On server, channel dprint through the readline-device. Also some refactors and quality improvements.

luprex/cpp/drv/drvutil-linux.cpp

@@ -0,0 +1,83 @@
+
+#include <time.h>
+#include <string>
+#include <cstring>
+#include <cassert>
+#include <cstdio>
+#include <pthread.h>
+
+namespace drvutil {
+
+// strerror has to be the most overcomplicated function imaginable. The simple
+// version, 'strerror', is not thread-safe, and the improved versions are all
+// incompatible from OS to OS.  Even different versions of linux aren't
+// compatible.  A lot of conditional compilation is needed.
+
+inline static void strerror_helper(int status, int errnum, char errbuf[256]) {
+    if (status != 0) {
+        snprintf(errbuf, 256, "unknown errno %d", errnum);
+    }
+}
+
+inline static void strerror_helper(const char *result, int errnum, char errbuf[256]) {
+    if (result != errbuf) {
+        snprintf(errbuf, 256, "%s", result);
+    }
+}
+
+void strerror_safe(int errnum, char errbuf[256]) {
+    auto rval = strerror_r(errnum, errbuf, 256);
+    strerror_helper(rval, errnum, errbuf);
+}
+
+std::string strerror_str(int errnum) {
+    char buf[256];
+    strerror_safe(errnum, buf);
+    return buf;
+}
+
+
+
+
+class MonoClock {
+private:
+    struct timespec base_;
+public:
+    MonoClock() {
+        int status = clock_gettime(CLOCK_MONOTONIC, &base_);
+        assert(status == 0);
+    }
+    double get() {
+        struct timespec t;
+        int status = clock_gettime(CLOCK_MONOTONIC, &t);
+        assert(status == 0);
+        double tv_sec = t.tv_sec - base_.tv_sec;
+        double tv_nsec = t.tv_nsec - base_.tv_nsec;
+        return tv_sec + (tv_nsec * 1.0E-9);
+    }
+};
+
+static MonoClock monoclock;
+double get_monotonic_clock() {
+    return monoclock.get();
+}
+
+
+void console_write(const std::u32string &cps) {
+    std::string utf8 = drvutil::utf32_to_utf8(cps);
+    write(1, utf8.c_str(), utf8.size());
+}
+
+std::u32string console_read() {
+    std::u32string result;
+    char buffer[512];
+    int nread = read(0, buffer, 512);
+    if (nread > 0) {
+        std::string_view s(buffer, nread);
+        result = drvutil::utf8_to_utf32(s, nullptr);
+    }
+    return result;
+}
+
+} // namespace drvutil
+