fix: ensure installed binaries have executable permissions

src/fpm/installer.f90

@@ -9,7 +9,7 @@ module fpm_installer
   use fpm_error, only : error_t, fatal_error
   use fpm_targets, only: build_target_t, FPM_TARGET_ARCHIVE, FPM_TARGET_SHARED, FPM_TARGET_NAME
   use fpm_filesystem, only : join_path, mkdir, exists, unix_path, windows_path, get_local_prefix, &
-      basename
+       basename, set_executable
 
   implicit none
   private
@@ -210,11 +210,13 @@ subroutine install_executable(self, executable, error)
     call self%install(executable, self%bindir, error)
     if (allocated(error)) return
 
+    ! Set executable permissions on the installed file
+    exe_path = join_path(self%install_destination(self%bindir), basename(executable))
+    call set_executable(exe_path)
+
     ! on MacOS, add two relative paths for search of dynamic library dependencies: 
     add_rpath: if (self%os==OS_MACOS) then  
 
-        exe_path = join_path(self%install_destination(self%bindir) , basename(executable))
-
         ! First path: for bin/lib/include structure
         cmd = "install_name_tool -add_rpath @executable_path/../lib " // exe_path
         call self%run(cmd, error)

src/fpm_filesystem.F90

@@ -16,7 +16,8 @@ module fpm_filesystem
     public :: basename, canon_path, dirname, is_dir, join_path, number_of_rows, list_files, get_local_prefix, &
             mkdir, exists, get_temp_filename, windows_path, unix_path, getline, delete_file, fileopen, fileclose, &
             filewrite, warnwrite, parent_dir, is_hidden_file, read_lines, read_lines_expanded, which, run, &
-            os_delete_dir, is_absolute_path, get_home, execute_and_read_output, get_dos_path
+            os_delete_dir, is_absolute_path, get_home, execute_and_read_output, get_dos_path, &
+           set_executable
 
 #ifndef FPM_BOOTSTRAP
     interface
@@ -26,6 +27,13 @@ function c_opendir(dir) result(r) bind(c, name="c_opendir")
             type(c_ptr) :: r
         end function c_opendir
 
+        function c_chmod(path, mode) result(r) bind(c, name="chmod")
+            import c_char, c_int
+            character(kind=c_char), intent(in) :: path(*)
+            integer(kind=c_int), value :: mode
+            integer(kind=c_int) :: r
+        end function c_chmod
+
         function c_readdir(dir) result(r) bind(c, name="c_readdir")
             import c_ptr
             type(c_ptr), intent(in), value :: dir
@@ -1254,4 +1262,28 @@ function get_dos_path(path,error)
 
     end function get_dos_path
 
+    !> Set executable permissions (chmod +x on Unix, no-op on Windows)
+    subroutine set_executable(filename)
+        character(len=*), intent(in) :: filename
+        integer :: stat
+
+        if (.not. os_is_unix()) return
+
+#ifndef FPM_BOOTSTRAP
+        ! Use C library chmod (faster, standard)
+        ! o'755' is octal for rwxr-xr-x
+        stat = c_chmod(filename // c_null_char, int(o'755', c_int))
+        if (stat /= 0) then
+            write(stderr, *) "Warning: Failed to set executable permissions on: ", filename
+        end if
+#else
+        ! Fallback using shell command
+        call run("chmod +x " // filename, echo=.false., verbose=.false., exitstat=stat)
+        if (stat /= 0) then
+            write(stderr, *) "Warning: Failed to set executable permissions on: ", filename
+        end if
+#endif
+
+    end subroutine set_executable
+
 end module fpm_filesystem

test/fpm_test/test_filesystem.f90

@@ -2,7 +2,8 @@ module test_filesystem
     use testsuite, only: new_unittest, unittest_t, error_t, test_failed
     use fpm_filesystem, only: canon_path, is_dir, mkdir, os_delete_dir, &
                               join_path, is_absolute_path, get_home, &
-                              delete_file, read_lines, get_temp_filename
+                              delete_file, read_lines, get_temp_filename, &
+                              set_executable, filewrite, exists
     use fpm_environment, only: OS_WINDOWS, get_os_type, os_is_unix
     use fpm_strings, only: string_t, split_lines_first_last
     implicit none
@@ -24,7 +25,8 @@ subroutine collect_filesystem(tests)
             & new_unittest("test-is-absolute-path", test_is_absolute_path), &
             & new_unittest("test-get-home", test_get_home), &
             & new_unittest("test-split-lines-first-last", test_split_lines_first_last), &
-            & new_unittest("test-crlf-lines", test_dir_with_crlf) &
+            & new_unittest("test-crlf-lines", test_dir_with_crlf), &
+            & new_unittest("test-set-executable", test_set_executable) &
             ]
 
     end subroutine collect_filesystem
@@ -428,6 +430,41 @@ subroutine test_dir_with_crlf(error)
         1 format("Failed reading file with CRLF: ",a,:,i0,:,a,:,i0)
 
     end subroutine test_dir_with_crlf
+
+    ! Test for set_executable
+    subroutine test_set_executable(error)
+        type(error_t), allocatable, intent(out) :: error
+        character(len=:), allocatable :: temp_file
+        integer :: stat
+
+        ! 1. Setup: Create a dummy file
+        temp_file = "test_exec_perm.txt"
+        call filewrite(temp_file, [character(len=13) :: "dummy content"])
+
+        if (.not. exists(temp_file)) then
+             call test_failed(error, "Setup failed: Could not create temp file")
+             return
+        end if
+
+        ! 2. Action: Call the function
+        call set_executable(temp_file)
+
+        ! 3. Assertion: Verify permissions
+        if (os_is_unix()) then
+            ! 'test -x' returns 0 if executable, 1 if not
+           call execute_command_line("test -x " // temp_file, exitstat=stat)
+
+            if (stat /= 0) then
+                call test_failed(error, "Test Failed: File was not made executable on Unix")
+                ! Attempt cleanup before returning
+                call delete_file(temp_file)
+                return
+            end if
+        end if
+
+        call delete_file(temp_file)
+
+    end subroutine test_set_executable
 
 
 end module test_filesystem