Merge branch 'jx/do-not-crash-receive-pack-wo-head' into maint
authorJunio C Hamano <gitster@pobox.com>
Wed, 19 Aug 2015 21:41:26 +0000 (14:41 -0700)
committerJunio C Hamano <gitster@pobox.com>
Wed, 19 Aug 2015 21:41:26 +0000 (14:41 -0700)
An attempt to delete a ref by pushing into a repositorywhose HEAD
symbolic reference points at an unborn branch that cannot be
created due to ref D/F conflict (e.g. refs/heads/a/b exists, HEAD
points at refs/heads/a) failed.

* jx/do-not-crash-receive-pack-wo-head:
receive-pack: crash when checking with non-exist HEAD

1  2 
builtin/receive-pack.c
diff --combined builtin/receive-pack.c
index 94d05717766151e6b183e2c21d279e72812aeb03,2380127c91db0ff0a6cb56995c03ea9bc0b52c77..04cb5a1a060ae0f26d9d49eb02b57408b9c71929
@@@ -1,5 -1,4 +1,5 @@@
  #include "builtin.h"
 +#include "lockfile.h"
  #include "pack.h"
  #include "refs.h"
  #include "pkt-line.h"
@@@ -16,9 -15,6 +16,9 @@@
  #include "connected.h"
  #include "argv-array.h"
  #include "version.h"
 +#include "tag.h"
 +#include "gpg-interface.h"
 +#include "sigchain.h"
  
  static const char receive_pack_usage[] = "git receive-pack <git-dir>";
  
@@@ -26,8 -22,7 +26,8 @@@ enum deny_action 
        DENY_UNCONFIGURED,
        DENY_IGNORE,
        DENY_WARN,
 -      DENY_REFUSE
 +      DENY_REFUSE,
 +      DENY_UPDATE_INSTEAD
  };
  
  static int deny_deletes;
@@@ -38,38 -33,19 +38,38 @@@ static int receive_fsck_objects = -1
  static int transfer_fsck_objects = -1;
  static int receive_unpack_limit = -1;
  static int transfer_unpack_limit = -1;
 +static int advertise_atomic_push = 1;
  static int unpack_limit = 100;
  static int report_status;
  static int use_sideband;
 +static int use_atomic;
  static int quiet;
  static int prefer_ofs_delta = 1;
  static int auto_update_server_info;
  static int auto_gc = 1;
  static int fix_thin = 1;
 +static int stateless_rpc;
 +static const char *service_dir;
  static const char *head_name;
  static void *head_name_to_free;
  static int sent_capabilities;
  static int shallow_update;
  static const char *alt_shallow_file;
 +static struct strbuf push_cert = STRBUF_INIT;
 +static unsigned char push_cert_sha1[20];
 +static struct signature_check sigcheck;
 +static const char *push_cert_nonce;
 +static const char *cert_nonce_seed;
 +
 +static const char *NONCE_UNSOLICITED = "UNSOLICITED";
 +static const char *NONCE_BAD = "BAD";
 +static const char *NONCE_MISSING = "MISSING";
 +static const char *NONCE_OK = "OK";
 +static const char *NONCE_SLOP = "SLOP";
 +static const char *nonce_status;
 +static long nonce_stamp_slop;
 +static unsigned long nonce_stamp_slop_limit;
 +static struct ref_transaction *transaction;
  
  static enum deny_action parse_deny_action(const char *var, const char *value)
  {
@@@ -80,8 -56,6 +80,8 @@@
                        return DENY_WARN;
                if (!strcasecmp(value, "refuse"))
                        return DENY_REFUSE;
 +              if (!strcasecmp(value, "updateinstead"))
 +                      return DENY_UPDATE_INSTEAD;
        }
        if (git_config_bool(var, value))
                return DENY_REFUSE;
@@@ -155,19 -129,6 +155,19 @@@ static int receive_pack_config(const ch
                return 0;
        }
  
 +      if (strcmp(var, "receive.certnonceseed") == 0)
 +              return git_config_string(&cert_nonce_seed, var, value);
 +
 +      if (strcmp(var, "receive.certnonceslop") == 0) {
 +              nonce_stamp_slop_limit = git_config_ulong(var, value);
 +              return 0;
 +      }
 +
 +      if (strcmp(var, "receive.advertiseatomic") == 0) {
 +              advertise_atomic_push = git_config_bool(var, value);
 +              return 0;
 +      }
 +
        return git_default_config(var, value, cb);
  }
  
@@@ -176,28 -137,18 +176,28 @@@ static void show_ref(const char *path, 
        if (ref_is_hidden(path))
                return;
  
