[clang] 258c9be - [clang][analyzer] Handle special value AT_FDCWD in affected standard functions
Balázs Kéri via cfe-commits
cfe-commits at lists.llvm.org
Tue May 16 00:29:03 PDT 2023
Author: Balázs Kéri
Date: 2023-05-16T09:28:14+02:00
New Revision: 258c9bebbdfa793493b71db555f5deb5ade499b4
URL: https://github.com/llvm/llvm-project/commit/258c9bebbdfa793493b71db555f5deb5ade499b4
DIFF: https://github.com/llvm/llvm-project/commit/258c9bebbdfa793493b71db555f5deb5ade499b4.diff
LOG: [clang][analyzer] Handle special value AT_FDCWD in affected standard functions
Some file and directory related functions have an integer file descriptor argument
that can be a valid file descriptor or a special value AT_FDCWD. This value is
relatively often used in open source projects and is usually defined as a negative
number, and the checker reports false warnings (a valid file descriptor is not
negative) if this fix is not included.
Reviewed By: steakhal
Differential Revision: https://reviews.llvm.org/D149160
Added:
Modified:
clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
clang/test/Analysis/std-c-library-functions-arg-constraints.c
Removed:
################################################################################
diff --git a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
index 4e3ea0934b6f1..ef85d60c658ec 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
@@ -1392,6 +1392,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
SValBuilder &SVB = C.getSValBuilder();
BasicValueFactory &BVF = SVB.getBasicValueFactory();
const ASTContext &ACtx = BVF.getContext();
+ Preprocessor &PP = C.getPreprocessor();
// Helper class to lookup a type by its name.
class LookupType {
@@ -1527,14 +1528,11 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
const RangeInt UCharRangeMax =
std::min(BVF.getMaxValue(ACtx.UnsignedCharTy).getLimitedValue(), IntMax);
- // The platform dependent value of EOF.
- // Try our best to parse this from the Preprocessor, otherwise fallback to -1.
- const auto EOFv = [&C]() -> RangeInt {
- if (const std::optional<int> OptInt =
- tryExpandAsInteger("EOF", C.getPreprocessor()))
- return *OptInt;
- return -1;
- }();
+ // Get platform dependent values of some macros.
+ // Try our best to parse this from the Preprocessor, otherwise fallback to a
+ // default value (what is found in a library header).
+ const auto EOFv = tryExpandAsInteger("EOF", PP).value_or(-1);
+ const auto AT_FDCWDv = tryExpandAsInteger("AT_FDCWD", PP).value_or(-100);
// Auxiliary class to aid adding summaries to the summary map.
struct AddToFunctionSummaryMap {
@@ -1979,6 +1977,12 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
ConstraintSet{ReturnValueCondition(WithinRange, Range(-1, IntMax))};
const auto &ReturnsValidFileDescriptor = ReturnsNonnegative;
+ auto ValidFileDescriptorOrAtFdcwd = [&](ArgNo ArgN) {
+ return std::make_shared<RangeConstraint>(
+ ArgN, WithinRange, Range({AT_FDCWDv, AT_FDCWDv}, {0, IntMax}),
+ "a valid file descriptor or AT_FDCWD");
+ };
+
// FILE *fopen(const char *restrict pathname, const char *restrict mode);
addToFunctionSummaryMap(
"fopen",
@@ -2130,6 +2134,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.Case(ReturnsZero, ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(0)))
.ArgConstraint(NotNull(ArgNo(1))));
// int dup(int fildes);
@@ -2207,7 +2212,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
.Case(ReturnsZero, ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
.ArgConstraint(NotNull(ArgNo(0)))
- .ArgConstraint(ArgumentCondition(1, WithinRange, Range(0, IntMax)))
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(1)))
.ArgConstraint(NotNull(ArgNo(2))));
// int lockf(int fd, int cmd, off_t len);
@@ -2318,6 +2323,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.Case(ReturnsZero, ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(0)))
.ArgConstraint(NotNull(ArgNo(1))));
std::optional<QualType> Dev_tTy = lookupTy("dev_t");
@@ -2339,6 +2345,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.Case(ReturnsZero, ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(0)))
.ArgConstraint(NotNull(ArgNo(1))));
// int chmod(const char *path, mode_t mode);
@@ -2357,7 +2364,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.Case(ReturnsZero, ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
- .ArgConstraint(ArgumentCondition(0, WithinRange, Range(0, IntMax)))
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(0)))
.ArgConstraint(NotNull(ArgNo(1))));
// int fchmod(int fildes, mode_t mode);
@@ -2381,7 +2388,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.Case(ReturnsZero, ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
- .ArgConstraint(ArgumentCondition(0, WithinRange, Range(0, IntMax)))
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(0)))
