lib/portability: Add @go.native_file_path_or_url

Closes #187. Part of #186. Replaces `git_for_windows_native_path` and
updates the interface to print to a result variable rather than standard
output, avoiding a subshell when no conversion takes place.

lib/platform

@@ -1,4 +1,4 @@
-#! /bin/bash
+#! /usr/bin/env bash
 #
 # Sets the `_GO_PLATFORM_*` family of environment variables
 #

lib/portability

@@ -0,0 +1,35 @@
+#! /usr/bin/env bash
+#
+# Functions to manage platform differences
+#
+# Exports:
+#   @go.native_file_path_or_url
+#     Converts a file system path or 'file://' URL to a platform-native path
+
+. "$_GO_USE_MODULES" 'platform' 'validation'
+
+# Converts a file system path or 'file://' URL to a platform-native path
+#
+# This is useful when passing file paths or URLs to native programs on Git for
+# Windows, or validating the output of such programs, to ensure portability.
+# The resulting path will contain forward slashes.
+#
+# Prints both converted and unconverted paths and URLs to the specified result
+# variable.
+#
+# Arguments:
+#   result_var_name:  Name of caller's variable in which to store the result
+#   path:             File system path or 'file://' URL to convert
+@go.native_file_path_or_url() {
+  local _gnp_protocol="${2%%://*}"
+  @go.validate_identifier_or_die 'Result variable name' "$1"
+
+  if [[ "$_GO_PLATFORM_ID" != 'msys-git' ]] ||
+    [[ "$_gnp_protocol" != "$2" && "$_gnp_protocol" != 'file' ]]; then
+    printf -v "$1" '%s' "$2"
+  elif [[ "$_gnp_protocol" == 'file' ]]; then
+    printf -v "$1" 'file://%s' "$(cygpath -m "${2#file://}")"
+  else
+    printf -v "$1" '%s' "$(cygpath -m "$2")"
+  fi
+}

libexec/get.d/file

@@ -206,10 +206,8 @@ _@go.get_file() {
     if [[ "${url:0:1}" != '/' ]]; then
       url="${PWD}/${url}"
     fi
-    if [[ "$url" =~ ^/[^/]+ && -d "$BASH_REMATCH/Windows" ]]; then
-      url="${BASH_REMATCH}:/${url#$BASH_REMATCH/}"
-    fi
-    url="file://${url}"
+    . "$_GO_USE_MODULES" 'portability'
+    @go.native_file_path_or_url 'url' "file://${url}"
   fi
   _@go.get_file_impl "$download_dir" "$filename" "$url"
 }

tests/portability/native-file-path-or-url.bats

@@ -0,0 +1,32 @@
+#! /usr/bin/env bats
+
+load ../environment
+load "$_GO_CORE_DIR/lib/portability"
+
+@test "$SUITE: return unaltered path if _GO_PLATFORM_ID isn't msys-git" {
+  local result
+  _GO_PLATFORM_ID='foobar' @go.native_file_path_or_url 'result' '/foo/bar'
+  assert_equal '/foo/bar' "$result"
+}
+
+@test "$SUITE: return unaltered path if protocol isn't file://" {
+  local result
+  _GO_PLATFORM_ID='msys-git' \
+    @go.native_file_path_or_url 'result' 'https://mike-bland.com/'
+  assert_equal 'https://mike-bland.com/' "$result"
+}
+
+@test "$SUITE: return updated file system path" {
+  skip_if_system_missing 'cygpath'
+  local result
+  _GO_PLATFORM_ID='msys-git' @go.native_file_path_or_url 'result' '/foo/bar'
+  assert_equal "$(cygpath -m '/foo/bar')" "$result"
+}
+
+@test "$SUITE: return updated file:// URL" {
+  skip_if_system_missing 'cygpath'
+  local result
+  _GO_PLATFORM_ID='msys-git' \
+    @go.native_file_path_or_url 'result' 'file:///foo/bar'
+  assert_equal "file://$(cygpath -m '/foo/bar')" "$result"
+}

tests/template.bats

@@ -1,6 +1,7 @@
 #! /usr/bin/env bats
 
 load environment
+load "$_GO_CORE_DIR/lib/portability"
 
 # By default, the test will try to clone its own repo to avoid flakiness due to
 # an external dependency. However, doing so causes a failure on Travis, since it
@@ -42,9 +43,8 @@ CLONE_DIR=
 setup() {
   test_filter
   export GO_SCRIPT_BASH_{VERSION,REPO_URL,DOWNLOAD_URL}
-  NATIVE_LOCAL_URL="$(git_for_windows_native_path "$LOCAL_DOWNLOAD_URL")"
-  CLONE_DIR="$(git_for_windows_native_path "$TEST_GO_SCRIPTS_DIR")"
-  CLONE_DIR+='/go-script-bash'
+  @go.native_file_path_or_url 'NATIVE_LOCAL_URL' "$LOCAL_DOWNLOAD_URL"
+  @go.native_file_path_or_url 'CLONE_DIR' "$TEST_GO_SCRIPTS_DIR/go-script-bash"
   EXPECTED_URL="$FULL_DOWNLOAD_URL"
 
   if [[ -z "$TEST_USE_REAL_URL" ]]; then
@@ -75,31 +75,6 @@ assert_go_core_unpacked() {
   restore_bats_shell_options "$result"
 }
 
-# Converts a Unix path or 'file://' URL to a Git for Windows native path.
-#
-# This is useful when passing file paths or URLs to native programs on Git for
-# Windows, or validating the output of such programs, to ensure portability.
-# The resulting path will contain forward slashes.
-#
-# Prints both converted and unconverted paths and URLs to standard output.
-#
-# Arguments:
-#   path:  Path or 'file://' URL to convert
-git_for_windows_native_path() {
-  local path="$1"
-  local protocol="${path%%://*}"
-
-  if [[ ! "$(git --version)" =~ windows ]] ||
-    [[ "$protocol" != "$path" && "$protocol" != 'file' ]]; then
-    printf '%s' "$path"
-  elif [[ "$protocol" == 'file' ]]; then
-    printf 'file://'
-    cygpath -m "${path#file://}"
-  else
-    cygpath -m "$path"
-  fi
-}
-
 # This mimics the tarball provided by GitHub.
 #
 # This could probably become a general-purpose utility one day.