curl_easy_perform在URL不正确时崩溃 [英] curl_easy_perform crashes when the URL is not correct

问题描述

我在尝试使用 libcurl 下载文件时出现问题。该程序使用多个线程，每个需要下载文件的线程创建一个 libcurl 句柄。

I have a problem trying to download files using libcurl. The program works with multiple threads, every thread that needs to download a file creates a libcurl handle to work with.

当URL正确时，一切正常，但如果在URL中有错误，程序崩溃。在调试模式下，如果URL不正确 curl_easy_perform 返回错误连接代码，程序工作。

When the URL is correct everything works, but if there is a mistake in the URL the program crashes. In debug mode, if the URL is not correct curl_easy_perform returns an error connection code and the program works. In contrast, it crashes in release.

这是一个代码，代码如下：

How could I fix this error?

我使用下载文件，不相关的代码已被拒绝：

Here is the code that I use to download the file, irrelevant code has been supressed:

LoadFileFromServer
(
    string& a_sURL
)
{
    string  sErrorBuffer;

    struct DownloadedFile updateFile = { sFilenameToWrite,  // name to store the local file if succesful
                                         NULL };            // temp buffer

    CURL*   pCurl = curl_easy_init();

    curl_easy_setopt( pCurl, CURLOPT_URL, a_sURL.data() );
    curl_easy_setopt( pCurl, CURLOPT_FOLLOWLOCATION, 1L );
    curl_easy_setopt( pCurl, CURLOPT_ERRORBUFFER, sErrorBuffer );
    curl_easy_setopt( pCurl, CURLOPT_WRITEFUNCTION, BufferToFile );
    curl_easy_setopt( pCurl, CURLOPT_WRITEDATA, &updateFile );
    curl_easy_setopt( pCurl, CURLOPT_NOPROGRESS, 0 );
    curl_easy_setopt( pCurl, CURLOPT_CONNECTTIMEOUT, 5L );

    CURLcode res = curl_easy_perform( pCurl );

    curl_easy_cleanup( pCurl );
}

int BufferToFile
( 
    void *  a_buffer, 
    size_t  a_nSize, 
    size_t  a_nMemb, 
    void *  a_stream 
)
{
    struct DownloadedFile *out = ( struct DownloadedFile * ) a_stream;
    if( out && !out->stream ) 
    {
        // open file for writing 
        if ( 0 != fopen_s( &( out->stream ), out->filename.c_str(), "wb" ) )
            return -1;
        if( !out->stream )
            return -1; /* failure, can't open file to write */
    }

    return fwrite( a_buffer, a_nSize, a_nMemb, out->stream );
}

推荐答案

libcurl要求给定的URL是指向可以读取的有效缓冲区的指针。

libcurl requires that the given URL is a pointer to a valid buffer it can read from. If it isn't, the fault is in your code.

如果你传递一个适当的指针到一个（零终止）字符串，该字符串可以是一个正确的URL或者不是，但libcurl不应该崩溃因为它（和我的知识，它不）。

If you pass a proper pointer to a (zero terminated) string, that string can be a correct URL or not, but libcurl should not crash because of it (and to my knowledge it doesn't).

这篇关于curl_easy_perform在URL不正确时崩溃的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！