I am using pdftk
library to extract the form fields from the pdf .Everything is just running fine except the one issue that i got a pdf file pdf file link. which causes the error is given bellow
Error: Failed to open PDF file:
http://www.uscis.gov/sites/default/files/files/form/i-9.pdf
Done. Input errors, so no output created.
command for this is
root@ri8-MS-7788:/home/ri-8# pdftk http://192.168.1.43/form/i-9.pdf dump_data_fields
the same command is working for all other forms .
Attempt1
I have tried to encrypt the pdf to unsafe version but it produce the same error . here is the command
pdftk http://192.168.1.43/forms/i-9.pdf input_pw foopass output /var/www/forms/un-i-9.pdf
Update
this is my full function to handle this
public function Formanalysis($pdfname)
{
$pdffile=Yii::app()->getBaseUrl(true).'/uploads/forms/'.$pdfname;
exec("pdftk ".$pdffile." dump_data_fields 2>&1", $output,$retval);
//got an error for some pdf if these are secure
if(strpos($output[0],'Error') !== false)
{
$unsafepdf=Yii::getPathOfAlias('webroot').'/uploads/forms/un-'.$pdfname;
//echo "pdftk ".$pdffile." input_pw foopass output ".$unsafepdf;
exec("pdftk ".$pdffile." input_pw foopass output ".$unsafepdf);
exec("pdftk ".$unsafepdf." dump_data_fields 2>&1", $outputunsafe,$retval);
return $outputunsafe ;
//$response=array('0'=>'error','error'=>$output[0]);
//return $response;
}
//if (strpos($output[0],'Error') !== false){ echo "error to run" ; } // this is the option to handle error
return $output;
}
this may be a little trick solution but should work for you . as @bruno said that this is encrypted file . You should decrypt this before you use for the pdftk
. For this i found a way to decrypt that is qpdf
a free opem source library to decrypt the pdf, remove the owner and user passwords etc and many more. You can find this here Qpdf. install it on your system . and run this command
qpdf --decrypt input.pdf output.pdf
then use the output file in the pdftk
command . it should work .
PdfTk is a tool that was created by compiling an obsolete version of iText to an executable using the GNU Compiler for Java (GCJ) (PdfTk is not endorsed by iText Group NV).
I have examined your PDF and it uses two technologies that weren't supported by iText at the time PdfTk was created: XFA and compressed cross-reference tables.
The latter is what causes your problem. PdfTk expects your file to end like this:
xref
0 7
0000000000 65535 f
0000000258 00000 n
0000000015 00000 n
0000000346 00000 n
0000000146 00000 n
0000000397 00000 n
0000000442 00000 n
trailer
<</ID [<c8bf0ac531b0fc7b5b9ec5daf0296834><ec4dde54d00305ebbec62f3f6bbca974>]/Root 5 0 R/Size 7/Info 6 0 R>>
%iText-5.4.3
startxref
595
%%EOF
In this snippet startxref
marks the byte offset of xref
which is where the cross-reference table starts. This table contains the byte-offsets of all the objects in the PDF.
When you look at the PDF you refer to, you see that it ends like this:
64 0 obj
<</DecodeParms<</Columns 5/Predictor 12>>/Encrypt 972 0 R/Filter/FlateDecode/ID[<85C47EA3EFE49E4CB0F087350055FDDC><C3F1748360D0464FBA02D711DE864630>]/Info 970 0 R/Length 283/Root 973 0 R/Size 971/Type/XRef/W[1 3 1]>>stream
hÞìÒ±JQЙ·»7J¢©ÕØ(Xþ„ù »h%¤É¤¶”€mZ+;ÁN,,ÁÆ6 XÁ&‚("î½YŒI‘Bî‡áμ]ö1Áð÷³cfþ‹ûÐÚLî`z„Ýôœùw÷N×X?ÙkNv`hÁÒj¦G[œiÀå»›œ?b½Än…ÉëàÍþ gY—i7WW‡òj®îÍ°u¸Ò‡Ñ:óÆÛ™ñÎë&'×݈§ü†ù!ÿñ€ù%,\ácçÙ9˜ì±Þ€S¼Ãd—‰Áy~×.ø¶Åìþßn_˜$9Ôüw£X9#åxzçgRüüóÙwÝ¡œÄNJ©½’Ú+©½’R{%µWR{%ÿ·á”;`_ z6Ø
endstream
endobj
startxref
116
%%EOF
In this case, startxref
still refers to where the first cross-reference table starts (it's a linearized PDF), but the cross reference table is stored inside an object, and that object is compressed (see the gibberish between the stream
and endstream
keywords).
Compressed cross-reference tables and compressed objects were introduced in PDF 1.5 (2003), but they aren't supported by PdfTk. You'll have to find a tool that can deal with such streams (e.g. a recent version of iText, which is the real stuff when compared to PdfTk), or you have to save your PDF as a PDF 1.4 before you treat it with PdfTk (but you'll lose the XFA, because XFA was also introduced in PDF 1.5).
Update:
Since you are asking about form fields, I'm adding the following attachment:
This screenshot was taken using iText RUPS (which proves that iText can open the document). To the right, you see that the same form is defined twice:
If you would walk down the tree under Fields
, you'd find all the fields that are stored in the PDF using AcroForm technology. To the left, you can see the description of such a field:
If you look under XFA, you notice that the same form is also defined using the XML Forms Architecture. If you click on datasets
, you see the XML description of the dataset in the lower panel:
All of this information can be accessed programmatically using iText (Java) or iTextSharp (C#). PdfTk is merely a tool based on a very old version of this technology.
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