Add a wrapper for signalfd
The wrapper blocks (and unblock) signals for the thread as well.
This will get tested by the wakeup for the IPC.
Change-Id: Ica701034e8890fc0689b8528b4d7448fd630ed64
diff --git a/aos/ipc_lib/BUILD b/aos/ipc_lib/BUILD
index 03a4752..85f6dcd 100644
--- a/aos/ipc_lib/BUILD
+++ b/aos/ipc_lib/BUILD
@@ -148,3 +148,16 @@
"@com_github_gflags_gflags//:gflags",
],
)
+
+cc_library(
+ name = "signalfd",
+ srcs = [
+ "signalfd.cc",
+ ],
+ hdrs = [
+ "signalfd.h",
+ ],
+ deps = [
+ "//aos/logging",
+ ],
+)
diff --git a/aos/ipc_lib/signalfd.cc b/aos/ipc_lib/signalfd.cc
new file mode 100644
index 0000000..1679b46
--- /dev/null
+++ b/aos/ipc_lib/signalfd.cc
@@ -0,0 +1,47 @@
+#include "aos/ipc_lib/signalfd.h"
+
+#include <signal.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <initializer_list>
+
+#include "aos/logging/logging.h"
+
+namespace aos {
+namespace ipc_lib {
+
+SignalFd::SignalFd(::std::initializer_list<int> signals) {
+ // Build up the mask with the provided signals.
+ sigemptyset(&mask_);
+ for (int signal : signals) {
+ sigaddset(&mask_, signal);
+ }
+ // Then build a signalfd. Make it nonblocking so it works well with an epoll
+ // loop, and have it close on exec.
+ PCHECK(fd_ = signalfd(-1, &mask_, SFD_NONBLOCK | SFD_CLOEXEC));
+ // Now that we have a consumer of the signal, block the signals so the
+ // signalfd gets them.
+ pthread_sigmask(SIG_BLOCK, &mask_, nullptr);
+}
+
+SignalFd::~SignalFd() {
+ // Unwind the constructor. Unblock the signals and close the fd.
+ pthread_sigmask(SIG_UNBLOCK, &mask_, nullptr);
+ PCHECK(close(fd_));
+}
+
+signalfd_siginfo SignalFd::Read() {
+ signalfd_siginfo result;
+
+ const int ret =
+ read(fd_, static_cast<void *>(&result), sizeof(signalfd_siginfo));
+ // If we didn't get the right amount of data, signal that there was a problem
+ // by setting the signal number to 0.
+ if (ret != static_cast<int>(sizeof(signalfd_siginfo))) {
+ result.ssi_signo = 0;
+ }
+ return result;
+}
+
+} // namespace ipc_lib
+} // namespace aos
diff --git a/aos/ipc_lib/signalfd.h b/aos/ipc_lib/signalfd.h
new file mode 100644
index 0000000..a545a80
--- /dev/null
+++ b/aos/ipc_lib/signalfd.h
@@ -0,0 +1,38 @@
+#ifndef AOS_IPC_LIB_SIGNALFD_H_
+#define AOS_IPC_LIB_SIGNALFD_H_
+
+#include <sys/signalfd.h>
+#include <sys/types.h>
+#include <initializer_list>
+
+namespace aos {
+namespace ipc_lib {
+
+// Class to manage a signalfd.
+class SignalFd {
+ public:
+ // Constructs a SignalFd for the provided list of signals.
+ // Blocks the signals at the same time in this thread.
+ SignalFd(::std::initializer_list<int> signals);
+
+ SignalFd(const SignalFd &) = delete;
+ SignalFd &operator=(const SignalFd &) = delete;
+ ~SignalFd();
+
+ // Returns the file descriptor for the signalfd.
+ int fd() { return fd_; }
+
+ // Reads a signalfd_siginfo. If there was an error, the resulting ssi_signo
+ // will be 0.
+ signalfd_siginfo Read();
+
+ private:
+ int fd_ = -1;
+
+ sigset_t mask_;
+};
+
+} // namespace ipc_lib
+} // namespace aos
+
+#endif // AOS_IPC_LIB_SIGNALFD_H_