/* Copyright (c) 2004-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "ioloop.h"
#include "str.h"
#include "mkdir-parents.h"
#include "mailbox-list-private.h"
#include "maildir-storage.h"
#include "maildir-uidlist.h"
#include "maildir-keywords.h"
#include "maildir-filename-flags.h"
#include "maildir-sync.h"

#include <stdio.h>
#include <unistd.h>
#include <dirent.h>
#include <fcntl.h>
#include <utime.h>
#include <sys/stat.h>

#define MAILDIR_RESYNC_RETRY_COUNT 10

static const char *
maildir_filename_guess(struct maildir_mailbox *mbox, uint32_t uid,
		       const char *fname,
		       enum maildir_uidlist_rec_flag *uidlist_flags,
		       bool *have_flags_r)

{
	struct mail_index_view *view = mbox->flags_view;
	struct maildir_keywords_sync_ctx *kw_ctx;
	enum mail_flags flags;
	ARRAY_TYPE(keyword_indexes) keywords;
	const char *p;
	uint32_t seq;

	if (view == NULL || !mail_index_lookup_seq(view, uid, &seq)) {
		*have_flags_r = FALSE;
		return fname;
	}

	t_array_init(&keywords, 32);
	mail_index_lookup_view_flags(view, seq, &flags, &keywords);
	if (array_count(&keywords) == 0) {
		*have_flags_r = (flags & MAIL_FLAGS_NONRECENT) != 0;
		fname = maildir_filename_flags_set(fname, flags);
	} else {
		*have_flags_r = TRUE;
		kw_ctx = maildir_keywords_sync_init_readonly(mbox->keywords,
							     mbox->box.index);
		fname = maildir_filename_flags_kw_set(kw_ctx, fname,
						      flags, &keywords);
		maildir_keywords_sync_deinit(&kw_ctx);
	}

	if (*have_flags_r) {
		/* don't even bother looking into new/ dir */
		*uidlist_flags &= MAILDIR_UIDLIST_REC_FLAG_NEW_DIR;
	} else if ((*uidlist_flags & MAILDIR_UIDLIST_REC_FLAG_MOVED) == 0 &&
		   ((*uidlist_flags & MAILDIR_UIDLIST_REC_FLAG_NEW_DIR) != 0 ||
		    mailbox_recent_flags_have_uid(&mbox->box, uid))) {
		/* probably in new/ dir, drop ":2," from fname */
		*uidlist_flags |= MAILDIR_UIDLIST_REC_FLAG_NEW_DIR;
		p = strrchr(fname, MAILDIR_INFO_SEP);
		if (p != NULL)
			fname = t_strdup_until(fname, p);
	}

	return fname;
}

static int maildir_file_do_try(struct maildir_mailbox *mbox, uint32_t uid,
			       maildir_file_do_func *callback, void *context)
{
	const char *path, *fname;
	enum maildir_uidlist_rec_flag flags;
	bool have_flags;
	int ret;

	ret = maildir_sync_lookup(mbox, uid, &flags, &fname);
	if (ret <= 0)
		return ret == 0 ? -2 : -1;

	if ((flags & MAILDIR_UIDLIST_REC_FLAG_NONSYNCED) != 0) {
		/* let's see if we can guess the filename based on index */
		fname = maildir_filename_guess(mbox, uid, fname,
					       &flags, &have_flags);
	}
	/* make a copy, just in case callback refreshes uidlist and
	   the pointer becomes invalid. */
	fname = t_strdup(fname);

