src/reflog.c - third_party/libgit2 - Git at Google

 /*
  * Copyright (C) the libgit2 contributors. All rights reserved.
  *
  * This file is part of libgit2, distributed under the GNU GPL v2 with
  * a Linking Exception. For full terms see the included COPYING file.
  */

 #include "reflog.h"
 #include "repository.h"
 #include "filebuf.h"
 #include "signature.h"

 static int reflog_init(git_reflog **reflog, const git_reference *ref)
 {
 	git_reflog *log;

 	*reflog = NULL;

 	log = git__calloc(1, sizeof(git_reflog));
 	GITERR_CHECK_ALLOC(log);

 	log->ref_name = git__strdup(ref->name);
 	GITERR_CHECK_ALLOC(log->ref_name);

 	if (git_vector_init(&log->entries, 0, NULL) < 0) {
 		git__free(log->ref_name);
 		git__free(log);
 		return -1;
 	}

 	log->owner = git_reference_owner(ref);
 	*reflog = log;

 	return 0;
 }

 static int serialize_reflog_entry(
 	git_buf *buf,
 	const git_oid *oid_old,
 	const git_oid *oid_new,
 	const git_signature *committer,
 	const char *msg)
 {
 	char raw_old[GIT_OID_HEXSZ+1];
 	char raw_new[GIT_OID_HEXSZ+1];

 	git_oid_tostr(raw_old, GIT_OID_HEXSZ+1, oid_old);
 	git_oid_tostr(raw_new, GIT_OID_HEXSZ+1, oid_new);

 	git_buf_clear(buf);

 	git_buf_puts(buf, raw_old);
 	git_buf_putc(buf, ' ');
 	git_buf_puts(buf, raw_new);

 	git_signature__writebuf(buf, " ", committer);

 	/* drop trailing LF */
 	git_buf_rtrim(buf);

 	if (msg) {
 		git_buf_putc(buf, '\t');
 		git_buf_puts(buf, msg);
 	}

 	git_buf_putc(buf, '\n');

 	return git_buf_oom(buf);
 }

 static int reflog_entry_new(git_reflog_entry **entry)
 {
 	git_reflog_entry *e;

 	assert(entry);

 	e = git__malloc(sizeof(git_reflog_entry));
 	GITERR_CHECK_ALLOC(e);

 	memset(e, 0, sizeof(git_reflog_entry));

 	*entry = e;

 	return 0;
 }

 static void reflog_entry_free(git_reflog_entry *entry)
 {
 	git_signature_free(entry->committer);

 	git__free(entry->msg);
 	git__free(entry);
 }

 static int reflog_parse(git_reflog *log, const char *buf, size_t buf_size)
 {
 	const char *ptr;
 	git_reflog_entry *entry;

 #define seek_forward(_increase) do { \
 	if (_increase >= buf_size) { \
 		giterr_set(GITERR_INVALID, "Ran out of data while parsing reflog"); \
 		goto fail; \
 	} \
 	buf += _increase; \
 	buf_size -= _increase; \
 	} while (0)

 	while (buf_size > GIT_REFLOG_SIZE_MIN) {
 		if (reflog_entry_new(&entry) < 0)
 			return -1;

 		entry->committer = git__malloc(sizeof(git_signature));
 		GITERR_CHECK_ALLOC(entry->committer);

 		if (git_oid_fromstrn(&entry->oid_old, buf, GIT_OID_HEXSZ) < 0)
 			goto fail;
 		seek_forward(GIT_OID_HEXSZ + 1);

 		if (git_oid_fromstrn(&entry->oid_cur, buf, GIT_OID_HEXSZ) < 0)
 			goto fail;
 		seek_forward(GIT_OID_HEXSZ + 1);

 		ptr = buf;

 		/* Seek forward to the end of the signature. */
 		while (*buf && *buf != '\t' && *buf != '\n')
 			seek_forward(1);

 		if (git_signature__parse(entry->committer, &ptr, buf + 1, NULL, *buf) < 0)
 			goto fail;

 		if (*buf == '\t') {
 			/* We got a message. Read everything till we reach LF. */
 			seek_forward(1);
 			ptr = buf;

 			while (*buf && *buf != '\n')
 				seek_forward(1);

 			entry->msg = git__strndup(ptr, buf - ptr);
 			GITERR_CHECK_ALLOC(entry->msg);
 		} else
 			entry->msg = NULL;

 		while (*buf && *buf == '\n' && buf_size > 1)
 			seek_forward(1);

 		if (git_vector_insert(&log->entries, entry) < 0)
 			goto fail;
 	}

 	return 0;

