Julia: Extract Zip files within a Zip file

Question

I'm using Julia's ZipFile package to extract and process csv files. No problem, but when I encounter a zip file within the zip file, I'd like to process that as well, but am encountering an error.

Julia ZipFile docs are here: https://zipfilejl.readthedocs.io/en/latest/

Here's the code:

using ZipFile
using DataFrames
function process_zip(zip::ZipFile.ReadableFile)

    if split(zip.name,".")[end] == "zip"

        r = ZipFile.Reader(zip) #error: MethodError: no method matching seekend(::ZipFile.ReadableFile)

        for f in r.files
            process_zip(f) 
        end
    end

    if split(zip.name,".")[end] == "csv"
         df = readtable(zip) #for now just read it into a dataframe
    end

end

r = ZipFile.Reader("yourzipfilepathhere");

for f in r.files
    process_zip(f)
end
close(r)

The call to ZipFile.Reader gives the error:

MethodError: no method matching seekend(::ZipFile.ReadableFile)
Closest candidates are:
  seekend(::Base.Filesystem.File) at filesystem.jl:191
  seekend(::IOStream) at iostream.jl:57
  seekend(::Base.AbstractIOBuffer) at iobuffer.jl:178
  ...

Stacktrace:
 [1] _find_enddiroffset(::ZipFile.ReadableFile) at /home/chuck/.julia/v0.6/ZipFile/src/ZipFile.jl:259
 [2] ZipFile.Reader(::ZipFile.ReadableFile, ::Bool) at /home/chuck/.julia/v0.6/ZipFile/src/ZipFile.jl:104
 [3] process_zip(::ZipFile.ReadableFile) at ./In[27]:7
 [4] macro expansion at ./In[27]:18 [inlined]
 [5] anonymous at ./<missing>:?

So it seems ZipFile package cannot process a zip file from a zip file as it cannot do a seekend on it.

Any ideas on how to do this?

Answer 1

A workaround is to read the zip file into an IOBuffer. ZipFile.Reader is able to process the IOBuffer. Here is the working code:

using ZipFile
using DataFrames
function process_zip(zip::ZipFile.ReadableFile)

    if split(zip.name,".")[end] == "zip"

        iobuffer = IOBuffer(readstring(zip))
        r = ZipFile.Reader(iobuffer)

        for f in r.files
            process_zip(f) 
        end
    end

    if split(zip.name,".")[end] == "csv"
         df = readtable(zip) #for now just read it into a dataframe
    end

end

r = ZipFile.Reader("yourzipfilepathhere");

for f in r.files
    process_zip(f)
end
close(r)