Idlestat: Prevent printing control character in error message

The error message printed out by bad_filename() contains the illegal
character detected. In case the character is not printable,
display the hexadecimal code for it instead of writing out the literal
character as is.

Signed-off-by: Tuukka Tikkanen <tuukka.tikkanen@linaro.org>

Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/idlestat.c b/idlestat.c
index 47f975e..cf6a1e9 100644
--- a/idlestat.c
+++ b/idlestat.c
@@ -36,6 +36,7 @@
 #include <sys/resource.h>
 #include <sys/wait.h>
 #include <assert.h>
+#include <ctype.h>
 
 #include "idlestat.h"
 #include "utils.h"
@@ -67,7 +68,11 @@ static inline int bad_filename(const char *filename)
 	for (; *c; c++) {
 		/* Check for control chars and other bad characters */
 		if (*c < 32 || *c == '<' || *c == '>' || *c == '|') {
-			fprintf(stderr, "Bad character '%c' found in filename\n", *c);
+			fprintf(stderr,
+				isprint(*c) ?
+				"Bad character '%c' found in filename\n" :
+				"Bad character 0x%02x found in filename\n",
+				*c);
 			return EINVAL;
 		}
 	}