wecenter學(xué)習(xí)筆記-上傳圖片并生成縮略圖

該文是wecenter學(xué)習(xí)筆記的一部分

上傳圖片并生成縮略圖

這部分主要由兩個模塊合力完成

  • core_upload
  • core_image

上傳圖片

使用

AWS_APP::upload()->initialize(array(
    'allowed_types' => get_setting('allowed_upload_types'),
    'upload_path' => get_setting('upload_dir') . '/' . $item_type . '/' . gmdate('Ymd'),
    'is_image' => FALSE,
    'max_size' => get_setting('upload_size_limit')
));

...

AWS_APP::upload()->do_upload('qqfile');

...

if (AWS_APP::upload()->get_error())
{
    switch (AWS_APP::upload()->get_error())
    {
        default:
            H::ajax_json_output(AWS_APP::RSM(null, -1, AWS_APP::lang()->_t('錯誤代碼: '.AWS_APP::upload()->get_error())));
        break;

        case 'upload_invalid_filetype':
            H::ajax_json_output(AWS_APP::RSM(null, -1, AWS_APP::lang()->_t('文件類型無效')));
        break;

        case 'upload_invalid_filesize':
           H::ajax_json_output(AWS_APP::RSM(null, -1, AWS_APP::lang()->_t("文件尺寸過大,最大允許尺寸為 ".get_setting('upload_size_limit')." KB")));
        break;
    }
}

if (! $upload_data = AWS_APP::upload()->data())
{
    H::ajax_json_output(AWS_APP::RSM(null, -1, AWS_APP::lang()->_t( '上傳失敗, 請與管理員聯(lián)系' )));
}

步驟

  • 初始化（接受的文件類型、保存路徑、是否必須是圖片、最大文件尺寸）
  • 接受上傳文件
  • 錯誤處理

實現(xiàn)

core_upload處理文件上傳，涵蓋了

文件存儲和訪問暴露

先會將文件存儲到臨時文件中，在完成后面的檢查后再移動到目標目錄

文件類型判定并只允許上傳制定類型的文件(mimes)

根據(jù)上傳文件的擴展名判定是否是allowed_types，
如果是圖片文件，還會嘗試獲取圖片尺寸（利用獲取圖片大小會解析圖片頭部信息的副作用）
另外還是通過函數(shù)finfo_file、file命令或者mime_content_type來分析文件的mimes type

system/core/upload.php#file_mime_type

// We'll need this to validate the MIME info string (e.g. text/plain; charset=us-ascii)
   $regexp = '/^([a-z\-]+\/[a-z0-9\-\.\+]+)(;\s.+)?$/';

  1. 優(yōu)先先會嘗試使用 ｀finfo_file｀

    /* Fileinfo extension - most reliable method
 *
 * Unfortunately, prior to PHP 5.3 - it's only available as a PECL extension and the
 * more convenient FILEINFO_MIME_TYPE flag doesn't exist.
 */
if (function_exists('finfo_file'))
{
    $finfo = finfo_open(FILEINFO_MIME);
    if (is_resource($finfo)) // It is possible that a FALSE value is returned, if there is no magic MIME database file found on the system
    {
        $mime = @finfo_file($finfo, $file['tmp_name']);
        finfo_close($finfo);

        /* According to the comments section of the PHP manual page,
         * it is possible that this function returns an empty string
         * for some files (e.g. if they don't exist in the magic MIME database)
         */
        if (is_string($mime) && preg_match($regexp, $mime, $matches))
        {
            $this->file_type = $matches[1];
            return;
        }
    }
}

  2. 其次是file --brief --mime命令

    /* This is an ugly hack, but UNIX-type systems provide a "native" way to detect the file type,
 * which is still more secure than depending on the value of $_FILES[$field]['type'], and as it
 * was reported in issue #750 (https://github.com/EllisLab/CodeIgniter/issues/750) - it's better
 * than mime_content_type() as well, hence the attempts to try calling the command line with
 * three different functions.
 *
 * Notes:
 *  - the DIRECTORY_SEPARATOR comparison ensures that we're not on a Windows system
 *  - many system admins would disable the exec(), shell_exec(), popen() and similar functions
 *    due to security concerns, hence the function_exists() checks
 */
if (DIRECTORY_SEPARATOR !== '\\')
{
    $cmd = 'file --brief --mime ' . @escapeshellarg($file['tmp_name']) . ' 2>&1';

    if (function_exists('exec'))
    {
        /* This might look confusing, as $mime is being populated with all of the output when set in the second parameter.
         * However, we only neeed the last line, which is the actual return value of exec(), and as such - it overwrites
         * anything that could already be set for $mime previously. This effectively makes the second parameter a dummy
         * value, which is only put to allow us to get the return status code.
         */
        $mime = @exec($cmd, $mime, $return_status);
        if ($return_status === 0 && is_string($mime) && preg_match($regexp, $mime, $matches))
        {
            $this->file_type = $matches[1];
            return;
        }
    }

