Initial commit

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

@@ -0,0 +1,83 @@
+#!/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