[Zlib-devel] apparent 1.2.7 windowBits == 0 (autodetection) bug

[Greg Roelofs]

> By experiment, the file nm-signal-100.png has a 'window bits' of 9 and
> requires one of 11 to read ok.

Oddly enough, I'm still not seeing that.  If I pass 9 to inflateInit2()
1.2.7, it decompresses happily, and inflateEnd() returns Z_OK.

Possibly pngcheck's zlib decoder code is broken in some way; it's certainly
not elegant (heh...none of pngcheck is, alas), but I haven't encountered an
obvious bug in it in quite a few years.  No clue why libpng's invocation
seems to need a window size four times bigger than pngcheck's.

Greg