thodg/libgit2/fuzzers/commit_graph_fuzzer.c

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• Hash : 1f32ed25
  Author :
  Date : 2021-01-04T19:33:48
  

  commit-graph: Support lookups of entries in a commit-graph
  
  This change introduces `git_commit_graph_entry_find()` and
  `git_commit_graph_entry_parent()`. These two functions allow a much
  faster lookup of commits by ID, since the ODB does not need to be
  consulted, the commit object does not need to be inflated, and the
  contents of the commit object do not need to be parsed.
  
  Part of: #5757
  

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• fuzzers/commit_graph_fuzzer.c

• /*
   * libgit2 commit-graph 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 "buffer.h"
  #include "common.h"
  #include "futils.h"
  #include "hash.h"
  #include "commit_graph.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_commit_graph_file cgraph = {{0}};
  	git_commit_graph_entry e;
  	git_buf commit_graph_buf = GIT_BUF_INIT;
  	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 file 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_buf_init(&commit_graph_buf, size + sizeof(oid)) < 0)
  			goto cleanup;
  		if (git_hash_buf(&oid, data, size) < 0) {
  			fprintf(stderr, "Failed to compute the SHA1 hash\n");
  			abort();
  		}
  		memcpy(commit_graph_buf.ptr, data, size);
  		memcpy(commit_graph_buf.ptr + size, &oid, sizeof(oid));
  	} else {
  		git_buf_attach_notowned(&commit_graph_buf, (char *)data, size);
  	}
  
  	if (git_commit_graph_parse(
  			    &cgraph,
  			    (const unsigned char *)git_buf_cstr(&commit_graph_buf),
  			    git_buf_len(&commit_graph_buf))
  	    < 0)
  		goto cleanup;
  
  	/* Search for any oid, just to exercise that codepath. */
  	if (git_commit_graph_entry_find(&e, &cgraph, &oid, GIT_OID_HEXSZ) < 0)
  		goto cleanup;
  
  cleanup:
  	git_commit_graph_close(&cgraph);
  	git_buf_dispose(&commit_graph_buf);
  	return 0;
  }
  

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