CGI实现文件的上传和下载

1.文件上传

       该功能通过使用cgic来实现。

(1)界面代码

 
                                 // 上传文件必须设置为post + multipart/form-data
	

	

	    
 上传配置文件 
	    

	    

	
	
	

	    
 下载配置文件 
	    
 配置文件导出地址 
	
	
    
    

(2)执行函数代码

enum ErrLog
{
    ErrSucceed,
    ErrOpenFile,
    ErrNoFile
};
enum ErrLog UploadFile()
{
    cgiFilePtr file;
    FILE *fd;
    char name[512];
    char path[128];
    char contentType[1024];
    int size = 0;
    int got = 0;
    int t = 0;
    char *tmp = NULL;

    if (cgiFormFileName("uploadfile", name, sizeof(name)) != cgiFormSuccess) //获取客户端pathname 
    {
        printf("
 No file was uploaded. 
\n");
        return ErrNoFile;
    }
    fprintf(cgiOut, "The filename submitted was: ");
    cgiHtmlEscape(name);
    fprintf(cgiOut, "
\n");
	
    cgiFormFileSize("uploadfile", &size);
    fprintf(cgiOut, "The file size was: %d bytes
\n", size);
	
    cgiFormFileContentType("uploadfile", contentType, sizeof(contentType));
    fprintf(cgiOut, "The alleged content type of the file was: ");
    cgiHtmlEscape(contentType);
    fprintf(cgiOut, "
\n");

    if (cgiFormFileOpen("uploadfile", &file) != cgiFormSuccess)  //尝试打开上传的，并存放在系统中的临时文件
    {
        fprintf(cgiOut, "
 Could not open the file. 
\n");
        return ErrOpenFile;
    }

    t = -1;
    while (1)
    {
        tmp = strstr(name+t+1, "\\");  // 从pathname解析出filename
        if (NULL == tmp)
        {
            tmp = strstr(name+t+1, "/");
        }
        if (NULL != tmp)
        {
            t = (int)(tmp-name);
        }
        else
        {
            break;
        }
    }
    tmp = (char *)malloc(size * sizeof(char)); // 在底层建立新文件
    strcpy(path, "/usr/local/boa/data/");
    strcat(path, name+t+1);  
    fd = fopen(path, "w+");
    if (fd == NULL)
    {
        return ErrOpenFile;
    }

    while (cgiFormFileRead(file, tmp, size, &got) == cgiFormSuccess) // 从临时文件读出content
    {
        fwrite(tmp, size, sizeof(char), fd);  //把读出的content写入新文件
    }
    fprintf(cgiOut, "
 Upload File Success. 
\n");

    cgiFormFileClose(file);
    free(tmp);
    fclose(fd);
    return ErrSucceed;
}

2.文件下载

(1)借助HTML中a标签实现，如：download="filename"> download ，则打开浏览器点击链接即可实现文件下载。

注：其中download属性可避免直接打开文件，进而执行下载任务；该方式的优点是在静态html界面即可实现文件下载，缺点是暴露了文件及其路径。

界面代码

		
    

    

    	
 xx设置 
    

    

    	
 xx模块 
    
    

    

(2)当然，上述操作借助了部分浏览器内嵌的功能，而对于另一部分浏览器来说必须通过后台代码来实现文件的读、写和存，间接实现文件的下载，该部分可参考《嵌入式Linux下基于CGI的文件上传下载的实现》。

执行代码

void download(char *filename)
{
    FIFE *fp;
    char buff[SIZE];
    struct stat s;
    time_t date;
    int n;

    date = time(NULL);
    stat(filename, &s);
    printf(“Content Disposition:filename=\“%s\” date=%s\n”, filename, ctime(&date));
    printf(“Content Length:size==%d\n”, s.st_size);
    if (fp = fopen(filename, “r”))
    {
        while ((n = fread(buff, sizeof(char), sizeof(buff), fp)) > 0)
        {
            fwrite(buff, n, 1, stdout)
        }
        fclose(fp);
    }
}