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![Jeff King](/assets/img/avatar_default.png)
We sometimes sprintf into fixed-size buffers when we know that the buffer is large enough to fit the input (either because it's a constant, or because it's numeric input that is bounded in size). Likewise with strcpy of constant strings. However, these sites make it hard to audit sprintf and strcpy calls for buffer overflows, as a reader has to cross-reference the size of the array with the input. Let's use xsnprintf instead, which communicates to a reader that we don't expect this to overflow (and catches the mistake in case we do). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
250 lines
7 KiB
C
250 lines
7 KiB
C
/*
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* GIT - The information manager from hell
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*
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* Copyright (C) Linus Torvalds, 2005
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*/
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#include "cache.h"
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#include "lockfile.h"
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#include "object.h"
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#include "tree.h"
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#include "tree-walk.h"
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#include "cache-tree.h"
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#include "unpack-trees.h"
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#include "dir.h"
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#include "builtin.h"
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#include "parse-options.h"
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#include "resolve-undo.h"
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static int nr_trees;
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static int read_empty;
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static struct tree *trees[MAX_UNPACK_TREES];
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static int list_tree(unsigned char *sha1)
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{
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struct tree *tree;
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if (nr_trees >= MAX_UNPACK_TREES)
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die("I cannot read more than %d trees", MAX_UNPACK_TREES);
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tree = parse_tree_indirect(sha1);
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if (!tree)
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return -1;
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trees[nr_trees++] = tree;
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return 0;
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}
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static const char * const read_tree_usage[] = {
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N_("git read-tree [(-m [--trivial] [--aggressive] | --reset | --prefix=<prefix>) [-u [--exclude-per-directory=<gitignore>] | -i]] [--no-sparse-checkout] [--index-output=<file>] (--empty | <tree-ish1> [<tree-ish2> [<tree-ish3>]])"),
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NULL
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};
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static int index_output_cb(const struct option *opt, const char *arg,
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int unset)
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{
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set_alternate_index_output(arg);
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return 0;
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}
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static int exclude_per_directory_cb(const struct option *opt, const char *arg,
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int unset)
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{
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struct dir_struct *dir;
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struct unpack_trees_options *opts;
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opts = (struct unpack_trees_options *)opt->value;
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if (opts->dir)
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die("more than one --exclude-per-directory given.");
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dir = xcalloc(1, sizeof(*opts->dir));
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dir->flags |= DIR_SHOW_IGNORED;
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dir->exclude_per_dir = arg;
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opts->dir = dir;
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/* We do not need to nor want to do read-directory
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* here; we are merely interested in reusing the
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* per directory ignore stack mechanism.
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*/
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return 0;
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}
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static void debug_stage(const char *label, const struct cache_entry *ce,
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struct unpack_trees_options *o)
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{
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printf("%s ", label);
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if (!ce)
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printf("(missing)\n");
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else if (ce == o->df_conflict_entry)
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printf("(conflict)\n");
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else
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printf("%06o #%d %s %.8s\n",
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ce->ce_mode, ce_stage(ce), ce->name,
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sha1_to_hex(ce->sha1));
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}
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static int debug_merge(const struct cache_entry * const *stages,
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struct unpack_trees_options *o)
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{
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int i;
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printf("* %d-way merge\n", o->merge_size);
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debug_stage("index", stages[0], o);
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for (i = 1; i <= o->merge_size; i++) {
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char buf[24];
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xsnprintf(buf, sizeof(buf), "ent#%d", i);
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debug_stage(buf, stages[i], o);
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}
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return 0;
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}
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static struct lock_file lock_file;
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int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
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{
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int i, stage = 0;
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unsigned char sha1[20];
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struct tree_desc t[MAX_UNPACK_TREES];
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struct unpack_trees_options opts;
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int prefix_set = 0;
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const struct option read_tree_options[] = {
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{ OPTION_CALLBACK, 0, "index-output", NULL, N_("file"),
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N_("write resulting index to <file>"),
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PARSE_OPT_NONEG, index_output_cb },
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OPT_SET_INT(0, "empty", &read_empty,
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N_("only empty the index"), 1),
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OPT__VERBOSE(&opts.verbose_update, N_("be verbose")),
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OPT_GROUP(N_("Merging")),
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OPT_SET_INT('m', NULL, &opts.merge,
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N_("perform a merge in addition to a read"), 1),
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OPT_SET_INT(0, "trivial", &opts.trivial_merges_only,
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N_("3-way merge if no file level merging required"), 1),
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OPT_SET_INT(0, "aggressive", &opts.aggressive,
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N_("3-way merge in presence of adds and removes"), 1),
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OPT_SET_INT(0, "reset", &opts.reset,
