reflog: make entry_byindex() and drop() git compliant

Passing 0 as the index now retrieves the most recent entry instead
of the oldest one.

1 files changed, 23 insertions, 18 deletions

diff --git a/src/reflog.c b/src/reflog.c
index 0e333aa6f..7b07c6a9f 100644
--- a/src/reflog.c
+++ b/src/reflog.c
@@ -291,8 +291,8 @@ success:
 int git_reflog_append(git_reflog *reflog, const git_oid *new_oid,
 				const git_signature *committer, const char *msg)
 {
-	int count;
 	git_reflog_entry *entry;
+	const git_reflog_entry *previous;
 	const char *newline;
 
 	assert(reflog && new_oid && committer);
@@ -319,16 +319,12 @@ int git_reflog_append(git_reflog *reflog, const git_oid *new_oid,
 		}
 	}
 
-	count = git_reflog_entrycount(reflog);
+	previous = git_reflog_entry_byindex(reflog, 0);
 
-	if (count == 0)
+	if (previous == NULL)
 		git_oid_fromstr(&entry->oid_old, GIT_OID_HEX_ZERO);
-	else {
-		const git_reflog_entry *previous;
-
-		previous = git_reflog_entry_byindex(reflog, count -1);
+	else
 		git_oid_cpy(&entry->oid_old, &previous->oid_cur);
-	}
 
 	git_oid_cpy(&entry->oid_cur, new_oid);
 
@@ -417,8 +413,16 @@ unsigned int git_reflog_entrycount(git_reflog *reflog)
 
 const git_reflog_entry * git_reflog_entry_byindex(git_reflog *reflog, size_t idx)
 {
+	int pos;
+
 	assert(reflog);
-	return git_vector_get(&reflog->entries, idx);
+
+	pos = git_reflog_entrycount(reflog) - (idx + 1);
+
+	if (pos < 0)
+		return NULL;
+
+	return git_vector_get(&reflog->entries, pos);
 }
 
 const git_oid * git_reflog_entry_oidold(const git_reflog_entry *entry)
@@ -447,7 +451,7 @@ char * git_reflog_entry_msg(const git_reflog_entry *entry)
 
 int git_reflog_drop(
 	git_reflog *reflog,
-	unsigned int idx,
+	size_t idx,
 	int rewrite_previous_entry)
 {
 	unsigned int entrycount;
@@ -457,30 +461,31 @@ int git_reflog_drop(
 
 	entrycount = git_reflog_entrycount(reflog);
 
-	if (idx >= entrycount)
+	entry = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx);
+
+	if (entry == NULL)
 		return GIT_ENOTFOUND;
 
-	entry = git_vector_get(&reflog->entries, idx);
 	reflog_entry_free(entry);
 
-	if (git_vector_remove(&reflog->entries, idx) < 0)
+	if (git_vector_remove(&reflog->entries, entrycount - (idx + 1)) < 0)
 		return -1;
 
 	if (!rewrite_previous_entry)
 		return 0;
 
 	/* No need to rewrite anything when removing the most recent entry */
-	if (idx == entrycount - 1)
+	if (idx == 0)
 		return 0;
 
-	/* There are no more entries in the log */
+	/* Have the latest entry just been dropped? */
 	if (entrycount == 1)
 		return 0;
 
-	entry = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx);
+	entry = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx - 1);
 
 	/* If the oldest entry has just been removed... */
-	if (idx == 0) {
+	if (idx == entrycount - 1) {
 		/* ...clear the oid_old member of the "new" oldest entry */
 		if (git_oid_fromstr(&entry->oid_old, GIT_OID_HEX_ZERO) < 0)
 			return -1;
@@ -488,7 +493,7 @@ int git_reflog_drop(
 		return 0;
 	}
 
-	previous = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx - 1);
+	previous = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx);
 	git_oid_cpy(&entry->oid_old, &previous->oid_cur);
 
 	return 0;