Subject: Re: [RFC PATCH v1 06/17] merge-index: libify merge_one_path() and merge_all()

From: Alban Gruin <[email-masked]>
Date: Sun, 12 Jul 2020 13:36:37 +0200 (CEST)

Hi Phillip,

Phillip Wood ([email-masked]) a écrit :

> Hi Alban
> 
> On 25/06/2020 13:19, Alban Gruin wrote:
> -%<-
> > diff --git a/merge-strategies.c b/merge-strategies.c
> > index 3a9fce9f22..f4c0b4acd6 100644
> > --- a/merge-strategies.c
> > +++ b/merge-strategies.c
> > @@ -1,6 +1,7 @@
> >  #include "cache.h"
> >  #include "dir.h"
> >  #include "merge-strategies.h"
> > +#include "run-command.h"
> >  #include "xdiff-interface.h"
> >  
> >  static int add_to_index_cacheinfo(struct index_state *istate,
> > @@ -189,3 +190,101 @@ int merge_strategies_one_file(struct repository *r,
> >  
> >  	return 0;
> >  }
> > +
> > +int merge_program_cb(const struct object_id *orig_blob,
> > +		     const struct object_id *our_blob,
> > +		     const struct object_id *their_blob, const char *path,
> > +		     unsigned int orig_mode, unsigned int our_mode, unsigned int their_mode,
> > +		     void *data)
> 
> Using void* is slightly unfortunate but it's needed later.
> 
> It would be nice to check if the program to run is git-merge-one-file
> and call the appropriate function instead in that case so all users of
> merge-index get the benefit of it being builtin. That probably wants to
> be done in cmd_merge_index() rather than here though.
> 

Dunno, I am not completely comfortable with changing a parameter that 
specifically describe a program, to a parameter that may be a program, 
except in one case where `merge-index' should lock the index, setup the 
worktree, and call a function instead.

Well, I say that, but implementing that behaviour is not that hard:

-- snip --
diff --git a/builtin/merge-index.c b/builtin/merge-index.c
index 6cb666cc78..19fff9a113 100644
--- a/builtin/merge-index.c
+++ b/builtin/merge-index.c
@@ -1,11 +1,15 @@
 #define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "builtin.h"
+#include "lockfile.h"
 #include "merge-strategies.h"
 
 int cmd_merge_index(int argc, const char **argv, const char *prefix)
 {
 	int i, force_file = 0, err = 0, one_shot = 0, quiet = 0;
 	const char *pgm;
+	void *data;
+	merge_cb merge_action;
+	struct lock_file lock = LOCK_INIT;
 
 	/* Without this we cannot rely on waitpid() to tell
 	 * what happened to our children.
@@ -26,7 +30,19 @@ int cmd_merge_index(int argc, const char **argv, const char *prefix)
 		quiet = 1;
 		i++;
 	}
+
 	pgm = argv[i++];
+	if (!strcmp(pgm, "git-merge-one-file")) {
+		merge_action = merge_one_file_cb;
+		data = (void *)the_repository;
+
+		setup_work_tree();
+		hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
+	} else {
+		merge_action = merge_program_cb;
+		data = (void *)pgm;
+	}
+
 	for (; i < argc; i++) {
 		const char *arg = argv[i];
 		if (!force_file && *arg == '-') {
@@ -36,13 +52,22 @@ int cmd_merge_index(int argc, const char **argv, const char *prefix)
 			}
 			if (!strcmp(arg, "-a")) {
 				err |= merge_all(&the_index, one_shot, quiet,
-						 merge_program_cb, (void *)pgm);
+						 merge_action, data);
 				continue;
 			}
 			die("git merge-index: unknown option %s", arg);
 		}
 		err |= merge_one_path(&the_index, one_shot, quiet, arg,
-				      merge_program_cb, (void *)pgm);
+				      merge_action, data);
+	}
+
+	if (merge_action == merge_one_file_cb) {
+		if (err) {
+			rollback_lock_file(&lock);
+			return err;
+		}
+
+		return write_locked_index(&the_index, &lock, COMMIT_LOCK);
 	}
 	return err;
 }
-- snap --

> > +{
> > +	char ownbuf[3][60] = {{0}};
> 
> I know this is copied from above but it would be better to use
> GIT_MAX_HEXSZ rather than 60
> 

Cheers,
Alban