rev-parse lstat() workaround cleanup.
[gitweb.git] / http-fetch.c
index 0aba8917548b3db9a43ce9802caa1c90176c70c1..72edf28b0010ad107bae16a7330bad34f4bb5bca 100644 (file)
@@ -2,37 +2,14 @@
 #include "commit.h"
 #include "pack.h"
 #include "fetch.h"
-
-#include <curl/curl.h>
-#include <curl/easy.h>
-
-#if LIBCURL_VERSION_NUM >= 0x070908
-#define USE_CURL_MULTI
-#define DEFAULT_MAX_REQUESTS 5
-#endif
-
-#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
+#include "http.h"
 
 #define PREV_BUF_SIZE 4096
 #define RANGE_HEADER_SIZE 30
 
-static int active_requests = 0;
-static int data_received;
+static int got_alternates = -1;
 
-#ifdef USE_CURL_MULTI
-static int max_requests = DEFAULT_MAX_REQUESTS;
-static CURLM *curlm;
-#endif
-static CURL *curl_default;
-static struct curl_slist *pragma_header;
 static struct curl_slist *no_pragma_header;
-static struct curl_slist *no_range_header;
-static char curl_errorstr[CURL_ERROR_SIZE];
 
 struct alt_base
 {
@@ -44,14 +21,14 @@ struct alt_base
 
 static struct alt_base *alt = NULL;
 
-enum transfer_state {
+enum object_request_state {
        WAITING,
        ABORTED,
        ACTIVE,
        COMPLETE,
 };
 
-struct transfer_request
+struct object_request
 {
        unsigned char sha1[20];
        struct alt_base *repo;
@@ -59,7 +36,7 @@ struct transfer_request
        char filename[PATH_MAX];
        char tmpfile[PATH_MAX];
        int local;
-       enum transfer_state state;
+       enum object_request_state state;
        CURLcode curl_result;
        char errorstr[CURL_ERROR_SIZE];
        long http_code;
@@ -69,46 +46,18 @@ struct transfer_request
        int zret;
        int rename;
        struct active_request_slot *slot;
-       struct transfer_request *next;
-};
-
-struct active_request_slot
-{
-       CURL *curl;
-       FILE *local;
-       int in_use;
-       int done;
-       CURLcode curl_result;
-       struct active_request_slot *next;
+       struct object_request *next;
 };
 
-static struct transfer_request *request_queue_head = NULL;
-static struct active_request_slot *active_queue_head = NULL;
-
-static int curl_ssl_verify;
-static char *ssl_cert;
-static char *ssl_key;
-static char *ssl_capath;
-static char *ssl_cainfo;
-
-struct buffer
-{
-        size_t posn;
-        size_t size;
-        void *buffer;
+struct alternates_request {
+       char *base;
+       char *url;
+       struct buffer *buffer;
+       struct active_request_slot *slot;
+       int http_specific;
 };
 
-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;
-       data_received++;
-        return size;
-}
+static struct object_request *object_queue_head = NULL;
 
 static size_t fwrite_sha1_file(void *ptr, size_t eltsize, size_t nmemb,
                               void *data)
@@ -116,148 +65,35 @@ 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 transfer_request *request = (struct transfer_request *)data;
+       struct object_request *obj_req = (struct object_request *)data;
        do {
-               ssize_t retval = write(request->local,
+               ssize_t retval = write(obj_req->local,
                                       ptr + posn, size - posn);
                if (retval < 0)
                        return posn;
                posn += retval;
        } while (posn < size);
 
-       request->stream.avail_in = size;
-       request->stream.next_in = ptr;
+       obj_req->stream.avail_in = size;
+       obj_req->stream.next_in = ptr;
        do {
-               request->stream.next_out = expn;
-               request->stream.avail_out = sizeof(expn);
-               request->zret = inflate(&request->stream, Z_SYNC_FLUSH);
-               SHA1_Update(&request->c, expn,
-                           sizeof(expn) - request->stream.avail_out);
-       } while (request->stream.avail_in && request->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;
 }
 
