Revision 1335d76e4569fa84e52dc24c88c04daeae6e160e authored by Junio C Hamano on 08 July 2016, 17:59:15 UTC, committed by Junio C Hamano on 12 July 2016, 20:06:43 UTC
When merge_recursive() decides what the correct blob object merge result for a path should be, it uses update_file_flags() helper function to write it out to a working tree file and then calls add_cacheinfo(). The add_cacheinfo() function in turn calls make_cache_entry() to create a new cache entry to replace the higher-stage entries for the path that represents the conflict. The make_cache_entry() function calls refresh_cache_entry() to fill in the cached stat information. To mark a cache entry as up-to-date, the data is re-read from the file in the working tree, and goes through convert_to_git() conversion to be compared with the blob object name the new cache entry records. It is important to note that this happens while the higher-stage entries, which are going to be replaced with the new entry, are still in the index. Unfortunately, the convert_to_git() conversion has a misguided "safer crlf" mechanism baked in, and looks at the existing cache entry for the path to decide how to convert the contents in the working tree file. If our side (i.e. stage#2) records a text blob with CRLF in it, even when the system is configured to record LF in blobs and convert them to CRLF upon checkout (and back to LF upon checkin), the "safer crlf" mechanism stops us doing so. This especially poses a problem during a renormalizing merge, where the merge result for the path is computed by first "normalizing" the blobs involved in the merge by using convert_to_working_tree() followed by convert_to_git() with "safer crlf" disabled. The merge result that is computed correctly and fed to add_cacheinfo() via update_file_flags() does _not_ match what refresh_cache_entry() sees by converting the working tree file via convert_to_git(). We can work this around by not refreshing the new cache entry in make_cache_entry() called by add_cacheinfo(). After add_cacheinfo() adds the new entry, we can call refresh_cache_entry() on that, knowing that addition of this new cache entry would have removed the stale cache entries that had CRLF in stage #2 that were carried over before the renormalizing merge started and will not interfere with the correct recording of the result. The test update was taken from a series by Torsten Bögershausen that attempted to fix this with a different approach. Signed-off-by: Torsten Bögershausen <tboegi@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com> Reviewed-by: Torsten Bögershausen <tboegi@web.de>
1 parent 6523728
split-index.c
#include "cache.h"
#include "split-index.h"
#include "ewah/ewok.h"
struct split_index *init_split_index(struct index_state *istate)
{
if (!istate->split_index) {
istate->split_index = xcalloc(1, sizeof(*istate->split_index));
istate->split_index->refcount = 1;
}
return istate->split_index;
}
int read_link_extension(struct index_state *istate,
const void *data_, unsigned long sz)
{
const unsigned char *data = data_;
struct split_index *si;
int ret;
if (sz < 20)
return error("corrupt link extension (too short)");
si = init_split_index(istate);
hashcpy(si->base_sha1, data);
data += 20;
sz -= 20;
if (!sz)
return 0;
si->delete_bitmap = ewah_new();
ret = ewah_read_mmap(si->delete_bitmap, data, sz);
if (ret < 0)
return error("corrupt delete bitmap in link extension");
data += ret;
sz -= ret;
si->replace_bitmap = ewah_new();
ret = ewah_read_mmap(si->replace_bitmap, data, sz);
if (ret < 0)
return error("corrupt replace bitmap in link extension");
if (ret != sz)
return error("garbage at the end of link extension");
return 0;
}
int write_link_extension(struct strbuf *sb,
struct index_state *istate)
{
struct split_index *si = istate->split_index;
strbuf_add(sb, si->base_sha1, 20);
if (!si->delete_bitmap && !si->replace_bitmap)
return 0;
ewah_serialize_strbuf(si->delete_bitmap, sb);
ewah_serialize_strbuf(si->replace_bitmap, sb);
return 0;
}
static void mark_base_index_entries(struct index_state *base)
{
int i;
/*
* To keep track of the shared entries between
* istate->base->cache[] and istate->cache[], base entry
* position is stored in each base entry. All positions start
* from 1 instead of 0, which is resrved to say "this is a new
* entry".
