Re: [PATCH v7 01/16] Implement a remote helper for svn in C

> 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>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  remote-testsvn.c |  174 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 174 insertions(+)
>  create mode 100644 remote-testsvn.c
>
> diff --git a/remote-testsvn.c b/remote-testsvn.c
> new file mode 100644
> index 0000000..ebe803b
> --- /dev/null
> +++ b/remote-testsvn.c
> @@ -0,0 +1,174 @@
> +#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;
> +	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(&buf, url_in);
> +	url = strbuf_detach(&buf, NULL);
> +
> +	strbuf_addf(&buf, "refs/svn/%s/master", remote->name);
> +	private_ref = strbuf_detach(&buf, NULL);
> +
> +	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);
> +	free((void*)url);
> +	free((void*)private_ref);