Function 'fileno' fails only if invalid pointer is passed, this is a
case that is often ignored in source code. The failure case leads to
many "false positive" reports when `fileno` returns -1 and this is not
checked in the program. Because this, the function is now assumed
to not fail (this is assumption that the passed file pointer is correct).
The change affects `StdCLibraryFunctionsChecker` and
`StreamChecker`.
The note tag that was previously added in all cases when a standard function call
is found is displayed now only if the function call (return value) is "interesting".
This results in less unneeded notes but some of the previously good notes disappear
too. This is because interestingness is not always set as it should be.
Reviewed By: donat.nagy
Differential Revision: https://reviews.llvm.org/D153776
Change 1: ErrnoChecker notes show only messages related to errno,
not to assumption of success or failure of functions.
Change 2: StdLibraryFunctionsChecker adds its own note about success
or failure of functions, and the errno related note, independently.
Change 3: Every modeled function in StdLibraryFunctionsChecker
should have a note tag message in all "cases". This is not implemented yet,
only for file (stream) related functions.
Reviewed By: donat.nagy
Differential Revision: https://reviews.llvm.org/D153612
Main reason for this change is that these checkers were implemented in the same class
but had different dependency ordering. (NonNullParamChecker should run before StdCLibraryFunctionArgs
to get more special warning about null arguments, but the apiModeling.StdCLibraryFunctions was a modeling
checker that should run before other non-modeling checkers. The modeling checker changes state in a way
that makes it impossible to detect a null argument by NonNullParamChecker.)
To make it more simple, the modeling part is removed as separate checker and can be only used if
checker StdCLibraryFunctions is turned on, that produces the warnings too. Modeling the functions
without bug detection (for invalid argument) is not possible. The modeling of standard functions
does not happen by default from this change on.
Reviewed By: Szelethus
Differential Revision: https://reviews.llvm.org/D151225
The patch is straightforward except the tiny fix in BugReporterVisitors.cpp
that suppresses a default note for "Assuming pointer value is null" when
a note tag from the checker is present. This is probably the right thing to do
but also definitely not a complete solution to the problem of different sources
of path notes being unaware of each other, which is a large and annoying issue
that we have to deal with. Note tags really help there because they're nicely
introspectable. The problem is demonstrated by the newly added getenv() test.
Differential Revision: https://reviews.llvm.org/D122285
