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https://github.com/git/git
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30ca07a249
When defined, this allows plumbing commands that update the index (add, apply, checkout-index, merge-recursive, mv, read-tree, rm, update-index, and write-tree) to write their resulting index to an alternative index file while holding a lock to the original index file. With this, git-commit that jumps the index does not have to make an extra copy of the index file, and more importantly, it can do the update while holding the lock on the index. However, I think the interface to let an environment variable specify the output is a mistake, as shown in the documentation. If a curious user has the environment variable set to something other than the file GIT_INDEX_FILE points at, almost everything will break. This should instead be a command line parameter to tell these plumbing commands to write the result in the named file, to prevent stupid mistakes. Signed-off-by: Junio C Hamano <junkio@cox.net>
274 lines
6.4 KiB
C
274 lines
6.4 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 "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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static struct object_list *trees;
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static int list_tree(unsigned char *sha1)
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{
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struct tree *tree = parse_tree_indirect(sha1);
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if (!tree)
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return -1;
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object_list_append(&tree->object, &trees);
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return 0;
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}
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static int read_cache_unmerged(void)
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{
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int i;
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struct cache_entry **dst;
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struct cache_entry *last = NULL;
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read_cache();
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dst = active_cache;
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for (i = 0; i < active_nr; i++) {
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struct cache_entry *ce = active_cache[i];
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if (ce_stage(ce)) {
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if (last && !strcmp(ce->name, last->name))
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continue;
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cache_tree_invalidate_path(active_cache_tree, ce->name);
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last = ce;
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ce->ce_mode = 0;
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ce->ce_flags &= ~htons(CE_STAGEMASK);
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}
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*dst++ = ce;
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}
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active_nr = dst - active_cache;
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return !!last;
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}
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static void prime_cache_tree_rec(struct cache_tree *it, struct tree *tree)
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{
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struct tree_desc desc;
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struct name_entry entry;
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int cnt;
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hashcpy(it->sha1, tree->object.sha1);
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init_tree_desc(&desc, tree->buffer, tree->size);
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cnt = 0;
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while (tree_entry(&desc, &entry)) {
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if (!S_ISDIR(entry.mode))
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cnt++;
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else {
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struct cache_tree_sub *sub;
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struct tree *subtree = lookup_tree(entry.sha1);
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if (!subtree->object.parsed)
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parse_tree(subtree);
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sub = cache_tree_sub(it, entry.path);
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sub->cache_tree = cache_tree();
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prime_cache_tree_rec(sub->cache_tree, subtree);
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cnt += sub->cache_tree->entry_count;
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}
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}
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it->entry_count = cnt;
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}
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static void prime_cache_tree(void)
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{
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struct tree *tree = (struct tree *)trees->item;
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if (!tree)
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return;
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active_cache_tree = cache_tree();
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prime_cache_tree_rec(active_cache_tree, tree);
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}
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static const char read_tree_usage[] = "git-read-tree (<sha> | [[-m [--aggressive] | --reset | --prefix=<prefix>] [-u | -i]] [--exclude-per-directory=<gitignore>] <sha1> [<sha2> [<sha3>]])";
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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, newfd, stage = 0;
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unsigned char sha1[20];
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struct unpack_trees_options opts;
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memset(&opts, 0, sizeof(opts));
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opts.head_idx = -1;
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setup_git_directory();
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git_config(git_default_config);
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newfd = hold_locked_index(&lock_file, 1);
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git_config(git_default_config);
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for (i = 1; i < argc; i++) {
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const char *arg = argv[i];
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/* "-u" means "update", meaning that a merge will update
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* the working tree.
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*/
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if (!strcmp(arg, "-u")) {
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opts.update = 1;
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continue;
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}
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if (!strcmp(arg, "-v")) {
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opts.verbose_update = 1;
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continue;
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}
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/* "-i" means "index only", meaning that a merge will
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* not even look at the working tree.
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*/
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if (!strcmp(arg, "-i")) {
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opts.index_only = 1;
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continue;
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}
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/* "--prefix=<subdirectory>/" means keep the current index
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* entries and put the entries from the tree under the
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* given subdirectory.
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*/
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if (!prefixcmp(arg, "--prefix=")) {
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if (stage || opts.merge || opts.prefix)
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usage(read_tree_usage);
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opts.prefix = arg + 9;
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opts.merge = 1;
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stage = 1;
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if (read_cache_unmerged())
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die("you need to resolve your current index first");
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continue;
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}
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/* This differs from "-m" in that we'll silently ignore
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* unmerged entries and overwrite working tree files that
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* correspond to them.
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*/
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if (!strcmp(arg, "--reset")) {
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if (stage || opts.merge || opts.prefix)
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usage(read_tree_usage);
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opts.reset = 1;
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opts.merge = 1;
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stage = 1;
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read_cache_unmerged();
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continue;
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}
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if (!strcmp(arg, "--trivial")) {
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opts.trivial_merges_only = 1;
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continue;
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}
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if (!strcmp(arg, "--aggressive")) {
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opts.aggressive = 1;
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continue;
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}
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/* "-m" stands for "merge", meaning we start in stage 1 */
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if (!strcmp(arg, "-m")) {
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if (stage || opts.merge || opts.prefix)
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usage(read_tree_usage);
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if (read_cache_unmerged())
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die("you need to resolve your current index first");
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stage = 1;
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opts.merge = 1;
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continue;
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}
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if (!prefixcmp(arg, "--exclude-per-directory=")) {
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struct dir_struct *dir;
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if (opts.dir)
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die("more than one --exclude-per-directory are given.");
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dir = xcalloc(1, sizeof(*opts.dir));
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dir->show_ignored = 1;
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dir->exclude_per_dir = arg + 24;
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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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continue;
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}
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/* using -u and -i at the same time makes no sense */
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if (1 < opts.index_only + opts.update)
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usage(read_tree_usage);
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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 ((opts.update||opts.index_only) && !opts.merge)
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usage(read_tree_usage);
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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.prefix) {
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int pfxlen = strlen(opts.prefix);
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int pos;
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if (opts.prefix[pfxlen-1] != '/')
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die("prefix must end with /");
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if (stage != 2)
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die("binding merge takes only one tree");
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pos = cache_name_pos(opts.prefix, pfxlen);
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if (0 <= pos)
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die("corrupt index file");
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pos = -pos-1;
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if (pos < active_nr &&
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!strncmp(active_cache[pos]->name, opts.prefix, pfxlen))
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die("subdirectory '%s' already exists.", opts.prefix);
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pos = cache_name_pos(opts.prefix, pfxlen-1);
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if (0 <= pos)
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die("file '%.*s' already exists.",
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pfxlen-1, opts.prefix);
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}
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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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break;
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case 3:
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default:
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opts.fn = threeway_merge;
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cache_tree_free(&active_cache_tree);
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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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unpack_trees(trees, &opts);
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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 (trees && trees->item && !opts.prefix && (!opts.merge || (stage == 2))) {
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cache_tree_free(&active_cache_tree);
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prime_cache_tree();
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}
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if (write_cache(newfd, active_cache, active_nr) ||
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close(newfd) || commit_locked_index(&lock_file))
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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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