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[analyzer][StdLibraryFunctionsChecker] Make close and mmap to accept -1 as fd 

close:
It is quite often that users chose to call close even if the fd is
negative. Theoretically, it would be nicer to close only valid fds, but
in practice the implementations of close just returns with EBADF in case
of a non-valid fd param. So, we can eliminate many false positives if we
let close to take -1 as an fd. Other negative values are very unlikely,
because open and other fd factories return with -1 in case of failure.

mmap:
In the case of MAP_ANONYMOUS flag (which is supported e.g. in Linux) the
mapping is not backed by any file; its contents are initialized to zero.
The fd argument is ignored; however, some implementations require fd to
be -1 if MAP_ANONYMOUS (or MAP_ANON) is specified, and portable
applications should ensure this.
Consequently, we must allow -1 as the 4th arg.

Differential Revision: https://reviews.llvm.org/D92764
This commit is contained in:
Gabor Marton 2020-12-07 16:10:40 +01:00
parent 1dd24e6ab7
commit d14c631673
1 changed files with 3 additions and 3 deletions
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6
clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
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@ -1672,7 +1672,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
addToFunctionSummaryMap("close", Signature(ArgTypes{IntTy}, RetType{IntTy}),
Summary(NoEvalCall)
.ArgConstraint(ArgumentCondition(
0, WithinRange, Range(0, IntMax))));
0, WithinRange, Range(-1, IntMax))));
// long fpathconf(int fildes, int name);
addToFunctionSummaryMap("fpathconf",
@ -1734,7 +1734,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.ArgConstraint(ArgumentCondition(1, WithinRange, Range(1, SizeMax)))
.ArgConstraint(
ArgumentCondition(4, WithinRange, Range(0, IntMax))));
ArgumentCondition(4, WithinRange, Range(-1, IntMax))));
Optional<QualType> Off64_tTy = lookupTy("off64_t");
// void *mmap64(void *addr, size_t length, int prot, int flags, int fd,
@ -1746,7 +1746,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.ArgConstraint(ArgumentCondition(1, WithinRange, Range(1, SizeMax)))
.ArgConstraint(
ArgumentCondition(4, WithinRange, Range(0, IntMax))));
ArgumentCondition(4, WithinRange, Range(-1, IntMax))));
// int pipe(int fildes[2]);
addToFunctionSummaryMap(