git/sparse-index.c
Jeff King 1ee7a5c388 read_tree(): respect max_allowed_tree_depth
The read_tree() function reads trees recursively (via its read_tree_at()
helper). This can cause it to run out of stack space on very deep trees.
Let's teach it about the new core.maxTreeDepth option.

The easiest way to demonstrate this is via "ls-tree -r", which the test
covers. Note that I needed a tree depth of ~30k to trigger a segfault on
my Linux system, not the 4100 used by our "big" test in t6700. However,
that test still tells us what we want: that the default 4096 limit is
enough to prevent segfaults on all platforms. We could bump it, but that
increases the cost of the test setup for little gain.

As an interesting side-note: when I originally wrote this patch about 4
years ago, I needed a depth of ~50k to segfault. But porting it forward,
the number is much lower. Seemingly little things like cf0983213c (hash:
add an algo member to struct object_id, 2021-04-26) take it from 32,722
to 29,080.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-08-31 15:51:08 -07:00

603 lines
15 KiB
C

#include "git-compat-util.h"
#include "environment.h"
#include "gettext.h"
#include "name-hash.h"
#include "read-cache-ll.h"
#include "repository.h"
#include "sparse-index.h"
#include "tree.h"
#include "pathspec.h"
#include "trace2.h"
#include "cache-tree.h"
#include "config.h"
#include "dir.h"
#include "fsmonitor-ll.h"
struct modify_index_context {
struct index_state *write;
struct pattern_list *pl;
};
static struct cache_entry *construct_sparse_dir_entry(
struct index_state *istate,
const char *sparse_dir,
struct cache_tree *tree)
{
struct cache_entry *de;
de = make_cache_entry(istate, S_IFDIR, &tree->oid, sparse_dir, 0, 0);
de->ce_flags |= CE_SKIP_WORKTREE;
return de;
}
/*
* Returns the number of entries "inserted" into the index.
*/
static int convert_to_sparse_rec(struct index_state *istate,
int num_converted,
int start, int end,
const char *ct_path, size_t ct_pathlen,
struct cache_tree *ct)
{
int i, can_convert = 1;
int start_converted = num_converted;
struct strbuf child_path = STRBUF_INIT;
/*
* Is the current path outside of the sparse cone?
* Then check if the region can be replaced by a sparse
* directory entry (everything is sparse and merged).
*/
if (path_in_sparse_checkout(ct_path, istate))
can_convert = 0;
for (i = start; can_convert && i < end; i++) {
struct cache_entry *ce = istate->cache[i];
if (ce_stage(ce) ||
S_ISGITLINK(ce->ce_mode) ||
!(ce->ce_flags & CE_SKIP_WORKTREE))
can_convert = 0;
}
if (can_convert) {
struct cache_entry *se;
se = construct_sparse_dir_entry(istate, ct_path, ct);
istate->cache[num_converted++] = se;
return 1;
}
for (i = start; i < end; ) {
int count, span, pos = -1;
const char *base, *slash;
struct cache_entry *ce = istate->cache[i];
/*
* Detect if this is a normal entry outside of any subtree
* entry.
*/
base = ce->name + ct_pathlen;
slash = strchr(base, '/');
if (slash)
pos = cache_tree_subtree_pos(ct, base, slash - base);
if (pos < 0) {
istate->cache[num_converted++] = ce;
i++;
continue;
}
strbuf_setlen(&child_path, 0);
strbuf_add(&child_path, ce->name, slash - ce->name + 1);
span = ct->down[pos]->cache_tree->entry_count;
count = convert_to_sparse_rec(istate,
num_converted, i, i + span,
child_path.buf, child_path.len,
ct->down[pos]->cache_tree);
num_converted += count;
i += span;
}
strbuf_release(&child_path);
return num_converted - start_converted;
}
int set_sparse_index_config(struct repository *repo, int enable)
{
int res = repo_config_set_worktree_gently(repo,
"index.sparse",
enable ? "true" : "false");
prepare_repo_settings(repo);
repo->settings.sparse_index = enable;
return res;
}
static int index_has_unmerged_entries(struct index_state *istate)
{
int i;
for (i = 0; i < istate->cache_nr; i++) {
if (ce_stage(istate->cache[i]))
return 1;
}
return 0;
}
int is_sparse_index_allowed(struct index_state *istate, int flags)
{
if (!core_apply_sparse_checkout || !core_sparse_checkout_cone)
return 0;
if (!(flags & SPARSE_INDEX_MEMORY_ONLY)) {
int test_env;
/*
* The sparse index is not (yet) integrated with a split index.
