[C++][Gandiva] Cache size can be negative number

[zanmato1984]

Describe the bug, including details regarding any error messages, version, and platform.

I think the original purpose of the following check is to set gandiva cache size to the predefined default value (5000) for invalid/zero/negative numbers:

arrow/cpp/src/gandiva/cache.cc

Lines 29 to 42 in 25bb627

	size_t capacity = DEFAULT_CACHE_SIZE;
	auto maybe_env_cache_size = ::arrow::internal::GetEnvVar("GANDIVA_CACHE_SIZE");
	if (maybe_env_cache_size.ok()) {
	const auto env_cache_size = *std::move(maybe_env_cache_size);
	if (!env_cache_size.empty()) {
	capacity = std::atol(env_cache_size.c_str());
	if (capacity <= 0) {
	ARROW_LOG(WARNING) << "Invalid cache size provided in GANDIVA_CACHE_SIZE. "
	<< "Using default cache size: " << DEFAULT_CACHE_SIZE;
	capacity = DEFAULT_CACHE_SIZE;
	}
	}
	}
	return static_cast<int>(capacity);

However it will fail checking if the value is negative because it is using unsigned type size_t to do the <= 0 check.

Component(s)

C++

[pitrou]

Issue resolved by pull request 41330
#41330