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file_util: Early-exit in WriteArray and ReadArray if specified lengths are zero

It's undefined behavior to pass a null pointer to std::fread and
std::fwrite, even if the length passed in is zero, so we must perform
the precondition checking ourselves.

A common case where this can occur is when passing in the data of an
empty std::vector and size, as an empty vector will typically have a
null internal buffer.

While we're at it, we can move the implementation out of line and add
debug checks against passing in nullptr to std::fread and std::fwrite.
This commit is contained in:
Lioncash 2020-04-15 14:21:22 -04:00
parent 64b5985f0a
commit e77337588e
2 changed files with 33 additions and 9 deletions

View file

@ -967,6 +967,34 @@ bool IOFile::Flush() {
return IsOpen() && 0 == std::fflush(m_file);
}
std::size_t IOFile::ReadImpl(void* data, std::size_t length, std::size_t data_size) const {
if (!IsOpen()) {
return std::numeric_limits<std::size_t>::max();
}
if (length == 0) {
return 0;
}
DEBUG_ASSERT(data != nullptr);
return std::fread(data, data_size, length, m_file);
}
std::size_t IOFile::WriteImpl(const void* data, std::size_t length, std::size_t data_size) {
if (!IsOpen()) {
return std::numeric_limits<std::size_t>::max();
}
if (length == 0) {
return 0;
}
DEBUG_ASSERT(data != nullptr);
return std::fwrite(data, data_size, length, m_file);
}
bool IOFile::Resize(u64 size) {
return IsOpen() && 0 ==
#ifdef _WIN32

View file

@ -222,22 +222,15 @@ public:
static_assert(std::is_trivially_copyable_v<T>,
"Given array does not consist of trivially copyable objects");
if (!IsOpen()) {
return std::numeric_limits<std::size_t>::max();
}
return std::fread(data, sizeof(T), length, m_file);
return ReadImpl(data, length, sizeof(T));
}
template <typename T>
std::size_t WriteArray(const T* data, std::size_t length) {
static_assert(std::is_trivially_copyable_v<T>,
"Given array does not consist of trivially copyable objects");
if (!IsOpen()) {
return std::numeric_limits<std::size_t>::max();
}
return std::fwrite(data, sizeof(T), length, m_file);
return WriteImpl(data, length, sizeof(T));
}
template <typename T>
@ -278,6 +271,9 @@ public:
}
private:
std::size_t ReadImpl(void* data, std::size_t length, std::size_t data_size) const;
std::size_t WriteImpl(const void* data, std::size_t length, std::size_t data_size);
std::FILE* m_file = nullptr;
};