Support `yadm.cygwin-copy` configuration (#62)

With `yadm.cygwin-copy` set to "true", alternate files will be copies
instead of symlinks, but only when running on Cygwin.

test/115_accept_introspect.bats

@@ -73,7 +73,7 @@ function count_introspect() {
         Exit with 0
   "
 
-  count_introspect "configs" 0 11 'yadm\.auto-alt'
+  count_introspect "configs" 0 12 'yadm\.auto-alt'
 }
 
 @test "Command 'introspect' (repo)" {

test/116_accept_cygwin_copy.bats

@@ -0,0 +1,102 @@
+load common
+load_fixtures
+
+IN_REPO=(alt*)
+export TEST_TREE_WITH_CYGWIN=1
+export SIMULATED_CYGWIN="CYGWIN_NT-6.1-WOW64"
+
+setup() {
+  destroy_tmp
+  build_repo "${IN_REPO[@]}"
+}
+
+test_alt() {
+  local cygwin_copy="$1"
+  local is_cygwin="$2"
+  local expect_link="$3"
+
+  case "$cygwin_copy" in
+    true|false)
+      git config --file="$T_YADM_CONFIG" "yadm.cygwin-copy" "$cygwin_copy"
+      ;;
+  esac
+
+  if [ "$is_cygwin" = "true" ]; then
+    echo '#!/bin/sh' > "$T_TMP/uname"
+    echo "echo $SIMULATED_CYGWIN" >> "$T_TMP/uname"
+    chmod a+x "$T_TMP/uname"
+  fi
+
+  local expected_content
+  expected_content="$T_DIR_WORK/alt-test##$(PATH="$T_TMP:$PATH" uname -s)"
+
+  PATH="$T_TMP:$PATH" run "${T_YADM_Y[@]}" alt
+
+  if [ -L "$T_DIR_WORK/alt-test" ] && [ "$expect_link" != 'true' ] ; then
+    echo "ERROR: Alt should be a simple file, but isn't"
+    return 1
+  fi
+  if [ ! -L "$T_DIR_WORK/alt-test" ] && [ "$expect_link" = 'true' ] ; then
+    echo "ERROR: Alt should use symlink, but doesn't"
+    return 1
+  fi
+
+  if ! diff "$T_DIR_WORK/alt-test" "$expected_content"; then
+    echo "ERROR: Alt contains different data than expected"
+    return 1
+  fi
+}
+
+@test "Option 'yadm.cygwin-copy' (unset, non-cygwin)" {
+  echo "
+    When the option 'yadm.cygwin-copy' is unset
+    and the OS is not CYGWIN
+    Verify alternate is a symlink
+  "
+  test_alt 'unset' 'false' 'true'
+}
+
+@test "Option 'yadm.cygwin-copy' (true, non-cygwin)" {
+  echo "
+    When the option 'yadm.cygwin-copy' is true
+    and the OS is not CYGWIN
+    Verify alternate is a symlink
+  "
+  test_alt 'true' 'false' 'true'
+}
+
+@test "Option 'yadm.cygwin-copy' (false, non-cygwin)" {
+  echo "
+    When the option 'yadm.cygwin-copy' is false
+    and the OS is not CYGWIN
+    Verify alternate is a symlink
+  "
+  test_alt 'false' 'false' 'true'
+}
+
+@test "Option 'yadm.cygwin-copy' (unset, cygwin)" {
+  echo "
+    When the option 'yadm.cygwin-copy' is unset
+    and the OS is CYGWIN
+    Verify alternate is a symlink
+  "
+  test_alt 'unset' 'true' 'true'
+}
+
+@test "Option 'yadm.cygwin-copy' (true, cygwin)" {
+  echo "
+    When the option 'yadm.cygwin-copy' is true
+    and the OS is CYGWIN
+    Verify alternate is a copy
+  "
+  test_alt 'true' 'true' 'false'
+}
+
+@test "Option 'yadm.cygwin-copy' (false, cygwin)" {
+  echo "
+    When the option 'yadm.cygwin-copy' is false
+    and the OS is CYGWIN
+    Verify alternate is a symlink
+  "
+  test_alt 'false' 'true' 'true'
+}

test/common.bash

@@ -205,6 +205,18 @@ function create_worktree() {
     echo "{{ YADM_CLASS }}-{{ YADM_OS }}-{{ YADM_HOSTNAME }}-{{ YADM_USER }}" > "$DIR_WORKTREE/alt-jinja##yadm.j2"
   fi
 
+  #; for some cygwin tests
+  if [ ! -z "$TEST_TREE_WITH_CYGWIN" ] ; then
+    for f in                        \
+      "alt-test##"                  \
+      "alt-test##$T_SYS"            \
+      "alt-test##$SIMULATED_CYGWIN" \
+    ;
+    do
+      make_parents "$DIR_WORKTREE/$f"
+      echo "$f" > "$DIR_WORKTREE/$f"
+    done
+  fi
 
   if [ ! -z "$TEST_TREE_WITH_WILD" ] ; then
     #; wildcard test data - yes this is a big mess :(

yadm

@@ -175,6 +175,14 @@ function alt() {
     done < "$YADM_ENCRYPT"
   fi
 
+  #; decide if a copy should be done instead of a symbolic link
+  local do_copy=0
+  if [[ $OPERATING_SYSTEM == CYGWIN* ]] ; then
+    if [[ $(config --bool yadm.cygwin-copy) == "true" ]] ; then
+      do_copy=1
+    fi
+  fi
+
   #; loop over all "tracked" files
   #; for every file which matches the above regex, create a symlink
   for match in $match1 $match2; do
@@ -190,7 +198,11 @@ function alt() {
               new_link="${BASH_REMATCH[1]}"
               debug "Linking $alt_path to $new_link"
               [ -n "$loud" ] && echo "Linking $alt_path to $new_link"
-              ln -nfs "$alt_path" "$new_link"
+              if [ "$do_copy" -eq 1 ]; then
+                cp -f "$alt_path" "$new_link"
+              else
+                ln -nfs "$alt_path" "$new_link"
+              fi
               last_linked="$alt_path"
             fi
           fi
@@ -586,6 +598,7 @@ local.os
 local.user
 yadm.auto-alt
 yadm.auto-perms
+yadm.cygwin-copy
 yadm.git-program
 yadm.gpg-perms
 yadm.gpg-program

yadm.1

@@ -376,6 +376,11 @@ By default, the first "gpg" found in $PATH is used.
 .B yadm.git-program
 Specify an alternate program to use instead of "git".
 By default, the first "git" found in $PATH is used.
+.TP
+.B yadm.cygwin-copy
+If set to "true", for Cygwin hosts, alternate files will be copies instead of
+symbolic links. This might be desirable, because non-Cygwin software may not
+properly interpret Cygwin symlinks.
 
 .RE
 These last four "local" configurations are not stored in the