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#include "cache.h"
#include "tree-walk.h"
static const char merge_tree_usage[] = "git-merge-tree <base-tree> <branch1> <branch2>";
static int resolve_directories = 1;
static void merge_trees(struct tree_desc t[3], const char *base);
/* An empty entry never compares same, not even to another empty entry */
static int same_entry(struct name_entry *a, struct name_entry *b)
{
return a->sha1 &&
b->sha1 &&
!memcmp(a->sha1, b->sha1, 20) &&
a->mode == b->mode;
}
static const char *sha1_to_hex_zero(const unsigned char *sha1)
{
if (sha1)
return sha1_to_hex(sha1);
return "0000000000000000000000000000000000000000";
}
static void resolve(const char *base, struct name_entry *branch1, struct name_entry *result)
{
char branch1_sha1[50];
/* If it's already branch1, don't bother showing it */
if (!branch1)
return;
memcpy(branch1_sha1, sha1_to_hex_zero(branch1->sha1), 41);
printf("0 %06o->%06o %s->%s %s%s\n",
branch1->mode, result->mode,
branch1_sha1, sha1_to_hex_zero(result->sha1),
base, result->path);
}
static int unresolved_directory(const char *base, struct name_entry n[3])
{
int baselen;
char *newbase;
struct name_entry *p;
struct tree_desc t[3];
void *buf0, *buf1, *buf2;
if (!resolve_directories)
return 0;
p = n;
if (!p->mode) {
p++;
if (!p->mode)
p++;
}
if (!S_ISDIR(p->mode))
return 0;
baselen = strlen(base);
newbase = xmalloc(baselen + p->pathlen + 2);
memcpy(newbase, base, baselen);
memcpy(newbase + baselen, p->path, p->pathlen);
memcpy(newbase + baselen + p->pathlen, "/", 2);
buf0 = fill_tree_descriptor(t+0, n[0].sha1);
buf1 = fill_tree_descriptor(t+1, n[1].sha1);
buf2 = fill_tree_descriptor(t+2, n[2].sha1);
merge_trees(t, newbase);
free(buf0);
free(buf1);
free(buf2);
free(newbase);
return 1;
}
static void unresolved(const char *base, struct name_entry n[3])
{
if (unresolved_directory(base, n))
return;
if (n[0].sha1)
printf("1 %06o %s %s%s\n", n[0].mode, sha1_to_hex(n[0].sha1), base, n[0].path);
if (n[1].sha1)
printf("2 %06o %s %s%s\n", n[1].mode, sha1_to_hex(n[1].sha1), base, n[1].path);
if (n[2].sha1)
printf("3 %06o %s %s%s\n", n[2].mode, sha1_to_hex(n[2].sha1), base, n[2].path);
}
/*
* Merge two trees together (t[1] and t[2]), using a common base (t[0])
* as the origin.
*
* This walks the (sorted) trees in lock-step, checking every possible
* name. Note that directories automatically sort differently from other
* files (see "base_name_compare"), so you'll never see file/directory
* conflicts, because they won't ever compare the same.
*
* IOW, if a directory changes to a filename, it will automatically be
* seen as the directory going away, and the filename being created.
*
* Think of this as a three-way diff.
*
* The output will be either:
* - successful merge
* "0 mode sha1 filename"
* NOTE NOTE NOTE! FIXME! We really really need to walk the index
* in parallel with this too!
*
* - conflict:
* "1 mode sha1 filename"
* "2 mode sha1 filename"
* "3 mode sha1 filename"
* where not all of the 1/2/3 lines may exist, of course.
*
* The successful merge rules are the same as for the three-way merge
* in git-read-tree.
*/
static void threeway_callback(int n, unsigned long mask, struct name_entry *entry, const char *base)
{
/* Same in both? */
if (same_entry(entry+1, entry+2)) {
if (entry[0].sha1) {
resolve(base, NULL, entry+1);
return;
}
}
if (same_entry(entry+0, entry+1)) {
if (entry[2].sha1 && !S_ISDIR(entry[2].mode)) {
resolve(base, entry+1, entry+2);
return;
}
}
if (same_entry(entry+0, entry+2)) {
if (entry[1].sha1 && !S_ISDIR(entry[1].mode)) {
resolve(base, NULL, entry+1);
return;
}
}
unresolved(base, entry);
}
static void merge_trees(struct tree_desc t[3], const char *base)
{
traverse_trees(3, t, base, threeway_callback);
}
static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
{
unsigned char sha1[20];
void *buf;
if (get_sha1(rev, sha1) < 0)
die("unknown rev %s", rev);
buf = fill_tree_descriptor(desc, sha1);
if (!buf)
die("%s is not a tree", rev);
return buf;
}
int main(int argc, char **argv)
{
struct tree_desc t[3];
void *buf1, *buf2, *buf3;
if (argc < 4)
usage(merge_tree_usage);
buf1 = get_tree_descriptor(t+0, argv[1]);
buf2 = get_tree_descriptor(t+1, argv[2]);
buf3 = get_tree_descriptor(t+2, argv[3]);
merge_trees(t, "");
free(buf1);
free(buf2);
free(buf3);
return 0;
}
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