fast-import: add support for new 'alias' command
fast-export and fast-import have nice --import-marks flags which allow for incremental migrations. However, if there is a mark in fast-export's file of marks without a corresponding mark in the one for fast-import, then we run the risk that fast-export tries to send new objects relative to the mark it knows which fast-import does not, causing fast-import to fail. This arises in practice when there is a filter of some sort running between the fast-export and fast-import processes which prunes some commits programmatically. Provide such a filter with the ability to alias pruned commits to their most recent non-pruned ancestor. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Elijah Newren committed
Oct 3, 2019 at 13:27 UTC
b8f50e5b60e2654fcbf5f72b682635ee2e624923
3 files changed
+79
-10
Documentation/git-fast-import.txt
+22
@@ -337,6 +337,13 @@ and control the current import process. More detailed discussion
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`commit` command. This command is optional and is not
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needed to perform an import.
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+`alias`::
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+ Record that a mark refers to a given object without first
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+ creating any new object. Using --import-marks and referring
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+ to missing marks will cause fast-import to fail, so aliases
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+ can provide a way to set otherwise pruned commits to a valid
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+ value (e.g. the nearest non-pruned ancestor).
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+
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`checkpoint`::
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Forces fast-import to close the current packfile, generate its
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unique SHA-1 checksum and index, and start a new packfile.
@@ -914,6 +921,21 @@ a data chunk which does not have an LF as its last byte.
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+
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The `LF` after `<delim> LF` is optional (it used to be required).
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+`alias`
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+~~~~~~~
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+Record that a mark refers to a given object without first creating any
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+new object.
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+
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+....
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+ 'alias' LF
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+ mark
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+ 'to' SP <commit-ish> LF
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+ LF?
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+....
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+
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+For a detailed description of `<commit-ish>` see above under `from`.
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+
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+
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`checkpoint`
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~~~~~~~~~~~~
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Forces fast-import to close the current packfile, start a new one, and to
fast-import.c
+52
-10
@@ -2491,18 +2491,14 @@ static void parse_from_existing(struct branch *b)
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}
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}
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-static int parse_from(struct branch *b)
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+static int parse_objectish(struct branch *b, const char *objectish)
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{
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- const char *from;
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struct branch *s;
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struct object_id oid;
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- if (!skip_prefix(command_buf.buf, "from ", &from))
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- return 0;
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-
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oidcpy(&oid, &b->branch_tree.versions[1].oid);
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- s = lookup_branch(from);
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+ s = lookup_branch(objectish);
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if (b == s)
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die("Can't create a branch from itself: %s", b->name);
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else if (s) {
@@ -2510,8 +2506,8 @@ static int parse_from(struct branch *b)
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oidcpy(&b->oid, &s->oid);
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oidcpy(&b->branch_tree.versions[0].oid, t);
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oidcpy(&b->branch_tree.versions[1].oid, t);
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- } else if (*from == ':') {
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- uintmax_t idnum = parse_mark_ref_eol(from);
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+ } else if (*objectish == ':') {
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+ uintmax_t idnum = parse_mark_ref_eol(objectish);
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struct object_entry *oe = find_mark(idnum);
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if (oe->type != OBJ_COMMIT)
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die("Mark :%" PRIuMAX " not a commit", idnum);
@@ -2525,13 +2521,13 @@ static int parse_from(struct branch *b)
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} else
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parse_from_existing(b);
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}
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- } else if (!get_oid(from, &b->oid)) {
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+ } else if (!get_oid(objectish, &b->oid)) {
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parse_from_existing(b);
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if (is_null_oid(&b->oid))
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b->delete = 1;
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}
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else
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- die("Invalid ref name or SHA1 expression: %s", from);
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+ die("Invalid ref name or SHA1 expression: %s", objectish);
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if (b->branch_tree.tree && !oideq(&oid, &b->branch_tree.versions[1].oid)) {
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release_tree_content_recursive(b->branch_tree.tree);
@@ -2542,6 +2538,26 @@ static int parse_from(struct branch *b)
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return 1;
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}
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+static int parse_from(struct branch *b)
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+{
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+ const char *from;
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+
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+ if (!skip_prefix(command_buf.buf, "from ", &from))
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+ return 0;
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+
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+ return parse_objectish(b, from);
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+}
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+
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+static int parse_objectish_with_prefix(struct branch *b, const char *prefix)
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+{
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+ const char *base;
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+
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+ if (!skip_prefix(command_buf.buf, prefix, &base))
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+ return 0;
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+
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+ return parse_objectish(b, base);
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+}
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+
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static struct hash_list *parse_merge(unsigned int *count)
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{
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struct hash_list *list = NULL, **tail = &list, *n;
@@ -3087,6 +3103,28 @@ static void parse_progress(void)
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skip_optional_lf();
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}
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+static void parse_alias(void)
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+{
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+ struct object_entry *e;
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+ struct branch b;
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+
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+ skip_optional_lf();
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+ read_next_command();
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+
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+ /* mark ... */
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+ parse_mark();
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+ if (!next_mark)
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+ die(_("Expected 'mark' command, got %s"), command_buf.buf);
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+
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+ /* to ... */
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+ memset(&b, 0, sizeof(b));
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+ if (!parse_objectish_with_prefix(&b, "to "))
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+ die(_("Expected 'to' command, got %s"), command_buf.buf);
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+ e = find_object(&b.oid);
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+ assert(e);
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+ insert_mark(next_mark, e);
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+}
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+
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static char* make_fast_import_path(const char *path)
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{
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if (!relative_marks_paths || is_absolute_path(path))
@@ -3214,6 +3252,8 @@ static int parse_one_feature(const char *feature, int from_stream)
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option_import_marks(arg, from_stream, 1);
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} else if (skip_prefix(feature, "export-marks=", &arg)) {
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option_export_marks(arg);
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+ } else if (!strcmp(feature, "alias")) {
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+ ; /* Don't die - this feature is supported */
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} else if (!strcmp(feature, "get-mark")) {
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; /* Don't die - this feature is supported */
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} else if (!strcmp(feature, "cat-blob")) {
@@ -3370,6 +3410,8 @@ int cmd_main(int argc, const char **argv)
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parse_checkpoint();
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else if (!strcmp("done", command_buf.buf))
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break;
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+ else if (!strcmp("alias", command_buf.buf))
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+ parse_alias();
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else if (starts_with(command_buf.buf, "progress "))
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parse_progress();
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else if (skip_prefix(command_buf.buf, "feature ", &v))
t/t9300-fast-import.sh
+5
@@ -111,6 +111,10 @@ test_expect_success 'A: create pack from stdin' '
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Tag of tag of our lovely commit
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EOF
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+ alias
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+ mark :8
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+ to :5
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+
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INPUT_END
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git fast-import --export-marks=marks.out <input &&
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git whatchanged master
@@ -195,6 +199,7 @@ test_expect_success 'A: verify marks output' '
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:5 $(git rev-parse --verify master^0)
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:6 $(git cat-file tag nested | grep object | cut -d" " -f 2)
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:7 $(git rev-parse --verify nested)
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+ :8 $(git rev-parse --verify master^0)
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EOF
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test_cmp expect marks.out
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'