*/
if (istate->split_index || git_env_bool("GIT_TEST_SPLIT_INDEX", 0))
return 0;
/*
* The GIT_TEST_SPARSE_INDEX environment variable triggers the
* index.sparse config variable to be on.
*/
test_env = git_env_bool("GIT_TEST_SPARSE_INDEX", -1);
if (test_env >= 0)
set_sparse_index_config(istate->repo, test_env);
/*
* Only convert to sparse if index.sparse is set.
*/
prepare_repo_settings(istate->repo);
if (!istate->repo->settings.sparse_index)
return 0;
}
if (init_sparse_checkout_patterns(istate))
return 0;
/*
* We need cone-mode patterns to use sparse-index. If a user edits
* their sparse-checkout file manually, then we can detect during
* parsing that they are not actually using cone-mode patterns and
* hence we need to abort this conversion _without error_. Warnings
* already exist in the pattern parsing to inform the user of their
* bad patterns.
*/
if (!istate->sparse_checkout_patterns->use_cone_patterns)
return 0;
return 1;
}
int convert_to_sparse(struct index_state *istate, int flags)
{
/*
* If the index is already sparse, empty, or otherwise
* cannot be converted to sparse, do not convert.
*/
if (istate->sparse_index == INDEX_COLLAPSED || !istate->cache_nr ||
!is_sparse_index_allowed(istate, flags))
return 0;
/*
* NEEDSWORK: If we have unmerged entries, then stay full.
* Unmerged entries prevent the cache-tree extension from working.
*/
if (index_has_unmerged_entries(istate))
return 0;
if (!cache_tree_fully_valid(istate->cache_tree)) {
/* Clear and recompute the cache-tree */
cache_tree_free(&istate->cache_tree);
/*
* Silently return if there is a problem with the cache tree update,
* which might just be due to a conflict state in some entry.
*
* This might create new tree objects, so be sure to use
* WRITE_TREE_MISSING_OK.
*/
if (cache_tree_update(istate, WRITE_TREE_MISSING_OK))
return 0;
}
remove_fsmonitor(istate);
trace2_region_enter("index", "convert_to_sparse", istate->repo);
istate->cache_nr = convert_to_sparse_rec(istate,
0, 0, istate->cache_nr,
"", 0, istate->cache_tree);
/* Clear and recompute the cache-tree */
cache_tree_free(&istate->cache_tree);
cache_tree_update(istate, 0);
istate->fsmonitor_has_run_once = 0;
FREE_AND_NULL(istate->fsmonitor_dirty);
FREE_AND_NULL(istate->fsmonitor_last_update);
istate->sparse_index = INDEX_COLLAPSED;
trace2_region_leave("index", "convert_to_sparse", istate->repo);
return 0;
}
static void set_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
{
ALLOC_GROW(istate->cache, nr + 1, istate->cache_alloc);
istate->cache[nr] = ce;
add_name_hash(istate, ce);
}
static int add_path_to_index(const struct object_id *oid,
struct strbuf *base, const char *path,
unsigned int mode, void *context)
{
struct modify_index_context *ctx = (struct modify_index_context *)context;
struct cache_entry *ce;
size_t len = base->len;
if (S_ISDIR(mode)) {
int dtype;
size_t baselen = base->len;
if (!ctx->pl)
return READ_TREE_RECURSIVE;
/*
* Have we expanded to a point outside of the sparse-checkout?
*
* Artificially pad the path name with a slash "/" to
* indicate it as a directory, and add an arbitrary file
* name ("-") so we can consider base->buf as a file name
* to match against the cone-mode patterns.
*
* If we compared just "path", then we would expand more
* than we should. Since every file at root is always
* included, we would expand every directory at root at
* least one level deep instead of using sparse directory
* entries.
*/
strbuf_addstr(base, path);
strbuf_add(base, "/-", 2);
if (path_matches_pattern_list(base->buf, base->len,
NULL, &dtype,
ctx->pl, ctx->write)) {
strbuf_setlen(base, baselen);
return READ_TREE_RECURSIVE;
}
/*
* The path "{base}{path}/" is a sparse directory. Create the correct
* name for inserting the entry into the index.
