1//=== ErrnoModeling.h - Tracking value of 'errno'. -----------------*- C++ -*-//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// Defines inter-checker API for using the system value 'errno'.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_CLANG_LIB_STATICANALYZER_CHECKERS_ERRNOMODELING_H
14#define LLVM_CLANG_LIB_STATICANALYZER_CHECKERS_ERRNOMODELING_H
15
16#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
17#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
18#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
19#include <optional>
20
21namespace clang {
22namespace ento {
23namespace errno_modeling {
24
25/// Describe how reads and writes of \c errno are handled by the checker.
26enum ErrnoCheckState : unsigned {
27 /// We do not know anything about 'errno'.
28 /// Read and write is always allowed.
29 Irrelevant = 0,
30
31 /// Value of 'errno' should be checked to find out if a previous function call
32 /// has failed.
33 /// When this state is set \c errno must be read by the program before a next
34 /// standard function call or other overwrite of \c errno follows, otherwise
35 /// a bug report is emitted.
36 MustBeChecked = 1,
37
38 /// Value of 'errno' is not allowed to be read, it can contain an unspecified
39 /// value.
40 /// When this state is set \c errno is not allowed to be read by the program
41 /// until it is overwritten or invalidated.
42 MustNotBeChecked = 2
43};
44
45/// Returns the value of 'errno', if 'errno' was found in the AST.
46std::optional<SVal> getErrnoValue(ProgramStateRef State);
47
48/// Returns the errno check state, \c Errno_Irrelevant if 'errno' was not found
49/// (this is not the only case for that value).
50ErrnoCheckState getErrnoState(ProgramStateRef State);
51
52/// Returns the location that points to the \c MemoryRegion where the 'errno'
53/// value is stored. Returns \c std::nullopt if 'errno' was not found. Otherwise
54/// it always returns a valid memory region in the system global memory space.
55std::optional<Loc> getErrnoLoc(ProgramStateRef State);
56
57/// Set value of 'errno' to any SVal, if possible.
58/// The errno check state is set always when the 'errno' value is set.
59ProgramStateRef setErrnoValue(ProgramStateRef State,
60 const LocationContext *LCtx, SVal Value,
61 ErrnoCheckState EState);
62
63/// Set value of 'errno' to a concrete (signed) integer, if possible.
64/// The errno check state is set always when the 'errno' value is set.
65ProgramStateRef setErrnoValue(ProgramStateRef State, CheckerContext &C,
66 uint64_t Value, ErrnoCheckState EState);
67
68/// Set the errno check state, do not modify the errno value.
69ProgramStateRef setErrnoState(ProgramStateRef State, ErrnoCheckState EState);
70
71/// Clear state of errno (make it irrelevant).
72ProgramStateRef clearErrnoState(ProgramStateRef State);
73
74/// Determine if `Call` is a call to an internal function that returns the
75/// location of `errno` (in environments where errno is accessed this way).
76bool isErrnoLocationCall(const CallEvent &Call);
77
78/// Create a NoteTag that displays the message if the 'errno' memory region is
79/// marked as interesting, and resets the interestingness.
80const NoteTag *getErrnoNoteTag(CheckerContext &C, const std::string &Message);
81
82/// Set errno state for the common case when a standard function is successful.
83/// Set \c ErrnoCheckState to \c MustNotBeChecked (the \c errno value is not
84/// affected).
85ProgramStateRef setErrnoForStdSuccess(ProgramStateRef State, CheckerContext &C);
86
87/// Set errno state for the common case when a standard function fails.
88/// Set \c errno value to be not equal to zero and \c ErrnoCheckState to
89/// \c Irrelevant . The irrelevant errno state ensures that no related bug
90/// report is emitted later and no note tag is needed.
91/// \arg \c ErrnoSym Value to be used for \c errno and constrained to be
92/// non-zero.
93ProgramStateRef setErrnoForStdFailure(ProgramStateRef State, CheckerContext &C,
94 NonLoc ErrnoSym);
95
96/// Set errno state for the common case when a standard function indicates
97/// failure only by \c errno. Sets \c ErrnoCheckState to \c MustBeChecked, and
98/// invalidates the errno region (clear of previous value).
99/// \arg \c Elem CFG Element that causes invalidation of \c errno.
100ProgramStateRef setErrnoStdMustBeChecked(ProgramStateRef State,
101 CheckerContext &C,
102 ConstCFGElementRef Elem);
103
104} // namespace errno_modeling
105} // namespace ento
106} // namespace clang
107
108#endif // LLVM_CLANG_LIB_STATICANALYZER_CHECKERS_ERRNOMODELING_H
109