git/read-tree.c
Junio C Hamano 340e4f88c0 Remove empty directories after read-tree -u.
This fixes everybody's favorite gripe that switching branche with
'git checkout' leaves empty directories.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-10-10 17:34:08 -07:00

727 lines
16 KiB
C

/*
* GIT - The information manager from hell
*
* Copyright (C) Linus Torvalds, 2005
*/
#define DBRT_DEBUG 1
#include "cache.h"
#include "object.h"
#include "tree.h"
static int merge = 0;
static int update = 0;
static int index_only = 0;
static int nontrivial_merge = 0;
static int trivial_merges_only = 0;
static int head_idx = -1;
static int merge_size = 0;
static struct object_list *trees = NULL;
static struct cache_entry df_conflict_entry = {
};
static struct tree_entry_list df_conflict_list = {
.name = NULL,
.next = &df_conflict_list
};
typedef int (*merge_fn_t)(struct cache_entry **src);
static int entcmp(char *name1, int dir1, char *name2, int dir2)
{
int len1 = strlen(name1);
int len2 = strlen(name2);
int len = len1 < len2 ? len1 : len2;
int ret = memcmp(name1, name2, len);
unsigned char c1, c2;
if (ret)
return ret;
c1 = name1[len];
c2 = name2[len];
if (!c1 && dir1)
c1 = '/';
if (!c2 && dir2)
c2 = '/';
ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
if (c1 && c2 && !ret)
ret = len1 - len2;
return ret;
}
static int unpack_trees_rec(struct tree_entry_list **posns, int len,
const char *base, merge_fn_t fn, int *indpos)
{
int baselen = strlen(base);
int src_size = len + 1;
do {
int i;
char *first;
int firstdir = 0;
int pathlen;
unsigned ce_size;
struct tree_entry_list **subposns;
struct cache_entry **src;
int any_files = 0;
int any_dirs = 0;
char *cache_name;
int ce_stage;
/* Find the first name in the input. */
first = NULL;
cache_name = NULL;
/* Check the cache */
if (merge && *indpos < active_nr) {
/* This is a bit tricky: */
/* If the index has a subdirectory (with
* contents) as the first name, it'll get a
* filename like "foo/bar". But that's after
* "foo", so the entry in trees will get
* handled first, at which point we'll go into
* "foo", and deal with "bar" from the index,
* because the base will be "foo/". The only
* way we can actually have "foo/bar" first of
* all the things is if the trees don't
* contain "foo" at all, in which case we'll
* handle "foo/bar" without going into the
* directory, but that's fine (and will return
* an error anyway, with the added unknown
* file case.
*/
cache_name = active_cache[*indpos]->name;
if (strlen(cache_name) > baselen &&
!memcmp(cache_name, base, baselen)) {
cache_name += baselen;
first = cache_name;
} else {
cache_name = NULL;
}
}
#if DBRT_DEBUG > 1
if (first)
printf("index %s\n", first);
#endif
for (i = 0; i < len; i++) {
if (!posns[i] || posns[i] == &df_conflict_list)
continue;
#if DBRT_DEBUG > 1
printf("%d %s\n", i + 1, posns[i]->name);
#endif
if (!first || entcmp(first, firstdir,
posns[i]->name,
posns[i]->directory) > 0) {
first = posns[i]->name;
firstdir = posns[i]->directory;
}
}
/* No name means we're done */
if (!first)
return 0;
pathlen = strlen(first);
ce_size = cache_entry_size(baselen + pathlen);
src = xmalloc(sizeof(struct cache_entry *) * src_size);
memset(src, 0, sizeof(struct cache_entry *) * src_size);
subposns = xmalloc(sizeof(struct tree_list_entry *) * len);
memset(subposns, 0, sizeof(struct tree_list_entry *) * len);
if (cache_name && !strcmp(cache_name, first)) {
any_files = 1;
src[0] = active_cache[*indpos];
remove_cache_entry_at(*indpos);
}
for (i = 0; i < len; i++) {
struct cache_entry *ce;
if (!posns[i] ||
(posns[i] != &df_conflict_list &&
strcmp(first, posns[i]->name))) {
continue;
}
if (posns[i] == &df_conflict_list) {
src[i + merge] = &df_conflict_entry;
continue;
}
if (posns[i]->directory) {
any_dirs = 1;
parse_tree(posns[i]->item.tree);
