printf: prevent '\0' in format string from truncating outputFRP-3578-g359211429

Commit 4a2af48e6 (printf: emit more contiguous text to improve escape
sequences) didn't treat an escaped null byte in the format string
correctly.  The output string was truncated at the null byte.

Detect this case, output the partial string and the null byte and
carry on.

1 files changed, 9 insertions, 1 deletions

diff --git a/coreutils/printf.c b/coreutils/printf.c
index 45d761d1c..d2b715406 100644
--- a/coreutils/printf.c
+++ b/coreutils/printf.c
@@ -423,7 +423,15 @@ static char **print_formatted(char *f, char **argv, int *conv_err)
                                 printf(s);
                                 return saved_argv; /* causes main() to exit */
                         }
-                        *t++ = bb_process_escape_sequence((const char **)&f);
+                        *t = bb_process_escape_sequence((const char **)&f);
+                        if (*t == '\0') {
+                                printf(s);
+                                bb_putchar(*t);
+                                t = s;
+                        }
+                        else {
+                                ++t;
+                        }
                         f--;
                         break;
                 default: