[tools] export snapshot as file tree. Fixes MER#1384

git-vault-export shell script exports git tree corresponding to the snapshot and
resolves vault blobs symlinks to files. Vault C++ and QML API exportSnapshot()
to expose this functionality.

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>

include/vault/vault.hpp

@@ -102,6 +102,7 @@ class Vault
     std::tuple<QString, bool, QString> restoreUnit
     (const QString &, const QString &, const QString &);
 
+    std::tuple<int, QString, QString> exportSnapshot(QString const &, QString const&);
 private:
     bool setState(const QString &state);
     bool backupUnit(const QString &home, const QString &unit, const ProgressCallback &callback);

qml/Vault/vault.cpp

@@ -224,6 +224,19 @@ class Worker : public QObject
         }
     }
 
+    Q_INVOKABLE void exportSnapshot(const QString &snapshot, const QString &dstDir)
+    {
+        auto res = m_vault->exportSnapshot(snapshot, dstDir);
+        int rc = std::get<0>(res);
+        auto data = map({{"snapshot", snapshot}, {"dst", dstDir}
+                , {"rc", std::get<0>(res)}, {"stdout", std::get<1>(res)}
+                , {"stderr", std::get<2>(res)}});
+        if (!rc)
+            emit done(Vault::ExportSnapshot, data);
+        else
+            emit error(Vault::ExportSnapshot, data);
+    }
+
 signals:
     void progress(Vault::Operation op, const QVariantMap &map);
     void error(Vault::Operation op, const QVariantMap &error);
@@ -419,4 +432,11 @@ Q_INVOKABLE void Vault::restoreUnit(const QString &snapshot, const QString &unit
                               , Q_ARG(QString, unit));
 }
 
+void Vault::exportSnapshot(const QString &snapshot, const QString &dstDir)
+{
+    QMetaObject::invokeMethod(m_worker, "exportSnapshot"
+                              , Q_ARG(QString, snapshot)
+                              , Q_ARG(QString, dstDir));
+}
+
 #include "vault.moc"

qml/Vault/vault.hpp

@@ -29,7 +29,8 @@ class Vault : public QObject
         ExportImportPrepare,
         ExportImportExecute,
         Data,
-        Maintenance
+        Maintenance,
+        ExportSnapshot
     }
     Q_ENUMS(Operation);
 
@@ -67,6 +68,7 @@ class Vault : public QObject
     Q_INVOKABLE void tagSnapshot(const QString &message);
 
     Q_INVOKABLE void restoreUnit(const QString &, const QString &);
+    Q_INVOKABLE void exportSnapshot(const QString &, const QString &);
 
 signals:
     void rootChanged();

src/vault.cpp

@@ -797,6 +797,18 @@ bool Vault::restoreUnit(const QString &home, const QString &unit, const Progress
     return true;
 }
 
+std::tuple<int, QString, QString>
+Vault::exportSnapshot(const QString &snapshot, const QString &dstDir)
+{
+    debug::debug("Export snapshot", snapshot, "to", dstDir);
+    auto l = lock();
+    auto snapshotName = snapshot;
+    if (snapshotName[0] != '>')
+        snapshotName = QString(">") + snapshot;
+
+    return executeIn(root(), "git-vault-export", snapshotName, dstDir);
+}
+
 /**
  * \note thread-unsafe
  */

tools/CMakeLists.txt

@@ -1,7 +1,7 @@
 configure_file(vault-gc.service.in vault-gc.service @ONLY)
 
 install(
-  PROGRAMS git-vault-gc gc-default git-vault-snapshot-units
+  PROGRAMS git-vault-gc gc-default git-vault-snapshot-units git-vault-export
   DESTINATION ${TOOLS_DIR}
   )
 

tools/git-vault-export

@@ -0,0 +1,50 @@
+#!/bin/bash
+
+trace () {
+    echo "`basename $0`: ${@:1}" 1>&2;
+}
+
+error() {
+    trace $@
+    exit 1
+}
+
+[ $# -eq 2 ] || error "Usage: $0 snapshot dst_dir"
+
+SNAP=$1
+DST=$2
+
+if [ "${SNAP:0:1}" != ">" ]; then
+    SNAP=">$SNAP"
+fi
+
+git rev-parse --show-toplevel || error "Not a git dir $(pwd)"
+git rev-parse "$SNAP" >/dev/null || error "There is no snapshot $SNAP"
+[ -d $DST ] || error "There is no destination dir $DST"
+
+# only $DST itself is expected
+COUNT=$(find $DST -maxdepth 1 -not -name '.' | wc -l)
+if [ "x$COUNT" != "x1" ]; then
+    error "Dst dir $DST should be empty, found $COUNT entries"
+fi
+
+trace "Export $SNAP to the $DST"
+
+GIT_DIR=$(pwd)
+(git archive --format=tar "$SNAP" | tar -C $DST -xf -) || \
+    error "Export of $SNAP to the $DST is failed"
+
+find $DST -type l | grep '/blobs/' | while read -r LINK
+do
+    NAME=$(readlink $LINK)
+    # match minimal relative blob ref (path inside the tree is unit/blobs/link)
+    if [[ $NAME =~ \.\./\.\./\.git/blobs/ ]]; then
+        FNAME=$(basename $NAME)
+        DNAME="$GIT_DIR/.git/blobs/$(basename $(dirname $NAME))"
+        [ -d $DNAME ] || error "There is no blob dir $DNAME for $LINK"
+        FNAME="$DNAME/$FNAME"
+        [ -f $FNAME ] || error "There is no blob file $FNAME for $LINK"
+        unlink $LINK || error "Can't unlink $LINK"
+        cp $FNAME $LINK || error "Can't copy $FNAME to $LINK"
+    fi
+done