From: Timo Sirainen <tss@iki.fi>
Date: Mon, 14 Jun 2004 19:23:25 +0000 (+0300)
Subject: major syncing code cleanups. the code finally looks almost readable. logic
X-Git-Tag: 1.1.alpha1~3982
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dda2c506c8fc8ac2f88272de4523ded42baa0aa0;p=thirdparty%2Fdovecot%2Fcore.git

major syncing code cleanups. the code finally looks almost readable. logic
should have stayed same.

--HG--
branch : HEAD
---

diff --git a/src/lib-storage/index/mbox/mbox-sync-private.h b/src/lib-storage/index/mbox/mbox-sync-private.h
index 4e3d991f1e..47b45ea49f 100644
--- a/src/lib-storage/index/mbox/mbox-sync-private.h
+++ b/src/lib-storage/index/mbox/mbox-sync-private.h
@@ -60,12 +60,24 @@ struct mbox_sync_mail_context {
 struct mbox_sync_context {
 	struct index_mailbox *ibox;
 	struct istream *input, *file_input;
+	unsigned int lock_id;
 	int fd;
 
+	struct mail_index_sync_ctx *index_sync_ctx;
+	struct mail_index_view *sync_view;
+	struct mail_index_transaction *t;
+	const struct mail_index_header *hdr;
+
 	string_t *header, *from_line;
 	uint32_t base_uid_validity, base_uid_last;
+
+	/* state: */
+	buffer_t *mails, *syncs;
+	struct mail_index_sync_rec sync_rec;
+
 	uint32_t prev_msg_uid, next_uid, first_uid;
-	off_t expunged_space;
+	uint32_t seq, idx_seq, need_space_seq;
+	off_t expunged_space, space_diff;
 };
 
 int mbox_sync(struct index_mailbox *ibox, int last_commit);
@@ -77,7 +89,7 @@ void mbox_sync_update_header(struct mbox_sync_mail_context *ctx,
 void mbox_sync_update_header_from(struct mbox_sync_mail_context *ctx,
 				  const struct mbox_sync_mail *mail);
 int mbox_sync_try_rewrite(struct mbox_sync_mail_context *ctx, off_t move_diff);
-int mbox_sync_rewrite(struct mbox_sync_context *sync_ctx, buffer_t *mails_buf,
+int mbox_sync_rewrite(struct mbox_sync_context *sync_ctx,
 		      uint32_t first_seq, uint32_t last_seq, off_t extra_space);
 
 int mbox_move(struct mbox_sync_context *sync_ctx,
diff --git a/src/lib-storage/index/mbox/mbox-sync-rewrite.c b/src/lib-storage/index/mbox/mbox-sync-rewrite.c
index 8e936b8f4b..c37c101e31 100644
--- a/src/lib-storage/index/mbox/mbox-sync-rewrite.c
+++ b/src/lib-storage/index/mbox/mbox-sync-rewrite.c
@@ -37,6 +37,12 @@ int mbox_move(struct mbox_sync_context *sync_ctx,
 		ret = ret == (off_t)size ? 0 : -1;
 	}
 
+	if (ret < 0) {
+		errno = output->stream_errno;
+		mbox_set_syscall_error(sync_ctx->ibox,
+				       "o_stream_send_istream()");
+	}
+
 	o_stream_unref(output);
 	return (int)ret;
 }
@@ -189,7 +195,7 @@ int mbox_sync_try_rewrite(struct mbox_sync_mail_context *ctx, off_t move_diff)
 			new_hdr_size - ctx->header_first_change,
 			ctx->hdr_offset + move_diff +
 			ctx->header_first_change) < 0) {
-		// FIXME: error handling
+		mbox_set_syscall_error(ctx->sync_ctx->ibox, "pwrite_full()");
 		return -1;
 	}
 	istream_raw_mbox_flush(ctx->sync_ctx->input);
@@ -249,17 +255,15 @@ static int mbox_sync_read_and_move(struct mbox_sync_context *sync_ctx,
 	   headers. */
 	offset = sync_ctx->file_input->v_offset;
 	if (mbox_move(sync_ctx, offset + mails[idx+1].space, offset,
-		      *end_offset - offset - mails[idx+1].space) < 0) {
-		// FIXME: error handling
+		      *end_offset - offset - mails[idx+1].space) < 0)
 		return -1;
-	}
 	mails[idx+1].from_offset += mails[idx+1].space;
 
 	*end_offset = offset + mails[idx+1].space - str_len(mail_ctx.header);
 
 	if (pwrite_full(sync_ctx->fd, str_data(mail_ctx.header),
 			str_len(mail_ctx.header), *end_offset) < 0) {
-		// FIXME: error handling
+		mbox_set_syscall_error(sync_ctx->ibox, "pwrite_full()");
 		return -1;
 	}
 
@@ -300,7 +304,7 @@ static int mbox_sync_fill_leftover(struct mbox_sync_context *sync_ctx,
 
 	if (pwrite_full(sync_ctx->fd, str_data(mail_ctx.header),
 			str_len(mail_ctx.header), start_offset) < 0) {
-		// FIXME: error handling
+		mbox_set_syscall_error(sync_ctx->ibox, "pwrite_full()");
 		return -1;
 	}
 
@@ -308,7 +312,7 @@ static int mbox_sync_fill_leftover(struct mbox_sync_context *sync_ctx,
 	return 0;
 }
 
-int mbox_sync_rewrite(struct mbox_sync_context *sync_ctx, buffer_t *mails_buf,
+int mbox_sync_rewrite(struct mbox_sync_context *sync_ctx,
 		      uint32_t first_seq, uint32_t last_seq, off_t extra_space)
 {
 	struct mbox_sync_mail *mails;
@@ -320,7 +324,7 @@ int mbox_sync_rewrite(struct mbox_sync_context *sync_ctx, buffer_t *mails_buf,
 	i_assert(first_seq != last_seq);
 	i_assert(sync_ctx->ibox->mbox_lock_type == F_WRLCK);
 
-	mails = buffer_get_modifyable_data(mails_buf, &size);
+	mails = buffer_get_modifyable_data(sync_ctx->mails, &size);
 	i_assert(size / sizeof(*mails) == last_seq - first_seq + 1);
 
