[openwrt/openwrt] build: fix opkg install step for large package selection

[LEDE Commits]

aparcar pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/1854aeec4d37079690309dec3171d0864339f73a

commit 1854aeec4d37079690309dec3171d0864339f73a
Author: Alexander Egorenkov <egorenar-dev at posteo.net>
AuthorDate: Sat Apr 10 01:32:44 2021 +0200

    build: fix opkg install step for large package selection
    
    When the list of packages to be installed in a built image exceeds a certain
    number, then 'opkg install' executed for target '$(curdir)/install' in
    package/Makefile fails with: /usr/bin/env: Argument list too long.
    
    On Linux, the length of a command-line parameter is limited by
    MAX_ARG_STRLEN to max 128 kB.
    
    * https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/binfmts.h#L15
    * https://www.in-ulm.de/~mascheck/various/argmax/
    
    To solve the problem, store the package list being passed to 'opkg install'
    in a temporary file and use the shell command substitution to pass the
    content of the file to 'opkg install'. This guarantees that the length of
    the command-line parameters passed to the bash shell is short.
    
    The following bash script demonstrates the problem:
    ----------------------------------------------------------------------------
    count=${1:-1000}
    
    FILES=""
    a_file="/home/egorenar/Repositories/openwrt-rel/bin/targets/alpine/generic/packages/base-files_1414-r16464+19-e887049fbb_arm_cortex-a15_neon-vfpv4.ipk"
    
    for i in $(seq 1 $count); do
            FILES="$FILES $a_file"
    done
    
    env bash -c "echo $FILES >/dev/null"
    echo "$FILES" | wc -c
    ----------------------------------------------------------------------------
    
    Test run:
    ----------------------------------------------------------------------------
    $ ./test.sh 916
    130989
    $ ./test.sh 917
    ./test.sh: line 14: /bin/env: Argument list too long
    131132
    ----------------------------------------------------------------------------
    
    Signed-off-by: Alexander Egorenkov <egorenar-dev at posteo.net>
    [reword commit subject]
    Signed-off-by: Paul Spooren <mail at aparcar.org>
---
 package/Makefile | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/package/Makefile b/package/Makefile
index ec503dc527..209be34674 100644
--- a/package/Makefile
+++ b/package/Makefile
@@ -66,8 +66,10 @@ $(curdir)/install: $(TMP_DIR)/.build $(curdir)/merge $(if $(CONFIG_TARGET_PER_DE
 	- find $(STAGING_DIR_ROOT) -type d | $(XARGS) chmod 0755
 	rm -rf $(TARGET_DIR) $(TARGET_DIR_ORIG)
 	mkdir -p $(TARGET_DIR)/tmp
-	$(call opkg,$(TARGET_DIR)) install \
-		$(call opkg_package_files,$(foreach pkg,$(shell cat $(PACKAGE_INSTALL_FILES) 2>/dev/null),$(pkg)$(call GetABISuffix,$(pkg))))
+	$(file >$(TMP_DIR)/opkg_install_list,\
+	  $(call opkg_package_files,\
+	    $(foreach pkg,$(shell cat $(PACKAGE_INSTALL_FILES) 2>/dev/null),$(pkg)$(call GetABISuffix,$(pkg)))))
+	$(call opkg,$(TARGET_DIR)) install $$(cat $(TMP_DIR)/opkg_install_list)
 	@for file in $(PACKAGE_INSTALL_FILES); do \
 		[ -s $$file.flags ] || continue; \
 		for flag in `cat $$file.flags`; do \