Introduce core.sharedrepository
[gitweb.git] / http-fetch.c
index 17051fe43ab15d5f4af6b9ae2d795b9b35800cb9..61b2188adbb68d94b2d5906be63c89bda879b4b0 100644 (file)
@@ -1,23 +1,16 @@
 #include "cache.h"
 #include "commit.h"
-
+#include "pack.h"
 #include "fetch.h"
+#include "http.h"
 
-#include <curl/curl.h>
-#include <curl/easy.h>
+#define PREV_BUF_SIZE 4096
+#define RANGE_HEADER_SIZE 30
 
-#if LIBCURL_VERSION_NUM < 0x070704
-#define curl_global_cleanup() do { /* nothing */ } while(0)
-#endif
-#if LIBCURL_VERSION_NUM < 0x070800
-#define curl_global_init(a) do { /* nothing */ } while(0)
-#endif
+static int got_alternates = -1;
 
-static CURL *curl;
 static struct curl_slist *no_pragma_header;
 
-static char *initial_base;
-
 struct alt_base
 {
        char *base;
@@ -26,33 +19,45 @@ struct alt_base
        struct alt_base *next;
 };
 
-struct alt_base *alt = NULL;
+static struct alt_base *alt = NULL;
 
-static SHA_CTX c;
-static z_stream stream;
-
-static int local;
-static int zret;
-
-static int curl_ssl_verify;
+enum object_request_state {
+       WAITING,
+       ABORTED,
+       ACTIVE,
+       COMPLETE,
+};
 
-struct buffer
+struct object_request
 {
-        size_t posn;
-        size_t size;
-        void *buffer;
+       unsigned char sha1[20];
+       struct alt_base *repo;
+       char *url;
+       char filename[PATH_MAX];
+       char tmpfile[PATH_MAX];
+       int local;
+       enum object_request_state state;
+       CURLcode curl_result;
+       char errorstr[CURL_ERROR_SIZE];
+       long http_code;
+       unsigned char real_sha1[20];
+       SHA_CTX c;
+       z_stream stream;
+       int zret;
+       int rename;
+       struct active_request_slot *slot;
+       struct object_request *next;
 };
 
-static size_t fwrite_buffer(void *ptr, size_t eltsize, size_t nmemb,
-                            struct buffer *buffer)
-{
-        size_t size = eltsize * nmemb;
-        if (size > buffer->size - buffer->posn)
-                size = buffer->size - buffer->posn;
-        memcpy(buffer->buffer + buffer->posn, ptr, size);
-        buffer->posn += size;
-        return size;
-}
+struct alternates_request {
+       char *base;
+       char *url;
+       struct buffer *buffer;
+       struct active_request_slot *slot;
+       int http_specific;
+};
+
+static struct object_request *object_queue_head = NULL;
 
 static size_t fwrite_sha1_file(void *ptr, size_t eltsize, size_t nmemb,
                               void *data)
@@ -60,66 +65,368 @@ static size_t fwrite_sha1_file(void *ptr, size_t eltsize, size_t nmemb,
        unsigned char expn[4096];
        size_t size = eltsize * nmemb;
        int posn = 0;
+       struct object_request *obj_req = (struct object_request *)data;
        do {
-               ssize_t retval = write(local, ptr + posn, size - posn);
+               ssize_t retval = write(obj_req->local,
+                                      ptr + posn, size - posn);
                if (retval < 0)
                        return posn;
                posn += retval;
        } while (posn < size);
 
-       stream.avail_in = size;
-       stream.next_in = ptr;
+       obj_req->stream.avail_in = size;
+       obj_req->stream.next_in = ptr;
        do {
-               stream.next_out = expn;
-               stream.avail_out = sizeof(expn);
-               zret = inflate(&stream, Z_SYNC_FLUSH);
-               SHA1_Update(&c, expn, sizeof(expn) - stream.avail_out);
-       } while (stream.avail_in && zret == Z_OK);
+               obj_req->stream.next_out = expn;
+               obj_req->stream.avail_out = sizeof(expn);
+               obj_req->zret = inflate(&obj_req->stream, Z_SYNC_FLUSH);
+               SHA1_Update(&obj_req->c, expn,
+                           sizeof(expn) - obj_req->stream.avail_out);
+       } while (obj_req->stream.avail_in && obj_req->zret == Z_OK);
+       data_received++;
        return size;
 }
 