-#ifdef USE_CURL_MULTI
-void process_curl_messages();
-void process_request_queue();
-#endif
-
-struct active_request_slot *get_active_slot()
-{
-       struct active_request_slot *slot = active_queue_head;
-       struct active_request_slot *newslot;
-
-#ifdef USE_CURL_MULTI
-       int num_transfers;
-
-       /* Wait for a slot to open up if the queue is full */
-       while (active_requests >= max_requests) {
-               curl_multi_perform(curlm, &num_transfers);
-               if (num_transfers < active_requests) {
-                       process_curl_messages();
-               }
-       }
-#endif
-
-       while (slot != NULL && slot->in_use) {
-               slot = slot->next;
-       }
-       if (slot == NULL) {
-               newslot = xmalloc(sizeof(*newslot));
-               newslot->curl = curl_easy_duphandle(curl_default);
-               newslot->in_use = 0;
-               newslot->next = NULL;
-
-               slot = active_queue_head;
-               if (slot == NULL) {
-                       active_queue_head = newslot;
-               } else {
-                       while (slot->next != NULL) {
-                               slot = slot->next;
-                       }
-                       slot->next = newslot;
-               }
-               slot = newslot;
-       }
-
-       active_requests++;
-       slot->in_use = 1;
-       slot->done = 0;
-       slot->local = NULL;
-       curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, pragma_header);
-       curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, no_range_header);
-       curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, curl_errorstr);
-
-       return slot;
-}
-
-int start_active_slot(struct active_request_slot *slot)
-{
-#ifdef USE_CURL_MULTI
-       CURLMcode curlm_result = curl_multi_add_handle(curlm, slot->curl);
-
-       if (curlm_result != CURLM_OK &&
-           curlm_result != CURLM_CALL_MULTI_PERFORM) {
-               active_requests--;
-               slot->in_use = 0;
-               return 0;
-       }
-#endif
-       return 1;
-}
-
-void run_active_slot(struct active_request_slot *slot)
-{
-#ifdef USE_CURL_MULTI
-       int num_transfers;
-       long last_pos = 0;
-       long current_pos;
-       fd_set readfds;
-       fd_set writefds;
-       fd_set excfds;
-       int max_fd;
-       struct timeval select_timeout;
-       CURLMcode curlm_result;
-
-       while (!slot->done) {
-               data_received = 0;
-               do {
-                       curlm_result = curl_multi_perform(curlm,
-                                                         &num_transfers);
-               } while (curlm_result == CURLM_CALL_MULTI_PERFORM);
-               if (num_transfers < active_requests) {
-                       process_curl_messages();
-                       process_request_queue();
-               }
-
-               if (!data_received && slot->local != NULL) {
-                       current_pos = ftell(slot->local);
-                       if (current_pos > last_pos)
-                               data_received++;
-                       last_pos = current_pos;
-               }
+static void fetch_alternates(char *base);
 
-               if (!slot->done && !data_received) {
-                       max_fd = 0;
-                       FD_ZERO(&readfds);
-                       FD_ZERO(&writefds);
-                       FD_ZERO(&excfds);
-                       select_timeout.tv_sec = 0;
-                       select_timeout.tv_usec = 50000;
-                       select(max_fd, &readfds, &writefds,
-                              &excfds, &select_timeout);
-               }
-       }
-#else
-       slot->curl_result = curl_easy_perform(slot->curl);
-       active_requests--;
-#endif
-}
+static void process_object_response(void *callback_data);
 
-void start_request(struct transfer_request *request)
+static void start_object_request(struct object_request *obj_req)
 {
-       char *hex = sha1_to_hex(request->sha1);
+       char *hex = sha1_to_hex(obj_req->sha1);
        char prevfile[PATH_MAX];
        char *url;
        char *posn;
@@ -269,51 +105,53 @@ void start_request(struct transfer_request *request)
        struct curl_slist *range_header = NULL;
        struct active_request_slot *slot;
 
-       snprintf(prevfile, sizeof(prevfile), "%s.prev", request->filename);
+       snprintf(prevfile, sizeof(prevfile), "%s.prev", obj_req->filename);
        unlink(prevfile);
-       rename(request->tmpfile, prevfile);
-       unlink(request->tmpfile);
+       rename(obj_req->tmpfile, prevfile);
+       unlink(obj_req->tmpfile);
 
