block/noblock commands

2 files changed, 58 insertions, 0 deletions

diff --git a/block.c b/block.c
new file mode 100644
index 0000000..40178d8
--- /dev/null
+++ b/block.c
@@ -0,0 +1,20 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/select.h>
+
+// utility to block until stdin has input
+// public domain
+
+int main(int argc, char *argv[]) {
+	fd_set readset;
+	FD_ZERO(&readset);
+	FD_SET(STDIN_FILENO, &readset);
+	if (select(1, &readset, NULL, NULL, NULL) == -1) {
+		perror(argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	return 0;
+}
diff --git a/noblock.c b/noblock.c
new file mode 100644
index 0000000..d46b736
--- /dev/null
+++ b/noblock.c
@@ -0,0 +1,38 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/select.h>
+
+// utility to read non-blockingly from stdin. 
+// returns exit code 1 on EOF. returns EXIT_FAILURE on error.
+// public domain
+
+int main(int argc, char *argv[]) {
+	long int max_chars = -1;
+	if (argc > 1) max_chars = atoi(argv[1]);
+
+	fd_set readset;
+	FD_ZERO(&readset);
+	FD_SET(STDIN_FILENO, &readset);
+	struct timeval timeout = {0,0};
+	 
+	int result;
+	size_t n = 0;
+	while ((result = select(1, &readset, NULL, NULL, &timeout)) != -1) {
+		if (result == 0) return 0; // there is nothing to read
+
+		int c = getc(stdin);
+		if (c == EOF) {
+			if (feof(stdin)) return 1;
+			else {
+				perror(argv[0]);
+				return EXIT_FAILURE;
+			}
+		} else putc(c, stdout);
+		if (++n == max_chars) return 0;
+	} 
+
+	return 0;
+}