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# Forked from Gromacs

# - Define macro to check large file support
#
#  myx_cmake_test_large_files(VARIABLE)
#
#  VARIABLE will be set to true if off_t is 64 bits, and fseeko/ftello present.
#  This macro will also set defines necessary enable large file support, for instance
#  _LARGE_FILES
#  _LARGEFILE_SOURCE
#  _FILE_OFFSET_BITS 64
#  HAVE_FSEEKO
#  HAVE__FSEEKI64
#
#  However, it is YOUR job to make sure these defines are set in a cmakedefine so they
#  end up in a config.h file that is included in your source if necessary!

include_guard(GLOBAL)
include(CheckTypeSize)


set(_test_file_offset_bits_c
"
#include <sys/types.h>
#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
int off_t_is_large[ (LARGE_OFF_T % 2147483629 == 721 && LARGE_OFF_T % 2147483647 == 1) ? 1 : -1 ];
int main(int argc, char **argv) { return 0; }
")
set(_test_file_offset_bits_c_path ${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/test_file_offset_bits.c)
file(WRITE ${_test_file_offset_bits_c_path} ${_test_file_offset_bits_c})


set(_test_large_file_c_in
"
#cmakedefine _LARGEFILE_SOURCE
#cmakedefine _LARGEFILE64_SOURCE
#cmakedefine _LARGE_FILES
#cmakedefine _FILE_OFFSET_BITS @_FILE_OFFSET_BITS@

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>

#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))

int main(int argc, char **argv)
{
  int off_t_is_large[ (LARGE_OFF_T % 2147483629 == 721 && LARGE_OFF_T % 2147483647 == 1) ? 1 : -1 ];
  FILE *fp = fopen(argv[0],\"r\");
  off_t offset = ftello( fp );
  fseeko( fp, offset, SEEK_CUR );
  fclose(fp);
  return off_t_is_large[0] || argc;
}
")
set(_test_large_file_c_path ${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/test_large_file.c)
set(_test_large_file_c_in_path ${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/test_large_file.c.in)
file(WRITE ${_test_large_file_c_in_path} ${_test_large_file_c_in})


set(_test_windows_fseek_c
"
#include <stdio.h>
int main()
{
  __int64 off=0;
  _fseeki64(NULL, off, SEEK_SET);
  return 0;
}
")
set(_test_windows_fseek_c_path ${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/test_windows_fseek.c)
file(WRITE ${_test_windows_fseek_c_path} ${_test_windows_fseek_c})


macro(myx_cmake_test_large_files VARIABLE)
  if(NOT DEFINED ${VARIABLE})

    # On most platforms it is probably overkill to first test the flags for 64-bit off_t,
    # and then separately fseeko. However, in the future we might have 128-bit filesystems
    # (ZFS), so it might be dangerous to indiscriminately set e.g. _FILE_OFFSET_BITS=64.

    message(STATUS "Checking for 64-bit off_t")

    # First check without any special flags
    try_compile(FILE64_OK ${CMAKE_CURRENT_BINARY_DIR} ${_test_file_offset_bits_c_path})
    if(FILE64_OK)
      message(STATUS "Checking for 64-bit off_t - present")
    endif()

    if(NOT FILE64_OK)
      # Test with _FILE_OFFSET_BITS=64
      try_compile(FILE64_OK ${CMAKE_CURRENT_BINARY_DIR} ${_test_file_offset_bits_c_path}
                  COMPILE_DEFINITIONS "-D_FILE_OFFSET_BITS=64")
      if(FILE64_OK)
        message(STATUS "Checking for 64-bit off_t - present with _FILE_OFFSET_BITS=64")
        set(_FILE_OFFSET_BITS 64 CACHE INTERNAL "64-bit off_t requires _FILE_OFFSET_BITS=64")
      endif()
    endif()