-void prefetch(unsigned char *sha1)
+static void fetch_alternates(char *base);
+
+static void process_object_response(void *callback_data);
+
+static void start_object_request(struct object_request *obj_req)
 {
+       char *hex = sha1_to_hex(obj_req->sha1);
+       char prevfile[PATH_MAX];
+       char *url;
+       char *posn;
+       int prevlocal;
+       unsigned char prev_buf[PREV_BUF_SIZE];
+       ssize_t prev_read = 0;
+       long prev_posn = 0;
+       char range[RANGE_HEADER_SIZE];
+       struct curl_slist *range_header = NULL;
+       struct active_request_slot *slot;
+
+       snprintf(prevfile, sizeof(prevfile), "%s.prev", obj_req->filename);
+       unlink(prevfile);
+       rename(obj_req->tmpfile, prevfile);
+       unlink(obj_req->tmpfile);
+
+       if (obj_req->local != -1)
+               error("fd leakage in start: %d", obj_req->local);
+       obj_req->local = open(obj_req->tmpfile,
+                             O_WRONLY | O_CREAT | O_EXCL, 0666);
+       /* This could have failed due to the "lazy directory creation";
+        * try to mkdir the last path component.
+        */
+       if (obj_req->local < 0 && errno == ENOENT) {
+               char *dir = strrchr(obj_req->tmpfile, '/');
+               if (dir) {
+                       *dir = 0;
+                       mkdir(obj_req->tmpfile, 0777);
+                       *dir = '/';
+               }
+               obj_req->local = open(obj_req->tmpfile,
+                                     O_WRONLY | O_CREAT | O_EXCL, 0666);
+       }
+
+       if (obj_req->local < 0) {
+               obj_req->state = ABORTED;
+               error("Couldn't create temporary file %s for %s: %s\n",
+                     obj_req->tmpfile, obj_req->filename, strerror(errno));
+               return;
+       }
+
+       memset(&obj_req->stream, 0, sizeof(obj_req->stream));
+
+       inflateInit(&obj_req->stream);
+
+       SHA1_Init(&obj_req->c);
+
+       url = xmalloc(strlen(obj_req->repo->base) + 50);
+       obj_req->url = xmalloc(strlen(obj_req->repo->base) + 50);
+       strcpy(url, obj_req->repo->base);
+       posn = url + strlen(obj_req->repo->base);
+       strcpy(posn, "objects/");
+       posn += 8;
+       memcpy(posn, hex, 2);
+       posn += 2;
+       *(posn++) = '/';
+       strcpy(posn, hex + 2);
+       strcpy(obj_req->url, url);
+
+       /* If a previous temp file is present, process what was already
+          fetched. */
+       prevlocal = open(prevfile, O_RDONLY);
+       if (prevlocal != -1) {
+               do {
+                       prev_read = read(prevlocal, prev_buf, PREV_BUF_SIZE);
+                       if (prev_read>0) {
+                               if (fwrite_sha1_file(prev_buf,
+                                                    1,
+                                                    prev_read,
+                                                    obj_req) == prev_read) {
+                                       prev_posn += prev_read;
+                               } else {
+                                       prev_read = -1;
+                               }
+                       }
+               } while (prev_read > 0);
+               close(prevlocal);
+       }
+       unlink(prevfile);
+
+       /* Reset inflate/SHA1 if there was an error reading the previous temp
+          file; also rewind to the beginning of the local file. */
+       if (prev_read == -1) {
+               memset(&obj_req->stream, 0, sizeof(obj_req->stream));
+               inflateInit(&obj_req->stream);
+               SHA1_Init(&obj_req->c);
+               if (prev_posn>0) {
+                       prev_posn = 0;
+                       lseek(obj_req->local, SEEK_SET, 0);
+                       ftruncate(obj_req->local, 0);
+               }
+       }
+
+       slot = get_active_slot();
+       slot->callback_func = process_object_response;
+       slot->callback_data = obj_req;
+       obj_req->slot = slot;
+
+       curl_easy_setopt(slot->curl, CURLOPT_FILE, obj_req);
+       curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
+       curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, obj_req->errorstr);
+       curl_easy_setopt(slot->curl, CURLOPT_URL, url);
+       curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
+
+       /* If we have successfully processed data from a previous fetch
+          attempt, only fetch the data we don't already have. */
+       if (prev_posn>0) {
+               if (get_verbosely)
+                       fprintf(stderr,
+                               "Resuming fetch of object %s at byte %ld\n",
+                               hex, 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);
+       }
+
+       /* Try to get the request started, abort the request on error */
+       obj_req->state = ACTIVE;
+       if (!start_active_slot(slot)) {
+               obj_req->state = ABORTED;
+               obj_req->slot = NULL;
+               close(obj_req->local); obj_req->local = -1;
+               free(obj_req->url);
+               return;
+       }
+       
 }
 
