builtin-reset.c

   1 /*
   2  * "git reset" builtin command
   3  *
   4  * Copyright (c) 2007 Carlos Rica
   5  *
   6  * Based on git-reset.sh, which is
   7  *
   8  * Copyright (c) 2005, 2006 Linus Torvalds and Junio C Hamano
   9  */
  10 #include "cache.h"
  11 #include "tag.h"
  12 #include "object.h"
  13 #include "commit.h"
  14 #include "run-command.h"
  15 #include "refs.h"
  16 #include "diff.h"
  17 #include "diffcore.h"
  18 #include "tree.h"
  19 #include "branch.h"
  20 #include "parse-options.h"
  21
  22 static const char * const git_reset_usage[] = {
  23         "git-reset [--mixed | --soft | --hard] [-q] [<commit>]",
  24         "git-reset [--mixed] <commit> [--] <paths>...",
  25         NULL
  26 };
  27
  28 static char *args_to_str(const char **argv)
  29 {
  30         char *buf = NULL;
  31         unsigned long len, space = 0, nr = 0;
  32
  33         for (; *argv; argv++) {
  34                 len = strlen(*argv);
  35                 ALLOC_GROW(buf, nr + 1 + len, space);
  36                 if (nr)
  37                         buf[nr++] = ' ';
  38                 memcpy(buf + nr, *argv, len);
  39                 nr += len;
  40         }
  41         ALLOC_GROW(buf, nr + 1, space);
  42         buf[nr] = '\0';
  43
  44         return buf;
  45 }
  46
  47 static inline int is_merge(void)
  48 {
  49         return !access(git_path("MERGE_HEAD"), F_OK);
  50 }
  51
  52 static int reset_index_file(const unsigned char *sha1, int is_hard_reset)
  53 {
  54         int i = 0;
  55         const char *args[6];
  56
  57         args[i++] = "read-tree";
  58         args[i++] = "-v";
  59         args[i++] = "--reset";
  60         if (is_hard_reset)
  61                 args[i++] = "-u";
  62         args[i++] = sha1_to_hex(sha1);
  63         args[i] = NULL;
  64
  65         return run_command_v_opt(args, RUN_GIT_CMD);
  66 }
  67
  68 static void print_new_head_line(struct commit *commit)
  69 {
  70         const char *hex, *body;
  71
  72         hex = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
  73         printf("HEAD is now at %s", hex);
  74         body = strstr(commit->buffer, "\n\n");
  75         if (body) {
  76                 const char *eol;
  77                 size_t len;
  78                 body += 2;
  79                 eol = strchr(body, '\n');
  80                 len = eol ? eol - body : strlen(body);
  81                 printf(" %.*s\n", (int) len, body);
  82         }
  83         else
  84                 printf("\n");
  85 }
  86
  87 static int update_index_refresh(int fd, struct lock_file *index_lock)
  88 {
  89         int result;
  90
  91         if (!index_lock) {
  92                 index_lock = xcalloc(1, sizeof(struct lock_file));
  93                 fd = hold_locked_index(index_lock, 1);
  94         }
  95
  96         if (read_cache() < 0)
  97                 return error("Could not read index");
  98         result = refresh_cache(0) ? 1 : 0;
  99         if (write_cache(fd, active_cache, active_nr) ||
 100                         commit_locked_index(index_lock))
 101                 return error ("Could not refresh index");
 102         return result;
 103 }
 104
 105 static void update_index_from_diff(struct diff_queue_struct *q,
 106                 struct diff_options *opt, void *data)
 107 {
 108         int i;
 109         int *discard_flag = data;
 110
 111         /* do_diff_cache() mangled the index */
 112         discard_cache();
 113         *discard_flag = 1;
 114         read_cache();
 115
 116         for (i = 0; i < q->nr; i++) {
 117                 struct diff_filespec *one = q->queue[i]->one;
 118                 if (one->mode) {
 119                         struct cache_entry *ce;
 120                         ce = make_cache_entry(one->mode, one->sha1, one->path,
 121                                 0, 0);
 122                         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD |
 123                                 ADD_CACHE_OK_TO_REPLACE);
 124                 } else
 125                         remove_file_from_cache(one->path);
 126         }
 127 }
 128
 129 static int read_from_tree(const char *prefix, const char **argv,
 130                 unsigned char *tree_sha1)
 131 {
 132         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 133         int index_fd, index_was_discarded = 0;
 134         struct diff_options opt;
 135
 136         memset(&opt, 0, sizeof(opt));
 137         diff_tree_setup_paths(get_pathspec(prefix, (const char **)argv), &opt);
 138         opt.output_format = DIFF_FORMAT_CALLBACK;
 139         opt.format_callback = update_index_from_diff;
 140         opt.format_callback_data = &index_was_discarded;
 141
 142         index_fd = hold_locked_index(lock, 1);
 143         index_was_discarded = 0;
 144         read_cache();
 145         if (do_diff_cache(tree_sha1, &opt))
 146                 return 1;
 147         diffcore_std(&opt);
 148         diff_flush(&opt);
 149         diff_tree_release_paths(&opt);
 150
 151         if (!index_was_discarded)
 152                 /* The index is still clobbered from do_diff_cache() */
 153                 discard_cache();
