From fcc6d3359033a1fb2bdf38d63eb8881c80595606 Mon Sep 17 00:00:00 2001 From: Mariell Hoversholm Date: Sun, 1 Nov 2020 16:43:31 +0100 Subject: [PATCH] Throw proper exception on empty JsonList file Related to #4174, #4717. As it stands, `JsonList` throws an NPE on `jsonarray.iterator()` when the reader given is at EOF. This means there is an unintelligible message shown to the player: ``` [16:44:31 ERROR]: Encountered an unexpected exception java.lang.NullPointerException: Cannot invoke "com.google.gson.JsonArray.iterator()" because "jsonarray" is null at net.minecraft.server.v1_16_R2.JsonList.load(JsonList.java:192) ~[patched_1.16.3.jar:git-Paper-248] at net.minecraft.server.v1_16_R2.DedicatedPlayerList.y(SourceFile:95) ~[patched_1.16.3.jar:git-Paper-248] ... ``` This is clearly not understandable to the untrained eye: what is `jsonarray`? What is `DedicatedPlayerList.y`? This rather does a proper exception message: ``` [16:42:59 ERROR]: Encountered an unexpected exception java.lang.NullPointerException: The file "banned-players.json" is either empty or corrupt at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:787) ~[paper-1.16.3.jar:git-Paper-"8e6d90c2d"] at net.minecraft.server.v1_16_R2.JsonList.load(JsonList.java:190) ~[paper-1.16.3.jar:git-Paper-"8e6d90c2d"] at net.minecraft.server.v1_16_R2.DedicatedPlayerList.y(SourceFile:95) ~[paper-1.16.3.jar:git-Paper-"8e6d90c2d"] ... ``` It is still an exception, which server owners may or may not understand, but the message now says exactly what went wrong, and who would've known, now we know what `DedicatedPlayerList.y` is, and we know what file was broken. This is more of a quality of life change, but it is certainly useful to the server owners that come into `#paper-help` and the issue tracker (#4174) to ask for help with unintelligible messages we need to open a patched Paper project to make any sense out of. Check state of jsonarray instead of checkNotNull Co-authored-by: Riley Park --- ...oper-exception-on-empty-JsonList-file.patch | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) create mode 100644 Spigot-Server-Patches/0683-Throw-proper-exception-on-empty-JsonList-file.patch diff --git a/Spigot-Server-Patches/0683-Throw-proper-exception-on-empty-JsonList-file.patch b/Spigot-Server-Patches/0683-Throw-proper-exception-on-empty-JsonList-file.patch new file mode 100644 index 0000000000..d5890e49a7 --- /dev/null +++ b/Spigot-Server-Patches/0683-Throw-proper-exception-on-empty-JsonList-file.patch @@ -0,0 +1,18 @@ +From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 +From: Mariell Hoversholm +Date: Sun, 1 Nov 2020 16:43:11 +0100 +Subject: [PATCH] Throw proper exception on empty JsonList file + + +diff --git a/src/main/java/net/minecraft/server/JsonList.java b/src/main/java/net/minecraft/server/JsonList.java +index 1fc0139cb9694ddea41f57d95774c3b47e8530c5..8da5f976109accc84b26ec4045776aa8a9799f3d 100644 +--- a/src/main/java/net/minecraft/server/JsonList.java ++++ b/src/main/java/net/minecraft/server/JsonList.java +@@ -187,6 +187,7 @@ public abstract class JsonList> { + + try { + JsonArray jsonarray = (JsonArray) JsonList.b.fromJson(bufferedreader, JsonArray.class); ++ com.google.common.base.Preconditions.checkState(jsonarray != null, "The file \"" + this.c.getName() + "\" is either empty or corrupt"); // Paper + + this.d.clear(); + Iterator iterator = jsonarray.iterator();