 #undef seek_forward

 fail:
 	if (entry)
 		reflog_entry_free(entry);

 	return -1;
 }

 void git_reflog_free(git_reflog *reflog)
 {
 	size_t i;
 	git_reflog_entry *entry;

 	if (reflog == NULL)
 		return;

 	for (i=0; i < reflog->entries.length; i++) {
 		entry = git_vector_get(&reflog->entries, i);

 		reflog_entry_free(entry);
 	}

 	git_vector_free(&reflog->entries);
 	git__free(reflog->ref_name);
 	git__free(reflog);
 }

 static int retrieve_reflog_path(git_buf *path, const git_reference *ref)
 {
 	return git_buf_join_n(path, '/', 3,
 		git_reference_owner(ref)->path_repository, GIT_REFLOG_DIR, ref->name);
 }

 static int create_new_reflog_file(const char *filepath)
 {
 	int fd, error;

 	if ((error = git_futils_mkpath2file(filepath, GIT_REFLOG_DIR_MODE)) < 0)
 		return error;

 	if ((fd = p_open(filepath,
 			O_WRONLY | O_CREAT | O_TRUNC,
 			GIT_REFLOG_FILE_MODE)) < 0)
 		return -1;

 	return p_close(fd);
 }

 int git_reflog_read(git_reflog **reflog, const git_reference *ref)
 {
 	int error = -1;
 	git_buf log_path = GIT_BUF_INIT;
 	git_buf log_file = GIT_BUF_INIT;
 	git_reflog *log = NULL;

 	assert(reflog && ref);

 	*reflog = NULL;

 	if (reflog_init(&log, ref) < 0)
 		return -1;

 	if (retrieve_reflog_path(&log_path, ref) < 0)
 		goto cleanup;

 	error = git_futils_readbuffer(&log_file, git_buf_cstr(&log_path));
 	if (error < 0 && error != GIT_ENOTFOUND)
 		goto cleanup;

 	if ((error == GIT_ENOTFOUND) &&
 		((error = create_new_reflog_file(git_buf_cstr(&log_path))) < 0))
 		goto cleanup;

 	if ((error = reflog_parse(log,
 		git_buf_cstr(&log_file), git_buf_len(&log_file))) < 0)
 		goto cleanup;

 	*reflog = log;
 	goto success;

 cleanup:
 	git_reflog_free(log);

 success:
 	git_buf_free(&log_file);
 	git_buf_free(&log_path);

 	return error;
 }

 int git_reflog_write(git_reflog *reflog)
 {
 	int error = -1;
 	unsigned int i;
 	git_reflog_entry *entry;
 	git_buf log_path = GIT_BUF_INIT;
 	git_buf log = GIT_BUF_INIT;
 	git_filebuf fbuf = GIT_FILEBUF_INIT;

 	assert(reflog);

 	if (git_buf_join_n(&log_path, '/', 3,
 		git_repository_path(reflog->owner), GIT_REFLOG_DIR, reflog->ref_name) < 0)
 		return -1;

 	if (!git_path_isfile(git_buf_cstr(&log_path))) {
 		giterr_set(GITERR_INVALID,
 			"Log file for reference '%s' doesn't exist.", reflog->ref_name);
 		goto cleanup;
 	}

 	if ((error = git_filebuf_open(&fbuf, git_buf_cstr(&log_path), 0)) < 0)
 		goto cleanup;

 	git_vector_foreach(&reflog->entries, i, entry) {
 		if (serialize_reflog_entry(&log, &(entry->oid_old), &(entry->oid_cur), entry->committer, entry->msg) < 0)
 			goto cleanup;

 		if ((error = git_filebuf_write(&fbuf, log.ptr, log.size)) < 0)
 			goto cleanup;
 	}

 	error = git_filebuf_commit(&fbuf, GIT_REFLOG_FILE_MODE);
 	goto success;

 cleanup:
 	git_filebuf_cleanup(&fbuf);

