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<p>I considered a simpler approach without sfdisk, however
/proc/partitions may not update after writing the image directly
to the disk with dd, so an approach that actually read the
partition table from the device was used. Also, /proc/partitions
just lists block count, and not partition begin/end info.</p>
<p>As for the merit, this is quite useful on x86 systems. For
example, I'm booting using a 32gb usb drive and would prefer to
keep the other partitions I have defined intact after an upgrade.<br>
</p>
<div class="moz-cite-prefix">On 1/16/2016 9:24 PM, Luiz Angelo Daros
de Luca wrote:<br>
</div>
<blockquote
cite="mid:CAJq09z4dKf-9hKU0UQFiD=X5USJRb1dMFjwXyuZz6Shp7uBzrg@mail.gmail.com"
type="cite">
<p dir="ltr">Rob, I'll not judge the merit of keeping the previous
position table, but I guess dd might be enough for
saving/restore partitions (I guess only msdos is used). dd and
/proc/partitions might replace sfdisk.</p>
<br>
<div class="gmail_quote">
<div dir="ltr">Em sáb, 16 de jan de 2016 23:22, Rob Mosher <<a
moz-do-not-send="true"
href="mailto:nyt-openwrt@countercultured.net">nyt-openwrt@countercultured.net</a>>
escreveu:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">This patch
will save the partition table before an upgrade.<br>
If the installed image has not changed the partition structure<br>
the saved table will be restored, ensuring any user created<br>
partitions will be present after the upgrade.<br>
<br>
An option is added to sysupgrade to disable this feature.<br>
<br>
Signed-off-by: Rob Mosher <<a moz-do-not-send="true"
href="mailto:nyt-openwrt@countercultured.net"
target="_blank">nyt-openwrt@countercultured.net</a>><br>
---<br>
package/base-files/files/lib/upgrade/common.sh | 1 +<br>
package/base-files/files/sbin/sysupgrade | 3 ++<br>
target/linux/x86/Makefile | 2 +<br>
.../linux/x86/base-files/lib/upgrade/platform.sh | 45
++++++++++++++++++++++<br>
4 files changed, 51 insertions(+)<br>
<br>
diff --git a/package/base-files/files/lib/upgrade/common.sh
b/package/base-files/files/lib/upgrade/common.sh<br>
index 761b4c1..aed7f8e 100644<br>
--- a/package/base-files/files/lib/upgrade/common.sh<br>
+++ b/package/base-files/files/lib/upgrade/common.sh<br>
@@ -67,6 +67,7 @@ run_ramfs() { # <command> [...]<br>
install_bin /usr/sbin/ubirsvol<br>
install_bin /usr/sbin/ubirmvol<br>
install_bin /usr/sbin/ubimkvol<br>
+ install_bin /usr/sbin/sfdisk<br>
for file in $RAMFS_COPY_BIN; do<br>
install_bin ${file//:/ }<br>
done<br>
diff --git a/package/base-files/files/sbin/sysupgrade
b/package/base-files/files/sbin/sysupgrade<br>
index 93f0749..2f441f8 100755<br>
--- a/package/base-files/files/sbin/sysupgrade<br>
+++ b/package/base-files/files/sbin/sysupgrade<br>
@@ -10,6 +10,7 @@ export INTERACTIVE=0<br>
export VERBOSE=1<br>
export SAVE_CONFIG=1<br>
export SAVE_OVERLAY=0<br>
+export SAVE_PARTITIONS=1<br>
export DELAY=<br>
export CONF_IMAGE=<br>
export CONF_BACKUP_LIST=0<br>
@@ -29,6 +30,7 @@ while [ -n "$1" ]; do<br>
-q) export VERBOSE="$(($VERBOSE - 1))";;<br>
-n) export SAVE_CONFIG=0;;<br>
-c) export SAVE_OVERLAY=1;;<br>
+ -p) export SAVE_PARTITIONS=0;;<br>
-b|--create-backup) export CONF_BACKUP="$2"
NEED_IMAGE=1; shift;;<br>
-r|--restore-backup) export CONF_RESTORE="$2"
NEED_IMAGE=1; shift;;<br>
-l|--list-backup) export CONF_BACKUP_LIST=1;
break;;<br>
