Archive for the ‘PHP’ Category

PHP count() is O(1)

I was curious about the performance of PHP’s count() function a while back and whether it was worth it to store the result in a variable for repeated use. I discovered the following from this answer by FractalizeR on Stack Overflow:

PHP_FUNCTION(count) calls php_count_recursive(), which in turn calls zend_hash_num_elements() for non-recursive array, which is implemented this way:

ZEND_API int zend_hash_num_elements(const HashTable *ht)
{
IS_CONSISTENT(ht);

return ht->nNumOfElements;
}

So you can see, it’s O(1) for $mode = COUNT_NORMAL.

IMAP Pickup

An interesting little project I wanted to work on; I wanted to be able to pull attachments from emails in an IMAP mailbox and then download them. I wanted an IMAP solution instead of writing a script for the MTA as a script would be specific to the MTA software and not transferable to another server. In addition, there’s also the common case where you may simply not have access to the MTA.

The biggest help in putting this together and dealing with attachments was this blog post and this comment on the PHP docs. Information on doing this is a bit scattered and incomplete in many cases, likely because extracting attachments is somewhat difficult as email is a notoriously bad way to transfer files; the file data is base64 encoded and dumped in as part of the message body.

ImapPickup is the class that encapsulates all the necessary functionality,

class ImapPickup
{
protected $imapStream = null;

protected function findAttachments($part)
{
$partNum = -1;
$attachments = array();

$this->findAttachmentsRec($part, &$attachments, &$partNum, -1);

return $attachments;
}

protected function findAttachmentsRec($part, &$attachments, &$partNum, $partNumSub)
{
if (isset($part->parts))
{
foreach ($part->parts as $partOfPart)
{
$this->findAttachmentsRec($partOfPart, &$attachments, &$partNum, $partNumSub+1);
}
}
else
{

if (isset($part->disposition)){
if ($part->disposition == 'attachment') {
$attachments[] = array($part->dparameters[0]->value, $partNum, $partNumSub);
}
}
}

$partNum++;
}

public function getAttachmentContent($msgNum, $partNum)
{
$contents = imap_fetchbody($this->imapStream, $msgNum, $partNum, FT_UID);
return imap_base64($contents);
}

public function getAttachments($msgNum)
{
$struct = imap_fetchstructure($this->imapStream,$msgNum,FT_UID);
$attachments = $this->findAttachments($struct);

return $attachments;
}

public function getAttachmentsFromMessages($msgArray)
{
$msgIdToAttachmentsMap = array();

if ($msgArray)
{
foreach($msgArray as $msgId)
{
$attachments = $this->getAttachments($msgId);
if(!empty($attachments))
{
$msgIdToAttachmentsMap[$msgId] = $attachments;
}
}
}

return $msgIdToAttachmentsMap;
}

public function getMessages($searchQuery)
{
return imap_search($this->imapStream, $searchQuery, SE_UID);
}

public function connect($mailbox, $user, $password)
{
$this->imapStream = imap_open($mailbox, $user, $password);
}

public function disconnect()
{
imap_close(
$this->imapStream);
}

}

Here’s a little example of how it can be used. This will query all messages with “pickup::” in the subject line and print out the messageID of all messages with attachments, followed by the filenames of all attachments for that message.

$imapPickup = new ImapPickup();
$imapPickup->connect("{mail.hotspotdot.net:143}INBOX", "test@test.net", "pass123");

$messages = $imapPickup->getMessages("SUBJECT pickup::");
$attachments = $imapPickup->getAttachmentsFromMessages($messages);

foreach($attachments as $msgId => $attArr)
{
echo "<p>{$msgId} => ";

foreach($attArr as $attachment)
{
echo $attachment[0];
echo ",";
}

echo "</p>";
}

$imapPickup->disconnect();

The array for a single file attachment contains 3 entries:

  • [0] => filename
  • [1] => major part number
  • [2] => minor part number

getAttachments(), findAttachments(), and findAttachmentsRec() will return an array of such entries (or an empty array is there are no attachments). getAttachmentsFromMessages() will return a map from messageID => array of single attachments.

The part number (both major and minor) is needed to retrieve the contents of an attachment. For getAttachmentContent(), simply use the major number if the minor number is <= 0, or concatenate them with a period separating them (e.g. "2.3").

PHP session_start() “Node no longer exists”

I stumbled upon this error earlier today as I attempted to store the value of a SimpleXMLElement as a session variable. I was able to narrow down the issue thanks to this post on bytes.com.

According to a user post on the PHP site, this occurs because SimpleXML returns a reference to an object containing the node value, and you can’t store a reference as a session variable. The value must be dereferenced and copied which can be done by casting.