-static int got_alternates = 0;
+static void finish_object_request(struct object_request *obj_req)
+{
+       struct stat st;
+
+       fchmod(obj_req->local, 0444);
+       close(obj_req->local); obj_req->local = -1;
+
+       if (obj_req->http_code == 416) {
+               fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
+       } else if (obj_req->curl_result != CURLE_OK) {
+               if (stat(obj_req->tmpfile, &st) == 0)
+                       if (st.st_size == 0)
+                               unlink(obj_req->tmpfile);
+               return;
+       }
+
+       inflateEnd(&obj_req->stream);
+       SHA1_Final(obj_req->real_sha1, &obj_req->c);
+       if (obj_req->zret != Z_STREAM_END) {
+               unlink(obj_req->tmpfile);
+               return;
+       }
+       if (memcmp(obj_req->sha1, obj_req->real_sha1, 20)) {
+               unlink(obj_req->tmpfile);
+               return;
+       }
+       obj_req->rename =
+               move_temp_to_file(obj_req->tmpfile, obj_req->filename);
+
+       if (obj_req->rename == 0)
+               pull_say("got %s\n", sha1_to_hex(obj_req->sha1));
+}
+
+static void process_object_response(void *callback_data)
+{
+       struct object_request *obj_req =
+               (struct object_request *)callback_data;
+
+       obj_req->curl_result = obj_req->slot->curl_result;
+       obj_req->http_code = obj_req->slot->http_code;
+       obj_req->slot = NULL;
+       obj_req->state = COMPLETE;
+
+       /* Use alternates if necessary */
+       if (obj_req->http_code == 404 ||
+           obj_req->curl_result == CURLE_FILE_COULDNT_READ_FILE) {
+               fetch_alternates(alt->base);
+               if (obj_req->repo->next != NULL) {
+                       obj_req->repo =
+                               obj_req->repo->next;
+                       close(obj_req->local);
+                       obj_req->local = -1;
+                       start_object_request(obj_req);
+                       return;
+               }
+       }
+
+       finish_object_request(obj_req);
+}
+
+static void release_object_request(struct object_request *obj_req)
+{
+       struct object_request *entry = object_queue_head;
+
+       if (obj_req->local != -1)
+               error("fd leakage in release: %d", obj_req->local);
+       if (obj_req == object_queue_head) {
+               object_queue_head = obj_req->next;
+       } else {
+               while (entry->next != NULL && entry->next != obj_req)
+                       entry = entry->next;
+               if (entry->next == obj_req)
+                       entry->next = entry->next->next;
+       }
+
+       free(obj_req->url);
+       free(obj_req);
+}
+
+#ifdef USE_CURL_MULTI
+void fill_active_slots(void)
+{
+       struct object_request *obj_req = object_queue_head;
+       struct active_request_slot *slot = active_queue_head;
+       int num_transfers;
+
+       while (active_requests < max_requests && obj_req != NULL) {
+               if (obj_req->state == WAITING) {
+                       if (has_sha1_file(obj_req->sha1))
+                               release_object_request(obj_req);
+                       else
+                               start_object_request(obj_req);
+                       curl_multi_perform(curlm, &num_transfers);
+               }
+               obj_req = obj_req->next;
+       }
+
+       while (slot != NULL) {
+               if (!slot->in_use && slot->curl != NULL) {
+                       curl_easy_cleanup(slot->curl);
+                       slot->curl = NULL;
+               }
+               slot = slot->next;
+       }                               
+}
+#endif
+
+void prefetch(unsigned char *sha1)
+{
+       struct object_request *newreq;
+       struct object_request *tail;
+       char *filename = sha1_file_name(sha1);
+
+       newreq = xmalloc(sizeof(*newreq));
+       memcpy(newreq->sha1, sha1, 20);
+       newreq->repo = alt;
+       newreq->url = NULL;
+       newreq->local = -1;
+       newreq->state = WAITING;
+       snprintf(newreq->filename, sizeof(newreq->filename), "%s", filename);
+       snprintf(newreq->tmpfile, sizeof(newreq->tmpfile),
+                "%s.temp", filename);
+       newreq->next = NULL;
+
+       if (object_queue_head == NULL) {
+               object_queue_head = newreq;
+       } else {
+               tail = object_queue_head;
+               while (tail->next != NULL) {
+                       tail = tail->next;
+               }
+               tail->next = newreq;
+       }
+
+#ifdef USE_CURL_MULTI
+       fill_active_slots();
+       step_active_slots();
+#endif
+}
 
 static int fetch_index(struct alt_base *repo, unsigned char *sha1)
 {
+       char *hex = sha1_to_hex(sha1);
        char *filename;
        char *url;
+       char tmpfile[PATH_MAX];
+       long prev_posn = 0;
+       char range[RANGE_HEADER_SIZE];
+       struct curl_slist *range_header = NULL;
 
