[PATCH 5/6] Makefile: use "ln -f" instead of "rm && ln"

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change the invocations and behavior of "ln-or-cp.sh" to not assume
that we're going to "rm" the file in question beforehand.

This reduces the complexity of these rules, and as a bonus means it's
now safe to "make install" on a system that may have running "git"
programs, before this we'd be racing the "rm && ln/cp" and wouldn't
have a working "git" (or one of the built-ins) in the interim.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Makefile    | 10 ++--------
 ln-or-cp.sh |  5 ++---
 2 files changed, 4 insertions(+), 11 deletions(-)

diff --git a/Makefile b/Makefile
index 29d9bade5a8..466df1a8e90 100644
--- a/Makefile
+++ b/Makefile
@@ -2204,8 +2204,7 @@ version.sp version.s version.o: EXTRA_CPPFLAGS = \
 
 $(BUILT_INS): GIT-LNCPFLAGS
 $(BUILT_INS): git$X
-	$(QUIET_BUILT_IN)$(RM) $@ && \
-	./ln-or-cp.sh \
+	$(QUIET_BUILT_IN)./ln-or-cp.sh \
 		--install-symlinks "$(INSTALL_SYMLINKS)" \
 		$< $@
 
@@ -2558,8 +2557,7 @@ git-http-push$X: http.o http-push.o GIT-LDFLAGS $(GITLIBS)
 
 $(REMOTE_CURL_ALIASES): GIT-LNCPFLAGS
 $(REMOTE_CURL_ALIASES): $(REMOTE_CURL_PRIMARY)
-	$(QUIET_LNCP)$(RM) $@ && \
-	./ln-or-cp.sh \
+	$(QUIET_LNCP)./ln-or-cp.sh \
 		--install-symlinks "$(INSTALL_SYMLINKS)" \
 		$< $@
 
@@ -3021,7 +3019,6 @@ endif
 	destdir_from_execdir_SQ=$$(echo '$(gitexecdir_relative_SQ)' | sed -e 's|[^/][^/]*|..|g') && \
 	{ test "$$bindir/" = "$$execdir/" || \
 	  for p in git$X $(filter $(install_bindir_programs),$(ALL_PROGRAMS)); do \
-		$(RM) "$$execdir/$$p" && \
 		./ln-or-cp.sh \
 			--install-symlinks "$(INSTALL_SYMLINKS)" \
 			--no-install-hardlinks "$(NO_INSTALL_HARDLINKS)" \
@@ -3031,7 +3028,6 @@ endif
 	  done; \
 	} && \
 	for p in $(filter $(install_bindir_programs),$(BUILT_INS)); do \
-		$(RM) "$$bindir/$$p" && \
 		./ln-or-cp.sh \
 			--install-symlinks "$(INSTALL_SYMLINKS)" \
 			--no-install-hardlinks "$(NO_INSTALL_HARDLINKS)" \
@@ -3039,7 +3035,6 @@ endif
 			"$$bindir/git$X" "$$bindir/$$p"; \
 	done && \
 	for p in $(BUILT_INS); do \
-		$(RM) "$$execdir/$$p" && \
 		if test -z "$(SKIP_DASHED_BUILT_INS)"; \
 		then \
 			./ln-or-cp.sh \
@@ -3051,7 +3046,6 @@ endif
 	done && \
 	remote_curl_aliases="$(REMOTE_CURL_ALIASES)" && \
 	for p in $$remote_curl_aliases; do \
-		$(RM) "$$execdir/$$p" && \
 		./ln-or-cp.sh \
 			--install-symlinks "$(INSTALL_SYMLINKS)" \
 			--no-install-hardlinks "$(NO_INSTALL_HARDLINKS)" \
diff --git a/ln-or-cp.sh b/ln-or-cp.sh
index 663ffd0489d..37380993c64 100755
--- a/ln-or-cp.sh
+++ b/ln-or-cp.sh
@@ -40,11 +40,10 @@ link="$2"
 hardlink_or_cp () {
 	if test -z "$no_install_hardlinks" -a -z "$no_cross_directory_hardlinks"
 	then
-		if ! ln "$target" "$link"
+		if ! ln -f "$target" "$link"
 		then
 			cp "$target" "$link"
 		fi
-
 	else
 		cp "$target" "$link"
 	fi
@@ -53,7 +52,7 @@ hardlink_or_cp () {
 main_with_fallbacks () {
 	if test -n "$install_symlinks" -o -n "$no_install_hardlinks"
 	then
-		if ! ln -s "$symlink_target" "$link"
+		if ! ln -f -s "$symlink_target" "$link"
 		then
 			hardlink_or_cp
 		fi
-- 
2.31.1.461.gd47399f6574