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>

Author: rctay

http-push.c

@@ -1,6 +1,5 @@
 #include "cache.h"
 #include "commit.h"
-#include "pack.h"
 #include "tag.h"
 #include "blob.h"
 #include "http.h"
@@ -119,7 +118,6 @@ struct transfer_request
 	char filename[PATH_MAX];
 	char tmpfile[PATH_MAX];
 	int local_fileno;
-	FILE *local_stream;
 	enum transfer_state state;
 	CURLcode curl_result;
 	char errorstr[CURL_ERROR_SIZE];
@@ -452,16 +450,10 @@ static void start_mkcol(struct transfer_request *request)
 
 static void start_fetch_packed(struct transfer_request *request)
 {
-	char *url;
 	struct packed_git *target;
-	FILE *packfile;
-	char *filename;
-	long prev_posn = 0;
-	char range[RANGE_HEADER_SIZE];
-	struct curl_slist *range_header = NULL;
 
 	struct transfer_request *check_request = request_queue_head;
-	struct active_request_slot *slot;
+	struct http_pack_request *preq;
 
 	target = find_sha1_pack(request->obj->sha1, repo->packs);
 	if (!target) {
@@ -474,68 +466,35 @@ static void start_fetch_packed(struct transfer_request *request)
 	fprintf(stderr,	"Fetching pack %s\n", sha1_to_hex(target->sha1));
 	fprintf(stderr, " which contains %s\n", sha1_to_hex(request->obj->sha1));
 
-	filename = sha1_pack_name(target->sha1);
-	snprintf(request->filename, sizeof(request->filename), "%s", filename);
-	snprintf(request->tmpfile, sizeof(request->tmpfile),
-		 "%s.temp", filename);
-
-	url = xmalloc(strlen(repo->url) + 64);
-	sprintf(url, "%sobjects/pack/pack-%s.pack",
-		repo->url, sha1_to_hex(target->sha1));
+	preq = new_http_pack_request(target, repo->url);
+	if (preq == NULL) {
+		release_http_pack_request(preq);
+		repo->can_update_info_refs = 0;
+		return;
+	}
+	preq->lst = &repo->packs;
 
 	/* Make sure there isn't another open request for this pack */
 	while (check_request) {
 		if (check_request->state == RUN_FETCH_PACKED &&
-		    !strcmp(check_request->url, url)) {
-			free(url);
+		    !strcmp(check_request->url, preq->url)) {
+			release_http_pack_request(preq);
 			release_request(request);
 			return;
 		}
 		check_request = check_request->next;
 	}
 
-	packfile = fopen(request->tmpfile, "a");
-	if (!packfile) {
-		fprintf(stderr, "Unable to open local file %s for pack",
-			request->tmpfile);
-		repo->can_update_info_refs = 0;
-		free(url);
-		return;
-	}
-
-	slot = get_active_slot();
-	slot->callback_func = process_response;
-	slot->callback_data = request;
-	request->slot = slot;
-	request->local_stream = packfile;
-	request->userData = target;
-
-	request->url = url;
-	curl_easy_setopt(slot->curl, CURLOPT_FILE, packfile);
-	curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
-	curl_easy_setopt(slot->curl, CURLOPT_URL, url);
-	curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
-	slot->local = packfile;
-
-	/*
-	 * If there is data present from a previous transfer attempt,
-	 * resume where it left off
-	 */
-	prev_posn = ftell(packfile);
-	if (prev_posn>0) {
-		if (push_verbosely)
-			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);
-		range_header = curl_slist_append(range_header, range);
-		curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
-	}
+	preq->slot->callback_func = process_response;
+	preq->slot->callback_data = request;
+	request->slot = preq->slot;
+	request->userData = preq;
 
 	/* Try to get the request started, abort the request on error */
 	request->state = RUN_FETCH_PACKED;
-	if (!start_active_slot(slot)) {
+	if (!start_active_slot(preq->slot)) {
 		fprintf(stderr, "Unable to start GET request\n");
+		release_http_pack_request(preq);
 		repo->can_update_info_refs = 0;
 		release_request(request);
 	}
@@ -718,22 +677,17 @@ static void release_request(struct transfer_request *request)
 
 	if (request->local_fileno != -1)
 		close(request->local_fileno);
-	if (request->local_stream)
-		fclose(request->local_stream);
 	free(request->url);
 	free(request);
 }
 
 static void finish_request(struct transfer_request *request)
 {
 	struct stat st;
-	struct packed_git *target;
-	struct packed_git **lst;
-	struct active_request_slot *slot;
+	struct http_pack_request *preq;
 
 	request->curl_result = request->slot->curl_result;
 	request->http_code = request->slot->http_code;
-	slot = request->slot;
 	request->slot = NULL;
 
 	/* Keep locks active */
@@ -821,31 +775,21 @@ static void finish_request(struct transfer_request *request)
 			start_fetch_packed(request);
 
