[RFCv2 10/12] Introduce a 'marks <filename>' feature to the foreign transport code

The 'marks' feature is reported by the vcs helper when it requires the
fast-import marks database to loaded/saved by the git-fast-import process
that is executed by the foreign transport machinery. The feature is
advertised along with exactly one argument: the location of the file
containing the marks database.

Signed-off-by: Johan Herland <johan@xxxxxxxxxxx>
---
 Documentation/git-vcs.txt |    8 ++++++++
 transport-foreign.c       |   32 ++++++++++++++++++++++++++++++--
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-vcs.txt b/Documentation/git-vcs.txt
index 85656d4..75815ba 100644
--- a/Documentation/git-vcs.txt
+++ b/Documentation/git-vcs.txt
@@ -65,6 +65,14 @@ there may be other restrictions on what may be exported.
 FEATURES
 --------
 
+'marks' filename::
+       Helper requires the marks from a git-fast-import run to be loaded
+       from, and saved to, the given filename. When this "feature" is
+       advertised, each git-fast-import run must load and save the
+       internal marks database (see the --import-marks and --export-marks
+       option to git-fast-import for more details) located at the given
+       filename.
+
 'export'::
        Helper supports exporting commits, at least exporting
        non-merge commits whose parents are not the parents of any
diff --git a/transport-foreign.c b/transport-foreign.c
index be0a587..ae9cb9a 100644
--- a/transport-foreign.c
+++ b/transport-foreign.c
@@ -11,6 +11,7 @@ struct foreign_data
        struct child_process importer;
 
        /* capabilities */
+       char *marks_filename;
        unsigned export:1;
        unsigned export_branch:1;
        unsigned export_merges:1;
@@ -38,7 +39,12 @@ static void get_foreign_capabilities(struct foreign_data 
*fdata)
                        *eon = '\0';
 
                /* parse features */
-               if (!strcmp(buf.buf, "export"))
+               if (!strcmp(buf.buf, "marks")) {
+                       if (!eon)
+                               die("Feature 'marks' requires an argument");
+                       fdata->marks_filename = xstrdup(eon + 1);
+               }
+               else if (!strcmp(buf.buf, "export"))
                        fdata->export = 1;
                else if (!strcmp(buf.buf, "export-branch"))
                        fdata->export_branch = 1;
@@ -82,6 +88,7 @@ static int disconnect_foreign(struct transport *transport)
                write(fdata->importer.in, "\n", 1);
                close(fdata->importer.in);
                finish_command(&fdata->importer);
+               free(fdata->marks_filename);
                free(fdata);
                transport->data = NULL;
        }
@@ -91,10 +98,13 @@ static int disconnect_foreign(struct transport *transport)
 static int fetch_refs_via_foreign(struct transport *transport,
                                  int nr_heads, struct ref **to_fetch)
 {
+       struct foreign_data *fdata;
        struct child_process *importer;
        struct child_process fastimport;
        struct ref *posn;
+       struct strbuf export_marks, import_marks;
        int i, count;
+       FILE *f;
 
        count = 0;
        for (i = 0; i < nr_heads; i++) {
@@ -105,12 +115,28 @@ static int fetch_refs_via_foreign(struct transport 
*transport,
        }
        if (count) {
                importer = get_importer(transport);
+               fdata = (struct foreign_data *) transport->data;
+               strbuf_init(&export_marks, 0);
+               strbuf_init(&import_marks, 0);
 
                memset(&fastimport, 0, sizeof(fastimport));
                fastimport.in = importer->out;
-               fastimport.argv = xcalloc(3, sizeof(*fastimport.argv));
+               fastimport.argv = xcalloc(5, sizeof(*fastimport.argv));
                fastimport.argv[0] = "fast-import";
                fastimport.argv[1] = "--quiet";
+               if (fdata->marks_filename) {
+                       strbuf_addf(&export_marks, "--export-marks=%s",
+                               fdata->marks_filename);
+                       fastimport.argv[2] = export_marks.buf;
+
+                       f = fopen(fdata->marks_filename, "r");
+                       if (f) {
+                               strbuf_addf(&import_marks, "--import-marks=%s",
+                                       fdata->marks_filename);
+                               fastimport.argv[3] = import_marks.buf;
+                               fclose(f);
+                       }
+               }
                fastimport.git_cmd = 1;
                start_command(&fastimport);
 
@@ -124,6 +150,8 @@ static int fetch_refs_via_foreign(struct transport 
*transport,
                }
                disconnect_foreign(transport);
                finish_command(&fastimport);
+               strbuf_release(&export_marks);
+               strbuf_release(&import_marks);
        }
        for (i = 0; i < nr_heads; i++) {
                posn = to_fetch[i];
-- 
1.6.4.rc3.138.ga6b98.dirty

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