PLT-3105 Files table migration (#4068)

* Implemented initial changes for files table

* Removed *_benchmark_test.go files

* Re-implemented GetPublicFile and added support for old path

* Localization for files table

* Moved file system code into utils package

* Finished server-side changes and added initial upgrade script

* Added getPostFiles api

* Re-add Extension and HasPreviewImage fields to FileInfo

* Removed unused translation

* Fixed merge conflicts left over after permissions changes

* Forced FileInfo.extension to be lower case

* Changed FileUploadResponse to contain the FileInfos instead of FileIds

* Fixed permissions on getFile* calls

* Fixed notifications for file uploads

* Added initial version of client code for files changes

* Permanently added FileIds field to Post object and removed Post.HasFiles

* Updated PostStore.Update to be usable in more circumstances

* Re-added Filenames field and switched file migration to be entirely lazy-loaded

* Increased max listener count for FileStore

* Removed unused fileInfoCache

* Moved file system code back into api

* Removed duplicate test case

* Fixed unit test running on ports other than 8065

* Renamed HasPermissionToPostContext to HasPermissionToChannelByPostContext

* Refactored handleImages to make it more easily understandable

* Renamed getPostFiles to getFileInfosForPost

* Re-added pre-FileIds posts to analytics

* Changed files to be saved as their ids as opposed to id/filename.ext

* Renamed FileInfo.UserId to FileInfo.CreatorId

* Fixed detection of language in CodePreview

* Fixed switching between threads in the RHS not loading new files

* Add serverside protection against a rare bug where the client sends the same file twice for a single post

* Refactored the important parts of uploadFile api call into a function that can be called without a web context

10 files changed, 600 insertions, 33 deletions

diff --git a/store/sql_channel_store.go b/store/sql_channel_store.go
index 99a36b1cd..07c037075 100644
--- a/store/sql_channel_store.go
+++ b/store/sql_channel_store.go
@@ -596,6 +596,36 @@ func (s SqlChannelStore) GetMember(channelId string, userId string) StoreChannel
 	return storeChannel
 }
 
+func (s SqlChannelStore) GetMemberForPost(postId string, userId string) StoreChannel {
+	storeChannel := make(StoreChannel, 1)
+
+	go func() {
+		result := StoreResult{}
+
+		member := &model.ChannelMember{}
+		if err := s.GetReplica().SelectOne(
+			member,
+			`SELECT
+				ChannelMembers.*
+			FROM
+				ChannelMembers,
+				Posts
+			WHERE
+				ChannelMembers.ChannelId = Posts.ChannelId
+				AND ChannelMembers.UserId = :UserId
+				AND Posts.Id = :PostId`, map[string]interface{}{"UserId": userId, "PostId": postId}); err != nil {
+			result.Err = model.NewLocAppError("SqlChannelStore.GetMemberForPost", "store.sql_channel.get_member_for_post.app_error", nil, "postId="+postId+", err="+err.Error())
+		} else {
+			result.Data = member
+		}
+
+		storeChannel <- result
+		close(storeChannel)
+	}()
+
+	return storeChannel
+}
+
 func (s SqlChannelStore) GetMemberCount(channelId string) StoreChannel {
 	storeChannel := make(StoreChannel, 1)
 
@@ -878,6 +908,35 @@ func (s SqlChannelStore) GetAll(teamId string) StoreChannel {
 	return storeChannel
 }
 
+func (s SqlChannelStore) GetForPost(postId string) StoreChannel {
+	storeChannel := make(StoreChannel, 1)
+
+	go func() {
+		result := StoreResult{}
+
+		channel := &model.Channel{}
+		if err := s.GetReplica().SelectOne(
+			channel,
+			`SELECT
+				Channels.*
+			FROM
+				Channels,
+				Posts
+			WHERE
+				Channels.Id = Posts.ChannelId
+				AND Posts.Id = :PostId`, map[string]interface{}{"PostId": postId}); err != nil {
+			result.Err = model.NewLocAppError("SqlChannelStore.GetForPost", "store.sql_channel.get_for_post.app_error", nil, "postId="+postId+", err="+err.Error())
+		} else {
+			result.Data = channel
+		}
+
+		storeChannel <- result
+		close(storeChannel)
+	}()
+
+	return storeChannel
+}
+
 func (s SqlChannelStore) AnalyticsTypeCount(teamId string, channelType string) StoreChannel {
 	storeChannel := make(StoreChannel, 1)
 
diff --git a/store/sql_channel_store_test.go b/store/sql_channel_store_test.go
index d7d99f581..0bd059e5f 100644
--- a/store/sql_channel_store_test.go
+++ b/store/sql_channel_store_test.go
@@ -197,6 +197,29 @@ func TestChannelStoreGet(t *testing.T) {
 	}
 }
 
