Add "merge-tree" helper program. Maybe it's retarded, maybe it's helpful.

It only works one directory level at a time, so lookout..

diff --git a/Makefile b/Makefile
index 92de1cb..b157273 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -14,7 +14,7 @@ CC=gcc
 
 PROG=   update-cache show-diff init-db write-tree read-tree commit-tree \
        cat-file fsck-cache checkout-cache diff-tree rev-tree show-files \
-       check-files ls-tree
+       check-files ls-tree merge-tree
 
 all: $(PROG)
 
@@ -64,6 +64,9 @@ check-files: check-files.o read-cache.o
 ls-tree: ls-tree.o read-cache.o
        $(CC) $(CFLAGS) -o ls-tree ls-tree.o read-cache.o $(LIBS)
 
+merge-tree: merge-tree.o read-cache.o
+       $(CC) $(CFLAGS) -o merge-tree merge-tree.o read-cache.o $(LIBS)
+
 read-cache.o: cache.h
 show-diff.o: cache.h
 

diff --git a/merge-tree.c b/merge-tree.c
new file mode 100644 (file)
index 0000000..00ae4e8
--- /dev/null
+++ b/merge-tree.c
@@ -0,0 +1,128 @@
+#include "cache.h"
+
+struct tree_entry {
+       unsigned mode;
+       unsigned char *sha1;
+       char *path;
+       struct tree_entry *next;
+};
+
+static struct tree_entry *read_tree(unsigned char *sha1)
+{
+       char type[20];
+       unsigned long size;
+       void *buf = read_sha1_file(sha1, type, &size);
+       struct tree_entry *ret = NULL, **tp = &ret;
+
+       if (!buf || strcmp(type, "tree"))
+               die("unable to read 'tree' object %s", sha1_to_hex(sha1));
+       while (size) {
+               int len = strlen(buf)+1;
+               struct tree_entry * entry = malloc(sizeof(struct tree_entry));
+               if (size < len + 20 || sscanf(buf, "%o", &entry->mode) != 1)
+                       die("corrupt 'tree' object %s", sha1_to_hex(sha1));
+               entry->path = strchr(buf, ' ')+1;
+               entry->sha1 = buf + len;
+               entry->next = NULL;
+               *tp = entry;
+               tp = &entry->next;
+               len += 20;
+               buf += len;
+               size -= len;
+       }
+       return ret;
+}
+
+static void show(const struct tree_entry *a, const char *path)
+{
+       printf("select %o %s %s%c", a->mode, sha1_to_hex(a->sha1), path, 0);
+}
+
+static void merge(const struct tree_entry *a, const struct tree_entry *b, const struct tree_entry *c, const char *path)
+{
+       char hex_a[60], hex_b[60], hex_c[60];
+       strcpy(hex_a, sha1_to_hex(a->sha1));
+       strcpy(hex_b, sha1_to_hex(b->sha1));
+       strcpy(hex_c, sha1_to_hex(c->sha1));
+       printf("merge %o->%o,%o %s->%s,%s %s%c",
+               a->mode, b->mode, c->mode,
+               hex_a, hex_b, hex_c, path, 0);
+}
+
+static int same(const struct tree_entry *a, const struct tree_entry *b)
+{
+       return a->mode == b->mode && !memcmp(a->sha1, b->sha1, 20);
+}
+
+static void merge_entry(const struct tree_entry *src, const struct tree_entry *dst1, const struct tree_entry *dst2)
+{
+       static unsigned char nullsha1[20];
+       static const struct tree_entry none = { 0, nullsha1, "", NULL };
+       const char *path = NULL;
+       const struct tree_entry *a, *b, *c;
+
+       a = &none;
+       b = &none;
+       c = &none;
+       if (src) { a = src; path = src->path; }
+       if (dst1) { b = dst1; path = dst1->path; }
+       if (dst2) { c = dst2; path = dst2->path; }
+       if (same(b, c)) {
+               show(b, path);
+               return;
+       }
+       if (same(a, b)) {
+               show(c, path);
+               return;
+       }
+       if (same(a, c)) {
+               show(b, path);
+               return;
+       }
+       merge(a, b, c, path);
+}
+
+/* For two entries, select the smaller one, clear the bigger one */
+static void smaller(struct tree_entry **ap, struct tree_entry **bp)
+{
+       struct tree_entry *a = *ap, *b = *bp;
+       if (a && b) {
+               int cmp = cache_name_compare(a->path, strlen(a->path), b->path, strlen(b->path));
+               if (cmp) {
+                       if (cmp < 0)
+                               *bp = NULL;
+                       else
+                               *ap = NULL;
+               }
+       }
+}
+
+static void merge_tree(struct tree_entry *src, struct tree_entry *dst1, struct tree_entry *dst2)
+{
+       while (src || dst1 || dst2) {
+               struct tree_entry *a, *b, *c;
+               a = src;
+               b = dst1;
+               c = dst2;
+               smaller(&a,&b);
+               smaller(&a,&c);
+               smaller(&b,&c);
+               if (a) src = a->next;
+               if (b) dst1 = b->next;
+               if (c) dst2 = c->next;
+               merge_entry(a,b,c);
+       }
+}
+
+int main(int argc, char **argv)
+{
+       unsigned char src[20], dst1[20], dst2[20];
+
+       if (argc != 4 ||
+           get_sha1_hex(argv[1], src) ||
+           get_sha1_hex(argv[2], dst1) ||
+           get_sha1_hex(argv[3], dst2))
+               usage("merge-tree <src> <dst1> <dst2>");
+       merge_tree(read_tree(src), read_tree(dst1), read_tree(dst2));
+       return 0;
+}