[v2,2/3] Optionally skip linking/copying the built-ins

Commit Message

Linus Arver via GitGitGadget Aug. 24, 2020, 3:37 p.m. UTC

From: Johannes Schindelin <[e-mail]>

For a long time already, the non-dashed form of the built-ins is the
recommended way to write scripts, i.e. it is better to call `git merge
[...]` than to call `git-merge [...]`.

While Git still supports the dashed form (by hard-linking the `git`
executable to the dashed name in `libexec/git-core/`), in practice, it
is probably almost irrelevant.

In fact, some platforms (such as Windows) only started gaining
meaningful Git support _after_ the dashed form was deprecated, and
therefore one would expect that all this hard-linking is unnecessary on
those platforms.

In addition to that, some programs that are regularly used to assess
disk usage fail to realize that those are hard-links, and heavily
overcount disk usage. Most notably, this was the case with Windows
Explorer up until the last couple of Windows 10 versions.

To save on the time needed to hard-link these dashed commands, and to
eventually stop shipping with those hard-links on Windows, let's
introduce a Makefile knob to skip generating them.

Signed-off-by: Johannes Schindelin <[e-mail]>
---
 Makefile | 55 +++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 37 insertions(+), 18 deletions(-)

Comments

Junio C Hamano Aug. 24, 2020, 7:02 p.m. UTC | #1

"Johannes Schindelin via GitGitGadget" <[e-mail]>
writes:

> While Git still supports the dashed form (by hard-linking the `git`
> executable to the dashed name in `libexec/git-core/`), in practice, it
> is probably almost irrelevant.

It is irrelevant when you have to say "probably" without facts, and
this paragraph is not necessary to justify this option.  I'd omit it.

We do care about keeping people's scripts working (even if they were
written before Windows folks started using Git---those people who
started using Git before that still exist ;-).

> In fact, some platforms (such as Windows) only started gaining
> meaningful Git support _after_ the dashed form was deprecated, and
> therefore one would expect that all this hard-linking is unnecessary on
> those platforms.
> 
> In addition to that, some programs that are regularly used to assess
> disk usage fail to realize that those are hard-links, and heavily
> overcount disk usage. Most notably, this was the case with Windows
> Explorer up until the last couple of Windows 10 versions.

However, the above two paragraphs I would suggest to keep, as they
do matter---it is a good justification to have this configurable.
Windows folks won't be able to copy and use POSIX shell scripts
written by folks before the Windows port of Git was started to
become widely used anyway.

Johannes Schindelin Aug. 25, 2020, 8:20 a.m. UTC | #2

Hi Junio,

On Mon, 24 Aug 2020, Junio C Hamano wrote:

> "Johannes Schindelin via GitGitGadget" <[e-mail]>
> writes:
>
> > While Git still supports the dashed form (by hard-linking the `git`
> > executable to the dashed name in `libexec/git-core/`), in practice, it
> > is probably almost irrelevant.
>
> It is irrelevant when you have to say "probably" without facts, and
> this paragraph is not necessary to justify this option.  I'd omit it.

I would like to gently request to keep the sentence in, as it will provide
me with the context when I stumble across this commit the next time.

> We do care about keeping people's scripts working (even if they were
> written before Windows folks started using Git---those people who
> started using Git before that still exist ;-).

That, however, I totally understand, and I think you're right, I should
add this sentence (in one form or another).

> > In fact, some platforms (such as Windows) only started gaining
> > meaningful Git support _after_ the dashed form was deprecated, and
> > therefore one would expect that all this hard-linking is unnecessary on
> > those platforms.
> >
> > In addition to that, some programs that are regularly used to assess
> > disk usage fail to realize that those are hard-links, and heavily
> > overcount disk usage. Most notably, this was the case with Windows
> > Explorer up until the last couple of Windows 10 versions.
>
> However, the above two paragraphs I would suggest to keep, as they
> do matter---it is a good justification to have this configurable.
> Windows folks won't be able to copy and use POSIX shell scripts
> written by folks before the Windows port of Git was started to
> become widely used anyway.

Excellent!

Ciao,
Dscho

Patch

diff --git a/Makefile b/Makefile
index 66b6e076e2..0a09146fb3 100644
--- a/Makefile
+++ b/Makefile
@@ -348,6 +348,9 @@  all::
 # Define NO_INSTALL_HARDLINKS if you prefer to use either symbolic links or
 # copies to install built-in git commands e.g. git-cat-file.
 #
+# Define SKIP_DASHED_BUILT_INS if you do not need the dashed versions of the
+# built-ins to be linked/copied at all.
+#
 # Define USE_NED_ALLOCATOR if you want to replace the platforms default
 # memory allocators with the nedmalloc allocator written by Niall Douglas.
 #
@@ -775,6 +778,16 @@  BUILT_INS += git-whatchanged$X
 # what 'all' will build and 'install' will install in gitexecdir,
 # excluding programs for built-in commands
 ALL_PROGRAMS = $(PROGRAMS) $(SCRIPTS)
+ALL_COMMANDS_TO_INSTALL = $(ALL_PROGRAMS)
+ifeq (,$(SKIP_DASHED_BUILT_INS))
+ALL_COMMANDS_TO_INSTALL += $(BUILT_INS)
+else
+# git-upload-pack, git-receive-pack and git-upload-archive are special: they
+# are _expected_ to be present in the `bin/` directory in their dashed form.
+ALL_COMMANDS_TO_INSTALL += git-receive-pack$(X)
+ALL_COMMANDS_TO_INSTALL += git-upload-archive$(X)
+ALL_COMMANDS_TO_INSTALL += git-upload-pack$(X)
+endif
 