+func TestChannelStoreGetForPost(t *testing.T) {
+	Setup()
+
+	o1 := Must(store.Channel().Save(&model.Channel{
+		TeamId:      model.NewId(),
+		DisplayName: "Name",
+		Name:        "a" + model.NewId() + "b",
+		Type:        model.CHANNEL_OPEN,
+	})).(*model.Channel)
+
+	p1 := Must(store.Post().Save(&model.Post{
+		UserId:    model.NewId(),
+		ChannelId: o1.Id,
+		Message:   "test",
+	})).(*model.Post)
+
+	if r1 := <-store.Channel().GetForPost(p1.Id); r1.Err != nil {
+		t.Fatal(r1.Err)
+	} else if r1.Data.(*model.Channel).Id != o1.Id {
+		t.Fatal("incorrect channel returned")
+	}
+}
+
 func TestChannelStoreDelete(t *testing.T) {
 	Setup()
 
@@ -745,6 +768,39 @@ func TestGetMember(t *testing.T) {
 	}
 }
 
+func TestChannelStoreGetMemberForPost(t *testing.T) {
+	Setup()
+
+	o1 := Must(store.Channel().Save(&model.Channel{
+		TeamId:      model.NewId(),
+		DisplayName: "Name",
+		Name:        "a" + model.NewId() + "b",
+		Type:        model.CHANNEL_OPEN,
+	})).(*model.Channel)
+
+	m1 := Must(store.Channel().SaveMember(&model.ChannelMember{
+		ChannelId:   o1.Id,
+		UserId:      model.NewId(),
+		NotifyProps: model.GetDefaultChannelNotifyProps(),
+	})).(*model.ChannelMember)
+
+	p1 := Must(store.Post().Save(&model.Post{
+		UserId:    model.NewId(),
+		ChannelId: o1.Id,
+		Message:   "test",
+	})).(*model.Post)
+
+	if r1 := <-store.Channel().GetMemberForPost(p1.Id, m1.UserId); r1.Err != nil {
+		t.Fatal(r1.Err)
+	} else if r1.Data.(*model.ChannelMember).ToJson() != m1.ToJson() {
+		t.Fatal("invalid returned channel member")
+	}
+
+	if r2 := <-store.Channel().GetMemberForPost(p1.Id, model.NewId()); r2.Err == nil {
+		t.Fatal("shouldn't have returned a member")
+	}
+}
+
 func TestGetMemberCount(t *testing.T) {
 	Setup()
 
