Re: [Tarantool-patches] [tarantool-patches] Re: [PATCH] build: fix OpenSSL linking problems on FreeBSD

Re: [Tarantool-patches] [tarantool-patches] Re: [PATCH] build: fix OpenSSL linking problems on FreeBSD

[Alexander Turenko]

Thanks for reviews!

CCed Kirill.

WBR, Alexander Turenko.

On Fri, Oct 18, 2019 at 05:30:05AM +0300, Alexander Tikhonov wrote:
> The path seems right and LGTM from my side.
> 
> 
> >Четверг, 17 октября 2019, 14:57 +03:00 от Igor Munkin <imun@tarantool.org>:
> >
> >Sasha,
> >
> >Thanks, the wording is great and the whole patch LGTM.
> >
> >As discussed offline I've created a new follow-up ticket #4575.
> >
> >On 17.10.19, Alexander Turenko wrote:
> >> I fixed all known flaws now: see inline answers and the whole new patch
> >> at end of the email.
> >> 
> >> WBR, Alexander Turenko.
> >> 
> >> On Tue, Sep 24, 2019 at 04:15:56PM +0300, Igor Munkin wrote:
> >> > Sasha,
> >> > 
> >> > Thanks, see no flaws except for the issue with Apple CommandLineTools
> >> > compiler on OSX Mojave you're working on. Please consider a sole minor
> >> > comment below.
> >> 
> >> Fixed it by passing -isysroot=<SDK_PATH> via CPPFLAGS (PP is a
> >> preprocessor) and CFLAGS.
> >> 
> >> Added the following paragraph to the commit message:
> >> 
> >>  | When CC is passed to libcurl's configure script, the new problem opens
> >>  | on Mac OS. CMake chooses XCode toolchain by default (at least on a
> >>  | particular system where I tried it), which requires -isysroot=<SDK_PATH>
> >>  | option to be passed to a preprocessor and a compiler in order to find
> >>  | system headers. See [2] for more information.
> >>  |
> >>  | <...>
> >>  |
> >>  | [2]:  https://developer.apple.com/documentation/xcode_release_notes/xcode_10_release_notes#3035623
> >> 
> >> > 
> >> > On 23.09.19, Alexander Turenko wrote:
> >> > > FreeBSD has OpenSSL as part of the base system: libraries are located in
> >> > > /usr/lib, headers are in /usr/include. However a user may install the
> >> > > library into /usr/local/{lib,include} from ports / pkg. In this case
> >> > > tarantool did choose /usr/local version, while libcurl will pick up a
> >> > > base system library. This is fixed by passing --with-ssl option with an
> >> > > argument (/usr/local or /usr if custom -DOPENSSL_ROOT_DIR=<...> is not
> >> > > passed).
> >> > > 
> >> > > Now the behaviour is the following. If -DOPENSSL_ROOT_DIR=<...> is
> >> > > passed, then try to use OpenSSL from it. Otherwise find the library in
> >> > > /usr/local and then in /usr. This is right as for tarantool's crypto
> >> > > module as well as for libcurl submodule.
> >> > > 
> >> > > There is a flaw here: a user is unable to choose a base system library
> >> > > if a ports / pkg version of OpenSSL is installed. The reason here is
> >> > > that tarantool's crypto module depends on other libraries and
> >> > > -I/usr/local/include may be added to build options. I have no good
> >> > > solution for that, so `cmake . -DOPENSSL_ROOT_DIR=/usr` will give a
> >> > > warning on FreeBSD and `gmake` likely will fail if libraries are of
> >> > > different versions (see cmake/os.cmake comments for more information).
> >> > > See also a [discussion][1] in FreeBSD community about all those /usr and
> >> > > /usr/local problems.
> >> > > 
> >> > > There were two other problems that may fail tarantool build on FreeBSD:
> >> > > they are fixed in this commit and described below.
> >> > > 
> >> > > First, libcurl's configure script chooses GCC by default if it exists
