Merge branch 'cc/reset-keep'

* cc/reset-keep:
  Documentation: improve description of "git reset --keep"
  reset: disallow using --keep when there are unmerged entries
  reset: disallow "reset --keep" outside a work tree
  Documentation: reset: describe new "--keep" option
  reset: add test cases for "--keep" option
  reset: add option "--keep" to "git reset"

diff --cc builtin/reset.c
index 0f5022eed24f980f6fedee49f8602fefa6fe85e4,0000000000000000000000000000000000000000..2c3a69adc674bb3f539d29b2d29116e89f887066
mode 100644,000000..100644
--- 1/builtin/reset.c
--- /dev/null
+++ b/builtin/reset.c
@@@ -1,356 -1,0 +1,385 @@@
-       "git reset [--mixed | --soft | --hard | --merge] [-q] [<commit>]",
 +/*
 + * "git reset" builtin command
 + *
 + * Copyright (c) 2007 Carlos Rica
 + *
 + * Based on git-reset.sh, which is
 + *
 + * Copyright (c) 2005, 2006 Linus Torvalds and Junio C Hamano
 + */
 +#include "cache.h"
 +#include "tag.h"
 +#include "object.h"
 +#include "commit.h"
 +#include "run-command.h"
 +#include "refs.h"
 +#include "diff.h"
 +#include "diffcore.h"
 +#include "tree.h"
 +#include "branch.h"
 +#include "parse-options.h"
 +#include "unpack-trees.h"
 +#include "cache-tree.h"
 +
 +static const char * const git_reset_usage[] = {
- enum reset_type { MIXED, SOFT, HARD, MERGE, NONE };
- static const char *reset_type_names[] = { "mixed", "soft", "hard", "merge", NULL };
++      "git reset [--mixed | --soft | --hard | --merge | --keep] [-q] [<commit>]",
 +      "git reset [--mixed] <commit> [--] <paths>...",
 +      NULL
 +};
 +
-       if (reset_type == HARD || reset_type == MERGE)
++enum reset_type { MIXED, SOFT, HARD, MERGE, KEEP, NONE };
++static const char *reset_type_names[] = {
++      "mixed", "soft", "hard", "merge", "keep", NULL
++};
 +
 +static char *args_to_str(const char **argv)
 +{
 +      char *buf = NULL;
 +      unsigned long len, space = 0, nr = 0;
 +
 +      for (; *argv; argv++) {
 +              len = strlen(*argv);
 +              ALLOC_GROW(buf, nr + 1 + len, space);
 +              if (nr)
 +                      buf[nr++] = ' ';
 +              memcpy(buf + nr, *argv, len);
 +              nr += len;
 +      }
 +      ALLOC_GROW(buf, nr + 1, space);
 +      buf[nr] = '\0';
 +
 +      return buf;
 +}
 +
 +static inline int is_merge(void)
 +{
 +      return !access(git_path("MERGE_HEAD"), F_OK);
 +}
 +
 +static int reset_index_file(const unsigned char *sha1, int reset_type, int quiet)
 +{
 +      int nr = 1;
 +      int newfd;
 +      struct tree_desc desc[2];
 +      struct unpack_trees_options opts;
 +      struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 +
 +      memset(&opts, 0, sizeof(opts));
 +      opts.head_idx = 1;
 +      opts.src_index = &the_index;
 +      opts.dst_index = &the_index;
 +      opts.fn = oneway_merge;
 +      opts.merge = 1;
 +      if (!quiet)
 +              opts.verbose_update = 1;
 +      switch (reset_type) {
++      case KEEP:
 +      case MERGE:
 +              opts.update = 1;
 +              break;
 +      case HARD:
 +              opts.update = 1;
 +              /* fallthrough */
 +      default:
 +              opts.reset = 1;
 +      }
 +
 +      newfd = hold_locked_index(lock, 1);
 +
 +      read_cache_unmerged();
 +
++      if (reset_type == KEEP) {
++              unsigned char head_sha1[20];
++              if (get_sha1("HEAD", head_sha1))
++                      return error("You do not have a valid HEAD.");
++              if (!fill_tree_descriptor(desc, head_sha1))
++                      return error("Failed to find tree of HEAD.");
