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         char tag[1];
  29 };
  30
  31 static struct revision **revs;
  32 static int nr_revs, rev_allocs;
  33
  34 static int find_rev(unsigned char *sha1)
  35 {
  36         int first = 0, last = nr_revs;
  37
  38         while (first < last) {
  39                 int next = (first + last) / 2;
  40                 struct revision *rev = revs[next];
  41                 int cmp;
  42
  43                 cmp = memcmp(sha1, rev->sha1, 20);
  44                 if (!cmp)
  45                         return next;
  46                 if (cmp < 0) {
  47                         last = next;
  48                         continue;
  49                 }
  50                 first = next+1;
  51         }
  52         return -first-1;
  53 }
  54
  55 static struct revision *lookup_rev(unsigned char *sha1, const char *tag)
  56 {
  57         int pos = find_rev(sha1);
  58         struct revision *n;
  59
  60         if (pos >= 0) {
  61                 n = revs[pos];
  62                 if (strcmp(n->tag, tag))
  63                         error("expected tag %s on object %s: got %s", tag, sha1_to_hex(sha1), n->tag);
  64                 return n;
  65         }
  66
  67         pos = -pos-1;
  68
  69         if (rev_allocs == nr_revs) {
  70                 rev_allocs = alloc_nr(rev_allocs);
  71                 revs = realloc(revs, rev_allocs * sizeof(struct revision *));
  72         }
  73         n = malloc(sizeof(struct revision) + strlen(tag));
  74
  75         n->flags = 0;
  76         memcpy(n->sha1, sha1, 20);
  77         n->parent = NULL;
  78         strcpy(n->tag, tag);
  79
  80         /* Insert it into the right place */
  81         memmove(revs + pos + 1, revs + pos, (nr_revs - pos) * sizeof(struct revision *));
  82         revs[pos] = n;
  83         nr_revs++;
  84
  85         return n;
  86 }
  87
  88 static struct revision *add_relationship(struct revision *rev, unsigned char *needs, const char *tag)
  89 {
  90         struct revision *parent_rev = lookup_rev(needs, tag);
  91         struct parent **pp = &rev->parent, *p;
  92
  93         while ((p = *pp) != NULL) {
  94                 if (p->parent == parent_rev)
  95                         return parent_rev;
  96                 pp = &p->next;
  97         }
  98
  99         p = malloc(sizeof(*p));
 100         p->parent = parent_rev;
 101         p->next = NULL;
 102         *pp = p;
 103         return parent_rev;
 104 }
 105
 106 static void mark_reachable(struct revision *rev, unsigned int mask)
 107 {
 108         struct parent *p = rev->parent;
 109
 110         /* If we've been here already, don't bother */
 111         if (rev->flags & mask)
 112                 return;
 113         rev->flags |= mask | USED;
 114         while (p) {
 115                 mark_reachable(p->parent, mask);
 116                 p = p->next;
 117         }
 118 }
 119
 120 static unsigned long parse_commit_date(const char *buf)
 121 {
 122         unsigned long date;
 123
 124         if (memcmp(buf, "author", 6))
 125                 return 0;
 126         while (*buf++ != '\n')
 127                 /* nada */;
 128         if (memcmp(buf, "committer", 9))
 129                 return 0;
 130         while (*buf++ != '>')
 131                 /* nada */;
 132         date = strtoul(buf, NULL, 10);
 133         if (date == ULONG_MAX)
 134                 date = 0;
 135         return date;
 136 }
 137
 138 static struct revision * parse_commit(unsigned char *sha1)
 139 {
 140         struct revision *rev = lookup_rev(sha1, "commit");
 141
 142         if (!(rev->flags & SEEN)) {
 143                 void *buffer, *bufptr;
 144                 unsigned long size;
 145                 char type[20];
 146                 unsigned char parent[20];
 147
 148                 rev->flags |= SEEN;
 149                 buffer = bufptr = read_sha1_file(sha1, type, &size);
 150                 if (!buffer || strcmp(type, "commit"))
 151                         die("%s is not a commit object", sha1_to_hex(sha1));
 152                 bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 153                 while (!memcmp(bufptr, "parent ", 7) && !get_sha1_hex(bufptr+7, parent)) {
 154                         add_relationship(rev, parent, "commit");
 155                         parse_commit(parent);
 156                         bufptr += 48;   /* "parent " + "hex sha1" + "\n" */
 157                 }
 158                 rev->date = parse_commit_date(bufptr);
 159                 free(buffer);
 160         }
 161         return rev;
 162 }
 163
 164 #endif /* REVISION_H */