 	/* if there's expunges in mails[], we would get more correct balancing
@@ -368,7 +372,6 @@ int mbox_sync_rewrite(struct mbox_sync_context *sync_ctx, buffer_t *mails_buf,
 			dest_offset = offset + mails[idx+1].space;
 			if (mbox_move(sync_ctx, dest_offset, offset,
 				      end_offset - dest_offset) < 0) {
-				// FIXME: error handling
 				ret = -1;
 				break;
 			}
@@ -390,10 +393,8 @@ int mbox_sync_rewrite(struct mbox_sync_context *sync_ctx, buffer_t *mails_buf,
 			   we need to move From-line to start_offset */
 			offset = mails[1].offset;
 			if (mbox_move(sync_ctx, start_offset, end_offset,
-				      offset - end_offset) < 0) {
-				// FIXME: error handling
+				      offset - end_offset) < 0)
 				ret = -1;
-			}
 			mails[1].from_offset -= end_offset - start_offset;
 			idx++;
 
diff --git a/src/lib-storage/index/mbox/mbox-sync-update.c b/src/lib-storage/index/mbox/mbox-sync-update.c
index 5faba2c984..72b5efa18c 100644
--- a/src/lib-storage/index/mbox/mbox-sync-update.c
+++ b/src/lib-storage/index/mbox/mbox-sync-update.c
@@ -1,4 +1,5 @@
 #include "lib.h"
+#include "ioloop.h"
 #include "buffer.h"
 #include "str.h"
 #include "message-parser.h"
@@ -89,6 +90,13 @@ static void mbox_sync_add_missing_headers(struct mbox_sync_mail_context *ctx)
 
 	if (ctx->mail.uid == ctx->sync_ctx->first_uid &&
 	    ctx->hdr_pos[MBOX_HDR_X_IMAPBASE] == (size_t)-1) {
+		if (ctx->sync_ctx->base_uid_validity == 0) {
+			ctx->sync_ctx->base_uid_validity =
+				ctx->sync_ctx->hdr->uid_validity == 0 ?
+				(uint32_t)ioloop_time :
+				ctx->sync_ctx->hdr->uid_validity;
+		}
+
 		ctx->hdr_pos[MBOX_HDR_X_IMAPBASE] = str_len(ctx->header);
 		str_printfa(ctx->header, "X-IMAPbase: %u %010u",
 			    ctx->sync_ctx->base_uid_validity,
@@ -197,6 +205,9 @@ void mbox_sync_update_header(struct mbox_sync_mail_context *ctx,
 		memcpy(old_keywords, ctx->mail.keywords, sizeof(old_keywords));
 
 		for (i = 0; i < size; i++) {
+			if (sync[i].type != MAIL_INDEX_SYNC_TYPE_FLAGS)
+				continue;
+
 			mail_index_sync_flags_apply(&sync[i], &ctx->mail.flags,
 						    ctx->mail.keywords);
 		}
diff --git a/src/lib-storage/index/mbox/mbox-sync.c b/src/lib-storage/index/mbox/mbox-sync.c
index cda172fb0b..e3115de0ea 100644
--- a/src/lib-storage/index/mbox/mbox-sync.c
+++ b/src/lib-storage/index/mbox/mbox-sync.c
@@ -70,8 +70,10 @@ static int mbox_sync_grow_file(struct mbox_sync_context *sync_ctx,
 
 	/* put the extra space between last message's header and body */
 	file_size = i_stream_get_size(sync_ctx->file_input) + grow_size;
-	if (file_set_size(sync_ctx->fd, file_size) < 0)
+	if (file_set_size(sync_ctx->fd, file_size) < 0) {
+		mbox_set_syscall_error(sync_ctx->ibox, "file_set_size()");
 		return -1;
+	}
 
 	src_offset = mail_ctx->body_offset;
 	mail_ctx->body_offset += grow_size;
@@ -102,13 +104,18 @@ static void mbox_sync_buffer_delete_old(buffer_t *syncs_buf, uint32_t uid)
 	buffer_set_used_size(syncs_buf, dest * sizeof(*sync));
 }
 
-static void
-mbox_sync_next_mail(struct mbox_sync_context *sync_ctx,
-		    struct mbox_sync_mail_context *mail_ctx, uint32_t seq)
+static int
+mbox_sync_read_next_mail(struct mbox_sync_context *sync_ctx,
+			 struct mbox_sync_mail_context *mail_ctx)
 {
+	/* set input->eof */
+	(void)istream_raw_mbox_get_header_offset(sync_ctx->input);
+	if (sync_ctx->input->eof)
+		return 0;
+
 	memset(mail_ctx, 0, sizeof(*mail_ctx));
 	mail_ctx->sync_ctx = sync_ctx;
-	mail_ctx->seq = seq;
+	mail_ctx->seq = ++sync_ctx->seq;
 	mail_ctx->header = sync_ctx->header;
 
 	mail_ctx->from_offset =
@@ -116,7 +123,7 @@ mbox_sync_next_mail(struct mbox_sync_context *sync_ctx,
 	mail_ctx->mail.offset =
 		istream_raw_mbox_get_header_offset(sync_ctx->input);
 
-	if (seq > 1 && sync_ctx->first_uid == mail_ctx->mail.uid) {
+	if (mail_ctx->seq > 1 && sync_ctx->first_uid == mail_ctx->mail.uid) {
 		/* First message was expunged and this is the next one.
 		   Skip \n header */
 		mail_ctx->from_offset++;
@@ -136,6 +143,42 @@ mbox_sync_next_mail(struct mbox_sync_context *sync_ctx,
 		mail_ctx->need_rewrite = TRUE;
 		// FIXME: save it somewhere
 	}
+	return 1;
+}
+
+static int mbox_sync_read_index_syncs(struct mbox_sync_context *sync_ctx,
+				      uint32_t uid, int *sync_expunge_r)
+{
+	struct mail_index_sync_rec *sync_rec = &sync_ctx->sync_rec;
+	int ret;
+
+	*sync_expunge_r = FALSE;
+
+	if (sync_ctx->ibox->readonly)
+		return 0;
+
+	mbox_sync_buffer_delete_old(sync_ctx->syncs, uid);
+	while (uid >= sync_rec->uid1) {
+		if (sync_rec->uid1 != 0) {
+			i_assert(uid <= sync_rec->uid2);
+			buffer_append(sync_ctx->syncs, sync_rec,
+				      sizeof(*sync_rec));
+
+			if (sync_rec->type == MAIL_INDEX_SYNC_TYPE_EXPUNGE)
+				*sync_expunge_r = TRUE;
+		}
+
+		ret = mail_index_sync_next(sync_ctx->index_sync_ctx, sync_rec);
+		if (ret < 0)
+			return -1;
+
+		if (ret == 0) {
+			memset(sync_rec, 0, sizeof(*sync_rec));
+			break;
+		}
+	}
+
+	return 0;
 }
 
 static void mbox_sync_apply_index_syncs(buffer_t *syncs_buf, uint8_t *flags,
@@ -151,6 +194,115 @@ static void mbox_sync_apply_index_syncs(buffer_t *syncs_buf, uint8_t *flags,
 		mail_index_sync_flags_apply(&sync[i], flags, keywords);
 }
 