 success:
 	git_buf_free(&log);
 	git_buf_free(&log_path);
 	return error;
 }

 int git_reflog_append(git_reflog *reflog, const git_oid *new_oid,
 				const git_signature *committer, const char *msg)
 {
 	git_reflog_entry *entry;
 	const git_reflog_entry *previous;
 	const char *newline;

 	assert(reflog && new_oid && committer);

 	if (reflog_entry_new(&entry) < 0)
 		return -1;

 	if ((entry->committer = git_signature_dup(committer)) == NULL)
 		goto cleanup;

 	if (msg != NULL) {
 		if ((entry->msg = git__strdup(msg)) == NULL)
 			goto cleanup;

 		newline = strchr(msg, '\n');

 		if (newline) {
 			if (newline[1] != '\0') {
 				giterr_set(GITERR_INVALID, "Reflog message cannot contain newline");
 				goto cleanup;
 			}

 			entry->msg[newline - msg] = '\0';
 		}
 	}

 	previous = git_reflog_entry_byindex(reflog, 0);

 	if (previous == NULL)
 		git_oid_fromstr(&entry->oid_old, GIT_OID_HEX_ZERO);
 	else
 		git_oid_cpy(&entry->oid_old, &previous->oid_cur);

 	git_oid_cpy(&entry->oid_cur, new_oid);

 	if (git_vector_insert(&reflog->entries, entry) < 0)
 		goto cleanup;

 	return 0;

 cleanup:
 	reflog_entry_free(entry);
 	return -1;
 }

 int git_reflog_rename(git_reference *ref, const char *new_name)
 {
 	int error = 0, fd;
 	git_buf old_path = GIT_BUF_INIT;
 	git_buf new_path = GIT_BUF_INIT;
 	git_buf temp_path = GIT_BUF_INIT;
 	git_buf normalized = GIT_BUF_INIT;

 	assert(ref && new_name);

 	if ((error = git_reference__normalize_name(
 		&normalized, new_name, GIT_REF_FORMAT_ALLOW_ONELEVEL)) < 0)
 			return error;

 	if (git_buf_joinpath(&temp_path, git_reference_owner(ref)->path_repository, GIT_REFLOG_DIR) < 0)
 		return -1;

 	if (git_buf_joinpath(&old_path, git_buf_cstr(&temp_path), ref->name) < 0)
 		return -1;

 	if (git_buf_joinpath(&new_path, git_buf_cstr(&temp_path), git_buf_cstr(&normalized)) < 0)
 		return -1;

 	/*
 	 * Move the reflog to a temporary place. This two-phase renaming is required
 	 * in order to cope with funny renaming use cases when one tries to move a reference
 	 * to a partially colliding namespace:
 	 *  - a/b -> a/b/c
 	 *  - a/b/c/d -> a/b/c
 	 */
 	if (git_buf_joinpath(&temp_path, git_buf_cstr(&temp_path), "temp_reflog") < 0)
 		return -1;

 	if ((fd = git_futils_mktmp(&temp_path, git_buf_cstr(&temp_path))) < 0) {
 		error = -1;
 		goto cleanup;
 	}

 	p_close(fd);

 	if (p_rename(git_buf_cstr(&old_path), git_buf_cstr(&temp_path)) < 0) {
 		giterr_set(GITERR_OS, "Failed to rename reflog for %s", new_name);
 		error = -1;
 		goto cleanup;
 	}

 	if (git_path_isdir(git_buf_cstr(&new_path)) &&
 		(git_futils_rmdir_r(git_buf_cstr(&new_path), NULL, GIT_RMDIR_SKIP_NONEMPTY) < 0)) {
 		error = -1;
 		goto cleanup;
 	}

 	if (git_futils_mkpath2file(git_buf_cstr(&new_path), GIT_REFLOG_DIR_MODE) < 0) {
 		error = -1;
 		goto cleanup;
 	}

 	if (p_rename(git_buf_cstr(&temp_path), git_buf_cstr(&new_path)) < 0) {
 		giterr_set(GITERR_OS, "Failed to rename reflog for %s", new_name);
 		error = -1;
 	}

 cleanup:
 	git_buf_free(&temp_path);
 	git_buf_free(&old_path);
 	git_buf_free(&new_path);
 	git_buf_free(&normalized);

 	return error;
 }

 int git_reflog_delete(git_reference *ref)
 {
 	int error;
 	git_buf path = GIT_BUF_INIT;

 	error = retrieve_reflog_path(&path, ref);

 	if (!error && git_path_exists(path.ptr))
 		error = p_unlink(path.ptr);

 	git_buf_free(&path);

 	return error;
 }

 size_t git_reflog_entrycount(git_reflog *reflog)
 {
 	assert(reflog);
 	return reflog->entries.length;
 }