 154         return update_index_refresh(index_fd, lock);
 155 }
 156
 157 static void prepend_reflog_action(const char *action, char *buf, size_t size)
 158 {
 159         const char *sep = ": ";
 160         const char *rla = getenv("GIT_REFLOG_ACTION");
 161         if (!rla)
 162                 rla = sep = "";
 163         if (snprintf(buf, size, "%s%s%s", rla, sep, action) >= size)
 164                 warning("Reflog action message too long: %.*s...", 50, buf);
 165 }
 166
 167 enum reset_type { MIXED, SOFT, HARD, NONE };
 168 static const char *reset_type_names[] = { "mixed", "soft", "hard", NULL };
 169
 170 int cmd_reset(int argc, const char **argv, const char *prefix)
 171 {
 172         int i = 0, reset_type = NONE, update_ref_status = 0, quiet = 0;
 173         const char *rev = "HEAD";
 174         unsigned char sha1[20], *orig = NULL, sha1_orig[20],
 175                                 *old_orig = NULL, sha1_old_orig[20];
 176         struct commit *commit;
 177         char *reflog_action, msg[1024];
 178         const struct option options[] = {
 179                 OPT_SET_INT(0, "mixed", &reset_type,
 180                                                 "reset HEAD and index", MIXED),
 181                 OPT_SET_INT(0, "soft", &reset_type, "reset only HEAD", SOFT),
 182                 OPT_SET_INT(0, "hard", &reset_type,
 183                                 "reset HEAD, index and working tree", HARD),
 184                 OPT_BOOLEAN('q', NULL, &quiet,
 185                                 "disable showing new HEAD in hard reset"),
 186                 OPT_END()
 187         };
 188
 189         git_config(git_default_config);
 190
 191         argc = parse_options(argc, argv, options, git_reset_usage,
 192                                                 PARSE_OPT_KEEP_DASHDASH);
 193         reflog_action = args_to_str(argv);
 194         setenv("GIT_REFLOG_ACTION", reflog_action, 0);
 195
 196         if (i < argc && strcmp(argv[i], "--"))
 197                 rev = argv[i++];
 198
 199         if (get_sha1(rev, sha1))
 200                 die("Failed to resolve '%s' as a valid ref.", rev);
 201
 202         commit = lookup_commit_reference(sha1);
 203         if (!commit)
 204                 die("Could not parse object '%s'.", rev);
 205         hashcpy(sha1, commit->object.sha1);
 206
 207         if (i < argc && !strcmp(argv[i], "--"))
 208                 i++;
 209
 210         /* git reset tree [--] paths... can be used to
 211          * load chosen paths from the tree into the index without
 212          * affecting the working tree nor HEAD. */
 213         if (i < argc) {
 214                 if (reset_type == MIXED)
 215                         warning("--mixed option is deprecated with paths.");
 216                 else if (reset_type != NONE)
 217                         die("Cannot do %s reset with paths.",
 218                                         reset_type_names[reset_type]);
 219                 return read_from_tree(prefix, argv + i, sha1);
 220         }
 221         if (reset_type == NONE)
 222                 reset_type = MIXED; /* by default */
 223
 224         if (reset_type == HARD && is_bare_repository())
 225                 die("hard reset makes no sense in a bare repository");
 226
 227         /* Soft reset does not touch the index file nor the working tree
 228          * at all, but requires them in a good order.  Other resets reset
 229          * the index file to the tree object we are switching to. */
 230         if (reset_type == SOFT) {
 231                 if (is_merge() || read_cache() < 0 || unmerged_cache())
 232                         die("Cannot do a soft reset in the middle of a merge.");
 233         }
 234         else if (reset_index_file(sha1, (reset_type == HARD)))
 235                 die("Could not reset index file to revision '%s'.", rev);
 236
 237         /* Any resets update HEAD to the head being switched to,
 238          * saving the previous head in ORIG_HEAD before. */
 239         if (!get_sha1("ORIG_HEAD", sha1_old_orig))
 240                 old_orig = sha1_old_orig;
 241         if (!get_sha1("HEAD", sha1_orig)) {
 242                 orig = sha1_orig;
 243                 prepend_reflog_action("updating ORIG_HEAD", msg, sizeof(msg));
 244                 update_ref(msg, "ORIG_HEAD", orig, old_orig, 0, MSG_ON_ERR);
 245         }
 246         else if (old_orig)
 247                 delete_ref("ORIG_HEAD", old_orig);
 248         prepend_reflog_action("updating HEAD", msg, sizeof(msg));
 249         update_ref_status = update_ref(msg, "HEAD", sha1, orig, 0, MSG_ON_ERR);
 250
 251         switch (reset_type) {
 252         case HARD:
 253                 if (!update_ref_status && !quiet)
 254                         print_new_head_line(commit);
 255                 break;
 256         case SOFT: /* Nothing else to do. */
 257                 break;
 258         case MIXED: /* Report what has not been updated. */
 259                 update_index_refresh(0, NULL);
 260                 break;
 261         }
 262
 263         remove_branch_state();
 264
 265         free(reflog_action);
 266
 267         return update_ref_status;
 268 }