        FILE *indexfile;
+       struct active_request_slot *slot;
 
        if (has_pack_index(sha1))
                return 0;
 
        if (get_verbosely)
-               fprintf(stderr, "Getting index for pack %s\n",
-                       sha1_to_hex(sha1));
+               fprintf(stderr, "Getting index for pack %s\n", hex);
        
        url = xmalloc(strlen(repo->base) + 64);
-       sprintf(url, "%s/objects/pack/pack-%s.idx",
-               repo->base, sha1_to_hex(sha1));
+       sprintf(url, "%s/objects/pack/pack-%s.idx", repo->base, hex);
        
        filename = sha1_pack_index_name(sha1);
-       indexfile = fopen(filename, "w");
+       snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
+       indexfile = fopen(tmpfile, "a");
        if (!indexfile)
                return error("Unable to open local file %s for pack index",
                             filename);
 
-       curl_easy_setopt(curl, CURLOPT_FILE, indexfile);
-       curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fwrite);
-       curl_easy_setopt(curl, CURLOPT_URL, url);
-       curl_easy_setopt(curl, CURLOPT_HTTPHEADER, no_pragma_header);
-       
-       if (curl_easy_perform(curl)) {
+       slot = get_active_slot();
+       curl_easy_setopt(slot->curl, CURLOPT_FILE, indexfile);
+       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 = indexfile;
+
+       /* If there is data present from a previous transfer attempt,
+          resume where it left off */
+       prev_posn = ftell(indexfile);
+       if (prev_posn>0) {
+               if (get_verbosely)
+                       fprintf(stderr,
+                               "Resuming fetch of index for pack %s at byte %ld\n",
+                               hex, 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 (slot->curl_result != CURLE_OK) {
+                       fclose(indexfile);
+                       return error("Unable to get pack index %s\n%s", url,
+                                    curl_errorstr);
+               }
+       } else {
                fclose(indexfile);
-               return error("Unable to get pack index %s", url);
+               return error("Unable to start request");
        }
 
        fclose(indexfile);
-       return 0;
+
+       return move_temp_to_file(tmpfile, filename);
 }
 
 static int setup_index(struct alt_base *repo, unsigned char *sha1)
@@ -137,53 +444,86 @@ static int setup_index(struct alt_base *repo, unsigned char *sha1)
        return 0;
 }
 
-static int fetch_alternates(char *base)
+static void process_alternates_response(void *callback_data)
 {
-       int ret = 0;
-       struct buffer buffer;
-       char *url;
+       struct alternates_request *alt_req =
+               (struct alternates_request *)callback_data;
+       struct active_request_slot *slot = alt_req->slot;
+       struct alt_base *tail = alt;
+       char *base = alt_req->base;
+       static const char null_byte = '\0';
        char *data;
        int i = 0;
-       if (got_alternates)
-               return 0;
-       data = xmalloc(4096);
-       buffer.size = 4096;
-       buffer.posn = 0;
-       buffer.buffer = data;
 
-       if (get_verbosely)
-               fprintf(stderr, "Getting alternates list\n");
-       
-       url = xmalloc(strlen(base) + 31);
-       sprintf(url, "%s/objects/info/http-alternates", base);
-
-       curl_easy_setopt(curl, CURLOPT_FILE, &buffer);
-       curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
-       curl_easy_setopt(curl, CURLOPT_URL, url);
-
-       if (curl_easy_perform(curl) || !buffer.posn) {
-               sprintf(url, "%s/objects/info/alternates", base);
-               
-               curl_easy_setopt(curl, CURLOPT_FILE, &buffer);
-               curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
-               curl_easy_setopt(curl, CURLOPT_URL, url);
-               
-               if (curl_easy_perform(curl)) {
-                       return 0;
+       if (alt_req->http_specific) {
+               if (slot->curl_result != CURLE_OK ||
+                   !alt_req->buffer->posn) {
+
+                       /* Try reusing the slot to get non-http alternates */
+                       alt_req->http_specific = 0;
+                       sprintf(alt_req->url, "%s/objects/info/alternates",
+                               base);
+                       curl_easy_setopt(slot->curl, CURLOPT_URL,
+                                        alt_req->url);
+                       active_requests++;
+                       slot->in_use = 1;
+                       if (start_active_slot(slot)) {
+                               return;
+                       } else {
+                               got_alternates = -1;
+                               slot->in_use = 0;
+                               return;
+                       }
+               }
+       } else if (slot->curl_result != CURLE_OK) {
+               if (slot->http_code != 404 &&
+                   slot->curl_result != CURLE_FILE_COULDNT_READ_FILE) {
+                       got_alternates = -1;
+                       return;
                }
        }
 
