1 files changed, 9 insertions, 7 deletions

diff --git a/coreutils/echo.c b/coreutils/echo.c
index fd6c950ea..cc9b9e6f4 100644
--- a/coreutils/echo.c
+++ b/coreutils/echo.c
@@ -27,10 +27,8 @@
 
 /* This is a NOFORK applet. Be very careful! */
 
-/* argc is unused, but removing it precludes compiler from
- * using call -> jump optimization */
+/* NB: can be used by shell even if not enabled as applet */
 
-int echo_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int echo_main(int argc ATTRIBUTE_UNUSED, char **argv)
 {
         const char *arg;
@@ -110,15 +108,19 @@ int echo_main(int argc ATTRIBUTE_UNUSED, char **argv)
                                 }
 #if !ENABLE_FEATURE_FANCY_ECHO
                                 /* SUSv3 specifies that octal escapes must begin with '0'. */
-                                if ( (((unsigned char)*arg) - '1') >= 7)
+                                if ( ((int)(unsigned char)(*arg) - '0') >= 8) /* '8' or bigger */
 #endif
                                 {
                                         /* Since SUSv3 mandates a first digit of 0, 4-digit octals
                                         * of the form \0### are accepted. */
-                                        if (*arg == '0' && ((unsigned char)(arg[1]) - '0') < 8) {
-                                                arg++;
+                                        if (*arg == '0') {
+                                                /* NB: don't turn "...\0" into "...\" */
+                                                if (arg[1] && ((unsigned char)(arg[1]) - '0') < 8) {
+                                                        arg++;
+                                                }
                                         }
-                                        /* bb_process_escape_sequence can handle nul correctly */
+                                        /* bb_process_escape_sequence handles NUL correctly
+                                         * ("...\" case). */
                                         c = bb_process_escape_sequence(&arg);
                                 }
                         }