+static int
+mbox_sync_read_index_rec(struct mbox_sync_context *sync_ctx,
+			 uint32_t uid, const struct mail_index_record **rec_r)
+{
+        const struct mail_index_record *rec = NULL;
+	uint32_t messages_count;
+
+	messages_count = mail_index_view_get_message_count(sync_ctx->sync_view);
+	while (sync_ctx->idx_seq < messages_count) {
+		if (mail_index_lookup(sync_ctx->sync_view,
+				      ++sync_ctx->idx_seq, &rec) < 0) {
+			mail_storage_set_index_error(sync_ctx->ibox);
+			return -1;
+		}
+
+		if (uid <= rec->uid)
+			break;
+
+		/* externally expunged message, remove from index */
+		mail_index_expunge(sync_ctx->t, sync_ctx->idx_seq);
+		rec = NULL;
+	}
+
+	if (rec != NULL && rec->uid != uid) {
+		/* new UID in the middle of the mailbox - shouldn't happen */
+		mail_storage_set_critical(sync_ctx->ibox->box.storage,
+			"mbox sync: UID inserted in the middle of mailbox "
+			"(%u > %u)", rec->uid, uid);
+		mail_index_mark_corrupted(sync_ctx->ibox->index);
+		return -1;
+	}
+
+	*rec_r = rec;
+	return 0;
+}
+
+static int
+mbox_sync_update_from_offset(struct mbox_sync_context *sync_ctx,
+                             struct mbox_sync_mail *mail,
+			     int nocheck)
+{
+	const void *data;
+	uint64_t offset;
+
+	if (!nocheck) {
+		/* see if from_offset needs updating */
+		if (mail_index_lookup_extra(sync_ctx->sync_view,
+					    sync_ctx->idx_seq,
+					    sync_ctx->ibox->mbox_extra_idx,
+					    &data) < 0) {
+			mail_storage_set_index_error(sync_ctx->ibox);
+			return -1;
+		}
+
+		offset = *((const uint64_t *)data);
+		if (offset == mail->from_offset)
+			return 0;
+	} else {
+		offset = mail->from_offset;
+	}
+
+	mail_index_update_extra_rec(sync_ctx->t, sync_ctx->idx_seq,
+				    sync_ctx->ibox->mbox_extra_idx, &offset);
+	return 0;
+}
+
+static int mbox_sync_update_index(struct mbox_sync_context *sync_ctx,
+				  struct mbox_sync_mail *mail,
+				  const struct mail_index_record *rec)
+{
+	keywords_mask_t idx_keywords;
+	uint8_t idx_flags, mbox_flags;
+
+	if (rec == NULL) {
+		/* new message */
+		mail_index_append(sync_ctx->t, mail->uid, &sync_ctx->idx_seq);
+		mbox_flags = mail->flags & (MAIL_FLAGS_MASK^MAIL_RECENT);
+		mail_index_update_flags(sync_ctx->t, sync_ctx->idx_seq,
+					MODIFY_REPLACE, mbox_flags,
+					mail->keywords);
+	} else {
+		/* see if flags changed */
+		idx_flags = rec->flags;
+		memcpy(idx_keywords, rec->keywords, INDEX_KEYWORDS_BYTE_COUNT);
+		mbox_sync_apply_index_syncs(sync_ctx->syncs,
+					    &idx_flags, idx_keywords);
+
+		mbox_flags = (rec->flags & ~MAIL_FLAGS_MASK) |
+			(mail->flags & (MAIL_FLAGS_MASK^MAIL_RECENT));
+
+		if (idx_flags != mbox_flags ||
+		    memcmp(idx_keywords, mail->keywords,
+			   INDEX_KEYWORDS_BYTE_COUNT) != 0) {
+			mail_index_update_flags(sync_ctx->t, sync_ctx->idx_seq,
+						MODIFY_REPLACE, mbox_flags,
+						mail->keywords);
+		}
+	}
+
+	/* update from_offsets, but not if we're going to rewrite this message.
+	   rewriting would just move it anyway. */
+	if (sync_ctx->need_space_seq == 0) {
+		int nocheck = rec == NULL || sync_ctx->expunged_space > 0;
+		if (mbox_sync_update_from_offset(sync_ctx, mail, nocheck) < 0)
+			return -1;
+	}
+	return 0;
+}
+
 static int mbox_read_from_line(struct mbox_sync_mail_context *ctx)
 {
 	struct istream *input = ctx->sync_ctx->file_input;
@@ -185,12 +337,9 @@ mbox_write_from_line(struct mbox_sync_mail_context *ctx, off_t move_diff)
 {
 	string_t *str = ctx->sync_ctx->from_line;
 
-	if (move_diff == 0)
-		return 0;
-
 	if (pwrite_full(ctx->sync_ctx->fd, str_data(str), str_len(str),
 			ctx->from_offset + move_diff) < 0) {
-		// FIXME: error handling
+		mbox_set_syscall_error(ctx->sync_ctx->ibox, "pwrite_full()");
 		return -1;
 	}
 
@@ -218,451 +367,381 @@ update_from_offsets(struct index_mailbox *ibox,
 	}
 }
 
-static int mbox_sync_do(struct index_mailbox *ibox,
-			struct mail_index_sync_ctx *index_sync_ctx,
-			struct mail_index_view *sync_view,
-			buffer_t *syncs, struct mail_index_sync_rec *sync_rec,
-			int index_synced)
+static int mbox_sync_handle_expunge(struct mbox_sync_mail_context *mail_ctx)
 {
-	/* a horrible function. needs some serious cleanups. */
-	struct mbox_sync_context sync_ctx;
-	struct mbox_sync_mail_context mail_ctx;
-	struct mail_index_transaction *t;
-	const struct mail_index_header *hdr;
-	const struct mail_index_record *rec;
-	struct istream *input;
-	uint32_t seq, need_space_seq, idx_seq, messages_count;
-	uint8_t new_flags;
-	off_t space_diff, move_diff;
-	uoff_t offset, extra_space, trailer_size;
-	buffer_t *mails;
-	struct stat st;
-	int sync_expunge, update_from_offset, ret = 0;
+	if (mail_ctx->sync_ctx->ibox->mbox_lock_type == F_RDLCK)
+		return -2;
+
+	mail_ctx->mail.offset = mail_ctx->from_offset;
+	mail_ctx->mail.space =
+		mail_ctx->body_offset - mail_ctx->from_offset +
+		mail_ctx->mail.body_size;
+	mail_ctx->mail.body_size = 0;
+
+	if (mail_ctx->sync_ctx->seq == 1) {
+		/* expunging first message, fix space to contain next
+		   message's \n header too since it will be removed. */
+		mail_ctx->mail.space++;
+	}
 
