Improved error checking in kernel module.

* modules/kernel.eselect (do_set): Don't remove the old symlink
before we know that we have a valid new target. Simplify.
(set_symlink): Check if the new link target is valid, then remove
any old symlink, then set the new one.
(remove_symlink): Use rm -f.

2 files changed, 22 insertions, 16 deletions

diff --git a/ChangeLog b/ChangeLog
index 2b356bd..6deef3a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2017-05-06  Ulrich Müller  <ulm@gentoo.org>
 
+	* modules/kernel.eselect (do_set): Don't remove the old symlink
+	before we know that we have a valid new target. Simplify.
+	(set_symlink): Check if the new link target is valid, then remove
+	any old symlink, then set the new one.
+	(remove_symlink): Use rm -f.
+
 	* modules/kernel.eselect (set_symlink):
 	* modules/profile.eselect (set_symlink): Check range of number,
 	bug 617572. Thanks to Takuto Yoshida <otakuto.gentoo@gmail.com>.
diff --git a/modules/kernel.eselect b/modules/kernel.eselect
index e76c143..57b9b7e 100644
--- a/modules/kernel.eselect
+++ b/modules/kernel.eselect
@@ -35,7 +35,7 @@ find_targets() {
 
 # remove the kernel symlink
 remove_symlink() {
-	rm "${EROOT}/usr/src/linux"
+	rm -f "${EROOT}/usr/src/linux"
 }
 
 # set the kernel symlink
@@ -49,15 +49,19 @@ set_symlink() {
 		target=${targets[target-1]}
 	fi
 
-	if [[ -z ${target} ]]; then
-		die -q "Target \"$1\" doesn't appear to be valid!"
-	elif [[ -f ${EROOT}/usr/src/${target}/Makefile ]]; then
-		ln -s "${target}" "${EROOT}/usr/src/linux"
-	elif [[ -f ${EROOT}/usr/src/linux-${target}/Makefile ]]; then
-		ln -s "linux-${target}" "${EROOT}/usr/src/linux"
-	else
-		die -q "Target \"$1\" doesn't appear to be valid!"
+	if [[ -n ${target} ]]; then
+		if [[ -f ${EROOT}/usr/src/${target}/Makefile ]]; then
+			:
+		elif [[ -f ${EROOT}/usr/src/linux-${target}/Makefile ]]; then
+			target=linux-${target}
+		else					# target not valid
+			target=
+		fi
 	fi
+	[[ -n ${target} ]] || die -q "Target \"$1\" doesn't appear to be valid!"
+
+	remove_symlink || die -q "Couldn't remove existing symlink"
+	ln -s "${target}" "${EROOT}/usr/src/linux"
 }
 
 ### show action ###
@@ -114,14 +118,10 @@ do_set() {
 	[[ -z $1 ]] && die -q "You didn't tell me what to set the symlink to"
 	[[ $# -gt 1 ]] && die -q "Too many parameters"
 
-	if [[ -L ${EROOT}/usr/src/linux ]]; then
-		# existing symlink
-		remove_symlink || die -q "Couldn't remove existing symlink"
-		set_symlink "$1" || die -q "Couldn't set a new symlink"
-	elif [[ -e ${EROOT}/usr/src/linux ]]; then
+	if [[ -e ${EROOT}/usr/src/linux && ! -L ${EROOT}/usr/src/linux ]]; then
 		# we have something strange
 		die -q "${EROOT}/usr/src/linux exists but is not a symlink"
-	else
-		set_symlink "$1" || die -q "Couldn't set a new symlink"
 	fi
+
+	set_symlink "$1" || die -q "Couldn't set a new symlink"
 }