revision.h

   1 #ifndef REVISION_H
   2 #define REVISION_H
   3
   4 /*
   5  * The low 16 bits of the "flags" field shows whether
   6  * a commit is part of the path to the root for that
   7  * parent.
   8  *
   9  * Bit 16 is an internal flag that we've seen the
  10  * definition for this rev, and not just seen it as
  11  * a parent target.
  12  */
  13 #define marked(rev)     ((rev)->flags & 0xffff)
  14 #define SEEN 0x10000
  15 #define USED 0x20000
  16 #define REACHABLE 0x40000
  17
  18 struct parent {
  19         struct revision *parent;
  20         struct parent *next;
  21 };
  22
  23 struct revision {
  24         unsigned int flags;
  25         unsigned char sha1[20];
  26         unsigned long date;
  27         struct parent *parent;
  28 };
  29
  30 static struct revision **revs;
  31 static int nr_revs, rev_allocs;
  32
  33 static int find_rev(unsigned char *sha1)
  34 {
  35         int first = 0, last = nr_revs;
  36
  37         while (first < last) {
  38                 int next = (first + last) / 2;
  39                 struct revision *rev = revs[next];
  40                 int cmp;
  41
  42                 cmp = memcmp(sha1, rev->sha1, 20);
  43                 if (!cmp)
  44                         return next;
  45                 if (cmp < 0) {
  46                         last = next;
  47                         continue;
  48                 }
  49                 first = next+1;
  50         }
  51         return -first-1;
  52 }
  53
  54 static struct revision *lookup_rev(unsigned char *sha1)
  55 {
  56         int pos = find_rev(sha1);
  57         struct revision *n;
  58
  59         if (pos >= 0)
  60                 return revs[pos];
  61
  62         pos = -pos-1;
  63
  64         if (rev_allocs == nr_revs) {
  65                 rev_allocs = alloc_nr(rev_allocs);
  66                 revs = realloc(revs, rev_allocs * sizeof(struct revision *));
  67         }
  68         n = malloc(sizeof(struct revision));
  69
  70         n->flags = 0;
  71         memcpy(n->sha1, sha1, 20);
  72         n->parent = NULL;
  73
  74         /* Insert it into the right place */
  75         memmove(revs + pos + 1, revs + pos, (nr_revs - pos) * sizeof(struct revision *));
  76         revs[pos] = n;
  77         nr_revs++;
  78
  79         return n;
  80 }
  81
  82 static struct revision *add_relationship(struct revision *rev, unsigned char *needs)
  83 {
  84         struct revision *parent_rev = lookup_rev(needs);
  85         struct parent **pp = &rev->parent, *p;
  86
  87         while ((p = *pp) != NULL) {
  88                 if (p->parent == parent_rev)
  89                         return parent_rev;
  90                 pp = &p->next;
  91         }
  92
  93         p = malloc(sizeof(*p));
  94         p->parent = parent_rev;
  95         p->next = NULL;
  96         *pp = p;
  97         return parent_rev;
  98 }
  99
 100 static void mark_reachable(struct revision *rev, unsigned int mask)
 101 {
 102         struct parent *p = rev->parent;
 103
 104         /* If we've been here already, don't bother */
 105         if (rev->flags & mask)
 106                 return;
 107         rev->flags |= mask | USED;
 108         while (p) {
 109                 mark_reachable(p->parent, mask);
 110                 p = p->next;
 111         }
 112 }
 113
 114 static unsigned long parse_commit_date(const char *buf)
 115 {
 116         unsigned long date;
 117
 118         if (memcmp(buf, "author", 6))
 119                 return 0;
 120         while (*buf++ != '\n')
 121                 /* nada */;
 122         if (memcmp(buf, "committer", 9))
 123                 return 0;
 124         while (*buf++ != '>')
 125                 /* nada */;
 126         date = strtoul(buf, NULL, 10);
 127         if (date == ULONG_MAX)
 128                 date = 0;
 129         return date;
 130 }
 131
 132 static int parse_commit(unsigned char *sha1)
 133 {
 134         struct revision *rev = lookup_rev(sha1);
 135
 136         if (!(rev->flags & SEEN)) {
 137                 void *buffer, *bufptr;
 138                 unsigned long size;
 139                 char type[20];
 140                 unsigned char parent[20];
 141
 142                 rev->flags |= SEEN;
 143                 buffer = bufptr = read_sha1_file(sha1, type, &size);
 144                 if (!buffer || strcmp(type, "commit"))
 145                         return -1;
 146                 bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 147                 while (!memcmp(bufptr, "parent ", 7) && !get_sha1_hex(bufptr+7, parent)) {
 148                         add_relationship(rev, parent);
 149                         parse_commit(parent);
 150                         bufptr += 48;   /* "parent " + "hex sha1" + "\n" */
 151                 }
 152                 rev->date = parse_commit_date(bufptr);
 153                 free(buffer);
 154         }
 155         return 0;
 156 }
 157
 158 #endif /* REVISION_H */