> >> > > (say, installed from ports / pkg). It is unexpected behaviour when
> >> > > tarantool sources itself are built with clang. Now it is fixed by
> >> > > passing a compiler explicitly to the libcurl's configure script: the
> >> > > library will use base system clang by default or one that a user pass to
> >> > > tarantool's cmake.
> >> > > 
> >> > > Side note: GCC has /usr/local/include in its default headers search
> >> > > paths; libcurl's configure script chooses GCC as a compiler and OpenSSL
> >> > > from a base system by default that leads to OpenSSL header / library
> >> > > mismatch. It is the primary reason of the build fail that was fixed in
> >> > > 1f2338bd809585b0b38fe07fd9f80c31747374c2 ('build: FreeBSD packages
> >> > > installation'). It is not much relevant anymore, because we don't try to
> >> > > link with a base system OpenSSL if /usr/local one exists (if it is asked
> >> > > explicitly with -DOPENSSL_ROOT_DIR=<...> we'll do, but will give a
> >> > > warning). Anyway, it is important to know such details if we'll change
> >> > > build scripts in a future.
> >> 
> >> Added a note in parentheses:
> >> 
> >>  | Side note: GCC has /usr/local/include in its default headers search
> >>  | paths; libcurl's configure script chooses GCC as a compiler and OpenSSL
> >>  | from a base system by default (when CC and --with-ssl=<...> are not set)
> >>  | <...>
> >> 
> >> > > 
> >> > > Second, backtraces are not supported on FreeBSD, but were enabled if
> >> > > libunwind headers is found. This leads to an error on cmake stage,
> >> > > because of unability to find a right library (this is the bug). Now we
> >> > > disable backtraces on FreeBSD by default even if libunwind is found. See
> >> > > #4278 for more information.
> >> > > 
> >> > > [1]:  https://wiki.freebsd.org/WarnerLosh/UsrLocal
> >> > > 
> >> > > Follows up #4490.
> >> > > ---
> >> > > 
> >> > >  https://github.com/tarantool/tarantool/issues/4490
> >> > >  https://github.com/tarantool/tarantool/commits/Totktonada/gh-4490-fix-freebsd-openssl-linking-problems-full-ci
> >> > > 
> >> > > This is more request for review of wording rather then of the code: hope
> >> > > I verified it carefully enough.
> >> > > 
> >> > >  cmake/BuildLibCURL.cmake | 15 +++++++--------
> >> > >  cmake/compiler.cmake     |  4 +++-
> >> > >  cmake/os.cmake           | 27 +++++++++++++++++++++++++++
> >> > >  3 files changed, 37 insertions(+), 9 deletions(-)
> >> > > 
> >> > > diff --git a/cmake/BuildLibCURL.cmake b/cmake/BuildLibCURL.cmake
> >> > > index 866b3c49e..45f5af23e 100644
> >> > > --- a/cmake/BuildLibCURL.cmake
> >> > > +++ b/cmake/BuildLibCURL.cmake
> >> > > @@ -14,14 +14,10 @@ macro(curl_build)
> >> > >          message(FATAL_ERROR "Unable to find zlib")
> >> > >      endif()
> >> > > 
> >> > > -    # Set curl option to find OpenSSL library.
> >> > > -    if ("${OPENSSL_ROOT_DIR}" STREQUAL "")
> >> > > -        # Linux / FreeBSD.
> >> > > -        set(LIBCURL_OPENSSL_OPT "--with-ssl")
> >> > > -    else()
> >> > > -        # Mac OS.
> >> > > -        set(LIBCURL_OPENSSL_OPT "--with-ssl=${OPENSSL_ROOT_DIR}")
> >> > > -    endif()
> >> > > +    # Use the same OpenSSL library for libcurl as is used for
> >> > > +    # tarantool itself.
> >> > > +    get_filename_component(FOUND_OPENSSL_ROOT_DIR ${OPENSSL_INCLUDE_DIR} DIRECTORY)
> >> > > +    set(LIBCURL_OPENSSL_OPT "--with-ssl=${FOUND_OPENSSL_ROOT_DIR}")
> >> > > 
> >> > >      include(ExternalProject)
> >> > >      ExternalProject_Add(
