libarchive formula omits LZMA support

[dsoprea]

Is there a reason for the "--without-lzma" switch (like a lack of library support under Mac)? I need LZMA (7-Zip).

    system "./configure", "--prefix=#{prefix}",
                          "--without-lzma",
                          "--without-lzo2",
                          "--without-nettle",
                          "--without-xml2"

[mistydemeo]

At a guess, it's just because it would a) add an extra dependency, b) it hasn't been requested yet. We could add an option!

I tried removing the flag, and it didn't build with lzma anyway since liblzma wasn't available:

checking lzmadec.h usability... no
checking lzmadec.h presence... no
checking for lzmadec.h... no
checking for lzmadec_decode in -llzmadec... no

[mistydemeo]

It looks like we provide lzma via the xz formula, but it doesn't include the lzmadec.h header or a liblzmadec.

[dsoprea]

It does:

libarchive/libarchive$ grep lzma -R . | grep "\.h"
./archive.h:__LA_DECL int archive_read_support_compression_lzma(struct
archive *)
./archive.h:__LA_DECL int archive_read_support_filter_lzma(struct archive
*);
./archive.h:__LA_DECL int archive_write_set_compression_lzma(struct archive
*)
./archive.h:__LA_DECL int archive_write_add_filter_lzma(struct archive *);
./archive_read_support_filter_xz.c:#include <lzma.h>
./archive_read_support_filter_xz.c:#include <lzmadec.h>
./archive_read_support_format_7zip.c:#include <lzma.h>
./archive_read_support_format_xar.c:#include <lzma.h>
./archive_read_support_format_xar.c:#include <lzmadec.h>
./archive_util.c:#include <lzma.h>
./archive_write_add_filter_xz.c:#include <lzma.h>
./archive_write_set_format_7zip.c:#include <lzma.h>
./archive_write_set_format_xar.c:#include <lzma.h>

On the contrary, I would assume that we wouldn't arbitrarily pare-down the
builds... That we'd let them build with its defaults unless there are
something explicitly requested. That way, it's relatively compatible to
what's there when building from the source directly or installing a package
on a platform (like Ubuntu).

Either way, can't we just add the xz formula as a dependency? I've had to
work on one project in a terminal to Ubuntu, and am currently building the
source to try to get something local.

On Thu, Apr 17, 2014 at 2:06 PM, Misty De Meo notifications@github.comwrote:

It looks like we provide lzma via the xz formula, but it doesn't include
the lzmadec.h header or a liblzmadec.

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[mistydemeo]

Ignore that last comment.

[mistydemeo]

Missed the part later in the configure script where it looks for them - yep, does seem to find them via xz.

[mistydemeo]

depends_on 'xz' => :optional and removing --disable-lzma from the configure switch is enough to make this work.

[dsoprea]

Would LZMA access cause an unresolvable binding if xz isn't installed?

On Thu, Apr 17, 2014 at 2:21 PM, Misty De Meo notifications@github.comwrote:

depends_on 'xz' => :optional and removing --disable-lzma from the
configure switch is enough to make this work.

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[mistydemeo]

xz would be a dependency, so you'd need to installed to build libarchive with lzma, and if you removed xz then libarchive wouldn't work. (Same as any other dependency.)

[dsoprea]

I'm not familiar with the Homebrew formula declarative. There's no way to
configure one way if an optional dependency is satisfied or another if not?

On Thu, Apr 17, 2014 at 2:41 PM, Misty De Meo notifications@github.comwrote:

xz would be a dependency, so you'd need to installed to build libarchive
with lzma, and if you removed xz then libarchive wouldn't work. (Same as
any other dependency.)

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[mistydemeo]

Homebrew doesn't opportunistically pick up dependencies; it's on if requested, and off otherwise. (Since Homebrew also isolates the build environment, it means xz will not be visible if not requested, even if installed.)

[dsoprea]

Okay. Can you go ahead and make the update?

On Thu, Apr 17, 2014 at 2:58 PM, Misty De Meo notifications@github.comwrote:

Homebrew doesn't opportunistically pick up dependencies; it's on if
requested, and off otherwise. (Since Homebrew also isolates the build
environment, it means xz will not be visible if not requested, even if
installed.)

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