git-commit-vandalism/diff-lib.c
Junio C Hamano 730f72840c unpack-trees.c: look ahead in the index
This makes the traversal of index be in sync with the tree traversal.
When unpack_callback() is fed a set of tree entries from trees, it
inspects the name of the entry and checks if the an index entry with
the same name could be hiding behind the current index entry, and

 (1) if the name appears in the index as a leaf node, it is also
     fed to the n_way_merge() callback function;

 (2) if the name is a directory in the index, i.e. there are entries in
     that are underneath it, then nothing is fed to the n_way_merge()
     callback function;

 (3) otherwise, if the name comes before the first eligible entry in the
     index, the index entry is first unpacked alone.

When traverse_trees_recursive() descends into a subdirectory, the
cache_bottom pointer is moved to walk index entries within that directory.

All of these are omitted for diff-index, which does not even want to be
fed an index entry and a tree entry with D/F conflicts.

This fixes 3-way read-tree and exposes a bug in other parts of the system
in t6035, test #5.  The test prepares these three trees:

 O = HEAD^
    100644 blob e69de29bb2    a/b-2/c/d
    100644 blob e69de29bb2    a/b/c/d
    100644 blob e69de29bb2    a/x

 A = HEAD
    100644 blob e69de29bb2    a/b-2/c/d
    100644 blob e69de29bb2    a/b/c/d
    100644 blob 587be6b4c3f93f93c489c0111bba5596147a26cb    a/x

 B = master
    120000 blob a36b77384451ea1de7bd340ffca868249626bc52    a/b
    100644 blob e69de29bb2    a/b-2/c/d
    100644 blob e69de29bb2    a/x

With a clean index that matches HEAD, running

    git read-tree -m -u --aggressive $O $A $B

now yields

    120000 a36b77384451ea1de7bd340ffca868249626bc52 3       a/b
    100644 e69de29bb2 0       a/b-2/c/d
    100644 e69de29bb2 1       a/b/c/d
    100644 e69de29bb2 2       a/b/c/d
    100644 587be6b4c3f93f93c489c0111bba5596147a26cb 0       a/x

which is correct.  "master" created "a/b" symlink that did not exist,
and removed "a/b/c/d" while HEAD did not do touch either path.

Before this series, read-tree did not notice the situation and resolved
addition of "a/b" and removal of "a/b/c/d" independently.  If A = HEAD had
another path "a/b/c/e" added, this merge should conflict but instead it
silently resolved "a/b" and then immediately overwrote it to add
"a/b/c/e", which was quite bogus.

Tests in t1012 start to work with this.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-01-07 15:00:14 -08:00

