libbb/strrstr.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) 2008 Bernhard Reutner-Fischer
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9 #include "libbb.h"
  10
  11 /*
  12  * The strrstr() function finds the last occurrence of the substring needle
  13  * in the string haystack. The terminating nul characters are not compared.
  14  */
  15 char* FAST_FUNC strrstr(const char *haystack, const char *needle)
  16 {
  17         char *r = NULL;
  18
  19         if (!needle[0])
  20                 return (char*)haystack + strlen(haystack);
  21         while (1) {
  22                 char *p = strstr(haystack, needle);
  23                 if (!p)
  24                         return r;
  25                 r = p;
  26                 haystack = p + 1;
  27         }
  28 }
  29
  30 #if ENABLE_UNIT_TEST
  31
  32 BBUNIT_DEFINE_TEST(strrstr)
  33 {
  34         static const struct {
  35                 const char *h, *n;
  36                 int pos;
  37         } test_array[] = {
  38                 /* 0123456789 */
  39                 { "baaabaaab",  "aaa", 5  },
  40                 { "baaabaaaab", "aaa", 6  },
  41                 { "baaabaab",   "aaa", 1  },
  42                 { "aaa",        "aaa", 0  },
  43                 { "aaa",        "a",   2  },
  44                 { "aaa",        "bbb", -1 },
  45                 { "a",          "aaa", -1 },
  46                 { "aaa",        "",    3  },
  47                 { "",           "aaa", -1 },
  48                 { "",           "",    0  },
  49         };
  50
  51         int i;
  52
  53         i = 0;
  54         while (i < sizeof(test_array) / sizeof(test_array[0])) {
  55                 const char *r = strrstr(test_array[i].h, test_array[i].n);
  56                 if (r == NULL)
  57                         r = test_array[i].h - 1;
  58                 BBUNIT_ASSERT_EQ(r, test_array[i].h + test_array[i].pos);
  59                 i++;
  60         }
  61
  62         BBUNIT_ENDTEST;
  63 }
  64
  65 #endif /* ENABLE_UNIT_TEST */