thodg/libgit2/fuzz/fuzz_packfile_raw.c

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• Hash : 60e610a2
  Author :
  Date : 2018-01-04T15:36:22
  

  fuzzers: add build support and instructions This change adds support for building a fuzz target for exercising the packfile parser, as well as documentation. It also runs the fuzzers in Travis to avoid regressions.

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• fuzz/fuzz_packfile_raw.c

• /*
   * libgit2 raw packfile fuzz 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 <stdbool.h>
  #include <stdint.h>
  #include <stdio.h>
  
  #include "fileops.h"
  #include "hash.h"
  #include "git2.h"
  #include "git2/sys/mempack.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_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 *indexer = NULL;
  	git_transfer_progress stats = {0, 0};
  	bool append_hash = false;
  	git_oid id;
  	char hash[GIT_OID_HEXSZ + 1] = {0};
  	char path[PATH_MAX];
  
  	if (size == 0)
  		return 0;
  
  	if (!odb || !mempack) {
  		fprintf(stderr, "Global state not initialized\n");
  		abort();
  	}
  	git_mempack_reset(mempack);
  
  	if (git_odb_write(&id, odb, base_obj, base_obj_len, GIT_OBJ_BLOB) < 0) {
  		fprintf(stderr, "Failed to add an object to the odb\n");
  		abort();
  	}
  
  	if (git_indexer_new(&indexer, ".", 0, odb, NULL, NULL) < 0) {
  		fprintf(stderr, "Failed to create the indexer: %s\n",
  			giterr_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) {
  		git_oid oid;
  		if (git_hash_buf(&oid, data, size) < 0) {
  			fprintf(stderr, "Failed to compute the SHA1 hash\n");
  			abort();
  		}
  		if (git_indexer_append(indexer, &oid, sizeof(oid), &stats) < 0) {
  			goto cleanup;
  		}
  	}
  	if (git_indexer_commit(indexer, &stats) < 0)
  		goto cleanup;
  
  	/*
  	 * We made it! We managed to produce a valid packfile.
  	 * Let's clean it up.
  	 */
  	git_oid_fmt(hash, git_indexer_hash(indexer));
  	printf("Generated packfile %s\n", hash);
  	snprintf(path, sizeof(path), "pack-%s.idx", hash);
  	unlink(path);
  	snprintf(path, sizeof(path), "pack-%s.pack", hash);
  	unlink(path);
  
  cleanup:
  	git_mempack_reset(mempack);
  	git_indexer_free(indexer);
  	return 0;
  }
  

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