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Merge "Add EFD_SEMAPHORE flag for eventfd."

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Christopher Ferris 2019-09-03 19:16:55 +00:00 committed by Gerrit Code Review
commit add3a4ae70
2 changed files with 54 additions and 4 deletions
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2
libc/include/sys/eventfd.h
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@ -38,6 +38,8 @@
__BEGIN_DECLS
/** The eventfd() flag to provide semaphore-like semantics for reads. */
#define EFD_SEMAPHORE (1 << 0)
/** The eventfd() flag for a close-on-exec file descriptor. */
#define EFD_CLOEXEC O_CLOEXEC
/** The eventfd() flag for a non-blocking file descriptor. */

56
tests/eventfd_test.cpp
View file

@ -21,14 +21,16 @@
#include <sys/eventfd.h>
#include "utils.h"
TEST(eventfd, smoke) {
unsigned int initial_value = 2;
int fd = eventfd(initial_value, O_NONBLOCK);
ASSERT_NE(fd, -1);
constexpr unsigned int kInitialValue = 2;
int fd = eventfd(kInitialValue, EFD_NONBLOCK);
ASSERT_NE(-1, fd);
eventfd_t value = 123;
ASSERT_EQ(0, eventfd_read(fd, &value));
ASSERT_EQ(initial_value, value);
ASSERT_EQ(kInitialValue, value);
// Reading clears the counter.
ASSERT_EQ(-1, eventfd_read(fd, &value));
@ -44,3 +46,49 @@ TEST(eventfd, smoke) {
close(fd);
}
TEST(eventfd, cloexec) {
constexpr unsigned int kInitialValue = 2;
int fd = eventfd(kInitialValue, EFD_CLOEXEC);
ASSERT_NE(-1, fd);
AssertCloseOnExec(fd, true);
eventfd_t value = 123;
ASSERT_EQ(0, eventfd_read(fd, &value));
ASSERT_EQ(kInitialValue, value);
close(fd);
fd = eventfd(kInitialValue, EFD_NONBLOCK | EFD_CLOEXEC);
ASSERT_NE(-1, fd);
AssertCloseOnExec(fd, true);
value = 123;
ASSERT_EQ(0, eventfd_read(fd, &value));
ASSERT_EQ(kInitialValue, value);
close(fd);
}
TEST(eventfd, semaphore) {
int fd = eventfd(3, EFD_NONBLOCK | EFD_SEMAPHORE);
ASSERT_NE(-1, fd);
eventfd_t value = 123;
ASSERT_EQ(0, eventfd_read(fd, &value));
ASSERT_EQ(1U, value);
value = 123;
ASSERT_EQ(0, eventfd_read(fd, &value));
ASSERT_EQ(1U, value);
value = 123;
ASSERT_EQ(0, eventfd_read(fd, &value));
ASSERT_EQ(1U, value);
// The counter is cleared after the initial value decrements to 0.
ASSERT_EQ(-1, eventfd_read(fd, &value));
ASSERT_EQ(EAGAIN, errno);
close(fd);
}