libssh2

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# Copyright (C) Alexander Lamaison <alexander.lamaison@gmail.com>
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#
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# Redistribution and use in source and binary forms,
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# with or without modification, are permitted provided
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# that the following conditions are met:
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#
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#   Redistributions of source code must retain the above
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#   copyright notice, this list of conditions and the
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#   following disclaimer.
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#
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#   Redistributions in binary form must reproduce the above
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#   copyright notice, this list of conditions and the following
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#   disclaimer in the documentation and/or other materials
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#   provided with the distribution.
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#
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#   Neither the name of the copyright holder nor the names
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#   of any other contributors may be used to endorse or
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#   promote products derived from this software without
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#   specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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# CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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# INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
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# USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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# OF SUCH DAMAGE.
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#
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# SPDX-License-Identifier: BSD-3-Clause
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# - check_function_exists_maybe_need_library(<function> <var> [lib1 ... libn])
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#
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# Check if function is available for linking, first without extra libraries, and
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# then, if not found that way, linking in each optional library as well.  This
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# function is similar to autotools AC_SEARCH_LIBS.
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#
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# If the function if found, this will define <var>.
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#
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# If the function was only found by linking in an additional library, this
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# will define NEED_LIB_LIBX, where LIBX is the one of lib1 to libn that
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# makes the function available, in uppercase.
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#
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# The following variables may be set before calling this macro to
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# modify the way the check is run:
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#
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#  CMAKE_REQUIRED_FLAGS = string of compile command line flags
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#  CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar)
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#  CMAKE_REQUIRED_INCLUDES = list of include directories
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#  CMAKE_REQUIRED_LIBRARIES = list of libraries to link
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#
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include(CheckFunctionExists)
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include(CheckLibraryExists)
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function(check_function_exists_may_need_library function variable)
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  check_function_exists(${function} ${variable})
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  if(NOT ${variable})
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    foreach(lib IN LISTS ARGN)
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      string(TOUPPER ${lib} UP_LIB)
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      # Use new variable to prevent cache from previous step shortcircuiting
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      # new test
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      check_library_exists(${lib} ${function} "" HAVE_${function}_IN_${lib})
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      if(HAVE_${function}_IN_${lib})
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        set(${variable} 1 CACHE INTERNAL
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          "Function ${function} found in library ${lib}")
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        set(NEED_LIB_${UP_LIB} 1 CACHE INTERNAL
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          "Need to link ${lib}")
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        break()
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      endif()
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    endforeach()
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  endif()
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endfunction()
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