1 files changed, 26 insertions, 0 deletions
diff --git a/lib/carefulputc.c b/lib/carefulputc.c
new file mode 100644
index 000000000..932233772
--- /dev/null
+++ b/lib/carefulputc.c
@@ -0,0 +1,26 @@
+/* putc() for use in write and wall (that sometimes are sgid tty) */
+/* Avoid control characters in our locale, and also ASCII control characters.
+   Note that the locale of the recipient is unknown. */
+#include <stdio.h>
+#include <ctype.h>
+#include "carefulputc.h"
+
+#define iso8859x_iscntrl(c) \
+	(((c) & 0x7f) < 0x20 || (c) == 0x7f)
+
+int
+carefulputc(int c, FILE *fp) {
+	int ret;
+
+	if (c == '\007' || c == '\t' || c == '\r' || c == '\n' ||
+	    (!iso8859x_iscntrl(c) && (isprint(c) || isspace(c))))
+		ret = putc(c, fp);
+	else if ((c & 0x80) || !isprint(c^0x40))
+		ret = fprintf(fp, "\\%3o", (unsigned char) c);
+	else {
+		ret = putc('^', fp);
+		if (ret != EOF)
+			ret = putc(c^0x40, fp);
+	}
+	return (ret < 0) ? EOF : 0;
+}