/* Copyright (C) 2003-2004 Timo Sirainen */

#include "lib.h"
#include "ioloop.h"
#include "array.h"
#include "buffer.h"
#include "hash.h"
#include "mmap-util.h"
#include "nfs-workarounds.h"
#include "read-full.h"
#include "write-full.h"
#include "mail-index-private.h"
#include "mail-index-view-private.h"
#include "mail-index-sync-private.h"
#include "mail-transaction-log.h"
#include "mail-cache.h"

#include <stdio.h>
#include <stddef.h>
#include <time.h>
#include <sys/stat.h>

struct mail_index_module_register mail_index_module_register = { 0 };

struct mail_index *mail_index_alloc(const char *dir, const char *prefix)
{
	struct mail_index *index;

	index = i_new(struct mail_index, 1);
	index->dir = i_strdup(dir);
	index->prefix = i_strdup(prefix);
	index->fd = -1;

	index->extension_pool =
		pool_alloconly_create(MEMPOOL_GROWING"index extension", 1024);
	p_array_init(&index->extensions, index->extension_pool, 5);
	i_array_init(&index->sync_lost_handlers, 4);
	i_array_init(&index->module_contexts,
		     I_MIN(5, mail_index_module_register.id));

	index->mode = 0600;
	index->gid = (gid_t)-1;

	index->keywords_ext_id =
		mail_index_ext_register(index, "keywords", 128, 2, 1);
	index->keywords_pool = pool_alloconly_create("keywords", 512);
	i_array_init(&index->keywords, 16);
	index->keywords_hash =
		hash_create(default_pool, index->keywords_pool, 0,
			    strcase_hash, (hash_cmp_callback_t *)strcasecmp);
	index->log = mail_transaction_log_alloc(index);
	return index;
}

void mail_index_free(struct mail_index **_index)
{
	struct mail_index *index = *_index;

	*_index = NULL;
	mail_index_close(index);

	mail_transaction_log_free(&index->log);
	hash_destroy(index->keywords_hash);
	pool_unref(index->extension_pool);
	pool_unref(index->keywords_pool);

	array_free(&index->sync_lost_handlers);
	array_free(&index->keywords);
	array_free(&index->module_contexts);

	i_free(index->error);
	i_free(index->dir);
	i_free(index->prefix);
	i_free(index);
}

void mail_index_set_permissions(struct mail_index *index,
				mode_t mode, gid_t gid)
{
	index->mode = mode & 0666;
	index->gid = gid;
}

uint32_t mail_index_ext_register(struct mail_index *index, const char *name,
				 uint32_t default_hdr_size,
				 uint16_t default_record_size,
				 uint16_t default_record_align)
{
        const struct mail_index_registered_ext *extensions;
	struct mail_index_registered_ext rext;
	unsigned int i, ext_count;

	extensions = array_get(&index->extensions, &ext_count);

	/* see if it's already there */
	for (i = 0; i < ext_count; i++) {
		if (strcmp(extensions[i].name, name) == 0)
			return i;
	}

	memset(&rext, 0, sizeof(rext));
	rext.name = p_strdup(index->extension_pool, name);
	rext.index_idx = ext_count;
	rext.hdr_size = default_hdr_size;
	rext.record_size = default_record_size;
	rext.record_align = default_record_align;

	array_append(&index->extensions, &rext, 1);
	return ext_count;
}

void mail_index_register_expunge_handler(struct mail_index *index,
					 uint32_t ext_id, bool call_always,
					 mail_index_expunge_handler_t *cb,
					 void *context)
{
	struct mail_index_registered_ext *rext;

	rext = array_idx_modifiable(&index->extensions, ext_id);
	i_assert(rext->expunge_handler == NULL || rext->expunge_handler == cb);

	rext->expunge_handler = cb;
	rext->expunge_context = context;
	rext->expunge_handler_call_always = call_always;
}

void mail_index_unregister_expunge_handler(struct mail_index *index,
					   uint32_t ext_id)
{
	struct mail_index_registered_ext *rext;

