[openwrt/openwrt] prereq-build: allow host command symlinks to update

[LEDE Commits]

ynezz pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/f75204036ccc56700df18258602cc65726dd653b

commit f75204036ccc56700df18258602cc65726dd653b
Author: Michael Pratt <mcpratt at pm.me>
AuthorDate: Sun May 22 06:10:56 2022 -0400

    prereq-build: allow host command symlinks to update
    
    This makes the prereq stage update the symlinks
    installed into staging_dir/host/bin
    by rearrainging the way they are verified.
    
    Before, seeing or installing a symlink would result in
    a successful exit code, and not installing a symlink
    would result is a failed exit code. However,
    that is not able to account for the difference
    between existing good and bad links, or whether
    the link would be the same if it was reinstalled,
    because the check can match the program to a different path.
    
    Instead, let a success exit code represent
    identifying an existing symlink as exactly the same
    as what would be installed if it did not exist,
    and let a fail exit code represent
    needing to install the symlink
    or not having a match to the check criteria.
    
    The failing exit code is caught by a new second attempt
    for all of the check-* targets which will then indicate
    to the user that there was an update by having a success
    exit code when the check is run again and the link is the same.
    
    When there is nothing to update, the checks will run only once.
    
    This relies on the ls command to be POSIX-conformant with long format:
    "path/to/link -> target/of/link"
    
    Also, make sure the symlink is executable, not just a file,
    and the directory only needs to be created once.
    
    Fixes: #12610
    Signed-off-by: Michael Pratt <mcpratt at pm.me>
---
 include/prereq.mk | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/prereq.mk b/include/prereq.mk
index d34539ec30..89660d323d 100644
--- a/include/prereq.mk
+++ b/include/prereq.mk
@@ -30,6 +30,8 @@ define Require
 		printf "Checking '$(1)'... "
 		if $(NO_TRACE_MAKE) -f $(firstword $(MAKEFILE_LIST)) check-$(1) >/dev/null 2>/dev/null; then \
 			echo 'ok.'; \
+		elif $(NO_TRACE_MAKE) -f $(firstword $(MAKEFILE_LIST)) check-$(1) >/dev/null 2>/dev/null; then \
+			echo 'updated.'; \
 		else \
 			echo 'failed.'; \
 			echo "$(PKG_NAME): $(strip $(2))" >> $(TMP_DIR)/.prereq-error; \
@@ -107,7 +109,7 @@ endef
 # 3+: candidates
 define SetupHostCommand
   define Require/$(1)
-	[ -f "$(STAGING_DIR_HOST)/bin/$(strip $(1))" ] && exit 0; \
+	mkdir -p "$(STAGING_DIR_HOST)/bin"; \
 	for cmd in $(call QuoteHostCommand,$(3)) $(call QuoteHostCommand,$(4)) \
 	           $(call QuoteHostCommand,$(5)) $(call QuoteHostCommand,$(6)) \
 	           $(call QuoteHostCommand,$(7)) $(call QuoteHostCommand,$(8)) \
@@ -117,9 +119,13 @@ define SetupHostCommand
 			bin="$$$$$$$$(PATH="$(subst $(space),:,$(filter-out $(STAGING_DIR_HOST)/%,$(subst :,$(space),$(PATH))))" \
 				command -v "$$$$$$$${cmd%% *}")"; \
 			if [ -x "$$$$$$$$bin" ] && eval "$$$$$$$$cmd" >/dev/null 2>/dev/null; then \
-				mkdir -p "$(STAGING_DIR_HOST)/bin"; \
+				case "$$$$$$$$(ls -dl -- $(STAGING_DIR_HOST)/bin/$(strip $(1)))" in \
+					*" -> $$$$$$$$bin"*) \
+						[ -x "$(STAGING_DIR_HOST)/bin/$(strip $(1))" ] && exit 0 \
+						;; \
+				esac; \
 				ln -sf "$$$$$$$$bin" "$(STAGING_DIR_HOST)/bin/$(strip $(1))"; \
-				exit 0; \
+				exit 1; \
 			fi; \
 		fi; \
 	done; \