Implement a remote helper for svn in C
authorFlorian Achleitner <florian.achleitner.2.6.31@gmail.com>
Wed, 19 Sep 2012 15:21:15 +0000 (17:21 +0200)
committerJunio C Hamano <gitster@pobox.com>
Sun, 7 Oct 2012 21:10:16 +0000 (14:10 -0700)
Enable basic fetching from subversion repositories. When processing
remote URLs starting with testsvn::, git invokes this remote-helper.
It starts svnrdump to extract revisions from the subversion repository
in the 'dump file format', and converts them to a git-fast-import stream
using the functions of vcs-svn/.

Imported refs are created in a private namespace at
refs/svn/<remote-name>/master. The revision history is imported
linearly (no branch detection) and completely, i.e. from revision 0 to
HEAD.

The 'bidi-import' capability is used. The remote-helper expects data
from fast-import on its stdin. It buffers a batch of 'import' command
lines in a string_list before starting to process them.

Signed-off-by: Florian Achleitner <florian.achleitner.2.6.31@gmail.com>
Acked-by: David Michael Barr <b@rr-dav.id.au>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
remote-testsvn.c [new file with mode: 0644]
diff --git a/remote-testsvn.c b/remote-testsvn.c
new file mode 100644 (file)
index 0000000..c30ffcd
--- /dev/null
@@ -0,0 +1,176 @@
+#include "cache.h"
+#include "remote.h"
+#include "strbuf.h"
+#include "url.h"
+#include "exec_cmd.h"
+#include "run-command.h"
+#include "vcs-svn/svndump.h"
+#include "notes.h"
+#include "argv-array.h"
+
+static const char *url;
+static const char *private_ref;
+static const char *remote_ref = "refs/heads/master";
+
+static int cmd_capabilities(const char *line);
+static int cmd_import(const char *line);
+static int cmd_list(const char *line);
+
+typedef int (*input_command_handler)(const char *);
+struct input_command_entry {
+       const char *name;
+       input_command_handler fn;
+       unsigned char batchable;        /* whether the command starts or is part of a batch */
+};
+
+static const struct input_command_entry input_command_list[] = {
+       { "capabilities", cmd_capabilities, 0 },
+       { "import", cmd_import, 1 },
+       { "list", cmd_list, 0 },
+       { NULL, NULL }
+};
+
+static int cmd_capabilities(const char *line)
+{
+       printf("import\n");
+       printf("bidi-import\n");
+       printf("refspec %s:%s\n\n", remote_ref, private_ref);
+       fflush(stdout);
+       return 0;
+}
+
+static void terminate_batch(void)
+{
+       /* terminate a current batch's fast-import stream */
+       printf("done\n");
+       fflush(stdout);
+}
+
+static int cmd_import(const char *line)
+{
+       int code;
+       int dumpin_fd;
+       unsigned int startrev = 0;
+       struct argv_array svndump_argv = ARGV_ARRAY_INIT;
+       struct child_process svndump_proc;
+
+       memset(&svndump_proc, 0, sizeof(struct child_process));
+       svndump_proc.out = -1;
+       argv_array_push(&svndump_argv, "svnrdump");
+       argv_array_push(&svndump_argv, "dump");
+       argv_array_push(&svndump_argv, url);
+       argv_array_pushf(&svndump_argv, "-r%u:HEAD", startrev);
+       svndump_proc.argv = svndump_argv.argv;
+
+       code = start_command(&svndump_proc);
+       if (code)
+               die("Unable to start %s, code %d", svndump_proc.argv[0], code);
+       dumpin_fd = svndump_proc.out;
+
+       svndump_init_fd(dumpin_fd, STDIN_FILENO);
+       svndump_read(url, private_ref);
+       svndump_deinit();
+       svndump_reset();
+
+       close(dumpin_fd);
+       code = finish_command(&svndump_proc);
+       if (code)
+               warning("%s, returned %d", svndump_proc.argv[0], code);
+       argv_array_clear(&svndump_argv);
+
+       return 0;
+}
+
+static int cmd_list(const char *line)
+{
+       printf("? %s\n\n", remote_ref);
+       fflush(stdout);
+       return 0;
+}
+
+static int do_command(struct strbuf *line)
+{
+       const struct input_command_entry *p = input_command_list;
+       static struct string_list batchlines = STRING_LIST_INIT_DUP;
+       static const struct input_command_entry *batch_cmd;
+       /*
+        * commands can be grouped together in a batch.
+        * Batches are ended by \n. If no batch is active the program ends.
+        * During a batch all lines are buffered and passed to the handler function
+        * when the batch is terminated.
+        */
+       if (line->len == 0) {
+               if (batch_cmd) {
+                       struct string_list_item *item;
+                       for_each_string_list_item(item, &batchlines)
+                               batch_cmd->fn(item->string);
+                       terminate_batch();
+                       batch_cmd = NULL;
+                       string_list_clear(&batchlines, 0);
+                       return 0;       /* end of the batch, continue reading other commands. */
+               }
+               return 1;       /* end of command stream, quit */
+       }
+       if (batch_cmd) {
+               if (prefixcmp(batch_cmd->name, line->buf))
+                       die("Active %s batch interrupted by %s", batch_cmd->name, line->buf);
+               /* buffer batch lines */
+               string_list_append(&batchlines, line->buf);
+               return 0;
+       }
+
+       for (p = input_command_list; p->name; p++) {
+               if (!prefixcmp(line->buf, p->name) && (strlen(p->name) == line->len ||
+                               line->buf[strlen(p->name)] == ' ')) {
+                       if (p->batchable) {
+                               batch_cmd = p;
+                               string_list_append(&batchlines, line->buf);
+                               return 0;
+                       }
+                       return p->fn(line->buf);
+               }
+       }
+       die("Unknown command '%s'\n", line->buf);
+       return 0;
+}
+
+int main(int argc, const char **argv)
+{
+       struct strbuf buf = STRBUF_INIT, url_sb = STRBUF_INIT,
+                       private_ref_sb = STRBUF_INIT;
+       static struct remote *remote;
+       const char *url_in;
+
+       git_extract_argv0_path(argv[0]);
+       setup_git_directory();
+       if (argc < 2 || argc > 3) {
+               usage("git-remote-svn <remote-name> [<url>]");
+               return 1;
+       }
+
+       remote = remote_get(argv[1]);
+       url_in = (argc == 3) ? argv[2] : remote->url[0];
+
+       end_url_with_slash(&url_sb, url_in);
+       url = url_sb.buf;
+
+       strbuf_addf(&private_ref_sb, "refs/svn/%s/master", remote->name);
+       private_ref = private_ref_sb.buf;
+
+       while (1) {
+               if (strbuf_getline(&buf, stdin, '\n') == EOF) {
+                       if (ferror(stdin))
+                               die("Error reading command stream");
+                       else
+                               die("Unexpected end of command stream");
+               }
+               if (do_command(&buf))
+                       break;
+               strbuf_reset(&buf);
+       }
+
+       strbuf_release(&buf);
+       strbuf_release(&url_sb);
+       strbuf_release(&private_ref_sb);
+       return 0;
+}