diff --git a/store/sql_compliance_store.go b/store/sql_compliance_store.go
index 6aaef856d..0a131d289 100644
--- a/store/sql_compliance_store.go
+++ b/store/sql_compliance_store.go
@@ -199,7 +199,7 @@ func (s SqlComplianceStore) ComplianceExport(job *model.Compliance) StoreChannel
 			    Posts.Type AS PostType,
 			    Posts.Props AS PostProps,
 			    Posts.Hashtags AS PostHashtags,
-			    Posts.Filenames AS PostFilenames
+			    Posts.FileIds AS PostFileIds
 			FROM
 			    Teams,
 			    Channels,
diff --git a/store/sql_file_info_store.go b/store/sql_file_info_store.go
new file mode 100644
index 000000000..5c3f6b1a4
--- /dev/null
+++ b/store/sql_file_info_store.go
@@ -0,0 +1,197 @@
+// See License.txt for license information.
+
+package store
+
+import (
+	"github.com/mattermost/platform/model"
+)
+
+type SqlFileInfoStore struct {
+	*SqlStore
+}
+
+func NewSqlFileInfoStore(sqlStore *SqlStore) FileInfoStore {
+	s := &SqlFileInfoStore{sqlStore}
+
+	for _, db := range sqlStore.GetAllConns() {
+		table := db.AddTableWithName(model.FileInfo{}, "FileInfo").SetKeys(false, "Id")
+		table.ColMap("Id").SetMaxSize(26)
+		table.ColMap("CreatorId").SetMaxSize(26)
+		table.ColMap("PostId").SetMaxSize(26)
+		table.ColMap("Path").SetMaxSize(512)
+		table.ColMap("ThumbnailPath").SetMaxSize(512)
+		table.ColMap("PreviewPath").SetMaxSize(512)
+		table.ColMap("Name").SetMaxSize(256)
+		table.ColMap("Extension").SetMaxSize(64)
+		table.ColMap("MimeType").SetMaxSize(256)
+	}
+
+	return s
+}
+
+func (fs SqlFileInfoStore) CreateIndexesIfNotExists() {
+}
+
+func (fs SqlFileInfoStore) Save(info *model.FileInfo) StoreChannel {
+	storeChannel := make(StoreChannel, 1)
+
+	go func() {
+		result := StoreResult{}
+
+		info.PreSave()
+		if result.Err = info.IsValid(); result.Err != nil {
+			storeChannel <- result
+			close(storeChannel)
+			return
+		}
+
+		if err := fs.GetMaster().Insert(info); err != nil {
+			result.Err = model.NewLocAppError("SqlFileInfoStore.Save", "store.sql_file_info.save.app_error", nil, err.Error())
+		} else {
+			result.Data = info
+		}
+
+		storeChannel <- result
+		close(storeChannel)
+	}()
+
+	return storeChannel
+}
+
+func (fs SqlFileInfoStore) Get(id string) StoreChannel {
+	storeChannel := make(StoreChannel, 1)
+
+	go func() {
+		result := StoreResult{}
+
+		info := &model.FileInfo{}
+
+		if err := fs.GetReplica().SelectOne(info,
+			`SELECT
+				*
+			FROM
+				FileInfo
+			WHERE
+				Id = :Id
+				AND DeleteAt = 0`, map[string]interface{}{"Id": id}); err != nil {
+			result.Err = model.NewLocAppError("SqlFileInfoStore.Get", "store.sql_file_info.get.app_error", nil, "id="+id+", "+err.Error())
+		} else {
+			result.Data = info
+		}
+
+		storeChannel <- result
+		close(storeChannel)
+	}()
+
+	return storeChannel
+}
+
+func (fs SqlFileInfoStore) GetByPath(path string) StoreChannel {
+	storeChannel := make(StoreChannel, 1)
+
+	go func() {
+		result := StoreResult{}
+
+		info := &model.FileInfo{}
+
+		if err := fs.GetReplica().SelectOne(info,
+			`SELECT
+				*
+			FROM
+				FileInfo
+			WHERE
+				Path = :Path
+				AND DeleteAt = 0`, map[string]interface{}{"Path": path}); err != nil {
+			result.Err = model.NewLocAppError("SqlFileInfoStore.GetByPath", "store.sql_file_info.get_by_path.app_error", nil, "path="+path+", "+err.Error())
+		} else {
+			result.Data = info
+		}
+
+		storeChannel <- result
+		close(storeChannel)
+	}()
+
+	return storeChannel
+}
+
+func (fs SqlFileInfoStore) GetForPost(postId string) StoreChannel {
+	storeChannel := make(StoreChannel, 1)
+
+	go func() {
+		result := StoreResult{}
+
+		var infos []*model.FileInfo
+
+		if _, err := fs.GetReplica().Select(&infos,
+			`SELECT
+				*
+			FROM
