From 5eaf116d571a17fdc0bd14fdb6761557bc4fa763 Mon Sep 17 00:00:00 2001
From: "Robin H. Johnson" <robbat2@gentoo.org>
Date: Fri, 23 Jun 2017 14:51:16 -0700
Subject: linuxrc: show why switch_root might fail, and make related code more
 readable.

Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>
---
 defaults/initrd.scripts |  5 +++++
 defaults/linuxrc        | 19 ++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

(limited to 'defaults')

diff --git a/defaults/initrd.scripts b/defaults/initrd.scripts
index d00e1c7c..efc64211 100644
--- a/defaults/initrd.scripts
+++ b/defaults/initrd.scripts
@@ -567,6 +567,7 @@ findnfsmount() {
 			else
 				bad_msg "The DHCP Server did not send a valid root-path."
 				bad_msg "Please check your DHCP setup, or provide a nfsroot=<...> parameter."
+				return 1
 			fi
 		fi
 
@@ -590,6 +591,7 @@ findnfsmount() {
 					REAL_ROOT="/dev/nfs"
 				else
 					bad_msg "NFS Mounting failed. Is the path corrent ?"
+					return 1
 				fi
 			else
 				good_msg "Attempting to mount NFS root on ${NFSROOT} with options ${NFSOPTIONS}"
@@ -599,12 +601,15 @@ findnfsmount() {
 					REAL_ROOT="/dev/nfs"
 				else
 					bad_msg "NFS Mounting failed. Is the path correct ?"
+					return 1
 				fi
 				# FIXME: Need to start portmap and the other rpc daemons in
 				# order to remount rw.
 			fi
 
 		fi
+	else # IP / DHCP
+		return 1
 	fi
 }
 
diff --git a/defaults/linuxrc b/defaults/linuxrc
index 66f7bd98..b227ed2c 100644
--- a/defaults/linuxrc
+++ b/defaults/linuxrc
@@ -640,6 +640,7 @@ do
 		# Try to mount the device as ${NEW_ROOT}
 		if [ "${REAL_ROOT}" = '/dev/nfs' ]; then
 			findnfsmount
+			mountret=$?
 		else
 			# If $REAL_ROOT is a symlink
 			# Resolve it like util-linux mount does
@@ -648,15 +649,17 @@ do
 			if [ "${REAL_ROOTFLAGS}" = '' ]; then
 				good_msg "Using mount -t ${ROOTFSTYPE} -o ${MOUNT_STATE} ${REAL_ROOT} ${NEW_ROOT}"
 				mount -t ${ROOTFSTYPE} -o ${MOUNT_STATE} ${REAL_ROOT} ${NEW_ROOT}
+				mountret=$?
 			else
 				good_msg "Using mount -t ${ROOTFSTYPE} -o ${MOUNT_STATE},${REAL_ROOTFLAGS} ${REAL_ROOT} ${NEW_ROOT}"
 				mount -t ${ROOTFSTYPE} -o ${MOUNT_STATE},${REAL_ROOTFLAGS} ${REAL_ROOT} ${NEW_ROOT}
+				mountret=$?
 			fi
 		fi
 
 		# If mount is successful break out of the loop
 		# else not a good root and start over.
-		if [ "$?" = '0' ]
+		if [ "$mountret" = '0' ]
 		then
 			if [ -d ${NEW_ROOT}/dev -a -x "${NEW_ROOT}${REAL_INIT:-/sbin/init}" ] || [ "${REAL_ROOT}" = "/dev/nfs" ]
 			then
@@ -1037,12 +1040,22 @@ fi
 rundebugshell "before entering switch_root"
 
 # init_opts is set in the environment by the kernel when it parses the command line
-exec /sbin/switch_root -c "/dev/console" "${CHROOT}" "${REAL_INIT:-/sbin/init}" ${init_opts}
+init=${REAL_INIT:-/sbin/init}
+if ! mountpoint "${CHROOT}"; then
+	bad_msg "$CHROOT was not a mountpoint"
+elif [ ! -x ${CHROOT}/${init} ]; then
+	bad_msg "init=${init} does not exist in the rootfs!"
+elif [ $$ != 1 ]; then
+	bad_msg "PID was not 1! switch_root would fail"
+else
+	good_msg "Switching to real root: /sbin/switch_root -c /dev/console ${CHROOT} ${init} ${init_opts}"
+	exec /sbin/switch_root -c "/dev/console" "${CHROOT}" "${init}" ${init_opts}
+fi
 
 # If we get here, something bad has happened
 splash 'verbose'
 
-bad_msg "A fatal error has occured since ${REAL_INIT:-/sbin/init} did not"
+bad_msg "A fatal error has occured since ${init} did not"
 bad_msg "boot correctly. Trying to open a shell..."
 
 exec /bin/bash
-- 
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