    if ( (bool) @ini_get('safe_mode') === FALSE && function_exists('shell_exec'))
    {
        $mime = @shell_exec($cmd);
        if (strlen($mime) > 0)
        {
            $mime = explode("\n", trim($mime));
            if (preg_match($regexp, $mime[(count($mime) - 1)], $matches))
            {
                $this->file_type = $matches[1];
                return;
            }
        }
    }

    if (function_exists('popen'))
    {
        $proc = @popen($cmd, 'r');
        if (is_resource($proc))
        {
            $mime = @fread($proc, 512);
            @pclose($proc);
            if ($mime !== FALSE)
            {
                $mime = explode("\n", trim($mime));
                if (preg_match($regexp, $mime[(count($mime) - 1)], $matches))
                {
                    $this->file_type = $matches[1];
                    return;
                }
            }
        }
    }
}

  3. 然后 mime_content_type

    // Fall back to the deprecated mime_content_type(), if available (still better than $_FILES[$field]['type'])
if (function_exists('mime_content_type'))
{
    $this->file_type = @mime_content_type($file['tmp_name']);
    if (strlen($this->file_type) > 0) // It's possible that mime_content_type() returns FALSE or an empty string
    {
        return;
    }
}

  4. 最后才會考慮用 getimagesize

    if (function_exists('getimagesize'))
{
    $imageinfo = @getimagesize($file['tmp_name']);

    if ($imageinfo['mime'])
    {
        $this->file_type = $imageinfo['mime'];

        return;
    }
}

$this->file_type = $file['type'];

文件大小檢查

圖片尺寸檢查

文件名和文件內(nèi)容安全校驗（xss clean）

會去掉文件名中的各類非法字符

system/core/upload.php#clean_file_name

    $bad = array(
                   "<!--",
                   "-->",
                   "'",
                   "<",
                   ">",
                   '"',
                   '&',
                   '$',
                   '=',
                   ';',
                   '?',
                   '/',
                   "%20",
                   "%22",
                   "%3c",      // <
                   "%253c",    // <
                   "%3e",      // >
                   "%0e",      // >
                   "%28",      // (
                   "%29",      // )
                   "%2528",    // (
                   "%26",      // &
                   "%24",      // $
                   "%3f",      // ?
                   "%3b",      // ;
                   "%3d"       // =
               );

   $filename = str_replace($bad, '', $filename);

** 文件內(nèi)容的xss clean **

system/core/upload.php#do_xss_clean

if (function_exists('memory_get_usage') && memory_get_usage() && ini_get('memory_limit') != '')
{
    $current = ini_get('memory_limit') * 1024 * 1024;

    // There was a bug/behavioural change in PHP 5.2, where numbers over one million get output
    // into scientific notation.  number_format() ensures this number is an integer
    // http://bugs.php.net/bug.php?id=43053

    $new_memory = number_format(ceil(filesize($file) + $current), 0, '.', '');

    @ini_set('memory_limit', $new_memory); // When an integer is used, the value is measured in bytes. - PHP.net
}

// If the file being uploaded is an image, then we should have no problem with XSS attacks (in theory), but
// IE can be fooled into mime-type detecting a malformed image as an html file, thus executing an XSS attack on anyone
// using IE who looks at the image.  It does this by inspecting the first 255 bytes of an image.  To get around this
// CI will itself look at the first 255 bytes of an image to determine its relative safety.  This can save a lot of
// processor power and time if it is actually a clean image, as it will be in nearly all instances _except_ an
// attempted XSS attack.

if (function_exists('getimagesize') && @getimagesize($file) !== FALSE)
{
    if (($file = @fopen($file, 'rb')) === FALSE) // "b" to force binary
    {
        return FALSE; // Couldn't open the file, return FALSE
    }

    $opening_bytes = fread($file, 256);
    fclose($file);

    // These are known to throw IE into mime-type detection chaos
    // <a, <body, <head, <html, <img, <plaintext, <pre, <script, <table, <title
    // title is basically just in SVG, but we filter it anyhow

    if ( ! preg_match('/<(a|body|head|html|img|plaintext|pre|script|table|title)[\s>]/i', $opening_bytes))
    {
        return TRUE; // its an image, no "triggers" detected in the first 256 bytes, we're good
    }
    else
    {
        return FALSE;
    }
}

if (($data = @file_get_contents($file)) === FALSE)
{
    return FALSE;
}

return $data;

處理步驟

  1. 調(diào)整內(nèi)存memory_limit為讀入文件保留足夠的內(nèi)存
  2. 如果是圖片文件，要求文件不能有任何html標簽（a|body|head|html|img|plaintext|pre|script|table|title）
  3. 如果不是圖片，只要不為空即可。