+				FileInfo
+			WHERE
+				PostId = :PostId
+				AND DeleteAt = 0
+			ORDER BY
+				CreateAt`, map[string]interface{}{"PostId": postId}); err != nil {
+			result.Err = model.NewLocAppError("SqlFileInfoStore.GetForPost",
+				"store.sql_file_info.get_for_post.app_error", nil, "post_id="+postId+", "+err.Error())
+		} else {
+			result.Data = infos
+		}
+
+		storeChannel <- result
+		close(storeChannel)
+	}()
+
+	return storeChannel
+}
+
+func (fs SqlFileInfoStore) AttachToPost(fileId, postId string) StoreChannel {
+	storeChannel := make(StoreChannel, 1)
+
+	go func() {
+		result := StoreResult{}
+
+		if _, err := fs.GetMaster().Exec(
+			`UPDATE
+					FileInfo
+				SET
+					PostId = :PostId
+				WHERE
+					Id = :Id
+					AND PostId = ''`, map[string]interface{}{"PostId": postId, "Id": fileId}); err != nil {
+			result.Err = model.NewLocAppError("SqlFileInfoStore.AttachToPost",
+				"store.sql_file_info.attach_to_post.app_error", nil, "post_id="+postId+", file_id="+fileId+", err="+err.Error())
+		}
+
+		storeChannel <- result
+		close(storeChannel)
+	}()
+
+	return storeChannel
+}
+
+func (fs SqlFileInfoStore) DeleteForPost(postId string) StoreChannel {
+	storeChannel := make(StoreChannel, 1)
+
+	go func() {
+		result := StoreResult{}
+
+		if _, err := fs.GetMaster().Exec(
+			`UPDATE
+				FileInfo
+			SET
+				DeleteAt = :DeleteAt
+			WHERE
+				PostId = :PostId`, map[string]interface{}{"DeleteAt": model.GetMillis(), "PostId": postId}); err != nil {
+			result.Err = model.NewLocAppError("SqlFileInfoStore.DeleteForPost",
+				"store.sql_file_info.delete_for_post.app_error", nil, "post_id="+postId+", err="+err.Error())
+		} else {
+			result.Data = postId
+		}
+
+		storeChannel <- result
+		close(storeChannel)
+	}()
+
+	return storeChannel
+}
diff --git a/store/sql_file_info_store_test.go b/store/sql_file_info_store_test.go
new file mode 100644
index 000000000..edb9dbd54
--- /dev/null
+++ b/store/sql_file_info_store_test.go
@@ -0,0 +1,208 @@
+// Copyright (c) 2016 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package store
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/mattermost/platform/model"
+)
+
+func TestFileInfoSaveGet(t *testing.T) {
+	Setup()
+
+	info := &model.FileInfo{
+		CreatorId: model.NewId(),
+		Path:      "file.txt",
+	}
+
+	if result := <-store.FileInfo().Save(info); result.Err != nil {
+		t.Fatal(result.Err)
+	} else if returned := result.Data.(*model.FileInfo); len(returned.Id) == 0 {
+		t.Fatal("should've assigned an id to FileInfo")
+	} else {
+		info = returned
+	}
+
+	if result := <-store.FileInfo().Get(info.Id); result.Err != nil {
+		t.Fatal(result.Err)
+	} else if returned := result.Data.(*model.FileInfo); returned.Id != info.Id {
+		t.Log(info)
+		t.Log(returned)
+		t.Fatal("should've returned correct FileInfo")
+	}
+
+	info2 := Must(store.FileInfo().Save(&model.FileInfo{
+		CreatorId: model.NewId(),
+		Path:      "file.txt",
+		DeleteAt:  123,
+	})).(*model.FileInfo)
+
+	if result := <-store.FileInfo().Get(info2.Id); result.Err == nil {
+		t.Fatal("shouldn't have gotten deleted file")
+	}
+}
+
+func TestFileInfoSaveGetByPath(t *testing.T) {
+	Setup()
+
+	info := &model.FileInfo{
+		CreatorId: model.NewId(),
+		Path:      fmt.Sprintf("%v/file.txt", model.NewId()),
+	}
+
+	if result := <-store.FileInfo().Save(info); result.Err != nil {
+		t.Fatal(result.Err)
+	} else if returned := result.Data.(*model.FileInfo); len(returned.Id) == 0 {
+		t.Fatal("should've assigned an id to FileInfo")
+	} else {
+		info = returned
+	}
+
+	if result := <-store.FileInfo().GetByPath(info.Path); result.Err != nil {
+		t.Fatal(result.Err)
+	} else if returned := result.Data.(*model.FileInfo); returned.Id != info.Id {
