mirror of
https://github.com/git/git.git
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ccc744abbb
If we already know that some of the pathspecs can match later entries in the tree we are looking at, we do not have to do more expensive strncmp() upfront before comparing the length of the match pattern and the path, as a path longer than the match pattern will not match it, and a path shorter than the match pattern will match only if the path is a directory-component wise prefix of the match pattern. Signed-off-by: Junio C Hamano <junkio@cox.net>
342 lines
8.3 KiB
C
342 lines
8.3 KiB
C
/*
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* Helper functions for tree diff generation
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*/
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#include "cache.h"
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#include "diff.h"
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#include "tree.h"
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static char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
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{
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char *newbase = xmalloc(baselen + pathlen + 2);
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memcpy(newbase, base, baselen);
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memcpy(newbase + baselen, path, pathlen);
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memcpy(newbase + baselen + pathlen, "/", 2);
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return newbase;
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}
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static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
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const char *base, int baselen);
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static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
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{
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unsigned mode1, mode2;
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const char *path1, *path2;
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const unsigned char *sha1, *sha2;
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int cmp, pathlen1, pathlen2;
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sha1 = tree_entry_extract(t1, &path1, &mode1);
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sha2 = tree_entry_extract(t2, &path2, &mode2);
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pathlen1 = tree_entry_len(path1, sha1);
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pathlen2 = tree_entry_len(path2, sha2);
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cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
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if (cmp < 0) {
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show_entry(opt, "-", t1, base, baselen);
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return -1;
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}
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if (cmp > 0) {
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show_entry(opt, "+", t2, base, baselen);
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return 1;
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}
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if (!opt->find_copies_harder && !hashcmp(sha1, sha2) && mode1 == mode2)
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return 0;
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/*
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* If the filemode has changed to/from a directory from/to a regular
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* file, we need to consider it a remove and an add.
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*/
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if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
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show_entry(opt, "-", t1, base, baselen);
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show_entry(opt, "+", t2, base, baselen);
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return 0;
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}
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if (opt->recursive && S_ISDIR(mode1)) {
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int retval;
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char *newbase = malloc_base(base, baselen, path1, pathlen1);
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if (opt->tree_in_recursive)
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opt->change(opt, mode1, mode2,
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sha1, sha2, base, path1);
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retval = diff_tree_sha1(sha1, sha2, newbase, opt);
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free(newbase);
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return retval;
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}
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opt->change(opt, mode1, mode2, sha1, sha2, base, path1);
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return 0;
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}
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/*
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* Is a tree entry interesting given the pathspec we have?
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*
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* Return:
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* - positive for yes
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* - zero for no
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* - negative for "no, and no subsequent entries will be either"
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*/
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static int tree_entry_interesting(struct tree_desc *desc, const char *base, int baselen, struct diff_options *opt)
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{
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const char *path;
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const unsigned char *sha1;
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unsigned mode;
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int i;
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int pathlen;
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int never_interesting = -1;
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if (!opt->nr_paths)
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return 1;
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sha1 = tree_entry_extract(desc, &path, &mode);
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pathlen = tree_entry_len(path, sha1);
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for (i = 0; i < opt->nr_paths; i++) {
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const char *match = opt->paths[i];
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int matchlen = opt->pathlens[i];
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int m = -1; /* signals that we haven't called strncmp() */
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if (baselen >= matchlen) {
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/* If it doesn't match, move along... */
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if (strncmp(base, match, matchlen))
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continue;
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/* The base is a subdirectory of a path which was specified. */
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return 1;
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}
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/* Does the base match? */
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if (strncmp(base, match, baselen))
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continue;
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match += baselen;
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matchlen -= baselen;
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if (never_interesting) {
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/*
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* We have not seen any match that sorts later
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* than the current path.
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*/
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/*
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* Does match sort strictly earlier than path
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* with their common parts?
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*/
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m = strncmp(match, path,
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(matchlen < pathlen) ? matchlen : pathlen);
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if (m < 0)
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continue;
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/*
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* If we come here even once, that means there is at
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* least one pathspec that would sort equal to or
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* later than the path we are currently looking at.
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* In other words, if we have never reached this point
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* after iterating all pathspecs, it means all
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* pathspecs are either outside of base, or inside the
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* base but sorts strictly earlier than the current
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* one. In either case, they will never match the
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* subsequent entries. In such a case, we initialized
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* the variable to -1 and that is what will be
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* returned, allowing the caller to terminate early.