-	if (mail_index_get_header(sync_view, &hdr) < 0)
-		return -1;
+	mail_ctx->sync_ctx->expunged_space += mail_ctx->mail.space;
+	return 0;
+}
 
-	t = mail_index_transaction_begin(sync_view, FALSE);
+static int mbox_sync_handle_header(struct mbox_sync_mail_context *mail_ctx)
+{
+	struct mbox_sync_context *sync_ctx = mail_ctx->sync_ctx;
+	off_t move_diff;
+	int ret;
 
-	memset(&sync_ctx, 0, sizeof(sync_ctx));
-	sync_ctx.ibox = ibox;
-	sync_ctx.file_input = ibox->mbox_file_stream;
-	sync_ctx.input = ibox->mbox_stream;
-	sync_ctx.fd = ibox->mbox_fd;
-	sync_ctx.from_line = str_new(default_pool, 256);
-	sync_ctx.header = str_new(default_pool, 4096);
-	sync_ctx.next_uid = 1;
+	if (sync_ctx->first_uid == 0)
+		sync_ctx->first_uid = mail_ctx->mail.uid;
 
-	input = sync_ctx.input;
-	istream_raw_mbox_seek(input, 0);
+	if (sync_ctx->ibox->readonly)
+		return 0;
 
-	mails = buffer_create_dynamic(default_pool, 4096, (size_t)-1);
+	if (sync_ctx->expunged_space > 0 && sync_ctx->need_space_seq == 0) {
+		/* move the header backwards to fill expunged space */
+		if (sync_ctx->ibox->mbox_lock_type == F_RDLCK)
+			return -2;
 
-	messages_count = mail_index_view_get_message_count(sync_view);
+		move_diff = -sync_ctx->expunged_space;
 
-	space_diff = 0; need_space_seq = 0; idx_seq = 0; rec = NULL;
-	for (seq = 0;;) {
-		/* set input->eof */
-		(void)istream_raw_mbox_get_header_offset(input);
-		if (input->eof)
-			break;
-		seq++;
+		/* read the From-line before rewriting overwrites it */
+		if (mbox_read_from_line(mail_ctx) < 0)
+			return -1;
 
-		mbox_sync_next_mail(&sync_ctx, &mail_ctx, seq);
+		mbox_sync_update_header(mail_ctx, sync_ctx->syncs);
+		if ((ret = mbox_sync_try_rewrite(mail_ctx, move_diff)) < 0)
+			return -1;
 
-		/* get all sync records related to this message */
-		ret = 1; sync_expunge = FALSE;
-		mbox_sync_buffer_delete_old(syncs, mail_ctx.mail.uid);
-		while (mail_ctx.mail.uid >= sync_rec->uid1 && ret > 0) {
-			if (sync_rec->uid1 != 0) {
-				i_assert(mail_ctx.mail.uid <= sync_rec->uid2);
-				buffer_append(syncs, sync_rec,
-					      sizeof(*sync_rec));
-
-				if (sync_rec->type ==
-				    MAIL_INDEX_SYNC_TYPE_EXPUNGE)
-					sync_expunge = TRUE;
-			}
-			ret = mail_index_sync_next(index_sync_ctx, sync_rec);
-			if (ret == 0)
-				memset(sync_rec, 0, sizeof(*sync_rec));
+		if (ret > 0) {
+			/* rewrite successful, write From-line to
+			   new location */
+			mail_ctx->mail.from_offset += move_diff;
+			mail_ctx->mail.offset += move_diff;
+			if (mbox_write_from_line(mail_ctx, move_diff) < 0)
+				return -1;
 		}
-		if (ret < 0)
-			break;
+	} else if (mail_ctx->need_rewrite ||
+		   buffer_get_used_size(sync_ctx->syncs) != 0) {
+		if (sync_ctx->ibox->mbox_lock_type == F_RDLCK)
+			return -2;
 
-		if (seq == 1 && sync_ctx.base_uid_validity == 0) {
-			sync_ctx.base_uid_validity =
-				hdr->uid_validity == 0 ? (uint32_t)ioloop_time :
-				hdr->uid_validity;
-		}
+		mbox_sync_update_header(mail_ctx, sync_ctx->syncs);
+		if ((ret = mbox_sync_try_rewrite(mail_ctx, move_diff)) < 0)
+			return -1;
+	} else {
+		/* nothing to do */
+		return 0;
+	}
 
-		if (!sync_expunge && sync_ctx.first_uid == 0)
-			sync_ctx.first_uid = mail_ctx.mail.uid;
-
-		if ((mail_ctx.need_rewrite || sync_ctx.expunged_space > 0 ||
-		     buffer_get_used_size(syncs) != 0) && !ibox->readonly) {
-			if (ibox->mbox_lock_type == F_RDLCK) {
-				ret = -2;
-				break;
-			}
-
-			if (sync_expunge) {
-				ret = 1;
-				mail_ctx.mail.offset = mail_ctx.from_offset;
-				mail_ctx.mail.space =
-					mail_ctx.body_offset -
-					mail_ctx.from_offset +
-					mail_ctx.mail.body_size;
-				mail_ctx.mail.body_size = 0;
-
-				if (seq == 1)
-					mail_ctx.mail.space++;
-
-				sync_ctx.expunged_space += mail_ctx.mail.space;
-			} else {
-				move_diff = need_space_seq != 0 ? 0 :
-					-sync_ctx.expunged_space;
-
-				/* read the From-line */
-				if (move_diff != 0 &&
-				    mbox_read_from_line(&mail_ctx) < 0) {
-					ret = -1;
-					break;
-				}
-
-				mbox_sync_update_header(&mail_ctx, syncs);
-				ret = mbox_sync_try_rewrite(&mail_ctx,
-							    move_diff);
-
-				if (ret > 0) {
-					mail_ctx.mail.from_offset += move_diff;
-					mail_ctx.mail.offset += move_diff;
-					ret = mbox_write_from_line(&mail_ctx,
-								   move_diff);
-					if (ret == 0)
-						ret = 1;
-				}
-
-				if (ret < 0)
-					break;
-			}
-
-			if (ret == 0 && need_space_seq == 0) {
-				/* first mail with no space to write it */
-				need_space_seq = seq;
-				space_diff = 0;
-
-				if (sync_ctx.expunged_space > 0) {
-					/* create dummy message to describe
-					   the expunged data */
-					struct mbox_sync_mail mail;
-
-					memset(&mail, 0, sizeof(mail));
-					mail.offset = mail_ctx.from_offset -
-						sync_ctx.expunged_space;
-					mail.space = sync_ctx.expunged_space;
-
-					need_space_seq--;
-					buffer_append(mails, &mail,
-						      sizeof(mail));
-				}
-			}
+	if (ret == 0 && sync_ctx->need_space_seq == 0) {
+		/* first mail with no space to write it */
+		sync_ctx->need_space_seq = sync_ctx->seq;
+		sync_ctx->space_diff = 0;
+
+		if (sync_ctx->expunged_space > 0) {
+			/* create dummy message to describe the expunged data */
+			struct mbox_sync_mail mail;
+
+			memset(&mail, 0, sizeof(mail));
+			mail.offset = mail_ctx->from_offset -
+				sync_ctx->expunged_space;
+			mail.space = sync_ctx->expunged_space;
+
+			sync_ctx->need_space_seq--;
+			buffer_append(sync_ctx->mails, &mail, sizeof(mail));
 		}
+	}
+	return 0;
+}
+
+static int
+mbox_sync_handle_missing_space(struct mbox_sync_mail_context *mail_ctx)
+{
+	struct mbox_sync_context *sync_ctx = mail_ctx->sync_ctx;
+	uoff_t extra_space;
 