++              nr++;
++              opts.fn = twoway_merge;
++      }
++
 +      if (!fill_tree_descriptor(desc + nr - 1, sha1))
 +              return error("Failed to find tree of %s.", sha1_to_hex(sha1));
 +      if (unpack_trees(nr, desc, &opts))
 +              return -1;
 +      if (write_cache(newfd, active_cache, active_nr) ||
 +          commit_locked_index(lock))
 +              return error("Could not write new index file.");
 +
 +      return 0;
 +}
 +
 +static void print_new_head_line(struct commit *commit)
 +{
 +      const char *hex, *body;
 +
 +      hex = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
 +      printf("HEAD is now at %s", hex);
 +      body = strstr(commit->buffer, "\n\n");
 +      if (body) {
 +              const char *eol;
 +              size_t len;
 +              body += 2;
 +              eol = strchr(body, '\n');
 +              len = eol ? eol - body : strlen(body);
 +              printf(" %.*s\n", (int) len, body);
 +      }
 +      else
 +              printf("\n");
 +}
 +
 +static int update_index_refresh(int fd, struct lock_file *index_lock, int flags)
 +{
 +      int result;
 +
 +      if (!index_lock) {
 +              index_lock = xcalloc(1, sizeof(struct lock_file));
 +              fd = hold_locked_index(index_lock, 1);
 +      }
 +
 +      if (read_cache() < 0)
 +              return error("Could not read index");
 +
 +      result = refresh_index(&the_index, (flags), NULL, NULL,
 +                             "Unstaged changes after reset:") ? 1 : 0;
 +      if (write_cache(fd, active_cache, active_nr) ||
 +                      commit_locked_index(index_lock))
 +              return error ("Could not refresh index");
 +      return result;
 +}
 +
 +static void update_index_from_diff(struct diff_queue_struct *q,
 +              struct diff_options *opt, void *data)
 +{
 +      int i;
 +      int *discard_flag = data;
 +
 +      /* do_diff_cache() mangled the index */
 +      discard_cache();
 +      *discard_flag = 1;
 +      read_cache();
 +
 +      for (i = 0; i < q->nr; i++) {
 +              struct diff_filespec *one = q->queue[i]->one;
 +              if (one->mode) {
 +                      struct cache_entry *ce;
 +                      ce = make_cache_entry(one->mode, one->sha1, one->path,
 +                              0, 0);
 +                      if (!ce)
 +                              die("make_cache_entry failed for path '%s'",
 +                                  one->path);
 +                      add_cache_entry(ce, ADD_CACHE_OK_TO_ADD |
 +                              ADD_CACHE_OK_TO_REPLACE);
 +              } else
 +                      remove_file_from_cache(one->path);
 +      }
 +}
 +
 +static int interactive_reset(const char *revision, const char **argv,
 +                           const char *prefix)
 +{
 +      const char **pathspec = NULL;
 +
 +      if (*argv)
 +              pathspec = get_pathspec(prefix, argv);
 +
 +      return run_add_interactive(revision, "--patch=reset", pathspec);
 +}
 +
 +static int read_from_tree(const char *prefix, const char **argv,
 +              unsigned char *tree_sha1, int refresh_flags)
 +{
 +      struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 +      int index_fd, index_was_discarded = 0;
 +      struct diff_options opt;
 +
 +      memset(&opt, 0, sizeof(opt));
 +      diff_tree_setup_paths(get_pathspec(prefix, (const char **)argv), &opt);
 +      opt.output_format = DIFF_FORMAT_CALLBACK;
 +      opt.format_callback = update_index_from_diff;
 +      opt.format_callback_data = &index_was_discarded;
