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4.6 Exercise 6

From git repo, checkout revision 0194c9ad72 and merge revision aa46a0da30. There will be a CB in ref-filter.c:

Listing 4.14:Exercise 6 - CB in ref-filter.c
843<<<<<<< HEAD 
844/* 
845 * Given an object name, read the object data and size, and return a 
846 * "struct object".  If the object data we are returning is also borrowed 
847 * by the "struct object" representation, set *eaten as well---it is a 
848 * signal from parse_object_buffer to us not to free the buffer. 
849 */ 
850static void *get_obj(const struct object_id *oid, struct object **obj, unsigned long *sz, int *eaten) 
851{ 
852        enum object_type type; 
853        void *buf = read_object_file(oid, &type, sz); 
854 
855        if (buf) 
856                *obj = parse_object_buffer(the_repository, oid, type, *sz, 
857                                           buf, eaten); 
858        else 
859                *obj = NULL; 
860        return buf; 
861} 
862 
863||||||| e3331758f1 
864/* 
865 * Given an object name, read the object data and size, and return a 
866 * "struct object".  If the object data we are returning is also borrowed 
867 * by the "struct object" representation, set *eaten as well---it is a 
868 * signal from parse_object_buffer to us not to free the buffer. 
869 */ 
870static void *get_obj(const struct object_id *oid, struct object **obj, unsigned long *sz, int *eaten) 
871{ 
872        enum object_type type; 
873        void *buf = read_object_file(oid, &type, sz); 
874 
875        if (buf) 
876                *obj = parse_object_buffer(oid, type, *sz, buf, eaten); 
877        else 
878                *obj = NULL; 
879        return buf; 
880} 
881 
882======= 
883>>>>>>> aa46a0da30

It’s a conflict ouf of deleted code.

dMU

Modified the call to parse_object_buffer() to have the_repository as the first argument on line 856.

dML

Deleted the whole section of code.

Resolution

Should we delete the whole CB and move on with our lives? I really hope you had a Pavlov reflex saying NOOOOO!!!!! Good! All the hard work is paying off. We need to find out what happened with that code. The hard way is to find out in what revision that code was deleted to see if it was moved. First, we do the git blame –reverse:

Listing 4.15:Exercise 6 - git blame –reverse on ref-filter.c
. 
. 
. 
04f6ee1a58e  807)       if (buf) 
04f6ee1a58e  808)               *obj = parse_object_buffer(oid, type, *sz, buf, eaten); 
04f6ee1a58e  809)       else 
04f6ee1a58e  810)               *obj = NULL;

The last revision when the line was present was on 04f6ee1a58e. Let’s check what follows that revision:

Listing 4.16:Exercise 6 - git log –oneline on ref-filter.c
$ git log --oneline --graph 04f6ee1a58e..aa46a0da30 -- ref-filter.c 
* aa46a0da30 ref-filter: use oid_object_info() to get object 
* e2255179f6 ref-filter: merge get_obj and get_object

And checking those two revisions we find that the code was apparently deleted in e2255179f6.