*/
strbuf_setlen(base, base->len - 1);
} else {
strbuf_addstr(base, path);
}
ce = make_cache_entry(ctx->write, mode, oid, base->buf, 0, 0);
ce->ce_flags |= CE_SKIP_WORKTREE | CE_EXTENDED;
set_index_entry(ctx->write, ctx->write->cache_nr++, ce);
strbuf_setlen(base, len);
return 0;
}
void expand_index(struct index_state *istate, struct pattern_list *pl)
{
int i;
struct index_state *full;
struct strbuf base = STRBUF_INIT;
const char *tr_region;
struct modify_index_context ctx;
/*
* If the index is already full, then keep it full. We will convert
* it to a sparse index on write, if possible.
*/
if (istate->sparse_index == INDEX_EXPANDED)
return;
/*
* If our index is sparse, but our new pattern set does not use
* cone mode patterns, then we need to expand the index before we
* continue. A NULL pattern set indicates a full expansion to a
* full index.
*/
if (pl && !pl->use_cone_patterns) {
pl = NULL;
} else {
/*
* We might contract file entries into sparse-directory
* entries, and for that we will need the cache tree to
* be recomputed.
*/
cache_tree_free(&istate->cache_tree);
/*
* If there is a problem creating the cache tree, then we
* need to expand to a full index since we cannot satisfy
* the current request as a sparse index.
*/
if (cache_tree_update(istate, 0))
pl = NULL;
}
/*
* A NULL pattern set indicates we are expanding a full index, so
* we use a special region name that indicates the full expansion.
* This is used by test cases, but also helps to differentiate the
* two cases.
*/
tr_region = pl ? "expand_index" : "ensure_full_index";
trace2_region_enter("index", tr_region, istate->repo);
/* initialize basics of new index */
full = xcalloc(1, sizeof(struct index_state));
memcpy(full, istate, sizeof(struct index_state));
/*
* This slightly-misnamed 'full' index might still be sparse if we
* are only modifying the list of sparse directories. This hinges
* on whether we have a non-NULL pattern list.
*/
full->sparse_index = pl ? INDEX_PARTIALLY_SPARSE : INDEX_EXPANDED;
/* then change the necessary things */
full->cache_alloc = (3 * istate->cache_alloc) / 2;
full->cache_nr = 0;
ALLOC_ARRAY(full->cache, full->cache_alloc);
ctx.write = full;
ctx.pl = pl;
for (i = 0; i < istate->cache_nr; i++) {
struct cache_entry *ce = istate->cache[i];
struct tree *tree;
struct pathspec ps;
int dtype;
if (!S_ISSPARSEDIR(ce->ce_mode)) {
set_index_entry(full, full->cache_nr++, ce);
continue;
}
/* We now have a sparse directory entry. Should we expand? */
if (pl &&
path_matches_pattern_list(ce->name, ce->ce_namelen,
NULL, &dtype,
pl, istate) == NOT_MATCHED) {
set_index_entry(full, full->cache_nr++, ce);
continue;
}
if (!(ce->ce_flags & CE_SKIP_WORKTREE))
warning(_("index entry is a directory, but not sparse (%08x)"),
ce->ce_flags);
/* recursively walk into cd->name */
tree = lookup_tree(istate->repo, &ce->oid);
memset(&ps, 0, sizeof(ps));
ps.recursive = 1;
ps.has_wildcard = 1;
ps.max_depth = -1;
strbuf_setlen(&base, 0);
strbuf_add(&base, ce->name, strlen(ce->name));
read_tree_at(istate->repo, tree, &base, 0, &ps,
add_path_to_index, &ctx);
/* free directory entries. full entries are re-used */
discard_cache_entry(ce);
}
/* Copy back into original index. */
memcpy(&istate->name_hash, &full->name_hash, sizeof(full->name_hash));
memcpy(&istate->dir_hash, &full->dir_hash, sizeof(full->dir_hash));
istate->sparse_index = pl ? INDEX_PARTIALLY_SPARSE : INDEX_EXPANDED;
free(istate->cache);
istate->cache = full->cache;
istate->cache_nr = full->cache_nr;
istate->cache_alloc = full->cache_alloc;
istate->fsmonitor_has_run_once = 0;
FREE_AND_NULL(istate->fsmonitor_dirty);
FREE_AND_NULL(istate->fsmonitor_last_update);
strbuf_release(&base);
free(full);
/* Clear and recompute the cache-tree */
cache_tree_free(&istate->cache_tree);
cache_tree_update(istate, 0);
trace2_region_leave("index", tr_region, istate->repo);
}
void ensure_full_index(struct index_state *istate)
{
if (!istate)
BUG("ensure_full_index() must get an index!");
expand_index(istate, NULL);
}
void ensure_correct_sparsity(struct index_state *istate)
{
/*
* If the index can be sparse, make it sparse. Otherwise,
* ensure the index is full.