*/
for (i = 0; i < base->cache_nr; i++)
base->cache[i]->index = i + 1;
}
void move_cache_to_base_index(struct index_state *istate)
{
struct split_index *si = istate->split_index;
int i;
/*
* do not delete old si->base, its index entries may be shared
* with istate->cache[]. Accept a bit of leaking here because
* this code is only used by short-lived update-index.
*/
si->base = xcalloc(1, sizeof(*si->base));
si->base->version = istate->version;
/* zero timestamp disables racy test in ce_write_index() */
si->base->timestamp = istate->timestamp;
ALLOC_GROW(si->base->cache, istate->cache_nr, si->base->cache_alloc);
si->base->cache_nr = istate->cache_nr;
memcpy(si->base->cache, istate->cache,
sizeof(*istate->cache) * istate->cache_nr);
mark_base_index_entries(si->base);
for (i = 0; i < si->base->cache_nr; i++)
si->base->cache[i]->ce_flags &= ~CE_UPDATE_IN_BASE;
}
static void mark_entry_for_delete(size_t pos, void *data)
{
struct index_state *istate = data;
if (pos >= istate->cache_nr)
die("position for delete %d exceeds base index size %d",
(int)pos, istate->cache_nr);
istate->cache[pos]->ce_flags |= CE_REMOVE;
istate->split_index->nr_deletions = 1;
}
static void replace_entry(size_t pos, void *data)
{
struct index_state *istate = data;
struct split_index *si = istate->split_index;
struct cache_entry *dst, *src;
if (pos >= istate->cache_nr)
die("position for replacement %d exceeds base index size %d",
(int)pos, istate->cache_nr);
if (si->nr_replacements >= si->saved_cache_nr)
die("too many replacements (%d vs %d)",
si->nr_replacements, si->saved_cache_nr);
dst = istate->cache[pos];
if (dst->ce_flags & CE_REMOVE)
die("entry %d is marked as both replaced and deleted",
(int)pos);
src = si->saved_cache[si->nr_replacements];
if (ce_namelen(src))
die("corrupt link extension, entry %d should have "
"zero length name", (int)pos);
src->index = pos + 1;
src->ce_flags |= CE_UPDATE_IN_BASE;
src->ce_namelen = dst->ce_namelen;
copy_cache_entry(dst, src);
free(src);
si->nr_replacements++;
}
void merge_base_index(struct index_state *istate)
{
struct split_index *si = istate->split_index;
unsigned int i;
mark_base_index_entries(si->base);
si->saved_cache = istate->cache;
si->saved_cache_nr = istate->cache_nr;
istate->cache_nr = si->base->cache_nr;
istate->cache = NULL;
istate->cache_alloc = 0;
ALLOC_GROW(istate->cache, istate->cache_nr, istate->cache_alloc);
memcpy(istate->cache, si->base->cache,
sizeof(*istate->cache) * istate->cache_nr);
si->nr_deletions = 0;
si->nr_replacements = 0;
ewah_each_bit(si->replace_bitmap, replace_entry, istate);
ewah_each_bit(si->delete_bitmap, mark_entry_for_delete, istate);
if (si->nr_deletions)
remove_marked_cache_entries(istate);
for (i = si->nr_replacements; i < si->saved_cache_nr; i++) {
if (!ce_namelen(si->saved_cache[i]))
die("corrupt link extension, entry %d should "
"have non-zero length name", i);
add_index_entry(istate, si->saved_cache[i],
ADD_CACHE_OK_TO_ADD |
ADD_CACHE_KEEP_CACHE_TREE |
/*
* we may have to replay what
* merge-recursive.c:update_stages()
* does, which has this flag on
*/
ADD_CACHE_SKIP_DFCHECK);
si->saved_cache[i] = NULL;
}
ewah_free(si->delete_bitmap);
ewah_free(si->replace_bitmap);
free(si->saved_cache);
si->delete_bitmap = NULL;
si->replace_bitmap = NULL;
si->saved_cache = NULL;
si->saved_cache_nr = 0;
}
void prepare_to_write_split_index(struct index_state *istate)
{
struct split_index *si = init_split_index(istate);
struct cache_entry **entries = NULL, *ce;
int i, nr_entries = 0, nr_alloc = 0;
si->delete_bitmap = ewah_new();
si->replace_bitmap = ewah_new();
if (si->base) {
/* Go through istate->cache[] and mark CE_MATCHED to
* entry with positive index. We'll go through
* base->cache[] later to delete all entries in base
* that are not marked eith either CE_MATCHED or
* CE_UPDATE_IN_BASE. If istate->cache[i] is a
* duplicate, deduplicate it.
