From a2e2e5c8a0e3e4ffb25d8177b4af115e06d02925 Mon Sep 17 00:00:00 2001
From: Leonid Yuriev <leo@yuriev.ru>
Date: Sun, 20 Sep 2020 20:49:53 +0300
Subject: [PATCH] mdbx: allow sendfile() and copy_file_range() to fail for
 Valgrind/QEMU cases.

Change-Id: I37ee8d652d91a8d2106c782beceaacb13e9f667f
---
 src/core.c    | 32 +++++++++++++++++++-------------
 src/options.h |  8 ++++----
 2 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/src/core.c b/src/core.c
index f20b3091..e6fbd52e 100644
--- a/src/core.c
+++ b/src/core.c
@@ -16315,30 +16315,36 @@ static int __cold mdbx_env_copy_asis(MDBX_env *env, MDBX_txn *read_txn,
       buffer + ceil_powerof2(meta_bytes, env->me_os_psize);
   for (size_t offset = meta_bytes; rc == MDBX_SUCCESS && offset < used_size;) {
 #if MDBX_USE_SENDFILE
-    if (dest_is_pipe) {
+    static bool sendfile_unavailable;
+    if (dest_is_pipe && likely(!sendfile_unavailable)) {
       off_t in_offset = offset;
-      const intptr_t written =
+      const ssize_t written =
           sendfile(fd, env->me_lazy_fd, &in_offset, used_size - offset);
-      if (unlikely(written <= 0)) {
-        rc = written ? errno : MDBX_ENODATA;
-        break;
+      if (likely(written > 0)) {
+        offset = in_offset;
+        continue;
       }
-      offset = in_offset;
-      continue;
+      rc = MDBX_ENODATA;
+      if (written == 0 || ignore_enosys(rc = errno) != MDBX_RESULT_TRUE)
+        break;
+      sendfile_unavailable = true;
     }
 #endif /* MDBX_USE_SENDFILE */
 
 #if MDBX_USE_COPYFILERANGE
-    if (!dest_is_pipe) {
+    static bool copyfilerange_unavailable;
+    if (!dest_is_pipe && likely(!copyfilerange_unavailable)) {
       off_t in_offset = offset, out_offset = offset;
       ssize_t bytes_copied = copy_file_range(
           env->me_lazy_fd, &in_offset, fd, &out_offset, used_size - offset, 0);
-      if (unlikely(bytes_copied <= 0)) {
-        rc = bytes_copied ? errno : MDBX_ENODATA;
-        break;
+      if (likely(bytes_copied > 0)) {
+        offset = in_offset;
+        continue;
       }
-      offset = in_offset;
-      continue;
+      rc = MDBX_ENODATA;
+      if (bytes_copied == 0 || ignore_enosys(rc = errno) != MDBX_RESULT_TRUE)
+        break;
+      copyfilerange_unavailable = true;
     }
 #endif /* MDBX_USE_COPYFILERANGE */
 
diff --git a/src/options.h b/src/options.h
index 2f0d2f65..0191ecc6 100644
--- a/src/options.h
+++ b/src/options.h
@@ -164,9 +164,9 @@
 
 /** Advanced: Using sendfile() syscall (autodetection by default). */
 #ifndef MDBX_USE_SENDFILE
-#if (defined(__linux__) || defined(__gnu_linux__)) &&                          \
-    (!defined(__ANDROID_API__) || __ANDROID_API__ >= 21) &&                    \
-    !defined(MDBX_SAFE4QEMU)
+#if ((defined(__linux__) || defined(__gnu_linux__)) &&                         \
+     __GLIBC_PREREQ(2, 3)) ||                                                  \
+    (defined(__ANDROID_API__) && __ANDROID_API__ >= 21)
 #define MDBX_USE_SENDFILE 1
 #else
 #define MDBX_USE_SENDFILE 0
@@ -175,7 +175,7 @@
 
 /** Advanced: Using copy_file_range() syscall (autodetection by default). */
 #ifndef MDBX_USE_COPYFILERANGE
-#if __GLIBC_PREREQ(2, 27) && defined(_GNU_SOURCE) && !defined(MDBX_SAFE4QEMU)
+#if __GLIBC_PREREQ(2, 27) && defined(_GNU_SOURCE)
 #define MDBX_USE_COPYFILERANGE 1
 #else
 #define MDBX_USE_COPYFILERANGE 0