Hi brian, On Sat, 13 Apr 2019, brian m. carlson wrote:
> On Fri, Apr 12, 2019 at 09:51:02PM -0400, Jeff King wrote: > > I wondered how you were going to kick this in, since users can define > > arbitrary filters. I think it's kind of neat to automagically convert > > "gzip -cn" (which also happens to be the default). But I think we should > > mention that in the Documentation, in case somebody tries to use a > > custom version of gzip and wonders why it isn't kicking in. > > > > Likewise, it might make sense in the tests to put a poison gzip in the > > $PATH so that we can be sure we're using our internal code, and not just > > calling out to gzip (on platforms that have it, of course). > > > > The alternative is that we could use a special token like ":zlib" or > > something to indicate that the internal implementation should be used > > (and then tweak the baked-in default, too). That might be less > > surprising for users, but most people would still get the benefit since > > they'd be using the default config. > > I agree that a special value (or NULL, if that's possible) would be > nicer here. That way, if someone does specify a custom gzip, we honor > it, and it serves to document the code better. For example, if someone > symlinked pigz to gzip and used "gzip -cn", then they might not get the > parallelization benefits they expected. I went with `:zlib`. The `NULL` value would not really work, as there is no way to specify that via `archive.tgz.command`. About the symlinked thing: I do not really want to care to support such hacks. If you want a different compressor than the default (which can change), you should specify it specifically. > I'm fine overall with the idea of bringing the compression into the > binary using zlib, provided that we preserve the "-n" behavior > (producing reproducible archives). Thanks for voicing this concern. I had a look at zlib's source code, and it looks like it requires an extra function call (that we don't call) to make the resulting file non-reproducible. In other words, it has the opposite default behavior from `gzip`. Ciao, Dscho