 GIT_INLINE(size_t) reflog_inverse_index(size_t idx, size_t total)
 {
 	return (total - 1) - idx;
 }

 const git_reflog_entry * git_reflog_entry_byindex(git_reflog *reflog, size_t idx)
 {
 	assert(reflog);

 	if (idx >= reflog->entries.length)
 		return NULL;

 	return git_vector_get(
 		&reflog->entries, reflog_inverse_index(idx, reflog->entries.length));
 }

 const git_oid * git_reflog_entry_id_old(const git_reflog_entry *entry)
 {
 	assert(entry);
 	return &entry->oid_old;
 }

 const git_oid * git_reflog_entry_id_new(const git_reflog_entry *entry)
 {
 	assert(entry);
 	return &entry->oid_cur;
 }

 const git_signature * git_reflog_entry_committer(const git_reflog_entry *entry)
 {
 	assert(entry);
 	return entry->committer;
 }

 const char * git_reflog_entry_message(const git_reflog_entry *entry)
 {
 	assert(entry);
 	return entry->msg;
 }

 int git_reflog_drop(
 	git_reflog *reflog,
 	size_t idx,
 	int rewrite_previous_entry)
 {
 	size_t entrycount;
 	git_reflog_entry *entry, *previous;

 	assert(reflog);

 	entrycount = git_reflog_entrycount(reflog);

 	entry = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx);

 	if (entry == NULL) {
 		giterr_set(GITERR_REFERENCE, "No reflog entry at index "PRIuZ, idx);
 		return GIT_ENOTFOUND;
 	}

 	reflog_entry_free(entry);

 	if (git_vector_remove(
 			&reflog->entries, reflog_inverse_index(idx, entrycount)) < 0)
 		return -1;

 	if (!rewrite_previous_entry)
 		return 0;

 	/* No need to rewrite anything when removing the most recent entry */
 	if (idx == 0)
 		return 0;

 	/* Have the latest entry just been dropped? */
 	if (entrycount == 1)
 		return 0;

 	entry = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx - 1);

 	/* If the oldest entry has just been removed... */
 	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;

 		return 0;
 	}

 	previous = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx);
 	git_oid_cpy(&entry->oid_old, &previous->oid_cur);

 	return 0;
 }
	/*
	* Copyright (C) the libgit2 contributors. All rights reserved.
	*
	* This file is part of libgit2, distributed under the GNU GPL v2 with
	* a Linking Exception. For full terms see the included COPYING file.
	*/

	#include "reflog.h"
	#include "repository.h"
	#include "filebuf.h"
	#include "signature.h"

	static int reflog_init(git_reflog *reflog, const git_reference ref)
	{
	git_reflog *log;

	*reflog = NULL;

	log = git__calloc(1, sizeof(git_reflog));
	GITERR_CHECK_ALLOC(log);

	log->ref_name = git__strdup(ref->name);
	GITERR_CHECK_ALLOC(log->ref_name);

	if (git_vector_init(&log->entries, 0, NULL) < 0) {
	git__free(log->ref_name);
	git__free(log);
	return -1;
	}

	log->owner = git_reference_owner(ref);
	*reflog = log;

	return 0;
	}

	static int serialize_reflog_entry(
	git_buf *buf,
	const git_oid *oid_old,
	const git_oid *oid_new,
	const git_signature *committer,
	const char *msg)
	{
	char raw_old[GIT_OID_HEXSZ+1];
	char raw_new[GIT_OID_HEXSZ+1];

	git_oid_tostr(raw_old, GIT_OID_HEXSZ+1, oid_old);
	git_oid_tostr(raw_new, GIT_OID_HEXSZ+1, oid_new);

	git_buf_clear(buf);

	git_buf_puts(buf, raw_old);
	git_buf_putc(buf, ' ');
	git_buf_puts(buf, raw_new);

	git_signature__writebuf(buf, " ", committer);