> >> > > @@ -35,6 +31,8 @@ macro(curl_build)
> >> > >          CONFIGURE_COMMAND
> >> > >              cd <SOURCE_DIR> && ./buildconf &&
> >> > >              cd <BINARY_DIR> && <SOURCE_DIR>/configure
> >> > > +                CC=${CMAKE_C_COMPILER}
> >> > > +                CXX=${CMAKE_CXX_COMPILER}
> >> > 
> >> > This changeset breaks build for OSX Mojave. The note is left as a
> >> > reminder of known problem to be fixed in a while.
> >> 
> >> Yep, fixed (see CPPFLAGS and CFLAGS in the new patch).
> >> 
> >> > 
> >> > >                  --prefix <INSTALL_DIR>
> >> > >                  --enable-static
> >> > >                  --enable-shared
> >> > > @@ -112,6 +110,7 @@ macro(curl_build)
> >> > >          set(CURL_LIBRARIES ${CURL_LIBRARIES} rt)
> >> > >      endif()
> >> > > 
> >> > > +    unset(FOUND_OPENSSL_ROOT_DIR)
> >> > >      unset(LIBCURL_INSTALL_DIR)
> >> > >      unset(LIBCURL_BINARY_DIR)
> >> > >      unset(LIBCURL_SOURCE_DIR)
> >> > > diff --git a/cmake/compiler.cmake b/cmake/compiler.cmake
> >> > > index 887485c80..c9ad2b092 100644
> >> > > --- a/cmake/compiler.cmake
> >> > > +++ b/cmake/compiler.cmake
> >> > > @@ -128,8 +128,10 @@ else()
> >> > >  endif()
> >> > >  find_library(UNWIND_LIBRARY PATH_SUFFIXES system NAMES ${UNWIND_LIB_NAME})
> >> > > 
> >> > > +# Disabled backtraces support on FreeBSD by default, because of
> >> > > +# gh-4278.
> >> > >  set(ENABLE_BACKTRACE_DEFAULT OFF)
> >> > > -if (UNWIND_LIBRARY AND HAVE_LIBUNWIND_H)
> >> > > +if (NOT TARGET_OS_FREEBSD AND UNWIND_LIBRARY AND HAVE_LIBUNWIND_H)
> >> > >      set(ENABLE_BACKTRACE_DEFAULT ON)
> >> > >  endif()
> >> > > 
> >> > > diff --git a/cmake/os.cmake b/cmake/os.cmake
> >> > > index ea581108b..fe96ce773 100644
> >> > > --- a/cmake/os.cmake
> >> > > +++ b/cmake/os.cmake
> >> > > @@ -22,6 +22,33 @@ elseif (${CMAKE_SYSTEM_NAME} STREQUAL "kFreeBSD")
> >> > >  elseif (${CMAKE_SYSTEM_NAME} STREQUAL "FreeBSD")
> >> > >      set(TARGET_OS_FREEBSD 1)
> >> > >      find_package_message(PLATFORM "Building for FreeBSD" "${CMAKE_SYSTEM_NAME}")
> >> > > +
> >> > > +    # FreeBSD has OpenSSL library installed in /usr as part of a
> >> > > +    # base system. A user may install OpenSSL from ports / pkg to
> >> > > +    # /usr/local. It is tricky to use the library from /usr in the
> >> > > +    # case, because a compilation unit can also depend on
> >> > > +    # libraries from /usr/local. When -I/usr/local/include is
> >> > > +    # passed to a compiler it will find openssl/ssl.h from
> >> > > +    # /usr/local/include first.
> >> > > +    #
> >> > > +    # In theory we can create a directory on the build stage and
> >> > > +    # fill it with symlinks to choosen headers. However this way
> >> > > +    # does not look as usual way to pick libraries to build
> >> > > +    # against. I suspect that this is common problem on FreeBSD
> >> > > +    # and we should wait for some general resolution from FreeBSD
> >> > > +    # developers rather then work it around.
> >> > > +    #
> >> > > +    # Verify that /usr is not set as a directory to pick OpenSSL
> >> > > +    # library and header files, because it is likely that a user
> >> > > +    # set it to use the library from a base system, while the
> >> > > +    # library is also installed into /usr/local.
> >> > > +    get_filename_component(REAL_OPENSSL_ROOT_DIR "${OPENSSL_ROOT_DIR}"
> >> > > +                           REALPATH BASE_DIR "${CMAKE_BINARY_DIR}")
> >> > > +    if ("${REAL_OPENSSL_ROOT_DIR}" STREQUAL "/usr")
> >> > 
