package/leveldb: fix detection of the snappy library

Pull a patch pending in an upstream pull request to fix the detection
of the snappy library when we are in static linking configurations.

Fixes:

  https://bugs.busybox.net/show_bug.cgi?id=12671

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/leveldb/0004-cmake-Use-find_package-to-find-Snappy.patch

@@ -0,0 +1,98 @@
+From 450c1d88b3e1af34614294830b4dc0612d198d26 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <chfast@gmail.com>
+Date: Wed, 8 May 2019 10:42:03 +0200
+Subject: [PATCH] cmake: Use find_package() to find Snappy
+
+Upstream: https://github.com/google/leveldb/pull/686/commits/3e73a396a082efc76e065ae974fe18c3bb27219d
+[Thomas: this commit allows to fix the detection of the snappy library
+in static link configurations]
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
+---
+ CMakeLists.txt         | 12 ++++++++----
+ cmake/FindSnappy.cmake | 31 +++++++++++++++++++++++++++++++
+ 2 files changed, 39 insertions(+), 4 deletions(-)
+ create mode 100644 cmake/FindSnappy.cmake
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 78fead6..2efccda 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -6,6 +6,9 @@ cmake_minimum_required(VERSION 3.9)
+ # Keep the version below in sync with the one in db.h
+ project(leveldb VERSION 1.22.0 LANGUAGES C CXX)
+ 
++# Include local CMake modules.
++list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
++
+ # This project can use C11, but will gracefully decay down to C89.
+ set(CMAKE_C_STANDARD 11)
+ set(CMAKE_C_STANDARD_REQUIRED OFF)
+@@ -31,13 +34,14 @@ option(LEVELDB_INSTALL "Install LevelDB's header and library" ON)
+ include(TestBigEndian)
+ test_big_endian(LEVELDB_IS_BIG_ENDIAN)
+ 
++find_package(Snappy)
++
+ include(CheckIncludeFile)
+ check_include_file("unistd.h" HAVE_UNISTD_H)
+ 
+ include(CheckLibraryExists)
+ check_library_exists(atomic __atomic_fetch_add_4 "" HAVE_ATOMIC)
+ check_library_exists(crc32c crc32c_value "" HAVE_CRC32C)
+-check_library_exists(snappy snappy_compress "" HAVE_SNAPPY)
+ check_library_exists(tcmalloc malloc "" HAVE_TCMALLOC)
+ 
+ include(CheckCXXSymbolExists)
+@@ -276,9 +280,9 @@ endif(HAVE_ATOMIC)
+ if(HAVE_CRC32C)
+   target_link_libraries(leveldb crc32c)
+ endif(HAVE_CRC32C)
+-if(HAVE_SNAPPY)
+-  target_link_libraries(leveldb snappy)
+-endif(HAVE_SNAPPY)
++if(TARGET Snappy::snappy)
++  target_link_libraries(leveldb Snappy::snappy)
++endif()
+ if(HAVE_TCMALLOC)
+   target_link_libraries(leveldb tcmalloc)
+ endif(HAVE_TCMALLOC)
+diff --git a/cmake/FindSnappy.cmake b/cmake/FindSnappy.cmake
+new file mode 100644
+index 0000000..88c1de9
+--- /dev/null
++++ b/cmake/FindSnappy.cmake
+@@ -0,0 +1,31 @@
++# Copyright 2019 The LevelDB Authors. All rights reserved.
++# Use of this source code is governed by a BSD-style license that can be
++# found in the LICENSE file. See the AUTHORS file for names of contributors.
++
++find_library(SNAPPY_LIBRARY
++    NAMES snappy
++    HINTS ${SNAPPY_ROOT_DIR}/lib
++)
++
++find_path(SNAPPY_INCLUDE_DIR
++    NAMES snappy.h
++    HINTS ${SNAPPY_ROOT_DIR}/include
++)
++
++include(FindPackageHandleStandardArgs)
++find_package_handle_standard_args(Snappy DEFAULT_MSG SNAPPY_LIBRARY SNAPPY_INCLUDE_DIR)
++
++mark_as_advanced(SNAPPY_LIBRARY SNAPPY_INCLUDE_DIR)
++
++if(SNAPPY_FOUND)
++  set(HAVE_SNAPPY TRUE) # For compatibity with generating port_config.h.
++
++  # Add imported targets.
++  # Follow the package naming convetion 'Snappy::' from
++  # https://github.com/google/snappy/blob/master/CMakeLists.txt#L211.
++  add_library(Snappy::snappy UNKNOWN IMPORTED)
++  set_target_properties(Snappy::snappy PROPERTIES
++      IMPORTED_LOCATION ${SNAPPY_LIBRARY}
++      INTERFACE_INCLUDE_DIRECTORIES ${SNAPPY_INCLUDE_DIR}
++  )
++endif()
+-- 
+2.26.2
+