versioncmp.c

   1 #include "cache.h"
   2 #include "string-list.h"
   3
   4 /*
   5  * versioncmp(): copied from string/strverscmp.c in glibc commit
   6  * ee9247c38a8def24a59eb5cfb7196a98bef8cfdc, reformatted to Git coding
   7  * style. The implementation is under LGPL-2.1 and Git relicenses it
   8  * to GPLv2.
   9  */
  10
  11 /*
  12  * states: S_N: normal, S_I: comparing integral part, S_F: comparing
  13  * fractionnal parts, S_Z: idem but with leading Zeroes only
  14  */
  15 #define  S_N    0x0
  16 #define  S_I    0x3
  17 #define  S_F    0x6
  18 #define  S_Z    0x9
  19
  20 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */
  21 #define  CMP    2
  22 #define  LEN    3
  23
  24 static const struct string_list *prereleases;
  25 static int initialized;
  26
  27 /*
  28  * off is the offset of the first different character in the two strings
  29  * s1 and s2. If either s1 or s2 contains a prerelease suffix containing
  30  * that offset or a suffix ends right before that offset, then that
  31  * string will be forced to be on top.
  32  *
  33  * If both s1 and s2 contain a (different) suffix around that position,
  34  * their order is determined by the order of those two suffixes in the
  35  * configuration.
  36  * If any of the strings contains more than one different suffixes around
  37  * that position, then that string is sorted according to the contained
  38  * suffix which starts at the earliest offset in that string.
  39  * If more than one different contained suffixes start at that earliest
  40  * offset, then that string is sorted according to the longest of those
  41  * suffixes.
  42  *
  43  * Return non-zero if *diff contains the return value for versioncmp()
  44  */
  45 static int swap_prereleases(const char *s1,
  46                             const char *s2,
  47                             int off,
  48                             int *diff)
  49 {
  50         int i, i1 = -1, i2 = -1;
  51         int start_at1 = off, start_at2 = off, match_len1 = -1, match_len2 = -1;
  52
  53         for (i = 0; i < prereleases->nr; i++) {
  54                 const char *suffix = prereleases->items[i].string;
  55                 int j, start, end, suffix_len = strlen(suffix);
  56                 if (suffix_len < off)
  57                         start = off - suffix_len;
  58                 else
  59                         start = 0;
  60                 end = match_len1 < suffix_len ? start_at1 : start_at1-1;
  61                 for (j = start; j <= end; j++)
  62                         if (starts_with(s1 + j, suffix)) {
  63                                 i1 = i;
  64                                 start_at1 = j;
  65                                 match_len1 = suffix_len;
  66                                 break;
  67                         }
  68                 end = match_len2 < suffix_len ? start_at2 : start_at2-1;
  69                 for (j = start; j <= end; j++)
  70                         if (starts_with(s2 + j, suffix)) {
  71                                 i2 = i;
  72                                 start_at2 = j;
  73                                 match_len2 = suffix_len;
  74                                 break;
  75                         }
  76         }
  77         if (i1 == -1 && i2 == -1)
  78                 return 0;
  79         if (i1 == i2)
  80                 /* Found the same suffix in both, e.g. "-rc" in "v1.0-rcX"
  81                  * and "v1.0-rcY": the caller should decide based on "X"
  82                  * and "Y". */
  83                 return 0;
  84
  85         if (i1 >= 0 && i2 >= 0)
  86                 *diff = i1 - i2;
  87         else if (i1 >= 0)
  88                 *diff = -1;
  89         else /* if (i2 >= 0) */
  90                 *diff = 1;
  91         return 1;
  92 }
  93
  94 /*
  95  * Compare S1 and S2 as strings holding indices/version numbers,
  96  * returning less than, equal to or greater than zero if S1 is less
  97  * than, equal to or greater than S2 (for more info, see the texinfo
  98  * doc).
  99  */
 100
 101 int versioncmp(const char *s1, const char *s2)
 102 {
 103         const unsigned char *p1 = (const unsigned char *) s1;
 104         const unsigned char *p2 = (const unsigned char *) s2;
 105         unsigned char c1, c2;
 106         int state, diff;
 107
 108         /*
 109          * Symbol(s)    0       [1-9]   others
 110          * Transition   (10) 0  (01) d  (00) x
 111          */
 112         static const uint8_t next_state[] = {
 113                 /* state    x    d    0  */
 114                 /* S_N */  S_N, S_I, S_Z,
 115                 /* S_I */  S_N, S_I, S_I,
 116                 /* S_F */  S_N, S_F, S_F,
 117                 /* S_Z */  S_N, S_F, S_Z
 118         };
 119
 120         static const int8_t result_type[] = {
 121                 /* state   x/x  x/d  x/0  d/x  d/d  d/0  0/x  0/d  0/0  */
 122
 123                 /* S_N */  CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
 124                 /* S_I */  CMP, -1,  -1,  +1,  LEN, LEN, +1,  LEN, LEN,
 125                 /* S_F */  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
 126                 /* S_Z */  CMP, +1,  +1,  -1,  CMP, CMP, -1,  CMP, CMP
 127         };
 128
 129         if (p1 == p2)
 130                 return 0;
 131
 132         c1 = *p1++;
 133         c2 = *p2++;
 134         /* Hint: '0' is a digit too.  */
 135         state = S_N + ((c1 == '0') + (isdigit (c1) != 0));
 136
 137         while ((diff = c1 - c2) == 0) {
 138                 if (c1 == '\0')
 139                         return diff;
 140
 141                 state = next_state[state];
 142                 c1 = *p1++;
 143                 c2 = *p2++;
 144                 state += (c1 == '0') + (isdigit (c1) != 0);
 145         }
 146
 147         if (!initialized) {
 148                 initialized = 1;
 149                 prereleases = git_config_get_value_multi("versionsort.prereleasesuffix");
 150         }
 151         if (prereleases && swap_prereleases(s1, s2, (const char *) p1 - s1 - 1,
 152                                             &diff))
 153                 return diff;
 154
 155         state = result_type[state * 3 + (((c2 == '0') + (isdigit (c2) != 0)))];
 156
 157         switch (state) {
 158         case CMP:
 159                 return diff;
 160
 161         case LEN:
 162                 while (isdigit (*p1++))
 163                         if (!isdigit (*p2++))
 164                                 return 1;
 165
 166                 return isdigit (*p2) ? -1 : diff;
 167
 168         default:
 169                 return state;
 170         }
 171 }