从base64字符串渲染pdf文件

Question

I have pdf file which is encoded with base64. I created simple script for saving it as pdf file:

import base64
with open('pdf.b64', mode='r') as fpdf:
    with open('output.pdf', mode='wb') as output:
        base64.decode(fpdf, output)
        output.close()
    fpdf.close()

After the script runs, I have pdf file as expected, but it's broken. I decided to compare just any correct pdf file with the file I got and noticed that every line in correct pdf file ends with "^M", for example:

Correct pdf file header: %PDF-1.7^M

My pdf file header: %PDF-1.4

So, what am I doing wrong here?

Answer 1

I had a similar problem. I used the following function to generate and return a PDF file from a base64 encoded string in Django. (Tested only with Python 3.5)

def b64_to_pdf(b64content):
    import io as BytesIO
    import base64
    from django.http import HttpResponse

    buffer = BytesIO.BytesIO()
    content = base64.b64decode(b64content)
    buffer.write(content)

    response = HttpResponse(
        buffer.getvalue(),
        content_type="application/pdf",
    )
    response['Content-Disposition'] = 'inline;filename=some_file.pdf'
    return response

If you are not using Django, then you just need to figure out how to return the PDF file in a view or something like that. I use HttpResponse that handles various things for the response.

I can also use this function for any kind of b64 encoded string, so it's reusable across the project.