thodg/libgit2

2018-03-16T11:18:02

blame_git: fix coalescing step never being executed Since blame has been imported from git.git and had its first share of refactorings in b6f60a4d9 (Clean up ported code, 2013-09-21), the code is actually not doing the coalescing step of the generated blame. While the code to do the coalescing does exist, it is never being called as the function `git_blame__like_git` will directly return from its `while (true)` loop. The function that was being imported from git.git was the `assign_blame` function from "builtin/blame.c" from 717d1462b (git-blame --incremental, 2007-01-28), which hasn't really changed much. Upon taking an initial look, one can seet hat `coalesce` is actually never getting called in `assign_blame`, as well, so one may assume that not calling `coalesce` by accident is actually the right thing. But it is not, as `coalesce` is being called ever since cee7f245d (git-pickaxe: blame rewritten., 2006-10-19) after the blame has been done in the caller of `assign_blame`. Thus we can conclude the code of libgit2 is actually buggy since forever. To fix the issue, simply break out of the loop instead of doing a direct return. Note that this does not alter behaviour in any way visible to our tests, which is unfortunate. But in order to not diverge from what git.git does, I'd rather adapt to how it is being done upstream in order to avoid breaking certain edge cases than to just remove that code.

diff --git a/src/blame_git.c b/src/blame_git.c
index 3c221b3..302cd1e 100644
--- a/src/blame_git.c
+++ b/src/blame_git.c
@@ -623,6 +623,8 @@ static void coalesce(git_blame *blame)
 
 int git_blame__like_git(git_blame *blame, uint32_t opt)
 {
+	int error = 0;
+
 	while (true) {
 		git_blame__entry *ent;
 		git_blame__origin *suspect = NULL;
@@ -632,13 +634,13 @@ int git_blame__like_git(git_blame *blame, uint32_t opt)
 			if (!ent->guilty)
 				suspect = ent->suspect;
 		if (!suspect)
-			return 0; /* all done */
+			break;
 
 		/* We'll use this suspect later in the loop, so hold on to it for now. */
 		origin_incref(suspect);
 
-		if (pass_blame(blame, suspect, opt) < 0)
-			return -1;
+		if ((error = pass_blame(blame, suspect, opt)) < 0)
+			break;
 
 		/* Take responsibility for the remaining entries */
 		for (ent = blame->ent; ent; ent = ent->next) {
@@ -652,9 +654,10 @@ int git_blame__like_git(git_blame *blame, uint32_t opt)
 		origin_decref(suspect);
 	}
 
-	coalesce(blame);
+	if (!error)
+		coalesce(blame);
 
-	return 0;
+	return error;
 }
 
 void git_blame__free_entry(git_blame__entry *ent)