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*/
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never_interesting = 0;
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}
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if (pathlen > matchlen)
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continue;
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if (matchlen > pathlen) {
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if (match[pathlen] != '/')
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continue;
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if (!S_ISDIR(mode))
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continue;
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}
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if (m == -1)
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/*
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* we cheated and did not do strncmp(), so we do
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* that here.
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*/
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m = strncmp(match, path, pathlen);
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/*
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* If common part matched earlier then it is a hit,
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* because we rejected the case where path is not a
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* leading directory and is shorter than match.
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*/
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if (!m)
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return 1;
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}
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return never_interesting; /* No matches */
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}
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/* A whole sub-tree went away or appeared */
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static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
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{
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while (desc->size) {
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int show = tree_entry_interesting(desc, base, baselen, opt);
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if (show < 0)
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break;
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if (show)
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show_entry(opt, prefix, desc, base, baselen);
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update_tree_entry(desc);
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}
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}
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/* A file entry went away or appeared */
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static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
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const char *base, int baselen)
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{
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unsigned mode;
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const char *path;
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const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
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if (opt->recursive && S_ISDIR(mode)) {
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enum object_type type;
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int pathlen = tree_entry_len(path, sha1);
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char *newbase = malloc_base(base, baselen, path, pathlen);
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struct tree_desc inner;
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void *tree;
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unsigned long size;
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tree = read_sha1_file(sha1, &type, &size);
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if (!tree || type != OBJ_TREE)
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die("corrupt tree sha %s", sha1_to_hex(sha1));
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init_tree_desc(&inner, tree, size);
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show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
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free(tree);
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free(newbase);
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} else {
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opt->add_remove(opt, prefix[0], mode, sha1, base, path);
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}
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}
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static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
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{
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while (t->size) {
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int show = tree_entry_interesting(t, base, baselen, opt);
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if (!show) {
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update_tree_entry(t);
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continue;
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}
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/* Skip it all? */
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if (show < 0)
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t->size = 0;
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return;
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}
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}
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int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
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{
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int baselen = strlen(base);
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for (;;) {
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if (opt->quiet && opt->has_changes)
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break;
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if (opt->nr_paths) {
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skip_uninteresting(t1, base, baselen, opt);
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skip_uninteresting(t2, base, baselen, opt);
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}
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if (!t1->size) {
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if (!t2->size)
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break;
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show_entry(opt, "+", t2, base, baselen);
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update_tree_entry(t2);
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continue;
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}
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if (!t2->size) {
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show_entry(opt, "-", t1, base, baselen);
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update_tree_entry(t1);
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continue;
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}
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switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
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case -1:
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update_tree_entry(t1);
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continue;
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case 0:
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update_tree_entry(t1);
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/* Fallthrough */
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case 1:
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update_tree_entry(t2);
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continue;
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}
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die("git-diff-tree: internal error");
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}
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return 0;
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}
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int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
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{
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void *tree1, *tree2;
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struct tree_desc t1, t2;
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unsigned long size1, size2;
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int retval;
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tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
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if (!tree1)
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die("unable to read source tree (%s)", sha1_to_hex(old));
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tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
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if (!tree2)
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die("unable to read destination tree (%s)", sha1_to_hex(new));
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init_tree_desc(&t1, tree1, size1);
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init_tree_desc(&t2, tree2, size2);
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retval = diff_tree(&t1, &t2, base, opt);
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free(tree1);
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free(tree2);
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return retval;
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}
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int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
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{
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int retval;
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void *tree;
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unsigned long size;
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struct tree_desc empty, real;
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tree = read_object_with_reference(new, tree_type, &size, NULL);
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if (!tree)
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die("unable to read root tree (%s)", sha1_to_hex(new));
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init_tree_desc(&real, tree, size);
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init_tree_desc(&empty, "", 0);
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retval = diff_tree(&empty, &real, base, opt);
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free(tree);
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return retval;
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}
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static int count_paths(const char **paths)
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{
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int i = 0;
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while (*paths++)
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i++;
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return i;
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}
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void diff_tree_release_paths(struct diff_options *opt)
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{
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free(opt->pathlens);
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}
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void diff_tree_setup_paths(const char **p, struct diff_options *opt)
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{
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opt->nr_paths = 0;
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opt->pathlens = NULL;
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opt->paths = NULL;
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if (p) {
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int i;
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opt->paths = p;
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opt->nr_paths = count_paths(p);
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if (opt->nr_paths == 0) {
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opt->pathlens = NULL;
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return;
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}
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opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
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for (i=0; i < opt->nr_paths; i++)
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opt->pathlens[i] = strlen(p[i]);
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}
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}
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