// Bad! $storageBoxSize = $xml->data->storage_box_size;

// Good! $storageBoxSize = (int)$xml->data->storage_box_size;

I find myself hating loosely-typed languages more and more.

PHP Array of MIME Types

Useful for when you need to set HTTP headers when serving file downloads. The mime_content_type function is deprecated and in my case was just returning an empty string. The recommended alternative, using PECL finfo_file, should work fine, but adding and compiling in a PECL extension just for this seems like overkill, especially as you have more control using an array. I’m also never crazy about adding dependencies unless they’re absolutely necessary.

This is from snipplr, but includes the image/png type which was, curiously, missing.

$mime_types = array(
"323" => "text/h323",
"acx" => "application/internet-property-stream",
"ai" => "application/postscript",
"aif" => "audio/x-aiff",
"aifc" => "audio/x-aiff",
"aiff" => "audio/x-aiff",
"asf" => "video/x-ms-asf",
"asr" => "video/x-ms-asf",
"asx" => "video/x-ms-asf",
"au" => "audio/basic",
"avi" => "video/x-msvideo",
"axs" => "application/olescript",
"bas" => "text/plain",
"bcpio" => "application/x-bcpio",
"bin" => "application/octet-stream",
"bmp" => "image/bmp",
"c" => "text/plain",
"cat" => "application/vnd.ms-pkiseccat",
"cdf" => "application/x-cdf",
"cer" => "application/x-x509-ca-cert",
"class" => "application/octet-stream",
"clp" => "application/x-msclip",
"cmx" => "image/x-cmx",
"cod" => "image/cis-cod",
"cpio" => "application/x-cpio",
"crd" => "application/x-mscardfile",
"crl" => "application/pkix-crl",
"crt" => "application/x-x509-ca-cert",
"csh" => "application/x-csh",
"css" => "text/css",
"dcr" => "application/x-director",
"der" => "application/x-x509-ca-cert",
"dir" => "application/x-director",
"dll" => "application/x-msdownload",
"dms" => "application/octet-stream",
"doc" => "application/msword",
"dot" => "application/msword",
"dvi" => "application/x-dvi",
"dxr" => "application/x-director",
"eps" => "application/postscript",
"etx" => "text/x-setext",
"evy" => "application/envoy",
"exe" => "application/octet-stream",
"fif" => "application/fractals",
"flr" => "x-world/x-vrml",
"gif" => "image/gif",
"gtar" => "application/x-gtar",
"gz" => "application/x-gzip",
"h" => "text/plain",
"hdf" => "application/x-hdf",
"hlp" => "application/winhlp",
"hqx" => "application/mac-binhex40",
"hta" => "application/hta",
"htc" => "text/x-component",
"htm" => "text/html",
"html" => "text/html",
"htt" => "text/webviewhtml",
"ico" => "image/x-icon",
"ief" => "image/ief",
"iii" => "application/x-iphone",
"ins" => "application/x-internet-signup",
"isp" => "application/x-internet-signup",
"jfif" => "image/pipeg",
"jpe" => "image/jpeg",
"jpeg" => "image/jpeg",
"jpg" => "image/jpeg",
"js" => "application/x-javascript",
"latex" => "application/x-latex",
"lha" => "application/octet-stream",
"lsf" => "video/x-la-asf",
"lsx" => "video/x-la-asf",
"lzh" => "application/octet-stream",
"m13" => "application/x-msmediaview",
"m14" => "application/x-msmediaview",
"m3u" => "audio/x-mpegurl",
"man" => "application/x-troff-man",
"mdb" => "application/x-msaccess",
"me" => "application/x-troff-me",
"mht" => "message/rfc822",
"mhtml" => "message/rfc822",
"mid" => "audio/mid",
"mny" => "application/x-msmoney",
"mov" => "video/quicktime",
"movie" => "video/x-sgi-movie",
"mp2" => "video/mpeg",
"mp3" => "audio/mpeg",
"mpa" => "video/mpeg",
"mpe" => "video/mpeg",
"mpeg" => "video/mpeg",
"mpg" => "video/mpeg",
"mpp" => "application/vnd.ms-project",
"mpv2" => "video/mpeg",
"ms" => "application/x-troff-ms",
"mvb" => "application/x-msmediaview",
"nws" => "message/rfc822",
"oda" => "application/oda",
"p10" => "application/pkcs10",
"p12" => "application/x-pkcs12",
"p7b" => "application/x-pkcs7-certificates",
"p7c" => "application/x-pkcs7-mime",
"p7m" => "application/x-pkcs7-mime",
"p7r" => "application/x-pkcs7-certreqresp",
"p7s" => "application/x-pkcs7-signature",