-		/* update index */
-		do {
-			if (rec != NULL && rec->uid >= mail_ctx.mail.uid)
-				break;
+	buffer_append(sync_ctx->mails, &mail_ctx->mail, sizeof(mail_ctx->mail));
 
-			if (idx_seq >= messages_count) {
-				rec = NULL;
-				break;
-			}
+	sync_ctx->space_diff += mail_ctx->mail.space;
+	if (sync_ctx->space_diff < 0)
+		return 0;
 
-			if (rec != NULL)
-				mail_index_expunge(t, idx_seq);
+	/* we have enough space now */
+	extra_space = MBOX_HEADER_EXTRA_SPACE *
+		(sync_ctx->seq - sync_ctx->need_space_seq + 1);
 
-			ret = mail_index_lookup(sync_view, ++idx_seq, &rec);
-		} while (ret == 0);
+	if (mail_ctx->mail.uid == 0 &&
+	    (uoff_t)sync_ctx->space_diff > extra_space) {
+		/* don't waste too much on extra spacing */
+		sync_ctx->expunged_space = sync_ctx->space_diff - extra_space;
+		sync_ctx->space_diff = extra_space;
+	} else {
+		sync_ctx->expunged_space = 0;
+	}
 
-		if (ret < 0)
-			break;
-		if (rec != NULL && rec->uid != mail_ctx.mail.uid) {
-			/* new UID in the middle of the mailbox -
-			   shouldn't happen */
-			mail_storage_set_critical(ibox->box.storage,
-				"mbox sync: UID inserted in the middle "
-				"of mailbox (%u > %u)",
-				rec->uid, mail_ctx.mail.uid);
-			mail_index_mark_corrupted(ibox->index);
-			ret = -1;
-			break;
-		}
+	if (mbox_sync_rewrite(sync_ctx, sync_ctx->need_space_seq, sync_ctx->seq,
+			      sync_ctx->space_diff) < 0)
+		return -1;
 
-		if (sync_expunge) {
-			if (rec != NULL)
-				mail_index_expunge(t, idx_seq);
-			update_from_offset = FALSE;
-		} else if (rec != NULL) {
-			/* see if flags changed */
-			keywords_mask_t old_keywords;
-			uint8_t old_flags;
-
-			old_flags = rec->flags;
-			memcpy(old_keywords, rec->keywords,
-			       INDEX_KEYWORDS_BYTE_COUNT);
-			mbox_sync_apply_index_syncs(syncs, &old_flags,
-						    old_keywords);
-
-			new_flags = (rec->flags & ~MAIL_FLAGS_MASK) |
-				(mail_ctx.mail.flags &
-				 (MAIL_FLAGS_MASK^MAIL_RECENT));
-
-			if (old_flags != new_flags ||
-			    memcmp(old_keywords, mail_ctx.mail.keywords,
-				   INDEX_KEYWORDS_BYTE_COUNT) != 0) {
-				mail_index_update_flags(t, idx_seq,
-							MODIFY_REPLACE,
-							new_flags,
-							mail_ctx.mail.keywords);
-			}
-
-			update_from_offset = sync_ctx.expunged_space > 0;
-
-			/* we used this record */
-			rec = NULL;
-		} else {
-			/* new message */
-			mail_index_append(t, mail_ctx.mail.uid, &idx_seq);
-			new_flags = mail_ctx.mail.flags &
-				(MAIL_FLAGS_MASK^MAIL_RECENT);
-			mail_index_update_flags(t, idx_seq, MODIFY_REPLACE,
-						new_flags,
-						mail_ctx.mail.keywords);
-			update_from_offset = TRUE;
-		}
+	update_from_offsets(sync_ctx->ibox, sync_ctx->t, sync_ctx->mails,
+			    sync_ctx->need_space_seq, sync_ctx->seq);
+
+	/* mail_ctx may contain wrong data after rewrite, so make sure we
+	   don't try to access it */
+	memset(mail_ctx, 0, sizeof(*mail_ctx));
 
-		if (update_from_offset) {
-			/* from_offset needs updating */
-			uint64_t offset;
-
-			offset = mail_ctx.mail.from_offset;
-			mail_index_update_extra_rec(t, idx_seq,
-				ibox->mbox_extra_idx, &offset);
-		} else if (need_space_seq == 0 && !sync_expunge) {
-			/* see if from_offset needs updating */
-			const void *data;
-			uint64_t offset;
-
-			if (mail_index_lookup_extra(sync_view, idx_seq,
-						    ibox->mbox_extra_idx,
-						    &data) < 0) {
-				ret = -1;
-				break;
-			}
-
-			offset = *((const uint64_t *)data);
-			if (offset != mail_ctx.mail.from_offset) {
-				offset = mail_ctx.mail.from_offset;
-				mail_index_update_extra_rec(t, idx_seq,
-					ibox->mbox_extra_idx, &offset);
-			}
+	sync_ctx->need_space_seq = 0;
+	buffer_set_used_size(sync_ctx->mails, 0);
+	return 0;
+}
+
+static int mbox_sync_parse_all(struct mbox_sync_context *sync_ctx,
+			       struct mbox_sync_mail_context *mail_ctx)
+{
+	const struct mail_index_record *rec;
+	uint32_t uid, messages_count;
+	uoff_t offset;
+	int ret, expunged;
+
+	sync_ctx->file_input = sync_ctx->ibox->mbox_file_stream;
+	sync_ctx->input = sync_ctx->ibox->mbox_stream;
+	sync_ctx->fd = sync_ctx->ibox->mbox_fd;
+
+	istream_raw_mbox_seek(sync_ctx->input, 0);
+
+	while ((ret = mbox_sync_read_next_mail(sync_ctx, mail_ctx)) > 0) {
+		uid = mail_ctx->mail.uid;
+
+		/* get all sync records related to this message */
+		if (mbox_sync_read_index_syncs(sync_ctx, uid, &expunged) < 0)
+			return -1;
+
+		if (!expunged)
+			ret = mbox_sync_handle_header(mail_ctx);
+		else {
+			mail_ctx->mail.uid = 0;
+			ret = mbox_sync_handle_expunge(mail_ctx);
+		}
+		if (ret < 0) {
+			/* -1 = error, -2 = need exclusive lock */
+			return ret;
 		}
 