 -      if (sent_capabilities)
 +      if (sent_capabilities) {
                packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
 -      else
 -              packet_write(1, "%s %s%c%s%s agent=%s\n",
 -                           sha1_to_hex(sha1), path, 0,
 -                           " report-status delete-refs side-band-64k quiet",
 -                           prefer_ofs_delta ? " ofs-delta" : "",
 -                           git_user_agent_sanitized());
 -      sent_capabilities = 1;
 +      } else {
 +              struct strbuf cap = STRBUF_INIT;
 +
 +              strbuf_addstr(&cap,
 +                            "report-status delete-refs side-band-64k quiet");
 +              if (advertise_atomic_push)
 +                      strbuf_addstr(&cap, " atomic");
 +              if (prefer_ofs_delta)
 +                      strbuf_addstr(&cap, " ofs-delta");
 +              if (push_cert_nonce)
 +                      strbuf_addf(&cap, " push-cert=%s", push_cert_nonce);
 +              strbuf_addf(&cap, " agent=%s", git_user_agent_sanitized());
 +              packet_write(1, "%s %s%c%s\n",
 +                           sha1_to_hex(sha1), path, 0, cap.buf);
 +              strbuf_release(&cap);
 +              sent_capabilities = 1;
 +      }
  }
  
 -static int show_ref_cb(const char *path, const unsigned char *sha1, int flag, void *unused)
 +static int show_ref_cb(const char *path, const struct object_id *oid, int flag, void *unused)
  {
        path = strip_namespace(path);
        /*
         */
        if (!path)
                path = ".have";
 -      show_ref(path, sha1);
 +      show_ref(path, oid->hash);
        return 0;
  }
  
@@@ -228,7 -179,6 +228,7 @@@ static void collect_one_alternate_ref(c
  static void write_head_info(void)
  {
        struct sha1_array sa = SHA1_ARRAY_INIT;
 +
        for_each_alternate_ref(collect_one_alternate_ref, &sa);
        sha1_array_for_each_unique(&sa, show_one_alternate_sha1, NULL);
        sha1_array_clear(&sa);
@@@ -302,231 -252,10 +302,231 @@@ static int copy_to_sideband(int in, in
        return 0;
  }
  