    if(NOT FILE64_OK)
      # Test with _LARGE_FILES
      try_compile(FILE64_OK ${CMAKE_CURRENT_BINARY_DIR} ${_test_file_offset_bits_c_path}
                  COMPILE_DEFINITIONS "-D_LARGE_FILES")
      if(FILE64_OK)
        message(STATUS "Checking for 64-bit off_t - present with _LARGE_FILES")
        set(_LARGE_FILES 1 CACHE INTERNAL "64-bit off_t requires _LARGE_FILES")
      endif()
    endif()

    if(NOT FILE64_OK)
      # Test with _LARGEFILE_SOURCE
      try_compile(FILE64_OK ${CMAKE_CURRENT_BINARY_DIR} ${_test_file_offset_bits_c_path}
                  COMPILE_DEFINITIONS "-D_LARGEFILE_SOURCE")
      if(FILE64_OK)
        message(STATUS "Checking for 64-bit off_t - present with _LARGEFILE_SOURCE")
        set(_LARGEFILE_SOURCE 1 CACHE INTERNAL "64-bit off_t requires _LARGEFILE_SOURCE")
      endif()
    endif()

    if(NOT FILE64_OK)
      message(STATUS "Checking for 64-bit off_t - not present")
    else()
      # 64-bit off_t found. Now check that ftello/fseeko is available.

      # Set the flags we might have determined to be required above
      configure_file(${_test_large_file_c_in_path} ${_test_large_file_c_path})

      message(STATUS "Checking for fseeko/ftello")
      # Test if ftello/fseeko are available
      try_compile(FSEEKO_COMPILE_OK ${CMAKE_CURRENT_BINARY_DIR} ${_test_large_file_c_path})
      if(FSEEKO_COMPILE_OK)
        message(STATUS "Checking for fseeko/ftello - present")
      endif()

      if(NOT FSEEKO_COMPILE_OK)
        # glibc 2.2 neds _LARGEFILE_SOURCE for fseeko (but not 64-bit off_t...)
        try_compile(FSEEKO_COMPILE_OK ${CMAKE_CURRENT_BINARY_DIR} ${_test_large_file_c_path}
                    COMPILE_DEFINITIONS "-D_LARGEFILE_SOURCE")
        if(FSEEKO_COMPILE_OK)
          message(STATUS "Checking for fseeko/ftello - present with _LARGEFILE_SOURCE")
          set(_LARGEFILE_SOURCE 1 CACHE INTERNAL "64-bit fseeko requires _LARGEFILE_SOURCE")
        else()
          set(FILE64_OK 0)
          message(STATUS "64-bit off_t present but fseeko/ftello not found!")
        endif()
      endif()
    endif()

    # cmake-lint: disable=C0103
    if(NOT FILE64_OK)
      # now check for Windows stuff
      try_compile(FILE64_OK ${CMAKE_CURRENT_BINARY_DIR} ${_test_windows_fseek_c_path})
      if(FILE64_OK)
        message(STATUS "Checking for 64-bit off_t - present with _fseeki64")
        set(HAVE__FSEEKI64 1 CACHE INTERNAL "64-bit off_t requires _fseeki64")
      endif()
    endif()

    if(FSEEKO_COMPILE_OK)
      set(${VARIABLE} 1 CACHE INTERNAL "Result of test for large file support" FORCE)
      set(HAVE_FSEEKO 1 CACHE INTERNAL "64-bit fseeko is available" FORCE)
    elseif(HAVE__FSEEKI64)
      set(${VARIABLE} 1 CACHE INTERNAL "Result of test for large file support" FORCE)
      set(HAVE__FSEEKI64 1 CACHE INTERNAL "Windows 64-bit fseek" FORCE)
    else()
      check_type_size("long int" SIZEOF_LONG_INT)
      if(SIZEOF_LONG_INT EQUAL 8) #standard fseek is OK for 64bit
        set(${VARIABLE} 1 CACHE INTERNAL "Result of test for large file support" FORCE)
      else()
        message(FATAL_ERROR "Checking for 64-bit file support failed.")
      endif()
    endif()
  endif()
endmacro(myx_cmake_test_large_files VARIABLE)