From 1bdca816412910e1206c15ef47f2a8a6b369b831 Mon Sep 17 00:00:00 2001 From: "brian m. carlson" Date: Sat, 22 Feb 2020 20:17:49 +0000 Subject: fast-import: add options for rewriting submodules When converting a repository using submodules from one hash algorithm to another, it is necessary to rewrite the submodules from the old algorithm to the new algorithm, since only references to submodules, not their contents, are written to the fast-export stream. Without rewriting the submodules, fast-import fails with an "Invalid dataref" error when encountering a submodule in another algorithm. Add a pair of options, --rewrite-submodules-from and --rewrite-submodules-to, that take a list of marks produced by fast-export and fast-import, respectively, when processing the submodule. Use these marks to map the submodule commits from the old algorithm to the new algorithm. We read marks into two corresponding struct mark_set objects and then perform a mapping from the old to the new using a hash table. This lets us reuse the same mark parsing code that is used elsewhere and allows us to efficiently read and match marks based on their ID, since mark files need not be sorted. Note that because we're using a khash table for the object IDs, and this table copies values of struct object_id instead of taking references to them, it's necessary to zero the struct object_id values that we use to insert and look up in the table. Otherwise, we would end up with SHA-1 values that don't match because of whatever stack garbage might be left in the unused area. Signed-off-by: brian m. carlson Signed-off-by: Junio C Hamano diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt index 7889f95..77c6b3d 100644 --- a/Documentation/git-fast-import.txt +++ b/Documentation/git-fast-import.txt @@ -122,6 +122,26 @@ Locations of Marks Files Relative and non-relative marks may be combined by interweaving --(no-)-relative-marks with the --(import|export)-marks= options. +Submodule Rewriting +~~~~~~~~~~~~~~~~~~~ + +--rewrite-submodules-from=::: +--rewrite-submodules-to=::: + Rewrite the object IDs for the submodule specified by from the values + used in the from to those used in the to . The from marks should + have been created by `git fast-export`, and the to marks should have been + created by `git fast-import` when importing that same submodule. ++ + may be any arbitrary string not containing a colon character, but the +same value must be used with both options when specifying corresponding marks. +Multiple submodules may be specified with different values for . It is an +error not to use these options in corresponding pairs. ++ +These options are primarily useful when converting a repository from one hash +algorithm to another; without them, fast-import will fail if it encounters a +submodule because it has no way of writing the object ID into the new hash +algorithm. + Performance and Compression Tuning ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ diff --git a/fast-import.c b/fast-import.c index 6711f71..202dda1 100644 --- a/fast-import.c +++ b/fast-import.c @@ -18,6 +18,7 @@ #include "object-store.h" #include "mem-pool.h" #include "commit-reach.h" +#include "khash.h" #define PACK_ID_BITS 16 #define MAX_PACK_ID ((1<hash, 0, sizeof(oid->hash)); + + algo = parse_oid_hex_any(hex, oid, end); + if (algo == GIT_HASH_UNKNOWN) + return -1; + + it = kh_get_oid_map(sub_oid_map, *oid); + /* No such object? */ + if (it == kh_end(sub_oid_map)) { + /* If we're using the same algorithm, pass it through. */ + if (hash_algos[algo].format_id == the_hash_algo->format_id) + return 0; + return -1; + } + oidcpy(oid, kh_value(sub_oid_map, it)); + return 0; +} + /* * Given a pointer into a string, parse a mark reference: * @@ -2232,7 +2272,7 @@ static void file_change_m(const char *p, struct branch *b) inline_data = 1; oe = NULL; /* not used with inline_data, but makes gcc happy */ } else { - if (parse_oid_hex(p, &oid, &p)) + if (parse_mapped_oid_hex(p, &oid, &p)) die("Invalid dataref: %s", command_buf.buf); oe = find_object(&oid); if (*p++ != ' ') @@ -2406,7 +2446,7 @@ static void note_change_n(const char *p, struct branch *b, unsigned char *old_fa inline_data = 1; oe = NULL; /* not used with inline_data, but makes gcc happy */ } else { - if (parse_oid_hex(p, &oid, &p)) + if (parse_mapped_oid_hex(p, &oid, &p)) die("Invalid dataref: %s", command_buf.buf); oe = find_object(&oid); if (*p++ != ' ') @@ -2941,7 +2981,7 @@ static void parse_cat_blob(const char *p) die("Unknown mark: %s", command_buf.buf); oidcpy(&oid, &oe->idx.oid); } else { - if (parse_oid_hex(p, &oid, &p)) + if (parse_mapped_oid_hex(p, &oid, &p)) die("Invalid dataref: %s", command_buf.buf); if (*p) die("Garbage after SHA1: %s", command_buf.buf); @@ -3005,6 +3045,42 @@ static struct object_entry *dereference(struct object_entry *oe, return find_object(oid); } +static void insert_mapped_mark(uintmax_t mark, void *object, void *cbp) +{ + struct object_id *fromoid = object; + struct object_id *tooid = find_mark(cbp, mark); + int ret; + khiter_t it; + + it = kh_put_oid_map(sub_oid_map, *fromoid, &ret); + /* We've already seen this