> >> > It would be much clearer if you dropped a few words for the warning
> >> > level usage instead of fatal one here (I guess I saw the rationale
> >> > within a commit message).
> >> 
> >> Added the following paragraph:
> >> 
> >>  | It is possible however that a user is aware of the problem,
> >>  | but want to use -DOPENSSL_ROOT_DIR=<...> CMake option to
> >>  | choose OpenSSL from /usr anyway. We should not fail the
> >>  | build and block this ability. Say, a user may know that
> >>  | there are no OpenSSL libraries in /usr/local, but finds it
> >>  | convenient to set the CMake option explicitly due to some
> >>  | external reason.
> >> 
> >> > 
> >> > > +        message(WARNING "Using OPENSSL_ROOT_DIR on FreeBSD to choose base "
> >> > > +                        "system libraries is not supported")
> >> > > +    endif()
> >> > > +    unset(REAL_OPENSSL_ROOT_DIR)
> >> > >  elseif (${CMAKE_SYSTEM_NAME} STREQUAL "NetBSD")
> >> > >      set(TARGET_OS_NETBSD 1)
> >> > >      find_package_message(PLATFORM "Building for NetBSD" "${CMAKE_SYSTEM_NAME}")
> >> > > -- 
> >> > > 2.22.0
> >> > > 
> >> > 
> >> > -- 
> >> > Best regards,
> >> > IM
> >> 
> >> ----
> >> 
> >> build: fix OpenSSL linking problems on FreeBSD
> >> 
> >> FreeBSD has OpenSSL as part of the base system: libraries are located in
> >> /usr/lib, headers are in /usr/include. However a user may install the
> >> library into /usr/local/{lib,include} from ports / pkg. In this case
> >> tarantool did choose /usr/local version, while libcurl will pick up a
> >> base system library. This is fixed by passing --with-ssl option with an
> >> argument (/usr/local or /usr if custom -DOPENSSL_ROOT_DIR=<...> is not
> >> passed).
> >> 
> >> Now the behaviour is the following. If -DOPENSSL_ROOT_DIR=<...> is
> >> passed, then try to use OpenSSL from it. Otherwise find the library in
> >> /usr/local and then in /usr. This is right as for tarantool's crypto
> >> module as well as for libcurl submodule.
> >> 
> >> There is a flaw here: a user is unable to choose a base system library
> >> if a ports / pkg version of OpenSSL is installed. The reason here is
> >> that tarantool's crypto module depends on other libraries and
> >> -I/usr/local/include may be added to build options. I have no good
> >> solution for that, so `cmake . -DOPENSSL_ROOT_DIR=/usr` will give a
> >> warning on FreeBSD and `gmake` likely will fail if libraries are of
> >> different versions (see cmake/os.cmake comments for more information).
> >> See also a [discussion][1] in FreeBSD community about all those /usr and
> >> /usr/local problems.
> >> 
> >> There were two other problems that may fail tarantool build on FreeBSD:
> >> they are fixed in this commit and described below.
> >> 
> >> First, libcurl's configure script chooses GCC by default if it exists
> >> (say, installed from ports / pkg). It is unexpected behaviour when
> >> tarantool sources itself are built with clang. Now it is fixed by
> >> passing a compiler explicitly to the libcurl's configure script: the
> >> library will use base system clang by default or one that a user pass to
> >> tarantool's cmake.
> >> 
> >> Side note: GCC has /usr/local/include in its default headers search
> >> paths; libcurl's configure script chooses GCC as a compiler and OpenSSL
> >> from a base system by default (when CC and --with-ssl=<...> are not set)
> >> that leads to OpenSSL header / library mismatch. It is the primary
> >> reason of the build fail that was fixed in
