@matheusbsbs / matheus-bagliano / commits / 838f9a1566

log: use true parents for diff when walking reflogs

The reflog walking logic (git log -g) replaces the true parent list with the preceding commit in the reflog. This results in bogus commit diffs when combined with options such as -p; the diff is against the reflog predecessor, not the parent of the commit. Save the true parents on the side, extending the functions from the previous commit. The diff logic picks them up and uses them to show the correct diffs. We do have to be somewhat careful about repeated calling of save_parents(), since the reflog may list a commit more than once. We now store (commit_list*)-1 to distinguish the "not saved yet" and "root commit" cases. This lets us preserve an empty parent list even if save_parents() is repeatedly called. Suggested-by: Jeff King <peff@peff.net> Signed-off-by: Thomas Rast <trast@inf.ethz.ch> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Thomas Rast committed Aug 3, 2013 at 12:36 UTC 838f9a15667cfefa9e645c26627ce81ce7599915

2 files changed +47 -3

revision.c

+25 -3

@@ -2848,6 +2848,7 @@ static struct commit *get_revision_1(struct rev_info *revs)

2848 free(entry);

2849

2850 if (revs->reflog_info) {

2851 + save_parents(revs, commit);

2852 fake_reflog_parent(revs->reflog_info, commit);

2853 commit->object.flags &= ~(ADDED | SEEN | SHOWN);

2854 }

@@ -3083,6 +3084,8 @@ void put_revision_mark(const struct rev_info *revs, const struct commit *commit)

3084

3085 define_commit_slab(saved_parents, struct commit_list *);

3086

3087 +#define EMPTY_PARENT_LIST ((struct commit_list *)-1)

3088 +

3089 void save_parents(struct rev_info *revs, struct commit *commit)

3090 {

3091 struct commit_list **pp;

@@ -3093,16 +3096,35 @@ void save_parents(struct rev_info *revs, struct commit *commit)

3096 }

3097

3098 pp = saved_parents_at(revs->saved_parents_slab, commit);

3096 - assert(*pp == NULL);

3097 - *pp = copy_commit_list(commit->parents);

3099 +

3100 + /*

3101 + * When walking with reflogs, we may visit the same commit

3102 + * several times: once for each appearance in the reflog.

3103 + *

3104 + * In this case, save_parents() will be called multiple times.

3105 + * We want to keep only the first set of parents. We need to

3106 + * store a sentinel value for an empty (i.e., NULL) parent

3107 + * list to distinguish it from a not-yet-saved list, however.

3108 + */

3109 + if (*pp)

3110 + return;

3111 + if (commit->parents)

3112 + *pp = copy_commit_list(commit->parents);

3113 + else

3114 + *pp = EMPTY_PARENT_LIST;

3115 }

3116

3117 struct commit_list *get_saved_parents(struct rev_info *revs, const struct commit *commit)

3118 {

3119 + struct commit_list *parents;

3120 +

3121 if (!revs->saved_parents_slab)

3122 return commit->parents;

3123

3105 - return *saved_parents_at(revs->saved_parents_slab, commit);

3124 + parents = *saved_parents_at(revs->saved_parents_slab, commit);

3125 + if (parents == EMPTY_PARENT_LIST)

3126 + return NULL;

3127 + return parents;

3128 }

3129

3130 void free_saved_parents(struct rev_info *revs)

t/t1411-reflog-show.sh

+22

@@ -144,4 +144,26 @@ test_expect_success 'empty reflog file' '

144 test_cmp expect actual

145 '

146

147 +# This guards against the alternative of showing the diffs vs. the

148 +# reflog ancestor. The reflog used is designed to list the commits

149 +# more than once, so as to exercise the corresponding logic.

150 +test_expect_success 'git log -g -p shows diffs vs. parents' '

151 + test_commit two &&

152 + git branch flipflop &&

153 + git update-ref refs/heads/flipflop -m flip1 HEAD^ &&

154 + git update-ref refs/heads/flipflop -m flop1 HEAD &&

155 + git update-ref refs/heads/flipflop -m flip2 HEAD^ &&

156 + git log -g -p flipflop >reflog &&

157 + grep -v ^Reflog reflog >actual &&

158 + git log -1 -p HEAD^ >log.one &&

159 + git log -1 -p HEAD >log.two &&

160 + (

161 + cat log.one; echo

162 + cat log.two; echo

163 + cat log.one; echo

164 + cat log.two

165 + ) >expect &&

166 + test_cmp expect actual

167 +'

168 +

169 test_done