diff options
Diffstat (limited to 'read-tree.c')
| -rw-r--r-- | read-tree.c | 81 |
1 files changed, 77 insertions, 4 deletions
diff --git a/read-tree.c b/read-tree.c index ee7a46c90..f2a8bb53a 100644 --- a/read-tree.c +++ b/read-tree.c @@ -210,6 +210,58 @@ static int twoway_merge(struct cache_entry **src, struct cache_entry **dst) } /* + * Two-way merge emulated with three-way merge. + * + * This treats "read-tree -m H M" by transforming it internally + * into "read-tree -m H I+H M", where I+H is a tree that would + * contain the contents of the current index file, overlayed on + * top of H. Unlike the traditional two-way merge, this leaves + * the stages in the resulting index file and lets the user resolve + * the merge conflicts using standard tools for three-way merge. + * + * This function is just to set-up such an arrangement, and the + * actual merge uses threeway_merge() function. + */ +static void setup_emu23(void) +{ + /* stage0 contains I, stage1 H, stage2 M. + * move stage2 to stage3, and create stage2 entries + * by scanning stage0 and stage1 entries. + */ + int i, namelen, size; + struct cache_entry *ce, *stage2; + + for (i = 0; i < active_nr; i++) { + ce = active_cache[i]; + if (ce_stage(ce) != 2) + continue; + /* hoist them up to stage 3 */ + namelen = ce_namelen(ce); + ce->ce_flags = create_ce_flags(namelen, 3); + } + + for (i = 0; i < active_nr; i++) { + ce = active_cache[i]; + if (ce_stage(ce) > 1) + continue; + namelen = ce_namelen(ce); + size = cache_entry_size(namelen); + stage2 = xmalloc(size); + memcpy(stage2, ce, size); + stage2->ce_flags = create_ce_flags(namelen, 2); + if (add_cache_entry(stage2, ADD_CACHE_OK_TO_ADD) < 0) + die("cannot merge index and our head tree"); + + /* We are done with this name, so skip to next name */ + while (i < active_nr && + ce_namelen(active_cache[i]) == namelen && + !memcmp(active_cache[i]->name, ce->name, namelen)) + i++; + i--; /* compensate for the loop control */ + } +} + +/* * One-way merge. * * The rule is: @@ -315,7 +367,7 @@ static struct cache_file cache_file; int main(int argc, char **argv) { - int i, newfd, merge, reset; + int i, newfd, merge, reset, emu23; unsigned char sha1[20]; newfd = hold_index_file_for_update(&cache_file, get_index_file()); @@ -324,6 +376,7 @@ int main(int argc, char **argv) merge = 0; reset = 0; + emu23 = 0; for (i = 1; i < argc; i++) { const char *arg = argv[i]; @@ -335,7 +388,7 @@ int main(int argc, char **argv) /* This differs from "-m" in that we'll silently ignore unmerged entries */ if (!strcmp(arg, "--reset")) { - if (stage || merge) + if (stage || merge || emu23) usage(read_tree_usage); reset = 1; merge = 1; @@ -345,7 +398,7 @@ int main(int argc, char **argv) /* "-m" stands for "merge", meaning we start in stage 1 */ if (!strcmp(arg, "-m")) { - if (stage || merge) + if (stage || merge || emu23) usage(read_tree_usage); if (read_cache_unmerged()) die("you need to resolve your current index first"); @@ -353,6 +406,17 @@ int main(int argc, char **argv) merge = 1; continue; } + + /* "-emu23" uses 3-way merge logic to perform fast-forward */ + if (!strcmp(arg, "--emu23")) { + if (stage || merge || emu23) + usage(read_tree_usage); + if (read_cache_unmerged()) + die("you need to resolve your current index first"); + merge = emu23 = stage = 1; + continue; + } + if (get_sha1(arg, sha1) < 0) usage(read_tree_usage); if (stage > 3) @@ -369,9 +433,18 @@ int main(int argc, char **argv) [2] = twoway_merge, [3] = threeway_merge, }; + merge_fn_t fn; + if (stage < 2 || stage > 4) die("just how do you expect me to merge %d trees?", stage-1); - merge_cache(active_cache, active_nr, merge_function[stage-1]); + if (emu23 && stage != 3) + die("--emu23 takes only two trees"); + fn = merge_function[stage-1]; + if (stage == 3 && emu23) { + setup_emu23(); + fn = merge_function[3]; + } + merge_cache(active_cache, active_nr, fn); } if (write_cache(newfd, active_cache, active_nr) || commit_index_file(&cache_file)) |