From: Timo Sirainen <timo.sirainen@dovecot.fi>
Date: Fri, 3 Jun 2016 14:54:36 +0000 (+0300)
Subject: lib-index: Allow growing ext record_size after mail_index_update_ext()
X-Git-Tag: 2.2.25.rc1~194
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e6696669bff159e93dc040f1c8574e938348353c;p=thirdparty%2Fdovecot%2Fcore.git

lib-index: Allow growing ext record_size after mail_index_update_ext()

The existing records will just get some zero-padding at the end of records.
---

diff --git a/src/lib-index/mail-index-transaction-update.c b/src/lib-index/mail-index-transaction-update.c
index ac1cf62bc5..38f9905b97 100644
--- a/src/lib-index/mail-index-transaction-update.c
+++ b/src/lib-index/mail-index-transaction-update.c
@@ -713,6 +713,33 @@ void mail_index_update_header(struct mail_index_transaction *t,
 	}
 }
 
+static void
+mail_index_ext_rec_updates_resize(struct mail_index_transaction *t,
+				  uint32_t ext_id, uint16_t new_record_size)
+{
+	ARRAY_TYPE(seq_array) *array, old_array;
+	unsigned int i;
+
+	if (!array_is_created(&t->ext_rec_updates))
+		return;
+	array = array_idx_modifiable(&t->ext_rec_updates, ext_id);
+	if (!array_is_created(array))
+		return;
+
+	old_array = *array;
+	memset(array, 0, sizeof(*array));
+	mail_index_seq_array_alloc(array, new_record_size);
+
+	/* copy the records' beginnings. leave the end zero-filled. */
+	for (i = 0; i < array_count(&old_array); i++) {
+		const void *old_record = array_idx(&old_array, i);
+
+		memcpy(array_append_space(array), old_record,
+		       old_array.arr.element_size);
+	}
+	array_free(&old_array);
+}
+
 void mail_index_ext_resize(struct mail_index_transaction *t, uint32_t ext_id,
 			   uint32_t hdr_size, uint16_t record_size,
 			   uint16_t record_align)
@@ -741,12 +768,13 @@ void mail_index_ext_resize(struct mail_index_transaction *t, uint32_t ext_id,
 		old_header_size = ext->hdr_size;
 	}
 
-	/* allow only header size changes if extension records have already
-	   been changed in transaction */
-	i_assert(!array_is_created(&t->ext_rec_updates) ||
-		 record_size == (uint16_t)-1 ||
-		 (old_record_size == record_size &&
-		  old_record_align == record_align));
+	if (record_size != old_record_size) {
+		/* if record_size grows, we'll just resize the existing
+		   ext_rec_updates array. it's not possible to shrink
+		   record_size without data loss. */
+		i_assert(record_size > old_record_size);
+		mail_index_ext_rec_updates_resize(t, ext_id, record_size);
+	}
 
 	t->log_ext_updates = TRUE;
 
diff --git a/src/lib-index/mail-index-util.c b/src/lib-index/mail-index-util.c
index b633539588..659d622764 100644
--- a/src/lib-index/mail-index-util.c
+++ b/src/lib-index/mail-index-util.c
@@ -116,6 +116,18 @@ bool mail_index_seq_array_lookup(const ARRAY_TYPE(seq_array) *array,
 					mail_index_seq_record_cmp, idx_r);
 }
 
+void mail_index_seq_array_alloc(ARRAY_TYPE(seq_array) *array,
+				size_t record_size)
+{
+	size_t aligned_record_size = (record_size + 3) & ~3;
+
+	i_assert(!array_is_created(array));
+
+	array_create(array, default_pool,
+		     sizeof(uint32_t) + aligned_record_size,
+		     1024 / (sizeof(uint32_t) + aligned_record_size));
+}
+
 bool mail_index_seq_array_add(ARRAY_TYPE(seq_array) *array, uint32_t seq,
 			      const void *record, size_t record_size,
 			      void *old_record)
@@ -126,11 +138,8 @@ bool mail_index_seq_array_add(ARRAY_TYPE(seq_array) *array, uint32_t seq,
 	/* records need to be 32bit aligned */
 	aligned_record_size = (record_size + 3) & ~3;
 
-	if (!array_is_created(array)) {
-		array_create(array, default_pool,
-			     sizeof(seq) + aligned_record_size,
-			     1024 / (sizeof(seq) + aligned_record_size));
-	}
+	if (!array_is_created(array))
+		mail_index_seq_array_alloc(array, record_size);
 	i_assert(array->arr.element_size == sizeof(seq) + aligned_record_size);
 
 	if (mail_index_seq_array_lookup(array, seq, &idx)) {
diff --git a/src/lib-index/mail-index-util.h b/src/lib-index/mail-index-util.h
index eeb17e9499..b61e16a23a 100644
--- a/src/lib-index/mail-index-util.h
+++ b/src/lib-index/mail-index-util.h
@@ -13,6 +13,8 @@ int mail_index_unpack_num(const uint8_t **p, const uint8_t *end,
 
 bool mail_index_seq_array_lookup(const ARRAY_TYPE(seq_array) *array,
 				 uint32_t seq, unsigned int *idx_r);
+void mail_index_seq_array_alloc(ARRAY_TYPE(seq_array) *array,
+				size_t record_size);
 bool mail_index_seq_array_add(ARRAY_TYPE(seq_array) *array, uint32_t seq,
 			      const void *record, size_t record_size,
 			      void *old_record) ATTR_NULL(5);