 +#define HMAC_BLOCK_SIZE 64
 +
 +static void hmac_sha1(unsigned char *out,
 +                    const char *key_in, size_t key_len,
 +                    const char *text, size_t text_len)
 +{
 +      unsigned char key[HMAC_BLOCK_SIZE];
 +      unsigned char k_ipad[HMAC_BLOCK_SIZE];
 +      unsigned char k_opad[HMAC_BLOCK_SIZE];
 +      int i;
 +      git_SHA_CTX ctx;
 +
 +      /* RFC 2104 2. (1) */
 +      memset(key, '\0', HMAC_BLOCK_SIZE);
 +      if (HMAC_BLOCK_SIZE < key_len) {
 +              git_SHA1_Init(&ctx);
 +              git_SHA1_Update(&ctx, key_in, key_len);
 +              git_SHA1_Final(key, &ctx);
 +      } else {
 +              memcpy(key, key_in, key_len);
 +      }
 +
 +      /* RFC 2104 2. (2) & (5) */
 +      for (i = 0; i < sizeof(key); i++) {
 +              k_ipad[i] = key[i] ^ 0x36;
 +              k_opad[i] = key[i] ^ 0x5c;
 +      }
 +
 +      /* RFC 2104 2. (3) & (4) */
 +      git_SHA1_Init(&ctx);
 +      git_SHA1_Update(&ctx, k_ipad, sizeof(k_ipad));
 +      git_SHA1_Update(&ctx, text, text_len);
 +      git_SHA1_Final(out, &ctx);
 +
 +      /* RFC 2104 2. (6) & (7) */
 +      git_SHA1_Init(&ctx);
 +      git_SHA1_Update(&ctx, k_opad, sizeof(k_opad));
 +      git_SHA1_Update(&ctx, out, 20);
 +      git_SHA1_Final(out, &ctx);
 +}
 +
 +static char *prepare_push_cert_nonce(const char *path, unsigned long stamp)
 +{
 +      struct strbuf buf = STRBUF_INIT;
 +      unsigned char sha1[20];
 +
 +      strbuf_addf(&buf, "%s:%lu", path, stamp);
 +      hmac_sha1(sha1, buf.buf, buf.len, cert_nonce_seed, strlen(cert_nonce_seed));;
 +      strbuf_release(&buf);
 +
 +      /* RFC 2104 5. HMAC-SHA1-80 */
 +      strbuf_addf(&buf, "%lu-%.*s", stamp, 20, sha1_to_hex(sha1));
 +      return strbuf_detach(&buf, NULL);
 +}
 +
 +/*
 + * NEEDSWORK: reuse find_commit_header() from jk/commit-author-parsing
 + * after dropping "_commit" from its name and possibly moving it out
 + * of commit.c
 + */
 +static char *find_header(const char *msg, size_t len, const char *key)
 +{
 +      int key_len = strlen(key);
 +      const char *line = msg;
 +
 +      while (line && line < msg + len) {
 +              const char *eol = strchrnul(line, '\n');
 +
 +              if ((msg + len <= eol) || line == eol)
 +                      return NULL;
 +              if (line + key_len < eol &&
 +                  !memcmp(line, key, key_len) && line[key_len] == ' ') {
 +                      int offset = key_len + 1;
 +                      return xmemdupz(line + offset, (eol - line) - offset);
 +              }
 +              line = *eol ? eol + 1 : NULL;
 +      }
 +      return NULL;
 +}
 +
 +static const char *check_nonce(const char *buf, size_t len)
 +{
 +      char *nonce = find_header(buf, len, "nonce");
 +      unsigned long stamp, ostamp;
 +      char *bohmac, *expect = NULL;
 +      const char *retval = NONCE_BAD;
 +
 +      if (!nonce) {
 +              retval = NONCE_MISSING;
 +              goto leave;
 +      } else if (!push_cert_nonce) {
 +              retval = NONCE_UNSOLICITED;
 +              goto leave;
 +      } else if (!strcmp(push_cert_nonce, nonce)) {
 +              retval = NONCE_OK;
 +              goto leave;
 +      }
 +
 +      if (!stateless_rpc) {
 +              /* returned nonce MUST match what we gave out earlier */
 +              retval = NONCE_BAD;
 +              goto leave;
 +      }
 +
 +      /*
 +       * In stateless mode, we may be receiving a nonce issued by
 +       * another instance of the server that serving the same
 +       * repository, and the timestamps may not match, but the
 +       * nonce-seed and dir should match, so we can recompute and
 +       * report the time slop.
 +       *
 +       * In addition, when a nonce issued by another instance has
 +       * timestamp within receive.certnonceslop seconds, we pretend
 +       * as if we issued that nonce when reporting to the hook.
 +       */
 +
 +      /* nonce is concat(<seconds-since-epoch>, "-", <hmac>) */
 +      if (*nonce <= '0' || '9' < *nonce) {
 +              retval = NONCE_BAD;
 +              goto leave;
 +      }
 +      stamp = strtoul(nonce, &bohmac, 10);
 +      if (bohmac == nonce || bohmac[0] != '-') {
 +              retval = NONCE_BAD;
 +              goto leave;
 +      }
 +
 +      expect = prepare_push_cert_nonce(service_dir, stamp);
 +      if (strcmp(expect, nonce)) {
 +              /* Not what we would have signed earlier */
 +              retval = NONCE_BAD;
 +              goto leave;
 +      }
 +
 +      /*
 +       * By how many seconds is this nonce stale?  Negative value
 +       * would mean it was issued by another server with its clock
 +       * skewed in the future.
 +       */
 +      ostamp = strtoul(push_cert_nonce, NULL, 10);
 +      nonce_stamp_slop = (long)ostamp - (long)stamp;
 +
 +      if (nonce_stamp_slop_limit &&
 +          labs(nonce_stamp_slop) <= nonce_stamp_slop_limit) {
 +              /*
 +               * Pretend as if the received nonce (which passes the
 +               * HMAC check, so it is not a forged by third-party)
 +               * is what we issued.
 +               */
 +              free((void *)push_cert_nonce);
 +              push_cert_nonce = xstrdup(nonce);
 +              retval = NONCE_OK;
 +      } else {
 +              retval = NONCE_SLOP;
 +      }
 +
 +leave:
 +      free(nonce);
 +      free(expect);
 +      return retval;
 +}
 +
 +static void prepare_push_cert_sha1(struct child_process *proc)
 +{
 +      static int already_done;
 +
 +      if (!push_cert.len)
 +              return;
 +
 +      if (!already_done) {
 +              struct strbuf gpg_output = STRBUF_INIT;
 +              struct strbuf gpg_status = STRBUF_INIT;
 +              int bogs /* beginning_of_gpg_sig */;
 +
 +              already_done = 1;
 +              if (write_sha1_file(push_cert.buf, push_cert.len, "blob", push_cert_sha1))
 +                      hashclr(push_cert_sha1);
 +
 +              memset(&sigcheck, '\0', sizeof(sigcheck));
 +              sigcheck.result = 'N';
 +
 +              bogs = parse_signature(push_cert.buf, push_cert.len);
 +              if (verify_signed_buffer(push_cert.buf, bogs,
 +                                       push_cert.buf + bogs, push_cert.len - bogs,
 +                                       &gpg_output, &gpg_status) < 0) {
 +                      ; /* error running gpg */
 +              } else {
 +                      sigcheck.payload = push_cert.buf;
 +                      sigcheck.gpg_output = gpg_output.buf;
 +                      sigcheck.gpg_status = gpg_status.buf;
 +                      parse_gpg_output(&sigcheck);
 +              }
 +
 +              strbuf_release(&gpg_output);
 +              strbuf_release(&gpg_status);
 +              nonce_status = check_nonce(push_cert.buf, bogs);
 +      }
 +      if (!is_null_sha1(push_cert_sha1)) {
 +              argv_array_pushf(&proc->env_array, "GIT_PUSH_CERT=%s",
 +                               sha1_to_hex(push_cert_sha1));
 +              argv_array_pushf(&proc->env_array, "GIT_PUSH_CERT_SIGNER=%s",
 +                               sigcheck.signer ? sigcheck.signer : "");
 +              argv_array_pushf(&proc->env_array, "GIT_PUSH_CERT_KEY=%s",
 +                               sigcheck.key ? sigcheck.key : "");
 +              argv_array_pushf(&proc->env_array, "GIT_PUSH_CERT_STATUS=%c",
 +                               sigcheck.result);
 +              if (push_cert_nonce) {
 +                      argv_array_pushf(&proc->env_array,
 +                                       "GIT_PUSH_CERT_NONCE=%s",
 +                                       push_cert_nonce);
 +                      argv_array_pushf(&proc->env_array,
 +                                       "GIT_PUSH_CERT_NONCE_STATUS=%s",
 +                                       nonce_status);
 +                      if (nonce_status == NONCE_SLOP)
 +                              argv_array_pushf(&proc->env_array,
 +                                               "GIT_PUSH_CERT_NONCE_SLOP=%ld",
 +                                               nonce_stamp_slop);
 +              }
 +      }
 +}
 +
  typedef int (*feed_fn)(void *, const char **, size_t *);
  static int run_and_feed_hook(const char *hook_name, feed_fn feed, void *feed_state)
  {
 -      struct child_process proc;
 +      struct child_process proc = CHILD_PROCESS_INIT;
        struct async muxer;
        const char *argv[2];
        int code;
  
