From: "Đoàn Trần Công Danh" <congdanhqx@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Eric Sunshine <sunshine@sunshineco.com>,
Alexander Ost <ost@ieee.org>, Git List <git@vger.kernel.org>
Subject: Re: [BUG] `make install' partly ignores `NO_INSTALL_HARDLINKS'
Date: Tue, 18 Aug 2020 00:06:07 +0700 [thread overview]
Message-ID: <20200817170607.GA16630@danh.dev> (raw)
In-Reply-To: <xmqq8sed445k.fsf@gitster.c.googlers.com>
On 2020-08-17 09:40:23-0700, Junio C Hamano <gitster@pobox.com> wrote:
> Đoàn Trần Công Danh <congdanhqx@gmail.com> writes:
>
> > On 2020-08-14 10:26:24-0700, Junio C Hamano <gitster@pobox.com> wrote:
> >> > Since both git-citool and git-gui will be installed into same
> >> > directory "$(libexecdir)", I think it would make more sense to use:
> >> >
> >> > LN = ln -s
> >> >
> >> > here instead?
> >>
> >> In the top-level Makefile, INSTALL_SYMLINKS make macro does exist,
> >> but it is not exported to submakes. If it were, something like
> >>
> >> ifdef INSTALL_SYMLINKS
> >> LN = ln -s
> >> else
> >> ifdef NO_INSTALL_HARDLINKS
> >> LN = cp
> >> else
> >> LN = ln
> >> endif
> >> endif
> >>
> >> might become possible, but you'd need to audit what is fed to $(LN)
> >> at the locations the macro is used and make necessary adjustment
> >> accordingly. "cp A ../B" or "ln A ../B" will make a usable copy of
> >> file A appear inside ../B directory, but "ln -s A ../B" will not,
> >> and I didn't see if all uses of $(LN) was to give synonyms to what
> >> is already installed, or some of them were truly installing from the
> >> build location when I gave the "something along this line" example.
> >
> > Yes, the top-level Makefile seems to have a special branch for
> > BUILT_INS, in which, we will create symlink for those builtin in
> > libexecdr if NO_INSTALL_HARDLINKS is defined.
>
> Did you mean pieces like this?
>
> for p in $(filter $(install_bindir_programs),$(BUILT_INS)); do \
> $(RM) "$$bindir/$$p" && \
> test -n "$(INSTALL_SYMLINKS)" && \
> ln -s "git$X" "$$bindir/$$p" || \
> { test -z "$(NO_INSTALL_HARDLINKS)" && \
> ln "$$bindir/git$X" "$$bindir/$$p" 2>/dev/null || \
> ln -s "git$X" "$$bindir/$$p" 2>/dev/null || \
> cp "$$bindir/git$X" "$$bindir/$$p" || exit; } \
> done && \
Yes, I meant this piece.
> The symlinks happen ONLY when INSTALL_SYMLINKS is asked for.
Not what I understand from that code.
When `INSTALL_SYMLINKS` is not asked, the shell will jump to this block:
{ test -z "$(NO_INSTALL_HARDLINKS)" && \
ln "$$bindir/git$X" "$$bindir/$$p" 2>/dev/null || \
ln -s "git$X" "$$bindir/$$p" 2>/dev/null || \
cp "$$bindir/git$X" "$$bindir/$$p" || exit; } \
When NO_INSTALL_HARDLINKS is asked, the shell will jump to last
2 clauses:
ln -s "git$X" "$$bindir/$$p" 2>/dev/null || \
cp "$$bindir/git$X" "$$bindir/$$p" || exit; } \
shell try to "ln -s" first, when it failed to symlink, cp will be used.
In fact, this's what we used for packaging in distro, we often ask for:
NO_INSTALL_HARDLINKS
> Not all filesystems support symbolic links,
This is correct, but most sane package manager will do the right thing.
> hardlinks never suffer from
> dangling link problem, and often they are cheaper.
Part of the reason we don't ask for INSTALL_SYMLINKS,
because with INSTALL_SYMLINKS, symlink will be make from
$(libexecdir)/git to $(bindir)/git.
But, NO_INSTALL_HARDLINKS will only symlink inside $(libexecdir), e.g:
$ ls -al $(/usr/bin/git --exec-path )/git
-rwxr-xr-x 1 root root 3193704 2020-08-12 21:37 /usr/libexec/git-core/git
$ ls -al $(/usr/bin/git --exec-path )/git-ls-files
lrwxrwxrwx 1 root root 3 2020-08-12 21:37 /usr/libexec/git-core/git-ls-files -> git
And those symlinks are packaged and managed by package manager,
so, no, no dangling problem.
--
Danh
prev parent reply other threads:[~2020-08-17 17:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-12 8:15 [BUG] `make install' partly ignores `NO_INSTALL_HARDLINKS' Alexander Ost
2020-08-13 21:45 ` Eric Sunshine
2020-08-13 21:52 ` Junio C Hamano
2020-08-14 8:33 ` Alexander Ost
2020-08-14 15:02 ` Đoàn Trần Công Danh
2020-08-14 17:26 ` Junio C Hamano
2020-08-15 1:15 ` Đoàn Trần Công Danh
2020-08-17 16:40 ` Junio C Hamano
2020-08-17 17:06 ` Đoàn Trần Công Danh [this message]
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