+		t.Log(info)
+		t.Log(returned)
+		t.Fatal("should've returned correct FileInfo")
+	}
+
+	info2 := Must(store.FileInfo().Save(&model.FileInfo{
+		CreatorId: model.NewId(),
+		Path:      "file.txt",
+		DeleteAt:  123,
+	})).(*model.FileInfo)
+
+	if result := <-store.FileInfo().GetByPath(info2.Id); result.Err == nil {
+		t.Fatal("shouldn't have gotten deleted file")
+	}
+}
+
+func TestFileInfoGetForPost(t *testing.T) {
+	Setup()
+
+	userId := model.NewId()
+	postId := model.NewId()
+
+	infos := []*model.FileInfo{
+		{
+			PostId:    postId,
+			CreatorId: userId,
+			Path:      "file.txt",
+		},
+		{
+			PostId:    postId,
+			CreatorId: userId,
+			Path:      "file.txt",
+		},
+		{
+			PostId:    postId,
+			CreatorId: userId,
+			Path:      "file.txt",
+			DeleteAt:  123,
+		},
+		{
+			PostId:    model.NewId(),
+			CreatorId: userId,
+			Path:      "file.txt",
+		},
+	}
+
+	for i, info := range infos {
+		infos[i] = Must(store.FileInfo().Save(info)).(*model.FileInfo)
+	}
+
+	if result := <-store.FileInfo().GetForPost(postId); result.Err != nil {
+		t.Fatal(result.Err)
+	} else if returned := result.Data.([]*model.FileInfo); len(returned) != 2 {
+		t.Fatal("should've returned exactly 2 file infos")
+	}
+}
+
+func TestFileInfoAttachToPost(t *testing.T) {
+	Setup()
+
+	userId := model.NewId()
+	postId := model.NewId()
+
+	info1 := Must(store.FileInfo().Save(&model.FileInfo{
+		CreatorId: userId,
+		Path:      "file.txt",
+	})).(*model.FileInfo)
+
+	if len(info1.PostId) != 0 {
+		t.Fatal("file shouldn't have a PostId")
+	}
+
+	if result := <-store.FileInfo().AttachToPost(info1.Id, postId); result.Err != nil {
+		t.Fatal(result.Err)
+	} else {
+		info1 = Must(store.FileInfo().Get(info1.Id)).(*model.FileInfo)
+	}
+
+	if len(info1.PostId) == 0 {
+		t.Fatal("file should now have a PostId")
+	}
+
+	info2 := Must(store.FileInfo().Save(&model.FileInfo{
+		CreatorId: userId,
+		Path:      "file.txt",
+	})).(*model.FileInfo)
+
+	if result := <-store.FileInfo().AttachToPost(info2.Id, postId); result.Err != nil {
+		t.Fatal(result.Err)
+	} else {
+		info2 = Must(store.FileInfo().Get(info2.Id)).(*model.FileInfo)
+	}
+
+	if result := <-store.FileInfo().GetForPost(postId); result.Err != nil {
+		t.Fatal(result.Err)
+	} else if infos := result.Data.([]*model.FileInfo); len(infos) != 2 {
+		t.Fatal("should've returned exactly 2 file infos")
+	}
+}
+
+func TestFileInfoDeleteForPost(t *testing.T) {
+	Setup()
+
+	userId := model.NewId()
+	postId := model.NewId()
+
+	infos := []*model.FileInfo{
+		{
+			PostId:    postId,
+			CreatorId: userId,
+			Path:      "file.txt",
+		},
+		{
+			PostId:    postId,
+			CreatorId: userId,
+			Path:      "file.txt",
+		},
+		{
+			PostId:    postId,
+			CreatorId: userId,
+			Path:      "file.txt",
+			DeleteAt:  123,
+		},
+		{
+			PostId:    model.NewId(),
+			CreatorId: userId,
+			Path:      "file.txt",
+		},
+	}
+
+	for i, info := range infos {
+		infos[i] = Must(store.FileInfo().Save(info)).(*model.FileInfo)
+	}
+
+	if result := <-store.FileInfo().DeleteForPost(postId); result.Err != nil {
+		t.Fatal(result.Err)
+	}
+
+	if infos := Must(store.FileInfo().GetForPost(postId)).([]*model.FileInfo); len(infos) != 0 {
+		t.Fatal("shouldn't have returned any file infos")
+	}
+}
diff --git a/store/sql_post_store.go b/store/sql_post_store.go
index 212492df0..ec8679b31 100644
--- a/store/sql_post_store.go
+++ b/store/sql_post_store.go
@@ -32,6 +32,7 @@ func NewSqlPostStore(sqlStore *SqlStore) PostStore {
 		table.ColMap("Hashtags").SetMaxSize(1000)
 		table.ColMap("Props").SetMaxSize(8000)
 		table.ColMap("Filenames").SetMaxSize(4000)
+		table.ColMap("FileIds").SetMaxSize(150)
 	}
 