        argv[1] = NULL;
  
 -      memset(&proc, 0, sizeof(proc));
        proc.argv = argv;
        proc.in = -1;
        proc.stdout_to_stderr = 1;
                proc.err = muxer.in;
        }
  
 +      prepare_push_cert_sha1(&proc);
 +
        code = start_command(&proc);
        if (code) {
                if (use_sideband)
                return code;
        }
  
 +      sigchain_push(SIGPIPE, SIG_IGN);
 +
        while (1) {
                const char *buf;
                size_t n;
        close(proc.in);
        if (use_sideband)
                finish_async(&muxer);
 +
 +      sigchain_pop(SIGPIPE);
 +
        return finish_command(&proc);
  }
  
@@@ -627,7 -350,7 +627,7 @@@ static int run_receive_hook(struct comm
  static int run_update_hook(struct command *cmd)
  {
        const char *argv[5];
 -      struct child_process proc;
 +      struct child_process proc = CHILD_PROCESS_INIT;
        int code;
  
        argv[0] = find_hook("update");
        argv[3] = sha1_to_hex(cmd->new_sha1);
        argv[4] = NULL;
  
 -      memset(&proc, 0, sizeof(proc));
        proc.no_stdin = 1;
        proc.stdout_to_stderr = 1;
        proc.err = use_sideband ? -1 : 0;
@@@ -714,7 -438,7 +714,7 @@@ static int update_shallow_ref(struct co
        uint32_t mask = 1 << (cmd->index % 32);
        int i;
  
 -      trace_printf_key("GIT_TRACE_SHALLOW",
 +      trace_printf_key(&trace_shallow,
                         "shallow: update_shallow_ref %s\n", cmd->ref_name);
        for (i = 0; i < si->shallow->nr; i++)
                if (si->used_shallow[i] &&
        return 0;
  }
  
 +/*
 + * NEEDSWORK: we should consolidate various implementions of "are we
 + * on an unborn branch?" test into one, and make the unified one more
 + * robust. !get_sha1() based check used here and elsewhere would not
 + * allow us to tell an unborn branch from corrupt ref, for example.
 + * For the purpose of fixing "deploy-to-update does not work when
 + * pushing into an empty repository" issue, this should suffice for
 + * now.
 + */
 +static int head_has_history(void)
 +{
 +      unsigned char sha1[20];
 +
 +      return !get_sha1("HEAD", sha1);
 +}
 +
 +static const char *push_to_deploy(unsigned char *sha1,
 +                                struct argv_array *env,
 +                                const char *work_tree)
 +{
 +      const char *update_refresh[] = {
 +              "update-index", "-q", "--ignore-submodules", "--refresh", NULL
 +      };
 +      const char *diff_files[] = {
 +              "diff-files", "--quiet", "--ignore-submodules", "--", NULL
 +      };
 +      const char *diff_index[] = {
 +              "diff-index", "--quiet", "--cached", "--ignore-submodules",
 +              NULL, "--", NULL
 +      };
 +      const char *read_tree[] = {
 +              "read-tree", "-u", "-m", NULL, NULL
 +      };
 +      struct child_process child = CHILD_PROCESS_INIT;
 +
 +      child.argv = update_refresh;
 +      child.env = env->argv;
 +      child.dir = work_tree;
 +      child.no_stdin = 1;
 +      child.stdout_to_stderr = 1;
 +      child.git_cmd = 1;
 +      if (run_command(&child))
 +              return "Up-to-date check failed";
 +
 +      /* run_command() does not clean up completely; reinitialize */
 +      child_process_init(&child);
 +      child.argv = diff_files;
 +      child.env = env->argv;
 +      child.dir = work_tree;
 +      child.no_stdin = 1;
 +      child.stdout_to_stderr = 1;
 +      child.git_cmd = 1;
 +      if (run_command(&child))
 +              return "Working directory has unstaged changes";
 +
 +      /* diff-index with either HEAD or an empty tree */
 +      diff_index[4] = head_has_history() ? "HEAD" : EMPTY_TREE_SHA1_HEX;
 +
 +      child_process_init(&child);
 +      child.argv = diff_index;
 +      child.env = env->argv;
 +      child.no_stdin = 1;
 +      child.no_stdout = 1;
 +      child.stdout_to_stderr = 0;
 +      child.git_cmd = 1;
 +      if (run_command(&child))
 +              return "Working directory has staged changes";
 +
 +      read_tree[3] = sha1_to_hex(sha1);
 +      child_process_init(&child);
 +      child.argv = read_tree;
 +      child.env = env->argv;
 +      child.dir = work_tree;
 +      child.no_stdin = 1;
 +      child.no_stdout = 1;
 +      child.stdout_to_stderr = 0;
 +      child.git_cmd = 1;
 +      if (run_command(&child))
 +              return "Could not update working tree to new HEAD";
 +
 +      return NULL;
 +}
 +
 +static const char *push_to_checkout_hook = "push-to-checkout";
 +
 +static const char *push_to_checkout(unsigned char *sha1,
 +                                  struct argv_array *env,
 +                                  const char *work_tree)
 +{
 +      argv_array_pushf(env, "GIT_WORK_TREE=%s", absolute_path(work_tree));
 +      if (run_hook_le(env->argv, push_to_checkout_hook,
 +                      sha1_to_hex(sha1), NULL))
 +              return "push-to-checkout hook declined";
 +      else
 +              return NULL;
 +}
 +
 +static const char *update_worktree(unsigned char *sha1)
 +{
 +      const char *retval;
 +      const char *work_tree = git_work_tree_cfg ? git_work_tree_cfg : "..";
 +      struct argv_array env = ARGV_ARRAY_INIT;
 +
 +      if (is_bare_repository())
 +              return "denyCurrentBranch = updateInstead needs a worktree";
 +
 +      argv_array_pushf(&env, "GIT_DIR=%s", absolute_path(get_git_dir()));
 +
 +      if (!find_hook(push_to_checkout_hook))
 +              retval = push_to_deploy(sha1, &env, work_tree);
 +      else
 +              retval = push_to_checkout(sha1, &env, work_tree);
 +
 +      argv_array_clear(&env);
 +      return retval;
 +}
 +
  static const char *update(struct command *cmd, struct shallow_info *si)
  {
        const char *name = cmd->ref_name;
        struct strbuf namespaced_name_buf = STRBUF_INIT;
 -      const char *namespaced_name;
 +      const char *namespaced_name, *ret;
        unsigned char *old_sha1 = cmd->old_sha1;
        unsigned char *new_sha1 = cmd->new_sha1;
 -      struct ref_lock *lock;
  