-       while (i < buffer.posn) {
+       fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
+       alt_req->buffer->posn--;
+       data = alt_req->buffer->buffer;
+
+       while (i < alt_req->buffer->posn) {
                int posn = i;
-               while (posn < buffer.posn && data[posn] != '\n')
+               while (posn < alt_req->buffer->posn && data[posn] != '\n')
                        posn++;
                if (data[posn] == '\n') {
+                       int okay = 0;
+                       int serverlen = 0;
+                       struct alt_base *newalt;
+                       char *target = NULL;
                        if (data[i] == '/') {
-                               int serverlen = strchr(base + 8, '/') - base;
-                               // skip 'objects' at end
-                               char *target = 
-                                       xmalloc(serverlen + posn - i - 6);
-                               struct alt_base *newalt;
+                               serverlen = strchr(base + 8, '/') - base;
+                               okay = 1;
+                       } else if (!memcmp(data + i, "../", 3)) {
+                               i += 3;
+                               serverlen = strlen(base);
+                               while (i + 2 < posn && 
+                                      !memcmp(data + i, "../", 3)) {
+                                       do {
+                                               serverlen--;
+                                       } while (serverlen &&
+                                                base[serverlen - 1] != '/');
+                                       i += 3;
+                               }
+                               // If the server got removed, give up.
+                               okay = strchr(base, ':') - base + 3 < 
+                                       serverlen;
+                       } else if (alt_req->http_specific) {
+                               char *colon = strchr(data + i, ':');
+                               char *slash = strchr(data + i, '/');
+                               if (colon && slash && colon < data + posn &&
+                                   slash < data + posn && colon < slash) {
+                                       okay = 1;
+                               }
+                       }
+                       // skip 'objects' at end
+                       if (okay) {
+                               target = xmalloc(serverlen + posn - i - 6);
                                strncpy(target, base, serverlen);
                                strncpy(target + serverlen, data + i,
                                        posn - i - 7);
@@ -192,19 +532,79 @@ static int fetch_alternates(char *base)
                                        fprintf(stderr, 
                                                "Also look at %s\n", target);
                                newalt = xmalloc(sizeof(*newalt));
-                               newalt->next = alt;
+                               newalt->next = NULL;
                                newalt->base = target;
                                newalt->got_indices = 0;
                                newalt->packs = NULL;
-                               alt = newalt;
-                               ret++;
+                               while (tail->next != NULL)
+                                       tail = tail->next;
+                               tail->next = newalt;
                        }
                }
                i = posn + 1;
        }
+
        got_alternates = 1;
+}
+
+static void fetch_alternates(char *base)
+{
+       struct buffer buffer;
+       char *url;
+       char *data;
+       struct active_request_slot *slot;
+       static struct alternates_request alt_req;
+
+       /* If another request has already started fetching alternates,
+          wait for them to arrive and return to processing this request's
+          curl message */
+#ifdef USE_CURL_MULTI
+       while (got_alternates == 0) {
+               step_active_slots();
+       }
+#endif
+
+       /* Nothing to do if they've already been fetched */
+       if (got_alternates == 1)
+               return;
+
+       /* Start the fetch */
+       got_alternates = 0;
+
+       data = xmalloc(4096);
+       buffer.size = 4096;
+       buffer.posn = 0;
+       buffer.buffer = data;
+
+       if (get_verbosely)
+               fprintf(stderr, "Getting alternates list for %s\n", base);
        
-       return ret;
+       url = xmalloc(strlen(base) + 31);
+       sprintf(url, "%s/objects/info/http-alternates", base);
+
+       /* Use a callback to process the result, since another request
+          may fail and need to have alternates loaded before continuing */
+       slot = get_active_slot();
+       slot->callback_func = process_alternates_response;
+       slot->callback_data = &alt_req;
+
+       curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
+       curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
+       curl_easy_setopt(slot->curl, CURLOPT_URL, url);
+
+       alt_req.base = base;
+       alt_req.url = url;
+       alt_req.buffer = &buffer;
+       alt_req.http_specific = 1;
+       alt_req.slot = slot;
+
+       if (start_active_slot(slot))
+               run_active_slot(slot);
+       else
+               got_alternates = -1;
+
+       free(data);
+       free(url);
 }
 
 static int fetch_indices(struct alt_base *repo)
@@ -215,6 +615,8 @@ static int fetch_indices(struct alt_base *repo)
        char *data;
        int i = 0;
 