-		istream_raw_mbox_next(input, mail_ctx.mail.body_size);
-		offset = istream_raw_mbox_get_start_offset(input);
+		if (mbox_sync_read_index_rec(sync_ctx, uid, &rec) < 0)
+			return -1;
 
-		if (sync_ctx.expunged_space > 0 && !sync_expunge &&
-		    need_space_seq == 0) {
-			/* move the body */
-			if (mbox_move(&sync_ctx,
-				      mail_ctx.body_offset -
-				      sync_ctx.expunged_space,
-				      mail_ctx.body_offset,
-				      mail_ctx.mail.body_size) < 0) {
-				ret = -1;
-				break;
-			}
-			i_stream_seek(input, offset);
+		if (!expunged) {
+			if (mbox_sync_update_index(sync_ctx, &mail_ctx->mail,
+						   rec) < 0)
+				return -1;
 		}
 
-		if (need_space_seq != 0) {
-			if (sync_expunge)
-				mail_ctx.mail.uid = 0;
-
-			buffer_append(mails, &mail_ctx.mail,
-				      sizeof(mail_ctx.mail));
-
-			space_diff += mail_ctx.mail.space;
-			if (space_diff >= 0) {
-				/* we have enough space now */
-				extra_space = MBOX_HEADER_EXTRA_SPACE *
-					(seq - need_space_seq + 1);
-				if (sync_expunge &&
-				    (size_t)space_diff > extra_space) {
-					/* don't waste too much on extra
-					   spacing */
-					sync_ctx.expunged_space =
-						space_diff - extra_space;
-					space_diff = extra_space;
-				} else {
-					sync_ctx.expunged_space = 0;
-				}
-				if (mbox_sync_rewrite(&sync_ctx, mails,
-						      need_space_seq, seq,
-						      space_diff) < 0) {
-					ret = -1;
-					break;
-				}
-
-				update_from_offsets(ibox, t, mails,
-						    need_space_seq, seq);
-
-				/* mail_ctx may contain wrong data after
-				   rewrite, so make sure we don't try to access
-				   it */
-				memset(&mail_ctx, 0, sizeof(mail_ctx));
-				i_stream_seek(input, offset);
-
-				need_space_seq = 0;
-				buffer_set_used_size(mails, 0);
-			}
+		istream_raw_mbox_next(sync_ctx->input,
+				      mail_ctx->mail.body_size);
+		offset = istream_raw_mbox_get_start_offset(sync_ctx->input);
+
+		if (sync_ctx->need_space_seq != 0) {
+			if (mbox_sync_handle_missing_space(mail_ctx) < 0)
+				return -1;
+			i_stream_seek(sync_ctx->input, offset);
+		} else if (sync_ctx->expunged_space > 0 && !expunged) {
+			/* move the body */
+			if (mbox_move(sync_ctx,
+				      mail_ctx->body_offset -
+				      sync_ctx->expunged_space,
+				      mail_ctx->body_offset,
+				      mail_ctx->mail.body_size) < 0)
+				return -1;
+			i_stream_seek(sync_ctx->input, offset);
 		}
 	}
 
-	trailer_size = i_stream_get_size(sync_ctx.file_input) - offset;
-	if (need_space_seq != 0 && ret >= 0) {
-		i_assert(space_diff < 0);
-		extra_space = MBOX_HEADER_EXTRA_SPACE *
-			(seq - need_space_seq + 1);
-		space_diff -= extra_space;
+	/* rest of the messages in index don't exist -> expunge them */
+	messages_count = mail_index_view_get_message_count(sync_ctx->sync_view);
+	while (sync_ctx->idx_seq < messages_count)
+		mail_index_expunge(sync_ctx->t, ++sync_ctx->idx_seq);
 
-		space_diff += sync_ctx.expunged_space;
-		sync_ctx.expunged_space -= -space_diff;
+	return 0;
+}
 
-		if (mail_ctx.have_eoh && !mail_ctx.updated)
-			str_append_c(mail_ctx.header, '\n');
+static int mbox_sync_handle_eof_updates(struct mbox_sync_context *sync_ctx,
+					struct mbox_sync_mail_context *mail_ctx)
+{
+	uoff_t offset, extra_space, trailer_size;
 
-		if (space_diff < 0 &&
-		    mbox_sync_grow_file(&sync_ctx, &mail_ctx, -space_diff) < 0)
-			ret = -1;
-		else if (mbox_sync_try_rewrite(&mail_ctx, 0) < 0)
-			ret = -1;
-		else if (seq != need_space_seq) {
-			buffer_set_used_size(mails, (seq-need_space_seq) *
-					     sizeof(mail_ctx.mail));
-			buffer_append(mails, &mail_ctx.mail,
-				      sizeof(mail_ctx.mail));
-
-			if (mbox_sync_rewrite(&sync_ctx, mails, need_space_seq,
-					      seq, extra_space) < 0)
-				ret = -1;
-
-			update_from_offsets(ibox, t, mails,
-					    need_space_seq, seq);
-		}
-	}
+	trailer_size = i_stream_get_size(sync_ctx->file_input) -
+		sync_ctx->file_input->v_offset;
 
-	if (sync_ctx.expunged_space > 0) {
-		/* copy trailer, then truncate the file */
-		offset = i_stream_get_size(sync_ctx.file_input) -
-			sync_ctx.expunged_space - trailer_size;
+	if (sync_ctx->need_space_seq != 0) {
+		i_assert(sync_ctx->space_diff < 0);
+		extra_space = MBOX_HEADER_EXTRA_SPACE *
+			(sync_ctx->seq - sync_ctx->need_space_seq + 1);
+		sync_ctx->space_diff -= extra_space;
 
-		if (mbox_move(&sync_ctx, offset,
-			      offset + sync_ctx.expunged_space,
-			      trailer_size) < 0)
-			ret = -1;
-		else if (ftruncate(ibox->mbox_fd, offset + trailer_size) < 0)
-			ret = -1;
+		sync_ctx->space_diff += sync_ctx->expunged_space;
+		sync_ctx->expunged_space -= -sync_ctx->space_diff;
 
-		istream_raw_mbox_flush(input);
-	}
+		if (mail_ctx->have_eoh && !mail_ctx->updated)
+			str_append_c(mail_ctx->header, '\n');
 
-	if (ret >= 0) {
-		if (rec != NULL)
-			mail_index_expunge(t, idx_seq);
-		while (idx_seq < messages_count)
-			mail_index_expunge(t, ++idx_seq);
+		if (sync_ctx->space_diff < 0 &&
+		    mbox_sync_grow_file(sync_ctx, mail_ctx,
+					-sync_ctx->space_diff) < 0)
+			return -1;
 
-		if (sync_ctx.base_uid_last+1 != sync_ctx.next_uid) {
+		if (mbox_sync_try_rewrite(mail_ctx, 0) < 0)
+			return -1;
 
-			// FIXME: rewrite X-IMAPbase header
+		if (sync_ctx->seq != sync_ctx->need_space_seq) {
+			buffer_set_used_size(sync_ctx->mails,
+					     (sync_ctx->seq -
+					      sync_ctx->need_space_seq) *
+					     sizeof(mail_ctx->mail));
+			buffer_append(sync_ctx->mails, &mail_ctx->mail,
+				      sizeof(mail_ctx->mail));
+
+			if (mbox_sync_rewrite(sync_ctx,
+					      sync_ctx->need_space_seq,
+					      sync_ctx->seq, extra_space) < 0)
+				return -1;
+
+			update_from_offsets(sync_ctx->ibox, sync_ctx->t,
+					    sync_ctx->mails,
+					    sync_ctx->need_space_seq,
+					    sync_ctx->seq);
 		}
 	}
 
-	if (ret >= 0) {
-		/* only syncs left should be just appends (and their updates)
-		   which weren't synced yet for some reason (crash). we'll just
-		   ignore them, as we've overwritten them above. */
-		while (mail_index_sync_next(index_sync_ctx, sync_rec) > 0)
-			;
-	}
+	if (sync_ctx->expunged_space > 0) {
+		/* copy trailer, then truncate the file */
+		offset = i_stream_get_size(sync_ctx->file_input) -
+			sync_ctx->expunged_space - trailer_size;
 
-	if (ret == 0) {
-		if (fstat(ibox->mbox_fd, &st) < 0) {
-			mbox_set_syscall_error(ibox, "fstat()");
-			ret = -1;
+		if (mbox_move(sync_ctx, offset,
+			      offset + sync_ctx->expunged_space,
+			      trailer_size) < 0)
+			return -1;
+		if (ftruncate(sync_ctx->ibox->mbox_fd,
+			      offset + trailer_size) < 0) {
+			mbox_set_syscall_error(sync_ctx->ibox, "ftruncate()");
+			return -1;
 		}
+
+		istream_raw_mbox_flush(sync_ctx->input);
 	}
-	if (ret < 0) {
-		st.st_mtime = 0;
-		st.st_size = 0;
+	return 0;
+}
+
+static int mbox_sync_update_index_header(struct mbox_sync_context *sync_ctx)
+{
+	struct stat st;
+
+	if (fstat(sync_ctx->ibox->mbox_fd, &st) < 0) {
+		mbox_set_syscall_error(sync_ctx->ibox, "fstat()");
+		return -1;
 	}
 
-	if (sync_ctx.base_uid_validity != hdr->uid_validity) {
-		mail_index_update_header(t,
+	if (sync_ctx->base_uid_validity != sync_ctx->hdr->uid_validity) {
+		mail_index_update_header(sync_ctx->t,
 			offsetof(struct mail_index_header, uid_validity),
-			&sync_ctx.base_uid_validity,
-			sizeof(sync_ctx.base_uid_validity));
+			&sync_ctx->base_uid_validity,
+			sizeof(sync_ctx->base_uid_validity));
 	}
-	if (sync_ctx.next_uid != hdr->next_uid) {
-		mail_index_update_header(t,
+	if (sync_ctx->next_uid != sync_ctx->hdr->next_uid) {
+		mail_index_update_header(sync_ctx->t,
 			offsetof(struct mail_index_header, next_uid),
-			&sync_ctx.next_uid, sizeof(sync_ctx.next_uid));
+			&sync_ctx->next_uid, sizeof(sync_ctx->next_uid));
 	}
 
-	if ((uint32_t)st.st_mtime != hdr->sync_stamp) {
+	if ((uint32_t)st.st_mtime != sync_ctx->hdr->sync_stamp) {
 		uint32_t sync_stamp = st.st_mtime;
 
-		mail_index_update_header(t,
+		mail_index_update_header(sync_ctx->t,
 			offsetof(struct mail_index_header, sync_stamp),
 			&sync_stamp, sizeof(sync_stamp));
 	}
-	if ((uint64_t)st.st_size != hdr->sync_size) {
+	if ((uint64_t)st.st_size != sync_ctx->hdr->sync_size) {
 		uint64_t sync_size = st.st_size;
 
-		mail_index_update_header(t,
+		mail_index_update_header(sync_ctx->t,
 			offsetof(struct mail_index_header, sync_size),
 			&sync_size, sizeof(sync_size));
 	}
 
-	if (ret < 0)
-		mail_index_transaction_rollback(t);
-	else {
-		if (mail_index_transaction_commit(t, &seq, &offset) < 0)
-			ret = -1;
-		else if (seq != 0) {
-			ibox->commit_log_file_seq = seq;
-			ibox->commit_log_file_offset = offset;
-		}
-	}
+	return 0;
+}
 