@@ -62,6 +64,7 @@ upgrade-option:<br>
-i interactive mode<br>
-c attempt to preserve all changed files in
/etc/<br>
-n do not save configuration over reflash<br>
+ -p do not attempt to restore the partition
table after flash.<br>
-T | --test<br>
Verify image and config .tar.gz but do
not actually flash.<br>
-F | --force<br>
diff --git a/target/linux/x86/Makefile
b/target/linux/x86/Makefile<br>
index e4bc0d9..e5b4378 100644<br>
--- a/target/linux/x86/Makefile<br>
+++ b/target/linux/x86/Makefile<br>
@@ -13,6 +13,8 @@ FEATURES:=squashfs ext4 vdi vmdk pcmcia
targz<br>
SUBTARGETS=generic xen_domu ep80579 geode kvm_guest 64<br>
MAINTAINER:=Felix Fietkau <<a moz-do-not-send="true"
href="mailto:nbd@openwrt.org" target="_blank">nbd@openwrt.org</a>><br>
<br>
+DEFAULT_PACKAGES += sfdisk<br>
+<br>
KERNEL_PATCHVER:=4.4<br>
<br>
KERNELNAME:=bzImage<br>
diff --git
a/target/linux/x86/base-files/lib/upgrade/platform.sh
b/target/linux/x86/base-files/lib/upgrade/platform.sh<br>
index 73ab5ef..7f5a2b1 100644<br>
--- a/target/linux/x86/base-files/lib/upgrade/platform.sh<br>
+++ b/target/linux/x86/base-files/lib/upgrade/platform.sh<br>
@@ -55,12 +55,57 @@ platform_copy_config() {<br>
fi<br>
}<br>
<br>
+save_bootparts() {<br>
+ disk=${BOOTPART%[0-9]}<br>
+ if [ -b $disk ]; then<br>
+ echo "Backing up partition table..."<br>
+ sfdisk -d $disk > /tmp/sfdisk.before<br>
+ grep size= /tmp/sfdisk.before | grep -E -v
'size=\s+0,' > /tmp/sfdisk.before.nonempty<br>
+ fi<br>
+}<br>
+<br>
+restore_bootparts() {<br>
+ disk=${BOOTPART%[0-9]}<br>
+ if [ -b $disk ]; then<br>
+ sfdisk -d $disk > /tmp/sfdisk.after<br>
+ grep size= /tmp/sfdisk.after | grep -E -v
'size=\s+0,' > /tmp/sfdisk.after.nonempty<br>
+ before=$(cat /tmp/sfdisk.before.nonempty)<br>
+ after=$(cat /tmp/sfdisk.after.nonempty)<br>
+<br>
+ #ensure we have both partition tables<br>
+ if [ -z "$before" -o -z "$after" ]; then<br>
+ echo "Could not read partition table"<br>
+ return 1<br>
+ fi<br>
+<br>
+ #if nothing changed, we do not need to restore<br>
+ if [ "$before" = "$after" ]; then<br>
+ echo "Parition layout unchanged"<br>
+ return 0<br>
+ fi<br>
+<br>
+ diff=$(grep -F -x -v -f
/tmp/sfdisk.before.nonempty /tmp/sfdisk.after.nonempty)<br>
+<br>
+ #if partition layout changed, do not restore<br>
+ if [ -n "$diff" ]; then<br>
+ echo "Partition layout changed, not
restoring."<br>
+ return 1<br>
+ fi<br>
+<br>
+ echo "Restoring partition table..."<br>
+ sfdisk $disk --force < /tmp/sfdisk.before
>&/dev/null<br>
+ fi<br>
+}<br>
+<br>
platform_do_upgrade() {<br>
platform_export_bootpart<br>
<br>
if [ -b "${BOOTPART%[0-9]}" ]; then<br>
sync<br>
+ [ $SAVE_PARTITIONS = "1" ] &&
save_bootparts<br>
get_image "$@" | dd of="${BOOTPART%[0-9]}"
bs=4096 conv=fsync<br>
sleep 1<br>
+ [ $SAVE_PARTITIONS = "1" ] &&
restore_bootparts<br>
fi<br>
}<br>
+<br>
--<br>
2.1.4<br>
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target="_blank">openwrt-devel@lists.openwrt.org</a><br>
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href="https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel"
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</blockquote>
</div>
<div dir="ltr">-- <br>
</div>
<p dir="ltr">Luiz Angelo Daros de Luca<br>
<a moz-do-not-send="true" href="mailto:luizluca@gmail.com">luizluca@gmail.com</a></p>
</blockquote>
<br>
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