从命令行执行时 CGI C 输出正确，但从 web 请求执行时不正确

Question

代码:

#include <unistd.h>
#include <stdio.h>

typedef struct hddinfo
{
    char szDevice[4];
    char szMfg[64];
    char szModel[64];
    int nTemp;
} hddinfo;

int main( int argc, char *argv[] )
{

    setuid( 0 );

    hddinfo hdi[4] = {0};

    FILE *fp = popen("/usr/sbin/hddtemp /dev/sd[abcd]","r");
    if( NULL != fp )
    {

        for( int i = 0; i < 4; i++ )
            fscanf( fp,"/dev/%3[^:]: %64s %64[^:]: %d°C\n",&hdi[i].szDevice, &hdi[i].szMfg, &hdi[i].szModel, &hdi[i].nTemp );

        pclose( fp );

        printf( "Content-type: text/html\n\n" );
        printf( "<table id=\"hddtemp\">\n\t<tr>\n\t\t<th>Device</th>\n\t\t<th>Mfg</th>\n\t\t<th>Model</th>\n\t\t<th>Temp</th>\n\t</tr>\n" );
        for( int i = 0; i < 4; i++ )
            printf( "\t<tr>\n\t\t<td>%s</td>\n\t\t<td>%s</td>\n\t\t<td>%s</td>\n\t\t<td>%d&deg;C</td>\n\t</tr>\n", hdi[i].szDevice, hdi[i].szMfg, hdi[i].szModel, hdi[i].nTemp );
        printf( "</table>" );

    }
    else
        printf( "Status: 400 Bad Request\nContent-type: text/html\n\n" );

    return 0;
}

以 www-data 用户身份从命令行运行时的输出:

<table id="hddtemp">
    <tr>
        <th>Device</th>
        <th>Mfg</th>
        <th>Model</th>
        <th>Temp</th>
    </tr>
    <tr>
        <td>sda</td>
        <td>WDC</td>
        <td>WD2500AAKX-001CA0</td>
        <td>29&deg;C</td>
    </tr>
    <tr>
        <td>sdb</td>
        <td>WDC</td>
        <td>WD20EURS-63S48Y0</td>
        <td>30&deg;C</td>
    </tr>
    <tr>
        <td>sdc</td>
        <td>WDC</td>
        <td>WD20EURS-63S48Y0</td>
        <td>30&deg;C</td>
    </tr>
    <tr>
        <td>sdd</td>
        <td>WDC</td>
        <td>WD20EURS-63S48Y0</td>
        <td>30&deg;C</td>
    </tr>
</table>

通过网络浏览器访问时的输出:

<table id="hddtemp">
    <tr>
        <th>Device</th>
        <th>Mfg</th>
        <th>Model</th>
        <th>Temp</th>
    </tr>

    <tr>
        <td>sda</td>
        <td>WDC</td>
        <td>WD2500AAKX-001CA0</td>
        <td>29&deg;C</td>
    </tr>

    <tr>
        <td></td>
        <td></td>
        <td></td>
        <td>0&deg;C</td>
    </tr>
    <tr>
        <td></td>

        <td></td>
        <td></td>
        <td>0&deg;C</td>
    </tr>
    <tr>
        <td></td>
        <td></td>
        <td></td>

        <td>0&deg;C</td>
    </tr>
</table>

Answer 1

看起来您的 fscanf 调用中有非 ASCII 格式(用于度数符号)。

这很可能是您的解析停止的地方，因为从 CGI 中执行时 LANG=C，而在命令行上执行时它被设置为其他内容。