-	if (ret != -2) {
-		if (mail_index_sync_end(index_sync_ctx) < 0)
-			ret = -1;
+static void mbox_sync_restart(struct mbox_sync_context *sync_ctx)
+{
+	sync_ctx->base_uid_validity = 0;
+	sync_ctx->base_uid_last = 0;
+
+	sync_ctx->next_uid = 1;
+	sync_ctx->prev_msg_uid = sync_ctx->first_uid = 0;
+	sync_ctx->seq = sync_ctx->idx_seq = 0;
+
+	mail_index_transaction_rollback(sync_ctx->t);
+	sync_ctx->t = mail_index_transaction_begin(sync_ctx->sync_view, FALSE);
+}
+
+static int mbox_sync_do(struct mbox_sync_context *sync_ctx, int index_synced)
+{
+	struct index_mailbox *ibox = sync_ctx->ibox;
+	struct mbox_sync_mail_context mail_ctx;
+	int ret, lock_type;
+
+	lock_type = mail_index_sync_have_more(sync_ctx->index_sync_ctx) ?
+		F_WRLCK : F_RDLCK;
+	if ((ret = mbox_lock(ibox, lock_type, &sync_ctx->lock_id)) <= 0)
+		return ret;
+
+	if (mbox_file_open_stream(ibox) < 0)
+		return -1;
+
+	if ((ret = mbox_sync_parse_all(sync_ctx, &mail_ctx)) == -1)
+		return -1;
+
+	if (ret == -2) {
+		/* we want to modify mbox, get exclusive lock. this requires
+		   dropping the read lock first, so we have to parse the whole
+		   mbox again */
+		(void)mbox_unlock(ibox, sync_ctx->lock_id);
+		sync_ctx->lock_id = 0;
+
+		if ((ret = mbox_lock(ibox, F_WRLCK, &sync_ctx->lock_id)) <= 0)
+			return ret;
+		if (mbox_file_open_stream(ibox) < 0)
+			return -1;
+
+		/* FIXME: if mbox timestamp hasn't changed and it's older than
+		   2 secs, we could continue from where we left */
+		mbox_sync_restart(sync_ctx);
+
+		if (mbox_sync_parse_all(sync_ctx, &mail_ctx) < 0)
+			return -1;
 	}
 
-	if (ret == 0) {
-		ibox->commit_log_file_seq = 0;
-		ibox->commit_log_file_offset = 0;
-	} else {
-		mail_storage_set_index_error(ibox);
+	if (mbox_sync_handle_eof_updates(sync_ctx, &mail_ctx) < 0)
+		return -1;
+
+	if (sync_ctx->base_uid_last+1 != sync_ctx->next_uid) {
+		// FIXME: rewrite X-IMAPbase header
 	}
 
-	str_free(sync_ctx.header);
-	str_free(sync_ctx.from_line);
-	buffer_free(mails);
-	return ret < 0 ? ret : 0;
+	/* only syncs left should be just appends (and their updates)
+	   which weren't synced yet for some reason (crash). we'll just
+	   ignore them, as we've overwritten them above. */
+	while (mail_index_sync_next(sync_ctx->index_sync_ctx,
+				    &sync_ctx->sync_rec) > 0)
+		;
+
+	if (mbox_sync_update_index_header(sync_ctx) < 0)
+		return -1;
+
+	return 0;
 }
 
 static int mbox_sync_has_changed(struct index_mailbox *ibox)
@@ -688,12 +767,10 @@ int mbox_sync(struct index_mailbox *ibox, int last_commit)
 {
 	struct mail_index_sync_ctx *index_sync_ctx;
 	struct mail_index_view *sync_view;
-	unsigned int lock_id;
+	struct mbox_sync_context sync_ctx;
 	uint32_t seq;
 	uoff_t offset;
-	struct mail_index_sync_rec sync_rec;
-	buffer_t *syncs;
-	int ret, lock_type, index_synced;
+	int ret, index_synced;
 
 	if ((ret = mbox_sync_has_changed(ibox)) < 0)
 		return -1;
@@ -717,40 +794,46 @@ int mbox_sync(struct index_mailbox *ibox, int last_commit)
 		return ret;
 	}
 
-	memset(&sync_rec, 0, sizeof(sync_rec));
-	syncs = buffer_create_dynamic(default_pool, 256, (size_t)-1);
+	memset(&sync_ctx, 0, sizeof(sync_ctx));
+	sync_ctx.ibox = ibox;
+	sync_ctx.from_line = str_new(default_pool, 256);
+	sync_ctx.header = str_new(default_pool, 4096);
+
+	sync_ctx.index_sync_ctx = index_sync_ctx;
+	sync_ctx.sync_view = sync_view;
+	sync_ctx.t = mail_index_transaction_begin(sync_view, FALSE);
 
-	lock_type = mail_index_sync_have_more(index_sync_ctx) ?
-		F_WRLCK : F_RDLCK;
-	if (mbox_lock(ibox, lock_type, &lock_id) > 0 &&
-	    mbox_file_open_stream(ibox) == 0) {
-		ret = mbox_sync_do(ibox, index_sync_ctx, sync_view,
-				   syncs, &sync_rec, index_synced);
-		if (ret == -2) {
-			/* read lock -> write lock. do it again. */
-			(void)mbox_unlock(ibox, lock_id);
-			lock_id = 0;
-			if (mbox_lock(ibox, F_WRLCK, &lock_id) <= 0)
-				ret = -1;
-			else if (mbox_file_open_stream(ibox) < 0)
-				ret = -1;
-			else {
-				ret = mbox_sync_do(ibox, index_sync_ctx,
-						   sync_view, syncs, &sync_rec,
-						   FALSE);
-			}
-		}
-	} else {
-		(void)mail_index_sync_end(index_sync_ctx);
+	sync_ctx.mails = buffer_create_dynamic(default_pool, 4096, (size_t)-1);
+	sync_ctx.syncs = buffer_create_dynamic(default_pool, 256, (size_t)-1);
+	sync_ctx.next_uid = 1;
+
+	ret = mail_index_get_header(sync_view, &sync_ctx.hdr);
+	i_assert(ret == 0);
+
+	if (mbox_sync_do(&sync_ctx, index_synced) < 0)
 		ret = -1;
+
+	if (ret < 0)
+		mail_index_transaction_rollback(sync_ctx.t);
+	else if (mail_index_transaction_commit(sync_ctx.t, &seq, &offset) < 0)
+		ret = -1;
+	else {
+		ibox->commit_log_file_seq = 0;
+		ibox->commit_log_file_offset = 0;
 	}
 
-	if (lock_id != 0) {
-		if (mbox_unlock(ibox, lock_id) < 0)
+	if (mail_index_sync_end(index_sync_ctx) < 0)
+		ret = -1;
+
+	if (sync_ctx.lock_id != 0) {
+		if (mbox_unlock(ibox, sync_ctx.lock_id) < 0)
 			ret = -1;
 	}
 
-	buffer_free(syncs);
+	str_free(sync_ctx.header);
+	str_free(sync_ctx.from_line);
+	buffer_free(sync_ctx.mails);
+	buffer_free(sync_ctx.syncs);
 	return ret;
 }