[RFC/PATCH 4/5] Makefile: add NO_INSTALL_SYMLINKS_FALLBACK switch

From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: git@vger.kernel.org
Cc: "Junio C Hamano" <gitster@pobox.com>,
	"Daniel Jacques" <dnj@google.com>,
	"Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
	"Steffen Prohaska" <prohaska@zib.de>,
	"John Keeping" <john@keeping.me.uk>, "Stan Hu" <stanhu@gmail.com>,
	"Richard Clamp" <richardc@unixbeard.net>,
	"Jeff King" <peff@peff.net>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: [RFC/PATCH 4/5] Makefile: add NO_INSTALL_SYMLINKS_FALLBACK switch
Date: Fri,  2 Nov 2018 22:37:42 +0000	[thread overview]
Message-ID: <20181102223743.4331-5-avarab@gmail.com> (raw)
In-Reply-To: <87efkkdwcv.fsf@evledraar.gmail.com>

Add a switch for use in conjunction with the INSTALL_SYMLINKS flag
added in ad874608d8 ("Makefile: optionally symlink libexec/git-core
binaries to bin/git", 2018-03-13).

Now it's possible to install git with:

    INSTALL_SYMLINKS=YesPlease NO_INSTALL_SYMLINKS_FALLBACK=YesPlease

And know for sure that there's not going to be any silent fallbacks on
hardlinks or copying of files if symlinking fails.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Makefile         |  5 ++++
 install_programs | 69 ++++++++++++++++++++++++++++++++----------------
 2 files changed, 51 insertions(+), 23 deletions(-)

diff --git a/Makefile b/Makefile
index aa6ca1fa68..07c8b74353 100644
--- a/Makefile
+++ b/Makefile
@@ -342,6 +342,10 @@ all::
 # within the same directory in some cases, INSTALL_SYMLINKS will
 # always symlink to the final target directly.
 #
+# Define NO_INSTALL_SYMLINKS_FALLBACK if in conjunction with
+# INSTALL_SYMLINKS if you'd prefer not to have the install procedure
+# fallack on hardlinking or copying if "ln -s" fails.
+#
 # Define NO_CROSS_DIRECTORY_HARDLINKS if you plan to distribute the installed
 # programs as a tar, where bin/ and libexec/ might be on different file systems.
 #
@@ -2818,6 +2822,7 @@ endif
 		--flag-install-symlinks="$(INSTALL_SYMLINKS)" \
 		--flag-no-install-hardlinks="$(NO_INSTALL_HARDLINKS)" \
 		--flag-no-cross-directory-hardlinks="$(NO_CROSS_DIRECTORY_HARDLINKS)" \
+		--flag-no-install-symlinks-fallback="$(NO_INSTALL_SYMLINKS_FALLBACK)" \
 		--list-bindir-standalone="git$X $(filter $(install_bindir_programs),$(ALL_PROGRAMS))" \
 		--list-bindir-git-dashed="$(filter $(install_bindir_programs),$(BUILT_INS))" \
 		--list-execdir-git-dashed="$(BUILT_INS)" \
diff --git a/install_programs b/install_programs
index 367e9a6cdf..51e08019dd 100755
--- a/install_programs
+++ b/install_programs
@@ -30,6 +30,9 @@ do
 	--flag-no-cross-directory-hardlinks=*)
 		NO_CROSS_DIRECTORY_HARDLINKS="${1#--flag-no-cross-directory-hardlinks=}"
 		;;
+	--flag-no-install-symlinks-fallback=*)
+		NO_INSTALL_SYMLINKS_FALLBACK="${1#--flag-no-install-symlinks-fallback=}"
+		;;
 	--list-bindir-standalone=*)
 		list_bindir_standalone="${1#--list-bindir-standalone=}"
 		;;
@@ -55,41 +58,61 @@ if test "$bindir/" != "$execdir/"
 then
 	for p in $list_bindir_standalone; do
 		$RM "$execdir/$p" &&
-		test -n "$INSTALL_SYMLINKS" &&
-		ln -s "$destdir_from_execdir/$bindir_relative/$p" "$execdir/$p" ||
-		{ test -z "$NO_INSTALL_HARDLINKS$NO_CROSS_DIRECTORY_HARDLINKS" &&
-		  ln "$bindir/$p" "$execdir/$p" ||
-		  cp "$bindir/$p" "$execdir/$p" || exit; }
+		if test -n "$INSTALL_SYMLINKS" -a -n "$NO_INSTALL_SYMLINKS_FALLBACK"
+		then
+			ln -s "$destdir_from_execdir/$bindir_relative/$p" "$execdir/$p"
+		else
+			test -n "$INSTALL_SYMLINKS" &&
+			ln -s "$destdir_from_execdir/$bindir_relative/$p" "$execdir/$p" ||
+			{ test -z "$NO_INSTALL_HARDLINKS$NO_CROSS_DIRECTORY_HARDLINKS" &&
+			  ln "$bindir/$p" "$execdir/$p" ||
+			  cp "$bindir/$p" "$execdir/$p" || exit; }
+		fi
 	done
 fi &&
 
