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tag: v1.7.9
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/*
* Helper functions for tree diff generation
*/
#include "cache.h"
#include "diff.h"
#include "diffcore.h"
#include "tree.h"

static void show_entry(struct diff_options *opt, const char *prefix,
struct tree_desc *desc, struct strbuf *base);

static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2,
struct strbuf *base, struct diff_options *opt)
{
unsigned mode1, mode2;
const char *path1, *path2;
const unsigned char *sha1, *sha2;
int cmp, pathlen1, pathlen2;
int old_baselen = base->len;

sha1 = tree_entry_extract(t1, &path1, &mode1);
sha2 = tree_entry_extract(t2, &path2, &mode2);

pathlen1 = tree_entry_len(&t1->entry);
pathlen2 = tree_entry_len(&t2->entry);
cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
if (cmp < 0) {
show_entry(opt, "-", t1, base);
return -1;
}
if (cmp > 0) {
show_entry(opt, "+", t2, base);
return 1;
}
if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) && !hashcmp(sha1, sha2) && mode1 == mode2)
return 0;

/*
* If the filemode has changed to/from a directory from/to a regular
* file, we need to consider it a remove and an add.
*/
if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
show_entry(opt, "-", t1, base);
show_entry(opt, "+", t2, base);
return 0;
}

strbuf_add(base, path1, pathlen1);
if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode1)) {
if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
opt->change(opt, mode1, mode2,
sha1, sha2, base->buf, 0, 0);
}
strbuf_addch(base, '/');
diff_tree_sha1(sha1, sha2, base->buf, opt);
} else {
opt->change(opt, mode1, mode2, sha1, sha2, base->buf, 0, 0);
}
strbuf_setlen(base, old_baselen);
return 0;
}

/* A whole sub-tree went away or appeared */
static void show_tree(struct diff_options *opt, const char *prefix,
struct tree_desc *desc, struct strbuf *base)
{
enum interesting match = entry_not_interesting;
for (; desc->size; update_tree_entry(desc)) {
if (match != all_entries_interesting) {
match = tree_entry_interesting(&desc->entry, base, 0,
&opt->pathspec);
if (match == all_entries_not_interesting)
break;
if (match == entry_not_interesting)
continue;
}
show_entry(opt, prefix, desc, base);
}
}

/* A file entry went away or appeared */
static void show_entry(struct diff_options *opt, const char *prefix,
struct tree_desc *desc, struct strbuf *base)
{
unsigned mode;
const char *path;
const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
int pathlen = tree_entry_len(&desc->entry);
int old_baselen = base->len;

strbuf_add(base, path, pathlen);
if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
enum object_type type;
struct tree_desc inner;
void *tree;
unsigned long size;

tree = read_sha1_file(sha1, &type, &size);
if (!tree || type != OBJ_TREE)
die("corrupt tree sha %s", sha1_to_hex(sha1));

if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE))
opt->add_remove(opt, *prefix, mode, sha1, base->buf, 0);

strbuf_addch(base, '/');

init_tree_desc(&inner, tree, size);
show_tree(opt, prefix, &inner, base);
free(tree);
} else
opt->add_remove(opt, prefix[0], mode, sha1, base->buf, 0);

strbuf_setlen(base, old_baselen);
}

static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
struct diff_options *opt,
enum interesting *match)
{
while (t->size) {
*match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
if (*match) {
if (*match == all_entries_not_interesting)
t->size = 0;
break;
}
update_tree_entry(t);
}
}

int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
const char *base_str, struct diff_options *opt)
{
struct strbuf base;
int baselen = strlen(base_str);
enum interesting t1_match = entry_not_interesting;
enum interesting t2_match = entry_not_interesting;