subposns[i] = posns[i]->item.tree->entries;
posns[i] = posns[i]->next;
src[i + merge] = &df_conflict_entry;
continue;
}
if (!merge)
ce_stage = 0;
else if (i + 1 < head_idx)
ce_stage = 1;
else if (i + 1 > head_idx)
ce_stage = 3;
else
ce_stage = 2;
ce = xmalloc(ce_size);
memset(ce, 0, ce_size);
ce->ce_mode = create_ce_mode(posns[i]->mode);
ce->ce_flags = create_ce_flags(baselen + pathlen,
ce_stage);
memcpy(ce->name, base, baselen);
memcpy(ce->name + baselen, first, pathlen + 1);
any_files = 1;
memcpy(ce->sha1, posns[i]->item.any->sha1, 20);
src[i + merge] = ce;
subposns[i] = &df_conflict_list;
posns[i] = posns[i]->next;
}
if (any_files) {
if (merge) {
int ret;
#if DBRT_DEBUG > 1
printf("%s:\n", first);
for (i = 0; i < src_size; i++) {
printf(" %d ", i);
if (src[i])
printf("%s\n", sha1_to_hex(src[i]->sha1));
else
printf("\n");
}
#endif
ret = fn(src);
#if DBRT_DEBUG > 1
printf("Added %d entries\n", ret);
#endif
*indpos += ret;
} else {
for (i = 0; i < src_size; i++) {
if (src[i]) {
add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
}
}
}
}
if (any_dirs) {
char *newbase = xmalloc(baselen + 2 + pathlen);
memcpy(newbase, base, baselen);
memcpy(newbase + baselen, first, pathlen);
newbase[baselen + pathlen] = '/';
newbase[baselen + pathlen + 1] = '\0';
if (unpack_trees_rec(subposns, len, newbase, fn,
indpos))
return -1;
free(newbase);
}
free(subposns);
free(src);
} while (1);
}
static void reject_merge(struct cache_entry *ce)
{
die("Entry '%s' would be overwritten by merge. Cannot merge.",
ce->name);
}
/* Unlink the last component and attempt to remove leading
* directories, in case this unlink is the removal of the
* last entry in the directory -- empty directories are removed.
*/
static void unlink_entry(char *name)
{
char *cp, *prev;
if (unlink(name))
return;
prev = NULL;
while (1) {
int status;
cp = strrchr(name, '/');
if (prev)
*prev = '/';
if (!cp)
break;
*cp = 0;
status = rmdir(name);
if (status) {
*cp = '/';
break;
}
prev = cp;
}
}
static void check_updates(struct cache_entry **src, int nr)
{
static struct checkout state = {
.base_dir = "",
.force = 1,
.quiet = 1,
.refresh_cache = 1,
};
unsigned short mask = htons(CE_UPDATE);
while (nr--) {
struct cache_entry *ce = *src++;
if (!ce->ce_mode) {
if (update)
unlink_entry(ce->name);
continue;
}
if (ce->ce_flags & mask) {
ce->ce_flags &= ~mask;
if (update)
checkout_entry(ce, &state);
}
}
}
static int unpack_trees(merge_fn_t fn)
{
int indpos = 0;
unsigned len = object_list_length(trees);
struct tree_entry_list **posns =
xmalloc(len * sizeof(struct tree_entry_list *));
int i;
struct object_list *posn = trees;
merge_size = len;
for (i = 0; i < len; i++) {
posns[i] = ((struct tree *) posn->item)->entries;
posn = posn->next;
}
if (unpack_trees_rec(posns, len, "", fn, &indpos))
return -1;
if (trivial_merges_only && nontrivial_merge)
die("Merge requires file-level merging");
check_updates(active_cache, active_nr);
return 0;
}
static int list_tree(unsigned char *sha1)
{
struct tree *tree = parse_tree_indirect(sha1);
if (!tree)
return -1;
object_list_append(&tree->object, &trees);
return 0;
}
static int same(struct cache_entry *a, struct cache_entry *b)
{
if (!!a != !!b)
return 0;
if (!a && !b)
return 1;
return a->ce_mode == b->ce_mode &&
!memcmp(a->sha1, b->sha1, 20);
}
/*
* When a CE gets turned into an unmerged entry, we
* want it to be up-to-date
*/
static void verify_uptodate(struct cache_entry *ce)
{
struct stat st;
if (index_only)
return;
if (!lstat(ce->name, &st)) {
unsigned changed = ce_match_stat(ce, &st);
if (!changed)
return;
errno = 0;
}
if (errno == ENOENT)
return;
die("Entry '%s' not uptodate. Cannot merge.", ce->name);
}
static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
{
merge->ce_flags |= htons(CE_UPDATE);
if (old) {
/*
* See if we can re-use the old CE directly?
