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![Junio C Hamano](/assets/img/avatar_default.png)
Traditionally, the --ignore-whitespace* options have merely meant to tell the diff output routine that some class of differences are not worth showing in the textual diff output, so that the end user has easier time to review the remaining (presumably more meaningful) changes. These options never affected the outcome of the command, given as the exit status when the --exit-code option was in effect (either directly or indirectly). When you have only whitespace changes, however, you might expect git diff -b --exit-code to report that there is _no_ change with zero exit status. Change the semantics of --ignore-whitespace* options to mean more than "omit showing the difference in text". The exit status, when --exit-code is in effect, is computed by checking if we found any differences at the path level, while diff frontends feed filepairs to the diffcore engine. When "ignore whitespace" options are in effect, we defer this determination until the very end of diffcore transformation. We simply do not know until the textual diff is generated, which comes very late in the pipeline. When --quiet is in effect, various diff frontends optimize by breaking out early from the loop that enumerates the filepairs, when we find the first path level difference; when --ignore-whitespace* is used the above change automatically disables this optimization. Signed-off-by: Junio C Hamano <gitster@pobox.com>
476 lines
12 KiB
C
476 lines
12 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 "diffcore.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 char *malloc_fullname(const char *base, int baselen, const char *path, int pathlen)
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{
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char *fullname = xmalloc(baselen + pathlen + 1);
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memcpy(fullname, base, baselen);
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memcpy(fullname + baselen, path, pathlen);
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fullname[baselen + pathlen] = 0;
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return fullname;
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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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char *fullname;
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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 (!DIFF_OPT_TST(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 (DIFF_OPT_TST(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 (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
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newbase[baselen + pathlen1] = 0;
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opt->change(opt, mode1, mode2,
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sha1, sha2, newbase);
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newbase[baselen + pathlen1] = '/';
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}
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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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fullname = malloc_fullname(base, baselen, path1, pathlen1);
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opt->change(opt, mode1, mode2, sha1, sha2, fullname);
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free(fullname);
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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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* - 2 for "yes, and all subsequent entries will be"
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* - 1 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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/*
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* If the base is a subdirectory of a path which
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* was specified, all of them are interesting.
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*/
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if (!matchlen ||
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base[matchlen] == '/' ||
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match[matchlen - 1] == '/')
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return 2;
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/* Just a random prefix match */
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continue;
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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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int all_interesting = 0;
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while (desc->size) {
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int show;
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if (all_interesting)
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show = 1;
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else {
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show = tree_entry_interesting(desc, base, baselen,
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opt);
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if (show == 2)
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all_interesting = 1;
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}
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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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int pathlen = tree_entry_len(path, sha1);
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if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
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enum object_type type;
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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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if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
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newbase[baselen + pathlen] = 0;
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opt->add_remove(opt, *prefix, mode, sha1, newbase);
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newbase[baselen + pathlen] = '/';
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}
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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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char *fullname = malloc_fullname(base, baselen, path, pathlen);
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opt->add_remove(opt, prefix[0], mode, sha1, fullname);
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free(fullname);
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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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int all_interesting = 0;
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while (t->size) {
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int show;
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if (all_interesting)
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show = 1;
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else {
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show = tree_entry_interesting(t, base, baselen, opt);
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if (show == 2)
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all_interesting = 1;
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}
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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 (DIFF_OPT_TST(opt, QUIET) &&
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DIFF_OPT_TST(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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/*
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* Does it look like the resulting diff might be due to a rename?
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* - single entry
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* - not a valid previous file
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*/
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static inline int diff_might_be_rename(void)
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{
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return diff_queued_diff.nr == 1 &&
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!DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
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}
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static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
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{
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struct diff_options diff_opts;
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struct diff_queue_struct *q = &diff_queued_diff;
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struct diff_filepair *choice;
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const char *paths[1];
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int i;
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/* Remove the file creation entry from the diff queue, and remember it */
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choice = q->queue[0];
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q->nr = 0;
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diff_setup(&diff_opts);
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DIFF_OPT_SET(&diff_opts, RECURSIVE);
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diff_opts.detect_rename = DIFF_DETECT_RENAME;
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diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
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diff_opts.single_follow = opt->paths[0];
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diff_opts.break_opt = opt->break_opt;
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paths[0] = NULL;
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diff_tree_setup_paths(paths, &diff_opts);
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if (diff_setup_done(&diff_opts) < 0)
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die("unable to set up diff options to follow renames");
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diff_tree(t1, t2, base, &diff_opts);
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diffcore_std(&diff_opts);
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diff_tree_release_paths(&diff_opts);
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/* Go through the new set of filepairing, and see if we find a more interesting one */
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for (i = 0; i < q->nr; i++) {
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struct diff_filepair *p = q->queue[i];
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/*
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* Found a source? Not only do we use that for the new
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* diff_queued_diff, we will also use that as the path in
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* the future!
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*/
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if ((p->status == 'R' || p->status == 'C') && !strcmp(p->two->path, opt->paths[0])) {
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/* Switch the file-pairs around */
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q->queue[i] = choice;
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choice = p;
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/* Update the path we use from now on.. */
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diff_tree_release_paths(opt);
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opt->paths[0] = xstrdup(p->one->path);
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diff_tree_setup_paths(opt->paths, opt);
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break;
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}
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}
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/*
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* Then, discard all the non-relevant file pairs...
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*/
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for (i = 0; i < q->nr; i++) {
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struct diff_filepair *p = q->queue[i];
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diff_free_filepair(p);
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}
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/*
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* .. and re-instate the one we want (which might be either the
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* original one, or the rename/copy we found)
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*/
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q->queue[0] = choice;
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q->nr = 1;
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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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if (DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
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init_tree_desc(&t1, tree1, size1);
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init_tree_desc(&t2, tree2, size2);
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try_to_follow_renames(&t1, &t2, base, opt);
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}
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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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