split tty specific stuff out to tty.c

1 files changed, 78 insertions, 0 deletions

diff --git a/tty.c b/tty.c
new file mode 100644
index 0000000..375601c
--- /dev/null
+++ b/tty.c
@@ -0,0 +1,78 @@
+#define _XOPEN_SOURCE 700
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include "more.h"
+
+static FILE *resetty = NULL;
+static struct termios resettings = { 0 };
+
+static void resetterm(void)
+{
+	tcsetattr(fileno(resetty), TCSANOW, &resettings);
+}
+
+static int query_term(const char *cap, const char *variable, int def)
+{
+	int n = 0;
+	char cmd[64];
+	snprintf(cmd, sizeof(cmd), "tput %s", cap);
+	FILE *f = popen(cmd, "r");
+	if (f) {
+		if (fscanf(f, "%d", &n) != 1) {
+			n = 0;
+		}
+		pclose(f);
+		if (n != 0) {
+			return n;
+		}
+	}
+
+	char *value = getenv(variable);
+	if (value) {
+		n = atoi(value);
+	}
+	return n ? n : def;
+}
+
+struct more_tty more_open_tty(int lines)
+{
+	struct more_tty mt = {
+		.tty = stderr,
+		.lines = query_term("lines", "LINES", 24),
+		.columns = query_term("cols", "COLUMNS", 80),
+	};
+
+	if (lines > 0) {
+		mt.lines = lines;
+	}
+
+	/* leave room for prompts */
+	lines--;
+
+	/* FIXME: only open /dev/tty if stderr is not readable */
+	// if (!(fcntl(fileno(mt.tty), F_GETFL) & (O_WRONLY | O_RDWR))) {
+		mt.tty = fopen("/dev/tty", "rb+");
+	// }
+	if (mt.tty == NULL) {
+		perror("Couldn't open tty for reading");
+		exit(1);
+	}
+
+	setbuf(mt.tty, NULL);
+
+	tcgetattr(fileno(mt.tty), &resettings);
+	struct termios term = resettings;
+	term.c_lflag &= ~(ECHO | ICANON);
+	term.c_cc[VMIN] = 1;
+	term.c_cc[VTIME] = 0;
+	tcsetattr(fileno(mt.tty), TCSANOW, &term);
+
+	resetty = mt.tty;
+	atexit(resetterm);
+
+	return mt;
+}