libbb: make index_in_substrings return -1 on ambiguous matches

function                                             old     new   delta
index_in_substrings                                   67      93     +26

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 24 insertions, 7 deletions

diff --git a/libbb/compare_string_array.c b/libbb/compare_string_array.c
index 43c59e8e0..599449fe0 100644
--- a/libbb/compare_string_array.c
+++ b/libbb/compare_string_array.c
@@ -53,19 +53,24 @@ int FAST_FUNC index_in_substr_array(const char *const string_array[], const char
 
 int FAST_FUNC index_in_substrings(const char *strings, const char *key)
 {
-        int len = strlen(key);
+        int matched_idx = -1;
+        const int len = strlen(key);
 
         if (len) {
                 int idx = 0;
                 while (*strings) {
                         if (strncmp(strings, key, len) == 0) {
-                                return idx;
+                                if (strings[len] == '\0')
+                                        return idx; /* exact match */
+                                if (matched_idx >= 0)
+                                        return -1; /* ambiguous match */
+                                matched_idx = idx;
                         }
                         strings += strlen(strings) + 1; /* skip NUL */
                         idx++;
                 }
         }
-        return -1;
+        return matched_idx;
 }
 
 const char* FAST_FUNC nth_string(const char *strings, int n)
@@ -76,3 +81,15 @@ const char* FAST_FUNC nth_string(const char *strings, int n)
         }
         return strings;
 }
+
+#ifdef UNUSED_SO_FAR /* only brctl.c needs it yet */
+/* Returns 0 for no, 1 for yes or a negative value on error.  */
+smallint FAST_FUNC yesno(const char *str)
+{
+        static const char no_yes[] ALIGN1 =
+                "0\0" "off\0" "no\0"
+                "1\0" "on\0" "yes\0";
+        int ret = index_in_substrings(no_yes, str);
+        return ret / 3;
+}
+#endif
diff --git a/networking/brctl.c b/networking/brctl.c
index 023518a26..a36ab45c3 100644
--- a/networking/brctl.c
+++ b/networking/brctl.c
@@ -220,10 +220,10 @@ int brctl_main(int argc UNUSED_PARAM, char **argv)
                 }
 #if ENABLE_FEATURE_BRCTL_FANCY
                 if (key == ARG_stp) { /* stp */
-                        static const char stp_opts[] ALIGN1 =
+                        static const char no_yes[] ALIGN1 =
                                 "0\0" "off\0" "n\0" "no\0"   /* 0 .. 3 */
                                 "1\0" "on\0"  "y\0" "yes\0"; /* 4 .. 7 */
-                        int onoff = index_in_strings(stp_opts, *argv);
+                        int onoff = index_in_strings(no_yes, *argv);
                         if (onoff < 0)
                                 bb_error_msg_and_die(bb_msg_invalid_arg, *argv, applet_name);
                         onoff = (unsigned)onoff / 4;
diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
index 6e8ec3e64..adbcd77ac 100644
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -435,8 +435,8 @@ int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg)
                         }
                         break;
 //              case OPTION_BOOLEAN: {
-//                      static const char noyes[] ALIGN1 = "no\0yes\0";
-//                      buffer[0] = retval = index_in_strings(noyes, val);
+//                      static const char no_yes[] ALIGN1 = "no\0yes\0";
+//                      buffer[0] = retval = index_in_strings(no_yes, val);
 //                      retval++; /* 0 - bad; 1: "no" 2: "yes" */
 //                      break;
 //              }