+       struct active_request_slot *slot;
+
        if (repo->got_indices)
                return 0;
 
@@ -224,25 +626,42 @@ static int fetch_indices(struct alt_base *repo)
        buffer.buffer = data;
 
        if (get_verbosely)
-               fprintf(stderr, "Getting pack list\n");
+               fprintf(stderr, "Getting pack list for %s\n", repo->base);
        
        url = xmalloc(strlen(repo->base) + 21);
        sprintf(url, "%s/objects/info/packs", repo->base);
 
-       curl_easy_setopt(curl, CURLOPT_FILE, &buffer);
-       curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
-       curl_easy_setopt(curl, CURLOPT_URL, url);
-       curl_easy_setopt(curl, CURLOPT_HTTPHEADER, NULL);
-       
-       if (curl_easy_perform(curl)) {
-               return error("Unable to get pack index %s", url);
+       slot = get_active_slot();
+       curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
+       curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
+       curl_easy_setopt(slot->curl, CURLOPT_URL, url);
+       curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
+       if (start_active_slot(slot)) {
+               run_active_slot(slot);
+               if (slot->curl_result != CURLE_OK) {
+                       if (slot->http_code == 404 ||
+                           slot->curl_result == CURLE_FILE_COULDNT_READ_FILE) {
+                               repo->got_indices = 1;
+                               free(buffer.buffer);
+                               return 0;
+                       } else {
+                               repo->got_indices = 0;
+                               free(buffer.buffer);
+                               return error("%s", curl_errorstr);
+                       }
+               }
+       } else {
+               repo->got_indices = 0;
+               free(buffer.buffer);
+               return error("Unable to start request");
        }
 
+       data = buffer.buffer;
        while (i < buffer.posn) {
                switch (data[i]) {
                case 'P':
                        i++;
-                       if (i + 52 < buffer.posn &&
+                       if (i + 52 <= buffer.posn &&
                            !strncmp(data + i, " pack-", 6) &&
                            !strncmp(data + i + 46, ".pack\n", 6)) {
                                get_sha1_hex(data + i + 6, sha1);
@@ -251,12 +670,13 @@ static int fetch_indices(struct alt_base *repo)
                                break;
                        }
                default:
-                       while (data[i] != '\n')
+                       while (i < buffer.posn && data[i] != '\n')
                                i++;
                }
                i++;
        }
 
+       free(buffer.buffer);
        repo->got_indices = 1;
        return 0;
 }
@@ -268,6 +688,13 @@ static int fetch_pack(struct alt_base *repo, unsigned char *sha1)
        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;
 
        if (fetch_indices(repo))
                return -1;
@@ -287,134 +714,205 @@ static int fetch_pack(struct alt_base *repo, unsigned char *sha1)
                repo->base, sha1_to_hex(target->sha1));
 
        filename = sha1_pack_name(target->sha1);
-       packfile = fopen(filename, "w");
+       snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
+       packfile = fopen(tmpfile, "a");
        if (!packfile)
                return error("Unable to open local file %s for pack",
                             filename);
 
-       curl_easy_setopt(curl, CURLOPT_FILE, packfile);
-       curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fwrite);
-       curl_easy_setopt(curl, CURLOPT_URL, url);
-       curl_easy_setopt(curl, CURLOPT_HTTPHEADER, no_pragma_header);
-       
-       if (curl_easy_perform(curl)) {
+       slot = get_active_slot();
+       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 (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 (slot->curl_result != CURLE_OK) {
+                       fclose(packfile);
+                       return error("Unable to get pack file %s\n%s", url,
+                                    curl_errorstr);
+               }
+       } else {
                fclose(packfile);
-               return error("Unable to get pack file %s", url);
+               return error("Unable to start request");
        }
 
        fclose(packfile);
 
+       ret = move_temp_to_file(tmpfile, filename);
+       if (ret)
+               return ret;
+
        lst = &repo->packs;
        while (*lst != target)
                lst = &((*lst)->next);
        *lst = (*lst)->next;
 
