD, UL_FTP_PWD);
//--------------------------------------
// tell it to "upload" to the URL
curl_easy_setopt(curl_handle, CURLOPT_UPLOAD, 1L);
// bogus pointer. We don't read file, we generate data in read callback on the fly
int p = 0;
curl_easy_setopt(curl_handle, CURLOPT_READDATA, &p);
// register read callback
curl_easy_setopt(curl_handle, CURLOPT_READFUNCTION, read_callback_full);
// set the file size
curl_easy_setopt(curl_handle, CURLOPT_INFILESIZE_LARGE, UL_SIZE);
// some servers don't like requests that are made without a user-agent field, so we provide one
curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-speedchecker"); // useful here ???
// execute the request!
res = curl_easy_perform(curl_handle);
//if(CURLE_OK == res) {
double val;
// check for bytes downloaded
res = curl_easy_getinfo(curl_handle, CURLINFO_SIZE_UPLOAD, &val);
if((CURLE_OK == res) && (val>0))
printf("Data uploaded: %0.0f bytes.\n", val);
// check for average upload speed
res = curl_easy_getinfo(curl_handle, CURLINFO_SPEED_UPLOAD, &val);
if((CURLE_OK == res) && (val>0))
printf("Average upload speed: %0.3f kbyte/sec.\n", val / 1024);
// check for name resolution time
res = curl_easy_getinfo(curl_handle, CURLINFO_NAMELOOKUP_TIME, &val);
if((CURLE_OK == res) && (val>0))
printf("Name lookup time: %0.3f sec.\n", val);
// check for total time
res = curl_easy_getinfo(curl_handle, CURLINFO_TOTAL_TIME, &val);
if((CURLE_OK == res) && (val>0))
printf("Total time: %0.3f sec.\n", val);
//}
//else {
fprintf(stderr, "Error while fetching '%s' : %s\n", url, curl_easy_strerror(res));
//}
// cleanup curl stuff
curl_easy_cleanup(curl_handle);
// we're done with libcurl, so clean it up
curl_global_cleanup();
/*
curl_version_info_data *data = curl_version_info(CURLVERSION_NOW);
printf("Version: %s\n", data->version);
printf("Host: %s\n", data->host);
printf("SSL-Version: %s\n", data->ssl_version);
printf("Libz-Version: %s\n", data->libz_version);
*/
return 0;
}
，那么我就明白了：
ul_total_bytes = 1000000
ul_total_bytes = 1000000
上传的数据：999999字节。
平均上传速度：386.591千字节/秒。
名称查找时间：0.000秒。
总时间：2.526秒
获取时出错＆＃39; ftp：// xxx.xxx.xxx.xxx/curl_upload_test' ：没有错误
事实上，我在if(CURLE_OK == res)上找到的文件是999.999字节...
这是版本信息：
版本：7.21.1
主持人：i586-common_3_0-linux-gnu
SSL-Version：OpenSSL / 1.0.0a
Libz-Version：1.2.3
代码必须在嵌入式系统上运行，因此我几乎坚持使用制造商提供的ftp版本。