	/* drop trailing LF */
	git_buf_rtrim(buf);

	if (msg) {
	git_buf_putc(buf, '\t');
	git_buf_puts(buf, msg);
	}

	git_buf_putc(buf, '\n');

	return git_buf_oom(buf);
	}

	static int reflog_entry_new(git_reflog_entry **entry)
	{
	git_reflog_entry *e;

	assert(entry);

	e = git__malloc(sizeof(git_reflog_entry));
	GITERR_CHECK_ALLOC(e);

	memset(e, 0, sizeof(git_reflog_entry));

	*entry = e;

	return 0;
	}

	static void reflog_entry_free(git_reflog_entry *entry)
	{
	git_signature_free(entry->committer);

	git__free(entry->msg);
	git__free(entry);
	}

	static int reflog_parse(git_reflog log, const char buf, size_t buf_size)
	{
	const char *ptr;
	git_reflog_entry *entry;

	#define seek_forward(_increase) do { \
	if (_increase >= buf_size) { \
	giterr_set(GITERR_INVALID, "Ran out of data while parsing reflog"); \
	goto fail; \
	} \
	buf += _increase; \
	buf_size -= _increase; \
	} while (0)

	while (buf_size > GIT_REFLOG_SIZE_MIN) {
	if (reflog_entry_new(&entry) < 0)
	return -1;

	entry->committer = git__malloc(sizeof(git_signature));
	GITERR_CHECK_ALLOC(entry->committer);

	if (git_oid_fromstrn(&entry->oid_old, buf, GIT_OID_HEXSZ) < 0)
	goto fail;
	seek_forward(GIT_OID_HEXSZ + 1);

	if (git_oid_fromstrn(&entry->oid_cur, buf, GIT_OID_HEXSZ) < 0)
	goto fail;
	seek_forward(GIT_OID_HEXSZ + 1);

	ptr = buf;

	/* Seek forward to the end of the signature. */
	while (buf && buf != '\t' && *buf != '\n')
	seek_forward(1);

	if (git_signature__parse(entry->committer, &ptr, buf + 1, NULL, *buf) < 0)
	goto fail;

	if (*buf == '\t') {
	/* We got a message. Read everything till we reach LF. */
	seek_forward(1);
	ptr = buf;

	while (buf && buf != '\n')
	seek_forward(1);

	entry->msg = git__strndup(ptr, buf - ptr);
	GITERR_CHECK_ALLOC(entry->msg);
	} else
	entry->msg = NULL;

	while (buf && buf == '\n' && buf_size > 1)
	seek_forward(1);

	if (git_vector_insert(&log->entries, entry) < 0)
	goto fail;
	}

	return 0;

	#undef seek_forward

	fail:
	if (entry)
	reflog_entry_free(entry);

	return -1;
	}

	void git_reflog_free(git_reflog *reflog)
	{
	size_t i;
	git_reflog_entry *entry;

	if (reflog == NULL)
	return;

	for (i=0; i < reflog->entries.length; i++) {
	entry = git_vector_get(&reflog->entries, i);

	reflog_entry_free(entry);
	}

	git_vector_free(&reflog->entries);
	git__free(reflog->ref_name);
	git__free(reflog);
	}

	static int retrieve_reflog_path(git_buf path, const git_reference ref)
	{
	return git_buf_join_n(path, '/', 3,
	git_reference_owner(ref)->path_repository, GIT_REFLOG_DIR, ref->name);
	}

	static int create_new_reflog_file(const char *filepath)
	{
	int fd, error;

	if ((error = git_futils_mkpath2file(filepath, GIT_REFLOG_DIR_MODE)) < 0)
	return error;

	if ((fd = p_open(filepath,
	O_WRONLY \| O_CREAT \| O_TRUNC,
	GIT_REFLOG_FILE_MODE)) < 0)
	return -1;

	return p_close(fd);
	}

	int git_reflog_read(git_reflog *reflog, const git_reference ref)
	{
	int error = -1;
	git_buf log_path = GIT_BUF_INIT;
	git_buf log_file = GIT_BUF_INIT;
	git_reflog *log = NULL;

	assert(reflog && ref);