"pbm" => "image/x-portable-bitmap",
"pdf" => "application/pdf",
"pfx" => "application/x-pkcs12",
"pgm" => "image/x-portable-graymap",
"pko" => "application/ynd.ms-pkipko",
"pma" => "application/x-perfmon",
"pmc" => "application/x-perfmon",
"pml" => "application/x-perfmon",
"pmr" => "application/x-perfmon",
"pmw" => "application/x-perfmon",
"png" => "image/png",
"pnm" => "image/x-portable-anymap",
"pot" => "application/vnd.ms-powerpoint",
"ppm" => "image/x-portable-pixmap",
"pps" => "application/vnd.ms-powerpoint",
"ppt" => "application/vnd.ms-powerpoint",
"prf" => "application/pics-rules",
"ps" => "application/postscript",
"pub" => "application/x-mspublisher",
"qt" => "video/quicktime",
"ra" => "audio/x-pn-realaudio",
"ram" => "audio/x-pn-realaudio",
"ras" => "image/x-cmu-raster",
"rgb" => "image/x-rgb",
"rmi" => "audio/mid",
"roff" => "application/x-troff",
"rtf" => "application/rtf",
"rtx" => "text/richtext",
"scd" => "application/x-msschedule",
"sct" => "text/scriptlet",
"setpay" => "application/set-payment-initiation",
"setreg" => "application/set-registration-initiation",
"sh" => "application/x-sh",
"shar" => "application/x-shar",
"sit" => "application/x-stuffit",
"snd" => "audio/basic",
"spc" => "application/x-pkcs7-certificates",
"spl" => "application/futuresplash",
"src" => "application/x-wais-source",
"sst" => "application/vnd.ms-pkicertstore",
"stl" => "application/vnd.ms-pkistl",
"stm" => "text/html",
"svg" => "image/svg+xml",
"sv4cpio" => "application/x-sv4cpio",
"sv4crc" => "application/x-sv4crc",
"t" => "application/x-troff",
"tar" => "application/x-tar",
"tcl" => "application/x-tcl",
"tex" => "application/x-tex",
"texi" => "application/x-texinfo",
"texinfo" => "application/x-texinfo",
"tgz" => "application/x-compressed",
"tif" => "image/tiff",
"tiff" => "image/tiff",
"tr" => "application/x-troff",
"trm" => "application/x-msterminal",
"tsv" => "text/tab-separated-values",
"txt" => "text/plain",
"uls" => "text/iuls",
"ustar" => "application/x-ustar",
"vcf" => "text/x-vcard",
"vrml" => "x-world/x-vrml",
"wav" => "audio/x-wav",
"wcm" => "application/vnd.ms-works",
"wdb" => "application/vnd.ms-works",
"wks" => "application/vnd.ms-works",
"wmf" => "application/x-msmetafile",
"wps" => "application/vnd.ms-works",
"wri" => "application/x-mswrite",
"wrl" => "x-world/x-vrml",
"wrz" => "x-world/x-vrml",
"xaf" => "x-world/x-vrml",
"xbm" => "image/x-xbitmap",
"xla" => "application/vnd.ms-excel",
"xlc" => "application/vnd.ms-excel",
"xlm" => "application/vnd.ms-excel",
"xls" => "application/vnd.ms-excel",
"xlt" => "application/vnd.ms-excel",
"xlw" => "application/vnd.ms-excel",
"xof" => "x-world/x-vrml",
"xpm" => "image/x-xpixmap",
"xwd" => "image/x-xwindowdump",
"z" => "application/x-compress",
"zip" => "application/zip" );

Altering the file size limit for PHP uploads

Well, of course, you can edit php.ini to change the file size limit, but for cheap (typically, shared) hosting solutions the issue that pops us is that you don’t have access to it.

I was researching how I could do this w/o modifying php.ini and discovered a forum post that explain a few methods of how it could be done.

Method A (the one that worked for me):
Edit your .htaccess file (if you don’t have one in your web site’s public root directory, you should be able to just create one) and add the following:
php_value post_max_size 8M
php_value upload_max_filesize 8M
(of course, replace 8M with however many megabytes you wish to limit the file sizes of uploads by)

Method B (the one that didn’t work for me):
Use the ini_set function,
ini_set('post_max_size', '8M');
ini_set('upload_max_filesize', '8M');

Method C (the one I didn’t try):
Use a custom php.ini. Not sure exactly what would be involved here, but you’d likely have to programmatically make a copy of the existing php.ini file, modify the copy, and then place the copy in the directory of the script that needs it or in your web site’s public root directory.