thodg/libgit2/src/hash.c

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• Hash : f0e693b1
  Author :
  Date : 2021-09-07T17:53:49
  

  str: introduce `git_str` for internal, `git_buf` is external
  
  libgit2 has two distinct requirements that were previously solved by
  `git_buf`.  We require:
  
  1. A general purpose string class that provides a number of utility APIs
     for manipulating data (eg, concatenating, truncating, etc).
  2. A structure that we can use to return strings to callers that they
     can take ownership of.
  
  By using a single class (`git_buf`) for both of these purposes, we have
  confused the API to the point that refactorings are difficult and
  reasoning about correctness is also difficult.
  
  Move the utility class `git_buf` to be called `git_str`: this represents
  its general purpose, as an internal string buffer class.  The name also
  is an homage to Junio Hamano ("gitstr").
  
  The public API remains `git_buf`, and has a much smaller footprint.  It
  is generally only used as an "out" param with strict requirements that
  follow the documentation.  (Exceptions exist for some legacy APIs to
  avoid breaking callers unnecessarily.)
  
  Utility functions exist to convert a user-specified `git_buf` to a
  `git_str` so that we can call internal functions, then converting it
  back again.
  

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• src/hash.c

• /*
   * 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 "hash.h"
  
  int git_hash_global_init(void)
  {
  	return git_hash_sha1_global_init();
  }
  
  int git_hash_ctx_init(git_hash_ctx *ctx, git_hash_algorithm_t algorithm)
  {
  	int error;
  
  	switch (algorithm) {
  	case GIT_HASH_ALGORITHM_SHA1:
  		error = git_hash_sha1_ctx_init(&ctx->ctx.sha1);
  		break;
  	default:
  		git_error_set(GIT_ERROR_INTERNAL, "unknown hash algorithm");
  		error = -1;
  	}
  
  	ctx->algorithm = algorithm;
  	return error;
  }
  
  void git_hash_ctx_cleanup(git_hash_ctx *ctx)
  {
  	switch (ctx->algorithm) {
  	case GIT_HASH_ALGORITHM_SHA1:
  		git_hash_sha1_ctx_cleanup(&ctx->ctx.sha1);
  		return;
  	default:
  		/* unreachable */ ;
  	}
  }
  
  int git_hash_init(git_hash_ctx *ctx)
  {
  	switch (ctx->algorithm) {
  	case GIT_HASH_ALGORITHM_SHA1:
  		return git_hash_sha1_init(&ctx->ctx.sha1);
  	default:
  		/* unreachable */ ;
  	}
  
  	git_error_set(GIT_ERROR_INTERNAL, "unknown hash algorithm");
  	return -1;
  }
  
  int git_hash_update(git_hash_ctx *ctx, const void *data, size_t len)
  {
  	switch (ctx->algorithm) {
  	case GIT_HASH_ALGORITHM_SHA1:
  		return git_hash_sha1_update(&ctx->ctx.sha1, data, len);
  	default:
  		/* unreachable */ ;
  	}
  
  	git_error_set(GIT_ERROR_INTERNAL, "unknown hash algorithm");
  	return -1;
  }
  
  int git_hash_final(unsigned char *out, git_hash_ctx *ctx)
  {
  	switch (ctx->algorithm) {
  	case GIT_HASH_ALGORITHM_SHA1:
  		return git_hash_sha1_final(out, &ctx->ctx.sha1);
  	default:
  		/* unreachable */ ;
  	}
  
  	git_error_set(GIT_ERROR_INTERNAL, "unknown hash algorithm");
  	return -1;
  }
  
  int git_hash_buf(
  	unsigned char *out,
  	const void *data,
  	size_t len,
  	git_hash_algorithm_t algorithm)
  {
  	git_hash_ctx ctx;
  	int error = 0;
  
  	if (git_hash_ctx_init(&ctx, algorithm) < 0)
  		return -1;
  
  	if ((error = git_hash_update(&ctx, data, len)) >= 0)
  		error = git_hash_final(out, &ctx);
  
  	git_hash_ctx_cleanup(&ctx);
  
  	return error;
  }
  
  int git_hash_vec(
  	unsigned char *out,
  	git_str_vec *vec,
  	size_t n,
  	git_hash_algorithm_t algorithm)
  {
  	git_hash_ctx ctx;
  	size_t i;
  	int error = 0;
  
  	if (git_hash_ctx_init(&ctx, algorithm) < 0)
  		return -1;
  
  	for (i = 0; i < n; i++) {
  		if ((error = git_hash_update(&ctx, vec[i].data, vec[i].len)) < 0)
  			goto done;
  	}
  
  	error = git_hash_final(out, &ctx);
  
  done:
  	git_hash_ctx_cleanup(&ctx);
  
  	return error;
  }
  

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