[Buildroot] [PATCH 11/18 v3] system: add support for merged /usr/sbin (aka merged-bin)
Yann E. MORIN
yann.morin.1998 at free.fr
Mon Sep 1 09:01:20 UTC 2025
Starting with version 256 [0], systemd warns when /usr/bin and
/usr/sbin are different directories; in the future, it may even
refuse to boot in such a situation.
Add support for merged-bin, not unlike the support we have for
merged-usr; we also make merged-bin a sub-case of merged-usr
(i.e. it is not possible to do merged-bin without merged-usr).
[0] https://github.com/systemd/systemd/blob/v256/NEWS#L265
Signed-off-by: Yann E. MORIN <yann.morin.1998 at free.fr>
Acked-by: Arnout Vandecappelle <arnout at mind.be>
Acked-by: TIAN Yuanhao <tianyuanhao3 at 163.com>
Cc: Edgar Bonet <bonet at grenoble.cnrs.fr>
---
Changes v1 -> v2:
- fix typo (Edgar)
---
Makefile | 1 +
package/skeleton-custom/skeleton-custom.mk | 1 +
support/scripts/check-merged | 22 +++++++++++++++++++---
system/Config.in | 11 +++++++++++
system/skeleton/usr/sbin/.empty | 0
system/system.mk | 14 +++++++++++++-
6 files changed, 45 insertions(+), 4 deletions(-)
delete mode 100644 system/skeleton/usr/sbin/.empty
diff --git a/Makefile b/Makefile
index 2ff944f6f1..5fd49c3e9b 100644
--- a/Makefile
+++ b/Makefile
@@ -785,6 +785,7 @@ endif
support/scripts/check-merged \
--type overlay \
$(if $(BR2_ROOTFS_MERGED_USR),--merged-usr) \
+ $(if $(BR2_ROOTFS_MERGED_BIN),--merged-bin) \
$(call qstrip,$(BR2_ROOTFS_OVERLAY))
$(foreach d, $(call qstrip,$(BR2_ROOTFS_OVERLAY)), \
diff --git a/package/skeleton-custom/skeleton-custom.mk b/package/skeleton-custom/skeleton-custom.mk
index 5d65b95ecf..7c79500046 100644
--- a/package/skeleton-custom/skeleton-custom.mk
+++ b/package/skeleton-custom/skeleton-custom.mk
@@ -27,6 +27,7 @@ define SKELETON_CUSTOM_CONFIGURE_CMDS
support/scripts/check-merged \
--type skeleton \
$(if $(BR2_ROOTFS_MERGED_USR),--merged-usr) \
+ $(if $(BR2_ROOTFS_MERGED_BIN),--merged-bin) \
$(SKELETON_CUSTOM_PATH)
endef
diff --git a/support/scripts/check-merged b/support/scripts/check-merged
index 3cccd68dd7..fbda49f1c0 100755
--- a/support/scripts/check-merged
+++ b/support/scripts/check-merged
@@ -1,7 +1,9 @@
#!/usr/bin/env bash
#
-# Check if a given custom skeleton or overlay complies to the merged /usr
+# Check if a given custom skeleton or overlay complies to the merged
# requirements:
+#
+# - for merged-usr:
# /bin missing, or a relative symlink to usr/bin
# /lib missing, or a relative symlink to usr/lib
# /sbin missing, or a relative symlink to usr/sbin
@@ -11,9 +13,14 @@
#
# *: must be present for skeletons, can be missing for overlays
#
+# - for merged-bin: all of the above, except:
+# /usr/sbin missing, or a relative symlink to bin (thus points
+# to /usr/bin)