        /* only refs/... are allowed */
        if (!starts_with(name, "refs/") || check_refname_format(name + 5, 0)) {
                        if (deny_current_branch == DENY_UNCONFIGURED)
                                refuse_unconfigured_deny();
                        return "branch is currently checked out";
 +              case DENY_UPDATE_INSTEAD:
 +                      ret = update_worktree(new_sha1);
 +                      if (ret)
 +                              return ret;
 +                      break;
                }
        }
  
                        return "deletion prohibited";
                }
  
-               if (!strcmp(namespaced_name, head_name)) {
+               if (head_name && !strcmp(namespaced_name, head_name)) {
                        switch (deny_delete_current) {
                        case DENY_IGNORE:
                                break;
                                break;
                        case DENY_REFUSE:
                        case DENY_UNCONFIGURED:
 +                      case DENY_UPDATE_INSTEAD:
                                if (deny_delete_current == DENY_UNCONFIGURED)
                                        refuse_unconfigured_deny_delete_current();
                                rp_error("refusing to delete the current branch: %s", name);
                                return "deletion of the current branch prohibited";
 +                      default:
 +                              return "Invalid denyDeleteCurrent setting";
                        }
                }
        }
        }
  
        if (is_null_sha1(new_sha1)) {
 +              struct strbuf err = STRBUF_INIT;
                if (!parse_object(old_sha1)) {
                        old_sha1 = NULL;
                        if (ref_exists(name)) {
                                cmd->did_not_exist = 1;
                        }
                }
 -              if (delete_ref(namespaced_name, old_sha1, 0)) {
 -                      rp_error("failed to delete %s", name);
 +              if (ref_transaction_delete(transaction,
 +                                         namespaced_name,
 +                                         old_sha1,
 +                                         0, "push", &err)) {
 +                      rp_error("%s", err.buf);
 +                      strbuf_release(&err);
                        return "failed to delete";
                }
 +              strbuf_release(&err);
                return NULL; /* good */
        }
        else {
 +              struct strbuf err = STRBUF_INIT;
                if (shallow_update && si->shallow_ref[cmd->index] &&
                    update_shallow_ref(cmd, si))
                        return "shallow error";
  