	rext = array_idx_modifiable(&index->extensions, ext_id);
	i_assert(rext->expunge_handler != NULL);

	rext->expunge_handler = NULL;
}

void mail_index_register_sync_handler(struct mail_index *index, uint32_t ext_id,
				      mail_index_sync_handler_t *cb,
				      enum mail_index_sync_handler_type type)
{
	struct mail_index_registered_ext *rext;

	rext = array_idx_modifiable(&index->extensions, ext_id);
	i_assert(rext->sync_handler.callback == NULL);

	rext->sync_handler.callback = cb;
	rext->sync_handler.type = type;
}

void mail_index_unregister_sync_handler(struct mail_index *index,
					uint32_t ext_id)
{
	struct mail_index_registered_ext *rext;

	rext = array_idx_modifiable(&index->extensions, ext_id);
	i_assert(rext->sync_handler.callback != NULL);

	rext->sync_handler.callback = NULL;
	rext->sync_handler.type = 0;
}

void mail_index_register_sync_lost_handler(struct mail_index *index,
					   mail_index_sync_lost_handler_t *cb)
{
	array_append(&index->sync_lost_handlers, &cb, 1);
}

void mail_index_unregister_sync_lost_handler(struct mail_index *index,
					     mail_index_sync_lost_handler_t *cb)
{
	mail_index_sync_lost_handler_t *const *handlers;
	unsigned int i, count;

	handlers = array_get(&index->sync_lost_handlers, &count);
	for (i = 0; i < count; i++) {
		if (handlers[i] == cb) {
			array_delete(&index->sync_lost_handlers, i, 1);
			break;
		}
	}
}

bool mail_index_keyword_lookup(struct mail_index *index,
			       const char *keyword, bool autocreate,
			       unsigned int *idx_r)
{
	char *keyword_dup;
	void *value;

	/* keywords_hash keeps a name => index mapping of keywords.
	   Keywords are never removed from it, so the index values are valid
	   for the lifetime of the mail_index. */
	if (hash_lookup_full(index->keywords_hash, keyword, NULL, &value)) {
		*idx_r = POINTER_CAST_TO(value, unsigned int);
		return TRUE;
	}

	if (!autocreate) {
		*idx_r = (unsigned int)-1;
		return FALSE;
	}

	keyword = keyword_dup = p_strdup(index->keywords_pool, keyword);
	*idx_r = array_count(&index->keywords);

	hash_insert(index->keywords_hash, keyword_dup, POINTER_CAST(*idx_r));
	array_append(&index->keywords, &keyword, 1);
	return TRUE;
}

int mail_index_map_parse_keywords(struct mail_index_map *map)
{
	struct mail_index *index = map->index;
	const struct mail_index_ext *ext;
	const struct mail_index_keyword_header *kw_hdr;
	const struct mail_index_keyword_header_rec *kw_rec;
	const char *name;
	unsigned int i, name_area_end_offset, old_count;
	uint32_t ext_id;

	map->keywords_read = TRUE;

	ext_id = mail_index_map_lookup_ext(map, "keywords");
	if (ext_id == (uint32_t)-1) {
		if (array_is_created(&map->keyword_idx_map))
			array_clear(&map->keyword_idx_map);
		return 0;
	}

	ext = array_idx(&map->extensions, ext_id);

	/* Extension header contains:
	   - struct mail_index_keyword_header
	   - struct mail_index_keyword_header_rec * keywords_count
	   - const char names[] * keywords_count
	*/
	i_assert(ext->hdr_offset < map->hdr.header_size);
	kw_hdr = CONST_PTR_OFFSET(map->hdr_base, ext->hdr_offset);
	kw_rec = (const void *)(kw_hdr + 1);
	name = (const char *)(kw_rec + kw_hdr->keywords_count);

	old_count = !array_is_created(&map->keyword_idx_map) ? 0 :
		array_count(&map->keyword_idx_map);

	/* Keywords can only be added into same mapping. Removing requires a
	   new mapping (recreating the index file) */
	if (kw_hdr->keywords_count == old_count) {
		/* nothing changed */
		return 0;
	}

