2 files changed, 21 insertions, 18 deletions

diff --git a/model/post.go b/model/post.go
index 4a774b5d4..ae0627a03 100644
--- a/model/post.go
+++ b/model/post.go
@@ -40,7 +40,9 @@ const (
 	POST_FILEIDS_MAX_RUNES      = 150
 	POST_FILENAMES_MAX_RUNES    = 4000
 	POST_HASHTAGS_MAX_RUNES     = 1000
-	POST_MESSAGE_MAX_RUNES      = 4000
+	POST_MESSAGE_MAX_RUNES_V1   = 4000
+	POST_MESSAGE_MAX_BYTES_V2   = 65535                         // Maximum size of a TEXT column in MySQL
+	POST_MESSAGE_MAX_RUNES_V2   = POST_MESSAGE_MAX_BYTES_V2 / 4 // Assume a worst-case representation
 	POST_PROPS_MAX_RUNES        = 8000
 	POST_PROPS_MAX_USER_RUNES   = POST_PROPS_MAX_RUNES - 400 // Leave some room for system / pre-save modifications
 	POST_CUSTOM_TYPE_PREFIX     = "custom_"
@@ -141,7 +143,7 @@ func (o *Post) Etag() string {
 	return Etag(o.Id, o.UpdateAt)
 }
 
-func (o *Post) IsValid() *AppError {
+func (o *Post) IsValid(maxPostSize int) *AppError {
 
 	if len(o.Id) != 26 {
 		return NewAppError("Post.IsValid", "model.post.is_valid.id.app_error", nil, "", http.StatusBadRequest)
@@ -179,7 +181,7 @@ func (o *Post) IsValid() *AppError {
 		return NewAppError("Post.IsValid", "model.post.is_valid.original_id.app_error", nil, "", http.StatusBadRequest)
 	}
 
-	if utf8.RuneCountInString(o.Message) > POST_MESSAGE_MAX_RUNES {
+	if utf8.RuneCountInString(o.Message) > maxPostSize {
 		return NewAppError("Post.IsValid", "model.post.is_valid.msg.app_error", nil, "id="+o.Id, http.StatusBadRequest)
 	}
 
diff --git a/model/post_test.go b/model/post_test.go
index 5d5e7c9ec..af350d76e 100644
--- a/model/post_test.go
+++ b/model/post_test.go
@@ -23,72 +23,73 @@ func TestPostJson(t *testing.T) {
 
 func TestPostIsValid(t *testing.T) {
 	o := Post{}
+	maxPostSize := 10000
 
-	if err := o.IsValid(); err == nil {
+	if err := o.IsValid(maxPostSize); err == nil {
 		t.Fatal("should be invalid")
 	}
 
 	o.Id = NewId()
-	if err := o.IsValid(); err == nil {
+	if err := o.IsValid(maxPostSize); err == nil {
 		t.Fatal("should be invalid")
 	}
 
 	o.CreateAt = GetMillis()
-	if err := o.IsValid(); err == nil {
+	if err := o.IsValid(maxPostSize); err == nil {
 		t.Fatal("should be invalid")
 	}
 
 	o.UpdateAt = GetMillis()
-	if err := o.IsValid(); err == nil {
+	if err := o.IsValid(maxPostSize); err == nil {
 		t.Fatal("should be invalid")
 	}
 
 	o.UserId = NewId()
-	if err := o.IsValid(); err == nil {
+	if err := o.IsValid(maxPostSize); err == nil {
 		t.Fatal("should be invalid")
 	}
 
 	o.ChannelId = NewId()
 	o.RootId = "123"
-	if err := o.IsValid(); err == nil {
+	if err := o.IsValid(maxPostSize); err == nil {
 		t.Fatal("should be invalid")
 	}
 
 	o.RootId = ""
 	o.ParentId = "123"
-	if err := o.IsValid(); err == nil {
+	if err := o.IsValid(maxPostSize); err == nil {
 		t.Fatal("should be invalid")
 	}
 
 	o.ParentId = NewId()
 	o.RootId = ""
-	if err := o.IsValid(); err == nil {
+	if err := o.IsValid(maxPostSize); err == nil {
 		t.Fatal("should be invalid")
 	}
 
 	o.ParentId = ""
-	o.Message = strings.Repeat("0", 4001)
-	if err := o.IsValid(); err == nil {
+	o.Message = strings.Repeat("0", maxPostSize+1)
+	if err := o.IsValid(maxPostSize); err == nil {
 		t.Fatal("should be invalid")
 	}
 
-	o.Message = strings.Repeat("0", 4000)
-	if err := o.IsValid(); err != nil {
+	o.Message = strings.Repeat("0", maxPostSize)
+	if err := o.IsValid(maxPostSize); err != nil {
 		t.Fatal(err)
 	}
 
 	o.Message = "test"
-	if err := o.IsValid(); err != nil {
+	if err := o.IsValid(maxPostSize); err != nil {
 		t.Fatal(err)
 	}
 
 	o.Type = "junk"
-	if err := o.IsValid(); err == nil {
+	if err := o.IsValid(maxPostSize); err == nil {
 		t.Fatal("should be invalid")
 	}
 
 	o.Type = POST_CUSTOM_TYPE_PREFIX + "type"
-	if err := o.IsValid(); err != nil {
+	if err := o.IsValid(maxPostSize); err != nil {
 		t.Fatal(err)
 	}
 }