 -              lock = lock_any_ref_for_update(namespaced_name, old_sha1,
 -                                             0, NULL);
 -              if (!lock) {
 -                      rp_error("failed to lock %s", name);
 -                      return "failed to lock";
 -              }
 -              if (write_ref_sha1(lock, new_sha1, "push")) {
 -                      return "failed to write"; /* error() already called */
 +              if (ref_transaction_update(transaction,
 +                                         namespaced_name,
 +                                         new_sha1, old_sha1,
 +                                         0, "push",
 +                                         &err)) {
 +                      rp_error("%s", err.buf);
 +                      strbuf_release(&err);
 +
 +                      return "failed to update ref";
                }
 +              strbuf_release(&err);
 +
                return NULL; /* good */
        }
  }
@@@ -1008,8 -598,8 +1008,8 @@@ static void run_update_post_hook(struc
        struct command *cmd;
        int argc;
        const char **argv;
 -      struct child_process proc;
 -      char *hook;
 +      struct child_process proc = CHILD_PROCESS_INIT;
 +      const char *hook;
  
        hook = find_hook("post-update");
        for (argc = 0, cmd = commands; cmd; cmd = cmd->next) {
        argv[0] = hook;
  
        for (argc = 1, cmd = commands; cmd; cmd = cmd->next) {
 -              char *p;
                if (cmd->error_string || cmd->did_not_exist)
                        continue;
 -              p = xmalloc(strlen(cmd->ref_name) + 1);
 -              strcpy(p, cmd->ref_name);
 -              argv[argc] = p;
 +              argv[argc] = xstrdup(cmd->ref_name);
                argc++;
        }
        argv[argc] = NULL;
  
 -      memset(&proc, 0, sizeof(proc));
        proc.no_stdin = 1;
        proc.stdout_to_stderr = 1;
        proc.err = use_sideband ? -1 : 0;
@@@ -1054,7 -648,7 +1054,7 @@@ static void check_aliased_update(struc
        int flag;
  
        strbuf_addf(&buf, "%s%s", get_git_namespace(), cmd->ref_name);
 -      dst_name = resolve_ref_unsafe(buf.buf, sha1, 0, &flag);
 +      dst_name = resolve_ref_unsafe(buf.buf, 0, sha1, &flag);
        strbuf_release(&buf);
  
        if (!(flag & REF_ISSYMREF))
@@@ -1104,7 -698,7 +1104,7 @@@ static void check_aliased_updates(struc
                        string_list_append(&ref_list, cmd->ref_name);
                item->util = (void *)cmd;
        }
 -      sort_string_list(&ref_list);
 +      string_list_sort(&ref_list);
  
        for (cmd = commands; cmd; cmd = cmd->next) {
                if (!cmd->error_string)
@@@ -1182,105 -776,11 +1182,105 @@@ static void reject_updates_to_hidden(st
        }
  }
  
 +static int should_process_cmd(struct command *cmd)
 +{
 +      return !cmd->error_string && !cmd->skip_update;
 +}
 +
 +static void warn_if_skipped_connectivity_check(struct command *commands,
 +                                             struct shallow_info *si)
 +{
 +      struct command *cmd;
 +      int checked_connectivity = 1;
 +
 +      for (cmd = commands; cmd; cmd = cmd->next) {
 +              if (should_process_cmd(cmd) && si->shallow_ref[cmd->index]) {
 +                      error("BUG: connectivity check has not been run on ref %s",
 +                            cmd->ref_name);
 +                      checked_connectivity = 0;
 +              }
 +      }
 +      if (!checked_connectivity)
 +              die("BUG: connectivity check skipped???");
 +}
 +
 +static void execute_commands_non_atomic(struct command *commands,
 +                                      struct shallow_info *si)
 +{
 +      struct command *cmd;
 +      struct strbuf err = STRBUF_INIT;
 +
 +      for (cmd = commands; cmd; cmd = cmd->next) {
 +              if (!should_process_cmd(cmd))
 +                      continue;
 +
 +              transaction = ref_transaction_begin(&err);
 +              if (!transaction) {
 +                      rp_error("%s", err.buf);
 +                      strbuf_reset(&err);
 +                      cmd->error_string = "transaction failed to start";
 +                      continue;
 +              }
 +
 +              cmd->error_string = update(cmd, si);
 +
 +              if (!cmd->error_string
 +                  && ref_transaction_commit(transaction, &err)) {
 +                      rp_error("%s", err.buf);
 +                      strbuf_reset(&err);
 +                      cmd->error_string = "failed to update ref";
 +              }
 +              ref_transaction_free(transaction);
 +      }
 +      strbuf_release(&err);
 +}
 +
 +static void execute_commands_atomic(struct command *commands,
 +                                      struct shallow_info *si)
 +{
 +      struct command *cmd;
 +      struct strbuf err = STRBUF_INIT;
 +      const char *reported_error = "atomic push failure";
 +
 +      transaction = ref_transaction_begin(&err);
 +      if (!transaction) {
 +              rp_error("%s", err.buf);
 +              strbuf_reset(&err);
 +              reported_error = "transaction failed to start";
 +              goto failure;
 +      }
 +
 +      for (cmd = commands; cmd; cmd = cmd->next) {
 +              if (!should_process_cmd(cmd))
 +                      continue;
 +
 +              cmd->error_string = update(cmd, si);
 +
 +              if (cmd->error_string)
 +                      goto failure;
 +      }
 +
 +      if (ref_transaction_commit(transaction, &err)) {
 +              rp_error("%s", err.buf);
 +              reported_error = "atomic transaction failed";
 +              goto failure;
 +      }
 +      goto cleanup;
 +
 +failure:
 +      for (cmd = commands; cmd; cmd = cmd->next)
 +              if (!cmd->error_string)
 +                      cmd->error_string = reported_error;
 +
 +cleanup:
 +      ref_transaction_free(transaction);
 +      strbuf_release(&err);
 +}
 +
  static void execute_commands(struct command *commands,
                             const char *unpacker_error,
                             struct shallow_info *si)
  {
 -      int checked_connectivity;
        struct command *cmd;
        unsigned char sha1[20];
        struct iterate_data data;
        check_aliased_updates(commands);
  
        free(head_name_to_free);
 -      head_name = head_name_to_free = resolve_refdup("HEAD", sha1, 0, NULL);
 +      head_name = head_name_to_free = resolve_refdup("HEAD", 0, sha1, NULL);
  