	/* make sure the header is valid */
	if (kw_hdr->keywords_count < old_count) {
		mail_index_set_error(index, "Corrupted index file %s: "
				     "Keywords removed unexpectedly",
				     index->filepath);
		return -1;
	}

	if ((size_t)(name - (const char *)kw_hdr) > ext->hdr_size) {
		mail_index_set_error(index, "Corrupted index file %s: "
				     "keywords_count larger than header size",
				     index->filepath);
		return -1;
	}

	name_area_end_offset = (const char *)kw_hdr + ext->hdr_size - name;
	for (i = 0; i < kw_hdr->keywords_count; i++) {
		if (kw_rec[i].name_offset > name_area_end_offset) {
			mail_index_set_error(index, "Corrupted index file %s: "
				"name_offset points outside allocated header",
				index->filepath);
			return -1;
		}
	}
	if (name[name_area_end_offset-1] != '\0') {
		mail_index_set_error(index, "Corrupted index file %s: "
				     "Keyword header doesn't end with NUL",
				     index->filepath);
		return -1;
	}

	/* create file -> index mapping */
	if (!array_is_created(&map->keyword_idx_map)) 
		i_array_init(&map->keyword_idx_map, kw_hdr->keywords_count);

#ifdef DEBUG
	/* Check that existing headers are still the same. It's behind DEBUG
	   since it's pretty useless waste of CPU normally. */
	for (i = 0; i < array_count(&map->keyword_idx_map); i++) {
		const char *keyword = name + kw_rec[i].name_offset;
		const unsigned int *old_idx;
		unsigned int idx;

		old_idx = array_idx(&map->keyword_idx_map, i);
		if (!mail_index_keyword_lookup(index, keyword, FALSE, &idx) ||
		    idx != *old_idx) {
			mail_index_set_error(index, "Corrupted index file %s: "
					     "Keywords changed unexpectedly",
					     index->filepath);
			return -1;
		}
	}
#endif
	/* Register the newly seen keywords */
	i = array_count(&map->keyword_idx_map);
	for (; i < kw_hdr->keywords_count; i++) {
		const char *keyword = name + kw_rec[i].name_offset;
		unsigned int idx;

		(void)mail_index_keyword_lookup(index, keyword, TRUE, &idx);
		array_append(&map->keyword_idx_map, &idx, 1);
	}
	return 0;
}

const ARRAY_TYPE(keywords) *mail_index_get_keywords(struct mail_index *index)
{
	/* Make sure all the keywords are in index->keywords. It's quick to do
	   if nothing has changed. */
	(void)mail_index_map_parse_keywords(index->map);

	return &index->keywords;
}

int mail_index_try_open_only(struct mail_index *index)
{
	i_assert(index->fd == -1);
	i_assert(!MAIL_INDEX_IS_IN_MEMORY(index));

        /* Note that our caller must close index->fd by itself. */
	index->fd = nfs_safe_open(index->filepath, O_RDWR);
	index->readonly = FALSE;

	if (index->fd == -1 && errno == EACCES) {
		index->fd = open(index->filepath, O_RDONLY);
		index->readonly = TRUE;
	}

	if (index->fd == -1) {
		if (errno != ENOENT)
			return mail_index_set_syscall_error(index, "open()");

		/* have to create it */
		return 0;
	}
	return 1;
}

static int
mail_index_try_open(struct mail_index *index)
{
	int ret;

        i_assert(index->fd == -1);

	if (MAIL_INDEX_IS_IN_MEMORY(index))
		return 0;

	i_assert(index->map == NULL || index->map->lock_id == 0);
	ret = mail_index_map(index, MAIL_INDEX_SYNC_HANDLER_HEAD);
	if (ret == 0) {
		/* it's corrupted - recreate it */
		if (index->fd != -1) {
			if (close(index->fd) < 0)
				mail_index_set_syscall_error(index, "close()");
			index->fd = -1;
		}
	}
	return ret;
}