501 lines
12 KiB
C

/*
* Copyright (C) 2005 Junio C Hamano
*/
#include "cache.h"
#include "quote.h"
#include "commit.h"
#include "diff.h"
#include "diffcore.h"
#include "revision.h"
#include "cache-tree.h"
#include "unpack-trees.h"
#include "refs.h"
/*
* diff-files
*/
/*
* Has the work tree entity been removed?
*
* Return 1 if it was removed from the work tree, 0 if an entity to be
* compared with the cache entry ce still exists (the latter includes
* the case where a directory that is not a submodule repository
* exists for ce that is a submodule -- it is a submodule that is not
* checked out). Return negative for an error.
*/
static int check_removed(const struct cache_entry *ce, struct stat *st)
{
if (lstat(ce->name, st) < 0) {
if (errno != ENOENT && errno != ENOTDIR)
return -1;
return 1;
}
if (has_symlink_leading_path(ce->name, ce_namelen(ce)))
return 1;
if (S_ISDIR(st->st_mode)) {
unsigned char sub[20];
/*
* If ce is already a gitlink, we can have a plain
* directory (i.e. the submodule is not checked out),
* or a checked out submodule. Either case this is not
* a case where something was removed from the work tree,
* so we will return 0.
*
* Otherwise, if the directory is not a submodule
* repository, that means ce which was a blob turned into
* a directory --- the blob was removed!
*/
if (!S_ISGITLINK(ce->ce_mode) &&
resolve_gitlink_ref(ce->name, "HEAD", sub))
return 1;
}
return 0;
}
int run_diff_files(struct rev_info *revs, unsigned int option)
{
int entries, i;
int diff_unmerged_stage = revs->max_count;
int silent_on_removed = option & DIFF_SILENT_ON_REMOVED;
unsigned ce_option = ((option & DIFF_RACY_IS_MODIFIED)
? CE_MATCH_RACY_IS_DIRTY : 0);
diff_set_mnemonic_prefix(&revs->diffopt, "i/", "w/");
if (diff_unmerged_stage < 0)
diff_unmerged_stage = 2;
entries = active_nr;
for (i = 0; i < entries; i++) {
struct stat st;
unsigned int oldmode, newmode;
struct cache_entry *ce = active_cache[i];
int changed;
if (DIFF_OPT_TST(&revs->diffopt, QUIET) &&
DIFF_OPT_TST(&revs->diffopt, HAS_CHANGES))
break;
if (!ce_path_match(ce, revs->prune_data))
continue;
if (ce_stage(ce)) {
struct combine_diff_path *dpath;
int num_compare_stages = 0;
size_t path_len;
path_len = ce_namelen(ce);
dpath = xmalloc(combine_diff_path_size(5, path_len));
dpath->path = (char *) &(dpath->parent[5]);
dpath->next = NULL;
dpath->len = path_len;
memcpy(dpath->path, ce->name, path_len);
dpath->path[path_len] = '\0';
hashclr(dpath->sha1);
memset(&(dpath->parent[0]), 0,
sizeof(struct combine_diff_parent)*5);
changed = check_removed(ce, &st);
if (!changed)
dpath->mode = ce_mode_from_stat(ce, st.st_mode);
else {
if (changed < 0) {
perror(ce->name);
continue;
}
if (silent_on_removed)
continue;
}
while (i < entries) {
struct cache_entry *nce = active_cache[i];
int stage;
if (strcmp(ce->name, nce->name))
break;
/* Stage #2 (ours) is the first parent,
* stage #3 (theirs) is the second.
*/
stage = ce_stage(nce);
if (2 <= stage) {
int mode = nce->ce_mode;
num_compare_stages++;
hashcpy(dpath->parent[stage-2].sha1, nce->sha1);
dpath->parent[stage-2].mode = ce_mode_from_stat(nce, mode);
dpath->parent[stage-2].status =
DIFF_STATUS_MODIFIED;
}
/* diff against the proper unmerged stage */
if (stage == diff_unmerged_stage)
ce = nce;
i++;
}
/*
* Compensate for loop update
*/
i--;
if (revs->combine_merges && num_compare_stages == 2) {
show_combined_diff(dpath, 2,
revs->dense_combined_merges,
revs);
free(dpath);
continue;
}
free(dpath);
dpath = NULL;
/*
* Show the diff for the 'ce' if we found the one
* from the desired stage.
*/
diff_unmerge(&revs->diffopt, ce->name, 0, null_sha1);
if (ce_stage(ce) != diff_unmerged_stage)
continue;
}
if (ce_uptodate(ce))
continue;
/* If CE_VALID is set, don't look at workdir for file removal */
changed = (ce->ce_flags & CE_VALID) ? 0 : check_removed(ce, &st);
if (changed) {
if (changed < 0) {
perror(ce->name);
continue;
}
if (silent_on_removed)
continue;
diff_addremove(&revs->diffopt, '-', ce->ce_mode,
