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![Daniel Barkalow](/assets/img/avatar_default.png)
The old implementation was a nice algorithm, but, unfortunately, it could be confused in some cases and would not necessarily do the obvious thing if one argument was decended from the other. This version fixes that by changing the criterion to the most recent common ancestor. Signed-Off-By: Daniel Barkalow <barkalow@iabervon.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
89 lines
2 KiB
C
89 lines
2 KiB
C
#include <stdlib.h>
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#include "cache.h"
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#include "commit.h"
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static struct commit *process_list(struct commit_list **list_p, int this_mark,
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int other_mark)
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{
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struct commit *item = (*list_p)->item;
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if (item->object.flags & this_mark) {
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/*
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printf("%d already seen %s %x\n",
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this_mark
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sha1_to_hex(posn->parent->sha1),
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posn->parent->flags);
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*/
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/* do nothing; this indicates that this side
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* split and reformed, and we only need to
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* mark it once.
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*/
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*list_p = (*list_p)->next;
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} else if (item->object.flags & other_mark) {
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return item;
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} else {
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/*
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printf("%d based on %s\n",
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this_mark,
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sha1_to_hex(posn->parent->sha1));
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*/
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pop_most_recent_commit(list_p);
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item->object.flags |= this_mark;
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}
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return NULL;
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}
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struct commit *common_ancestor(struct commit *rev1, struct commit *rev2)
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{
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struct commit_list *rev1list = NULL;
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struct commit_list *rev2list = NULL;
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commit_list_insert(rev1, &rev1list);
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commit_list_insert(rev2, &rev2list);
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parse_commit(rev1);
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parse_commit(rev2);
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while (rev1list || rev2list) {
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struct commit *ret;
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if (!rev1list) {
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// process 2
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ret = process_list(&rev2list, 0x2, 0x1);
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} else if (!rev2list) {
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// process 1
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ret = process_list(&rev1list, 0x1, 0x2);
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} else if (rev1list->item->date < rev2list->item->date) {
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// process 2
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ret = process_list(&rev2list, 0x2, 0x1);
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} else {
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// process 1
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ret = process_list(&rev1list, 0x1, 0x2);
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}
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if (ret) {
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free_commit_list(rev1list);
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free_commit_list(rev2list);
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return ret;
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}
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}
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return NULL;
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}
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int main(int argc, char **argv)
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{
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struct commit *rev1, *rev2, *ret;
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unsigned char rev1key[20], rev2key[20];
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if (argc != 3 ||
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get_sha1_hex(argv[1], rev1key) ||
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get_sha1_hex(argv[2], rev2key)) {
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usage("merge-base <commit-id> <commit-id>");
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}
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rev1 = lookup_commit(rev1key);
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rev2 = lookup_commit(rev2key);
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ret = common_ancestor(rev1, rev2);
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if (!ret)
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return 1;
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printf("%s\n", sha1_to_hex(ret->object.sha1));
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return 0;
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}
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