[Bug] Linearization crashes with doc.write() method

[zufj]

Describe the bug

When attempting to apply the linearization to a document while use the write()method generates the error "RuntimeError: cannot seek in buffer: No such file or directory". This does not happen when using the save() method.

To Reproduce

import fitz
doc = fitz.open(pdf_path)
# Works:
doc.save("linearized.pdf",garbage=0, deflate=False,linear=True)
# Returns error: "RuntimeError: cannot seek in buffer: No such file or directory"
linearized_pdf_bytes = doc.write(garbage=0, deflate=False,linear=True)

Expected behavior

The method should return the bytes of the linearized PDF data.

Your configuration (mandatory)

• Ubuntu 20.04
• Python 3.8.5
• PyMuPDF 1.17.7 installed through pip

3.8.5 (default, Jul 28 2020, 12:59:40)
[GCC 9.3.0]

PyMuPDF 1.17.7: Python bindings for the MuPDF 1.17.0 library.
Version date: 2020-09-14 06:33:06.
Built for Python 3.8 on Liinux (64-bit).

[JorjMcKie]

Sorry, there is no way to heal this, because it's done by the underlying C library MuPDF.
You must save to disk and re-read the result.
I will update the documentation accordingly.

[zufj]

Alright. Thanks for the quick answer and pyMuPDF! :)

[jloehel]

Sorry, there is no way to heal this, because it's done by the underlying C library MuPDF.
You must save to disk and re-read the result.
I will update the documentation accordingly.

Maybe this has changed in the meanwhile. The function pdf_write_document() is calling do_pdf_save_document() which considers the linear option. pdf_save_document() is also calling do_pdf_save_document().

		if (opts->do_linear)
			linearize(ctx, doc, opts);

https://github.com/ArtifexSoftware/mupdf/blob/19057a9569774591bb4b5e3709c94c9a0f9684ac/source/pdf/pdf-write.c#L3466-L3467

Please let me know if I can help in any way with the implementation.

edit: It really looks like that the seek function is not implemented for a output with buffer. (https://github.com/ArtifexSoftware/mupdf/blob/19057a9569774591bb4b5e3709c94c9a0f9684ac/source/fitz/output.c#L287-L291)