	ret = 0;
	if ((flags & MAILDIR_UIDLIST_REC_FLAG_NEW_DIR) != 0) {
		/* probably in new/ dir */
		path = t_strconcat(mailbox_get_path(&mbox->box),
				   "/new/", fname, NULL);
		ret = callback(mbox, path, context);
	}
	if (ret == 0) {
		path = t_strconcat(mailbox_get_path(&mbox->box), "/cur/",
				   fname, NULL);
		ret = callback(mbox, path, context);
	}
	if (ret > 0 && (flags & MAILDIR_UIDLIST_REC_FLAG_NONSYNCED) != 0) {
		/* file was found. make sure we remember its latest name. */
		maildir_uidlist_update_fname(mbox->uidlist, fname);
	} else if (ret == 0 &&
		   (flags & MAILDIR_UIDLIST_REC_FLAG_NONSYNCED) == 0) {
		/* file wasn't found. mark this message nonsynced, so we can
		   retry the lookup by guessing the flags */
		maildir_uidlist_add_flags(mbox->uidlist, fname,
					  MAILDIR_UIDLIST_REC_FLAG_NONSYNCED);
	}
	return ret;
}

static int do_racecheck(struct maildir_mailbox *mbox, const char *path,
			void *context)
{
	const uint32_t *uidp = context;
	struct stat st;
	int ret;

	ret = lstat(path, &st);
	if (ret == 0 && (st.st_mode & S_IFMT) == S_IFLNK) {
		/* most likely a symlink pointing to a nonexistent file */
		mail_storage_set_critical(&mbox->storage->storage,
			"Maildir: Symlink destination doesn't exist for UID=%u: %s", *uidp, path);
		return -2;
	} else if (ret < 0 && errno != ENOENT) {
		mail_storage_set_critical(&mbox->storage->storage,
			"lstat(%s) failed: %m", path);
		return -1;
	} else {
		/* success or ENOENT, either way we're done */
		mail_storage_set_critical(&mbox->storage->storage,
			"maildir_file_do(%s): Filename keeps changing for UID=%u", path, *uidp);
		return -1;
	}
}

#undef maildir_file_do
int maildir_file_do(struct maildir_mailbox *mbox, uint32_t uid,
		    maildir_file_do_func *callback, void *context)
{
	int i, ret;

	T_BEGIN {
		ret = maildir_file_do_try(mbox, uid, callback, context);
	} T_END;
	if (ret == 0 && mbox->storage->set->maildir_very_dirty_syncs) T_BEGIN {
		/* try guessing again with refreshed flags */
		if (maildir_sync_refresh_flags_view(mbox) == 0)
			ret = maildir_file_do_try(mbox, uid, callback, context);
	} T_END;
	for (i = 0; i < MAILDIR_RESYNC_RETRY_COUNT && ret == 0; i++) {
		/* file is either renamed or deleted. sync the maildir and
		   see which one. if file appears to be renamed constantly,
		   don't try to open it more than 10 times. */
		if (maildir_storage_sync_force(mbox, uid) < 0)
			return -1;

		T_BEGIN {
			ret = maildir_file_do_try(mbox, uid, callback, context);
		} T_END;
	}

	if (i == MAILDIR_RESYNC_RETRY_COUNT) T_BEGIN {
		ret = maildir_file_do_try(mbox, uid, do_racecheck, &uid);
	} T_END;

	return ret == -2 ? 0 : ret;
}

static int maildir_create_path(struct mailbox *box, const char *path,
			       enum mailbox_list_path_type type, bool retry)
{
	const struct mailbox_permissions *perm = mailbox_get_permissions(box);
	const char *p, *parent;

	if (mkdir_chgrp(path, perm->dir_create_mode, perm->file_create_gid,
			perm->file_create_gid_origin) == 0)
		return 0;

	switch (errno) {
	case EEXIST:
		return 0;
	case ENOENT:
		p = strrchr(path, '/');
		if (type == MAILBOX_LIST_PATH_TYPE_MAILBOX ||
		    p == NULL || !retry) {
			/* mailbox was being deleted just now */
			mailbox_set_deleted(box);
			return -1;
		}
		/* create index/control root directory */
		parent = t_strdup_until(path, p);
		if (mailbox_list_mkdir_root(box->list, parent, type) < 0) {
			mail_storage_copy_list_error(box->storage, box->list);
			return -1;
		}
		/* should work now, try again */
		return maildir_create_path(box, path, type, FALSE);
	default:
		mail_storage_set_critical(box->storage,
					  "mkdir(%s) failed: %m", path);
		return -1;
	}
}

static int maildir_create_subdirs(struct mailbox *box)
{
	static const char *subdirs[] = { "cur", "new", "tmp" };
	const char *dirs[N_ELEMENTS(subdirs) + 2];
	enum mailbox_list_path_type types[N_ELEMENTS(subdirs) + 2];
	struct stat st;
	const char *path;
	unsigned int i, count;

