merge-tree.c

   1 #include "cache.h"
   2
   3 struct tree_entry {
   4         unsigned mode;
   5         unsigned char *sha1;
   6         char *path;
   7         struct tree_entry *next;
   8 };
   9
  10 static struct tree_entry *read_tree(unsigned char *sha1)
  11 {
  12         char type[20];
  13         unsigned long size;
  14         void *buf = read_sha1_file(sha1, type, &size);
  15         struct tree_entry *ret = NULL, **tp = &ret;
  16
  17         if (!buf || strcmp(type, "tree"))
  18                 die("unable to read 'tree' object %s", sha1_to_hex(sha1));
  19         while (size) {
  20                 int len = strlen(buf)+1;
  21                 struct tree_entry * entry = malloc(sizeof(struct tree_entry));
  22                 if (size < len + 20 || sscanf(buf, "%o", &entry->mode) != 1)
  23                         die("corrupt 'tree' object %s", sha1_to_hex(sha1));
  24                 entry->path = strchr(buf, ' ')+1;
  25                 entry->sha1 = buf + len;
  26                 entry->next = NULL;
  27                 *tp = entry;
  28                 tp = &entry->next;
  29                 len += 20;
  30                 buf += len;
  31                 size -= len;
  32         }
  33         return ret;
  34 }
  35
  36 static void show(const struct tree_entry *a, const char *path)
  37 {
  38         printf("select %o %s %s%c", a->mode, sha1_to_hex(a->sha1), path, 0);
  39 }
  40
  41 static void merge(const struct tree_entry *a, const struct tree_entry *b, const struct tree_entry *c, const char *path)
  42 {
  43         char hex_a[60], hex_b[60], hex_c[60];
  44         strcpy(hex_a, sha1_to_hex(a->sha1));
  45         strcpy(hex_b, sha1_to_hex(b->sha1));
  46         strcpy(hex_c, sha1_to_hex(c->sha1));
  47         printf("merge %o->%o,%o %s->%s,%s %s%c",
  48                 a->mode, b->mode, c->mode,
  49                 hex_a, hex_b, hex_c, path, 0);
  50 }
  51
  52 static int same(const struct tree_entry *a, const struct tree_entry *b)
  53 {
  54         return a->mode == b->mode && !memcmp(a->sha1, b->sha1, 20);
  55 }
  56
  57 static void merge_entry(const struct tree_entry *src, const struct tree_entry *dst1, const struct tree_entry *dst2)
  58 {
  59         static unsigned char nullsha1[20];
  60         static const struct tree_entry none = { 0, nullsha1, "", NULL };
  61         const char *path = NULL;
  62         const struct tree_entry *a, *b, *c;
  63
  64         a = &none;
  65         b = &none;
  66         c = &none;
  67         if (src) { a = src; path = src->path; }
  68         if (dst1) { b = dst1; path = dst1->path; }
  69         if (dst2) { c = dst2; path = dst2->path; }
  70         if (same(b, c)) {
  71                 show(b, path);
  72                 return;
  73         }
  74         if (same(a, b)) {
  75                 show(c, path);
  76                 return;
  77         }
  78         if (same(a, c)) {
  79                 show(b, path);
  80                 return;
  81         }
  82         merge(a, b, c, path);
  83 }
  84
  85 /* For two entries, select the smaller one, clear the bigger one */
  86 static void smaller(struct tree_entry **ap, struct tree_entry **bp)
  87 {
  88         struct tree_entry *a = *ap, *b = *bp;
  89         if (a && b) {
  90                 int cmp = cache_name_compare(a->path, strlen(a->path), b->path, strlen(b->path));
  91                 if (cmp) {
  92                         if (cmp < 0)
  93                                 *bp = NULL;
  94                         else
  95                                 *ap = NULL;
  96                 }
  97         }
  98 }
  99
 100 static void merge_tree(struct tree_entry *src, struct tree_entry *dst1, struct tree_entry *dst2)
 101 {
 102         while (src || dst1 || dst2) {
 103                 struct tree_entry *a, *b, *c;
 104                 a = src;
 105                 b = dst1;
 106                 c = dst2;
 107                 smaller(&a,&b);
 108                 smaller(&a,&c);
 109                 smaller(&b,&c);
 110                 if (a) src = a->next;
 111                 if (b) dst1 = b->next;
 112                 if (c) dst2 = c->next;
 113                 merge_entry(a,b,c);
 114         }
 115 }
 116
 117 int main(int argc, char **argv)
 118 {
 119         unsigned char src[20], dst1[20], dst2[20];
 120
 121         if (argc != 4 ||
 122             get_sha1_hex(argv[1], src) ||
 123             get_sha1_hex(argv[2], dst1) ||
 124             get_sha1_hex(argv[3], dst2))
 125                 usage("merge-tree <src> <dst1> <dst2>");
 126         merge_tree(read_tree(src), read_tree(dst1), read_tree(dst2));
 127         return 0;
 128 }