-       request->local = open(request->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 (request->local < 0 && errno == ENOENT) {
-               char *dir = strrchr(request->tmpfile, '/');
+       if (obj_req->local < 0 && errno == ENOENT) {
+               char *dir = strrchr(obj_req->tmpfile, '/');
                if (dir) {
                        *dir = 0;
-                       mkdir(request->tmpfile, 0777);
+                       mkdir(obj_req->tmpfile, 0777);
                        *dir = '/';
                }
-               request->local = open(request->tmpfile,
+               obj_req->local = open(obj_req->tmpfile,
                                      O_WRONLY | O_CREAT | O_EXCL, 0666);
        }
 
-       if (request->local < 0) {
-               request->state = ABORTED;
+       if (obj_req->local < 0) {
+               obj_req->state = ABORTED;
                error("Couldn't create temporary file %s for %s: %s\n",
-                     request->tmpfile, request->filename, strerror(errno));
+                     obj_req->tmpfile, obj_req->filename, strerror(errno));
                return;
        }
 
-       memset(&request->stream, 0, sizeof(request->stream));
+       memset(&obj_req->stream, 0, sizeof(obj_req->stream));
 
-       inflateInit(&request->stream);
+       inflateInit(&obj_req->stream);
 
-       SHA1_Init(&request->c);
+       SHA1_Init(&obj_req->c);
 
-       url = xmalloc(strlen(request->repo->base) + 50);
-       request->url = xmalloc(strlen(request->repo->base) + 50);
-       strcpy(url, request->repo->base);
-       posn = url + strlen(request->repo->base);
+       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(request->url, url);
+       strcpy(obj_req->url, url);
 
        /* If a previous temp file is present, process what was already
           fetched. */
@@ -325,7 +163,7 @@ void start_request(struct transfer_request *request)
                                if (fwrite_sha1_file(prev_buf,
                                                     1,
                                                     prev_read,
-                                                    request) == prev_read) {
+                                                    obj_req) == prev_read) {
                                        prev_posn += prev_read;
                                } else {
                                        prev_read = -1;
@@ -339,20 +177,24 @@ void start_request(struct transfer_request *request)
        /* 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(&request->stream, 0, sizeof(request->stream));
-               inflateInit(&request->stream);
-               SHA1_Init(&request->c);
+               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(request->local, SEEK_SET, 0);
-                       ftruncate(request->local, 0);
+                       lseek(obj_req->local, SEEK_SET, 0);
+                       ftruncate(obj_req->local, 0);
                }
        }
 
        slot = get_active_slot();
-       curl_easy_setopt(slot->curl, CURLOPT_FILE, request);
+       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, request->errorstr);
+       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);
 
@@ -370,137 +212,127 @@ void start_request(struct transfer_request *request)
        }
 
        /* Try to get the request started, abort the request on error */
+       obj_req->state = ACTIVE;
        if (!start_active_slot(slot)) {
-               request->state = ABORTED;
-               close(request->local);
-               free(request->url);
+               obj_req->state = ABORTED;
+               obj_req->slot = NULL;
+               close(obj_req->local); obj_req->local = -1;
+               free(obj_req->url);
                return;
        }
-       
-       request->slot = slot;
-       request->state = ACTIVE;
 }
 
-void finish_request(struct transfer_request *request)
+static void finish_object_request(struct object_request *obj_req)
 {
-       fchmod(request->local, 0444);
-       close(request->local);
+       struct stat st;
+
+       fchmod(obj_req->local, 0444);
+       close(obj_req->local); obj_req->local = -1;
 
-       if (request->http_code == 416) {
+       if (obj_req->http_code == 416) {
                fprintf(stderr, "Warning: requested range invalid; we may already have all the data.\n");
-       } else if (request->curl_result != CURLE_OK) {
+       } 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(&request->stream);
-       SHA1_Final(request->real_sha1, &request->c);
-       if (request->zret != Z_STREAM_END) {
-               unlink(request->tmpfile);
+       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(request->sha1, request->real_sha1, 20)) {
-               unlink(request->tmpfile);
+       if (memcmp(obj_req->sha1, obj_req->real_sha1, 20)) {
+               unlink(obj_req->tmpfile);
                return;
        }
-       request->rename =
-               move_temp_to_file(request->tmpfile, request->filename);
+       obj_req->rename =
+               move_temp_to_file(obj_req->tmpfile, obj_req->filename);
 
-       if (request->rename == 0)
-               pull_say("got %s\n", sha1_to_hex(request->sha1));
+       if (obj_req->rename == 0)
+               pull_say("got %s\n", sha1_to_hex(obj_req->sha1));
 }
 
