fast-export: Allow pruned-references in mark file

fast-export can fail because of some pruned-reference when importing a
mark file.

The problem happens in the following scenario:

$ git fast-export --export-marks=MARKS master
(rewrite master)
$ git prune
$ git fast-export --import-marks=MARKS master

This might fail if some references have been removed by prune
because some marks will refer to no longer existing commits.
git-fast-export will not need these objects anyway as they were no
longer reachable.

We still need to update last_numid so we don't change the mapping
between marks and objects for remote-helpers.
Unfortunately, the mark file should not be rewritten without lost marks
if no new objects has been exported, as we could lose track of the last
last_numid.

Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
Reviewed-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-fast-export.txt b/Documentation/git-fast-export.txt
index d6487e1ce03a9c060ae41b7b7455c442c6ea58f3..feab7a3e4ecb56aa17c32bd555e907a51001ef1f 100644 (file)
--- a/Documentation/git-fast-export.txt
+++ b/Documentation/git-fast-export.txt
@@ -66,6 +66,8 @@ produced incorrect results if you gave these options.
        incremental runs.  As <file> is only opened and truncated
        at completion, the same path can also be safely given to
        \--import-marks.
+       The file will not be written if no new object has been
+       marked/exported.
 
 --import-marks=<file>::
        Before processing any input, load the marks specified in

diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index d380155d9cf8fedf133dddbae479a910decd55b2..f44b76cb330250f969a50fd684465dc5c1cb4ecc 100644 (file)
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -618,9 +618,12 @@ static void import_marks(char *input_file)
                        || *mark_end != ' ' || get_sha1(mark_end + 1, sha1))
                        die("corrupt mark line: %s", line);
 
+               if (last_idnum < mark)
+                       last_idnum = mark;
+
                object = parse_object(sha1);
                if (!object)
-                       die ("Could not read blob %s", sha1_to_hex(sha1));
+                       continue;
 
                if (object->flags & SHOWN)
                        error("Object %s already has a mark", sha1_to_hex(sha1));
@@ -630,8 +633,6 @@ static void import_marks(char *input_file)
                        continue;
 
                mark_object(object, mark);
-               if (last_idnum < mark)
-                       last_idnum = mark;
 
                object->flags |= SHOWN;
        }
@@ -645,6 +646,7 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
        struct string_list extra_refs = STRING_LIST_INIT_NODUP;
        struct commit *commit;
        char *export_filename = NULL, *import_filename = NULL;
+       uint32_t lastimportid;
        struct option options[] = {
                OPT_INTEGER(0, "progress", &progress,
                            N_("show progress after <n> objects")),
@@ -688,6 +690,7 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 
        if (import_filename)
                import_marks(import_filename);
+       lastimportid = last_idnum;
 
        if (import_filename && revs.prune_data.nr)
                full_tree = 1;
@@ -710,7 +713,7 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 
        handle_tags_and_duplicates(&extra_refs);
 
-       if (export_filename)
+       if (export_filename && lastimportid != last_idnum)
                export_marks(export_filename);
 
        if (use_done_feature)