[PATCH 4/5] Draft of API for git-vcs-*, transport.c code to use it.
---
Documentation/git-vcs.txt | 93 ++++++++++++++++++++++++++++++++++++++
transport.c | 109 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 202 insertions(+), 0 deletions(-)
create mode 100644 Documentation/git-vcs.txt
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
Daniel Barkalow <barkalow@iabervon.org>