-void release_request(struct transfer_request *request)
+static void process_object_response(void *callback_data)
 {
-       struct transfer_request *entry = request_queue_head;
+       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);
+}
 
-       if (request == request_queue_head) {
-               request_queue_head = request->next;
+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 != request)
+               while (entry->next != NULL && entry->next != obj_req)
                        entry = entry->next;
-               if (entry->next == request)
+               if (entry->next == obj_req)
                        entry->next = entry->next->next;
        }
 
-       free(request->url);
-       free(request);
+       free(obj_req->url);
+       free(obj_req);
 }
 
 #ifdef USE_CURL_MULTI
-void process_curl_messages()
-{
-       int num_messages;
-       struct active_request_slot *slot;
-       struct transfer_request *request = NULL;
-       CURLMsg *curl_message = curl_multi_info_read(curlm, &num_messages);
-
-       while (curl_message != NULL) {
-               if (curl_message->msg == CURLMSG_DONE) {
-                       slot = active_queue_head;
-                       while (slot != NULL &&
-                              slot->curl != curl_message->easy_handle)
-                               slot = slot->next;
-                       if (slot != NULL) {
-                               curl_multi_remove_handle(curlm, slot->curl);
-                               active_requests--;
-                               slot->done = 1;
-                               slot->in_use = 0;
-                               slot->curl_result = curl_message->data.result;
-                               request = request_queue_head;
-                               while (request != NULL &&
-                                      request->slot != slot)
-                                       request = request->next;
-                       } else {
-                               fprintf(stderr, "Received DONE message for unknown request!\n");
-                       }
-                       if (request != NULL) {
-                               request->curl_result =
-                                       curl_message->data.result;
-                               curl_easy_getinfo(slot->curl,
-                                                 CURLINFO_HTTP_CODE,
-                                                 &request->http_code);
-                               request->slot = NULL;
-
-                               /* Use alternates if necessary */
-                               if (request->http_code == 404 &&
-                                   request->repo->next != NULL) {
-                                       request->repo = request->repo->next;
-                                       start_request(request);
-                               } else {
-                                       finish_request(request);
-                                       request->state = COMPLETE;
-                               }
-                       }
-               } else {
-                       fprintf(stderr, "Unknown CURL message received: %d\n",
-                               (int)curl_message->msg);
-               }
-               curl_message = curl_multi_info_read(curlm, &num_messages);
-       }
-}
-
-void process_request_queue()
+void fill_active_slots(void)
 {
-       struct transfer_request *request = request_queue_head;
+       struct object_request *obj_req = object_queue_head;
+       struct active_request_slot *slot = active_queue_head;
        int num_transfers;
 
-       while (active_requests < max_requests && request != NULL) {
-               if (request->state == WAITING) {
-                       if (has_sha1_file(request->sha1))
-                               release_request(request);
+       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_request(request);
+                               start_object_request(obj_req);
                        curl_multi_perform(curlm, &num_transfers);
                }
-               request = request->next;
+               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 transfer_request *newreq;
-       struct transfer_request *tail;
+       struct object_request *newreq;
+       struct object_request *tail;
        char *filename = sha1_file_name(sha1);
 
        newreq = xmalloc(sizeof(*newreq));
@@ -514,18 +346,19 @@ void prefetch(unsigned char *sha1)
                 "%s.temp", filename);
        newreq->next = NULL;
 
-       if (request_queue_head == NULL) {
-               request_queue_head = newreq;
+       if (object_queue_head == NULL) {
+               object_queue_head = newreq;
        } else {
-               tail = request_queue_head;
+               tail = object_queue_head;
                while (tail->next != NULL) {
                        tail = tail->next;
                }
                tail->next = newreq;
        }
+
 #ifdef USE_CURL_MULTI
-       process_request_queue();
-       process_curl_messages();
+       fill_active_slots();
+       step_active_slots();
 #endif
 }
 
@@ -541,16 +374,17 @@ static int fetch_index(struct alt_base *repo, unsigned char *sha1)
 
