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 struct suffix_match {
  28         int conf_pos;
  29         int start;
  30         int len;
  31 };
  32
  33 static void find_better_matching_suffix(const char *tagname, const char *suffix,
  34                                         int suffix_len, int start, int conf_pos,
  35                                         struct suffix_match *match)
  36 {
  37         /*
  38          * A better match either starts earlier or starts at the same offset
  39          * but is longer.
  40          */
  41         int end = match->len < suffix_len ? match->start : match->start-1;
  42         int i;
  43         for (i = start; i <= end; i++)
  44                 if (starts_with(tagname + i, suffix)) {
  45                         match->conf_pos = conf_pos;
  46                         match->start = i;
  47                         match->len = suffix_len;
  48                         break;
  49                 }
  50 }
  51
  52 /*
  53  * off is the offset of the first different character in the two strings
  54  * s1 and s2. If either s1 or s2 contains a prerelease suffix containing
  55  * that offset or a suffix ends right before that offset, then that
  56  * string will be forced to be on top.
  57  *
  58  * If both s1 and s2 contain a (different) suffix around that position,
  59  * their order is determined by the order of those two suffixes in the
  60  * configuration.
  61  * If any of the strings contains more than one different suffixes around
  62  * that position, then that string is sorted according to the contained
  63  * suffix which starts at the earliest offset in that string.
  64  * If more than one different contained suffixes start at that earliest
  65  * offset, then that string is sorted according to the longest of those
  66  * suffixes.
  67  *
  68  * Return non-zero if *diff contains the return value for versioncmp()
  69  */
  70 static int swap_prereleases(const char *s1,
  71                             const char *s2,
  72                             int off,
  73                             int *diff)
  74 {
  75         int i;
  76         struct suffix_match match1 = { -1, off, -1 };
  77         struct suffix_match match2 = { -1, off, -1 };
  78
  79         for (i = 0; i < prereleases->nr; i++) {
  80                 const char *suffix = prereleases->items[i].string;
  81                 int start, suffix_len = strlen(suffix);
  82                 if (suffix_len < off)
  83                         start = off - suffix_len;
  84                 else
  85                         start = 0;
  86                 find_better_matching_suffix(s1, suffix, suffix_len, start,
  87                                             i, &match1);
  88                 find_better_matching_suffix(s2, suffix, suffix_len, start,
  89                                             i, &match2);
  90         }
  91         if (match1.conf_pos == -1 && match2.conf_pos == -1)
  92                 return 0;
  93         if (match1.conf_pos == match2.conf_pos)
  94                 /* Found the same suffix in both, e.g. "-rc" in "v1.0-rcX"
  95                  * and "v1.0-rcY": the caller should decide based on "X"
  96                  * and "Y". */
  97                 return 0;
  98
  99         if (match1.conf_pos >= 0 && match2.conf_pos >= 0)
 100                 *diff = match1.conf_pos - match2.conf_pos;
 101         else if (match1.conf_pos >= 0)
 102                 *diff = -1;
 103         else /* if (match2.conf_pos >= 0) */
 104                 *diff = 1;
 105         return 1;
 106 }
 107
 108 /*
 109  * Compare S1 and S2 as strings holding indices/version numbers,
 110  * returning less than, equal to or greater than zero if S1 is less
 111  * than, equal to or greater than S2 (for more info, see the texinfo
 112  * doc).
 113  */
 114
 115 int versioncmp(const char *s1, const char *s2)
 116 {
 117         const unsigned char *p1 = (const unsigned char *) s1;
 118         const unsigned char *p2 = (const unsigned char *) s2;
 119         unsigned char c1, c2;
 120         int state, diff;
 121
 122         /*
 123          * Symbol(s)    0       [1-9]   others
 124          * Transition   (10) 0  (01) d  (00) x
 125          */
 126         static const uint8_t next_state[] = {
 127                 /* state    x    d    0  */
 128                 /* S_N */  S_N, S_I, S_Z,
 129                 /* S_I */  S_N, S_I, S_I,
 130                 /* S_F */  S_N, S_F, S_F,
 131                 /* S_Z */  S_N, S_F, S_Z
 132         };
 133
 134         static const int8_t result_type[] = {
 135                 /* state   x/x  x/d  x/0  d/x  d/d  d/0  0/x  0/d  0/0  */
 136
 137                 /* S_N */  CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
 138                 /* S_I */  CMP, -1,  -1,  +1,  LEN, LEN, +1,  LEN, LEN,
 139                 /* S_F */  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
 140                 /* S_Z */  CMP, +1,  +1,  -1,  CMP, CMP, -1,  CMP, CMP
 141         };
 142
 143         if (p1 == p2)
 144                 return 0;
 145
 146         c1 = *p1++;
 147         c2 = *p2++;
 148         /* Hint: '0' is a digit too.  */
 149         state = S_N + ((c1 == '0') + (isdigit (c1) != 0));
 150
 151         while ((diff = c1 - c2) == 0) {
 152                 if (c1 == '\0')
 153                         return diff;
 154
 155                 state = next_state[state];
 156                 c1 = *p1++;
 157                 c2 = *p2++;
 158                 state += (c1 == '0') + (isdigit (c1) != 0);
 159         }
 160
 161         if (!initialized) {
 162                 const struct string_list *deprecated_prereleases;
 163                 initialized = 1;
 164                 prereleases = git_config_get_value_multi("versionsort.suffix");
 165                 deprecated_prereleases = git_config_get_value_multi("versionsort.prereleasesuffix");
 166                 if (prereleases) {
 167                         if (deprecated_prereleases)
 168                                 warning("ignoring versionsort.prereleasesuffix because versionsort.suffix is set");
 169                 } else
 170                         prereleases = deprecated_prereleases;
 171         }
 172         if (prereleases && swap_prereleases(s1, s2, (const char *) p1 - s1 - 1,
 173                                             &diff))
 174                 return diff;
 175
 176         state = result_type[state * 3 + (((c2 == '0') + (isdigit (c2) != 0)))];
 177
 178         switch (state) {
 179         case CMP:
 180                 return diff;
 181
 182         case LEN:
 183                 while (isdigit (*p1++))
 184                         if (!isdigit (*p2++))
 185                                 return 1;
 186
 187                 return isdigit (*p2) ? -1 : diff;
 188
 189         default:
 190                 return state;
 191         }
 192 }