balazske added a comment.
> No matter what happens during analysis, as of now, the NoteTag message is
> unambiguous at the point of the tags construction.
The stream error state is designed to store a "superposition" of different
error states. This is part of `evalFseek`:
StateFailed = StateFailed->set<StreamMap>(
StreamSym,
StreamState::getOpened(Desc, ErrorNone | ErrorFEof | ErrorFError, true));
C.addTransition(StateFailed,
constructNoteTag(C, StreamSym,
{&BT_StreamEof, &BT_IndeterminatePosition}));
The code above means the same as this code:
StateFailedFEof = StateFailed->set<StreamMap>(
StreamSym,
StreamState::getOpened(Desc, ErrorFEof, false));
C.addTransition(StateFailedFEof, constructNoteTag(C, StreamSym,
{&BT_StreamEof}));
StateFailedFErrorIndeterminate = StateFailed->set<StreamMap>(
StreamSym,
StreamState::getOpened(Desc, ErrorFError, true));
C.addTransition(StateFailedFErrorIndeterminate, constructNoteTag(C,
StreamSym, {&BT_IndeterminatePosition}));
StateFailedIndeterminate = StateFailed->set<StreamMap>(
StreamSym,
StreamState::getOpened(Desc, ErrorNone, true));
C.addTransition(StateFailedIndeterminate, constructNoteTag(C, StreamSym,
{&BT_IndeterminatePosition}));
In this code the NoteTag message is unambiguous. The code above is a
"compression" of this and at the construction of the NoteTag message is in
"superposition" state too (like the error state that determines the message).
`freopen` is a different case: At failure it returns a NULL pointer and the
stream becomes in an invalid state. But if the return value of `freopen` is not
assigned to it, the stream pointer is not set to NULL:
- `F = freopen(0, "w", F);` F will be NULL at failure, this makes a bug with
`BT_FileNull` bug type.
- `freopen(0, "w", F);` F becomes invalid but not NULL, if used then a
`BT_UseAfterOpenFailed` bug is detected (this is the only case for this bug
type).
At failure of `freopen` we can not tell which case will occur later (it depends
on the analyzed code). (It may be possible to have only one bug for these cases
but a differentation is needed to tell the user if a file was NULL or invalid
but not NULL.)
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D106262/new/
https://reviews.llvm.org/D106262
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