thodg/libgit2/fuzzers/packfile_fuzzer.c

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• Hash : 59328ed8
  Author :
  Date : 2018-07-19T13:29:46
  

  fuzzers: rename "fuzz" directory to match our style
  
  Our layout uses names like "examples" or "tests" which is why the "fuzz"
  directory doesn't really fit in here. Rename the directory to be called
  "fuzzers" instead. Furthermore, we rename the fuzzer "fuzz_packfile_raw"
  to "packfile_raw_fuzzer", which is also in line with the already
  existing fuzzer at google/oss-fuzz.
  
  While at it, rename the "packfile_raw" fuzzer to instead just be called
  "packfile" fuzzer.
  

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• fuzzers/packfile_fuzzer.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 <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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