ce->sha1, ce->name);
continue;
}
changed = ce_match_stat(ce, &st, ce_option);
if (!changed) {
ce_mark_uptodate(ce);
if (!DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
continue;
}
oldmode = ce->ce_mode;
newmode = ce_mode_from_stat(ce, st.st_mode);
diff_change(&revs->diffopt, oldmode, newmode,
ce->sha1, (changed ? null_sha1 : ce->sha1),
ce->name);
}
diffcore_std(&revs->diffopt);
diff_flush(&revs->diffopt);
return 0;
}
/*
* diff-index
*/
/* A file entry went away or appeared */
static void diff_index_show_file(struct rev_info *revs,
const char *prefix,
struct cache_entry *ce,
const unsigned char *sha1, unsigned int mode)
{
diff_addremove(&revs->diffopt, prefix[0], mode,
sha1, ce->name);
}
static int get_stat_data(struct cache_entry *ce,
const unsigned char **sha1p,
unsigned int *modep,
int cached, int match_missing)
{
const unsigned char *sha1 = ce->sha1;
unsigned int mode = ce->ce_mode;
if (!cached && !ce_uptodate(ce)) {
int changed;
struct stat st;
changed = check_removed(ce, &st);
if (changed < 0)
return -1;
else if (changed) {
if (match_missing) {
*sha1p = sha1;
*modep = mode;
return 0;
}
return -1;
}
changed = ce_match_stat(ce, &st, 0);
if (changed) {
mode = ce_mode_from_stat(ce, st.st_mode);
sha1 = null_sha1;
}
}
*sha1p = sha1;
*modep = mode;
return 0;
}
static void show_new_file(struct rev_info *revs,
struct cache_entry *new,
int cached, int match_missing)
{
const unsigned char *sha1;
unsigned int mode;
/*
* New file in the index: it might actually be different in
* the working copy.
*/
if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0)
return;
diff_index_show_file(revs, "+", new, sha1, mode);
}
static int show_modified(struct rev_info *revs,
struct cache_entry *old,
struct cache_entry *new,
int report_missing,
int cached, int match_missing)
{
unsigned int mode, oldmode;
const unsigned char *sha1;
if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0) {
if (report_missing)
diff_index_show_file(revs, "-", old,
old->sha1, old->ce_mode);
return -1;
}
if (revs->combine_merges && !cached &&
(hashcmp(sha1, old->sha1) || hashcmp(old->sha1, new->sha1))) {
struct combine_diff_path *p;
int pathlen = ce_namelen(new);
p = xmalloc(combine_diff_path_size(2, pathlen));
p->path = (char *) &p->parent[2];
p->next = NULL;
p->len = pathlen;
memcpy(p->path, new->name, pathlen);
p->path[pathlen] = 0;
p->mode = mode;
hashclr(p->sha1);
memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
p->parent[0].status = DIFF_STATUS_MODIFIED;
p->parent[0].mode = new->ce_mode;
hashcpy(p->parent[0].sha1, new->sha1);
p->parent[1].status = DIFF_STATUS_MODIFIED;
p->parent[1].mode = old->ce_mode;
hashcpy(p->parent[1].sha1, old->sha1);
show_combined_diff(p, 2, revs->dense_combined_merges, revs);
free(p);
return 0;
}
oldmode = old->ce_mode;
if (mode == oldmode && !hashcmp(sha1, old->sha1) &&
!DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
return 0;
diff_change(&revs->diffopt, oldmode, mode,
old->sha1, sha1, old->name);
return 0;
}
/*
* This gets a mix of an existing index and a tree, one pathname entry
* at a time. The index entry may be a single stage-0 one, but it could
* also be multiple unmerged entries (in which case idx_pos/idx_nr will
* give you the position and number of entries in the index).
*/
static void do_oneway_diff(struct unpack_trees_options *o,
struct cache_entry *idx,
struct cache_entry *tree)
{
struct rev_info *revs = o->unpack_data;
int match_missing, cached;
/* if the entry is not checked out, don't examine work tree */
cached = o->index_only || (idx && (idx->ce_flags & CE_VALID));
/*
* Backward compatibility wart - "diff-index -m" does
* not mean "do not ignore merges", but "match_missing".
*
* But with the revision flag parsing, that's found in
* "!revs->ignore_merges".
*/
match_missing = !revs->ignore_merges;
if (cached && idx && ce_stage(idx)) {
diff_unmerge(&revs->diffopt, idx->name, idx->ce_mode,
idx->sha1);
return;
}
/*
* Something added to the tree?
*/
if (!tree) {