/* Enable recursion indefinitely */
opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
opt->pathspec.max_depth = -1;

strbuf_init(&base, PATH_MAX);
strbuf_add(&base, base_str, baselen);

for (;;) {
if (diff_can_quit_early(opt))
break;
if (opt->pathspec.nr) {
skip_uninteresting(t1, &base, opt, &t1_match);
skip_uninteresting(t2, &base, opt, &t2_match);
}
if (!t1->size) {
if (!t2->size)
break;
show_entry(opt, "+", t2, &base);
update_tree_entry(t2);
continue;
}
if (!t2->size) {
show_entry(opt, "-", t1, &base);
update_tree_entry(t1);
continue;
}
switch (compare_tree_entry(t1, t2, &base, opt)) {
case -1:
update_tree_entry(t1);
continue;
case 0:
update_tree_entry(t1);
/* Fallthrough */
case 1:
update_tree_entry(t2);
continue;
}
die("git diff-tree: internal error");
}

strbuf_release(&base);
return 0;
}

/*
* Does it look like the resulting diff might be due to a rename?
* - single entry
* - not a valid previous file
*/
static inline int diff_might_be_rename(void)
{
return diff_queued_diff.nr == 1 &&
!DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
}

static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
{
struct diff_options diff_opts;
struct diff_queue_struct *q = &diff_queued_diff;
struct diff_filepair *choice;
const char *paths[1];
int i;

/* Remove the file creation entry from the diff queue, and remember it */
choice = q->queue[0];
q->nr = 0;

diff_setup(&diff_opts);
DIFF_OPT_SET(&diff_opts, RECURSIVE);
DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
diff_opts.single_follow = opt->pathspec.raw[0];
diff_opts.break_opt = opt->break_opt;
diff_opts.rename_score = opt->rename_score;
paths[0] = NULL;
diff_tree_setup_paths(paths, &diff_opts);
if (diff_setup_done(&diff_opts) < 0)
die("unable to set up diff options to follow renames");
diff_tree(t1, t2, base, &diff_opts);
diffcore_std(&diff_opts);
diff_tree_release_paths(&diff_opts);

/* Go through the new set of filepairing, and see if we find a more interesting one */
opt->found_follow = 0;
for (i = 0; i < q->nr; i++) {
struct diff_filepair *p = q->queue[i];

/*
* Found a source? Not only do we use that for the new
* diff_queued_diff, we will also use that as the path in
* the future!
*/
if ((p->status == 'R' || p->status == 'C') &&
!strcmp(p->two->path, opt->pathspec.raw[0])) {
/* Switch the file-pairs around */
q->queue[i] = choice;
choice = p;

/* Update the path we use from now on.. */
diff_tree_release_paths(opt);
opt->pathspec.raw[0] = xstrdup(p->one->path);
diff_tree_setup_paths(opt->pathspec.raw, opt);

/*
* The caller expects us to return a set of vanilla
* filepairs to let a later call to diffcore_std()
* it makes to sort the renames out (among other
* things), but we already have found renames
* ourselves; signal diffcore_std() not to muck with
* rename information.
*/
opt->found_follow = 1;
break;
}
}

/*
* Then, discard all the non-relevant file pairs...
*/
for (i = 0; i < q->nr; i++) {
struct diff_filepair *p = q->queue[i];
diff_free_filepair(p);
}

/*
* .. and re-instate the one we want (which might be either the
* original one, or the rename/copy we found)
*/
q->queue[0] = choice;
q->nr = 1;
}

int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
{
void *tree1, *tree2;
struct tree_desc t1, t2;
unsigned long size1, size2;
int retval;

tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
if (!tree1)
die("unable to read source tree (%s)", sha1_to_hex(old));
tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
if (!tree2)
die("unable to read destination tree (%s)", sha1_to_hex(new));
init_tree_desc(&t1, tree1, size1);
init_tree_desc(&t2, tree2, size2);
retval = diff_tree(&t1, &t2, base, opt);
if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
init_tree_desc(&t1, tree1, size1);
init_tree_desc(&t2, tree2, size2);
try_to_follow_renames(&t1, &t2, base, opt);
}
free(tree1);
free(tree2);
return retval;
}

int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
{
int retval;
void *tree;
unsigned long size;
struct tree_desc empty, real;

tree = read_object_with_reference(new, tree_type, &size, NULL);
if (!tree)
die("unable to read root tree (%s)", sha1_to_hex(new));
init_tree_desc(&real, tree, size);

init_tree_desc(&empty, "", 0);
retval = diff_tree(&empty, &real, base, opt);
free(tree);
return retval;
}

void diff_tree_release_paths(struct diff_options *opt)
{
free_pathspec(&opt->pathspec);
}

void diff_tree_setup_paths(const char **p, struct diff_options *opt)
{
init_pathspec(&opt->pathspec, p);
}
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