thodg/libgit2/src/alloc.c
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Hash : 08f28ff5
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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
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/* * 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; }