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N_("same as -m, but discard unmerged entries"), 1),
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{ OPTION_STRING, 0, "prefix", &opts.prefix, N_("<subdirectory>/"),
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N_("read the tree into the index under <subdirectory>/"),
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PARSE_OPT_NONEG | PARSE_OPT_LITERAL_ARGHELP },
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OPT_SET_INT('u', NULL, &opts.update,
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N_("update working tree with merge result"), 1),
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{ OPTION_CALLBACK, 0, "exclude-per-directory", &opts,
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N_("gitignore"),
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N_("allow explicitly ignored files to be overwritten"),
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PARSE_OPT_NONEG, exclude_per_directory_cb },
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OPT_SET_INT('i', NULL, &opts.index_only,
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N_("don't check the working tree after merging"), 1),
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OPT__DRY_RUN(&opts.dry_run, N_("don't update the index or the work tree")),
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OPT_SET_INT(0, "no-sparse-checkout", &opts.skip_sparse_checkout,
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N_("skip applying sparse checkout filter"), 1),
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OPT_SET_INT(0, "debug-unpack", &opts.debug_unpack,
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N_("debug unpack-trees"), 1),
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OPT_END()
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};
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memset(&opts, 0, sizeof(opts));
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opts.head_idx = -1;
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opts.src_index = &the_index;
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opts.dst_index = &the_index;
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git_config(git_default_config, NULL);
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argc = parse_options(argc, argv, unused_prefix, read_tree_options,
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read_tree_usage, 0);
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hold_locked_index(&lock_file, 1);
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prefix_set = opts.prefix ? 1 : 0;
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if (1 < opts.merge + opts.reset + prefix_set)
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die("Which one? -m, --reset, or --prefix?");
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/*
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* NEEDSWORK
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*
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* The old index should be read anyway even if we're going to
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* destroy all index entries because we still need to preserve
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* certain information such as index version or split-index
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* mode.
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*/
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if (opts.reset || opts.merge || opts.prefix) {
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if (read_cache_unmerged() && (opts.prefix || opts.merge))
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die("You need to resolve your current index first");
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stage = opts.merge = 1;
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}
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resolve_undo_clear();
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for (i = 0; i < argc; i++) {
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const char *arg = argv[i];
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if (get_sha1(arg, sha1))
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die("Not a valid object name %s", arg);
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if (list_tree(sha1) < 0)
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die("failed to unpack tree object %s", arg);
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stage++;
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}
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if (nr_trees == 0 && !read_empty)
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warning("read-tree: emptying the index with no arguments is deprecated; use --empty");
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else if (nr_trees > 0 && read_empty)
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die("passing trees as arguments contradicts --empty");
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if (1 < opts.index_only + opts.update)
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die("-u and -i at the same time makes no sense");
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if ((opts.update || opts.index_only) && !opts.merge)
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die("%s is meaningless without -m, --reset, or --prefix",
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opts.update ? "-u" : "-i");
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if ((opts.dir && !opts.update))
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die("--exclude-per-directory is meaningless unless -u");
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if (opts.merge && !opts.index_only)
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setup_work_tree();
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if (opts.merge) {
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if (stage < 2)
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die("just how do you expect me to merge %d trees?", stage-1);
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switch (stage - 1) {
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case 1:
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opts.fn = opts.prefix ? bind_merge : oneway_merge;
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break;
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case 2:
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opts.fn = twoway_merge;
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opts.initial_checkout = is_cache_unborn();
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break;
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case 3:
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default:
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opts.fn = threeway_merge;
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break;
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}
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if (stage - 1 >= 3)
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opts.head_idx = stage - 2;
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else
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opts.head_idx = 1;
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}
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if (opts.debug_unpack)
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opts.fn = debug_merge;
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cache_tree_free(&active_cache_tree);
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for (i = 0; i < nr_trees; i++) {
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struct tree *tree = trees[i];
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parse_tree(tree);
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init_tree_desc(t+i, tree->buffer, tree->size);
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}
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if (unpack_trees(nr_trees, t, &opts))
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return 128;
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if (opts.debug_unpack || opts.dry_run)
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return 0; /* do not write the index out */
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/*
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* When reading only one tree (either the most basic form,
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* "-m ent" or "--reset ent" form), we can obtain a fully
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* valid cache-tree because the index must match exactly
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* what came from the tree.
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*/
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if (nr_trees == 1 && !opts.prefix)
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prime_cache_tree(&the_index, trees[0]);
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if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
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die("unable to write new index file");
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return 0;
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}
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