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![Jeff King](/assets/img/avatar_default.png)
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>
224 lines
5.2 KiB
C
224 lines
5.2 KiB
C
#include "git-compat-util.h"
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#include "cache-tree.h"
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#include "hex.h"
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#include "tree.h"
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#include "object-name.h"
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#include "object-store-ll.h"
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#include "blob.h"
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#include "commit.h"
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#include "tag.h"
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#include "alloc.h"
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#include "tree-walk.h"
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#include "repository.h"
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#include "environment.h"
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const char *tree_type = "tree";
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int read_tree_at(struct repository *r,
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struct tree *tree, struct strbuf *base,
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int depth,
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const struct pathspec *pathspec,
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read_tree_fn_t fn, void *context)
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{
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struct tree_desc desc;
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struct name_entry entry;
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struct object_id oid;
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int len, oldlen = base->len;
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enum interesting retval = entry_not_interesting;
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if (depth > max_allowed_tree_depth)
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return error("exceeded maximum allowed tree depth");
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if (parse_tree(tree))
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return -1;
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init_tree_desc(&desc, tree->buffer, tree->size);
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while (tree_entry(&desc, &entry)) {
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if (retval != all_entries_interesting) {
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retval = tree_entry_interesting(r->index, &entry,
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base, pathspec);
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if (retval == all_entries_not_interesting)
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break;
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if (retval == entry_not_interesting)
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continue;
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}
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switch (fn(&entry.oid, base,
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entry.path, entry.mode, context)) {
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case 0:
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continue;
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case READ_TREE_RECURSIVE:
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break;
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default:
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return -1;
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}
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if (S_ISDIR(entry.mode))
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oidcpy(&oid, &entry.oid);
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else if (S_ISGITLINK(entry.mode)) {
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struct commit *commit;
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commit = lookup_commit(r, &entry.oid);
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if (!commit)
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die("Commit %s in submodule path %s%s not found",
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oid_to_hex(&entry.oid),
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base->buf, entry.path);
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if (repo_parse_commit(r, commit))
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die("Invalid commit %s in submodule path %s%s",
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oid_to_hex(&entry.oid),
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base->buf, entry.path);
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oidcpy(&oid, get_commit_tree_oid(commit));
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}
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else
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continue;
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len = tree_entry_len(&entry);
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strbuf_add(base, entry.path, len);
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strbuf_addch(base, '/');
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retval = read_tree_at(r, lookup_tree(r, &oid),
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base, depth + 1, pathspec,
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fn, context);
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strbuf_setlen(base, oldlen);
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if (retval)
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return -1;
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}
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return 0;
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}
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int read_tree(struct repository *r,
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struct tree *tree,
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const struct pathspec *pathspec,
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read_tree_fn_t fn, void *context)
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{
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struct strbuf sb = STRBUF_INIT;
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int ret = read_tree_at(r, tree, &sb, 0, pathspec, fn, context);
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strbuf_release(&sb);
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return ret;
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}
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int base_name_compare(const char *name1, size_t len1, int mode1,
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const char *name2, size_t len2, int mode2)
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{
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unsigned char c1, c2;
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size_t len = len1 < len2 ? len1 : len2;
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int cmp;
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cmp = memcmp(name1, name2, len);
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if (cmp)
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return cmp;
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c1 = name1[len];
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c2 = name2[len];
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if (!c1 && S_ISDIR(mode1))
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c1 = '/';
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if (!c2 && S_ISDIR(mode2))
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c2 = '/';
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return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
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}
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/*
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* df_name_compare() is identical to base_name_compare(), except it
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* compares conflicting directory/file entries as equal. Note that
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* while a directory name compares as equal to a regular file, they
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* then individually compare _differently_ to a filename that has
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* a dot after the basename (because '\0' < '.' < '/').
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*
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* This is used by routines that want to traverse the git namespace
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* but then handle conflicting entries together when possible.
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*/
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int df_name_compare(const char *name1, size_t len1, int mode1,
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const char *name2, size_t len2, int mode2)
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{
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unsigned char c1, c2;
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size_t len = len1 < len2 ? len1 : len2;
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int cmp;
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cmp = memcmp(name1, name2, len);
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if (cmp)
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return cmp;
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/* Directories and files compare equal (same length, same name) */
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if (len1 == len2)
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return 0;
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c1 = name1[len];
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if (!c1 && S_ISDIR(mode1))
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c1 = '/';
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c2 = name2[len];
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if (!c2 && S_ISDIR(mode2))
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c2 = '/';
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if (c1 == '/' && !c2)
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return 0;
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if (c2 == '/' && !c1)
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return 0;
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return c1 - c2;
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}
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int name_compare(const char *name1, size_t len1, const char *name2, size_t len2)
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{
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size_t min_len = (len1 < len2) ? len1 : len2;
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int cmp = memcmp(name1, name2, min_len);
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if (cmp)
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return cmp;
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if (len1 < len2)
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return -1;
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if (len1 > len2)
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return 1;
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return 0;
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}
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struct tree *lookup_tree(struct repository *r, const struct object_id *oid)
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{
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struct object *obj = lookup_object(r, oid);
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if (!obj)
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return create_object(r, oid, alloc_tree_node(r));
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return object_as_type(obj, OBJ_TREE, 0);
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}
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int parse_tree_buffer(struct tree *item, void *buffer, unsigned long size)
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{
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if (item->object.parsed)
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return 0;
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item->object.parsed = 1;
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item->buffer = buffer;
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item->size = size;
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return 0;
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}
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int parse_tree_gently(struct tree *item, int quiet_on_missing)
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{
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enum object_type type;
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void *buffer;
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unsigned long size;
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if (item->object.parsed)
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return 0;
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buffer = repo_read_object_file(the_repository, &item->object.oid,
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&type, &size);
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if (!buffer)
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return quiet_on_missing ? -1 :
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error("Could not read %s",
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oid_to_hex(&item->object.oid));
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if (type != OBJ_TREE) {
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free(buffer);
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return error("Object %s not a tree",
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oid_to_hex(&item->object.oid));
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}
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return parse_tree_buffer(item, buffer, size);
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}
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void free_tree_buffer(struct tree *tree)
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{
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FREE_AND_NULL(tree->buffer);
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tree->size = 0;
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tree->object.parsed = 0;
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}
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struct tree *parse_tree_indirect(const struct object_id *oid)
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{
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struct repository *r = the_repository;
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struct object *obj = parse_object(r, oid);
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return (struct tree *)repo_peel_to_type(r, NULL, 0, obj, OBJ_TREE);
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}
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