thodg/libgit2/fuzzers/midx_fuzzer.c

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• Hash : 489aec44
  Author :
  Date : 2021-11-11T12:33:14
  

  fuzzers: declare standalone functions

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• fuzzers/midx_fuzzer.c

• /*
   * libgit2 multi-pack-index 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 "common.h"
  #include "futils.h"
  #include "hash.h"
  #include "midx.h"
  
  #include "standalone_driver.h"
  
  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();
  	}
  	return 0;
  }
  
  int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
  {
  	git_midx_file idx = {{0}};
  	git_midx_entry e;
  	git_str midx_buf = GIT_STR_INIT;
  	unsigned char hash[GIT_HASH_SHA1_SIZE];
  	git_oid oid = {{0}};
  	bool append_hash = false;
  
  	if (size < 4)
  		return 0;
  
  	/*
  	 * 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;
  	/* Keep a 4-byte alignment to avoid unaligned accesses. */
  	data += 4;
  	size -= 4;
  
  	if (append_hash) {
  		if (git_str_init(&midx_buf, size + GIT_HASH_SHA1_SIZE) < 0)
  			goto cleanup;
  		if (git_hash_buf(hash, data, size, GIT_HASH_ALGORITHM_SHA1) < 0) {
  			fprintf(stderr, "Failed to compute the SHA1 hash\n");
  			abort();
  		}
  		memcpy(midx_buf.ptr, data, size);
  		memcpy(midx_buf.ptr + size, hash, GIT_HASH_SHA1_SIZE);
  
  		memcpy(oid.id, hash, GIT_OID_RAWSZ);
  	} else {
  		git_str_attach_notowned(&midx_buf, (char *)data, size);
  	}
  
  	if (git_midx_parse(&idx, (const unsigned char *)git_str_cstr(&midx_buf), git_str_len(&midx_buf)) < 0)
  		goto cleanup;
  
  	/* Search for any oid, just to exercise that codepath. */
  	if (git_midx_entry_find(&e, &idx, &oid, GIT_OID_HEXSZ) < 0)
  		goto cleanup;
  
  cleanup:
  	git_midx_close(&idx);
  	git_str_dispose(&midx_buf);
  	return 0;
  }
  

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