该文是wecenter学习笔记的一部分
上传图片并生成缩略图
这部分主要由两个模块合力完成
- core_upload
- core_image
上传图片
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('错误代码: '.AWS_APP::upload()->get_error())));
break;
case 'upload_invalid_filetype':
H::ajax_json_output(AWS_APP::RSM(null, -1, AWS_APP::lang()->_t('文件类型无效')));
break;
case 'upload_invalid_filesize':
H::ajax_json_output(AWS_APP::RSM(null, -1, AWS_APP::lang()->_t("文件尺寸过大,最大允许尺寸为 ".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( '上传失败, 请与管理员联系' )));
}
步骤
- 初始化（接受的文件类型、保存路径、是否必须是图片、最大文件尺寸）
- 接受上传文件
- 错误处理
实现
core_upload处理文件上传，涵盖了
文件存储和访问暴露
先会将文件存储到临时文件中，在完成后面的检查后再移动到目标目录
文件类型判定并只允许上传制定类型的文件(mimes)
根据上传文件的扩展名判定是否是allowed_types，
如果是图片文件，还会尝试获取图片尺寸（利用获取图片大小会解析图片头部信息的副作用）
另外还是通过函数finfo_file、file命令或者mime_content_type来分析文件的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)
$regexp = '/^([a-z\-]+\/[a-z0-9\-\.\+]+)(;\s.+)?$/';
-
优先先会尝试使用 ｀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; } } } -
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; } } } } } -
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; } } -
最后才会考虑用
getimagesizeif (function_exists('getimagesize')) { $imageinfo = @getimagesize($file['tmp_name']); if ($imageinfo['mime']) { $this->file_type = $imageinfo['mime']; return; } } $this->file_type = $file['type'];
文件大小检查
图片尺寸检查
文件名和文件内容安全校验（xss clean）
会去掉文件名中的各类非法字符
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);
** 文件内容的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
// ]/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;
处理步骤
- 调整内存
memory_limit为读入文件保留足够的内存 - 如果是图片文件，要求文件不能有任何html标签（
a|body|head|html|img|plaintext|pre|script|table|title） - 如果不是图片，只要不为空即可。
生成缩略图算法
使用
AWS_APP::image()->initialize(array(
'quality' => 90,
'source_image' => $upload_data['full_path'],
'new_image' => $thumb_file[$key],
'width' => $val['w'],
'height' => $val['h']
))->resize();
core_image负责缩略图的生成
- 生成指定大小的缩略图（resize）
- 可以选择输出到文件或者浏览器
resize的算法支持缩放和裁剪，并支持压缩到一定清晰度
** 缩放 **
-
IMAGE_CORE_SC_NOT_KEEP_SCALE
直接缩放或拉伸，不考虑比例
-
IMAGE_CORE_SC_BEST_RESIZE_WIDTH
优先匹配缩放后的目标宽度
-
IMAGE_CORE_SC_BEST_RESIZE_HEIGHT
高度优先匹配
** 裁剪 **
-
IMAGE_CORE_CM_DEFAULT
不裁剪
-
IMAGE_CORE_CM_LEFT_OR_TOP
对齐左上角，裁剪右下角
-
IMAGE_CORE_CM_MIDDLE
居中对齐，裁剪四周
-
IMAGE_CORE_CM_RIGHT_OR_BOTTOM
右下角对齐，裁剪左上角
实现
内部支持GD或ImageMagick来处理图片，支持jpg/png/gif三种格式的图片处理。
处理步骤：
-
根据图片的宽窄比计算目标缩放区域（优先按长边缩放）
system/core/image.php#imageProcessImageMagick
if ($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 = $this->source_image_w; } -
根据裁剪需求，设定目标区域
system/core/image.php#imageProcessImageMagick
switch ($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; -
根据缩放设置，计算出目标图片的真实尺寸
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; } } 按目标区域裁剪图片
缩放图片到目标尺寸
输出图片
具体到图片处理记得，根据库的不同，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 **
通过 imagecopyresampled或imagecopyresized可以一步作为裁剪和缩放
$func_resize($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);
表单防CSRF(Cross-site request forgery)的实现 ←o→ 对称加密