test-tty-read: test utility for previous commits

apps/test-tty-read.c

@@ -0,0 +1,53 @@
+#include <string.h>
+#include <stdio.h>
+#include <termios.h>
+#include <unistd.h>
+#include <signal.h>
+
+struct termios old;
+struct termios new;
+void get_initial_termios(void) {
+	tcgetattr(STDIN_FILENO, &old);
+}
+
+void on_sigusr1(int sig) {
+	fprintf(stderr, "received SIGUSR1\n");
+}
+
+int action = TCSADRAIN;
+
+void set_unbuffered(void) {
+	memcpy(&new,&old,sizeof(struct termios));
+	new.c_iflag &= (~ICRNL) & (~IXON);
+	new.c_lflag &= (~ICANON) & (~ECHO) & (~ISIG);
+#ifdef VLNEXT
+	new.c_cc[VLNEXT] = 0;
+#endif
+	new.c_cc[VMIN] = 2;
+	tcsetattr(STDIN_FILENO, action, &new);
+}
+
+void set_buffered(void) {
+	tcsetattr(STDIN_FILENO, action, &old);
+}
+
+int main(int argc, char * argv[]) {
+
+	if (argc > 1 && !strcmp(argv[1], "flush")) {
+		action = TCSAFLUSH;
+	}
+
+	get_initial_termios();
+	fprintf(stderr, "was VMIN=%d, VTIME=%d\n", old.c_cc[VMIN], old.c_cc[VTIME]);
+	set_unbuffered();
+	fprintf(stderr, "now VMIN=%d, VTIME=%d\n", new.c_cc[VMIN], new.c_cc[VTIME]);
+
+	signal(SIGUSR1, on_sigusr1);
+
+	char buf[4096];
+	ssize_t r = read(STDIN_FILENO, buf, 4096);
+
+	fprintf(stderr, "read=%zd\n", r);
+
+	set_buffered();
+}