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c++crt

CRT 9.0 vsprintf_s Parameter Validation on a long format string

From here:

The versions of these functions with _s and _p suffixes are the more secure versions. These versions validate the format strings and will generate an exception if the format string is not well formed (for example, if invalid formatting characters are used).

I just discovered the format string is considered not well formed if it is larger than the output buffer size. Does anyone know of documentation that confirms this for all *_s print functions?

Thanks

Solution

  • Looks like the default behavior is to throw the CRT error if output buffer size is exceeded, regardless of source. I expected the output to be silently truncated if the output buffer size is exceeded. Thus, there is no point in attempting to fill in the format string if it is too long already.