+       if (verify_pack(target, 0))
+               return -1;
        install_packed_git(target);
 
        return 0;
 }
 
-int fetch_object(struct alt_base *repo, unsigned char *sha1)
+static int fetch_object(struct alt_base *repo, unsigned char *sha1)
 {
        char *hex = sha1_to_hex(sha1);
-       char *filename = sha1_file_name(sha1);
-       unsigned char real_sha1[20];
-       char *url;
-       char *posn;
-
-       local = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
-
-       if (local < 0)
-               return error("Couldn't open local object %s\n", filename);
-
-       memset(&stream, 0, sizeof(stream));
-
-       inflateInit(&stream);
-
-       SHA1_Init(&c);
+       int ret = 0;
+       struct object_request *obj_req = object_queue_head;
 
-       curl_easy_setopt(curl, CURLOPT_FAILONERROR, 1);
-       curl_easy_setopt(curl, CURLOPT_FILE, NULL);
-       curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
-       curl_easy_setopt(curl, CURLOPT_HTTPHEADER, no_pragma_header);
+       while (obj_req != NULL && memcmp(obj_req->sha1, sha1, 20))
+               obj_req = obj_req->next;
+       if (obj_req == NULL)
+               return error("Couldn't find request for %s in the queue", hex);
 
-       url = xmalloc(strlen(repo->base) + 50);
-       strcpy(url, repo->base);
-       posn = url + strlen(repo->base);
-       strcpy(posn, "objects/");
-       posn += 8;
-       memcpy(posn, hex, 2);
-       posn += 2;
-       *(posn++) = '/';
-       strcpy(posn, hex + 2);
-
-       curl_easy_setopt(curl, CURLOPT_URL, url);
+       if (has_sha1_file(obj_req->sha1)) {
+               release_object_request(obj_req);
+               return 0;
+       }
 
-       if (curl_easy_perform(curl)) {
-               unlink(filename);
-               return -1;
+#ifdef USE_CURL_MULTI
+       while (obj_req->state == WAITING) {
+               step_active_slots();
        }
+#else
+       start_object_request(obj_req);
+#endif
 
-       close(local);
-       inflateEnd(&stream);
-       SHA1_Final(real_sha1, &c);
-       if (zret != Z_STREAM_END) {
-               unlink(filename);
-               return error("File %s (%s) corrupt\n", hex, url);
+       while (obj_req->state == ACTIVE) {
+               run_active_slot(obj_req->slot);
        }
-       if (memcmp(sha1, real_sha1, 20)) {
-               unlink(filename);
-               return error("File %s has bad hash\n", hex);
+       if (obj_req->local != -1) {
+               close(obj_req->local); obj_req->local = -1;
        }
-       
-       pull_say("got %s\n", hex);
-       return 0;
+
+       if (obj_req->state == ABORTED) {
+               ret = error("Request for %s aborted", hex);
+       } else if (obj_req->curl_result != CURLE_OK &&
+                  obj_req->http_code != 416) {
+               if (obj_req->http_code == 404 ||
+                   obj_req->curl_result == CURLE_FILE_COULDNT_READ_FILE)
+                       ret = -1; /* Be silent, it is probably in a pack. */
+               else
+                       ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
+                                   obj_req->errorstr, obj_req->curl_result,
+                                   obj_req->http_code, hex);
+       } else if (obj_req->zret != Z_STREAM_END) {
+               ret = error("File %s (%s) corrupt\n", hex, obj_req->url);
+       } else if (memcmp(obj_req->sha1, obj_req->real_sha1, 20)) {
+               ret = error("File %s has bad hash\n", hex);
+       } else if (obj_req->rename < 0) {
+               ret = error("unable to write sha1 filename %s: %s",
+                           obj_req->filename,
+                           strerror(obj_req->rename));
+       }
+
+       release_object_request(obj_req);
+       return ret;
 }
 
