Add EFD_SEMAPHORE flag for eventfd.
Add a test for the new flag and add a test for the EFD_CLOEXEC flag.
Test: New unit tests pass on glibc and target.
Change-Id: Ib7a6ea4aadbd67ba8a523b6114a49fb8d6a43f12
diff --git a/libc/include/sys/eventfd.h b/libc/include/sys/eventfd.h
index 85f9877..1b6ad29 100644
--- a/libc/include/sys/eventfd.h
+++ b/libc/include/sys/eventfd.h
@@ -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. */
diff --git a/tests/eventfd_test.cpp b/tests/eventfd_test.cpp
index 68d9192..3c303c2 100644
--- a/tests/eventfd_test.cpp
+++ b/tests/eventfd_test.cpp
@@ -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 @@
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);
+}