cmake: speed up zstd detection

Before this patch we detected the presence of a specific zstd API to
see if we can use the library. zstd published that API in its first
stable release: v1.0.0 (2016-08-31).

Replace that method by detecting the zstd library version instead and
accepting if it's v1.0.0 or newer. Also display this detected version
and display a warning if the zstd found is unfit for curl.

We use the same version detection method as zstd itself, via its public
C header.

This deviates from autotools which keeps using the slow method of
looking for the API by building a test program. The outcome is the same
as long as zstd keeps offering this API.

Ref: https://github.com/facebook/zstd/commit/5a0c8e24395079f8e8cdc90aa1659cd5ab1b7427 (2016-08-12, committed)
Ref: https://github.com/facebook/zstd/releases/tag/v0.8.1 (2016-08-18, first released)
Ref: https://github.com/facebook/zstd/releases/tag/v1.0.0

Reviewed-by: Daniel Stenberg
Closes #12200

diff --git a/CMake/FindZstd.cmake b/CMake/FindZstd.cmake
index 973e6ad4a90e2340676cd6828e4e726dd92762b8..0ea9e0c871966639b1bcdd33decd0be21709992d 100644 (file)
--- a/CMake/FindZstd.cmake
+++ b/CMake/FindZstd.cmake
@@ -56,11 +56,18 @@ find_library(Zstd_LIBRARY NAMES zstd
     ${PC_Zstd_LIBRARY_DIRS}
 )
 
+if(Zstd_INCLUDE_DIR)
+  file(READ "${Zstd_INCLUDE_DIR}/zstd.h" _zstd_header)
+  string(REGEX MATCH ".*define ZSTD_VERSION_MAJOR *([0-9]+).*define ZSTD_VERSION_MINOR *([0-9]+).*define ZSTD_VERSION_RELEASE *([0-9]+)" _zstd_ver "${_zstd_header}")
+  set(Zstd_VERSION "${CMAKE_MATCH_1}.${CMAKE_MATCH_2}.${CMAKE_MATCH_3}")
+endif()
+
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(Zstd
   REQUIRED_VARS
     Zstd_LIBRARY
     Zstd_INCLUDE_DIR
+  VERSION_VAR Zstd_VERSION
 )
 
 if(Zstd_FOUND)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 75fac44f5674bbe583b283d8d315247611824164..6f2cf36ffd330460d9e5e897109b5ce61fac81b1 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -54,7 +54,6 @@
 #   HAVE_GNUTLS_SRP: `gnutls_srp_verifier` present in GnuTLS
 #   HAVE_SSL_CTX_SET_QUIC_METHOD: `SSL_CTX_set_quic_method` present in OpenSSL/wolfSSL
 #   HAVE_QUICHE_CONN_SET_QLOG_FD: `quiche_conn_set_qlog_fd` present in QUICHE
-#   HAVE_ZSTD_CREATEDSTREAM: `ZSTD_createDStream` present in Zstd
 #
 # For each of the above variables, if the variable is DEFINED (either
 # to ON or OFF), the symbol detection will be skipped.  If the
@@ -610,17 +609,12 @@ option(CURL_ZSTD "Set to ON to enable building curl with zstd support." OFF)
 set(HAVE_ZSTD OFF)
 if(CURL_ZSTD)
   find_package(Zstd REQUIRED)
-  if(NOT DEFINED HAVE_ZSTD_CREATEDSTREAM)
-    cmake_push_check_state()
-    set(CMAKE_REQUIRED_INCLUDES ${Zstd_INCLUDE_DIRS})
-    set(CMAKE_REQUIRED_LIBRARIES ${Zstd_LIBRARIES})
-    check_symbol_exists(ZSTD_createDStream "zstd.h" HAVE_ZSTD_CREATEDSTREAM)
-    cmake_pop_check_state()
-  endif()
-  if(Zstd_FOUND AND HAVE_ZSTD_CREATEDSTREAM)
+  if(Zstd_FOUND AND NOT Zstd_VERSION VERSION_LESS "1.0.0")
     set(HAVE_ZSTD ON)
     list(APPEND CURL_LIBS ${Zstd_LIBRARIES})
     include_directories(${Zstd_INCLUDE_DIRS})
+  else()
+    message(WARNING "zstd v1.0.0 or newer is required, disabling zstd support.")
   endif()
 endif()