busybox: fix the on-target upgrade problem

We now can have a 'one-binary' version of busybox, or 'two-binary'
version of busybox, controlled by the 'BUSYBOX_SPLIT_SUID' variable.
This makes on-target upgrade a problem, as we have to support the
following four upgrading paths.

For convenience, in the following context, A is used to denote a
'two-binary' version of busybox while B is used to denote a 'one-binary'
version of busybox.

A --(upgrade)--> B
B --(upgrade)--> A
A --(upgrade)--> A
B --(upgrade)--> B

This patch makes effort to support the above four situations.

[YOCTO #4802]

(From OE-Core rev: 4e571e97750f3ac6a62cd0d2d10c08be98230630)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 48 insertions, 0 deletions

diff --git a/meta/recipes-core/busybox/busybox.inc b/meta/recipes-core/busybox/busybox.inc
index 8567d6471f..acd2bfbcff 100644
--- a/meta/recipes-core/busybox/busybox.inc
+++ b/meta/recipes-core/busybox/busybox.inc
@@ -190,6 +190,10 @@ do_install () {
                         install -m 0644 ${S}/busybox.links.suid ${D}${sysconfdir}
                         install -m 0644 ${S}/busybox.links.nosuid ${D}${sysconfdir}
                         ln -sf busybox.nosuid ${D}${base_bindir}/sh
+                        # Keep a default busybox for people who want to invoke busybox directly.
+                        # This is also useful for the on device upgrade. Because we want
+                        # to use the busybox command in postinst.
+                        ln -sf busybox.nosuid ${D}${base_bindir}/busybox
                 else
                         if grep -q "CONFIG_FEATURE_SUID=y" ${B}/.config; then
                                 install -m 4755 ${B}/busybox ${D}${base_bindir}
@@ -198,6 +202,12 @@ do_install () {
                         fi
                         install -m 0644 ${S}/busybox.links ${D}${sysconfdir}
                         ln -sf busybox ${D}${base_bindir}/sh
+                        # We make this symlink here to eliminate the error when upgrading together
+                        # with busybox-syslog. Without this symlink, the opkg may think of the
+                        # busybox.nosuid as obsolete and remove it, resulting in dead links like
+                        # /bin/sed -> /bin/busybox.nosuid. This will make upgrading busybox-syslog fail.
+                        # This symlink will be safely deleted in postinst, thus no negative effect.
+                        ln -sf busybox ${D}${base_bindir}/busybox.nosuid
                 fi
         else
                 install -d ${D}${base_bindir} ${D}${base_sbindir}
@@ -306,6 +316,44 @@ python do_package_prepend () {
         set_alternative_vars("/etc/busybox.links.suid", "/bin/busybox.suid")
 }
 
+pkg_postinst_${PN} () {
+        # This part of code is dedicated to the on target upgrade problem.
+        # It's known that if we don't make appropriate symlinks before update-alternatives calls,
+        # there will be errors indicating missing commands such as 'sed'.
+        # These symlinks will later be updated by update-alternatives calls.
+        test -n 2 > /dev/null || alias test='busybox test'
+        if test "x$D" = "x"; then
+                # Remove busybox.nosuid if it's a symlink, because this situation indicates
+                # that we're installing or upgrading to a one-binary busybox.
+                if test -h /bin/busybox.nosuid; then
+                        rm -f /bin/busybox.nosuid
+                fi
+                for suffix in "" ".nosuid" ".suid"; do
+                        if test -e /etc/busybox.links$suffix; then
+                                while read link; do
+                                        if test ! -e "$link"; then
+                                                case "$link" in
+                                                        /*/*/*)
+                                                                to="../../bin/busybox$suffix"
+                                                                ;;
+                                                        /bin/*)
+                                                                to="busybox$suffix"
+                                                                ;;
+                                                        /*/*)
+                                                                to="../bin/busybox$suffix"
+                                                                ;;
+                                                esac
+                                                # we can use busybox here because even if we are using splitted busybox
+                                                # we've made a symlink from /bin/busybox to /bin/busybox.nosuid.
+                                                busybox rm -f $link
+                                                busybox ln -s $to $link
+                                        fi
+                                done < /etc/busybox.links$suffix
+                        fi
+                done
+        fi
+}
+
 pkg_prerm_${PN} () {
         # This is so you can make busybox commit suicide - removing busybox with no other packages
         # providing its files, this will make update-alternatives work, but the update-rc.d part