 	return s
@@ -94,42 +95,39 @@ func (s SqlPostStore) Save(post *model.Post) StoreChannel {
 	return storeChannel
 }
 
-func (s SqlPostStore) Update(oldPost *model.Post, newMessage string, newHashtags string) StoreChannel {
+func (s SqlPostStore) Update(newPost *model.Post, oldPost *model.Post) StoreChannel {
 	storeChannel := make(StoreChannel, 1)
 
 	go func() {
 		result := StoreResult{}
 
-		editPost := *oldPost
-		editPost.Message = newMessage
-		editPost.UpdateAt = model.GetMillis()
-		editPost.Hashtags = newHashtags
+		newPost.UpdateAt = model.GetMillis()
 
-		oldPost.DeleteAt = editPost.UpdateAt
-		oldPost.UpdateAt = editPost.UpdateAt
+		oldPost.DeleteAt = newPost.UpdateAt
+		oldPost.UpdateAt = newPost.UpdateAt
 		oldPost.OriginalId = oldPost.Id
 		oldPost.Id = model.NewId()
 
-		if result.Err = editPost.IsValid(); result.Err != nil {
+		if result.Err = newPost.IsValid(); result.Err != nil {
 			storeChannel <- result
 			close(storeChannel)
 			return
 		}
 
-		if _, err := s.GetMaster().Update(&editPost); err != nil {
-			result.Err = model.NewLocAppError("SqlPostStore.Update", "store.sql_post.update.app_error", nil, "id="+editPost.Id+", "+err.Error())
+		if _, err := s.GetMaster().Update(newPost); err != nil {
+			result.Err = model.NewLocAppError("SqlPostStore.Update", "store.sql_post.update.app_error", nil, "id="+newPost.Id+", "+err.Error())
 		} else {
 			time := model.GetMillis()
-			s.GetMaster().Exec("UPDATE Channels SET LastPostAt = :LastPostAt  WHERE Id = :ChannelId", map[string]interface{}{"LastPostAt": time, "ChannelId": editPost.ChannelId})
+			s.GetMaster().Exec("UPDATE Channels SET LastPostAt = :LastPostAt  WHERE Id = :ChannelId", map[string]interface{}{"LastPostAt": time, "ChannelId": newPost.ChannelId})
 
-			if len(editPost.RootId) > 0 {
-				s.GetMaster().Exec("UPDATE Posts SET UpdateAt = :UpdateAt WHERE Id = :RootId", map[string]interface{}{"UpdateAt": time, "RootId": editPost.RootId})
+			if len(newPost.RootId) > 0 {
+				s.GetMaster().Exec("UPDATE Posts SET UpdateAt = :UpdateAt WHERE Id = :RootId", map[string]interface{}{"UpdateAt": time, "RootId": newPost.RootId})
 			}
 
 			// mark the old post as deleted
 			s.GetMaster().Insert(oldPost)
 
-			result.Data = &editPost
+			result.Data = newPost
 		}
 
 		storeChannel <- result
@@ -972,7 +970,7 @@ func (s SqlPostStore) AnalyticsPostCount(teamId string, mustHaveFile bool, mustH
 		}
 
 		if mustHaveFile {
-			query += " AND Posts.Filenames != '[]'"
+			query += " AND (Posts.FileIds != '[]' OR Posts.Filenames != '[]')"
 		}
 
 		if mustHaveHashtag {
diff --git a/store/sql_post_store_test.go b/store/sql_post_store_test.go
index 6105cbace..d685ea41e 100644
--- a/store/sql_post_store_test.go
+++ b/store/sql_post_store_test.go
@@ -87,45 +87,73 @@ func TestPostStoreUpdate(t *testing.T) {
 
 	ro1 := (<-store.Post().Get(o1.Id)).Data.(*model.PostList).Posts[o1.Id]
 	ro2 := (<-store.Post().Get(o1.Id)).Data.(*model.PostList).Posts[o2.Id]
-	ro6 := (<-store.Post().Get(o3.Id)).Data.(*model.PostList).Posts[o3.Id]
+	ro3 := (<-store.Post().Get(o3.Id)).Data.(*model.PostList).Posts[o3.Id]
 
 	if ro1.Message != o1.Message {
 		t.Fatal("Failed to save/get")
 	}
 
-	msg := o1.Message + "BBBBBBBBBB"
-	if result := <-store.Post().Update(ro1, msg, ""); result.Err != nil {
+	o1a := &model.Post{}
+	*o1a = *ro1
+	o1a.Message = ro1.Message + "BBBBBBBBBB"
+	if result := <-store.Post().Update(o1a, ro1); result.Err != nil {
 		t.Fatal(result.Err)
 	}
 