* That way we get the uptodate stat info.
*
* This also removes the UPDATE flag on
* a match.
*/
if (same(old, merge)) {
*merge = *old;
} else {
verify_uptodate(old);
}
}
merge->ce_flags &= ~htons(CE_STAGEMASK);
add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
return 1;
}
static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
{
if (old)
verify_uptodate(old);
ce->ce_mode = 0;
add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
return 1;
}
static int keep_entry(struct cache_entry *ce)
{
add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
return 1;
}
#if DBRT_DEBUG
static void show_stage_entry(FILE *o,
const char *label, const struct cache_entry *ce)
{
if (!ce)
fprintf(o, "%s (missing)\n", label);
else
fprintf(o, "%s%06o %s %d\t%s\n",
label,
ntohl(ce->ce_mode),
sha1_to_hex(ce->sha1),
ce_stage(ce),
ce->name);
}
#endif
static int threeway_merge(struct cache_entry **stages)
{
struct cache_entry *index;
struct cache_entry *head;
struct cache_entry *remote = stages[head_idx + 1];
int count;
int head_match = 0;
int remote_match = 0;
int df_conflict_head = 0;
int df_conflict_remote = 0;
int any_anc_missing = 0;
int i;
for (i = 1; i < head_idx; i++) {
if (!stages[i])
any_anc_missing = 1;
}
index = stages[0];
head = stages[head_idx];
if (head == &df_conflict_entry) {
df_conflict_head = 1;
head = NULL;
}
if (remote == &df_conflict_entry) {
df_conflict_remote = 1;
remote = NULL;
}
/* First, if there's a #16 situation, note that to prevent #13
* and #14.
*/
if (!same(remote, head)) {
for (i = 1; i < head_idx; i++) {
if (same(stages[i], head)) {
head_match = i;
}
if (same(stages[i], remote)) {
remote_match = i;
}
}
}
/* We start with cases where the index is allowed to match
* something other than the head: #14(ALT) and #2ALT, where it
* is permitted to match the result instead.
*/
/* #14, #14ALT, #2ALT */
if (remote && !df_conflict_head && head_match && !remote_match) {
if (index && !same(index, remote) && !same(index, head))
reject_merge(index);
return merged_entry(remote, index);
}
/*
* If we have an entry in the index cache, then we want to
* make sure that it matches head.
*/
if (index && !same(index, head)) {
reject_merge(index);
}
if (head) {
/* #5ALT, #15 */
if (same(head, remote))
return merged_entry(head, index);
/* #13, #3ALT */
if (!df_conflict_remote && remote_match && !head_match)
return merged_entry(head, index);
}
/* #1 */
if (!head && !remote && any_anc_missing)
return 0;
/* Below are "no merge" cases, which require that the index be
* up-to-date to avoid the files getting overwritten with
* conflict resolution files.
*/
if (index) {
verify_uptodate(index);
}
nontrivial_merge = 1;
/* #2, #3, #4, #6, #7, #9, #11. */
count = 0;
if (!head_match || !remote_match) {
for (i = 1; i < head_idx; i++) {
if (stages[i]) {
keep_entry(stages[i]);
count++;
break;
}
}
}
#if DBRT_DEBUG
else {
fprintf(stderr, "read-tree: warning #16 detected\n");
show_stage_entry(stderr, "head ", stages[head_match]);
show_stage_entry(stderr, "remote ", stages[remote_match]);
}
#endif
if (head) { count += keep_entry(head); }
if (remote) { count += keep_entry(remote); }
return count;
}
/*
* Two-way merge.
*
* The rule is to "carry forward" what is in the index without losing
* information across a "fast forward", favoring a successful merge
* over a merge failure when it makes sense. For details of the
* "carry forward" rule, please see <Documentation/git-read-tree.txt>.
