git/tree-diff.c
Linus Torvalds ac1b3d1248 Split up tree diff functions into tree-diff.c library
This makes the tree diff functionality independent of the "git-diff-tree"
program, by splitting the core functionality up into a library file.

This will be needed for when we teach git-rev-list to only follow a
specified set of pathnames, rather than the global revision history.

Most of it is a fairly straightforward code move, but it also involves
some calling convention cleanup, and moving some of the static variables
from diff-tree.c into the options structure.

The actual tree change callback routines also become paramterized by the
diff_options structure, allowing the library functionality to do something
else than just show the diff on stdout.

Right now the only user of this functionality remains git-diff-tree
itself.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-10-22 22:49:51 -07:00

271 lines
6.1 KiB
C

/*
* Helper functions for tree diff generation
*/
#include "cache.h"
#include "diff.h"
// What paths are we interested in?
static int nr_paths = 0;
static const char **paths = NULL;
static int *pathlens = NULL;
static void update_tree_entry(struct tree_desc *desc)
{
void *buf = desc->buf;
unsigned long size = desc->size;
int len = strlen(buf) + 1 + 20;
if (size < len)
die("corrupt tree file");
desc->buf = buf + len;
desc->size = size - len;
}
static const unsigned char *extract(struct tree_desc *desc, const char **pathp, unsigned int *modep)
{
void *tree = desc->buf;
unsigned long size = desc->size;
int len = strlen(tree)+1;
const unsigned char *sha1 = tree + len;
const char *path = strchr(tree, ' ');
unsigned int mode;
if (!path || size < len + 20 || sscanf(tree, "%o", &mode) != 1)
die("corrupt tree file");
*pathp = path+1;
*modep = DIFF_FILE_CANON_MODE(mode);
return sha1;
}
static char *malloc_base(const char *base, const char *path, int pathlen)
{
int baselen = strlen(base);
char *newbase = xmalloc(baselen + pathlen + 2);
memcpy(newbase, base, baselen);
memcpy(newbase + baselen, path, pathlen);
memcpy(newbase + baselen + pathlen, "/", 2);
return newbase;
}
static int show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base);
static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
{
unsigned mode1, mode2;
const char *path1, *path2;
const unsigned char *sha1, *sha2;
int cmp, pathlen1, pathlen2;
sha1 = extract(t1, &path1, &mode1);
sha2 = extract(t2, &path2, &mode2);
pathlen1 = strlen(path1);
pathlen2 = strlen(path2);
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 (!opt->find_copies_harder &&
!memcmp(sha1, sha2, 20) && 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;
}
if (opt->recursive && S_ISDIR(mode1)) {
int retval;
char *newbase = malloc_base(base, path1, pathlen1);
if (opt->tree_in_recursive)
opt->change(opt, mode1, mode2,
sha1, sha2, base, path1);
retval = diff_tree_sha1(sha1, sha2, newbase, opt);
free(newbase);
return retval;
}
opt->change(opt, mode1, mode2, sha1, sha2, base, path1);
return 0;
}
static int interesting(struct tree_desc *desc, const char *base)
{
const char *path;
unsigned mode;
int i;
int baselen, pathlen;
if (!nr_paths)
return 1;
(void)extract(desc, &path, &mode);
pathlen = strlen(path);
baselen = strlen(base);
for (i=0; i < nr_paths; i++) {
const char *match = paths[i];
int matchlen = pathlens[i];
if (baselen >= matchlen) {
/* If it doesn't match, move along... */
if (strncmp(base, match, matchlen))
continue;
/* The base is a subdirectory of a path which was specified. */
return 1;
}
/* Does the base match? */
if (strncmp(base, match, baselen))
continue;
match += baselen;
matchlen -= baselen;
if (pathlen > matchlen)
continue;
if (matchlen > pathlen) {
if (match[pathlen] != '/')
continue;
if (!S_ISDIR(mode))
continue;
}
if (strncmp(path, match, pathlen))
continue;
return 1;
}
return 0; /* No matches */
}
/* A whole sub-tree went away or appeared */
static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base)
{
while (desc->size) {
if (interesting(desc, base))
show_entry(opt, prefix, desc, base);
update_tree_entry(desc);
}
}
/* A file entry went away or appeared */
static int show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base)
{
unsigned mode;
const char *path;
const unsigned char *sha1 = extract(desc, &path, &mode);
if (opt->recursive && S_ISDIR(mode)) {
char type[20];
char *newbase = malloc_base(base, path, strlen(path));
struct tree_desc inner;
void *tree;
tree = read_sha1_file(sha1, type, &inner.size);
if (!tree || strcmp(type, "tree"))
die("corrupt tree sha %s", sha1_to_hex(sha1));
inner.buf = tree;
show_tree(opt, prefix, &inner, newbase);
free(tree);
free(newbase);
return 0;
}
opt->add_remove(opt, prefix[0], mode, sha1, base, path);
return 0;
}
int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
{
while (t1->size | t2->size) {
if (nr_paths && t1->size && !interesting(t1, base)) {
update_tree_entry(t1);
continue;
}
if (nr_paths && t2->size && !interesting(t2, base)) {
update_tree_entry(t2);
continue;
}
if (!t1->size) {
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");
}
return 0;
}
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;
int retval;
tree1 = read_object_with_reference(old, "tree", &t1.size, NULL);
if (!tree1)
die("unable to read source tree (%s)", sha1_to_hex(old));
tree2 = read_object_with_reference(new, "tree", &t2.size, NULL);
if (!tree2)
die("unable to read destination tree (%s)", sha1_to_hex(new));
t1.buf = tree1;
t2.buf = tree2;
retval = diff_tree(&t1, &t2, base, opt);
free(tree1);
free(tree2);
return retval;
}
static int count_paths(const char **paths)
{
int i = 0;
while (*paths++)
i++;
return i;
}
void diff_tree_setup_paths(const char **p)
{
if (p) {
int i;
paths = p;
nr_paths = count_paths(paths);
pathlens = xmalloc(nr_paths * sizeof(int));
for (i=0; i<nr_paths; i++)
pathlens[i] = strlen(paths[i]);
}
}