+#
# Input:
# --type TYPE the type of root to check: 'skeleton' or 'overlay'
# --merged-usr check for merged /usr
+# --merged-bin check for merged /usr/bin
# $*: the root directories (skeleton, overlays) to check
# Output:
# stdout: the list of non-compliant paths (empty if compliant).
@@ -22,12 +29,13 @@
# !0: if any directory to check is improperly merged
#
-opts="type:,merged-usr"
+opts="type:,merged-usr,merged-bin"
ARGS="$(getopt -n check-merged -o "" -l "${opts}" -- "${@}")" || exit 1
eval set -- "${ARGS}"
type=
merged_usr=false
+merged_bin=false
while :; do
case "${1}" in
(--type)
@@ -38,6 +46,10 @@ while :; do
merged_usr=true
shift
;;
+ (--merged-bin)
+ merged_bin=true
+ shift
+ ;;
(--)
shift
break
@@ -110,10 +122,14 @@ for root; do
if ${merged_usr}; then
test_dir "${type}" "${root}" "/" "usr/bin"
test_dir "${type}" "${root}" "/" "usr/lib"
- test_dir "${type}" "${root}" "/" "usr/sbin"
test_merged "${type}" "${root}" "/" "bin" "usr/bin"
test_merged "${type}" "${root}" "/" "lib" "usr/lib"
test_merged "${type}" "${root}" "/" "sbin" "usr/sbin"
+ if ${merged_bin}; then
+ test_merged "${type}" "${root}" "/usr/" "sbin" "bin"
+ else
+ test_dir "${type}" "${root}" "/" "usr/sbin"
+ fi
fi
done
diff --git a/system/Config.in b/system/Config.in
index 32462241a5..0652b94a3b 100644
--- a/system/Config.in
+++ b/system/Config.in
@@ -343,6 +343,16 @@ config BR2_ROOTFS_MERGED_USR
symlinks to their counterparts in /usr. In this case, /usr can
not be a separate filesystem.
+config BR2_ROOTFS_MERGED_BIN
+ bool "Merged /usr/bin"
+ depends on BR2_ROOTFS_MERGED_USR
+ help
+ If you say 'n' here, then /usr/bin and /usr/sbin will be
+ separate directories; this is the historical UNIX way.
+
+ If you say 'y' here, then /usr/sbin will be a relative
+ symlink to /usr/bin.
+
if BR2_ROOTFS_SKELETON_DEFAULT
config BR2_TARGET_ENABLE_ROOT_LOGIN
@@ -529,6 +539,7 @@ endif # BR2_ROOTFS_SKELETON_DEFAULT
config BR2_SYSTEM_DEFAULT_PATH
string "Set the system's default PATH"
+ default "/usr/bin" if BR2_ROOTFS_MERGED_BIN
default "/usr/bin:/usr/sbin" if BR2_ROOTFS_MERGED_USR
default "/bin:/sbin:/usr/bin:/usr/sbin"
help
diff --git a/system/skeleton/usr/sbin/.empty b/system/skeleton/usr/sbin/.empty
deleted file mode 100644
index e69de29bb2..0000000000
diff --git a/system/system.mk b/system/system.mk
index 8fe2c138b0..52e810868a 100644
--- a/system/system.mk
+++ b/system/system.mk
@@ -32,18 +32,30 @@
# set inittab to remount root read-write or read-only
#
-# This function handles the merged or non-merged /usr cases
+# This function handles the merged or non-merged /usr, and merged or
+# non-merged /usr/bin cases
ifeq ($(BR2_ROOTFS_MERGED_USR),y)
+ifeq ($(BR2_ROOTFS_MERGED_BIN),y)
+define SYSTEM_SBIN_SYMLINKS_OR_DIRS
+ ln -snf bin $(1)/usr/sbin
+endef
+else
+define SYSTEM_SBIN_SYMLINKS_OR_DIRS
+ $(INSTALL) -d -m 0755 $(1)/usr/sbin
+endef
+endif
define SYSTEM_USR_SYMLINKS_OR_DIRS
ln -snf usr/bin $(1)/bin
ln -snf usr/sbin $(1)/sbin
ln -snf usr/lib $(1)/lib
+ $(SYSTEM_SBIN_SYMLINKS_OR_DIRS)
endef
else
define SYSTEM_USR_SYMLINKS_OR_DIRS
$(INSTALL) -d -m 0755 $(1)/bin
$(INSTALL) -d -m 0755 $(1)/sbin
$(INSTALL) -d -m 0755 $(1)/lib
+ $(INSTALL) -d -m 0755 $(1)/usr/sbin
endef
endif
--
2.51.0
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