From e43cf081f1a681e5538b55499cb42be881df51fe Mon Sep 17 00:00:00 2001
From: Leonid Yuriev <leo@yuriev.ru>
Date: Sat, 13 Mar 2021 17:05:43 +0300
Subject: [PATCH] mdbx: fix `mdbx_env_info_ex()` for a non-open environment
 case.

Fix the https://github.com/erthink/libmdbx/issues/171.

Change-Id: Iad3d0186ef40dfd40fad1c3ae0dd97f9c1161c16
---
 ChangeLog.md |  1 +
 src/core.c   | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/ChangeLog.md b/ChangeLog.md
index 42ef1931..afe05d4f 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -34,6 +34,7 @@ Fixes:
  - Fixed performance regression due non-optimal C11 atomics usage (https://github.com/erthink/libmdbx/issues/160).
  - Fixed "reincarnation" of subDB after it deletion (https://github.com/erthink/libmdbx/issues/168).
  - Fixed (disallowing) implicit subDB deletion via operations on `@MAIN`'s DBI-handle.
+ - Fixed a crash of `mdbx_env_info_ex()` in case of a call for a non-open environment (https://github.com/erthink/libmdbx/issues/171).
 
 
 ## v0.9.3 at 2021-02-02
diff --git a/src/core.c b/src/core.c
index 530bc0f5..0eab66a3 100644
--- a/src/core.c
+++ b/src/core.c
@@ -18444,6 +18444,31 @@ __cold int mdbx_env_info_ex(const MDBX_env *env, const MDBX_txn *txn,
   if (unlikely(bytes != sizeof(MDBX_envinfo)) && bytes != size_before_bootid)
     return MDBX_EINVAL;
 
+  /* is the environment open? (https://github.com/erthink/libmdbx/issues/171) */
+  if (unlikely(!env->me_map)) {
+    /* environment not yet opened */
+#if 1
+    /* default behavior: returns the available info but zeroed the rest */
+    memset(arg, 0, bytes);
+    arg->mi_geo.lower = env->me_dbgeo.lower;
+    arg->mi_geo.upper = env->me_dbgeo.upper;
+    arg->mi_geo.shrink = env->me_dbgeo.shrink;
+    arg->mi_geo.grow = env->me_dbgeo.grow;
+    arg->mi_geo.current = env->me_dbgeo.now;
+    arg->mi_maxreaders = env->me_maxreaders;
+    arg->mi_dxb_pagesize = env->me_psize;
+    arg->mi_sys_pagesize = env->me_os_psize;
+    if (likely(bytes > size_before_bootid)) {
+      arg->mi_bootid.current.x = bootid.x;
+      arg->mi_bootid.current.y = bootid.y;
+    }
+    return MDBX_SUCCESS;
+#else
+    /* some users may prefer this behavior: return appropriate error */
+    return MDBX_EPERM;
+#endif
+  }
+
   const MDBX_meta *const meta0 = METAPAGE(env, 0);
   const MDBX_meta *const meta1 = METAPAGE(env, 1);
   const MDBX_meta *const meta2 = METAPAGE(env, 2);