 +
 +      index_fd = hold_locked_index(lock, 1);
 +      index_was_discarded = 0;
 +      read_cache();
 +      if (do_diff_cache(tree_sha1, &opt))
 +              return 1;
 +      diffcore_std(&opt);
 +      diff_flush(&opt);
 +      diff_tree_release_paths(&opt);
 +
 +      if (!index_was_discarded)
 +              /* The index is still clobbered from do_diff_cache() */
 +              discard_cache();
 +      return update_index_refresh(index_fd, lock, refresh_flags);
 +}
 +
 +static void prepend_reflog_action(const char *action, char *buf, size_t size)
 +{
 +      const char *sep = ": ";
 +      const char *rla = getenv("GIT_REFLOG_ACTION");
 +      if (!rla)
 +              rla = sep = "";
 +      if (snprintf(buf, size, "%s%s%s", rla, sep, action) >= size)
 +              warning("Reflog action message too long: %.*s...", 50, buf);
 +}
 +
++static void die_if_unmerged_cache(int reset_type)
++{
++      if (is_merge() || read_cache() < 0 || unmerged_cache())
++              die("Cannot do a %s reset in the middle of a merge.",
++                  reset_type_names[reset_type]);
++
++}
++
 +int cmd_reset(int argc, const char **argv, const char *prefix)
 +{
 +      int i = 0, reset_type = NONE, update_ref_status = 0, quiet = 0;
 +      int patch_mode = 0;
 +      const char *rev = "HEAD";
 +      unsigned char sha1[20], *orig = NULL, sha1_orig[20],
 +                              *old_orig = NULL, sha1_old_orig[20];
 +      struct commit *commit;
 +      char *reflog_action, msg[1024];
 +      const struct option options[] = {
 +              OPT__QUIET(&quiet),
 +              OPT_SET_INT(0, "mixed", &reset_type,
 +                                              "reset HEAD and index", MIXED),
 +              OPT_SET_INT(0, "soft", &reset_type, "reset only HEAD", SOFT),
 +              OPT_SET_INT(0, "hard", &reset_type,
 +                              "reset HEAD, index and working tree", HARD),
 +              OPT_SET_INT(0, "merge", &reset_type,
 +                              "reset HEAD, index and working tree", MERGE),
++              OPT_SET_INT(0, "keep", &reset_type,
++                              "reset HEAD but keep local changes", KEEP),
 +              OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
 +              OPT_END()
 +      };
 +
 +      git_config(git_default_config, NULL);
 +
 +      argc = parse_options(argc, argv, prefix, options, git_reset_usage,
 +                                              PARSE_OPT_KEEP_DASHDASH);
 +      reflog_action = args_to_str(argv);
 +      setenv("GIT_REFLOG_ACTION", reflog_action, 0);
 +
 +      /*
 +       * Possible arguments are:
 +       *
 +       * git reset [-opts] <rev> <paths>...
 +       * git reset [-opts] <rev> -- <paths>...
 +       * git reset [-opts] -- <paths>...
 +       * git reset [-opts] <paths>...
 +       *
 +       * At this point, argv[i] points immediately after [-opts].
 +       */
 +
 +      if (i < argc) {
 +              if (!strcmp(argv[i], "--")) {
 +                      i++; /* reset to HEAD, possibly with paths */
 +              } else if (i + 1 < argc && !strcmp(argv[i+1], "--")) {
 +                      rev = argv[i];
 +                      i += 2;
 +              }
 +              /*
 +               * Otherwise, argv[i] could be either <rev> or <paths> and
 +               * has to be unambiguous.
 +               */
 +              else if (!get_sha1(argv[i], sha1)) {
 +                      /*
 +                       * Ok, argv[i] looks like a rev; it should not
 +                       * be a filename.