*/
if (is_sparse_index_allowed(istate, 0))
convert_to_sparse(istate, 0);
else
ensure_full_index(istate);
}
static int path_found(const char *path, const char **dirname, size_t *dir_len,
int *dir_found)
{
struct stat st;
char *newdir;
char *tmp;
/*
* If dirname corresponds to a directory that doesn't exist, and this
* path starts with dirname, then path can't exist.
*/
if (!*dir_found && !memcmp(path, *dirname, *dir_len))
return 0;
/*
* If path itself exists, return 1.
*/
if (!lstat(path, &st))
return 1;
/*
* Otherwise, path does not exist so we'll return 0...but we'll first
* determine some info about its parent directory so we can avoid
* lstat calls for future cache entries.
*/
newdir = strrchr(path, '/');
if (!newdir)
return 0; /* Didn't find a parent dir; just return 0 now. */
/*
* If path starts with directory (which we already lstat'ed and found),
* then no need to lstat parent directory again.
*/
if (*dir_found && *dirname && memcmp(path, *dirname, *dir_len))
return 0;
/* Free previous dirname, and cache path's dirname */
*dirname = path;
*dir_len = newdir - path + 1;
tmp = xstrndup(path, *dir_len);
*dir_found = !lstat(tmp, &st);
free(tmp);
return 0;
}
void clear_skip_worktree_from_present_files(struct index_state *istate)
{
const char *last_dirname = NULL;
size_t dir_len = 0;
int dir_found = 1;
int i;
int path_count[2] = {0, 0};
int restarted = 0;
if (!core_apply_sparse_checkout ||
sparse_expect_files_outside_of_patterns)
return;
trace2_region_enter("index", "clear_skip_worktree_from_present_files",
istate->repo);
restart:
for (i = 0; i < istate->cache_nr; i++) {
struct cache_entry *ce = istate->cache[i];
if (ce_skip_worktree(ce)) {
path_count[restarted]++;
if (path_found(ce->name, &last_dirname, &dir_len, &dir_found)) {
if (S_ISSPARSEDIR(ce->ce_mode)) {
if (restarted)
BUG("ensure-full-index did not fully flatten?");
ensure_full_index(istate);
restarted = 1;
goto restart;
}
ce->ce_flags &= ~CE_SKIP_WORKTREE;
}
}
}
if (path_count[0])
trace2_data_intmax("index", istate->repo,
"sparse_path_count", path_count[0]);
if (restarted)
trace2_data_intmax("index", istate->repo,
"sparse_path_count_full", path_count[1]);
trace2_region_leave("index", "clear_skip_worktree_from_present_files",
istate->repo);
}
/*
* This static global helps avoid infinite recursion between
* expand_to_path() and index_file_exists().
*/
static int in_expand_to_path = 0;
void expand_to_path(struct index_state *istate,
const char *path, size_t pathlen, int icase)
{
struct strbuf path_mutable = STRBUF_INIT;
size_t substr_len;
/* prevent extra recursion */
if (in_expand_to_path)
return;
if (!istate->sparse_index)
return;
in_expand_to_path = 1;
/*
* We only need to actually expand a region if the
* following are both true:
*
* 1. 'path' is not already in the index.
* 2. Some parent directory of 'path' is a sparse directory.
*/
if (index_file_exists(istate, path, pathlen, icase))
goto cleanup;
strbuf_add(&path_mutable, path, pathlen);
strbuf_addch(&path_mutable, '/');
/* Check the name hash for all parent directories */
substr_len = 0;
while (substr_len < pathlen) {
char temp;
char *replace = strchr(path_mutable.buf + substr_len, '/');
if (!replace)
break;
/* replace the character _after_ the slash */
replace++;
temp = *replace;
*replace = '\0';
if (index_file_exists(istate, path_mutable.buf,
path_mutable.len, icase)) {
/*
* We found a parent directory in the name-hash
* hashtable, because only sparse directory entries
* have a trailing '/' character. Since "path" wasn't
* in the index, perhaps it exists within this
* sparse-directory. Expand accordingly.
*/
ensure_full_index(istate);
break;
}
*replace = temp;
substr_len = replace - path_mutable.buf;
}
cleanup:
strbuf_release(&path_mutable);
in_expand_to_path = 0;
}