thodg/libgit2/src/alloc.c

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• Hash : 08f28ff5
  Author :
  Date : 2020-07-10T08:57:05
  

  alloc: set up an allocator that fails before library init
  
  We require the library to be initialized with git_libgit2_init before it
  is functional.  However, if a user tries to uses the library without
  doing so - as they might when getting started with the library for the
  first time - we will likely crash.
  
  This commit introduces some guard rails - now instead of having _no_
  allocator by default, we'll have an allocator that always fails, and
  never tries to set an error message (since the thread-local state is
  set up by git_libgit2_init).  We've modified the error retrieval
  function to (try to) ensure that the library has been initialized before
  getting the thread-local error message.
  
  (Unfortunately, we cannot determine if the thread local storage has
  actually been configured, this does require initialization by
  git_libgit2_init.  But a naive attempt should be good enough for most
  cases.)
  

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• src/alloc.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 "alloc.h"
  #include "runtime.h"
  
  #include "allocators/failalloc.h"
  #include "allocators/stdalloc.h"
  #include "allocators/win32_leakcheck.h"
  
  /* Fail any allocation until git_libgit2_init is called. */
  git_allocator git__allocator = {
  	git_failalloc_malloc,
  	git_failalloc_calloc,
  	git_failalloc_strdup,
  	git_failalloc_strndup,
  	git_failalloc_substrdup,
  	git_failalloc_realloc,
  	git_failalloc_reallocarray,
  	git_failalloc_mallocarray,
  	git_failalloc_free
  };
  
  static int setup_default_allocator(void)
  {
  #if defined(GIT_WIN32_LEAKCHECK)
  	return git_win32_leakcheck_init_allocator(&git__allocator);
  #else
  	return git_stdalloc_init_allocator(&git__allocator);
  #endif
  }
  
  int git_allocator_global_init(void)
  {
  	/*
  	 * We don't want to overwrite any allocator which has been set
  	 * before the init function is called.
  	 */
  	if (git__allocator.gmalloc != git_failalloc_malloc)
  		return 0;
  
  	return setup_default_allocator();
  }
  
  int git_allocator_setup(git_allocator *allocator)
  {
  	if (!allocator)
  		return setup_default_allocator();
  
  	memcpy(&git__allocator, allocator, sizeof(*allocator));
  	return 0;
  }
  

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