thodg/libgit2/src/ident.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/ident.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 "common.h"
  
  #include "git2/sys/filter.h"
  #include "filter.h"
  #include "str.h"
  
  static int ident_find_id(
  	const char **id_start, const char **id_end, const char *start, size_t len)
  {
  	const char *end = start + len, *found = NULL;
  
  	while (len > 3 && (found = memchr(start, '$', len)) != NULL) {
  		size_t remaining = (size_t)(end - found) - 1;
  		if (remaining < 3)
  			return GIT_ENOTFOUND;
  
  		start = found + 1;
  		len   = remaining;
  
  		if (start[0] == 'I' && start[1] == 'd')
  			break;
  	}
  
  	if (len < 3 || !found)
  		return GIT_ENOTFOUND;
  	*id_start = found;
  
  	if ((found = memchr(start + 2, '$', len - 2)) == NULL)
  		return GIT_ENOTFOUND;
  
  	*id_end = found + 1;
  	return 0;
  }
  
  static int ident_insert_id(
  	git_str *to, const git_str *from, const git_filter_source *src)
  {
  	char oid[GIT_OID_HEXSZ+1];
  	const char *id_start, *id_end, *from_end = from->ptr + from->size;
  	size_t need_size;
  
  	/* replace $Id$ with blob id */
  
  	if (!git_filter_source_id(src))
  		return GIT_PASSTHROUGH;
  
  	git_oid_tostr(oid, sizeof(oid), git_filter_source_id(src));
  
  	if (ident_find_id(&id_start, &id_end, from->ptr, from->size) < 0)
  		return GIT_PASSTHROUGH;
  
  	need_size = (size_t)(id_start - from->ptr) +
  		5 /* "$Id: " */ + GIT_OID_HEXSZ + 2 /* " $" */ +
  		(size_t)(from_end - id_end);
  
  	if (git_str_grow(to, need_size) < 0)
  		return -1;
  
  	git_str_set(to, from->ptr, (size_t)(id_start - from->ptr));
  	git_str_put(to, "$Id: ", 5);
  	git_str_put(to, oid, GIT_OID_HEXSZ);
  	git_str_put(to, " $", 2);
  	git_str_put(to, id_end, (size_t)(from_end - id_end));
  
  	return git_str_oom(to) ? -1 : 0;
  }
  
  static int ident_remove_id(
  	git_str *to, const git_str *from)
  {
  	const char *id_start, *id_end, *from_end = from->ptr + from->size;
  	size_t need_size;
  
  	if (ident_find_id(&id_start, &id_end, from->ptr, from->size) < 0)
  		return GIT_PASSTHROUGH;
  
  	need_size = (size_t)(id_start - from->ptr) +
  		4 /* "$Id$" */ + (size_t)(from_end - id_end);
  
  	if (git_str_grow(to, need_size) < 0)
  		return -1;
  
  	git_str_set(to, from->ptr, (size_t)(id_start - from->ptr));
  	git_str_put(to, "$Id$", 4);
  	git_str_put(to, id_end, (size_t)(from_end - id_end));
  
  	return git_str_oom(to) ? -1 : 0;
  }
  
  static int ident_apply(
  	git_filter     *self,
  	void          **payload,
  	git_str        *to,
  	const git_str  *from,
  	const git_filter_source *src)
  {
  	GIT_UNUSED(self); GIT_UNUSED(payload);
  
  	/* Don't filter binary files */
  	if (git_str_is_binary(from))
  		return GIT_PASSTHROUGH;
  
  	if (git_filter_source_mode(src) == GIT_FILTER_SMUDGE)
  		return ident_insert_id(to, from, src);
  	else
  		return ident_remove_id(to, from);
  }
  
  static int ident_stream(
  	git_writestream **out,
  	git_filter *self,
  	void **payload,
  	const git_filter_source *src,
  	git_writestream *next)
  {
  	return git_filter_buffered_stream_new(out,
  		self, ident_apply, NULL, payload, src, next);
  }
  
  git_filter *git_ident_filter_new(void)
  {
  	git_filter *f = git__calloc(1, sizeof(git_filter));
  	if (f == NULL)
  		return NULL;
  
  	f->version = GIT_FILTER_VERSION;
  	f->attributes = "+ident"; /* apply to files with ident attribute set */
  	f->shutdown = git_filter_free;
  	f->stream   = ident_stream;
  
  	return f;
  }
  

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