Daniel Barkalow--- Documentation/git-vcs.txt | 93 ++++++++++++++++++++++++++++++++++++++ transport.c | 109 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 202 insertions(+), 0 deletions(-) create mode 100644 Documentation/git-vcs.txt
Show changes to 2 files +202 −0
Documentation/git-vcs.txt, transport.c
diff --git a/Documentation/git-vcs.txt b/Documentation/git-vcs.txt new file mode 100644 index 0000000..fa02b76 --- /dev/null +++ b/Documentation/git-vcs.txt @@ -0,0 +1,93 @@ +git-vcs-*(1) +============ + +NAME +---- +git-vcs-* - Helper programs for interoperation with foreign systems + +SYNOPSIS +-------- +'git vcs-<system>' <command> [options] [arguments] + +DESCRIPTION +----------- + +These programs are normally not used directly by end users, but are +invoked by various git programs that interact with remote repositories +when the repository they would operate on is part of a foreign +system. + +Each 'git vcs-<system>' is a helper for interoperating with a +particular version control system. Different helpers have different +capabilities (limited both be the particular helper and by the +capabilities of the system they connect to), and they report what +capabilities they support. + +In general, these programs interact with a portion of the refs +namespace that isn't used by the rest of git. The configuration will +then (generally) map these refs into the remotes namespace. This +allows the importer to do whatever it wants with its refs without +affecting the state visible to normal git programs. + +COMMANDS +-------- + +'capabilities':: + Prints the capabilities of the helper, one per line. These are: + - import: the basic import command + - marks: import should be done with a saved marks file + - find-new-branches: detect new branches + - export: the general export command + - fork: create a new branch and export to it + - anonymous-fork: make commits on a branch without an inherent name + - merge: merge branches (of whatever type the system supports) + + If the helper doesn't support "merge", the default for pull is + to rebase instead of merging. + +'list':: + Takes the remote name, and outputs the names of refs. These + may be followed, after a single space, by "changed" or + "unchanged", indicating whether the foreign repository has + changed from the state in the ref. If the helper doesn't know, + it doesn't have to provide a value. (In particular, it + shouldn't do expensive operations, such as importing the + content, to see whether it matches.) + +'import':: + Takes the remote name and a list of names of refs, and imports + whatever it describes, by outputting it in git-fast-import + format. + +'export':: + Sends the branch to the foreign system and reimports it in + fast-import format. + + Reads a list of commits from stdin, where each commit has no + parents which were neither produced by an earlier import nor + appearing earlier in the list, where some commit has the old + value of the branch as a parent, and where all commits listed + are ancestors of the last one. Furthermore: + + - if the system doesn't support merges, each of these commits + has only a single parent; + + - if the system doesn't support anonymous branches, the first + commit has the old value of the branch as a parent (if the + branch already had a value), and all parents are either the + commit listed immediately before or produced by an earlier + import; + + - if the system doesn't support many-way merges, each commit + has at most two parents. + + export produces output in fast-import format giving the + content after a round-trip through the foreign system. This + also contains extra headers to report the mapping of original + git commits to reimported git commits (to facilitate rewriting + local branches to use the history-as-reimported instead of the + git-only version). + + export reports how much it managed to export by producing + commits in the fast-import stream that replace the listed + items that were successfully exported. diff --git a/transport.c b/transport.c index 8a37db5..fe78169 100644 --- a/transport.c +++ b/transport.c @@ -916,6 +916,113 @@ static int disconnect_git(struct transport *transport) return 0; } +static int fetch_refs_via_foreign(struct transport *transport, + int nr_heads, struct ref **to_fetch) +{ + struct remote *remote = transport->remote; + struct child_process importer; + struct child_process fastimport; + struct ref *posn; + int i, count; + struct strbuf buf; + + memset(&importer, 0, sizeof(importer)); + importer.in = 0; + importer.no_stdin = 1; + importer.out = -1; + importer.err = 0; + importer.argv = xcalloc(5 + nr_heads, sizeof(*importer.argv)); + strbuf_init(&buf, 80); + strbuf_addf(&buf, "vcs-%s", remote->foreign_vcs); + importer.argv[0] = buf.buf; + importer.argv[1] = "import"; + importer.argv[2] = remote->name; + count = 0; + for (i = 0; i < nr_heads; i++) { + posn = to_fetch[i]; + if (posn->status & REF_STATUS_UPTODATE) + continue; + importer.argv[3 + count] = posn->name; + count++; + } + importer.git_cmd = 1; + if (count) { + start_command(&importer); + + memset(&fastimport, 0, sizeof(fastimport)); + fastimport.in = importer.out; + fastimport.argv = xcalloc(3, sizeof(*fastimport.argv)); + fastimport.argv[0] = "fast-import"; + fastimport.argv[1] = "--quiet"; + fastimport.git_cmd = 1; + start_command(&fastimport); + + finish_command(&importer); + finish_command(&fastimport); + } + strbuf_release(&buf); + for (i = 0; i < nr_heads; i++) { + posn = to_fetch[i]; + if (posn->status & REF_STATUS_UPTODATE) + continue; + read_ref(posn->name, posn->old_sha1); + count++; + } + return 0; +} + +static struct ref *get_refs_via_foreign(struct transport *transport) +{ + struct remote *remote = transport->remote; + struct child_process importer; + struct ref *ret = NULL; + struct ref **end = &ret; + struct strbuf buf; + memset(&importer, 0, sizeof(importer)); + importer.in = 0; + importer.no_stdin = 1; + importer.out = -1; + importer.err = 0; + importer.argv = xcalloc(5, sizeof(*importer.argv)); + strbuf_init(&buf, 80); + strbuf_addf(&buf, "vcs-%s", remote->foreign_vcs); + importer.argv[0] = buf.buf; + importer.argv[1] = "list"; + importer.argv[2] = remote->name; + importer.git_cmd = 1; + start_command(&importer); + + strbuf_reset(&buf); + while (1) { + char *eol, *eon; + if (strbuf_read(&buf, importer.out, 80) <= 0) + break; + while (1) { + eol = strchr(buf.buf, '\n'); + if (!eol) + break; + *eol = '\0'; + eon = strchr(buf.buf, ' '); + if (eon) + *eon = '\0'; + *end = alloc_ref(buf.buf); + if (eon) { + if (strstr(eon + 1, "unchanged")) { + (*end)->status |= REF_STATUS_UPTODATE; + if (read_ref((*end)->name, (*end)->old_sha1)) + die("Unchanged?"); + } + } + end = &((*end)->next); + strbuf_remove(&buf, 0, eol - buf.buf + 1); + } + } + + finish_command(&importer); + strbuf_release(&buf); + return ret; +} + static int is_local(const char *url) { const char *colon = strchr(url, ':'); @@ -940,6 +1047,8 @@ struct transport *transport_get(struct remote *remote, const char *url) ret->url = url; if (remote && remote->foreign_vcs) { + ret->get_refs_list = get_refs_via_foreign; + ret->fetch = fetch_refs_via_foreign; } else if (!prefixcmp(url, "rsync:")) { ret->get_refs_list = get_refs_via_rsync; ret->fetch = fetch_objs_via_rsync;
-- 1.6.2.1.476.g9bf04b
