reflog_expire(): new function in the reference API

Move expire_reflog() into refs.c and rename it to reflog_expire().
Turn the three policy functions into function pointers that are passed
into reflog_expire(). Add function prototypes and documentation to
refs.h.

[jc: squashed in $gmane/261582, drop "extern" in function definition]

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Stefan Beller <sbeller@google.com>
Tweaked-by: Ramsay Jones
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 129 insertions, 0 deletions

diff --git a/refs.c b/refs.c
index 150c980247..4b27a1ba8e 100644
--- a/refs.c
+++ b/refs.c
@@ -3943,3 +3943,132 @@ int ref_is_hidden(const char *refname)
 	}
 	return 0;
 }
+
+struct expire_reflog_cb {
+	unsigned int flags;
+	reflog_expiry_should_prune_fn *should_prune_fn;
+	void *policy_cb;
+	FILE *newlog;
+	unsigned char last_kept_sha1[20];
+};
+
+static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
+			     const char *email, unsigned long timestamp, int tz,
+			     const char *message, void *cb_data)
+{
+	struct expire_reflog_cb *cb = cb_data;
+	struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
+
+	if (cb->flags & EXPIRE_REFLOGS_REWRITE)
+		osha1 = cb->last_kept_sha1;
+
+	if ((*cb->should_prune_fn)(osha1, nsha1, email, timestamp, tz,
+				   message, policy_cb)) {
+		if (!cb->newlog)
+			printf("would prune %s", message);
+		else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
+			printf("prune %s", message);
+	} else {
+		if (cb->newlog) {
+			char sign = (tz < 0) ? '-' : '+';
+			int zone = (tz < 0) ? (-tz) : tz;
+			fprintf(cb->newlog, "%s %s %s %lu %c%04d\t%s",
+				sha1_to_hex(osha1), sha1_to_hex(nsha1),
+				email, timestamp, sign, zone,
+				message);
+			hashcpy(cb->last_kept_sha1, nsha1);
+		}
+		if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
+			printf("keep %s", message);
+	}
+	return 0;
+}
+
+int reflog_expire(const char *refname, const unsigned char *sha1,
+		 unsigned int flags,
+		 reflog_expiry_prepare_fn prepare_fn,
+		 reflog_expiry_should_prune_fn should_prune_fn,
+		 reflog_expiry_cleanup_fn cleanup_fn,
+		 void *policy_cb_data)
+{
+	static struct lock_file reflog_lock;
+	struct expire_reflog_cb cb;
+	struct ref_lock *lock;
+	char *log_file;
+	int status = 0;
+
+	memset(&cb, 0, sizeof(cb));
+	cb.flags = flags;
+	cb.policy_cb = policy_cb_data;
+	cb.should_prune_fn = should_prune_fn;
+
+	/*
+	 * The reflog file is locked by holding the lock on the
+	 * reference itself, plus we might need to update the
+	 * reference if --updateref was specified:
+	 */
+	lock = lock_any_ref_for_update(refname, sha1, 0, NULL);
+	if (!lock)
+		return error("cannot lock ref '%s'", refname);
+	if (!reflog_exists(refname)) {
+		unlock_ref(lock);
+		return 0;
+	}
+
+	log_file = git_pathdup("logs/%s", refname);
+	if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
+		/*
+		 * Even though holding $GIT_DIR/logs/$reflog.lock has
+		 * no locking implications, we use the lock_file
+		 * machinery here anyway because it does a lot of the
+		 * work we need, including cleaning up if the program
+		 * exits unexpectedly.
+		 */
+		if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
+			struct strbuf err = STRBUF_INIT;
+			unable_to_lock_message(log_file, errno, &err);
+			error("%s", err.buf);
+			strbuf_release(&err);
+			goto failure;
+		}
+		cb.newlog = fdopen_lock_file(&reflog_lock, "w");
+		if (!cb.newlog) {
+			error("cannot fdopen %s (%s)",
+			      reflog_lock.filename.buf, strerror(errno));
+			goto failure;
+		}
+	}
+
+	(*prepare_fn)(refname, sha1, cb.policy_cb);
+	for_each_reflog_ent(refname, expire_reflog_ent, &cb);
+	(*cleanup_fn)(cb.policy_cb);
+
+	if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
+		if (close_lock_file(&reflog_lock)) {
+			status |= error("couldn't write %s: %s", log_file,
+					strerror(errno));
+		} else if ((flags & EXPIRE_REFLOGS_UPDATE_REF) &&
+			(write_in_full(lock->lock_fd,
+				sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
+			 write_str_in_full(lock->lock_fd, "\n") != 1 ||
+			 close_ref(lock) < 0)) {
+			status |= error("couldn't write %s",
+					lock->lk->filename.buf);
+			rollback_lock_file(&reflog_lock);
+		} else if (commit_lock_file(&reflog_lock)) {
+			status |= error("unable to commit reflog '%s' (%s)",
+					log_file, strerror(errno));
+		} else if ((flags & EXPIRE_REFLOGS_UPDATE_REF) && commit_ref(lock)) {
+			status |= error("couldn't set %s", lock->ref_name);
+		}
+	}
+	free(log_file);
+	unlock_ref(lock);
+	return status;
+
+ failure:
+	rollback_lock_file(&reflog_lock);
+	free(log_file);
+	unlock_ref(lock);
+	return -1;
+}