strrchr: bikeshed painting time!

 replace cubic running time implementation with quadratic
 make embedded test actually readable

function                                             old     new   delta
strrstr                                               42      44      +2

1 files changed, 43 insertions, 51 deletions

diff --git a/libbb/strrstr.c b/libbb/strrstr.c
index 126fed75c..088d9f457 100644
--- a/libbb/strrstr.c
+++ b/libbb/strrstr.c
@@ -7,73 +7,65 @@
  * Licensed under GPLv2 or later, see file License in this tarball for details.
  */
 
+#ifdef __DO_STRRSTR_TEST
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#else
 #include "libbb.h"
+#endif
 
 /*
  * The strrstr() function finds the last occurrence of the substring needle
  * in the string haystack. The terminating nul characters are not compared.
  */
-char *strrstr(const char *haystack, const char *needle)
+char* strrstr(const char *haystack, const char *needle)
 {
         char *r = NULL;
-        
-        do {
+
+        if (!needle[0])
+                return (char*)haystack;
+        while (1) {
                 char *p = strstr(haystack, needle);
-                if (p)
-                        r = p;
-        } while (*haystack++);
-        return r;
+                if (!p)
+                        return r;
+                r = p;
+                haystack = p + 1;
+        }
 }
 
 #ifdef __DO_STRRSTR_TEST
-/* Test */
 int main(int argc, char **argv)
 {
-        int ret = 0;
-        int n;
-        char *tmp;
-
-        ret |= !(n = ((tmp = strrstr("baaabaaab", "aaa")) != NULL && strcmp(tmp, "aaab") == 0));
-        printf("'baaabaaab'  vs. 'aaa'       : %s\n", n ? "PASSED" : "FAILED");
-
-        ret |= !(n = ((tmp = strrstr("baaabaaaab", "aaa")) != NULL && strcmp(tmp, "aaab") == 0));
-        printf("'baaabaaaab' vs. 'aaa'       : %s\n", n ? "PASSED" : "FAILED");
-
-        ret |= !(n = ((tmp = strrstr("baaabaab", "aaa")) != NULL && strcmp(tmp, "aaabaab") == 0));
-        printf("'baaabaab'   vs. 'aaa'       : %s\n", n ? "PASSED" : "FAILED");
-
-        ret |= !(n = (strrstr("aaa", "aaa") != NULL));
-        printf("'aaa'        vs. 'aaa'       : %s\n", n ? "PASSED" : "FAILED");
-
-        ret |= !(n = (strrstr("aaa", "a") != NULL));
-        printf("'aaa'        vs. 'a'         : %s\n", n ? "PASSED" : "FAILED");
-
-        ret |= !(n = (strrstr("aaa", "bbb") == NULL));
-        printf("'aaa'        vs. 'bbb'       : %s\n", n ? "PASSED" : "FAILED");
-
-        ret |= !(n = (strrstr("a", "aaa") == NULL));
-        printf("'a'          vs. 'aaa'       : %s\n", n ? "PASSED" : "FAILED");
-
-        ret |= !(n = ((tmp = strrstr("aaa", "")) != NULL && strcmp(tmp, "aaa") == 0));
-        printf("'aaa'        vs. ''          : %s\n", n ? "FAILED" : "PASSED");
-
-        ret |= !(n = (strrstr("", "aaa") == NULL));
-        printf("''           vs. 'aaa'       : %s\n", n ? "PASSED" : "FAILED");
+        static const struct {
+                const char *h, *n;
+                int pos;
+        } test_array[] = {
+                /* 0123456789 */
+                { "baaabaaab",  "aaa", 5  },
+                { "baaabaaaab", "aaa", 6  },
+                { "baaabaab",   "aaa", 1  },
+                { "aaa",        "aaa", 0  },
+                { "aaa",        "a",   2  },
+                { "aaa",        "bbb", -1 },
+                { "a",          "aaa", -1 },
+                { "aaa",        "",    3  },
+                { "",           "aaa", -1 },
+                { "",           "",    0  },
+        };
 
-        ret |= !(n = ((tmp = strrstr("", "")) != NULL && strcmp(tmp, "") == 0));
-        printf("''           vs. ''          : %s\n", n ? "PASSED" : "FAILED");
+        int i;
 
-        /*ret |= !(n = (strrstr(NULL, NULL) == NULL));
-        printf("'NULL'       vs. 'NULL'      : %s\n", n ? "PASSED" : "FAILED");
-        ret |= !(n = (strrstr("", NULL) == NULL));
-        printf("''           vs. 'NULL'      : %s\n", n ? "PASSED" : "FAILED");
-        ret |= !(n = (strrstr(NULL, "") == NULL));
-        printf("'NULL'       vs. ''          : %s\n", n ? "PASSED" : "FAILED");
-        ret |= !(n = (strrstr("aaa", NULL) == NULL));
-        printf("'aaa'        vs. 'NULL'      : %s\n", n ? "PASSED" : "FAILED");
-        ret |= !(n = (strrstr(NULL, "aaa") == NULL));
-        printf("'NULL'       vs. 'aaa'       : %s\n", n ? "PASSED" : "FAILED");*/
+        i = 0;
+        while (i < sizeof(test_array) / sizeof(test_array[0])) {
+                const char *r = strrstr(test_array[i].h, test_array[i].n);
+                printf("'%s' vs. '%s': '%s' - ", test_array[i].h, test_array[i].n, r);
+                if (r == NULL)
+                        r = test_array[i].h - 1;
+                printf("%s\n", r == test_array[i].h + test_array[i].pos ? "PASSED" : "FAILED");
+                i++;
+        }
 
-        return ret;
+        return 0;
 }
 #endif