 -      checked_connectivity = 1;
 -      for (cmd = commands; cmd; cmd = cmd->next) {
 -              if (cmd->error_string)
 -                      continue;
 +      if (use_atomic)
 +              execute_commands_atomic(commands, si);
 +      else
 +              execute_commands_non_atomic(commands, si);
  
 -              if (cmd->skip_update)
 -                      continue;
 +      if (shallow_update)
 +              warn_if_skipped_connectivity_check(commands, si);
 +}
  
 -              cmd->error_string = update(cmd, si);
 -              if (shallow_update && !cmd->error_string &&
 -                  si->shallow_ref[cmd->index]) {
 -                      error("BUG: connectivity check has not been run on ref %s",
 -                            cmd->ref_name);
 -                      checked_connectivity = 0;
 -              }
 -      }
 +static struct command **queue_command(struct command **tail,
 +                                    const char *line,
 +                                    int linelen)
 +{
 +      unsigned char old_sha1[20], new_sha1[20];
 +      struct command *cmd;
 +      const char *refname;
 +      int reflen;
 +
 +      if (linelen < 83 ||
 +          line[40] != ' ' ||
 +          line[81] != ' ' ||
 +          get_sha1_hex(line, old_sha1) ||
 +          get_sha1_hex(line + 41, new_sha1))
 +              die("protocol error: expected old/new/ref, got '%s'", line);
 +
 +      refname = line + 82;
 +      reflen = linelen - 82;
 +      cmd = xcalloc(1, sizeof(struct command) + reflen + 1);
 +      hashcpy(cmd->old_sha1, old_sha1);
 +      hashcpy(cmd->new_sha1, new_sha1);
 +      memcpy(cmd->ref_name, refname, reflen);
 +      cmd->ref_name[reflen] = '\0';
 +      *tail = cmd;
 +      return &cmd->next;
 +}
 +
 +static void queue_commands_from_cert(struct command **tail,
 +                                   struct strbuf *push_cert)
 +{
 +      const char *boc, *eoc;
 +
 +      if (*tail)
 +              die("protocol error: got both push certificate and unsigned commands");
 +
 +      boc = strstr(push_cert->buf, "\n\n");
 +      if (!boc)
 +              die("malformed push certificate %.*s", 100, push_cert->buf);
 +      else
 +              boc += 2;
 +      eoc = push_cert->buf + parse_signature(push_cert->buf, push_cert->len);
  
 -      if (shallow_update && !checked_connectivity)
 -              error("BUG: run 'git fsck' for safety.\n"
 -                    "If there are errors, try to remove "
 -                    "the reported refs above");
 +      while (boc < eoc) {
 +              const char *eol = memchr(boc, '\n', eoc - boc);
 +              tail = queue_command(tail, boc, eol ? eol - boc : eoc - eol);
 +              boc = eol ? eol + 1 : eoc;
 +      }
  }
  
  static struct command *read_head_info(struct sha1_array *shallow)
        struct command **p = &commands;
        for (;;) {
                char *line;
 -              unsigned char old_sha1[20], new_sha1[20];
 -              struct command *cmd;
 -              char *refname;
 -              int len, reflen;
 +              int len, linelen;
  
                line = packet_read_line(0, &len);
                if (!line)
                        break;
  
                if (len == 48 && starts_with(line, "shallow ")) {
 -                      if (get_sha1_hex(line + 8, old_sha1))
 -                              die("protocol error: expected shallow sha, got '%s'", line + 8);
 -                      sha1_array_append(shallow, old_sha1);
 +                      unsigned char sha1[20];
 +                      if (get_sha1_hex(line + 8, sha1))
 +                              die("protocol error: expected shallow sha, got '%s'",
 +                                  line + 8);
 +                      sha1_array_append(shallow, sha1);
                        continue;
                }
  
