int read_with_timeout(int fd, char *buf, size_t count, long usec)
As a regular read(2), but allows to specify a timeout in
micro-seconds. Returns -EAGAIN on timeout.
Implemented using select().
Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
---
tools/testing/selftests/bpf/Makefile | 1 +
tools/testing/selftests/bpf/io_helpers.c | 21 +++++++++++++++++++++
tools/testing/selftests/bpf/io_helpers.h | 7 +++++++
3 files changed, 29 insertions(+)
create mode 100644 tools/testing/selftests/bpf/io_helpers.c
create mode 100644 tools/testing/selftests/bpf/io_helpers.h
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index edef5df08cb2..b1080284522d 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -742,6 +742,7 @@ TRUNNER_EXTRA_SOURCES := test_progs.c \
unpriv_helpers.c \
netlink_helpers.c \
jit_disasm_helpers.c \
+ io_helpers.c \
test_loader.c \
xsk.c \
disasm.c \
diff --git a/tools/testing/selftests/bpf/io_helpers.c b/tools/testing/selftests/bpf/io_helpers.c
new file mode 100644
index 000000000000..4ada0a74aa1f
--- /dev/null
+++ b/tools/testing/selftests/bpf/io_helpers.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <sys/select.h>
+#include <unistd.h>
+#include <errno.h>
+
+int read_with_timeout(int fd, char *buf, size_t count, long usec)
+{
+ const long M = 1000 * 1000;
+ struct timeval tv = { usec / M, usec % M };
+ fd_set fds;
+ int err;
+
+ FD_ZERO(&fds);
+ FD_SET(fd, &fds);
+ err = select(fd + 1, &fds, NULL, NULL, &tv);
+ if (err < 0)
+ return err;
+ if (FD_ISSET(fd, &fds))
+ return read(fd, buf, count);
+ return -EAGAIN;
+}
diff --git a/tools/testing/selftests/bpf/io_helpers.h b/tools/testing/selftests/bpf/io_helpers.h
new file mode 100644
index 000000000000..21e1134cd3ce
--- /dev/null
+++ b/tools/testing/selftests/bpf/io_helpers.h
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <unistd.h>
+
+/* As a regular read(2), but allows to specify a timeout in micro-seconds.
+ * Returns -EAGAIN on timeout.
+ */
+int read_with_timeout(int fd, char *buf, size_t count, long usec);
--
2.47.0
