Merge pull request #142 from certik/os

Initial implementation of get_os()

1 files changed, 56 insertions, 0 deletions

diff --git a/fpm/src/fpm.f90 b/fpm/src/fpm.f90
index 85597c0..cc5666b 100644
--- a/fpm/src/fpm.f90
+++ b/fpm/src/fpm.f90
@@ -3,10 +3,66 @@ implicit none
 private
 public :: print_help, cmd_build
 
+integer, parameter :: OS_LINUX = 1
+integer, parameter :: OS_MACOS = 2
+integer, parameter :: OS_WINDOWS = 3
+
 contains
 
+integer function get_os_type() result(r)
+! Determine the OS type
+!
+! Returns one of OS_LINUX, OS_MACOS, OS_WINDOWS.
+!
+! Currently we use the $HOME and $HOMEPATH environment variables to determine
+! the OS type. That is not 100% accurate in all cases, but it seems to be good
+! enough for now. See the following issue for a more robust solution:
+!
+! https://github.com/fortran-lang/fpm/issues/144
+!
+character(len=100) :: val
+integer stat
+! Only Windows define $HOMEPATH by default and we test its value to improve the
+! chances of it working even if a user defines $HOMEPATH on Linux or macOS.
+call get_environment_variable("HOMEPATH", val, status=stat)
+if (stat == 0 .and. val(1:7) == "\Users\") then
+    r = OS_WINDOWS
+    return
+end if
+
+! We assume that $HOME=/home/... is Linux, $HOME=/Users/... is macOS, otherwise
+! we assume Linux. This is only a heuristic and can easily fail.
+call get_environment_variable("HOME", val, status=stat)
+if (stat == 1) then
+    print *, "$HOME does not exist"
+    error stop
+end if
+if (stat /= 0) then
+    print *, "get_environment_variable() failed"
+    error stop
+end if
+if (val(1:6) == "/home/") then
+    r = OS_LINUX
+else if (val(1:7) == "/Users/") then
+    r = OS_MACOS
+else
+    ! This will happen on HPC systems that typically do not use either /home nor
+    ! /Users for $HOME. Those systems are typically Linux, so for now we simply
+    ! set Linux here.
+    r = OS_LINUX
+end if
+end function
+
 subroutine print_help()
 print *, "Fortran Package Manager (fpm)"
+select case (get_os_type())
+    case (OS_LINUX)
+        print *, "OS Type: Linux"
+    case (OS_MACOS)
+        print *, "OS Type: macOS"
+    case (OS_WINDOWS)
+        print *, "OS Type: Windows"
+end select
 end subroutine
 
 subroutine run(cmd)