[check-config] No warning in blank argument

If user run current script whthout argument, the script will search
config in default dir list, but output following message:
 | # script/check-config.sh
 | warning: /proc/config.gz seems not a kernel config, searching other paths for kernel config ...
            ^^^^^^^^^^^^^^^
 | info: reading kernel config from /boot/config-4.7.0_HEAD_523d939ef98fd712632d93a5a2b588e477a7565e_ ...
 | ...

We can make output better by restruct the code struct:
1: Specify nothing
   Show info, and search default dir
2: Specify a config file
   Use it directly
3: Specify a wrong config file
   Show warning, and search default dir
4: Specify a dir
   Info, and search specified dir

Test:
 | # script/check-config.sh
 | info: no config specified, searching for kernel config ...
 | info: reading kernel config from /boot/config-4.7.0_HEAD_523d939ef98fd712632d93a5a2b588e477a7565e_ ...
 |
 | # script/check-config.sh /linux/.config
 | info: reading kernel config from /linux/.config ...
 |
 | # script/check-config.sh /linux/.configgg
 | warning: /linux/.configgg seems not a kernel config, searching other paths for kernel config ...
 | info: reading kernel config from /boot/config-4.7.0_HEAD_523d939ef98fd712632d93a5a2b588e477a7565e_ ...
 |
 | # script/check-config.sh /linux
 | info: input is a directory, searching for kernel config in this directory...
 | info: reading kernel config from /linux/.config ...
 |

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>

script/check-config.sh

@@ -16,12 +16,6 @@ possibleConfigFiles=(
 	'.config'
 )
 	
-if [ $# -gt 0 ]; then
-	CONFIG="$1"
-else
-	: ${CONFIG:="${possibleConfigs[0]}"}
-fi
-
 if ! command -v zgrep &> /dev/null; then
 	zgrep() {
 		zcat "$2" | grep "$1"
@@ -115,29 +109,56 @@ check_distro_userns() {
 	fi
 }
 
-if [ ! -f "$CONFIG" ]; then
+is_config()
-	wrap_warning "warning: $CONFIG seems not a kernel config, searching other paths for kernel config ..."
+{
-	for tryConfig in "$CONFIG" "${possibleConfigs[@]}"; do
+	local config="$1"
+
+	# Todo: more check
+	[[ -f "$config" ]] && return 0
+	return 1
+}
+
+search_config()
+{
+	local target_dir="$1"
+	[[ "$target_dir" ]] || target_dir=("${possibleConfigs[@]}")
+
+	local tryConfig
+	for tryConfig in "${target_dir[@]}"; do
+		is_config "$tryConfig" && {
+			CONFIG="$tryConfig"
+			return
+		}
 		[[ -d "$tryConfig" ]] && {
 			for tryFile in "${possibleConfigFiles[@]}"; do
-				[[ -f "$tryConfig/$tryFile" ]] && {
+				is_config "$tryConfig/$tryFile" && {
-					tryConfig+="/$tryFile"
+					CONFIG="$tryConfig/$tryFile"
-					break
+					return
 				}
 			done
 		}
-		[[ -f "$tryConfig" ]] && {
-			CONFIG="$tryConfig"
-			break
-		}
 	done
-	if [ ! -f "$CONFIG" ]; then
+
-		wrap_warning "error: cannot find kernel config"
+	wrap_warning "error: cannot find kernel config"
-		wrap_warning "  try running this script again, specifying the kernel config:"
+	wrap_warning "  try running this script again, specifying the kernel config:"
-		wrap_warning "    CONFIG=/path/to/kernel/.config $0 or $0 /path/to/kernel/.config"
+	wrap_warning "    CONFIG=/path/to/kernel/.config $0 or $0 /path/to/kernel/.config"
-		exit 1
+	exit 1
+}
+
+CONFIG="$1"
+
+is_config "$CONFIG" || {
+	if [[ ! "$CONFIG" ]]; then
+		wrap_color "info: no config specified, searching for kernel config ..." white
+		search_config
+	elif [[ -d "$CONFIG" ]]; then
+		wrap_color "info: input is a directory, searching for kernel config in this directory..." white
+		search_config "$CONFIG"
+	else
+		wrap_warning "warning: $CONFIG seems not a kernel config, searching other paths for kernel config ..."
+		search_config
 	fi
-fi
+}
 
 wrap_color "info: reading kernel config from $CONFIG ..." white
 echo