生成縮略圖算法

使用

AWS_APP::image()->initialize(array(
    'quality' => 90,
    'source_image' => $upload_data['full_path'],
    'new_image' => $thumb_file[$key],
    'width' => $val['w'],
    'height' => $val['h']
))->resize();

core_image負責(zé)縮略圖的生成

  • 生成指定大小的縮略圖（resize）
  • 可以選擇輸出到文件或者瀏覽器

resize的算法支持縮放和裁剪，并支持壓縮到一定清晰度

** 縮放 **

  • IMAGE_CORE_SC_NOT_KEEP_SCALE

    直接縮放或拉伸，不考慮比例

  • IMAGE_CORE_SC_BEST_RESIZE_WIDTH

    優(yōu)先匹配縮放后的目標寬度

  • IMAGE_CORE_SC_BEST_RESIZE_HEIGHT

    高度優(yōu)先匹配

** 裁剪 **

  • IMAGE_CORE_CM_DEFAULT

    不裁剪

  • IMAGE_CORE_CM_LEFT_OR_TOP

    對齊左上角，裁剪右下角

  • IMAGE_CORE_CM_MIDDLE

    居中對齊，裁剪四周

  • IMAGE_CORE_CM_RIGHT_OR_BOTTOM

    右下角對齊，裁剪左上角

實現(xiàn)

內(nèi)部支持GD或ImageMagick來處理圖片，支持jpg/png/gif三種格式的圖片處理。

處理步驟：

  1. 根據(jù)圖片的寬窄比計算目標縮放區(qū)域（優(yōu)先按長邊縮放）

    system/core/image.php#imageProcessImageMagick

    if ($this->source_image_w * $this->height > $this->source_image_h * $this->width)
{
    $match_w = round($this->width * $this->source_image_h / $this->height);
    $match_h = $this->source_image_h;
}
else
{
    $match_h = round($this->height * $this->source_image_w / $this->width);
    $match_w = $this->source_image_w;
}

  2. 根據(jù)裁剪需求，設(shè)定目標區(qū)域

    system/core/image.php#imageProcessImageMagick

    switch ($this->clipping)
{
    case IMAGE_CORE_CM_LEFT_OR_TOP:
        $this->source_image_x = 0;
        $this->source_image_y = 0;
    break;

    case IMAGE_CORE_CM_MIDDLE:
        $this->source_image_x = round(($this->source_image_w - $match_w) / 2);
        $this->source_image_y = round(($this->source_image_h - $match_h) / 2);
    break;

    case IMAGE_CORE_CM_RIGHT_OR_BOTTOM:
        $this->source_image_x = $this->source_image_w - $match_w;
        $this->source_image_y = $this->source_image_h - $match_h;
    break;
}

$this->source_image_w = $match_w;
$this->source_image_h = $match_h;
$this->source_image_x += $this->start_x;
$this->source_image_y += $this->start_y;

  3. 根據(jù)縮放設(shè)置，計算出目標圖片的真實尺寸

    system/core/image.php#imageProcessImageMagick

    $resize_height = $this->height;
$resize_width = $this->width;

if ($this->scale != IMAGE_CORE_SC_NOT_KEEP_SCALE)
{
    if ($this->scale == IMAGE_CORE_SC_BEST_RESIZE_WIDTH)
    {
        $resize_height = round($this->width * $this->source_image_h / $this->source_image_w);
        $resize_width = $this->width;
    }
    else if ($this->scale == IMAGE_CORE_SC_BEST_RESIZE_HEIGHT)
    {
        $resize_width = round($this->height * $this->source_image_w / $this->source_image_h);
        $resize_height = $this->height;
    }
}

  4. 按目標區(qū)域裁剪圖片

  5. 縮放圖片到目標尺寸

  6. 輸出圖片

具體到圖片處理記得，根據(jù)庫的不同，略有不同

** imagemagick **

$im = new Imagick();

$im->readimageblob(file_get_contents($this->source_image));

$im->setCompressionQuality($this->quality);

if ($this->source_image_x OR $this->source_image_y)
{
    $im->cropImage($this->source_image_w, $this->source_image_h, $this->source_image_x, $this->source_image_y);
}

$im->thumbnailImage($resize_width, $resize_height, true);

if ($this->option == IMAGE_CORE_OP_TO_FILE AND $this->new_image)
{
    file_put_contents($this->new_image, $im->getimageblob());
}
else if ($this->option == IMAGE_CORE_OP_OUTPUT)
{
    $output = $im->getimageblob();
            $outputtype = $im->getFormat();

    header("Content-type: $outputtype");
    echo $output;
    die;
}

** gd **

通過 imagecopyresampled或imagecopyresized可以一步作為裁剪和縮放

$func_resize($dst_img, $im, $dst_x, $dst_y, $this->source_image_x, $this->source_image_y, $fdst_w, $fdst_h, $this->source_image_w, $this->source_image_h);

表單防CSRF(Cross-site request forgery)的實現(xiàn) ←o→ 對稱加密

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