 int fetch(unsigned char *sha1)
 {
        struct alt_base *altbase = alt;
+
+       if (!fetch_object(altbase, sha1))
+               return 0;
        while (altbase) {
-               if (!fetch_object(altbase, sha1))
-                       return 0;
                if (!fetch_pack(altbase, sha1))
                        return 0;
-               if (fetch_alternates(altbase->base) > 0) {
-                       altbase = alt;
-                       continue;
-               }
+               fetch_alternates(alt->base);
                altbase = altbase->next;
        }
        return error("Unable to find %s under %s\n", sha1_to_hex(sha1), 
-                    initial_base);
+                    alt->base);
+}
+
+static inline int needs_quote(int ch)
+{
+       switch (ch) {
+       case '/': case '-': case '.':
+       case 'A'...'Z': case 'a'...'z': case '0'...'9':
+               return 0;
+       default:
+               return 1;
+       }
+}
+
+static inline int hex(int v)
+{
+       if (v < 10) return '0' + v;
+       else return 'A' + v - 10;
+}
+
+static char *quote_ref_url(const char *base, const char *ref)
+{
+       const char *cp;
+       char *dp, *qref;
+       int len, baselen, ch;
+
+       baselen = strlen(base);
+       len = baselen + 6; /* "refs/" + NUL */
+       for (cp = ref; (ch = *cp) != 0; cp++, len++)
+               if (needs_quote(ch))
+                       len += 2; /* extra two hex plus replacement % */
+       qref = xmalloc(len);
+       memcpy(qref, base, baselen);
+       memcpy(qref + baselen, "refs/", 5);
+       for (cp = ref, dp = qref + baselen + 5; (ch = *cp) != 0; cp++) {
+               if (needs_quote(ch)) {
+                       *dp++ = '%';
+                       *dp++ = hex((ch >> 4) & 0xF);
+                       *dp++ = hex(ch & 0xF);
+               }
+               else
+                       *dp++ = ch;
+       }
+       *dp = 0;
+
+       return qref;
 }
 
 int fetch_ref(char *ref, unsigned char *sha1)
 {
-        char *url, *posn;
+        char *url;
         char hex[42];
         struct buffer buffer;
-       char *base = initial_base;
+       char *base = alt->base;
+       struct active_request_slot *slot;
         buffer.size = 41;
         buffer.posn = 0;
         buffer.buffer = hex;
         hex[41] = '\0';
         
-        curl_easy_setopt(curl, CURLOPT_FILE, &buffer);
-        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
-       curl_easy_setopt(curl, CURLOPT_HTTPHEADER, NULL);
-
-        url = xmalloc(strlen(base) + 6 + strlen(ref));
-        strcpy(url, base);
-        posn = url + strlen(base);
-        strcpy(posn, "refs/");
-        posn += 5;
-        strcpy(posn, ref);
-
-        curl_easy_setopt(curl, CURLOPT_URL, url);
-
-        if (curl_easy_perform(curl))
-                return error("Couldn't get %s for %s\n", url, ref);
+       url = quote_ref_url(base, ref);
+       slot = get_active_slot();
+       curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
+       curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
+       curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, NULL);
+       curl_easy_setopt(slot->curl, CURLOPT_URL, url);
+       if (start_active_slot(slot)) {
+               run_active_slot(slot);
+               if (slot->curl_result != CURLE_OK)
+                       return error("Couldn't get %s for %s\n%s",
+                                    url, ref, curl_errorstr);
+       } else {
+               return error("Unable to start request");
+       }
 
         hex[40] = '\0';
         get_sha1_hex(hex, sha1);
@@ -426,6 +924,9 @@ int main(int argc, char **argv)
        char *commit_id;
        char *url;
        int arg = 1;
+       int rc = 0;
+
+       setup_git_directory();
 
        while (arg < argc && argv[arg][0] == '-') {
                if (argv[arg][1] == 't') {
@@ -441,6 +942,8 @@ int main(int argc, char **argv)
                } else if (argv[arg][1] == 'w') {
                        write_ref = argv[arg + 1];
                        arg++;
+               } else if (!strcmp(argv[arg], "--recover")) {
+                       get_recover = 1;
                }
                arg++;
        }
@@ -451,28 +954,22 @@ int main(int argc, char **argv)
        commit_id = argv[arg];
        url = argv[arg + 1];
 
-       curl_global_init(CURL_GLOBAL_ALL);
+       http_init();
 
-       curl = curl_easy_init();
        no_pragma_header = curl_slist_append(no_pragma_header, "Pragma:");
 
-       curl_ssl_verify = getenv("GIT_SSL_NO_VERIFY") ? 0 : 1;
-       curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, curl_ssl_verify);
-#if LIBCURL_VERSION_NUM >= 0x070907
-       curl_easy_setopt(curl, CURLOPT_NETRC, CURL_NETRC_OPTIONAL);
-#endif
-
        alt = xmalloc(sizeof(*alt));
        alt->base = url;
        alt->got_indices = 0;
        alt->packs = NULL;
        alt->next = NULL;
-       initial_base = url;
 
        if (pull(commit_id))
-               return 1;
+               rc = 1;
 
        curl_slist_free_all(no_pragma_header);
-       curl_global_cleanup();
-       return 0;
+
+       http_cleanup();
+
+       return rc;
 }