        FILE *indexfile;
        struct active_request_slot *slot;
+       struct slot_results results;
 
        if (has_pack_index(sha1))
                return 0;
 
        if (get_verbosely)
                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, hex);
-       
+
        filename = sha1_pack_index_name(sha1);
        snprintf(tmpfile, sizeof(tmpfile), "%s.temp", filename);
        indexfile = fopen(tmpfile, "a");
@@ -559,6 +393,7 @@ static int fetch_index(struct alt_base *repo, unsigned char *sha1)
                             filename);
 
        slot = get_active_slot();
+       slot->results = &results;
        curl_easy_setopt(slot->curl, CURLOPT_FILE, indexfile);
        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
        curl_easy_setopt(slot->curl, CURLOPT_URL, url);
@@ -580,12 +415,13 @@ static int fetch_index(struct alt_base *repo, unsigned char *sha1)
 
        if (start_active_slot(slot)) {
                run_active_slot(slot);
-               if (slot->curl_result != CURLE_OK) {
+               if (results.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 start request");
        }
 
@@ -609,61 +445,52 @@ 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;
-       int http_specific = 1;
-       struct alt_base *tail = alt;
 
-       struct active_request_slot *slot;
-
-       data = xmalloc(4096);
-       buffer.size = 4095;
-       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);
-
-       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);
-       if (start_active_slot(slot)) {
-               run_active_slot(slot);
-               if (slot->curl_result != CURLE_OK || !buffer.posn) {
-                       http_specific = 0;
-
-                       sprintf(url, "%s/objects/info/alternates", base);
-
-                       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);
+       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)) {
-                               run_active_slot(slot);
-                               if (slot->curl_result != CURLE_OK) {
-                                       return 0;
-                               }
+                               return;
+                       } else {
+                               got_alternates = -1;
+                               slot->in_use = 0;
+                               return;
                        }
                }
-       } else {
-               return 0;
+       } else if (slot->curl_result != CURLE_OK) {
+               if (slot->http_code != 404 &&
+                   slot->curl_result != CURLE_FILE_COULDNT_READ_FILE) {
+                       got_alternates = -1;
+                       return;
+               }
        }
 
-       data[buffer.posn] = '\0';
+       fwrite_buffer(&null_byte, 1, 1, alt_req->buffer);
+       alt_req->buffer->posn--;
+       data = alt_req->buffer->buffer;
 
-       while (i < buffer.posn) {
+       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;
@@ -676,7 +503,7 @@ static int fetch_alternates(char *base)
                        } else if (!memcmp(data + i, "../", 3)) {
                                i += 3;
                                serverlen = strlen(base);
-                               while (i + 2 < posn && 
+                               while (i + 2 < posn &&
                                       !memcmp(data + i, "../", 3)) {
                                        do {
                                                serverlen--;
@@ -685,9 +512,9 @@ static int fetch_alternates(char *base)
                                        i += 3;
                                }
                                // If the server got removed, give up.
-                               okay = strchr(base, ':') - base + 3 < 
+                               okay = strchr(base, ':') - base + 3 <
                                        serverlen;
-                       } else if (http_specific) {
+                       } else if (alt_req->http_specific) {
                                char *colon = strchr(data + i, ':');
                                char *slash = strchr(data + i, '/');
                                if (colon && slash && colon < data + posn &&
@@ -703,7 +530,7 @@ static int fetch_alternates(char *base)
                                        posn - i - 7);
                                target[serverlen + posn - i - 7] = '\0';
                                if (get_verbosely)
-                                       fprintf(stderr, 
+                                       fprintf(stderr,
                                                "Also look at %s\n", target);
                                newalt = xmalloc(sizeof(*newalt));
                                newalt->next = NULL;
@@ -713,13 +540,72 @@ static int fetch_alternates(char *base)
                                while (tail->next != NULL)
                                        tail = tail->next;
                                tail->next = newalt;
-                               ret++;
                        }
                }
                i = posn + 1;
        }
-       
-       return ret;
+
+       got_alternates = 1;
+}
+
+static void fetch_alternates(char *base)
+{
+       struct buffer buffer;
+       char *url;
+       char *data;
+       struct active_request_slot *slot;
+       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);
+
+       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)
@@ -731,6 +617,7 @@ static int fetch_indices(struct alt_base *repo)
        int i = 0;
 
        struct active_request_slot *slot;
+       struct slot_results results;
 
        if (repo->got_indices)
                return 0;
@@ -741,29 +628,43 @@ 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);
 
        slot = get_active_slot();
+       slot->results = &results;
        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)
-                       return error("%s", curl_errorstr);
+               if (results.curl_result != CURLE_OK) {
+                       if (results.http_code == 404 ||
+                           results.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);
@@ -772,12 +673,13 @@ 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;
 }
@@ -796,6 +698,7 @@ static int fetch_pack(struct alt_base *repo, unsigned char *sha1)
        struct curl_slist *range_header = NULL;
 
        struct active_request_slot *slot;
+       struct slot_results results;
 
        if (fetch_indices(repo))
                return -1;
@@ -822,6 +725,7 @@ static int fetch_pack(struct alt_base *repo, unsigned char *sha1)
                             filename);
 