int mail_index_create_tmp_file(struct mail_index *index, const char **path_r)
{
        mode_t old_mask;
	const char *path;
	int fd;

	i_assert(!MAIL_INDEX_IS_IN_MEMORY(index));

	path = *path_r = t_strconcat(index->filepath, ".tmp", NULL);
	old_mask = umask(0);
	fd = open(path, O_RDWR|O_CREAT|O_TRUNC, index->mode);
	umask(old_mask);
	if (fd == -1)
		return mail_index_file_set_syscall_error(index, path, "open()");

	if (index->gid != (gid_t)-1 && fchown(fd, (uid_t)-1, index->gid) < 0) {
		mail_index_file_set_syscall_error(index, path, "fchown()");
		return -1;
	}

	return fd;
}

static bool mail_index_open_files(struct mail_index *index,
				  enum mail_index_open_flags flags)
{
	int ret;
	bool created = FALSE;

	ret = mail_transaction_log_open(index->log);
	if (ret == 0) {
		if ((flags & MAIL_INDEX_OPEN_FLAG_CREATE) == 0)
			return FALSE;

		/* if dovecot.index exists, read it first so that we can get
		   the correct indexid and log sequence */
		(void)mail_index_try_open(index);

		if (index->indexid == 0) {
			/* create a new indexid for us */
			index->indexid = ioloop_time;
		}

		ret = mail_transaction_log_create(index->log);
		created = TRUE;
	}
	if (ret >= 0) {
		ret = index->map != NULL ? 0 : mail_index_try_open(index);
		if (ret == 0) {
			/* doesn't exist / corrupted */
			index->map = mail_index_map_alloc(index);
		}
	}
	if (ret < 0) {
		/* open/create failed, fallback to in-memory indexes */
		if ((flags & MAIL_INDEX_OPEN_FLAG_CREATE) == 0)
			return FALSE;

		if (mail_index_move_to_memory(index) < 0)
			return FALSE;
	}

	index->cache = created ? mail_cache_create(index) :
		mail_cache_open_or_create(index);
	return TRUE;
}

int mail_index_open(struct mail_index *index, enum mail_index_open_flags flags,
		    enum file_lock_method lock_method)
{
	int i = 0, ret = 1;

	if (index->opened) {
		if (index->map != NULL &&
		    (index->map->hdr.flags &
		     MAIL_INDEX_HDR_FLAG_CORRUPTED) != 0) {
			/* corrupted, reopen files */
                        mail_index_close(index);
		} else {
			i_assert(index->map != NULL);
			return 1;
		}
	}

	index->filepath = MAIL_INDEX_IS_IN_MEMORY(index) ?
		i_strdup("(in-memory index)") :
		i_strconcat(index->dir, "/", index->prefix, NULL);

	for (;;) {
		index->shared_lock_count = 0;
		index->excl_lock_count = 0;
		index->lock_type = F_UNLCK;
		index->lock_id_counter = 2;

		index->readonly = FALSE;
		index->nodiskspace = FALSE;
		index->index_lock_timeout = FALSE;
		index->log_locked = FALSE;
		index->mmap_disable =
			(flags & MAIL_INDEX_OPEN_FLAG_MMAP_DISABLE) != 0;
		index->use_excl_dotlocks =
			(flags & MAIL_INDEX_OPEN_FLAG_DOTLOCK_USE_EXCL) != 0;
		index->fsync_disable =
			(flags & MAIL_INDEX_OPEN_FLAG_FSYNC_DISABLE) != 0;
		index->nfs_flush =
			(flags & MAIL_INDEX_OPEN_FLAG_NFS_FLUSH) != 0;
		index->lock_method = lock_method;

		if (index->nfs_flush && index->fsync_disable)
			i_fatal("nfs flush requires fsync_disable=no");
		if (index->nfs_flush && !index->mmap_disable)
			i_fatal("nfs flush requires mmap_disable=yes");

		i_assert(!index->opened);
		if (!mail_index_open_files(index, flags)) {
			/* doesn't exist and create flag not used */
			ret = 0;
			break;
		}
		i_assert(index->map != NULL);

