merge-tree.c

   1 #include "cache.h"
   2
   3 static int line_termination = '\n';
   4
   5 struct tree_entry {
   6         unsigned mode;
   7         unsigned char *sha1;
   8         char *path;
   9         struct tree_entry *next;
  10 };
  11
  12 static struct tree_entry *read_tree(unsigned char *sha1)
  13 {
  14         char type[20];
  15         unsigned long size;
  16         void *buf = read_sha1_file(sha1, type, &size);
  17         struct tree_entry *ret = NULL, **tp = &ret;
  18
  19         if (!buf || strcmp(type, "tree"))
  20                 die("unable to read 'tree' object %s", sha1_to_hex(sha1));
  21         while (size) {
  22                 int len = strlen(buf)+1;
  23                 struct tree_entry * entry = malloc(sizeof(struct tree_entry));
  24                 if (size < len + 20 || sscanf(buf, "%o", &entry->mode) != 1)
  25                         die("corrupt 'tree' object %s", sha1_to_hex(sha1));
  26                 entry->path = strchr(buf, ' ')+1;
  27                 entry->sha1 = buf + len;
  28                 entry->next = NULL;
  29                 *tp = entry;
  30                 tp = &entry->next;
  31                 len += 20;
  32                 buf += len;
  33                 size -= len;
  34         }
  35         return ret;
  36 }
  37
  38 static void show(const struct tree_entry *a, const char *path)
  39 {
  40         printf("select %o %s %s%c", a->mode, sha1_to_hex(a->sha1), path,
  41                line_termination);
  42 }
  43
  44 static void merge(const struct tree_entry *a, const struct tree_entry *b, const struct tree_entry *c, const char *path)
  45 {
  46         char hex_a[60], hex_b[60], hex_c[60];
  47         strcpy(hex_a, sha1_to_hex(a->sha1));
  48         strcpy(hex_b, sha1_to_hex(b->sha1));
  49         strcpy(hex_c, sha1_to_hex(c->sha1));
  50         printf("merge %o->%o,%o %s->%s,%s %s%c",
  51                 a->mode, b->mode, c->mode,
  52                 hex_a, hex_b, hex_c, path, line_termination);
  53 }
  54
  55 static int same(const struct tree_entry *a, const struct tree_entry *b)
  56 {
  57         return a->mode == b->mode && !memcmp(a->sha1, b->sha1, 20);
  58 }
  59
  60 static void merge_entry(const struct tree_entry *src, const struct tree_entry *dst1, const struct tree_entry *dst2)
  61 {
  62         static unsigned char nullsha1[20];
  63         static const struct tree_entry none = { 0, nullsha1, "", NULL };
  64         const char *path = NULL;
  65         const struct tree_entry *a, *b, *c;
  66
  67         a = &none;
  68         b = &none;
  69         c = &none;
  70         if (src) { a = src; path = src->path; }
  71         if (dst1) { b = dst1; path = dst1->path; }
  72         if (dst2) { c = dst2; path = dst2->path; }
  73         if (same(b, c)) {
  74                 show(b, path);
  75                 return;
  76         }
  77         if (same(a, b)) {
  78                 show(c, path);
  79                 return;
  80         }
  81         if (same(a, c)) {
  82                 show(b, path);
  83                 return;
  84         }
  85         merge(a, b, c, path);
  86 }
  87
  88 /* For two entries, select the smaller one, clear the bigger one */
  89 static void smaller(struct tree_entry **ap, struct tree_entry **bp)
  90 {
  91         struct tree_entry *a = *ap, *b = *bp;
  92         if (a && b) {
  93                 int cmp = cache_name_compare(a->path, strlen(a->path), b->path, strlen(b->path));
  94                 if (cmp) {
  95                         if (cmp < 0)
  96                                 *bp = NULL;
  97                         else
  98                                 *ap = NULL;
  99                 }
 100         }
 101 }
 102
 103 static void merge_tree(struct tree_entry *src, struct tree_entry *dst1, struct tree_entry *dst2)
 104 {
 105         while (src || dst1 || dst2) {
 106                 struct tree_entry *a, *b, *c;
 107                 a = src;
 108                 b = dst1;
 109                 c = dst2;
 110                 smaller(&a,&b);
 111                 smaller(&a,&c);
 112                 smaller(&b,&c);
 113                 if (a) src = a->next;
 114                 if (b) dst1 = b->next;
 115                 if (c) dst2 = c->next;
 116                 merge_entry(a,b,c);
 117         }
 118 }
 119
 120 static const char *merge_tree_usage =
 121     "merge-tree [-z] <src> <dst1> <dst2>";
 122
 123 int main(int argc, char **argv)
 124 {
 125         unsigned char src[20], dst1[20], dst2[20];
 126
 127         while ((1 < argc) && argv[1][0] == '-') {
 128                 switch (argv[1][1]) {
 129                 case 'z':
 130                         line_termination = 0;
 131                         break;
 132                 default:
 133                         usage(merge_tree_usage);
 134                 }
 135                 argc--; argv++;
 136         }
 137
 138         if (argc != 4 ||
 139             get_sha1_hex(argv[1], src) ||
 140             get_sha1_hex(argv[2], dst1) ||
 141             get_sha1_hex(argv[3], dst2))
 142                 usage(merge_tree_usage);
 143         merge_tree(read_tree(src), read_tree(dst1), read_tree(dst2));
 144         return 0;
 145 }