 	} else if (request->state == RUN_FETCH_PACKED) {
+		int fail = 1;
 		if (request->curl_result != CURLE_OK) {
 			fprintf(stderr, "Unable to get pack file %s\n%s",
 				request->url, curl_errorstr);
-			repo->can_update_info_refs = 0;
 		} else {
-			off_t pack_size = ftell(request->local_stream);
-
-			fclose(request->local_stream);
-			request->local_stream = NULL;
-			slot->local = NULL;
-			if (!move_temp_to_file(request->tmpfile,
-					       request->filename)) {
-				target = (struct packed_git *)request->userData;
-				target->pack_size = pack_size;
-				lst = &repo->packs;
-				while (*lst != target)
-					lst = &((*lst)->next);
-				*lst = (*lst)->next;
-
-				if (!verify_pack(target))
-					install_packed_git(target);
-				else
-					repo->can_update_info_refs = 0;
+			preq = (struct http_pack_request *)request->userData;
+
+			if (preq) {
+				if (finish_http_pack_request(preq) > 0)
+					fail = 0;
+				release_http_pack_request(preq);
 			}
 		}
+		if (fail)
+			repo->can_update_info_refs = 0;
 		release_request(request);
 	}
 }
@@ -900,7 +844,6 @@ static void add_fetch_request(struct object *obj)
 	request->lock = NULL;
 	request->headers = NULL;
 	request->local_fileno = -1;
-	request->local_stream = NULL;
 	request->state = NEED_FETCH;
 	request->next = request_queue_head;
 	request_queue_head = request;
@@ -940,7 +883,6 @@ static int add_send_request(struct object *obj, struct remote_lock *lock)
 	request->lock = lock;
 	request->headers = NULL;
 	request->local_fileno = -1;
-	request->local_stream = NULL;
 	request->state = NEED_PUSH;
 	request->next = request_queue_head;
 	request_queue_head = request;

http-walker.c

@@ -1,6 +1,5 @@
 #include "cache.h"
 #include "commit.h"
-#include "pack.h"
 #include "walker.h"
 #include "http.h"
 
@@ -590,19 +589,10 @@ static int fetch_indices(struct walker *walker, struct alt_base *repo)
 
 static int fetch_pack(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 {
-	char *url;
 	struct packed_git *target;
-	struct packed_git **lst;
-	FILE *packfile;
-	char *filename;
-	char tmpfile[PATH_MAX];
 	int ret;
-	long prev_posn = 0;
-	char range[RANGE_HEADER_SIZE];
-	struct curl_slist *range_header = NULL;
-
-	struct active_request_slot *slot;
 	struct slot_results results;
+	struct http_pack_request *preq;
 
 	if (fetch_indices(walker, repo))
 		return -1;
@@ -617,72 +607,33 @@ static int fetch_pack(struct walker *walker, struct alt_base *repo, unsigned cha
 			sha1_to_hex(sha1));
 	}
 
-	url = xmalloc(strlen(repo->base) + 65);
-	sprintf(url, "%s/objects/pack/pack-%s.pack",
-		repo->base, sha1_to_hex(target->sha1));
+	preq = new_http_pack_request(target, repo->base);
+	if (preq == NULL)
+		goto abort;
+	preq->lst = &repo->packs;
+	preq->slot->results = &results;
 
-	filename = sha1_pack_name(target->sha1);
-	snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
-	packfile = fopen(tmpfile, "a");
-	if (!packfile)
-		return error("Unable to open local file %s for pack",
-			     tmpfile);
-
-	slot = get_active_slot();
-	slot->results = &results;
-	curl_easy_setopt(slot->curl, CURLOPT_FILE, packfile);
-	curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
-	curl_easy_setopt(slot->curl, CURLOPT_URL, url);
-	curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
-	slot->local = packfile;
-
-	/*
-	 * If there is data present from a previous transfer attempt,
-	 * resume where it left off
-	 */
-	prev_posn = ftell(packfile);
-	if (prev_posn>0) {
-		if (walker->get_verbosely)
-			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);
-		range_header = curl_slist_append(range_header, range);
-		curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, range_header);
-	}
-
-	if (start_active_slot(slot)) {
-		run_active_slot(slot);
+	if (start_active_slot(preq->slot)) {
+		run_active_slot(preq->slot);
 		if (results.curl_result != CURLE_OK) {
-			fclose(packfile);
-			slot->local = NULL;
-			return error("Unable to get pack file %s\n%s", url,
-				     curl_errorstr);
+			error("Unable to get pack file %s\n%s", preq->url,
+			      curl_errorstr);
+			goto abort;
 		}
 	} else {
-		fclose(packfile);
-		slot->local = NULL;
-		return error("Unable to start request");
+		error("Unable to start request");
+		goto abort;
 	}
 
-	target->pack_size = ftell(packfile);
-	fclose(packfile);
-	slot->local = NULL;
-
-	ret = move_temp_to_file(tmpfile, filename);
+	ret = finish_http_pack_request(preq);
+	release_http_pack_request(preq);
 	if (ret)
 		return ret;
 
-	lst = &repo->packs;
-	while (*lst != target)
-		lst = &((*lst)->next);
-	*lst = (*lst)->next;
-
-	if (verify_pack(target))
-		return -1;
-	install_packed_git(target);
-
 	return 0;
+
+abort:
+	return -1;
 }
 
 static void abort_object_request(struct object_request *obj_req)