> >> 1f2338bd809585b0b38fe07fd9f80c31747374c2 ('build: FreeBSD packages
> >> installation'). It is not much relevant anymore, because we don't try to
> >> link with a base system OpenSSL if /usr/local one exists (however if it
> >> is asked explicitly with -DOPENSSL_ROOT_DIR=<...> we'll do, but will
> >> give a warning). Anyway, it is important to know such details if we'll
> >> change build scripts in a future.
> >> 
> >> Second, backtraces are not supported on FreeBSD, but were enabled if
> >> libunwind headers is found. This leads to an error on cmake stage,
> >> because of inability to find a right library (this is a bug). Now we
> >> disable backtraces on FreeBSD by default even if libunwind is found. See
> >> #4278 for more information.
> >> 
> >> When CC is passed to libcurl's configure script, the new problem opens
> >> on Mac OS. CMake chooses XCode toolchain by default (at least on a
> >> particular system where I tried it), which requires -isysroot=<SDK_PATH>
> >> option to be passed to a preprocessor and a compiler in order to find
> >> system headers. See [2] for more information.
> >> 
> >> [1]:  https://wiki.freebsd.org/WarnerLosh/UsrLocal
> >> [2]:  https://developer.apple.com/documentation/xcode_release_notes/xcode_10_release_notes#3035623
> >> 
> >> Follows up #4490.
> >> ---
> >>  cmake/BuildLibCURL.cmake | 25 ++++++++++++++++++-------
> >>  cmake/compiler.cmake     |  4 +++-
> >>  cmake/os.cmake           | 35 +++++++++++++++++++++++++++++++++++
> >>  3 files changed, 56 insertions(+), 8 deletions(-)
> >> 
> >> diff --git a/cmake/BuildLibCURL.cmake b/cmake/BuildLibCURL.cmake
> >> index 866b3c49e..0dc7676d6 100644
> >> --- a/cmake/BuildLibCURL.cmake
> >> +++ b/cmake/BuildLibCURL.cmake
> >> @@ -14,13 +14,18 @@ macro(curl_build)
> >>          message(FATAL_ERROR "Unable to find zlib")
> >>      endif()
> >> 
> >> -    # Set curl option to find OpenSSL library.
> >> -    if ("${OPENSSL_ROOT_DIR}" STREQUAL "")
> >> -        # Linux / FreeBSD.
> >> -        set(LIBCURL_OPENSSL_OPT "--with-ssl")
> >> -    else()
> >> -        # Mac OS.
> >> -        set(LIBCURL_OPENSSL_OPT "--with-ssl=${OPENSSL_ROOT_DIR}")
> >> +    # Use the same OpenSSL library for libcurl as is used for
> >> +    # tarantool itself.
> >> +    get_filename_component(FOUND_OPENSSL_ROOT_DIR ${OPENSSL_INCLUDE_DIR} DIRECTORY)
> >> +    set(LIBCURL_OPENSSL_OPT "--with-ssl=${FOUND_OPENSSL_ROOT_DIR}")
> >> +
> >> +    # Pass -isysroot=<SDK_PATH> option on Mac OS to a preprocessor
> >> +    # and a C compiler to find header files installed with an SDK.
> >> +    set(LIBCURL_CPPFLAGS "")
> >> +    set(LIBCURL_CFLAGS "")
> >> +    if (TARGET_OS_DARWIN AND NOT "${CMAKE_OSX_SYSROOT}" STREQUAL "")
> >> +        set(LIBCURL_CPPFLAGS "${LIBCURL_CPPFLAGS} ${CMAKE_C_SYSROOT_FLAG} ${CMAKE_OSX_SYSROOT}")
> >> +        set(LIBCURL_CFLAGS "${LIBCURL_CFLAGS} ${CMAKE_C_SYSROOT_FLAG} ${CMAKE_OSX_SYSROOT}")
> >>      endif()
> >> 
> >>      include(ExternalProject)
> >> @@ -35,6 +40,9 @@ macro(curl_build)
> >>          CONFIGURE_COMMAND
> >>              cd <SOURCE_DIR> && ./buildconf &&
> >>              cd <BINARY_DIR> && <SOURCE_DIR>/configure
> >> +                CC=${CMAKE_C_COMPILER}
> >> +                CPPFLAGS=${LIBCURL_CPPFLAGS}
> >> +                CFLAGS=${LIBCURL_CFLAGS}
> >>                  --prefix <INSTALL_DIR>
> >>                  --enable-static
> >>                  --enable-shared
> >> @@ -112,6 +120,9 @@ macro(curl_build)
> >>          set(CURL_LIBRARIES ${CURL_LIBRARIES} rt)