		index->opened = TRUE;
		if (index->fsck) {
			index->fsck = FALSE;
			ret = mail_index_fsck(index);
			if (ret == 0) {
				/* completely broken, reopen */
				if (i++ < 3) {
					mail_index_close(index);
					continue;
				}
				/* too many tries */
				ret = -1;
			}
		}
		break;
	}

	if (ret <= 0)
		mail_index_close(index);

	i_assert(ret <= 0 || index->map != NULL);
	return ret;
}

static void mail_index_close_file(struct mail_index *index)
{
	if (index->file_lock != NULL)
		file_lock_free(&index->file_lock);

	if (index->fd != -1) {
		if (close(index->fd) < 0)
			mail_index_set_syscall_error(index, "close()");
		index->fd = -1;
	}

	if (index->lock_type == F_RDLCK)
		index->lock_type = F_UNLCK;
	index->lock_id_counter += 2;
	index->shared_lock_count = 0;
}

void mail_index_close(struct mail_index *index)
{
	if (index->map != NULL)
		mail_index_unmap(&index->map);

	mail_index_close_file(index);
	mail_transaction_log_close(index->log);
	if (index->cache != NULL)
		mail_cache_free(&index->cache);

	i_free_and_null(index->filepath);

	index->indexid = 0;
	index->opened = FALSE;
}

int mail_index_reopen_if_changed(struct mail_index *index)
{
	struct stat st1, st2;

	i_assert(index->excl_lock_count == 0);

	if (MAIL_INDEX_IS_IN_MEMORY(index))
		return 0;

	if (index->fd == -1)
		return mail_index_try_open_only(index);

	if (fstat(index->fd, &st1) < 0) {
		if (errno != ESTALE)
			return mail_index_set_syscall_error(index, "fstat()");
		/* deleted/recreated, reopen */
		return mail_index_try_open_only(index);
	}

	if (index->nfs_flush)
		nfs_flush_attr_cache(index->filepath);
	if (nfs_safe_stat(index->filepath, &st2) < 0) {
		if (errno == ENOENT)
			return 0;

		return mail_index_set_syscall_error(index, "stat()");
	}

	if (st1.st_ino == st2.st_ino && CMP_DEV_T(st1.st_dev, st2.st_dev)) {
		/* the same file */
		return 1;
	}

	/* new file, new locks. the old fd can keep its locks, they don't
	   matter anymore as no-one's going to modify the file. */
	mail_index_close_file(index);

	return mail_index_try_open_only(index);
}

int mail_index_refresh(struct mail_index *index)
{
	int ret;

	if (MAIL_INDEX_IS_IN_MEMORY(index))
		return 0;

	if (index->excl_lock_count > 0) {
		/* we have index exclusively locked, nothing could
		   have changed. */
		return 0;
	}

	ret = mail_index_map(index, MAIL_INDEX_SYNC_HANDLER_HEAD);
	return ret <= 0 ? -1 : 0;
}

struct mail_cache *mail_index_get_cache(struct mail_index *index)
{
	return index->cache;
}

int mail_index_set_error(struct mail_index *index, const char *fmt, ...)
{
	va_list va;

	i_free(index->error);

	if (fmt == NULL)
		index->error = NULL;
	else {
		va_start(va, fmt);
		index->error = i_strdup_vprintf(fmt, va);
		va_end(va);

		i_error("%s", index->error);
	}

	return -1;
}

int mail_index_move_to_memory(struct mail_index *index)
{
	struct mail_index_map *map;

	if (MAIL_INDEX_IS_IN_MEMORY(index))
		return index->map == NULL ? -1 : 0;

	/* set the index as being into memory */
	i_free_and_null(index->dir);

	i_free(index->filepath);
	index->filepath = i_strdup("(in-memory index)");

	if (index->map == NULL) {
		/* index was never even opened. just mark it as being in
		   memory and let the caller re-open the index. */
		i_assert(index->fd == -1);
		return -1;
	}