	*reflog = NULL;

	if (reflog_init(&log, ref) < 0)
	return -1;

	if (retrieve_reflog_path(&log_path, ref) < 0)
	goto cleanup;

	error = git_futils_readbuffer(&log_file, git_buf_cstr(&log_path));
	if (error < 0 && error != GIT_ENOTFOUND)
	goto cleanup;

	if ((error == GIT_ENOTFOUND) &&
	((error = create_new_reflog_file(git_buf_cstr(&log_path))) < 0))
	goto cleanup;

	if ((error = reflog_parse(log,
	git_buf_cstr(&log_file), git_buf_len(&log_file))) < 0)
	goto cleanup;

	*reflog = log;
	goto success;

	cleanup:
	git_reflog_free(log);

	success:
	git_buf_free(&log_file);
	git_buf_free(&log_path);

	return error;
	}

	int git_reflog_write(git_reflog *reflog)
	{
	int error = -1;
	unsigned int i;
	git_reflog_entry *entry;
	git_buf log_path = GIT_BUF_INIT;
	git_buf log = GIT_BUF_INIT;
	git_filebuf fbuf = GIT_FILEBUF_INIT;

	assert(reflog);

	if (git_buf_join_n(&log_path, '/', 3,
	git_repository_path(reflog->owner), GIT_REFLOG_DIR, reflog->ref_name) < 0)
	return -1;

	if (!git_path_isfile(git_buf_cstr(&log_path))) {
	giterr_set(GITERR_INVALID,
	"Log file for reference '%s' doesn't exist.", reflog->ref_name);
	goto cleanup;
	}

	if ((error = git_filebuf_open(&fbuf, git_buf_cstr(&log_path), 0)) < 0)
	goto cleanup;

	git_vector_foreach(&reflog->entries, i, entry) {
	if (serialize_reflog_entry(&log, &(entry->oid_old), &(entry->oid_cur), entry->committer, entry->msg) < 0)
	goto cleanup;

	if ((error = git_filebuf_write(&fbuf, log.ptr, log.size)) < 0)
	goto cleanup;
	}

	error = git_filebuf_commit(&fbuf, GIT_REFLOG_FILE_MODE);
	goto success;

	cleanup:
	git_filebuf_cleanup(&fbuf);

	success:
	git_buf_free(&log);
	git_buf_free(&log_path);
	return error;
	}

	int git_reflog_append(git_reflog reflog, const git_oid new_oid,
	const git_signature committer, const char msg)
	{
	git_reflog_entry *entry;
	const git_reflog_entry *previous;
	const char *newline;

	assert(reflog && new_oid && committer);

	if (reflog_entry_new(&entry) < 0)
	return -1;

	if ((entry->committer = git_signature_dup(committer)) == NULL)
	goto cleanup;

	if (msg != NULL) {
	if ((entry->msg = git__strdup(msg)) == NULL)
	goto cleanup;

	newline = strchr(msg, '\n');

	if (newline) {
	if (newline[1] != '\0') {
	giterr_set(GITERR_INVALID, "Reflog message cannot contain newline");
	goto cleanup;
	}

	entry->msg[newline - msg] = '\0';
	}
	}

	previous = git_reflog_entry_byindex(reflog, 0);

	if (previous == NULL)
	git_oid_fromstr(&entry->oid_old, GIT_OID_HEX_ZERO);
	else
	git_oid_cpy(&entry->oid_old, &previous->oid_cur);

	git_oid_cpy(&entry->oid_cur, new_oid);

	if (git_vector_insert(&reflog->entries, entry) < 0)
	goto cleanup;

	return 0;

	cleanup:
	reflog_entry_free(entry);
	return -1;
	}

	int git_reflog_rename(git_reference ref, const char new_name)
	{
	int error = 0, fd;
	git_buf old_path = GIT_BUF_INIT;
	git_buf new_path = GIT_BUF_INIT;
	git_buf temp_path = GIT_BUF_INIT;
	git_buf normalized = GIT_BUF_INIT;

	assert(ref && new_name);

	if ((error = git_reference__normalize_name(
	&normalized, new_name, GIT_REF_FORMAT_ALLOW_ONELEVEL)) < 0)
	return error;

	if (git_buf_joinpath(&temp_path, git_reference_owner(ref)->path_repository, GIT_REFLOG_DIR) < 0)
	return -1;

	if (git_buf_joinpath(&old_path, git_buf_cstr(&temp_path), ref->name) < 0)
	return -1;

	if (git_buf_joinpath(&new_path, git_buf_cstr(&temp_path), git_buf_cstr(&normalized)) < 0)
	return -1;