 # what 'all' will build but not install in gitexecdir
 OTHER_PROGRAMS = git$X
@@ -2066,9 +2079,9 @@  profile-fast: profile-clean
 	$(MAKE) PROFILE=USE all
 
 
-all:: $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS) $(OTHER_PROGRAMS) GIT-BUILD-OPTIONS
+all:: $(ALL_COMMANDS_TO_INSTALL) $(SCRIPT_LIB) $(OTHER_PROGRAMS) GIT-BUILD-OPTIONS
 ifneq (,$X)
-	$(QUIET_BUILT_IN)$(foreach p,$(patsubst %$X,%,$(filter %$X,$(ALL_PROGRAMS) $(BUILT_INS) git$X)), test -d '$p' -o '$p' -ef '$p$X' || $(RM) '$p';)
+	$(QUIET_BUILT_IN)$(foreach p,$(patsubst %$X,%,$(filter %$X,$(ALL_COMMANDS_TO_INSTALL) git$X)), test -d '$p' -o '$p' -ef '$p$X' || $(RM) '$p';)
 endif
 
 all::
@@ -2928,7 +2941,7 @@  ifndef NO_TCLTK
 	$(MAKE) -C git-gui gitexecdir='$(gitexec_instdir_SQ)' install
 endif
 ifneq (,$X)
-	$(foreach p,$(patsubst %$X,%,$(filter %$X,$(ALL_PROGRAMS) $(BUILT_INS) git$X)), test '$(DESTDIR_SQ)$(gitexec_instdir_SQ)/$p' -ef '$(DESTDIR_SQ)$(gitexec_instdir_SQ)/$p$X' || $(RM) '$(DESTDIR_SQ)$(gitexec_instdir_SQ)/$p';)
+	$(foreach p,$(patsubst %$X,%,$(filter %$X,$(ALL_COMMANDS_TO_INSTALL) git$X)), test '$(DESTDIR_SQ)$(gitexec_instdir_SQ)/$p' -ef '$(DESTDIR_SQ)$(gitexec_instdir_SQ)/$p$X' || $(RM) '$(DESTDIR_SQ)$(gitexec_instdir_SQ)/$p';)
 endif
 
 	bindir=$$(cd '$(DESTDIR_SQ)$(bindir_SQ)' && pwd) && \
@@ -2946,21 +2959,27 @@  endif
 	} && \
 	for p in $(filter $(install_bindir_programs),$(BUILT_INS)); do \
 		$(RM) "$$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/$$p" || exit; } \
+		if test -z "$(SKIP_DASHED_BUILT_INS)"; \
+		then \
+			test -n "$(INSTALL_SYMLINKS)" && \
+			ln -s "git$X" "$$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/$$p" || exit; }; \
+		fi \
 	done && \
 	for p in $(BUILT_INS); do \
 		$(RM) "$$execdir/$$p" && \
-		test -n "$(INSTALL_SYMLINKS)" && \
-		ln -s "$$destdir_from_execdir_SQ/$(bindir_relative_SQ)/git$X" "$$execdir/$$p" || \
-		{ test -z "$(NO_INSTALL_HARDLINKS)" && \
-		  ln "$$execdir/git$X" "$$execdir/$$p" 2>/dev/null || \
-		  ln -s "git$X" "$$execdir/$$p" 2>/dev/null || \
-		  cp "$$execdir/git$X" "$$execdir/$$p" || exit; } \
+		if test -z "$(SKIP_DASHED_BUILT_INS)"; \
+		then \
+			test -n "$(INSTALL_SYMLINKS)" && \
+			ln -s "$$destdir_from_execdir_SQ/$(bindir_relative_SQ)/git$X" "$$execdir/$$p" || \
+			{ test -z "$(NO_INSTALL_HARDLINKS)" && \
+			  ln "$$execdir/git$X" "$$execdir/$$p" 2>/dev/null || \
+			  ln -s "git$X" "$$execdir/$$p" 2>/dev/null || \
+			  cp "$$execdir/git$X" "$$execdir/$$p" || exit; }; \
+		fi \
 	done && \
 	remote_curl_aliases="$(REMOTE_CURL_ALIASES)" && \
 	for p in $$remote_curl_aliases; do \
@@ -3051,7 +3070,7 @@  ifneq ($(INCLUDE_DLLS_IN_ARTIFACTS),)
 OTHER_PROGRAMS += $(shell echo *.dll t/helper/*.dll)
 endif
 
-artifacts-tar:: $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS) $(OTHER_PROGRAMS) \
+artifacts-tar:: $(ALL_COMMANDS_TO_INSTALL) $(SCRIPT_LIB) $(OTHER_PROGRAMS) \
 		GIT-BUILD-OPTIONS $(TEST_PROGRAMS) $(test_bindir_programs) \
 		$(MOFILES)
 	$(QUIET_SUBDIR0)templates $(QUIET_SUBDIR1) \
@@ -3146,7 +3165,7 @@  endif
 
 ### Check documentation
 #
-ALL_COMMANDS = $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS)
+ALL_COMMANDS = $(ALL_COMMANDS_TO_INSTALL) $(SCRIPT_LIB)
 ALL_COMMANDS += git
 ALL_COMMANDS += git-citool
 ALL_COMMANDS += git-gui
@@ -3186,7 +3205,7 @@  check-docs::
 		    -e 's/\.txt//'; \
 	) | while read how cmd; \
 	do \
-		case " $(patsubst %$X,%,$(ALL_COMMANDS) $(EXCLUDED_PROGRAMS)) " in \
+		case " $(patsubst %$X,%,$(ALL_COMMANDS) $(BUILT_INS) $(EXCLUDED_PROGRAMS)) " in \
 		*" $$cmd "*)	;; \
 		*) echo "removed but $$how: $$cmd" ;; \
 		esac; \