thodg/libgit2/tests/buf/oom.c

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• Hash : 2e34efaa
  Author :
  Date : 2018-10-21T13:10:06
  

  buf::oom tests: use custom allocator for oom failures
  
  Create a custom allocator for the `buf::oom` tests that will fail with
  out-of-memory errors in predictable ways.  We were previously trying to
  guess the way that various allocators on various platforms would fail
  in a way such that `malloc`/`realloc` would return `NULL` (instead of
  aborting the application, or appearing suspicious to various
  instrumentation or static code analysis tools like valgrind.)
  
  Introduce a fake `malloc` and `realloc` that will return `NULL` on
  allocations requesting more than 100 bytes.  Otherwise, we proxy to the
  default allocator.  (It's important to use the _default_ allocator, not
  just call `malloc`, since the default allocator on Windows CI builds may
  be the debugging C runtime allocators which would not be compatible with
  a standard `malloc`.)
  

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• tests/buf/oom.c

• #include "clar_libgit2.h"
  #include "buffer.h"
  
  /* Override default allocators with ones that will fail predictably. */
  
  static git_allocator std_alloc;
  static git_allocator oom_alloc;
  
  static void *oom_malloc(size_t n, const char *file, int line)
  {
  	/* Reject any allocation of more than 100 bytes */
  	return (n > 100) ? NULL : std_alloc.gmalloc(n, file, line);
  }
  
  static void *oom_realloc(void *p, size_t n, const char *file, int line)
  {
  	/* Reject any allocation of more than 100 bytes */
  	return (n > 100) ? NULL : std_alloc.grealloc(p, n, file, line);
  }
  
  void test_buf_oom__initialize(void)
  {
  	git_stdalloc_init_allocator(&std_alloc);
  	git_stdalloc_init_allocator(&oom_alloc);
  
  	oom_alloc.gmalloc = oom_malloc;
  	oom_alloc.grealloc = oom_realloc;
  
  	cl_git_pass(git_libgit2_opts(GIT_OPT_SET_ALLOCATOR, &oom_alloc));
  }
  
  void test_buf_oom__cleanup(void)
  {
  	cl_git_pass(git_libgit2_opts(GIT_OPT_SET_ALLOCATOR, NULL));
  }
  
  void test_buf_oom__grow(void)
  {
  	git_buf buf = GIT_BUF_INIT;
  
  	cl_git_pass(git_buf_grow(&buf, 42));
  	cl_assert(!git_buf_oom(&buf));
  
  	cl_assert(git_buf_grow(&buf, 101) == -1);
  	cl_assert(git_buf_oom(&buf));
  
  	git_buf_dispose(&buf);
  }
  
  void test_buf_oom__grow_by(void)
  {
  	git_buf buf = GIT_BUF_INIT;
  
  	cl_git_pass(git_buf_grow_by(&buf, 42));
  	cl_assert(!git_buf_oom(&buf));
  
  	cl_assert(git_buf_grow_by(&buf, 101) == -1);
  	cl_assert(git_buf_oom(&buf));
  }
  

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