        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);
@@ -843,12 +747,13 @@ static int fetch_pack(struct alt_base *repo, unsigned char *sha1)
 
        if (start_active_slot(slot)) {
                run_active_slot(slot);
-               if (slot->curl_result != CURLE_OK) {
+               if (results.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 start request");
        }
 
@@ -873,85 +778,57 @@ static int fetch_pack(struct alt_base *repo, unsigned char *sha1)
 static int fetch_object(struct alt_base *repo, unsigned char *sha1)
 {
        char *hex = sha1_to_hex(sha1);
-       int ret;
-       struct transfer_request *request = request_queue_head;
+       int ret = 0;
+       struct object_request *obj_req = object_queue_head;
 
-       while (request != NULL && memcmp(request->sha1, sha1, 20))
-               request = request->next;
-       if (request == NULL)
+       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);
 
-       if (has_sha1_file(request->sha1)) {
-               release_request(request);
+       if (has_sha1_file(obj_req->sha1)) {
+               release_object_request(obj_req);
                return 0;
        }
 
 #ifdef USE_CURL_MULTI
-       int num_transfers;
-       while (request->state == WAITING) {
-               curl_multi_perform(curlm, &num_transfers);
-               if (num_transfers < active_requests) {
-                       process_curl_messages();
-                       process_request_queue();
-               }
+       while (obj_req->state == WAITING) {
+               step_active_slots();
        }
 #else
-       start_request(request);
-#endif
-
-       while (request->state == ACTIVE) {
-               run_active_slot(request->slot);
-#ifndef USE_CURL_MULTI
-               request->curl_result = request->slot->curl_result;
-               curl_easy_getinfo(request->slot->curl,
-                                 CURLINFO_HTTP_CODE,
-                                 &request->http_code);
-               request->slot = NULL;
-
-               /* Use alternates if necessary */
-               if (request->http_code == 404 &&
-                   request->repo->next != NULL) {
-                       request->repo = request->repo->next;
-                       start_request(request);
-               } else {
-                       finish_request(request);
-                       request->state = COMPLETE;
-               }
+       start_object_request(obj_req);
 #endif
-       }
 
-       if (request->state == ABORTED) {
-               release_request(request);
-               return error("Request for %s aborted", hex);
+       while (obj_req->state == ACTIVE) {
+               run_active_slot(obj_req->slot);
        }
-
-       if (request->curl_result != CURLE_OK && request->http_code != 416) {
-               ret = error("%s", request->errorstr);
-               release_request(request);
-               return ret;
+       if (obj_req->local != -1) {
+               close(obj_req->local); obj_req->local = -1;
        }
 
-       if (request->zret != Z_STREAM_END) {
-               ret = error("File %s (%s) corrupt\n", hex, request->url);
-               release_request(request);
-               return ret;
-       }
-
-       if (memcmp(request->sha1, request->real_sha1, 20)) {
-               release_request(request);
-               return error("File %s has bad hash\n", hex);
-       }
-
-       if (request->rename < 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",
-                           request->filename,
-                           strerror(request->rename));
-               release_request(request);
-               return ret;
+                           obj_req->filename,
+                           strerror(obj_req->rename));
        }
 
-       release_request(request);
-       return 0;
+       release_object_request(obj_req);
+       return ret;
 }
 
 int fetch(unsigned char *sha1)
@@ -963,9 +840,10 @@ int fetch(unsigned char *sha1)
        while (altbase) {
                if (!fetch_pack(altbase, sha1))
                        return 0;
+               fetch_alternates(alt->base);
                altbase = altbase->next;
        }
-       return error("Unable to find %s under %s\n", sha1_to_hex(sha1), 
+       return error("Unable to find %s under %s\n", sha1_to_hex(sha1),
                     alt->base);
 }
 
