Initial commit

poky/meta/recipes-core/volatile-binds/files/COPYING.MIT

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+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
+THE USE OR OTHER DEALINGS IN THE SOFTWARE.

poky/meta/recipes-core/volatile-binds/files/mount-copybind

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+#!/bin/sh
+#
+# Perform a bind mount, copying existing files as we do so to ensure the
+# overlaid path has the necessary content.
+# If the target is a directory and overlayfs is available (and the environment
+# variable MOUNT_COPYBIND_AVOID_OVERLAYFS=1 is not set), then an overlay mount
+# will be attempted first.
+
+if [ $# -lt 2 ]; then
+    echo >&2 "Usage: $0 spec mountpoint [OPTIONS]"
+    exit 1
+fi
+
+# e.g. /var/volatile/lib
+spec=$1
+
+# e.g. /var/lib
+mountpoint=$2
+
+if [ $# -gt 2 ]; then
+    options=$3
+else
+    options=
+fi
+
+[ -n "$options" ] && options=",$options"
+
+mkdir -p "${spec%/*}"
+
+if [ -d "$mountpoint" ]; then
+
+    if [ -d "$spec" ]; then
+        specdir_existed=yes
+    else
+        specdir_existed=no
+        mkdir "$spec"
+        # If the $spec directory is created we need to take care that
+        # the selinux context is correct
+        if command -v selinuxenabled > /dev/null 2>&1; then
+            if selinuxenabled; then
+                restorecon "$spec"
+            fi
+        fi
+    fi
+
+    # Fast version of calculating `dirname ${spec}`/.`basename ${spec}`-work
+    overlay_workdir="${spec%/*}/.${spec##*/}-work"
+    mkdir "${overlay_workdir}"
+
+    # Try to mount using overlay, which is must faster than copying files.
+    # If that fails, fall back to slower copy.
+    if command -v selinuxenabled > /dev/null 2>&1; then
+        if selinuxenabled; then
+            mountcontext=",rootcontext=$(matchpathcon -n "$mountpoint")"
+        fi
+    fi
+    if [ "$MOUNT_COPYBIND_AVOID_OVERLAYFS" = 1 ] || ! mount -t overlay overlay -olowerdir="$mountpoint",upperdir="$spec",workdir="$overlay_workdir""$mountcontext" "$mountpoint" > /dev/null 2>&1; then
+
+        if [ "$specdir_existed" != "yes" ]; then
+            cp -aPR "$mountpoint"/. "$spec/"
+        fi
+
+        mount -o "bind$options" "$spec" "$mountpoint"
+        # restore the selinux context.
+        if command -v selinuxenabled > /dev/null 2>&1; then
+            if selinuxenabled; then
+                restorecon -R "$mountpoint"
+            fi
+        fi
+    fi
+elif [ -f "$mountpoint" ]; then
+    if [ ! -f "$spec" ]; then
+        cp -aP "$mountpoint" "$spec"
+    fi
+
+    mount -o "bind$options" "$spec" "$mountpoint"
+    # restore the selinux context.
+    if command -v selinuxenabled > /dev/null 2>&1; then
+        if selinuxenabled; then
+            restorecon -R "$mountpoint"
+        fi
+    fi
+fi

poky/meta/recipes-core/volatile-binds/files/volatile-binds.service.in

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+[Unit]
+Description=Bind mount volatile @where@
+DefaultDependencies=no
+Before=local-fs.target
+RequiresMountsFor=@whatparent@ @whereparent@
+ConditionPathIsReadWrite=@whatparent@
+ConditionPathExists=@where@
+ConditionPathIsReadWrite=!@where@
+
+[Service]
+Type=oneshot
+RemainAfterExit=Yes
+Environment=MOUNT_COPYBIND_AVOID_OVERLAYFS=@avoid_overlayfs@
+ExecStart=/sbin/mount-copybind @what@ @where@
+ExecStop=/bin/umount @where@
+
+[Install]
+WantedBy=local-fs.target