basic rollback on the first stage of migration

tag relocation is unlikely to fail

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

tools/git-vault-gc.sh

@@ -79,10 +79,39 @@ fi
 
 cmd=$(gen_cmd)
 
+function git_gc {
+    echo "GC"
+    git prune
+    git gc --aggressive
+    echo "PRUNE+"
+    git prune
+}
+
+function rollback {
+    echo "ROLLBACK"
+    git reset --hard
+    git clean -fd
+    git checkout master
+    git branch -D migrate
+    for t in $(git tag | grep '^migrate/'); do
+        git tag -d "$t"
+    done
+    git_gc
+    error "during migration"
+}
+
+export -f rollback
+
 eval "$cmd" || error "$cmd"
+
+echo "REPLACE MASTER"
+# do it separetely to be on the safe side
+(git branch -D master && git branch -m migrate master) || error "replacing master"
+
+echo "CLEAR REFLOG"
 git reflog expire --expire=now --all || error "exiring reflog"
 
-echo "Removing dangling blobs"
+echo "REMOVING DANGLING BLOBS"
 for obj in $(git fsck --unreachable master \
     | grep '^unreachable blob' \
     | sed 's/unreachable blob //'); do
@@ -95,9 +124,5 @@ for obj in $(git fsck --unreachable master \
             || echo "No such blob $blob"
     done
 done
-echo "git prune+gc"
-git prune
-git gc --aggressive
-echo "git prune"
-git prune
+git_gc
 echo "OK"

tools/git-vault-rebase-generate.awk

@@ -98,16 +98,15 @@ $1 == "start" {
 }
 
 END {
-    for (i = 1; i <= length(move_tags); i++) {
-        push_command(move_tags[i]);
-    }
-    push_command("git branch -D master");
-    push_command("git branch -m migrate master");
-    res = ""
+    res = "(("
     sep = ""
     for (i = 1; i <= length(commands); i++) {
         res = res sep commands[i];
         sep = " && \\\n\t"
     }
+    res = res ") || rollback)"
+    for (i = 1; i <= length(move_tags); i++) {
+        res = res sep move_tags[i];
+    }
     print res;
 }