-	msg2 := o2.Message + "DDDDDDD"
-	if result := <-store.Post().Update(ro2, msg2, ""); result.Err != nil {
-		t.Fatal(result.Err)
+	ro1a := (<-store.Post().Get(o1.Id)).Data.(*model.PostList).Posts[o1.Id]
+
+	if ro1a.Message != o1a.Message {
+		t.Fatal("Failed to update/get")
 	}
 
-	msg3 := o3.Message + "WWWWWWW"
-	if result := <-store.Post().Update(ro6, msg3, "#hashtag"); result.Err != nil {
+	o2a := &model.Post{}
+	*o2a = *ro2
+	o2a.Message = ro2.Message + "DDDDDDD"
+	if result := <-store.Post().Update(o2a, ro2); result.Err != nil {
 		t.Fatal(result.Err)
 	}
 
-	ro3 := (<-store.Post().Get(o1.Id)).Data.(*model.PostList).Posts[o1.Id]
+	ro2a := (<-store.Post().Get(o1.Id)).Data.(*model.PostList).Posts[o2.Id]
 
-	if ro3.Message != msg {
+	if ro2a.Message != o2a.Message {
 		t.Fatal("Failed to update/get")
 	}
 
-	ro4 := (<-store.Post().Get(o1.Id)).Data.(*model.PostList).Posts[o2.Id]
+	o3a := &model.Post{}
+	*o3a = *ro3
+	o3a.Message = ro3.Message + "WWWWWWW"
+	if result := <-store.Post().Update(o3a, ro3); result.Err != nil {
+		t.Fatal(result.Err)
+	}
+
+	ro3a := (<-store.Post().Get(o3.Id)).Data.(*model.PostList).Posts[o3.Id]
 
-	if ro4.Message != msg2 {
+	if ro3a.Message != o3a.Message && ro3a.Hashtags != o3a.Hashtags {
 		t.Fatal("Failed to update/get")
 	}
 
-	ro5 := (<-store.Post().Get(o3.Id)).Data.(*model.PostList).Posts[o3.Id]
+	o4 := Must(store.Post().Save(&model.Post{
+		ChannelId: model.NewId(),
+		UserId:    model.NewId(),
+		Message:   model.NewId(),
+		Filenames: []string{"test"},
+	})).(*model.Post)
 
-	if ro5.Message != msg3 && ro5.Hashtags != "#hashtag" {
-		t.Fatal("Failed to update/get")
+	ro4 := (<-store.Post().Get(o4.Id)).Data.(*model.PostList).Posts[o4.Id]
+
+	o4a := &model.Post{}
+	*o4a = *ro4
+	o4a.Filenames = []string{}
+	o4a.FileIds = []string{model.NewId()}
+	if result := <-store.Post().Update(o4a, ro4); result.Err != nil {
+		t.Fatal(result.Err)
 	}
 
+	if ro4a := Must(store.Post().Get(o4.Id)).(*model.PostList).Posts[o4.Id]; len(ro4a.Filenames) != 0 {
+		t.Fatal("Failed to clear Filenames")
+	} else if len(ro4a.FileIds) != 1 {
+		t.Fatal("Failed to set FileIds")
+	}
 }
 
 func TestPostStoreDelete(t *testing.T) {
diff --git a/store/sql_store.go b/store/sql_store.go
index 4185bb705..a2bc8f1b8 100644
--- a/store/sql_store.go
+++ b/store/sql_store.go
@@ -81,6 +81,7 @@ type SqlStore struct {
 	recovery      PasswordRecoveryStore
 	emoji         EmojiStore
 	status        StatusStore
+	fileInfo      FileInfoStore
 	SchemaVersion string
 }
 
@@ -129,6 +130,7 @@ func NewSqlStore() Store {
 	sqlStore.recovery = NewSqlPasswordRecoveryStore(sqlStore)
 	sqlStore.emoji = NewSqlEmojiStore(sqlStore)
 	sqlStore.status = NewSqlStatusStore(sqlStore)
+	sqlStore.fileInfo = NewSqlFileInfoStore(sqlStore)
 
 	err := sqlStore.master.CreateTablesIfNotExists()
 	if err != nil {
@@ -155,6 +157,7 @@ func NewSqlStore() Store {
 	sqlStore.recovery.(*SqlPasswordRecoveryStore).CreateIndexesIfNotExists()
 	sqlStore.emoji.(*SqlEmojiStore).CreateIndexesIfNotExists()
 	sqlStore.status.(*SqlStatusStore).CreateIndexesIfNotExists()
+	sqlStore.fileInfo.(*SqlFileInfoStore).CreateIndexesIfNotExists()
 
 	sqlStore.preference.(*SqlPreferenceStore).DeleteUnusedFeatures()
 