 -              if (len < 83 ||
 -                  line[40] != ' ' ||
 -                  line[81] != ' ' ||
 -                  get_sha1_hex(line, old_sha1) ||
 -                  get_sha1_hex(line + 41, new_sha1))
 -                      die("protocol error: expected old/new/ref, got '%s'",
 -                          line);
 -
 -              refname = line + 82;
 -              reflen = strlen(refname);
 -              if (reflen + 82 < len) {
 -                      const char *feature_list = refname + reflen + 1;
 +              linelen = strlen(line);
 +              if (linelen < len) {
 +                      const char *feature_list = line + linelen + 1;
                        if (parse_feature_request(feature_list, "report-status"))
                                report_status = 1;
                        if (parse_feature_request(feature_list, "side-band-64k"))
                                use_sideband = LARGE_PACKET_MAX;
                        if (parse_feature_request(feature_list, "quiet"))
                                quiet = 1;
 +                      if (advertise_atomic_push
 +                          && parse_feature_request(feature_list, "atomic"))
 +                              use_atomic = 1;
                }
 -              cmd = xcalloc(1, sizeof(struct command) + len - 80);
 -              hashcpy(cmd->old_sha1, old_sha1);
 -              hashcpy(cmd->new_sha1, new_sha1);
 -              memcpy(cmd->ref_name, line + 82, len - 81);
 -              *p = cmd;
 -              p = &cmd->next;
 +
 +              if (!strcmp(line, "push-cert")) {
 +                      int true_flush = 0;
 +                      char certbuf[1024];
 +
 +                      for (;;) {
 +                              len = packet_read(0, NULL, NULL,
 +                                                certbuf, sizeof(certbuf), 0);
 +                              if (!len) {
 +                                      true_flush = 1;
 +                                      break;
 +                              }
 +                              if (!strcmp(certbuf, "push-cert-end\n"))
 +                                      break; /* end of cert */
 +                              strbuf_addstr(&push_cert, certbuf);
 +                      }
 +
 +                      if (true_flush)
 +                              break;
 +                      continue;
 +              }
 +
 +              p = queue_command(p, line, linelen);
        }
 +
 +      if (push_cert.len)
 +              queue_commands_from_cert(p, &push_cert);
 +
        return commands;
  }
  
@@@ -1459,10 -910,11 +1459,10 @@@ static const char *pack_lockfile
  static const char *unpack(int err_fd, struct shallow_info *si)
  {
        struct pack_header hdr;
 -      struct argv_array av = ARGV_ARRAY_INIT;
        const char *hdr_err;
        int status;
        char hdr_arg[38];
 -      struct child_process child;
 +      struct child_process child = CHILD_PROCESS_INIT;
        int fsck_objects = (receive_fsck_objects >= 0
                            ? receive_fsck_objects
                            : transfer_fsck_objects >= 0
  
        if (si->nr_ours || si->nr_theirs) {
                alt_shallow_file = setup_temporary_shallow(si->shallow);
 -              argv_array_pushl(&av, "--shallow-file", alt_shallow_file, NULL);
 +              argv_array_push(&child.args, "--shallow-file");
 +              argv_array_push(&child.args, alt_shallow_file);
        }
  
 -      memset(&child, 0, sizeof(child));
        if (ntohl(hdr.hdr_entries) < unpack_limit) {
 -              argv_array_pushl(&av, "unpack-objects", hdr_arg, NULL);
 +              argv_array_pushl(&child.args, "unpack-objects", hdr_arg, NULL);
                if (quiet)
 -                      argv_array_push(&av, "-q");
 +                      argv_array_push(&child.args, "-q");
                if (fsck_objects)
 -                      argv_array_push(&av, "--strict");
 -              child.argv = av.argv;
 +                      argv_array_push(&child.args, "--strict");
                child.no_stdout = 1;
                child.err = err_fd;
                child.git_cmd = 1;
                if (gethostname(keep_arg + s, sizeof(keep_arg) - s))
                        strcpy(keep_arg + s, "localhost");
  
 -              argv_array_pushl(&av, "index-pack",
 +              argv_array_pushl(&child.args, "index-pack",
                                 "--stdin", hdr_arg, keep_arg, NULL);
                if (fsck_objects)
 -                      argv_array_push(&av, "--strict");
 +                      argv_array_push(&child.args, "--strict");
                if (fix_thin)
 -                      argv_array_push(&av, "--fix-thin");
 -              child.argv = av.argv;
 +                      argv_array_push(&child.args, "--fix-thin");
                child.out = -1;
                child.err = err_fd;
                child.git_cmd = 1;
@@@ -1669,7 -1123,9 +1669,7 @@@ static int delete_only(struct command *
  int cmd_receive_pack(int argc, const char **argv, const char *prefix)
  {
        int advertise_refs = 0;
 -      int stateless_rpc = 0;
        int i;
 -      char *dir = NULL;
        struct command *commands;
        struct sha1_array shallow = SHA1_ARRAY_INIT;
        struct sha1_array ref = SHA1_ARRAY_INIT;
  
                        usage(receive_pack_usage);
                }
 -              if (dir)
 +              if (service_dir)
                        usage(receive_pack_usage);
 -              dir = xstrdup(arg);
 +              service_dir = arg;
        }
 -      if (!dir)
 +      if (!service_dir)
                usage(receive_pack_usage);
  
        setup_path();
  
 -      if (!enter_repo(dir, 0))
 -              die("'%s' does not appear to be a git repository", dir);
 +      if (!enter_repo(service_dir, 0))
 +              die("'%s' does not appear to be a git repository", service_dir);
  
        git_config(receive_pack_config, NULL);
 +      if (cert_nonce_seed)
 +              push_cert_nonce = prepare_push_cert_nonce(service_dir, time(NULL));
  
        if (0 <= transfer_unpack_limit)
                unpack_limit = transfer_unpack_limit;
                packet_flush(1);
        sha1_array_clear(&shallow);
        sha1_array_clear(&ref);
 +      free((void *)push_cert_nonce);
        return 0;
  }