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racy: make git_index_read_index handle raciness

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Ensure that `git_index_read_index` clears the uptodate bit on
files that it modifies.

Further, do not propagate the cache from an on-disk index into
another on-disk index.  Although this should not be done, as
`git_index_read_index` is used to bring an in-memory index into
another index (that may or may not be on-disk), ensure that we do
not accidentally bring in these bits when misused.
This commit is contained in:
Edward Thomson 2015-11-16 18:06:52 -05:00 committed by Edward Thomson
parent c30051f0d0
commit 5f32c50683
2 changed files with 98 additions and 32 deletions
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82
src/index.c
View File

@ -1003,20 +1003,11 @@ static int index_entry_reuc_init(git_index_reuc_entry **reuc_out,
static void index_entry_cpy(
git_index_entry *tgt,
git_index *index,
const git_index_entry *src,
bool update_path)
const git_index_entry *src)
{
const char *tgt_path = tgt->path;
memcpy(tgt, src, sizeof(*tgt));
/* keep the existing path buffer, but update the path to the one
* given by the caller, if we trust it.
*/
tgt->path = tgt_path;
if (index->ignore_case && update_path)
memcpy((char *)tgt->path, src->path, strlen(tgt->path));
}
static int index_entry_dup(
@ -1024,18 +1015,32 @@ static int index_entry_dup(
git_index *index,
const git_index_entry *src)
{
git_index_entry *entry;
if (!src) {
*out = NULL;
return 0;
}
if (index_entry_create(&entry, INDEX_OWNER(index), src->path) < 0)
if (index_entry_create(out, INDEX_OWNER(index), src->path) < 0)
return -1;
index_entry_cpy(entry, index, src, false);
*out = entry;
index_entry_cpy(*out, src);
return 0;
}
static void index_entry_cpy_nocache(
git_index_entry *tgt,
const git_index_entry *src)
{
git_oid_cpy(&tgt->id, &src->id);
tgt->mode = src->mode;
tgt->flags = src->flags;
tgt->flags_extended = (src->flags_extended & GIT_IDXENTRY_EXTENDED_FLAGS);
}
static int index_entry_dup_nocache(
git_index_entry **out,
git_index *index,
const git_index_entry *src)
{
if (index_entry_create(out, INDEX_OWNER(index), src->path) < 0)
return -1;
index_entry_cpy_nocache(*out, src);
return 0;
}
@ -1331,8 +1336,13 @@ static int index_insert(
* and return it in place of the passed in one.
*/
else if (existing) {
if (replace)
index_entry_cpy(existing, index, entry, trust_path);
if (replace) {
index_entry_cpy(existing, entry);
if (trust_path)
memcpy((char *)existing->path, entry->path, strlen(entry->path));
}
index_entry_free(entry);
*entry_ptr = entry = existing;
}
@ -1709,9 +1719,12 @@ int git_index_conflict_add(git_index *index,
assert (index);
if ((ret = index_entry_dup(&entries[0], index, ancestor_entry)) < 0 ||
(ret = index_entry_dup(&entries[1], index, our_entry)) < 0 ||
(ret = index_entry_dup(&entries[2], index, their_entry)) < 0)
if ((ancestor_entry &&
(ret = index_entry_dup(&entries[0], index, ancestor_entry)) < 0) ||
(our_entry &&
(ret = index_entry_dup(&entries[1], index, our_entry)) < 0) ||
(their_entry &&
(ret = index_entry_dup(&entries[2], index, their_entry)) < 0))
goto on_error;
/* Validate entries */
@ -2849,7 +2862,7 @@ static int read_tree_cb(
entry->mode == old_entry->mode &&
git_oid_equal(&entry->id, &old_entry->id))
{
index_entry_cpy(entry, data->index, old_entry, false);
index_entry_cpy(entry, old_entry);
entry->flags_extended = 0;
}
@ -2974,7 +2987,10 @@ int git_index_read_index(
goto done;
while (true) {
git_index_entry *add_entry = NULL, *remove_entry = NULL;
git_index_entry
*dup_entry = NULL,
*add_entry = NULL,
*remove_entry = NULL;
int diff;
if (old_entry && new_entry)
@ -2989,8 +3005,7 @@ int git_index_read_index(
if (diff < 0) {
remove_entry = (git_index_entry *)old_entry;
} else if (diff > 0) {
if ((error = index_entry_dup(&add_entry, index, new_entry)) < 0)
goto done;
dup_entry = (git_index_entry *)new_entry;
} else {
/* Path and stage are equal, if the OID is equal, keep it to
* keep the stat cache data.
@ -2998,13 +3013,16 @@ int git_index_read_index(
if (git_oid_equal(&old_entry->id, &new_entry->id)) {
add_entry = (git_index_entry *)old_entry;
} else {
if ((error = index_entry_dup(&add_entry, index, new_entry)) < 0)
goto done;
dup_entry = (git_index_entry *)new_entry;
remove_entry = (git_index_entry *)old_entry;
}
}
if (dup_entry) {
if ((error = index_entry_dup_nocache(&add_entry, index, dup_entry)) < 0)
goto done;
}
if (add_entry) {
if ((error = git_vector_insert(&new_entries, add_entry)) == 0)
INSERT_IN_MAP_EX(index, new_entries_map, add_entry, error);

48
tests/index/racy.c
View File

@ -278,3 +278,51 @@ void test_index_racy__read_tree_clears_uptodate_bit(void)
git_tree_free(tree);
git_index_free(index);
}
void test_index_racy__read_index_smudges(void)
{
git_index *index, *newindex;
const git_index_entry *entry;
/* if we are reading an index into our new index, ensure that any
* racy entries in the index that we're reading are smudged so that
* we don't propagate their timestamps without further investigation.
*/
setup_race();
cl_git_pass(git_repository_index(&index, g_repo));
cl_git_pass(git_index_new(&newindex));
cl_git_pass(git_index_read_index(newindex, index));
cl_assert(entry = git_index_get_bypath(newindex, "A", 0));
cl_assert_equal_i(0, entry->file_size);
git_index_free(index);
git_index_free(newindex);
}
void test_index_racy__read_index_clears_uptodate_bit(void)
{
git_index *index, *newindex;
const git_index_entry *entry;
git_oid id;
setup_uptodate_files();
cl_git_pass(git_repository_index(&index, g_repo));
cl_git_pass(git_index_new(&newindex));
cl_git_pass(git_index_read_index(newindex, index));
/* ensure that files brought in from the other index are not uptodate */
cl_assert((entry = git_index_get_bypath(newindex, "A", 0)));
cl_assert_equal_i(0, (entry->flags_extended & GIT_IDXENTRY_UPTODATE));
cl_assert((entry = git_index_get_bypath(newindex, "B", 0)));
cl_assert_equal_i(0, (entry->flags_extended & GIT_IDXENTRY_UPTODATE));
cl_assert((entry = git_index_get_bypath(newindex, "C", 0)));
cl_assert_equal_i(0, (entry->flags_extended & GIT_IDXENTRY_UPTODATE));
git_index_free(index);
git_index_free(newindex);
}