> >>      endif()
> >> 
> >> +    unset(LIBCURL_CPPFLAGS)
> >> +    unset(LIBCURL_CFLAGS)
> >> +    unset(FOUND_OPENSSL_ROOT_DIR)
> >>      unset(LIBCURL_INSTALL_DIR)
> >>      unset(LIBCURL_BINARY_DIR)
> >>      unset(LIBCURL_SOURCE_DIR)
> >> diff --git a/cmake/compiler.cmake b/cmake/compiler.cmake
> >> index 887485c80..c9ad2b092 100644
> >> --- a/cmake/compiler.cmake
> >> +++ b/cmake/compiler.cmake
> >> @@ -128,8 +128,10 @@ else()
> >>  endif()
> >>  find_library(UNWIND_LIBRARY PATH_SUFFIXES system NAMES ${UNWIND_LIB_NAME})
> >> 
> >> +# Disabled backtraces support on FreeBSD by default, because of
> >> +# gh-4278.
> >>  set(ENABLE_BACKTRACE_DEFAULT OFF)
> >> -if (UNWIND_LIBRARY AND HAVE_LIBUNWIND_H)
> >> +if (NOT TARGET_OS_FREEBSD AND UNWIND_LIBRARY AND HAVE_LIBUNWIND_H)
> >>      set(ENABLE_BACKTRACE_DEFAULT ON)
> >>  endif()
> >> 
> >> diff --git a/cmake/os.cmake b/cmake/os.cmake
> >> index ea581108b..0ed554b9b 100644
> >> --- a/cmake/os.cmake
> >> +++ b/cmake/os.cmake
> >> @@ -22,6 +22,41 @@ elseif (${CMAKE_SYSTEM_NAME} STREQUAL "kFreeBSD")
> >>  elseif (${CMAKE_SYSTEM_NAME} STREQUAL "FreeBSD")
> >>      set(TARGET_OS_FREEBSD 1)
> >>      find_package_message(PLATFORM "Building for FreeBSD" "${CMAKE_SYSTEM_NAME}")
> >> +
> >> +    # FreeBSD has OpenSSL library installed in /usr as part of a
> >> +    # base system. A user may install OpenSSL from ports / pkg to
> >> +    # /usr/local. It is tricky to use the library from /usr in the
> >> +    # case, because a compilation unit can also depend on
> >> +    # libraries from /usr/local. When -I/usr/local/include is
> >> +    # passed to a compiler it will find openssl/ssl.h from
> >> +    # /usr/local/include first.
> >> +    #
> >> +    # In theory we can create a directory on the build stage and
> >> +    # fill it with symlinks to choosen headers. However this way
> >> +    # does not look as usual way to pick libraries to build
> >> +    # against. I suspect that this is common problem on FreeBSD
> >> +    # and we should wait for some general resolution from FreeBSD
> >> +    # developers rather then work it around.
> >> +    #
> >> +    # Verify that /usr is not set as a directory to pick OpenSSL
> >> +    # library and header files, because it is likely that a user
> >> +    # set it to use the library from a base system, while the
> >> +    # library is also installed into /usr/local.
> >> +    #
> >> +    # It is possible however that a user is aware of the problem,
> >> +    # but want to use -DOPENSSL_ROOT_DIR=<...> CMake option to
> >> +    # choose OpenSSL from /usr anyway. We should not fail the
> >> +    # build and block this ability. Say, a user may know that
> >> +    # there are no OpenSSL libraries in /usr/local, but finds it
> >> +    # convenient to set the CMake option explicitly due to some
> >> +    # external reason.
> >> +    get_filename_component(REAL_OPENSSL_ROOT_DIR "${OPENSSL_ROOT_DIR}"
> >> +                           REALPATH BASE_DIR "${CMAKE_BINARY_DIR}")
> >> +    if ("${REAL_OPENSSL_ROOT_DIR}" STREQUAL "/usr")
> >> +        message(WARNING "Using OPENSSL_ROOT_DIR on FreeBSD to choose base "
> >> +                        "system libraries is not supported")
> >> +    endif()
> >> +    unset(REAL_OPENSSL_ROOT_DIR)
> >>  elseif (${CMAKE_SYSTEM_NAME} STREQUAL "NetBSD")
> >>      set(TARGET_OS_NETBSD 1)
> >>      find_package_message(PLATFORM "Building for NetBSD" "${CMAKE_SYSTEM_NAME}")
> >
> >-- 
> >Best regards,
> >IM
> >
> 
> 
> -- 
> Alexander Tikhonov

