Thread: redirect a spawned process's output, or how to read ZIP

Is there a way to read the contents of a zip file in C? I just need the file list, dates, sizes.

I realize I can

Code:

strcpy(this_path, "WZZIP");

	ret = _spawnl(P_WAIT, this_path, this_path, "-vbf", "test.zip", ">temp", NULL);

This does work up to a point. but the redirect does not work so I can not capture the program's output. I looked all over the place for how to set a spawned process's stdout but found no solution when using spawn().

... or pipe, or whatever (would be faster than intermediate temporary file, or could be the same)

I am perfectly willing to see any other easier way to read a ZIP file.

I've never done this in Windows, so maybe I'm missing something, but...

the redirect does not work so I can not capture the program's output

Redirecting only redirects stdout (i.e. anything they print with printf, etc).. An unzipping utility will specify new files to create and write to those - redirection doesn't work in that case.

So if you unzipped a file (using a separate utility) it would be best to unzip it to a temporary location and use that in your program. There may of course be libraries written for C to do this more cleanly, but I'm not familiar with any of them to give you recommendations. (Standard C does not provide for this - you either need an unzipping library from someone else, a separate program that does it all, or you'd need to learn the file format and write your own - the latter would be extremely difficult!)

Originally Posted by nonoob

Is there a way to read the contents of a zip file in C?

Try zziplib, in particular the zzip_opendir, and zzip_readdir functions should be of interest to you.

sean, no it's not an unzipping utility that I'm interested in. It so happens that the WinZip console .exe tool WZZIP can do that, but I'm just using it to dump a list of file names contained within the zip file (hence the flag -v). Sorry if that wasn't clear. It spews the list alright when I execute it in a console window, and it also redirects happily to a temp file using ">"... but the issue is when using spawn(). Can't seem to capture the tool's output.

Thanks, MWAAAHAAA , I'll take a look at that.