printf: short-circuit output when argument to %b includes \c

printf wasn't correctly handling \c in an argument to the %b format
specifier.

   printf %bXX OK\\c

returned 'OK\cXX' rather than the expected 'OK'.

function                                             old     new   delta
printf_main                                          886     899     +13

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/coreutils/printf.c b/coreutils/printf.c
index 3dd43a978..9ee7350d0 100644
--- a/coreutils/printf.c
+++ b/coreutils/printf.c
@@ -131,8 +131,8 @@ static double my_xstrtod(const char *arg)
         return result;
 }
 
-/* Handles %b */
-static void print_esc_string(const char *str)
+/* Handles %b; return 1 if output is to be short-circuited by \c */
+static int print_esc_string(const char *str)
 {
         char c;
         while ((c = *str) != '\0') {
@@ -145,6 +145,9 @@ static void print_esc_string(const char *str)
                                         str++;
                                 }
                         }
+                        else if (*str == 'c') {
+                                return 1;
+                        }
                         {
                                 /* optimization: don't force arg to be on-stack,
                                  * use another variable for that. */
@@ -155,6 +158,8 @@ static void print_esc_string(const char *str)
                 }
                 putchar(c);
         }
+
+        return 0;
 }
 
 static void print_direc(char *format, unsigned fmt_length,
@@ -280,7 +285,8 @@ static char **print_formatted(char *f, char **argv, int *conv_err)
                         }
                         if (*f == 'b') {
                                 if (*argv) {
-                                        print_esc_string(*argv);
+                                        if (print_esc_string(*argv))
+                                                return saved_argv; /* causes main() to exit */
                                         ++argv;
                                 }
                                 break;