 +                       */
 +                      verify_non_filename(prefix, argv[i]);
 +                      rev = argv[i++];
 +              } else {
 +                      /* Otherwise we treat this as a filename */
 +                      verify_filename(prefix, argv[i]);
 +              }
 +      }
 +
 +      if (get_sha1(rev, sha1))
 +              die("Failed to resolve '%s' as a valid ref.", rev);
 +
 +      commit = lookup_commit_reference(sha1);
 +      if (!commit)
 +              die("Could not parse object '%s'.", rev);
 +      hashcpy(sha1, commit->object.sha1);
 +
 +      if (patch_mode) {
 +              if (reset_type != NONE)
 +                      die("--patch is incompatible with --{hard,mixed,soft}");
 +              return interactive_reset(rev, argv + i, prefix);
 +      }
 +
 +      /* git reset tree [--] paths... can be used to
 +       * load chosen paths from the tree into the index without
 +       * affecting the working tree nor HEAD. */
 +      if (i < argc) {
 +              if (reset_type == MIXED)
 +                      warning("--mixed option is deprecated with paths.");
 +              else if (reset_type != NONE)
 +                      die("Cannot do %s reset with paths.",
 +                                      reset_type_names[reset_type]);
 +              return read_from_tree(prefix, argv + i, sha1,
 +                              quiet ? REFRESH_QUIET : REFRESH_IN_PORCELAIN);
 +      }
 +      if (reset_type == NONE)
 +              reset_type = MIXED; /* by default */
 +
-       if (reset_type == SOFT) {
-               if (is_merge() || read_cache() < 0 || unmerged_cache())
-                       die("Cannot do a soft reset in the middle of a merge.");
++      if (reset_type != SOFT && reset_type != MIXED)
 +              setup_work_tree();
 +
 +      if (reset_type == MIXED && is_bare_repository())
 +              die("%s reset is not allowed in a bare repository",
 +                  reset_type_names[reset_type]);
 +
 +      /* Soft reset does not touch the index file nor the working tree
 +       * at all, but requires them in a good order.  Other resets reset
 +       * the index file to the tree object we are switching to. */
-       else if (reset_index_file(sha1, reset_type, quiet))
-               die("Could not reset index file to revision '%s'.", rev);
++      if (reset_type == SOFT)
++              die_if_unmerged_cache(reset_type);
++      else {
++              int err;
++              if (reset_type == KEEP)
++                      die_if_unmerged_cache(reset_type);
++              err = reset_index_file(sha1, reset_type, quiet);
++              if (reset_type == KEEP)
++                      err = err || reset_index_file(sha1, MIXED, quiet);
++              if (err)
++                      die("Could not reset index file to revision '%s'.", rev);
 +      }
 +
 +      /* Any resets update HEAD to the head being switched to,
 +       * saving the previous head in ORIG_HEAD before. */
 +      if (!get_sha1("ORIG_HEAD", sha1_old_orig))
 +              old_orig = sha1_old_orig;
 +      if (!get_sha1("HEAD", sha1_orig)) {
 +              orig = sha1_orig;
 +              prepend_reflog_action("updating ORIG_HEAD", msg, sizeof(msg));
 +              update_ref(msg, "ORIG_HEAD", orig, old_orig, 0, MSG_ON_ERR);
 +      }
 +      else if (old_orig)
 +              delete_ref("ORIG_HEAD", old_orig, 0);
 +      prepend_reflog_action("updating HEAD", msg, sizeof(msg));
 +      update_ref_status = update_ref(msg, "HEAD", sha1, orig, 0, MSG_ON_ERR);
 +
 +      switch (reset_type) {
 +      case HARD:
 +              if (!update_ref_status && !quiet)
 +                      print_new_head_line(commit);
 +              break;
 +      case SOFT: /* Nothing else to do. */
 +              break;
 +      case MIXED: /* Report what has not been updated. */
 +              update_index_refresh(0, NULL,
 +                              quiet ? REFRESH_QUIET : REFRESH_IN_PORCELAIN);
 +              break;
 +      }
 +
 +      remove_branch_state();
 +
 +      free(reflog_action);
 +
 +      return update_ref_status;
 +}