versioncmp.con commit Merge branch 'jk/describe-omit-some-refs' (1b32498)
   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
  24static const struct string_list *prereleases;
  25static int initialized;
  26
  27struct suffix_match {
  28        int conf_pos;
  29        int start;
  30        int len;
  31};
  32
  33static 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 */
  70static 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
 115int 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}