@@ -1021,20 +899,22 @@ int fetch_ref(char *ref, unsigned char *sha1)
         struct buffer buffer;
        char *base = alt->base;
        struct active_request_slot *slot;
+       struct slot_results results;
         buffer.size = 41;
         buffer.posn = 0;
         buffer.buffer = hex;
         hex[41] = '\0';
-        
+
        url = quote_ref_url(base, ref);
        slot = get_active_slot();
+       slot->results = &results;
        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)
+               if (results.curl_result != CURLE_OK)
                        return error("Couldn't get %s for %s\n%s",
                                     url, ref, curl_errorstr);
        } else {
@@ -1051,7 +931,9 @@ int main(int argc, char **argv)
        char *commit_id;
        char *url;
        int arg = 1;
-       struct active_request_slot *slot;
+       int rc = 0;
+
+       setup_git_directory();
 
        while (arg < argc && argv[arg][0] == '-') {
                if (argv[arg][1] == 't') {
@@ -1079,73 +961,22 @@ int main(int argc, char **argv)
        commit_id = argv[arg];
        url = argv[arg + 1];
 
-       curl_global_init(CURL_GLOBAL_ALL);
+       http_init();
 
-#ifdef USE_CURL_MULTI
-       char *http_max_requests = getenv("GIT_HTTP_MAX_REQUESTS");
-       if (http_max_requests != NULL)
-               max_requests = atoi(http_max_requests);
-       if (max_requests < 1)
-               max_requests = DEFAULT_MAX_REQUESTS;
-
-       curlm = curl_multi_init();
-       if (curlm == NULL) {
-               fprintf(stderr, "Error creating curl multi handle.\n");
-               return 1;
-       }
-#endif
-       pragma_header = curl_slist_append(pragma_header, "Pragma: no-cache");
        no_pragma_header = curl_slist_append(no_pragma_header, "Pragma:");
-       no_range_header = curl_slist_append(no_range_header, "Range:");
-
-       curl_default = curl_easy_init();
-
-       curl_ssl_verify = getenv("GIT_SSL_NO_VERIFY") ? 0 : 1;
-       curl_easy_setopt(curl_default, CURLOPT_SSL_VERIFYPEER, curl_ssl_verify);
-#if LIBCURL_VERSION_NUM >= 0x070907
-       curl_easy_setopt(curl_default, CURLOPT_NETRC, CURL_NETRC_OPTIONAL);
-#endif
-
-       if ((ssl_cert = getenv("GIT_SSL_CERT")) != NULL) {
-               curl_easy_setopt(curl_default, CURLOPT_SSLCERT, ssl_cert);
-       }
-#if LIBCURL_VERSION_NUM >= 0x070902
-       if ((ssl_key = getenv("GIT_SSL_KEY")) != NULL) {
-               curl_easy_setopt(curl_default, CURLOPT_SSLKEY, ssl_key);
-       }
-#endif
-#if LIBCURL_VERSION_NUM >= 0x070908
-       if ((ssl_capath = getenv("GIT_SSL_CAPATH")) != NULL) {
-               curl_easy_setopt(curl_default, CURLOPT_CAPATH, ssl_capath);
-       }
-#endif
-       if ((ssl_cainfo = getenv("GIT_SSL_CAINFO")) != NULL) {
-               curl_easy_setopt(curl_default, CURLOPT_CAINFO, ssl_cainfo);
-       }
-       curl_easy_setopt(curl_default, CURLOPT_FAILONERROR, 1);
 
        alt = xmalloc(sizeof(*alt));
        alt->base = url;
        alt->got_indices = 0;
        alt->packs = NULL;
        alt->next = NULL;
-       fetch_alternates(alt->base);
 
        if (pull(commit_id))
-               return 1;
+               rc = 1;
 
-       curl_slist_free_all(pragma_header);
        curl_slist_free_all(no_pragma_header);
-       curl_slist_free_all(no_range_header);
-       curl_easy_cleanup(curl_default);
-       slot = active_queue_head;
-       while (slot != NULL) {
-               curl_easy_cleanup(slot->curl);
-               slot = slot->next;
-       }
-#ifdef USE_CURL_MULTI
-       curl_multi_cleanup(curlm);
-#endif
-       curl_global_cleanup();
-       return 0;
+
+       http_cleanup();
+
+       return rc;
 }