*/
for (i = 0; i < istate->cache_nr; i++) {
struct cache_entry *base;
/* namelen is checked separately */
const unsigned int ondisk_flags =
CE_STAGEMASK | CE_VALID | CE_EXTENDED_FLAGS;
unsigned int ce_flags, base_flags, ret;
ce = istate->cache[i];
if (!ce->index)
continue;
if (ce->index > si->base->cache_nr) {
ce->index = 0;
continue;
}
ce->ce_flags |= CE_MATCHED; /* or "shared" */
base = si->base->cache[ce->index - 1];
if (ce == base)
continue;
if (ce->ce_namelen != base->ce_namelen ||
strcmp(ce->name, base->name)) {
ce->index = 0;
continue;
}
ce_flags = ce->ce_flags;
base_flags = base->ce_flags;
/* only on-disk flags matter */
ce->ce_flags &= ondisk_flags;
base->ce_flags &= ondisk_flags;
ret = memcmp(&ce->ce_stat_data, &base->ce_stat_data,
offsetof(struct cache_entry, name) -
offsetof(struct cache_entry, ce_stat_data));
ce->ce_flags = ce_flags;
base->ce_flags = base_flags;
if (ret)
ce->ce_flags |= CE_UPDATE_IN_BASE;
free(base);
si->base->cache[ce->index - 1] = ce;
}
for (i = 0; i < si->base->cache_nr; i++) {
ce = si->base->cache[i];
if ((ce->ce_flags & CE_REMOVE) ||
!(ce->ce_flags & CE_MATCHED))
ewah_set(si->delete_bitmap, i);
else if (ce->ce_flags & CE_UPDATE_IN_BASE) {
ewah_set(si->replace_bitmap, i);
ce->ce_flags |= CE_STRIP_NAME;
ALLOC_GROW(entries, nr_entries+1, nr_alloc);
entries[nr_entries++] = ce;
}
}
}
for (i = 0; i < istate->cache_nr; i++) {
ce = istate->cache[i];
if ((!si->base || !ce->index) && !(ce->ce_flags & CE_REMOVE)) {
assert(!(ce->ce_flags & CE_STRIP_NAME));
ALLOC_GROW(entries, nr_entries+1, nr_alloc);
entries[nr_entries++] = ce;
}
ce->ce_flags &= ~CE_MATCHED;
}
/*
* take cache[] out temporarily, put entries[] in its place
* for writing
*/
si->saved_cache = istate->cache;
si->saved_cache_nr = istate->cache_nr;
istate->cache = entries;
istate->cache_nr = nr_entries;
}
void finish_writing_split_index(struct index_state *istate)
{
struct split_index *si = init_split_index(istate);
ewah_free(si->delete_bitmap);
ewah_free(si->replace_bitmap);
si->delete_bitmap = NULL;
si->replace_bitmap = NULL;
free(istate->cache);
istate->cache = si->saved_cache;
istate->cache_nr = si->saved_cache_nr;
}
void discard_split_index(struct index_state *istate)
{
struct split_index *si = istate->split_index;
if (!si)
return;
istate->split_index = NULL;
si->refcount--;
if (si->refcount)
return;
if (si->base) {
discard_index(si->base);
free(si->base);
}
free(si);
}
void save_or_free_index_entry(struct index_state *istate, struct cache_entry *ce)
{
if (ce->index &&
istate->split_index &&
istate->split_index->base &&
ce->index <= istate->split_index->base->cache_nr &&
ce == istate->split_index->base->cache[ce->index - 1])
ce->ce_flags |= CE_REMOVE;
else
free(ce);
}
void replace_index_entry_in_base(struct index_state *istate,
struct cache_entry *old,
struct cache_entry *new)
{
if (old->index &&
istate->split_index &&
istate->split_index->base &&
old->index <= istate->split_index->base->cache_nr) {
new->index = old->index;
if (old != istate->split_index->base->cache[new->index - 1])
free(istate->split_index->base->cache[new->index - 1]);
istate->split_index->base->cache[new->index - 1] = new;
}
}
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