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#1 2020-10-08 12:00:54
Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
Hi,
I have a system that is compiled on Delphi 7 using mORMOt (last commit 1dee1951016b9ab7 in 2020-03-29).
The system receives an XML which has some PDF encoded in Base64. These PDF are stored in a TDocVariantData structure. Later, it is read in some form to show PDF's for user.
To show a PDF I need to save as a file, in temporary directory. My issue is that I cannot decode Base64 just using Base64Bin() function, but it works using the (old) Synapse lib. But I would like to rip of this lib for use just mORMot.
Consider this:
var
i: Integer;
fn: TFileName;
pdf: RawByteString;
begin
{...}
{ docs is a TDocVariantData...}
for i := 0 to docs.Count-1 do
begin
{find the correct PDF selected by user...}
pdf := docs._[i].S['pdf'];
// FileFromString(DecodeBase64(pdf), fn, True); //<< this works
FileFromString(Base64ToBin(pdf), fn, True); // << this does not
ShellExecute(fn); // starts Adobe PDF
end;
end;- synacode.DecodeBase64() from Synapse reads perfectly
- XML looks like UTF8
- I've tried to make some conversions, like UTF8ToString / StringToUF8, SynUnicodeTo ... etc, but in vain.
Any ideas?
best regards.
Last edited by mdbs99 (2020-10-08 18:28:34)
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#3 2020-10-08 18:15:00
Re: Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
Could you put the input text into a gist so that we reproduce it?
I couldn't send the private PDF so, I asked the other part to make a fake one.
Here https://gist.github.com/mdbs99/fb6ddf23 … 2fff7a82f7
The structure is:
<Parametros>
<docs>
<doc>
<nome>filename</nome>
<pdf>base64</pdf>
...
</Parametros>Offline
#5 2020-10-08 18:48:17
Re: Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
The other system, made in Java, uses a known lib (Apache, I think) to encode in Base64... So, I think it's a valid parser and because that I cannot ask them to change it. 
Is it possible to implement a workaround in mORMot?
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#7 2020-10-08 19:08:12
Re: Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
Of course I've test and it still doesn't working.
pdf := StringReplaceAll(docs._[i].S['pdf'], #13#10, '');
//FileFromString(DecodeBase64(pdf), fn, True);
FileFromString(Base64ToBin(pdf), fn, True);Offline
#8 2020-10-08 19:13:12
Re: Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
If it can helps, here an example how Synapse do this parser -> https://github.com/marado/synapse/blob/ … e.pas#L172
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#9 2020-10-08 19:37:39
- macfly
- Member
- From: Brasil
- Registered: 2016-08-20
- Posts: 374
Re: Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
I think this replace will be safer if you consider only #13 as a line break as well.
pdf := docs._[i].S['pdf'];
pdf := StringReplaceAll(pdf, #13#10, '');
pdf := StringReplaceAll(pdf, #13, '');NOTE: The order matters. You should replace #13#10 first, and then #13
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#11 2020-10-08 20:03:52
Re: Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
That is it, TrimControlChars(), worked.
I didn't know about this function thank you.
But, just thinking, if the data that I've provided is considered valid, shouldn't we add a TrimControlChars() call in Base64 functions before conversion?
I've asked the guy and we tested using Java.util (built-in) and Apache commons. Both add line feed in the output...
Last edited by mdbs99 (2020-10-08 20:04:22)
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#12 2020-10-08 20:29:15
Re: Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
I think this replace will be safer if you consider only #13 as a line break as well.
pdf := docs._[i].S['pdf']; pdf := StringReplaceAll(pdf, #13#10, ''); pdf := StringReplaceAll(pdf, #13, '');NOTE: The order matters. You should replace #13#10 first, and then #13
Thank you too. But I chose Arnaud's tip because it's cleaner.
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#13 2020-10-08 20:37:51
- macfly
- Member
- From: Brasil
- Registered: 2016-08-20
- Posts: 374
Re: Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
Has many functions that simplify everything in SynCommons and I always take a look.
But I didn't really know about this TrimControlChars function.
But based on what it does the name shouldn't be RemoveControlChars? 
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#14 2020-10-08 20:41:17
Re: Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
Line feeds are usual in base-64, but the problem is that they can be almost everywhere.
So it is not possible to pre-allocate the output buffer if there are some line feeds.
Our conversion routines expect pure base-64 characters, and pre-compute the resulting buffer size.
To be fair, our main usage was binary storage - e.g. for Blobs - as JSON string.
For our use case, our routines are very optimized and efficient. And also safer, since they detect any unexpected/invalid char in the input, whereas DecodeBase64() doesn't.
If you want to handle external base-64 content, as you need, just process the input as TrimControlChars().
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#15 2020-10-08 21:21:20
Re: Issue using Base64ToBin(), but it works using synacode.DecodeBase64()
Linebrakes in base64 It's already explained in this topic https://synopse.info/forum/viewtopic.php?id=5373
Link to the the universal convertor is already there. @ab, may be we add it to the trunk (we can even replace existed implementation)
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