	/* move index map to memory */
	if (!MAIL_INDEX_MAP_IS_IN_MEMORY(index->map)) {
		map = mail_index_map_clone(index->map);
		mail_index_unmap(&index->map);
		index->map = map;
	}

	if (index->log != NULL) {
		/* move transaction log to memory */
		mail_transaction_log_move_to_memory(index->log);
	}

	if (index->file_lock != NULL)
		file_lock_free(&index->file_lock);

	if (index->fd != -1) {
		if (close(index->fd) < 0)
			mail_index_set_syscall_error(index, "close()");
		index->fd = -1;
	}
	return 0;
}

void mail_index_mark_corrupted(struct mail_index *index)
{
	index->indexid = 0;

	index->map->hdr.flags |= MAIL_INDEX_HDR_FLAG_CORRUPTED;
	if (unlink(index->filepath) < 0 && errno != ENOENT && errno != ESTALE)
		mail_index_set_syscall_error(index, "unlink()");
}

int mail_index_set_syscall_error(struct mail_index *index,
				 const char *function)
{
	i_assert(function != NULL);

	if (ENOSPACE(errno)) {
		index->nodiskspace = TRUE;
		return -1;
	}

	return mail_index_set_error(index, "%s failed with index file %s: %m",
				    function, index->filepath);
}

int mail_index_file_set_syscall_error(struct mail_index *index,
				      const char *filepath,
				      const char *function)
{
	i_assert(filepath != NULL);
	i_assert(function != NULL);

	if (ENOSPACE(errno)) {
		index->nodiskspace = TRUE;
		return -1;
	}

	return mail_index_set_error(index, "%s failed with file %s: %m",
				    function, filepath);
}

const char *mail_index_get_error_message(struct mail_index *index)
{
	return index->error;
}

void mail_index_reset_error(struct mail_index *index)
{
	if (index->error != NULL) {
		i_free(index->error);
		index->error = NULL;
	}

	index->nodiskspace = FALSE;
        index->index_lock_timeout = FALSE;
}

#ifdef WORDS_BIGENDIAN
/* FIXME: Unfortunately these functions were originally written to use
   endian-specific code and we can't avoid that without breaking backwards
   compatibility. When we do break it, just select one of these. */
uint32_t mail_index_uint32_to_offset(uint32_t offset)
{
	i_assert(offset < 0x40000000);
	i_assert((offset & 3) == 0);

	offset >>= 2;
	return  0x00000080 | ((offset & 0x0000007f)) |
		0x00008000 | ((offset & 0x00003f80) >> 7 << 8) |
		0x00800000 | ((offset & 0x001fc000) >> 14 << 16) |
		0x80000000 | ((offset & 0x0fe00000) >> 21 << 24);
}

uint32_t mail_index_offset_to_uint32(uint32_t offset)
{
	if ((offset & 0x80808080) != 0x80808080)
		return 0;

	return  (((offset & 0x0000007f)) |
		 ((offset & 0x00007f00) >> 8 << 7) |
		 ((offset & 0x007f0000) >> 16 << 14) |
		 ((offset & 0x7f000000) >> 24 << 21)) << 2;
}
#else
uint32_t mail_index_uint32_to_offset(uint32_t offset)
{
	i_assert(offset < 0x40000000);
	i_assert((offset & 3) == 0);

	offset >>= 2;
	return  0x80000000 | ((offset & 0x0000007f) << 24) |
		0x00800000 | ((offset & 0x00003f80) >> 7 << 16) |
		0x00008000 | ((offset & 0x001fc000) >> 14 << 8) |
		0x00000080 | ((offset & 0x0fe00000) >> 21);
}

uint32_t mail_index_offset_to_uint32(uint32_t offset)
{
	if ((offset & 0x80808080) != 0x80808080)
		return 0;

	return  (((offset & 0x0000007f) << 21) |
		 ((offset & 0x00007f00) >> 8 << 14) |
		 ((offset & 0x007f0000) >> 16 << 7) |
		 ((offset & 0x7f000000) >> 24)) << 2;
}
#endif