Files
libgit2/fuzzers/packfile_fuzzer.c
Edward Thomson 56e2a85643 sha256: simplify API changes for sha256 support
There are several places where users may want to specify the type of
object IDs (sha1 or sha256) that should be used, for example, when
dealing with repositories, indexes, etc.

However, given that sha256 support remains disappointingly uncommon in
the wild, we should avoid hard API breaks when possible. Instead, update
these APIs to have an "extended" format (eg, `git_odb_open_ext`) that
provides an options structure with oid type information.

This allows callers who do care about sha256 to use it, and callers who
do not to avoid gratuitous API breakage.
2025-01-02 13:13:59 +00:00

137 lines
3.1 KiB
C

/*
* libgit2 packfile fuzzer target.
*
* Copyright (C) the libgit2 contributors. All rights reserved.
*
* This file is part of libgit2, distributed under the GNU GPL v2 with
* a Linking Exception. For full terms see the included COPYING file.
*/
#include <stdio.h>
#include "git2.h"
#include "git2/sys/mempack.h"
#include "common.h"
#include "str.h"
#include "standalone_driver.h"
static git_odb *odb = NULL;
static git_odb_backend *mempack = NULL;
/* Arbitrary object to seed the ODB. */
static const unsigned char base_obj[] = { 07, 076 };
static const unsigned int base_obj_len = 2;
int LLVMFuzzerInitialize(int *argc, char ***argv)
{
GIT_UNUSED(argc);
GIT_UNUSED(argv);
if (git_libgit2_init() < 0) {
fprintf(stderr, "Failed to initialize libgit2\n");
abort();
}
if (git_libgit2_opts(GIT_OPT_SET_PACK_MAX_OBJECTS, 10000000) < 0) {
fprintf(stderr, "Failed to limit maximum pack object count\n");
abort();
}
if (git_odb_new(&odb) < 0) {
fprintf(stderr, "Failed to create the odb\n");
abort();
}
if (git_mempack_new(&mempack) < 0) {
fprintf(stderr, "Failed to create the mempack\n");
abort();
}
if (git_odb_add_backend(odb, mempack, 999) < 0) {
fprintf(stderr, "Failed to add the mempack\n");
abort();
}
return 0;
}
int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
git_indexer_progress stats = {0, 0};
git_indexer *indexer = NULL;
git_str path = GIT_STR_INIT;
git_oid oid;
bool append_hash = false;
int error;
if (size == 0)
return 0;
if (!odb || !mempack) {
fprintf(stderr, "Global state not initialized\n");
abort();
}
git_mempack_reset(mempack);
if (git_odb_write(&oid, odb, base_obj, base_obj_len, GIT_OBJECT_BLOB) < 0) {
fprintf(stderr, "Failed to add an object to the odb\n");
abort();
}
#ifdef GIT_EXPERIMENTAL_SHA256
error = git_indexer_new(&indexer, ".", NULL);
#else
error = git_indexer_new(&indexer, ".", 0, odb, NULL);
#endif
if (error < 0) {
fprintf(stderr, "Failed to create the indexer: %s\n",
git_error_last()->message);
abort();
}
/*
* If the first byte in the stream has the high bit set, append the
* SHA1 hash so that the packfile is somewhat valid.
*/
append_hash = *data & 0x80;
++data;
--size;
if (git_indexer_append(indexer, data, size, &stats) < 0)
goto cleanup;
if (append_hash) {
#ifdef GIT_EXPERIMENTAL_SHA256
if (git_odb_hash(&oid, data, size, GIT_OBJECT_BLOB, GIT_OID_SHA1) < 0) {
fprintf(stderr, "Failed to compute the SHA1 hash\n");
abort();
}
#else
if (git_odb_hash(&oid, data, size, GIT_OBJECT_BLOB) < 0) {
fprintf(stderr, "Failed to compute the SHA1 hash\n");
abort();
}
#endif
if (git_indexer_append(indexer, &oid.id, GIT_OID_SHA1_SIZE, &stats) < 0) {
goto cleanup;
}
}
if (git_indexer_commit(indexer, &stats) < 0)
goto cleanup;
if (git_str_printf(&path, "pack-%s.idx", git_indexer_name(indexer)) < 0)
goto cleanup;
p_unlink(git_str_cstr(&path));
git_str_clear(&path);
if (git_str_printf(&path, "pack-%s.pack", git_indexer_name(indexer)) < 0)
goto cleanup;
p_unlink(git_str_cstr(&path));
cleanup:
git_mempack_reset(mempack);
git_indexer_free(indexer);
git_str_dispose(&path);
return 0;
}