	/*
	* Move the reflog to a temporary place. This two-phase renaming is required
	* in order to cope with funny renaming use cases when one tries to move a reference
	* to a partially colliding namespace:
	* - a/b -> a/b/c
	* - a/b/c/d -> a/b/c
	*/
	if (git_buf_joinpath(&temp_path, git_buf_cstr(&temp_path), "temp_reflog") < 0)
	return -1;

	if ((fd = git_futils_mktmp(&temp_path, git_buf_cstr(&temp_path))) < 0) {
	error = -1;
	goto cleanup;
	}

	p_close(fd);

	if (p_rename(git_buf_cstr(&old_path), git_buf_cstr(&temp_path)) < 0) {
	giterr_set(GITERR_OS, "Failed to rename reflog for %s", new_name);
	error = -1;
	goto cleanup;
	}

	if (git_path_isdir(git_buf_cstr(&new_path)) &&
	(git_futils_rmdir_r(git_buf_cstr(&new_path), NULL, GIT_RMDIR_SKIP_NONEMPTY) < 0)) {
	error = -1;
	goto cleanup;
	}

	if (git_futils_mkpath2file(git_buf_cstr(&new_path), GIT_REFLOG_DIR_MODE) < 0) {
	error = -1;
	goto cleanup;
	}

	if (p_rename(git_buf_cstr(&temp_path), git_buf_cstr(&new_path)) < 0) {
	giterr_set(GITERR_OS, "Failed to rename reflog for %s", new_name);
	error = -1;
	}

	cleanup:
	git_buf_free(&temp_path);
	git_buf_free(&old_path);
	git_buf_free(&new_path);
	git_buf_free(&normalized);

	return error;
	}

	int git_reflog_delete(git_reference *ref)
	{
	int error;
	git_buf path = GIT_BUF_INIT;

	error = retrieve_reflog_path(&path, ref);

	if (!error && git_path_exists(path.ptr))
	error = p_unlink(path.ptr);

	git_buf_free(&path);

	return error;
	}

	size_t git_reflog_entrycount(git_reflog *reflog)
	{
	assert(reflog);
	return reflog->entries.length;
	}

	GIT_INLINE(size_t) reflog_inverse_index(size_t idx, size_t total)
	{
	return (total - 1) - idx;
	}

	const git_reflog_entry * git_reflog_entry_byindex(git_reflog *reflog, size_t idx)
	{
	assert(reflog);

	if (idx >= reflog->entries.length)
	return NULL;

	return git_vector_get(
	&reflog->entries, reflog_inverse_index(idx, reflog->entries.length));
	}

	const git_oid * git_reflog_entry_id_old(const git_reflog_entry *entry)
	{
	assert(entry);
	return &entry->oid_old;
	}

	const git_oid * git_reflog_entry_id_new(const git_reflog_entry *entry)
	{
	assert(entry);
	return &entry->oid_cur;
	}

	const git_signature * git_reflog_entry_committer(const git_reflog_entry *entry)
	{
	assert(entry);
	return entry->committer;
	}

	const char * git_reflog_entry_message(const git_reflog_entry *entry)
	{
	assert(entry);
	return entry->msg;
	}

	int git_reflog_drop(
	git_reflog *reflog,
	size_t idx,
	int rewrite_previous_entry)
	{
	size_t entrycount;
	git_reflog_entry entry, previous;

	assert(reflog);

	entrycount = git_reflog_entrycount(reflog);

	entry = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx);

	if (entry == NULL) {
	giterr_set(GITERR_REFERENCE, "No reflog entry at index "PRIuZ, idx);
	return GIT_ENOTFOUND;
	}

	reflog_entry_free(entry);

	if (git_vector_remove(
	&reflog->entries, reflog_inverse_index(idx, entrycount)) < 0)
	return -1;

	if (!rewrite_previous_entry)
	return 0;

	/* No need to rewrite anything when removing the most recent entry */
	if (idx == 0)
	return 0;

	/* Have the latest entry just been dropped? */
	if (entrycount == 1)
	return 0;

	entry = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx - 1);

	/* If the oldest entry has just been removed... */
	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;

	return 0;
	}

	previous = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx);
	git_oid_cpy(&entry->oid_old, &previous->oid_cur);

	return 0;
	}