inputStructSize
inputStructSize is a field name used in some APIs to indicate the size, in bytes, of an input structure passed to a function. The concept is common in systems programming, where structures may evolve over time and compatibility between versions must be managed carefully.
The primary purpose of inputStructSize is to enable versioning and memory safety. By knowing how many bytes
- verify that the received data is at least large enough to contain the required fields
- decide which optional or version-specific fields are present
- protect against reading beyond the end of the supplied data
This pattern helps maintain backward and forward compatibility when structures are extended with new members in
- The caller fills the structure and sets inputStructSize to the size of the structure being sent.
- The callee checks inputStructSize to determine which fields are valid and how to interpret the payload.
- If inputStructSize is smaller than the minimum required size, the function can return an error; if
Example in plain language: a program constructs a config input, sets inputStructSize = sizeof(ConfigInput), and passes it
Similar ideas exist under names like cbSize or dwSize in other APIs. The exact field name varies
cbSize, dwSize, structure versioning, backward compatibility, memory safety.