show_new_file(revs, idx, cached, match_missing);
return;
}
/*
* Something removed from the tree?
*/
if (!idx) {
diff_index_show_file(revs, "-", tree, tree->sha1, tree->ce_mode);
return;
}
/* Show difference between old and new */
show_modified(revs, tree, idx, 1, cached, match_missing);
}
/*
* The unpack_trees() interface is designed for merging, so
* the different source entries are designed primarily for
* the source trees, with the old index being really mainly
* used for being replaced by the result.
*
* For diffing, the index is more important, and we only have a
* single tree.
*
* We're supposed to advance o->pos to skip what we have already processed.
*
* This wrapper makes it all more readable, and takes care of all
* the fairly complex unpack_trees() semantic requirements, including
* the skipping, the path matching, the type conflict cases etc.
*/
static int oneway_diff(struct cache_entry **src, struct unpack_trees_options *o)
{
struct cache_entry *idx = src[0];
struct cache_entry *tree = src[1];
struct rev_info *revs = o->unpack_data;
/*
* Unpack-trees generates a DF/conflict entry if
* there was a directory in the index and a tree
* in the tree. From a diff standpoint, that's a
* delete of the tree and a create of the file.
*/
if (tree == o->df_conflict_entry)
tree = NULL;
if (ce_path_match(idx ? idx : tree, revs->prune_data))
do_oneway_diff(o, idx, tree);
return 0;
}
int run_diff_index(struct rev_info *revs, int cached)
{
struct object *ent;
struct tree *tree;
const char *tree_name;
struct unpack_trees_options opts;
struct tree_desc t;
ent = revs->pending.objects[0].item;
tree_name = revs->pending.objects[0].name;
tree = parse_tree_indirect(ent->sha1);
if (!tree)
return error("bad tree object %s", tree_name);
memset(&opts, 0, sizeof(opts));
opts.head_idx = 1;
opts.index_only = cached;
opts.diff_index_cached = (cached &&
!DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER));
opts.merge = 1;
opts.fn = oneway_diff;
opts.unpack_data = revs;
opts.src_index = &the_index;
opts.dst_index = NULL;
init_tree_desc(&t, tree->buffer, tree->size);
if (unpack_trees(1, &t, &opts))
exit(128);
diff_set_mnemonic_prefix(&revs->diffopt, "c/", cached ? "i/" : "w/");
diffcore_fix_diff_index(&revs->diffopt);
diffcore_std(&revs->diffopt);
diff_flush(&revs->diffopt);
return 0;
}
int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt)
{
struct tree *tree;
struct rev_info revs;
int i;
struct cache_entry **dst;
struct cache_entry *last = NULL;
struct unpack_trees_options opts;
struct tree_desc t;
/*
* This is used by git-blame to run diff-cache internally;
* it potentially needs to repeatedly run this, so we will
* start by removing the higher order entries the last round
* left behind.
*/
dst = active_cache;
for (i = 0; i < active_nr; i++) {
struct cache_entry *ce = active_cache[i];
if (ce_stage(ce)) {
if (last && !strcmp(ce->name, last->name))
continue;
cache_tree_invalidate_path(active_cache_tree,
ce->name);
last = ce;
ce->ce_flags |= CE_REMOVE;
}
*dst++ = ce;
}
active_nr = dst - active_cache;
init_revisions(&revs, NULL);
revs.prune_data = opt->paths;
tree = parse_tree_indirect(tree_sha1);
if (!tree)
die("bad tree object %s", sha1_to_hex(tree_sha1));
memset(&opts, 0, sizeof(opts));
opts.head_idx = 1;
opts.index_only = 1;
opts.diff_index_cached = !DIFF_OPT_TST(opt, FIND_COPIES_HARDER);
opts.merge = 1;
opts.fn = oneway_diff;
opts.unpack_data = &revs;
opts.src_index = &the_index;
opts.dst_index = &the_index;
init_tree_desc(&t, tree->buffer, tree->size);
if (unpack_trees(1, &t, &opts))
exit(128);
return 0;
}
int index_differs_from(const char *def, int diff_flags)
{
struct rev_info rev;
init_revisions(&rev, NULL);
setup_revisions(0, NULL, &rev, def);
DIFF_OPT_SET(&rev.diffopt, QUIET);
DIFF_OPT_SET(&rev.diffopt, EXIT_WITH_STATUS);
rev.diffopt.flags |= diff_flags;
run_diff_index(&rev, 1);
if (rev.pending.alloc)
free(rev.pending.objects);
return (DIFF_OPT_TST(&rev.diffopt, HAS_CHANGES) != 0);
}