http*: add helper methods for fetching packs

The code handling the fetching of packs in http-push.c and
http-walker.c have been refactored into new methods and a new struct
(http_pack_request) in http.c. They are not meant to be invoked
elsewhere.

The new methods in http.c are
 - new_http_pack_request
 - finish_http_pack_request
 - release_http_pack_request

and the new struct is http_pack_request.

Add a function, new_http_pack_request(), that deals with the details of
coming up with the filename to store the retrieved packfile, resuming a
previously aborted request, and making a new curl request. Update
http-push.c::start_fetch_packed() and http-walker.c::fetch_pack() to
use this.

Add a function, finish_http_pack_request(), that deals with renaming
the pack, advancing the pack list, and installing the pack. Update
http-push.c::finish_request() and http-walker.c::fetch_pack to use
this.

Update release_request() in http-push.c and http-walker.c to invoke
release_http_pack_request() to clean up pack request helper data.

The local_stream member of the transfer_request struct in http-push.c
has been removed, as the packfile pointer will be managed in the struct
http_pack_request.

Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 106 insertions, 0 deletions

diff --git a/http.c b/http.c
index 0701a6f6e..381593441 100644
--- a/http.c
+++ b/http.c
@@ -1,4 +1,5 @@
 #include "http.h"
+#include "pack.h"
 
 int data_received;
 int active_requests;
@@ -889,3 +890,108 @@ cleanup:
 	free(url);
 	return ret;
 }
+
+void release_http_pack_request(struct http_pack_request *preq)
+{
+	if (preq->packfile != NULL) {
+		fclose(preq->packfile);
+		preq->packfile = NULL;
+		preq->slot->local = NULL;
+	}
+	if (preq->range_header != NULL) {
+		curl_slist_free_all(preq->range_header);
+		preq->range_header = NULL;
+	}
+	preq->slot = NULL;
+	free(preq->url);
+}
+
+int finish_http_pack_request(struct http_pack_request *preq)
+{
+	int ret;
+	struct packed_git **lst;
+
+	preq->target->pack_size = ftell(preq->packfile);
+
+	if (preq->packfile != NULL) {
+		fclose(preq->packfile);
+		preq->packfile = NULL;
+		preq->slot->local = NULL;
+	}
+
+	ret = move_temp_to_file(preq->tmpfile, preq->filename);
+	if (ret)
+		return ret;
+
+	lst = preq->lst;
+	while (*lst != preq->target)
+		lst = &((*lst)->next);
+	*lst = (*lst)->next;
+
+	if (verify_pack(preq->target))
+		return -1;
+	install_packed_git(preq->target);
+
+	return 0;
+}
+
+struct http_pack_request *new_http_pack_request(
+	struct packed_git *target, const char *base_url)
+{
+	char *url;
+	char *filename;
+	long prev_posn = 0;
+	char range[RANGE_HEADER_SIZE];
+	struct strbuf buf = STRBUF_INIT;
+	struct http_pack_request *preq;
+
+	preq = xmalloc(sizeof(*preq));
+	preq->target = target;
+	preq->range_header = NULL;
+
+	end_url_with_slash(&buf, base_url);
+	strbuf_addf(&buf, "objects/pack/pack-%s.pack",
+		sha1_to_hex(target->sha1));
+	url = strbuf_detach(&buf, NULL);
+	preq->url = xstrdup(url);
+
+	filename = sha1_pack_name(target->sha1);
+	snprintf(preq->filename, sizeof(preq->filename), "%s", filename);
+	snprintf(preq->tmpfile, sizeof(preq->tmpfile), "%s.temp", filename);
+	preq->packfile = fopen(preq->tmpfile, "a");
+	if (!preq->packfile) {
+		error("Unable to open local file %s for pack",
+		      preq->tmpfile);
+		goto abort;
+	}
+
+	preq->slot = get_active_slot();
+	preq->slot->local = preq->packfile;
+	curl_easy_setopt(preq->slot->curl, CURLOPT_FILE, preq->packfile);
+	curl_easy_setopt(preq->slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
+	curl_easy_setopt(preq->slot->curl, CURLOPT_URL, url);
+	curl_easy_setopt(preq->slot->curl, CURLOPT_HTTPHEADER,
+		no_pragma_header);
+
+	/*
+	 * If there is data present from a previous transfer attempt,
+	 * resume where it left off
+	 */
+	prev_posn = ftell(preq->packfile);
+	if (prev_posn>0) {
+		if (http_is_verbose)
+			fprintf(stderr,
+				"Resuming fetch of pack %s at byte %ld\n",
+				sha1_to_hex(target->sha1), prev_posn);
+		sprintf(range, "Range: bytes=%ld-", prev_posn);
+		preq->range_header = curl_slist_append(NULL, range);
+		curl_easy_setopt(preq->slot->curl, CURLOPT_HTTPHEADER,
+			preq->range_header);
+	}
+
+	return preq;
+
+abort:
+	free(filename);
+	return NULL;
+}