From 45defdc170c2ec01a5cd6406dc91a229577f970b Mon Sep 17 00:00:00 2001
From: Leo Yuriev <leo@yuriev.ru>
Date: Wed, 21 Jun 2017 01:42:27 +0300
Subject: [PATCH] mdbx: refine err returning (MDBX_EPERM, etc).

Change-Id: Iaa21a0e6632be47d6ef2a3676ba5e1381fc03b4d
---
 src/mdbx.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/mdbx.c b/src/mdbx.c
index edd0387b..66ebd74f 100644
--- a/src/mdbx.c
+++ b/src/mdbx.c
@@ -3847,7 +3847,7 @@ fail:
 
 int __cold mdbx_env_get_maxkeysize(MDBX_env *env) {
   if (!env || env->me_signature != MDBX_ME_SIGNATURE || !env->me_maxkey_limit)
-    return MDBX_EINVAL;
+    return -MDBX_EINVAL;
   return env->me_maxkey_limit;
 }
 
@@ -4068,21 +4068,24 @@ int __cold mdbx_env_set_maxdbs(MDBX_env *env, MDBX_dbi dbs) {
     return MDBX_EBADSIGN;
 
   if (unlikely(env->me_map))
-    return MDBX_EINVAL;
+    return MDBX_EPERM;
 
   env->me_maxdbs = dbs + CORE_DBS;
   return MDBX_SUCCESS;
 }
 
 int __cold mdbx_env_set_maxreaders(MDBX_env *env, unsigned readers) {
-  if (unlikely(!env || readers < 1))
+  if (unlikely(readers < 1 || readers > INT16_MAX))
+    return MDBX_EINVAL;
+
+  if (unlikely(!env))
     return MDBX_EINVAL;
 
   if (unlikely(env->me_signature != MDBX_ME_SIGNATURE))
     return MDBX_EBADSIGN;
 
-  if (unlikely(env->me_map || readers > INT16_MAX))
-    return MDBX_EINVAL;
+  if (unlikely(env->me_map))
+    return MDBX_EPERM;
 
   env->me_maxreaders = readers;
   return MDBX_SUCCESS;