.ArgConstraint(NotNull(ArgNo(1))));
// int chown(const char *path, uid_t owner, gid_t group);
@@ -2446,9 +2453,9 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.Case(ReturnsZero, ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
- .ArgConstraint(ArgumentCondition(0, WithinRange, Range(0, IntMax)))
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(0)))
.ArgConstraint(NotNull(ArgNo(1)))
- .ArgConstraint(ArgumentCondition(2, WithinRange, Range(0, IntMax)))
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(2)))
.ArgConstraint(NotNull(ArgNo(3))));
// int unlink(const char *pathname);
@@ -2466,7 +2473,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.Case(ReturnsZero, ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
- .ArgConstraint(ArgumentCondition(0, WithinRange, Range(0, IntMax)))
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(0)))
.ArgConstraint(NotNull(ArgNo(1))));
std::optional<QualType> StructStatTy = lookupTy("stat");
@@ -2515,7 +2522,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.Case(ReturnsZero, ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
- .ArgConstraint(ArgumentCondition(0, WithinRange, Range(0, IntMax)))
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(0)))
.ArgConstraint(NotNull(ArgNo(1)))
.ArgConstraint(NotNull(ArgNo(2))));
@@ -2690,7 +2697,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
ReturnValueCondition(WithinRange, Range(0, Ssize_tMax))},
ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
- .ArgConstraint(ArgumentCondition(0, WithinRange, Range(0, IntMax)))
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(0)))
.ArgConstraint(NotNull(ArgNo(1)))
.ArgConstraint(NotNull(ArgNo(2)))
.ArgConstraint(BufferSize(/*Buffer=*/ArgNo(2),
@@ -2707,7 +2714,9 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.Case(ReturnsZero, ErrnoMustNotBeChecked)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant)
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(0)))
.ArgConstraint(NotNull(ArgNo(1)))
+ .ArgConstraint(ValidFileDescriptorOrAtFdcwd(ArgNo(2)))
.ArgConstraint(NotNull(ArgNo(3))));
// char *realpath(const char *restrict file_name,
diff --git a/clang/test/Analysis/std-c-library-functions-arg-constraints.c b/clang/test/Analysis/std-c-library-functions-arg-constraints.c
index 1d9e3ae688cc7..981318c755e1e 100644
--- a/clang/test/Analysis/std-c-library-functions-arg-constraints.c
+++ b/clang/test/Analysis/std-c-library-functions-arg-constraints.c
@@ -3,6 +3,7 @@
// RUN: -analyzer-checker=core \
// RUN: -analyzer-checker=apiModeling.StdCLibraryFunctions \
// RUN: -analyzer-checker=alpha.unix.StdCLibraryFunctionArgs \
+// RUN: -analyzer-config apiModeling.StdCLibraryFunctions:ModelPOSIX=true \
// RUN: -analyzer-checker=debug.StdCLibraryFunctionsTester \
// RUN: -analyzer-checker=debug.ExprInspection \
// RUN: -triple x86_64-unknown-linux-gnu \
@@ -13,6 +14,7 @@
// RUN: -analyzer-checker=core \
// RUN: -analyzer-checker=apiModeling.StdCLibraryFunctions \
// RUN: -analyzer-checker=alpha.unix.StdCLibraryFunctionArgs \
+// RUN: -analyzer-config apiModeling.StdCLibraryFunctions:ModelPOSIX=true \
// RUN: -analyzer-checker=debug.StdCLibraryFunctionsTester \
// RUN: -analyzer-checker=debug.ExprInspection \
// RUN: -triple x86_64-unknown-linux-gnu \
@@ -309,3 +311,26 @@ void test_min_buf_size(void) {
// bugpath-warning{{The 1st argument to '__buf_size_arg_constraint_concrete' is out of the accepted range; It should be a buffer with size equal to or greater than 10}} \
// bugpath-note{{The 1st argument to '__buf_size_arg_constraint_concrete' is out of the accepted range; It should be a buffer with size equal to or greater than 10}}
}
+
+void test_file_fd_at_functions() {
+ (void)linkat(-22, "from", AT_FDCWD, "to", 0); // \
+ // report-warning{{The 1st argument to 'linkat' is -22 but should be a valid file descriptor or AT_FDCWD}} \
+ // bugpath-warning{{The 1st argument to 'linkat' is -22 but should be a valid file descriptor or AT_FDCWD}} \
+ // bugpath-note{{The 1st argument to 'linkat' is -22 but should be a valid file descriptor or AT_FDCWD}}
+
+ // no warning for these functions if the AT_FDCWD value is used
+ (void)linkat(AT_FDCWD, "from", AT_FDCWD, "to", 0);
+ (void)faccessat(AT_FDCWD, "path", 0, 0);
+ (void)symlinkat("oldpath", AT_FDCWD, "newpath");
+ (void)mkdirat(AT_FDCWD, "path", 0);
+ (void)mknodat(AT_FDCWD, "path", 0, 0);
+ (void)fchmodat(AT_FDCWD, "path", 0, 0);
+ (void)fchownat(AT_FDCWD, "path", 0, 0, 0);
+ (void)linkat(AT_FDCWD, "oldpath", AT_FDCWD, "newpath", 0);
+ (void)unlinkat(AT_FDCWD, "newpath", 0);
+ struct stat St;
+ (void)fstatat(AT_FDCWD, "newpath", &St, 0);
+ char Buf[10];
+ (void)readlinkat(AT_FDCWD, "newpath", Buf, 10);
+ (void)renameat(AT_FDCWD, "oldpath", AT_FDCWD, "newpath");
+}
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