Listing 4.17:Exercise 6 - git show e2255179f6
843$ git show e2255179f6 --pretty= 
844diff --git a/ref-filter.c b/ref-filter.c 
845index 8db7ca95b1..2b401a17c4 100644 
846--- a/ref-filter.c 
847+++ b/ref-filter.c 
848@@ -797,24 +797,6 @@ int verify_ref_format(struct ref_format *format) 
849        return 0; 
850 } 
851 
852-/* 
853- * Given an object name, read the object data and size, and return a 
854- * "struct object".  If the object data we are returning is also borrowed 
855- * by the "struct object" representation, set *eaten as well---it is a 
856- * signal from parse_object_buffer to us not to free the buffer. 
857- */ 
858-static void *get_obj(const struct object_id *oid, struct object **obj, unsigned long *sz, int *eaten) 
859-{ 
860-       enum object_type type; 
861-       void *buf = read_object_file(oid, &type, sz); 
862- 
863-       if (buf) 
864-               *obj = parse_object_buffer(oid, type, *sz, buf, eaten); 
865-       else 
866-               *obj = NULL; 
867-       return buf; 
868-} 
869- 
870 static int grab_objectname(const char *name, const struct object_id *oid, 
871                           struct atom_value *v, struct used_atom *atom) 
872 { 
873@@ -1437,21 +1419,25 @@ static const char *get_refname(struct used_atom *atom, struct ref_array_item *re 
874 } 
875 
876 static int get_object(struct ref_array_item *ref, const struct object_id *oid, 
877-                      int deref, struct object **obj, struct strbuf *err) 
878+                     int deref, struct object **obj, struct strbuf *err) 
879 { 
880        /* parse_object_buffer() will set eaten to 0 if free() will be needed */ 
881        int eaten = 1; 
882        int ret = 0; 
883        unsigned long size; 
884-       void *buf = get_obj(oid, obj, &size, &eaten); 
885+       enum object_type type; 
886+       void *buf = read_object_file(oid, &type, &size); 
887        if (!buf) 
888                ret = strbuf_addf_ret(err, -1, _("missing object %s for %s"), 
889                                      oid_to_hex(oid), ref->refname); 
890-       else if (!*obj) 
891-               ret = strbuf_addf_ret(err, -1, _("parse_object_buffer failed on %s for %s"), 
892-                                     oid_to_hex(oid), ref->refname); 
893-       else 
894-               grab_values(ref->value, deref, *obj, buf, size); 
895+       else { 
896+               *obj = parse_object_buffer(oid, type, size, buf, &eaten); 
897+               if (!*obj) 
898+                       ret = strbuf_addf_ret(err, -1, _("parse_object_buffer failed on %s for %s"), 
899+                                             oid_to_hex(oid), ref->refname); 
900+               else 
901+                       grab_values(ref->value, deref, *obj, buf, size); 
902+       } 
903        if (!eaten) 
904                free(buf); 
905        return ret;

In the second hunk we can see that the call to parse_object_buffer was added back. In other words, the call was moved, and that call is still in our conflicted file, in line 1520:

Listing 4.18:Exercise 6 - section of ref-filter.c
1519        if (oi->info.contentp) { 
1520                *obj = parse_object_buffer(&oi->oid, oi->type, oi->size, oi->content, &eaten); 
1521                if (!obj) { 
1522                        if (!eaten) 
1523                                free(oi->content); 
1524                        return strbuf_addf_ret(err, -1, _("parse_object_buffer failed on %s for %s"), 
1525                                               oid_to_hex(&oi->oid), ref->refname); 
1526                } 
1527                grab_values(ref->value, deref, *obj, oi->content, oi->size); 
1528        }

So all we need to do, as our dMU requests, is to add the_repository as the first argument to the call on line 1520:

Listing 4.19:Exercise 6 - adjusted section of ref-filter.c
1519        if (oi->info.contentp) { 
1520                *obj = parse_object_buffer(the_repository, &oi->oid, oi->type, oi->size, oi->content, &eaten); 
1521                if (!obj) { 
1522                        if (!eaten) 
1523                                free(oi->content); 
1524                        return strbuf_addf_ret(err, -1, _("parse_object_buffer failed on %s for %s"), 
1525                                               oid_to_hex(&oi->oid), ref->refname); 
1526                } 
1527                grab_values(ref->value, deref, *obj, oi->content, oi->size); 
1528        }

We remove the original CB:

Listing 4.20:Exercise 6 - remove CB in ref-filter.c
840        return 0; 
841} 
842 
843static int grab_objectname(const char *name, const struct object_id *oid, 
844                           struct atom_value *v, struct used_atom *atom) 
845{

And if you now check differences with revision c83149ace6, you should get none.

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