 for p in $list_bindir_git_dashed
 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" ||
-	  ln -s "git$X" "$bindir/$p" ||
-	  cp "$bindir/git$X" "$bindir/$p" || exit; }
+	if test -n "$INSTALL_SYMLINKS" -a -n "$NO_INSTALL_SYMLINKS_FALLBACK"
+	then
+		ln -s "git$X" "$bindir/$p"
+	else
+		test -n "$INSTALL_SYMLINKS" &&
+		ln -s "git$X" "$bindir/$p" ||
+		{ test -z "$NO_INSTALL_HARDLINKS" &&
+		  ln "$bindir/git$X" "$bindir/$p" ||
+		  ln -s "git$X" "$bindir/$p" ||
+		  cp "$bindir/git$X" "$bindir/$p" || exit; }
+	fi
 done &&
 
 for p in $list_execdir_git_dashed; do
 	$RM "$execdir/$p" &&
-	test -n "$INSTALL_SYMLINKS" &&
-	ln -s "$destdir_from_execdir/$bindir_relative/git$X" "$execdir/$p" ||
-	{ test -z "$NO_INSTALL_HARDLINKS" &&
-	  ln "$execdir/git$X" "$execdir/$p" ||
-	  ln -s "git$X" "$execdir/$p" ||
-	  cp "$execdir/git$X" "$execdir/$p" || exit; }
+	if test -n "$INSTALL_SYMLINKS" -a -n "$NO_INSTALL_SYMLINKS_FALLBACK"
+	then
+		ln -s "$destdir_from_execdir/$bindir_relative/git$X" "$execdir/$p"
+	else
+		test -n "$INSTALL_SYMLINKS" &&
+		ln -s "$destdir_from_execdir/$bindir_relative/git$X" "$execdir/$p" ||
+		{ test -z "$NO_INSTALL_HARDLINKS" &&
+		  ln "$execdir/git$X" "$execdir/$p" ||
+		  ln -s "git$X" "$execdir/$p" ||
+		  cp "$execdir/git$X" "$execdir/$p" || exit; }
+	fi
 done &&
 
 for p in $list_execdir_curl_aliases; do
 	$RM "$execdir/$p" &&
-	test -n "$INSTALL_SYMLINKS" &&
-	ln -s "git-remote-http$X" "$execdir/$p" ||
-	{ test -z "$NO_INSTALL_HARDLINKS" &&
-	  ln "$execdir/git-remote-http$X" "$execdir/$p" ||
-	  ln -s "git-remote-http$X" "$execdir/$p" ||
-	  cp "$execdir/git-remote-http$X" "$execdir/$p" || exit; }
+	if test -n "$INSTALL_SYMLINKS" -a -n "$NO_INSTALL_SYMLINKS_FALLBACK"
+	then
+		ln -s "git-remote-http$X" "$execdir/$p"
+	else
+		test -n "$INSTALL_SYMLINKS" &&
+		ln -s "git-remote-http$X" "$execdir/$p" ||
+		{ test -z "$NO_INSTALL_HARDLINKS" &&
+		  ln "$execdir/git-remote-http$X" "$execdir/$p" ||
+		  ln -s "git-remote-http$X" "$execdir/$p" ||
+		  cp "$execdir/git-remote-http$X" "$execdir/$p" || exit; }
+	fi
 done
-- 
2.19.1.930.g4563a0d9d0

