[source] base-files: fix getting gid from group_add_next

[LEDE Commits]

yousong pushed a commit to source.git, branch master:
https://git.lede-project.org/b2aa820b48add74b97e0eab993ede648c43e85db

commit b2aa820b48add74b97e0eab993ede648c43e85db
Author: Yousong Zhou <yszhou4tech at gmail.com>
AuthorDate: Thu Nov 9 17:29:56 2017 +0800

    base-files: fix getting gid from group_add_next
    
    Shell function return code only has range [0, 255].  Other values will
    be truncated, e.g. return 65536 will have the same effect as return 0
    
    While at it, drop other "return $rc" where rc will almost always take
    value 0 and whose value current callers actually do not check
    
    Fixes FS#988
    
    Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
---
 package/base-files/Makefile               |  2 +-
 package/base-files/files/lib/functions.sh | 13 ++++++-------
 2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/package/base-files/Makefile b/package/base-files/Makefile
index e6c53e9..077bed4 100644
--- a/package/base-files/Makefile
+++ b/package/base-files/Makefile
@@ -11,7 +11,7 @@ include $(INCLUDE_DIR)/kernel.mk
 include $(INCLUDE_DIR)/version.mk
 
 PKG_NAME:=base-files
-PKG_RELEASE:=177
+PKG_RELEASE:=178
 PKG_FLAGS:=nonshared
 
 PKG_FILE_DEPENDS:=$(PLATFORM_DIR)/ $(GENERIC_PLATFORM_DIR)/base-files/
diff --git a/package/base-files/files/lib/functions.sh b/package/base-files/files/lib/functions.sh
index 4879a37..dfadfdb 100755
--- a/package/base-files/files/lib/functions.sh
+++ b/package/base-files/files/lib/functions.sh
@@ -202,7 +202,7 @@ add_group_and_user() {
 			if [ -n "$gname" ] && [ -n "$gid" ]; then
 				group_exists "$gname" || group_add "$gname" "$gid"
 			elif [ -n "$gname" ]; then
-				group_add_next "$gname"; gid=$?
+				gid="$(group_add_next "$gname")"
 			fi
 
 			if [ -n "$uname" ]; then
@@ -296,9 +296,7 @@ group_add() {
 	[ -f "${IPKG_INSTROOT}/etc/group" ] || return 1
 	[ -n "$IPKG_INSTROOT" ] || lock /var/lock/group
 	echo "${name}:x:${gid}:" >> ${IPKG_INSTROOT}/etc/group
-	rc=$?
 	[ -n "$IPKG_INSTROOT" ] || lock -u /var/lock/group
-	return $rc
 }
 
 group_exists() {
@@ -308,14 +306,17 @@ group_exists() {
 group_add_next() {
 	local gid gids
 	gid=$(grep -s "^${1}:" ${IPKG_INSTROOT}/etc/group | cut -d: -f3)
-	[ -n "$gid" ] && return $gid
+	if [ -n "$gid" ]; then
+		echo $gid
+		return
+	fi
 	gids=$(cat ${IPKG_INSTROOT}/etc/group | cut -d: -f3)
 	gid=65536
 	while [ -n "$(echo "$gids" | grep "^$gid$")" ] ; do
 	        gid=$((gid + 1))
 	done
 	group_add $1 $gid
-	return $gid
+	echo $gid
 }
 
 group_add_user() {
@@ -348,9 +349,7 @@ user_add() {
 	[ -n "$IPKG_INSTROOT" ] || lock /var/lock/passwd
 	echo "${name}:x:${uid}:${gid}:${desc}:${home}:${shell}" >> ${IPKG_INSTROOT}/etc/passwd
 	echo "${name}:x:0:0:99999:7:::" >> ${IPKG_INSTROOT}/etc/shadow
-	rc=$?
 	[ -n "$IPKG_INSTROOT" ] || lock -u /var/lock/passwd
-	return $rc
 }
 
 user_exists() {