Merge branch 'jc/clone-borrow'

Allow "git clone --reference" to be used more safely.

* jc/clone-borrow:
clone: --dissociate option to mark that reference is only temporary

diff --combined builtin/clone.c
index d5e7532105aa66c5b7e04e170489cf905928b5bb,e1ad4df41f5a1044b3ce7ec1ce82df0bb22fc903..316c75d0b342d039696608c18adfabaa3366b0e7
--- 1/builtin/clone.c
--- 2/builtin/clone.c
+++ b/builtin/clone.c
@@@ -9,7 -9,6 +9,7 @@@
   */
  
  #include "builtin.h"
 +#include "lockfile.h"
  #include "parse-options.h"
  #include "fetch-pack.h"
  #include "refs.h"
@@@ -49,6 -48,7 +49,7 @@@ static int option_verbosity
  static int option_progress = -1;
  static struct string_list option_config;
  static struct string_list option_reference;
+ static int option_dissociate;
  
  static int opt_parse_reference(const struct option *opt, const char *arg, int unset)
  {
@@@ -94,6 -94,8 +95,8 @@@ static struct option builtin_clone_opti
                    N_("create a shallow clone of that depth")),
        OPT_BOOL(0, "single-branch", &option_single_branch,
                    N_("clone only one branch, HEAD or --branch")),
+       OPT_BOOL(0, "dissociate", &option_dissociate,
+                N_("use --reference only while cloning")),
        OPT_STRING(0, "separate-git-dir", &real_git_dir, N_("gitdir"),
                   N_("separate git dir from working tree")),
        OPT_STRING_LIST('c', "config", &option_config, N_("key=value"),
@@@ -391,6 -393,7 +394,6 @@@ static void clone_local(const char *src
  
  static const char *junk_work_tree;
  static const char *junk_git_dir;
 -static pid_t junk_pid;
  static enum {
        JUNK_LEAVE_NONE,
        JUNK_LEAVE_REPO,
@@@ -417,6 -420,8 +420,6 @@@ static void remove_junk(void
                break;
        }
  
 -      if (getpid() != junk_pid)
 -              return;
        if (junk_git_dir) {
                strbuf_addstr(&sb, junk_git_dir);
                remove_dir_recursively(&sb, 0);
@@@ -620,7 -625,7 +623,7 @@@ static int checkout(void
        if (option_no_checkout)
                return 0;
  
 -      head = resolve_refdup("HEAD", sha1, 1, NULL);
 +      head = resolve_refdup("HEAD", RESOLVE_REF_READING, sha1, NULL);
        if (!head) {
                warning(_("remote HEAD refers to nonexistent ref, "
                          "unable to checkout.\n"));
@@@ -683,10 -688,9 +686,10 @@@ static void write_config(struct string_
        }
  }
  
 -static void write_refspec_config(const char* src_ref_prefix,
 -              const struct ref* our_head_points_at,
 -              const struct ref* remote_head_points_at, struct strbuf* branch_top)
 +static void write_refspec_config(const char *src_ref_prefix,
 +              const struct ref *our_head_points_at,
 +              const struct ref *remote_head_points_at,
 +              struct strbuf *branch_top)
  {
        struct strbuf key = STRBUF_INIT;
        struct strbuf value = STRBUF_INIT;
@@@ -735,6 -739,16 +738,16 @@@
        strbuf_release(&value);
  }
  
+ static void dissociate_from_references(void)
+ {
+       static const char* argv[] = { "repack", "-a", "-d", NULL };
+ 
+       if (run_command_v_opt(argv, RUN_GIT_CMD|RUN_COMMAND_NO_STDIN))
+               die(_("cannot repack to clean up"));
+       if (unlink(git_path("objects/info/alternates")) && errno != ENOENT)
+               die_errno(_("cannot unlink temporary alternates file"));
+ }
+ 
  int cmd_clone(int argc, const char **argv, const char *prefix)
  {
        int is_bundle = 0, is_local;
@@@ -757,6 -771,8 +770,6 @@@
        struct refspec *refspec;
        const char *fetch_pattern;
  
 -      junk_pid = getpid();
 -
        packet_trace_identity("clone");
        argc = parse_options(argc, argv, prefix, builtin_clone_options,
                             builtin_clone_usage, 0);
@@@ -880,6 -896,10 +893,10 @@@
  
        if (option_reference.nr)
                setup_reference();
+       else if (option_dissociate) {
+               warning(_("--dissociate given, but there is no --reference"));
+               option_dissociate = 0;
+       }
  
        fetch_pattern = value.buf;
        refspec = parse_fetch_refspec(1, &fetch_pattern);
@@@ -993,6 -1013,9 +1010,9 @@@
        transport_unlock_pack(transport);
        transport_disconnect(transport);
  
+       if (option_dissociate)
+               dissociate_from_references();
+ 
        junk_mode = JUNK_LEAVE_REPO;
        err = checkout();
  
@@@ -1001,7 -1024,5 +1021,7 @@@
        strbuf_release(&key);
        strbuf_release(&value);
        junk_mode = JUNK_LEAVE_ALL;
 +
 +      free(refspec);
        return err;
  }