object. */ + if (ret == 0) + return; + kh_value(sub_oid_map, it) = tooid; +} + +static void build_mark_map_one(struct mark_set *from, struct mark_set *to) +{ + for_each_mark(from, 0, insert_mapped_mark, to); +} + +static void build_mark_map(struct string_list *from, struct string_list *to) +{ + struct string_list_item *fromp, *top; + + sub_oid_map = kh_init_oid_map(); + + for_each_string_list_item(fromp, from) { + top = string_list_lookup(to, fromp->string); + if (!fromp->util) { + die(_("Missing from marks for submodule '%s'"), fromp->string); + } else if (!top || !top->util) { + die(_("Missing to marks for submodule '%s'"), fromp->string); + } + build_mark_map_one(fromp->util, top->util); + } +} + static struct object_entry *parse_treeish_dataref(const char **p) { struct object_id oid; @@ -3016,7 +3092,7 @@ static struct object_entry *parse_treeish_dataref(const char **p) die("Unknown mark: %s", command_buf.buf); oidcpy(&oid, &e->idx.oid); } else { /* */ - if (parse_oid_hex(*p, &oid, p)) + if (parse_mapped_oid_hex(*p, &oid, p)) die("Invalid dataref: %s", command_buf.buf); e = find_object(&oid); if (*(*p)++ != ' ') @@ -3222,6 +3298,26 @@ static void option_export_pack_edges(const char *edges) pack_edges = xfopen(edges, "a"); } +static void option_rewrite_submodules(const char *arg, struct string_list *list) +{ + struct mark_set *ms; + FILE *fp; + char *s = xstrdup(arg); + char *f = strchr(s, ':'); + if (!f) + die(_("Expected format name:filename for submodule rewrite option")); + *f = '\0'; + f++; + ms = xcalloc(1, sizeof(*ms)); + string_list_insert(list, s)->util = ms; + + fp = fopen(f, "r"); + if (!fp) + die_errno("cannot read '%s'", f); + read_mark_file(ms, fp, insert_oid_entry); + fclose(fp); +} + static int parse_one_option(const char *option) { if (skip_prefix(option, "max-pack-size=", &option)) { @@ -3284,6 +3380,11 @@ static int parse_one_feature(const char *feature, int from_stream) option_export_marks(arg); } else if (!strcmp(feature, "alias")) { ; /* Don't die - this feature is supported */ + } else if (skip_prefix(feature, "rewrite-submodules-to=", &arg)) { + option_rewrite_submodules(arg, &sub_marks_to); + } else if (skip_prefix(feature, "rewrite-submodules-from=", &arg)) { + option_rewrite_submodules(arg, &sub_marks_from); + } else if (skip_prefix(feature, "rewrite-submodules-from=", &arg)) { } else if (!strcmp(feature, "get-mark")) { ; /* Don't die - this feature is supported */ } else if (!strcmp(feature, "cat-blob")) { @@ -3389,6 +3490,7 @@ static void parse_argv(void) seen_data_command = 1; if (import_marks_file) read_marks(); + build_mark_map(&sub_marks_from, &sub_marks_to); } int cmd_main(int argc, const char **argv) diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh index ae9950a..22c6c27 100755 --- a/t/t9300-fast-import.sh +++ b/t/t9300-fast-import.sh @@ -3382,4 +3382,113 @@ test_expect_success 'X: handling encoding' ' git log -1 --format=%B encoding | grep $(printf "\317\200") ' +### +### series Y (submodules and hash algorithms) +### + +cat >Y-sub-input <<\Y_INPUT_END +blob +mark :1 +data 4 +foo + +reset refs/heads/master +commit refs/heads/master +mark :2 +author Full Name 1000000000 +0100 +committer Full Name 1000000000 +0100 +data 24 +Test submodule commit 1 +M 100644 :1 file + +blob +mark :3 +data 8 +foo +bar + +commit refs/heads/master +mark :4 +author Full Name 1000000001 +0100 +committer Full Name 1000000001 +0100 +data 24 +Test submodule commit 2 +from :2 +M 100644 :3 file +Y_INPUT_END + +# Note that the submodule object IDs are intentionally not translated. +cat >Y-main-input <<\Y_INPUT_END +blob +mark :1 +data 4 +foo + +reset refs/heads/master +commit refs/heads/master +mark :2 +author Full Name 2000000000 +0100 +committer Full Name 2000000000 +0100 +data 14 +Test commit 1 +M 100644 :1 file + +blob +mark :3 +data 73 +[submodule "sub1"] + path = sub1 + url = https://void.example.com/main.git + +commit refs/heads/master +mark :4 +author Full Name 2000000001 +0100 +committer Full Name 2000000001 +0100 +data 14 +Test commit 2 +from :2 +M 100644 :3 .gitmodules +M 160000 0712c5be7cf681388e355ef47525aaf23aee1a6d sub1 + +blob +mark :5 +data 8 +foo +bar + +commit refs/heads/master +mark :6 +author Full Name 2000000002 +0100 +committer Full Name 2000000002 +0100 +data 14 +Test commit 3 +from :4 +M 100644 :5 file +M 160000 ff729f5e62f72c0c3978207d9a80e5f3a65f14d7 sub1 +Y_INPUT_END + +cat >Y-marks <<\Y_INPUT_END +:2 0712c5be7cf681388e355ef47525aaf23aee1a6d +:4 ff729f5e62f72c0c3978207d9a80e5f3a65f14d7 +Y_INPUT_END + +test_expect_success 'Y: setup' ' + test_oid_cache <<-EOF + Ymaster sha1:9afed2f9161ddf416c0a1863b8b0725b00070504 + Ymaster sha256:c0a1010da1df187b2e287654793df01b464bd6f8e3f17fc1481a7dadf84caee3 + EOF +' + +test_expect_success 'Y: rewrite submodules' ' + git init main1 && + ( + cd main1 && + git init sub2 && + git -C sub2 fast-import --export-marks=../sub2-marks <../Y-sub-input && + git fast-import --rewrite-submodules-from=sub:../Y-marks \ + --rewrite-submodules-to=sub:sub2-marks <../Y-main-input && + test "$(git rev-parse master)" = "$(test_oid Ymaster)" + ) +' + test_done -- cgit v0.10.2-6-g49f6