Re: [Tarantool-patches] [tarantool-patches] Re: [PATCH] build: fix OpenSSL linking problems on FreeBSD

[Alexander Turenko]

I'll resend the patch as a patchset of two patches: it will handle the
following build problems on FreeBSD and Mac OS:

- https://github.com/tarantool/tarantool/issues/4490
  "FreeBSD compilation failing due to curl dependencies"
- https://github.com/tarantool/tarantool/issues/4587
  "build: failed to link on MacOS with GNU binutils in PATH"

I'll do one change for this patch:

> > >> +    # Pass -isysroot=<SDK_PATH> option on Mac OS to a preprocessor
> > >> +    # and a C compiler to find header files installed with an SDK.
> > >> +    set(LIBCURL_CPPFLAGS "")
> > >> +    set(LIBCURL_CFLAGS "")
> > >> +    if (TARGET_OS_DARWIN AND NOT "${CMAKE_OSX_SYSROOT}" STREQUAL "")
> > >> +        set(LIBCURL_CPPFLAGS "${LIBCURL_CPPFLAGS} ${CMAKE_C_SYSROOT_FLAG} ${CMAKE_OSX_SYSROOT}")
> > >> +        set(LIBCURL_CFLAGS "${LIBCURL_CFLAGS} ${CMAKE_C_SYSROOT_FLAG} ${CMAKE_OSX_SYSROOT}")
> > >>      endif()


Added the following paragraph here.

 | diff --git a/cmake/BuildLibCURL.cmake b/cmake/BuildLibCURL.cmake
 | index 336c14c88..12062ec8b 100644
 | --- a/cmake/BuildLibCURL.cmake
 | +++ b/cmake/BuildLibCURL.cmake
 | @@ -21,6 +21,11 @@ macro(curl_build)
 |  
 |      # Pass -isysroot=<SDK_PATH> option on Mac OS to a preprocessor
 |      # and a C compiler to find header files installed with an SDK.
 | +    #
 | +    # The idea here is to don't pass all compiler/linker options
 | +    # that is set for tarantool, but only a subset that is
 | +    # necessary for choosen toolchain, and let curl's configure
 | +    # script set options that are appropriate for libcurl.
 |      set(LIBCURL_CPPFLAGS "")
 |      set(LIBCURL_CFLAGS "")
 |      if (TARGET_OS_DARWIN AND NOT "${CMAKE_OSX_SYSROOT}" STREQUAL "")