*
*/
static int twoway_merge(struct cache_entry **src)
{
struct cache_entry *current = src[0];
struct cache_entry *oldtree = src[1], *newtree = src[2];
if (merge_size != 2)
return error("Cannot do a twoway merge of %d trees\n",
merge_size);
if (current) {
if ((!oldtree && !newtree) || /* 4 and 5 */
(!oldtree && newtree &&
same(current, newtree)) || /* 6 and 7 */
(oldtree && newtree &&
same(oldtree, newtree)) || /* 14 and 15 */
(oldtree && newtree &&
!same(oldtree, newtree) && /* 18 and 19*/
same(current, newtree))) {
return keep_entry(current);
}
else if (oldtree && !newtree && same(current, oldtree)) {
/* 10 or 11 */
return deleted_entry(oldtree, current);
}
else if (oldtree && newtree &&
same(current, oldtree) && !same(current, newtree)) {
/* 20 or 21 */
return merged_entry(newtree, current);
}
else {
/* all other failures */
if (oldtree)
reject_merge(oldtree);
if (current)
reject_merge(current);
if (newtree)
reject_merge(newtree);
return -1;
}
}
else if (newtree)
return merged_entry(newtree, current);
else
return deleted_entry(oldtree, current);
}
/*
* One-way merge.
*
* The rule is:
* - take the stat information from stage0, take the data from stage1
*/
static int oneway_merge(struct cache_entry **src)
{
struct cache_entry *old = src[0];
struct cache_entry *a = src[1];
if (merge_size != 1)
return error("Cannot do a oneway merge of %d trees\n",
merge_size);
if (!a)
return 0;
if (old && same(old, a)) {
return keep_entry(old);
}
return merged_entry(a, NULL);
}
static int read_cache_unmerged(void)
{
int i, deleted;
struct cache_entry **dst;
read_cache();
dst = active_cache;
deleted = 0;
for (i = 0; i < active_nr; i++) {
struct cache_entry *ce = active_cache[i];
if (ce_stage(ce)) {
deleted++;
continue;
}
if (deleted)
*dst = ce;
dst++;
}
active_nr -= deleted;
return deleted;
}
static const char read_tree_usage[] = "git-read-tree (<sha> | -m [-u | -i] <sha1> [<sha2> [<sha3>]])";
static struct cache_file cache_file;
int main(int argc, char **argv)
{
int i, newfd, reset, stage = 0;
unsigned char sha1[20];
merge_fn_t fn = NULL;
newfd = hold_index_file_for_update(&cache_file, get_index_file());
if (newfd < 0)
die("unable to create new cachefile");
merge = 0;
reset = 0;
for (i = 1; i < argc; i++) {
const char *arg = argv[i];
/* "-u" means "update", meaning that a merge will update
* the working tree.
*/
if (!strcmp(arg, "-u")) {
update = 1;
continue;
}
/* "-i" means "index only", meaning that a merge will
* not even look at the working tree.
*/
if (!strcmp(arg, "-i")) {
index_only = 1;
continue;
}
/* This differs from "-m" in that we'll silently ignore unmerged entries */
if (!strcmp(arg, "--reset")) {
if (stage || merge)
usage(read_tree_usage);
reset = 1;
merge = 1;
stage = 1;
read_cache_unmerged();
continue;
}
if (!strcmp(arg, "--trivial")) {
trivial_merges_only = 1;
continue;
}
/* "-m" stands for "merge", meaning we start in stage 1 */
if (!strcmp(arg, "-m")) {
if (stage || merge)
usage(read_tree_usage);
if (read_cache_unmerged())
die("you need to resolve your current index first");
stage = 1;
merge = 1;
continue;
}
/* using -u and -i at the same time makes no sense */
if (1 < index_only + update)
usage(read_tree_usage);
if (get_sha1(arg, sha1) < 0)
usage(read_tree_usage);
if (list_tree(sha1) < 0)
die("failed to unpack tree object %s", arg);
stage++;
}
if ((update||index_only) && !merge)
usage(read_tree_usage);
if (merge) {
if (stage < 2)
die("just how do you expect me to merge %d trees?", stage-1);
switch (stage - 1) {
case 1:
fn = oneway_merge;
break;
case 2:
fn = twoway_merge;
break;
case 3:
fn = threeway_merge;
break;
default:
fn = threeway_merge;
break;
}
if (stage - 1 >= 3)
head_idx = stage - 2;
else
head_idx = 1;
}
unpack_trees(fn);
if (write_cache(newfd, active_cache, active_nr) ||
commit_index_file(&cache_file))
die("unable to write new index file");
return 0;
}