@@ -643,6 +646,10 @@ func (ss SqlStore) Status() StatusStore {
 	return ss.status
 }
 
+func (ss SqlStore) FileInfo() FileInfoStore {
+	return ss.fileInfo
+}
+
 func (ss SqlStore) DropAllTables() {
 	ss.master.TruncateTables()
 }
diff --git a/store/sql_upgrade.go b/store/sql_upgrade.go
index 0029df8d4..7ee7ea199 100644
--- a/store/sql_upgrade.go
+++ b/store/sql_upgrade.go
@@ -181,7 +181,6 @@ func UpgradeDatabaseToVersion33(sqlStore *SqlStore) {
 
 func UpgradeDatabaseToVersion34(sqlStore *SqlStore) {
 	if shouldPerformUpgrade(sqlStore, VERSION_3_3_0, VERSION_3_4_0) {
-
 		sqlStore.CreateColumnIfNotExists("Status", "Manual", "BOOLEAN", "BOOLEAN", "0")
 		sqlStore.CreateColumnIfNotExists("Status", "ActiveChannel", "varchar(26)", "varchar(26)", "")
 
@@ -199,6 +198,9 @@ func UpgradeDatabaseToVersion35(sqlStore *SqlStore) {
 	sqlStore.GetMaster().Exec("UPDATE ChannelMembers SET Roles = 'channel_user' WHERE Roles = ''")
 	sqlStore.GetMaster().Exec("UPDATE ChannelMembers SET Roles = 'channel_user channel_admin' WHERE Roles = 'admin'")
 
+	// The rest of the migration from Filenames -> FileIds is done lazily in api.GetFileInfosForPost
+	sqlStore.CreateColumnIfNotExists("Posts", "FileIds", "varchar(150)", "varchar(150)", "[]")
+
 	// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 	// UNCOMMENT WHEN WE DO RELEASE
 	// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
diff --git a/store/store.go b/store/store.go
index fbe415986..c01b6d8bc 100644
--- a/store/store.go
+++ b/store/store.go
@@ -45,6 +45,7 @@ type Store interface {
 	PasswordRecovery() PasswordRecoveryStore
 	Emoji() EmojiStore
 	Status() StatusStore
+	FileInfo() FileInfoStore
 	MarkSystemRanUnitTests()
 	Close()
 	DropAllTables()
@@ -86,11 +87,13 @@ type ChannelStore interface {
 	GetMoreChannels(teamId string, userId string) StoreChannel
 	GetChannelCounts(teamId string, userId string) StoreChannel
 	GetAll(teamId string) StoreChannel
+	GetForPost(postId string) StoreChannel
 
 	SaveMember(member *model.ChannelMember) StoreChannel
 	UpdateMember(member *model.ChannelMember) StoreChannel
 	GetMembers(channelId string) StoreChannel
 	GetMember(channelId string, userId string) StoreChannel
+	GetMemberForPost(postId string, userId string) StoreChannel
 	GetMemberCount(channelId string) StoreChannel
 	RemoveMember(channelId string, userId string) StoreChannel
 	PermanentDeleteMembersByUser(userId string) StoreChannel
@@ -104,7 +107,7 @@ type ChannelStore interface {
 
 type PostStore interface {
 	Save(post *model.Post) StoreChannel
-	Update(post *model.Post, newMessage string, newHashtags string) StoreChannel
+	Update(newPost *model.Post, oldPost *model.Post) StoreChannel
 	Get(id string) StoreChannel
 	Delete(postId string, time int64) StoreChannel
 	PermanentDeleteByUser(userId string) StoreChannel
@@ -277,3 +280,12 @@ type StatusStore interface {
 	GetTotalActiveUsersCount() StoreChannel
 	UpdateLastActivityAt(userId string, lastActivityAt int64) StoreChannel
 }
+
+type FileInfoStore interface {
+	Save(info *model.FileInfo) StoreChannel
+	Get(id string) StoreChannel
+	GetByPath(path string) StoreChannel
+	GetForPost(postId string) StoreChannel
+	AttachToPost(fileId string, postId string) StoreChannel
+	DeleteForPost(postId string) StoreChannel
+}