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Reapply "[libc] Return errno from OFD failure paths in fcntl." (#166658) #166846

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Merged
merged 5 commits into from
Nov 10, 2025
Merged

Reapply "[libc] Return errno from OFD failure paths in fcntl." (#166658) #166846

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40a8a2b
Reapply "[libc] Return errno from OFD failure paths in fcntl." (#166658)
jtstogel Nov 5, 2025
86f4811
Pass a struct flock into fcntl F_OFD_GETLK.
jtstogel Nov 6, 2025
526e6ab
Merge branch 'main' into refix-fnctl
jtstogel Nov 6, 2025
af9df0c
Fix typo.
jtstogel Nov 6, 2025
ca1a3e9
Remove unnecessary struct qualifier.
jtstogel Nov 10, 2025
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2 changes: 1 addition & 1 deletion libc/src/__support/OSUtil/linux/fcntl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -66,7 +66,7 @@ ErrorOr<int> fcntl(int fd, int cmd, void *arg) {
LIBC_NAMESPACE::syscall_impl<int>(FCNTL_SYSCALL_ID, fd, cmd, &flk64);
// On failure, return
if (ret < 0)
return Error(-1);
return Error(-ret);
// Check for overflow, i.e. the offsets are not the same when cast
// to off_t from off64_t.
if (static_cast<off_t>(flk64.l_len) != flk64.l_len ||
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161 changes: 99 additions & 62 deletions libc/test/src/fcntl/fcntl_test.cpp
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Expand Up @@ -94,68 +94,105 @@ TEST_F(LlvmLibcFcntlTest, FcntlSetFl) {
ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds(0));
}

TEST_F(LlvmLibcFcntlTest, FcntlGetLkRead) {
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
constexpr const char *TEST_FILE_NAME = "testdata/fcntl_getlkread.test";
auto TEST_FILE = libc_make_test_file_path(TEST_FILE_NAME);

struct flock flk, svflk;
int retVal;
int fd =
LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_TRUNC | O_RDONLY, S_IRWXU);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(fd, 0);

flk.l_type = F_RDLCK;
flk.l_start = 0;
flk.l_whence = SEEK_SET;
flk.l_len = 50;

// copy flk into svflk
svflk = flk;

retVal = LIBC_NAMESPACE::fcntl(fd, F_GETLK, &svflk);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(retVal, -1);
ASSERT_NE((int)flk.l_type, F_WRLCK); // File should not be write locked.

retVal = LIBC_NAMESPACE::fcntl(fd, F_SETLK, &svflk);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(retVal, -1);

ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds(0));
}

TEST_F(LlvmLibcFcntlTest, FcntlGetLkWrite) {
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
constexpr const char *TEST_FILE_NAME = "testdata/fcntl_getlkwrite.test";
auto TEST_FILE = libc_make_test_file_path(TEST_FILE_NAME);

struct flock flk, svflk;
int retVal;
int fd = LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_TRUNC | O_RDWR, S_IRWXU);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(fd, 0);

flk.l_type = F_WRLCK;
flk.l_start = 0;
flk.l_whence = SEEK_SET;
flk.l_len = 0;

// copy flk into svflk
svflk = flk;

retVal = LIBC_NAMESPACE::fcntl(fd, F_GETLK, &svflk);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(retVal, -1);
ASSERT_NE((int)flk.l_type, F_RDLCK); // File should not be read locked.

retVal = LIBC_NAMESPACE::fcntl(fd, F_SETLK, &svflk);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(retVal, -1);

ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds(0));
}
/* Tests that are common between OFD and traditional variants of fcntl locks. */
template <int GETLK_CMD, int SETLK_CMD>
class LibcFcntlCommonLockTests : public LlvmLibcFcntlTest {
public:
void GetLkRead() {
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
constexpr const char *TEST_FILE_NAME = "testdata/fcntl_getlkread.test";
const auto TEST_FILE = libc_make_test_file_path(TEST_FILE_NAME);

struct flock flk = {};
struct flock svflk = {};
int retVal;
int fd =
LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_TRUNC | O_RDONLY, S_IRWXU);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(fd, 0);

flk.l_type = F_RDLCK;
flk.l_start = 0;
flk.l_whence = SEEK_SET;
flk.l_len = 50;

// copy flk into svflk
svflk = flk;

retVal = LIBC_NAMESPACE::fcntl(fd, GETLK_CMD, &svflk);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(retVal, -1);
ASSERT_NE((int)svflk.l_type, F_WRLCK); // File should not be write locked.

retVal = LIBC_NAMESPACE::fcntl(fd, SETLK_CMD, &svflk);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(retVal, -1);

ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds(0));
}

void GetLkWrite() {
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
constexpr const char *TEST_FILE_NAME = "testdata/fcntl_getlkwrite.test";
const auto TEST_FILE = libc_make_test_file_path(TEST_FILE_NAME);

struct flock flk = {};
struct flock svflk = {};
int retVal;
int fd =
LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_TRUNC | O_RDWR, S_IRWXU);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(fd, 0);

flk.l_type = F_WRLCK;
flk.l_start = 0;
flk.l_whence = SEEK_SET;
flk.l_len = 0;

// copy flk into svflk
svflk = flk;

retVal = LIBC_NAMESPACE::fcntl(fd, GETLK_CMD, &svflk);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(retVal, -1);
ASSERT_NE((int)svflk.l_type, F_RDLCK); // File should not be read locked.

retVal = LIBC_NAMESPACE::fcntl(fd, SETLK_CMD, &svflk);
ASSERT_ERRNO_SUCCESS();
ASSERT_GT(retVal, -1);

ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds(0));
}

void UseAfterClose() {
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
constexpr const char *TEST_FILE_NAME =
"testdata/fcntl_use_after_close.test";
const auto TEST_FILE = libc_make_test_file_path(TEST_FILE_NAME);
int fd =
LIBC_NAMESPACE::open(TEST_FILE, O_CREAT | O_TRUNC | O_RDWR, S_IRWXU);
ASSERT_THAT(LIBC_NAMESPACE::close(fd), Succeeds(0));

struct flock flk = {};
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@lntue lntue Nov 9, 2025

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Nit: remove struct if there is no name conflict.

flk.l_type = F_RDLCK;
flk.l_start = 0;
flk.l_whence = SEEK_SET;
flk.l_len = 50;
ASSERT_EQ(-1, LIBC_NAMESPACE::fcntl(fd, GETLK_CMD, &flk));
ASSERT_ERRNO_EQ(EBADF);
}
};

#define COMMON_LOCK_TESTS(NAME, GETLK_CMD, SETLK_CMD) \
using NAME = LibcFcntlCommonLockTests<GETLK_CMD, GETLK_CMD>; \
TEST_F(NAME, GetLkRead) { GetLkRead(); } \
TEST_F(NAME, GetLkWrite) { GetLkWrite(); } \
TEST_F(NAME, UseAfterClose) { UseAfterClose(); } \
static_assert(true, "Require semicolon.")

COMMON_LOCK_TESTS(LlvmLibcFcntlProcessAssociatedLockTest, F_GETLK, F_SETLK);
COMMON_LOCK_TESTS(LlvmLibcFcntlOpenFileDescriptionLockTest, F_OFD_GETLK,
F_OFD_SETLK);

TEST_F(LlvmLibcFcntlTest, UseAfterClose) {
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
Expand Down