[feature] Fetch + display custom emoji in statuses from remote instances (#807)

* start implementing remote emoji fetcher

* update status where pk

* aaa

* tidy up a little

* check size limits for emojis

* thank you linter, i love you <3

* update swagger docs

* add emoji dereference test

* make emoji max sizes configurable

* normalize db.ErrAlreadyExists

1 files changed, 9 insertions, 1 deletions

diff --git a/internal/api/client/admin/emojicreate.go b/internal/api/client/admin/emojicreate.go
index 39ebd5adf..eef49b2c7 100644
--- a/internal/api/client/admin/emojicreate.go
+++ b/internal/api/client/admin/emojicreate.go
@@ -26,6 +26,7 @@ import (
 	"github.com/gin-gonic/gin"
 	"github.com/superseriousbusiness/gotosocial/internal/api"
 	"github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 	"github.com/superseriousbusiness/gotosocial/internal/validate"
@@ -56,7 +57,9 @@ import (
 //   required: true
 // - name: image
 //   in: formData
-//   description: A png or gif image of the emoji. Animated pngs work too!
+//   description: |-
+//     A png or gif image of the emoji. Animated pngs work too!
+//     To ensure compatibility with other fedi implementations, emoji size limit is 50kb by default.
 //   type: file
 //   required: true
 //
@@ -126,5 +129,10 @@ func validateCreateEmoji(form *model.EmojiCreateRequest) error {
 		return errors.New("no emoji given")
 	}
 
+	maxSize := config.GetMediaEmojiLocalMaxSize()
+	if form.Image.Size > int64(maxSize) {
+		return fmt.Errorf("emoji image too large: image is %dKB but size limit for custom emojis is %dKB", form.Image.Size/1024, maxSize/1024)
+	}
+
 	return validate.EmojiShortcode(form.Shortcode)
 }