	/* @UNSAFE: get a list of directories we want to create */
	for (i = 0; i < N_ELEMENTS(subdirs); i++) {
		types[i] = MAILBOX_LIST_PATH_TYPE_MAILBOX;
		dirs[i] = t_strconcat(mailbox_get_path(box),
				      "/", subdirs[i], NULL);
	}
	if (mailbox_get_path_to(box, MAILBOX_LIST_PATH_TYPE_CONTROL, &path) > 0) {
		types[i] = MAILBOX_LIST_PATH_TYPE_CONTROL;
		dirs[i++] = path;
	}
	if (mailbox_get_path_to(box, MAILBOX_LIST_PATH_TYPE_INDEX, &path) > 0) {
		types[i] = MAILBOX_LIST_PATH_TYPE_INDEX;
		dirs[i++] = path;
	}
	count = i;
	i_assert(count <= N_ELEMENTS(dirs));

	for (i = 0; i < count; i++) {
		path = dirs[i];
		if (stat(path, &st) == 0)
			continue;
		if (errno != ENOENT) {
			mail_storage_set_critical(box->storage,
						  "stat(%s) failed: %m", path);
			break;
		}
		if (maildir_create_path(box, path, types[i], TRUE) < 0)
			break;
	}
	return i == N_ELEMENTS(dirs) ? 0 : -1;
}

bool maildir_set_deleted(struct mailbox *box)
{
	struct stat st;
	int ret;

	if (stat(mailbox_get_path(box), &st) < 0) {
		if (errno == ENOENT)
			mailbox_set_deleted(box);
		else {
			mail_storage_set_critical(box->storage,
				"stat(%s) failed: %m", mailbox_get_path(box));
		}
		return FALSE;
	}
	/* maildir itself exists. create all of its subdirectories in case
	   they got lost. */
	T_BEGIN {
		ret = maildir_create_subdirs(box);
	} T_END;
	return ret < 0 ? FALSE : TRUE;
}

int maildir_lose_unexpected_dir(struct mail_storage *storage, const char *path)
{
	const char *dest, *fname, *p;

	/* There's a directory in maildir, get rid of it.

	   In some installations this was caused by a messed up configuration
	   where e.g. mails was initially delivered to new/new/ directory.
	   Also Dovecot v2.0.0 - v2.0.4 sometimes may have renamed tmp/
	   directory under new/ or cur/. */
	if (rmdir(path) == 0) {
		mail_storage_set_critical(storage,
			"Maildir: rmdir()ed unwanted empty directory: %s",
			path);
		return 1;
	} else if (errno == ENOENT) {
		/* someone else rmdired or renamed it */
		return 0;
	} else if (errno != ENOTEMPTY) {
		mail_storage_set_critical(storage,
			"Maildir: Found unwanted directory %s, "
			"but rmdir() failed: %m", path);
		return -1;
	}

	/* It's not safe to delete this directory since it has some files in it,
	   but it's also not helpful to log this message over and over again.
	   Get rid of this error by renaming the directory elsewhere */
	p = strrchr(path, '/');
	i_assert(p != NULL);
	fname = p + 1;
	while (p != path && p[-1] != '/') p--;
	i_assert(p != NULL);

	dest = t_strconcat(t_strdup_until(path, p), "extra-", fname, NULL);
	if (rename(path, dest) == 0) {
		mail_storage_set_critical(storage,
			"Maildir: renamed unwanted directory %s to %s",
			path, dest);
		return 1;
	} else if (errno == ENOENT) {
		/* someone else renamed it (could have been flag change) */
		return 0;
	} else {
		mail_storage_set_critical(storage,
			"Maildir: Found unwanted directory, "
			"but rename(%s, %s) failed: %m", path, dest);
		return -1;
	}
}